[craigawoodman]

Given I now have the car back in my hot hands (and have taken it from one side of Australia to the other - on the back of a trailer), it is time for an update.



As those of you who have seen my other posts, I have gone down the path of forced induction. Given that the car is mostly used on the track, I was looking for more horsepower. Flash did not have any more kits in the pipeline, so given my timeframes (car was to be ready for the first round of competition in January 2011), I ordered the 928 Motorsports kit.



I ordered the kit in December 2010 with a delivery date of very early in January 2011. The kit did not make it, being shipped on the 25th of January 2011. I will cut to the chase, the car was at the mechanic's on the 10th of January (I was also having the engine rebuilt) and I picked it up (almost complete) on the 19th April 2011. The installation is not yet complete due to several issues which I will discuss below.



There are numerous issues that I have had with this kit. I am not sure if some of these are due to the engine being brand new (higher compression), but the majority are due to the kit's design. I went into the process with my eyes open, but even so, I did not expect the amount of grief I have had to work through.



When I looked at the dyno graphs on the 928 Motorsport's website, the power drop off over 5,500rpm was a concern. I was not sure if this was due to exhaust backpressure, belt slip, injector fuel delivery, etc. To make sure that we did not grenade a brand new engine, we always intended to run an aftermarket ECU to ensure that the car was custom tuned.



Issues found;



1. Driving the supercharger of the back of the belt does not work - the belt slips from idle and the knurling on the pulley creates severe wear. Solution - machined the supercharger pulley to accept a double ribbed belt (i.e. ribs on both sides of the belt). The kit comes with a 6-vee belt, but currently running a 5-vee belt. Will have to do some more work as pr below on pulley sizes, etc and get a 6-rib belt.

2. Injectors lean out at high rpm - at high rpm and WOT - the injectors are at 100% of capacity. The supplied 45lb injectors were replaced with 60lb injectors (note that the rising rate fuel regulator was also removed and the fuel delivery controlled by the ECU through pulse duration only).

3. Radiator and A/C condensor had to be dropped around 20mm to fit.

4. Supplied fan with kit does not work. Re-installed original twin fans.



By using an aftermarket ECU, there is no need to run the MAF sensor. This has been removed.



We have a custom made intercooler mounted in the front of the engine bay.



Here is what the kit should look like according to the 928 Motorsports Website (not sure if I am allowed to post this - but it is an image taken from their website);

Here is what our installation looks like (this is prior to the bonnet/hood being re-installed);

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[banditsc]

Sorry you had to re-engineer their kit, but the end result looks really clean.

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[craigawoodman]

After dyno'ing the car to tune it, the engine advance has to be knocked back at high rpm to prevent pre-ignition (this is running 98 RON unleaded - which I think is slightly lower than your 93 in the USA).



So we will have to install the thicker head gasket (the standard thickness wide fire head gasket was used in the re-build), to de-compress the engine slightly. This will also most likely allow slightly more boost to be run. To do this a replacement blow-off valve is required, plus a replacement crank pulley to speed up the belt (this will also require some review of belt length and suitability, etc).



End result is exactly what the 928 Motorsport website claims for the kit (it should as it is limited by the relief/blow off valve). However, this should be much more reliable.



First graph is power (rw) and torque. Second graph is power (rw) and boost. Not that boost drops off over 6,000rpm. There is more boost there if the engine will not pre-detonate.



I have added some photo's of the car with the bonnet/hood attached (I will start a new thread for ideas on how to make the bonnet look better while forcing air through the intercooler).



There is still work to be done;



1. Car could not be driven (bonnet was last item back prior to my departure) - so the car struggles to idle when hot - this should be a 30minute fix by the tuner).

2. Ducting required under the intercooler to direct air away from intake and towards back of car

3. A/C is leaking at firewall

4. Review hard cut for tune (while tracking the car at Bathurst - the hard cut appears to be around 6,700rpm).

5. Review options to decompress head and to make more boost. Mechanics believes that if you can run a bit more boost and advance the engine, there is around another 80 to 100hp available.



Impressions; It just goes harder. The flat torque curve does not give a peaky level of performance. It is easy to drive on the track, but I am getting used to the additional speed, so I need to revisit braking markers, etc. Running at around 9/10th's I managed to knock around 4 seconds off my lap time from last year (this was conservatively braking). Mark Croudace managed to almost match my lap time in a N/A 968 - but I am not sure how hairy his lap was (he was carry much more corner speed than I was willing to) - it was easy to crank out a 2:44 with the supercharger.



Problems - the cost of doing this right. There is the cost of the kit (of which almost all of it was thrown away - we used the head unit and the mounting brackets - that is about it), the cost of the replacement ECU and custom tune, RSBarn hi-flow exhaust (the car now has a menacing growl about it and even my wife said it was too tame standard), custom intercooler, even more replacement injectors, etc. The pistons and head were ceramic coated and the car ran cooler than when it was N/A.



So there is still more work to be done, but it is a good start. I would not under-estimate how much work you will need to put in to make this kit work properly and reliably. Based on what we have seen with this build, I would not recommend running the standard kit by itself - it needs a lot of additional work to be reliable.

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[craigawoodman]

Bandit,



You caught me in mid-post. I did not have a chance to drive it prior to putting it on the trailer (the battery was also flat) and taking it to Bathurst (google the Mount Panorama race track). I got to Bathurst late afternoon on the Thursday and took the car off the trailer to try and get it scruitineered (only to be told to come back in the morning), so I put it back on the trailer and took the car to the motel we were all staying at. I got up very early on Friday (our group were the first for drivers briefing and on-track) to take it for a quick spin. It had two new Dunlop Dizerra's on the passenger side front and rear (drivers side in USA) and it was cold and wet and dark.



As I got out of town I opened the throttle in third and it lit up the rear tyres in the wet. This was interesting.



Over the course of the weekend, I gradually got used to the car. As you can see from the dyno graphs, it has a very flat torque curve, so it is easy to drive - it just seems to rev quicker. Going up Mountain straight last year I would hold fourth gear up to the braking mark - this year, if I did not change up prior to cresting the intermediate hill, I would hit the hard limiter very quickly, so I was carrying a gear higher. Same down Conrod straight, last year, I would get into 5th gear and hold this flat through the kink. This year, I was changing up into 6th prior to cresting the hill and backing off for the kink. So is it quicker - definately. Do you feel as though you have something unwieldly under you - not at all, it is linear and progressive - not like a turbo at all.



As per the post, I will have lots of more work to do yet. Hopefully once we de-compress the motor, we can run some more advance and boost and see what it can deliver then.

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[banditsc]

In the end it sounds and looks like you will have a nicely tuned car. It's just to bad you had to go thru all that. I guess it's really tailored to what you wanted now though..

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[craigawoodman]

Bandit,



It is only half finished. Knowing that it's ignition is retarded and that it could make another 60 to 100hp will be an incentive to get it finished. THere are still some changes that need to happen (like the idler/direction change pulley that is currently counter-levered) to improve the design.



The next couuple of months will most likely be taken up house hunting prior to my family moving over in July. So it depends on how much to get the work done and how busy I will be. Having to go through finding a new mechanic, etc will also be a pain.



I should note, that it only spun the wheels in third when it was wet and it had a new tyre on the rear. In the dry, there is no problems with traction, but on a wet day - throttle control will be an essential.



It is getting there. I think it also needs some form of heat shield between the intake filter and intercooler to prevent it drawing hot air into the intake. So, some fine tuning is still required.

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[flash]

i agree that it sucks that you had to go through this, though i have to give you credit for your tenacity - i would have given up a long time ago and returned the kit - good on ya



two things i see that are not optimal:



1. the intercooler location while in a very effective location for cool air intake, adds a lot of underhood pressure that may cost you speed due to the increased lift



2. unless you have added some sort of divider to separate it from the intercooler, and a deflector to direct the air to the air cleaner, the location means that it is taking in hot air - this immediately increases the intake temps and makes the resultant post intercooler temp higher than it needs to be



did you ever test intake temps without the intercooler? have you checked to see what the intake temp pre and post charge is? i would not be surprised if they were all similar



but again, a great effort, and despite the cost and hassle, obviously you are getting closer to what you wanted, which is the ultimate goal

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[craigawoodman]

Flash,



I agree on both counts. It was suggested that we run the bonnet slightly raised at the rear to allow air to escape - but that was a little too Japanese for me. The whole bonnet/air to the intercooler needs a lot more thought. Given the timeframes, they modified my existing bonnet rather than the spare that I bought for the purpose. So I have another bonnet that I can play with. I was thinking that the scoop would be more central and provide air to both the intake and intercooler, with some trailing vents like a 917 on the upper edges.



Not sure if this is going to be easier to do to a fibreglass bonnet or a metal one, we will have to see.



As per previous posts, it needs both a deflector under the intercooler to direct air away cleanly from the bottom of it and also between the intake and intercooler itself to prevent heated air being drawn into the engine.



The whole car has only been running for two weeks, so there is a lot of water to go under the bridge yet.



Also, the re-circulate function of the relief valve does not work as there is no piping on the intake into the supercharger to plumb it to - it vents straight to atmosphere.

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[jfrahm]

Cool. You should not need to capture the air from your recirculation valve if you are running a standalone with a MAP sensor. The ECU does not know or care about the air you are dumping.



I got a 6 rib belt working by putting another idler bracketed off one of the alternator cradle mounting bolts and looping a longer Volvo 6-rib double sided belt over it. Works good but I do not have the correct size supercharger drive pulley for it. I tried it with a smaller pulley and that was fun until I hit 4.5psi at 4K RPM and it slipped. This was with a modified alternator pulley that is far from ideal for driving the blower.



I have a 2.25" drive pulley on the lathe right now, which developed a bad speed control pot and sidelined me last weekend. When I get better at cutting pulleys I intend to find an optimal size and shape to get good drive. I might use a boost limiter. I am not particularly interested in the max boost at 6500RPM but I am amused by the thumping great heaps of power in the midrange I have been getting.



No boost control comes with the kit, boost is only limited by the ability to spin the blower. The recirculation valve is designed to bypass air when the engine is drawing a vacuum against the back of the throttle plate and the supercharger is delivering way more air than the motor can manage.



It's interesting that you got the stock fans to fit. I have not had a problem with the single fan but the stockers appear to be much better. I might have to see if I can use them when I transplant the SC system to a nicer car.



-Joel.

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[craigawoodman]

Joel,



If there is no boost cotrol or relief, why doesn't the boost keep climbing with engine rpm? At around 6,000rpm, it starts to drop off, when it should be climbing with engine rpm.



I am talking to Raptor about pulley sizes and will eventually get a custom made crank pulley (larger diameter) made to speed up the supercharger and hopefully get up to around 8lbs of boost once the engine is de-compressed.



What boost levels are you running?

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[Cloud9...68]

Craig,



I'm very sorry to hear about all your troubles with the install, but at the same time, it occurs to me that by the time you're done, you and the mechanic(s) you're working with will probably have a great design worked out for a 968 supercharger for track applications, especially if you are able to coax 8 lbs boost out of it. Any thoughts about sharing what you've learned, possibly in the form of a recommended set of parts that others could assemble, along with a set of instructions? Just a thought...

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[tamathumper]

Any thoughts about sharing what you've learned, possibly in the form of a recommended set of parts that others could assemble, along with a set of instructions?

Yeah, you could call it a *kit*! Oh, wait...

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[tim944s]

Thanks for the write up concerning the re-engineering. This was exactly my hestitation before handing over my hard earned money for ANY kit. I wonder if you will be crucified for 'Copying' someone else's kit because you have essentially kept only 15% of the original? In any case, I feel better now that I have been able to enjoy my car without any problems. I do feel for those that have been spending more time in the garage working on solutions for this kit instead of enjoying the open road. As such, I have been following the ongoing development on the 928 Motorsport kit on multiple forums and it never ceases to amaze me how many are hanging in there. I have yet to see or hear of a satisfied customer, and the closest I know of a street application is Joel's test mule. How can a developer instill any confidence in any buyers when there is so much of a mess out there of a so called bolt on kit? I do realize many have taken it on themselves to modify the kit for racing applications but it seems sad really that the average Joe is throwing hard earned money out the window for something that does perform as advertised. That is, of course, anyone is actually buying it for a street application. I hear the usual banter, "Oh yeah, once I have my money saved up I will be buying one too!"



I apologize to those who may have bought the 928 Motorsport kit. My intent isn't to slang any of you personally or for buying this kit. If it had not been for Flash, I too may have found myself in this boat as I was seriously considering it. In the end, I am glad I waited as I have not been very impressed with the product that 928 Motorsports has offered.



Having followed this whole affair for quite some time, it amazes me at the supporters for the 928 Motorsports kit. I have had quite the exchange with the misinformed....



The following is from another site, which shall remain unamed, but re-enforces why I don't frequent there....







Hi there



Having followed the development of Carl's supercharger kit from the beginning, I am interested on some personal insight from you.



I am not sure I understand your statement



"regardless of whether or not you have some pretty photos of someone's supercharger, (as the laws of physics surely do permit it), that's not the point... READ the thread. don't come here and spam about some defunct equipment that's: out of production"



More specifically, can you give me some details on some 'other' kits and comment on the advantages and disadvantages compared to Carl's kit? I have been interested in modifying my car and I am always open to XXXXXXXX members commentary. You seem to be a very knowledgable individual when it comes to the various systems on the market.



Thanks for your time. I look forward to hearing from you.



Tim







well, one of the most difficult parts to source is the correct transmission for going to 300 + horsepower...



porsche sold the last transmission with the 180 mph 6th gears a couple of years ago....



today was a very good day for me because i saved about 2,000 dollars on the critical parts necessary for building the equivalent of the "968 Turbo S" box.







that being said, Carl's kit will make about 360 flywheel horsepower using a 2.75" exhaust with a resonator and turbo or maximum flow muffler.





there is only 1 other supercharger kit worth mentioning. they may have stole the idea from Carl (this is the contention of some of the guys) and built a very nice intercooled supercharger that costs about 2 grand more than Carl's kit. it arguably makes more power. i tend to believe that. their add is lowballing the 100 hp figure. with my exhaust, their system would likely make 120 hp over the 255 hp that my n/a system makes running the straight pipes.





http://www.speedforceracing.com/index.php?productID=736









rs barn also was selling a kit that was a complete rip-off of Carl's design.





i doubt many systems have sold from either of the three vendors.





i respect Carl's work the most and would buy his system if it were me putting down the $$$$$.







I had looked at the SFR system many years ago and was holding out until I knew more or had more than one option, as the SFR kit was very expensive. This is not a decision to take lightly.



Can you elaborate a little on the RS Barn kit. You had stated that it is a complete rip off of Carl's system. What specifically did they steal or rip off? Is RS Barn facing any litigation concerning their blatant copying of Carl's forced induction system? Your personal experience with RS Barn would be appreciated as I would surely like to highly informed as to who I could potentialy be dealing with if I am looking for parts for my beloved 968.



As I am trying to an unbiased consumer, your experience with Carl would be welcomed. I assume you are very familiar with his work due to your respect from him. May I ask what line of product you have purchased from him? I may be interested in also purchasing some items from his inventory.



Once again, thank you for taking the time to answer my questions. Your feedback is appreciated. I look forward to hearing from such a well informed XXXXXXX member.



Tim







the guys who really have the inside track on how the counterfeit was done are the new jersey 968 guys......



steve, damian, raj, fox and the guy with the mint green car and a few of the other guys.....



they have better details about that and are the ones to talk to.



they all harbor extreme dislike of rs barn even though the shop is in pennsylvania.







WOW. Sounds complicated.



So going back, your experience with Carl and his products?



Tim





he races 928s. including a race in colorado you may have heard about. sells the best brake package that money can buy, a surgically enhanced 928 gts kit... sells superchargers, and other accessories. well liked in the 928 community.



helped me sort out my brakes and decide on what equ to run.. we've talked on the phone only a few times about a thing or two but it's always an education.





Oh I see. So you haven't actually used any of his products? I would think though that a shop like RS Barn would have some intimate knowledge concering the 968, no? They work and produce parts specifically for the 968. I have talked to Pete and Max and they seem very knowledgable. It is unfortunate you are receiving your information second hand. I cannot seem to find any info on the XX forum that says they should be a questionable shop, no?



Having looked at both kits offered by Carl and RS Barn I am unsure as to where specifically the two kits are the same other than the fact they are forced induction. Can you point out as to what components or is it the actual design that has been copied? Am I missing something here.



Wow. You are sure quick on the responses. Thanks.



Tim







The responses seems to stop after this......?

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[tim944s]

Oh sorry..one last thing. Craig...nice car!

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[craigawoodman]

I will try to respond to the questions posted since my last update. In terms of what was supplied with the kit and what was retained or removed;



- Raptor supercharger (retained - but discharge rotated approximately 180 degrees to allow intercooler to be added)

- Mounting brackets (retained, but idler pulley arrangement will have to be re-designed, may eventually re-design the entire mounting arrangement).

- Rising rate fuel regulator (removed)

- Upgraded 45lb fuel injectors (removed - had to install 60lb units - see below)

- Supercharger drive belt and pulley (drive belt removed for double sided belt and pulley machined to suit - see below)

- Radiator fan (removed - original fans re-installed - see below)

- Piping (removed to allow use of intercooler)

- Relief valve (retained - see further modifications)

- Intake air filter and piping (removed)



Modifications made to kit for this installation;



- Use of dual sided drive belt. This was due to the original design using a single sided belt and driving the supercharger off the "back" of the belt. The belt slipped from idle and the knurling on the supercharger drive pulley to increase friction caused wear which was obvious even after only idling the car. Drive pulley supplied with the kit was machiined to allow the use of a dual sided multi-groove belt.

- Use of an intercooler. It was stated that an intercooler is not necessary for the boost that this kit produces. I think that there are two issues here, 98RON premium unleaded in Australia is somewhere roughly halfway between 91 and 93 unleaded in the USA. THe engine was also fully rebuilt prior to the install, so is making full compression. As such the engine suffers from pre-ignition at high RPM and had to have the ignition retarded to prevent this. The use of an intercooler will hopefully also reduce this tendancy through cooling the air delivered to the engine.

- Replacement ECU. An Autronic prgrammable ECU was installed (I have also purchased a Civenco ECU - but no-one over here could program it and I ran out of time). The kit from 928 Motorsports does not provide a replacement chip or any upgrade to the engine programming for the addition of the supercharger. As per above, using the replacement ECU showed that the supplied 45lb injectors were at 100% duty and struggling at wide open throttle and high rpm, along with the pre-ignition and knock without retarding the ignition at higher boost and rpm's.

- Larger injectors - as per issue above, the supplied upgraded 45lb injectors were maxed out at high engine rpm and boost. This may also be due to the installation of an RSBarn high flow exhaust and the air demand/throughput from the engine. Flash has seen a similar issue with the use of the RSBarn headers and exhaust (air flow is so high that the fuel demand is huge).

- Changed intake arrangement - by going to an aftermarket ECU, there is no need to run the factory MAF unit. This means that the plumbing of the intake is now simply an intake pod filter directly into the supercharger air side. This also removes the issue of having to modify the MAF to "straighten" the air as per the kit's instructions.

- Radiators and air conditioning condensor had to be lowered by around 20mm to clear the supercharger head unit.

- The supplied single radiator cooling fan did not work when dyno'ing the car, so the original OEM dual fans were re-installed.



Work also done at installation to car;



- Full engine rebuild, replacement of cams (worn sprocket teeth), ceramic coating of combustion chamber and pistons to reduce heat load on engine.

- Installation of RSBarn hi-flow exhaust and cat.

- Upgraded suspension hardware (racer's edge)



Work still to be done to finish the job;



1. Decompress the engine to allow more boost to be run and more ignition advance (Install thicker widefire head gasket). Mechanic believes that there is somewhere between 60 to 100hp still to be made with more boost and more advance on the engine.

2. Machine replacement pulley for crank to speed up belt and ensure supercharger runs optimally. Raptor unit has a 3:1 step up internal gear ratio and can run at a max speed of 46,000rpm. I need to know the diameter of the standard crank pulley so I can work with Raptor to get a custom crank pulley (and other pulley's for alternator, etc) machined. This may also require a replacement dual sided belt - there is a belt available which is 50mm longer than the belt originally supplied in the kit (the belt I am currently using is 25mm shorter than the original belt). Let me know if anyone wants the Gates part numbers.

3. Finish ECU tune of car. As car did not have a bonnet (hood) as it was being modified, the car could not be road tested after inital dyno mapping. Engine struggles to idle when hot (could also be an issue with the single mass flywheel - possibly).

4. Add a shroud under the intercooler to duct air away and inprove flow

5. Add a shroud between intercooler and intake to prevent hot air being injested into engine.

Possibly vent the bonnet at the rear to draw additional air out of the bonnet to improve air flow and reduce lift.

6. Review options for bonnet for air intake and intercooler (asthetics as I am not completely happy with current set-up).

7. To run more boost, review the blow off valve/recirculating valve arrangement (as per boost curve from dyno - boost drops off after 6,000rpm - this could be belt slip, but it should keep climbing with engine rpm unless it is being relieved.

8. Possibly review the use of an accusump to ensure oil levels into engine (crankcase windage tray was installed when rebuilding the engine).

9. Review oil vapour collection as this is now not connected back into the intake.

10, Review radiator fan logic within ECU programming as fans are either on or off (both at same time). Engine runs much cooler as these now kick in at 90 degrees C at full fan speed.

11. Possbly install a boost gauge so it is obvious when the car is making boost and how much. I could not drive the car prior to taking it to a track day and found that the engine very quickly runs into the hard cutout in fourth when I crested a hill and had a slight downhill assist. This was disconcerting as it was a new engine and I was not used to how it performed and what it was programmed to do - we simply ran out of time and rushed everything at the end.

12. Review engine hard cutout limit - currently set at 6,700rpm.



What I would do differently next time.



1. When rebuilding the engine, consider knife edging the crank and using either forged or titanium rods to reduce rotating mass. This would increase horsepower and engine responsiveness and also life. I have the upgraded rods, so I thought about this but discounted it given how much I was spending already. In hind sight, I should have gone the whole hog. Not sure what this would do the the requirement for the balance shafts.

2. Decompress the engine by using the thicker head gasket.

3. Buy the kit and do a lot of homework prior to starting the job (everyone else can learn from my mistakes - so this is partly done).

4. Allow more time. This took over three months to do. Some of it was learning how to modify the kit and wait for parts to arrive (custom intercooler, replacement belts airfreighted from the USA, etc).



In the end, the installation (I cannot call it a kit) works well. It does not feel peaky and drives just like a 968, but with more grunt. In this respect, it does not feel that impressive, until you realise that you are carrying a gear higher almost everywhere on a track. It is dissapointing that I will not have an opportunity to drive the modified car on the tracks in QLD to see how much time it has removed from my lap times - so I have no real benchmark now.



So the process is far from finished. It is just now actually drivable.

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[craigawoodman]

Tim,



Specifically to respond to your questions.



I went down the 928 Motorsports kit for two reasons only. One, I had to keep the A/C - it is too bloody hot over here to not have it (so that removed the Speedforce racing and Ninemeister kits). Two, Flash had sold out of his kit and at that stage was not doing the second run. I have actually purchased one of Flash's kits as part of the second run (and believe me, if I could have got one in January - I would have probably pulled the pin and stopped working with the 928 Motorsports kit). Flash has been sympathetic and listened to me rant when I was pissed off at the world and the kit in general and he tried to help out and source a kit from the initial batch that had not been installed.



Given that the car is mostly used for track days, something more suited to that application was also more of a priority and I thought that there could be more upside with the 928 kit - but this would be at a cost (how much I did not know at the time).



I went into the process highly skeptical about the kit itself. For this reason, I was always going to run an aftermaket ECU and wanted to intercool the set-up (once again due to our ambients over here). I was also very nervous about supercharging the car as it had traditionally run very hot (I was running two oil coolers, radiator ducting, etc when N/A and still getting a hot engine). I was also nervous about the dyno figures as the engine power should not fall off like it does above 5,500rpm on the 928 Website graphs. I could not believe honestly that the standard 968 ECU and chip could cope and was programmed to cope with a supercharger. Yes the MAF should measure the air flow, but it has to be out it's normal parameters and be in wide open throttle most of the time?



I was hoping for more power than the standard 928 motorsports kit, but I now know why this cannot be achieved safely until modifications are done. So more work to get it right.



Honestly, if you were to look at this kit, I would only buy the mounting hardware and pulley arrangements, the supercharger and leave everything else on the shelf. THe supercharger is made in Australia and retails for $2,200 as a complete unit, so somewhere around $2,750 to $3,000 for this and put the remaining $2,000 towards the repalcement ECU, pulley machining, tune, etc. THe kit cost me $5,000, the ECU, additional injectors and custome tune and wiring install cost another $4,800, intercooler $700 plus the piping and labour to drop the radiators, etc. There was a lot of re-work (take stuff in and out to get it to fit, so the costs were higher for the labout component).



So Flash's kit is a relative bargain at $5,000 and it mounts up and works from day one. No grief, no stress, no re-engineering required.



As I have a second supercharger kit that is more suited for a road car coming , there is a manual black converible for sale - I just need to convince my wife that I should have it. Unfortunately I bought her an Audi A5 convertible, so having a second cab in the house is going to be a hard sell.



I also want to make a tarmac rally car at some stage, but this will initially be N/A and possibly then move to a 968 Turbo RS replica in the future. I also probably need to win Lotto to fund all of this and the house to put all the toys in.



So in summary, would I recommend the 928 Motorsports kit as it stands. Absolutely not - there is too much work to get it to be a proper installation that works. But if you want to have a kit for motorsport, I think it will work with some more fettling and produce around the 260kW/350hp at the rear wheels - which was where I was aiming to end up. This would be around 410hp at the crank, which would be comparable to the Ninemeister kit in full trim. That should enable me to annoy GT3 drivers greatly. But if you factor in the cost of the engine rebuild and the supercharger kit, ECU, etc - for roughly the same price, I could have had a Powerhaus 968 Turbo engine - not sure which is the better option.



Might need some even bigger brakes and testicles to go with the power upgrade.

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[Cloud9...68]

Craig,



Thanks for the very detailed post. It's amazing what you've had to go through, and how much progress you've made in only three months. Hopefully in the end you'll have a world class, track-applicable system, and with the A/C intact to boot. This really makes me respect all the more the effort Flash had to put in to come up with a kit that simply works out of the box, and continues to work flawlessly after nearly 100K cumulative miles on the units on peoples' cars. Oh, wait, he all he did was rip off 928 Motorsports' design. How could I forget.... Uneblievable.



I'll be interested to see how you ultimately deal with the fuel enrichment requirements with your high flow exhaust. Are you worried about engine longevity given the high fuel demands under certain conditions, particularly before the engine is warmed up? I realize it's primarily a track car, but still, I'm sure you're not too keen on the idea of needing to rebuild the engine any more frequently than you have to.



As far as reducing the rotating mass, I was advised by very knowledgeable people that knife-edging the cranks on these engines is in general a bad idea. Simply put, the large inline four is so inherently unbalanced that you need some mass in the crank to keep these forces in check. I weighed mine, and it's 59 lb (28.8 kg)! Flash had a very informative post in which he stated that lightening the crank is theoretically possible, but it is a very complicated undertaking, because you have to consider the interplay of the harmonics of all of the rotating components (pistons, rods, flywheel, clutch, pulley, balance shafts, etc.), and basically re-engineer everything. Not for the faint of heart. I decided to keep my crank at the stock weight, but went with light weight Wossner pistons, and lighter (but stronger) than stock forged Pauter rods. I'm also having the crank cross-drilled to improve oil flow. This is exactly what RS Barn did with the crank on their 300+ HP NA motor, so I feel pretty good about the approach.



One other thing you might want to consider, if you haven't already, is a larger oil cooler. Lindsey Racing sells a unit that has 3X the capacity of the stock cooler, which I'm also going to buy. Between that, the slightly increased side clearance between the edges of the rod big ends and the edges of the crank journals with the Pauter rods, and the cross-drilled crank, I'm hoping to significantly improve the longevity of my engine through improved oiling. And I'm definitely getting the 3-piece cross-member, to improve access to the bottom end of the engine in the future.



Best of luck with all the work you still have to do to get the supercharger working to you satisfaction.



Edit: Your latest post hit before I finished mine, and I see you're running two oil coolers, so ignore the comment about the oversized cooler.

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[craigawoodman]

i had to add this photo. The car has done 5,000km on the back of the trailer from Brisbane, Qeensland to Perth, Western Australia. Photo was taken in the middle of nowhere at the South Australia/Western Australia boarder (look up goole maps for Eucla Western Australia).



Tow car and trailer did 5,500km from Gladstone to Perth. Left Bathurst on Sunday at 11:00am and arrived in Peth 11:30am Tuesday for roughly

4,000km in two days.

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[jfrahm]

[quote name='craigawoodman' timestamp='1303857271' post='109090']

Joel,



If there is no boost cotrol or relief, why doesn't the boost keep climbing with engine rpm? At around 6,000rpm, it starts to drop off, when it should be climbing with engine rpm.



I am talking to Raptor about pulley sizes and will eventually get a custom made crank pulley (larger diameter) made to speed up the supercharger and hopefully get up to around 8lbs of boost once the engine is de-compressed.



What boost levels are you running?

[/quote]



You have to remember that boost is a measurement of the amount of air your engine is *not* flowing. It is the difference between the amount of air the supercharger has provided and the amount of air the engine can process.



Also, the supercharger as an air pump does not operate in a linear fashion. If you look at a compressor map you see that there is a complex relationship between RPM, pressure ratio, and flow. The higher the pressure on the outlet side, the harder it is for the supercharger to move more air to the outlet. Also the higher rpms can affect the ability for the supercharger to grab more air.



Then there is slip in the drive system. It's a reality in any belt drive system and naturally as the force required to move something goes up, and the RPM goes up, the belt's progression across the face of the pulley goes up. Just like tires wear out faster at 100mph than 50mph despite no obvious wheelspin.



So boost is not likely to be linear wrt RPM over a large range.



Now, if you are actually seeing the boost flatten or drop at high RPM your belt is slipping a lot. I have seen this with the too-small pulleys I have been messing with. Boost shooting up and then leveling off or dropping. In this case the belt drive is working OK delivering (I'm making up numbers) 10 or 15 HP to the blower at 4 or 5k rpm, but when asked to deliver more HP at higher RPM it loses traction.



I was seeing 6psi floating up to touch 7psi at shifts with the stock stage 2 kit. With my double sided drive I have not yet run it with a viable real-world pulley. My goal is 6-ish psi again but with a more comfortable belt tension. More would be interesting and I could see trying to get 8psi but my early experiments do not suggest this is possible.



I think the crank pulley on the 968 is just too small to make much more boost. Carl's larger crank pulley should sort this out. The 928 guys get enough supercharger drive with 70-100mm pulleys to make over 500hp so it's clear it can be done.



I'd hoped the 52mm pulley I tested would hold, that would have been pretty awesome. This was a converted alternator pulley and not a good design for supercharger drive but my impression was that I could not improve it enough to grip over maybe 5 or 5.5 psi. What I saw was 1 psi at 2500rpm and 4.5 at 4K, and 4.5 was about all I got as the belt started to slip. I did get the idea from this run that I might like a system designed to deliver this midrange boost and then use a boost limiting valve to cap it off at 5psi, thus limiting the HP needed to drive the blower. The car would not be as impressive on the dyno (I don't care) but it sure is fun to drive with that much midrange power.



Also I think the double sided belt increases the effective diameter of the crank so a 58mm pulley for the smooth side application might deliver less boost than a 58mm pulley driven by the thicker double sided belt. This means I might see the boost I want with a larger pulley than I expect.



Cheers,

-Joel.

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[flash]

very early on in the process, i tried to buy just the head unit and the brackets, as i did not want any of the rest of the kit - i felt that the rest was ill-conceived, carl was not interested in doing any further work, and i wanted better



he said no way, and you had to buy the whole kit or nothing



then i made a deal to buy just the head units, but i found that the air cooled design was going to ultimately be a problem, and went with the rotrex (which i had been looking at for this car since the chip shootout test over 6 years ago) forcing an entirely new design



i wonder who the poor schmuck is that is listening to those who would grossly misinform the masses? i also wonder when somebody is going to set them straight?



i am still interested to see intake temps though - i'd also like to see how the unit is doing on heat - the efficiency goes down as the heat goes up, and with it being air cooled, i tend to think this may be the issue up top

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