[craigawoodman]

All,



A plea for help to the collective supercharging wisdom within the forum. I have again tried to battle on with the 928Motorsports kit, fitting the new mounting bracket (more wrap) and using a 6 rib belt, but I am still getting belt slip (I have the larger crank pulley installed as well). I get to 3.5psi on the dyno and then slip until no boost at 6,500rpm.



What I am chasing is what boost levels are people getting using a 6-rib double sided belt. 3.5psi just seems stupid prior to slip.



What size drive pulley are you using, what belt tension (and how measured) and what boost/hp levels have you achieved?



I am the point where the next investment will be $1.00 worth of petrol and some matches. Masochism has nothing on this.



Flash - still got any un-modified head untold and mounting available?



Thanks.

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[Dubai944]

Craig,



Were you getting more boost before you changed the belt and pulley setup?



What diameter supercharger pulley are you using at the moment? I use a 3 inch on my supercharger and it's 8 rib. Each head unit will be different as to what size pulleys it can turn, depending on the drive ratio. On the pro charger slip became chronic with a 6 rib belts as soon as I tried pulleys smaller than 2.5 inches.



Have you checked it is not something other than belt slip? Faulty blow off valve or leak in a manifold hose or similar?



I use a proper belt tension gauge (same as below) and correct tension range is 120 pound for a new belt down to 80 pounds for a used belt.

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[craigawoodman]

Dubai,



I was getting exactly the same boost prior to fitting the larger crank pulley. Not sure what the SC pulley is, but it is likely to be around 2.5" (there has been a collection of them). I have fitted the new mounting bracket that increases wrap and the guys doing the dynoing have pulled apart the intake and measured pressure drop and made sure it is buttoned up right.



There is a new blow off valve as the old one had burst - so if anything I might have been getting more but going to atmosphere.



Where did you get the belt tension gauge?



Thanks,



Craig

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[vliegwielolaf1234]

I have been following your SC install , and i think i would call it a day and install one off flash his kit's instead (if still availble .



Not much joy this way having a sc on there only doing so so .



I think it is way better to go from a good function kit .



Thanks for trying , because reading about is made my choice a lot easier , and got a working kit instead .

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[flash]

i am currently running over 7lbs with no slip whatsoever.



yes, i have a few kits for unmodified heads. i split the kits up into subassemblies so people could choose their poison.



you know how to contact me.

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[Dubai944]

Craig,



Would love to see some pictures of your belt setup. I would try some belt grip spray and see what difference that makes. It isn't a good permanent solution but it will validate your assumption about belt slip if that's the primary cause. If it's slipping badly you should see a bit of boost increase with a good dose of belt grip spray. And do the belt up tight.



Is your new crank pulley and charger pulley hard anodised? Plain aluminium pulleys polish up quickly and don't grip well. If you have a spare pulley for the charger, another test to see if it's just mechanical belt slip is to cut straight grooves across the pulley which hugely increases the pulleys grip on the belt. I did this on some of my early pulleys and was able to see up to 2psi more. It will also chew the belt up eventually, so not a long term solution but again it will give you an idea if the standard pulley slip is the problem. I raced for a while with cross cut pulleys before I went to a better 8 rib belt solution.



Flex might be another problem, check and see if the head unit is moving off plane under load.



In the end, pulleys which are too small just don't work well. I decided 3 inch pulleys on the head unit were as small as I wanted to go, but you have to have a correspondingly bigger crank pulley to make it work.



What do 928 motorsport say? Reading the long development thread on the 'other' forum it seems he has developed a stage 2 setup and claims to be getting good results. Are you using his bigger crank pulley? It's only an inch bigger, which is still not enough to allow you to use really decent size charger pulleys. Seems like it is just a bad basic belt arrangement on that kit. Don't give up though, at the end of the day if the head unit is sound getting it to spin properly is just solving basic mechanical drive issues.



I got my tensioner sent to me from someone in the US. i see them for sale on various online stores. Even Amazon sells them: http://www.amazon.com/OTC-6673-Universal...B000I198J0



Steve

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[94SilverCab]

Craig,



I admire your fortitude...a litre of petrol and a match looks like a very sound investment (please post pics).



Jay

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[Cloud9...68]

[quote name='craigawoodman' timestamp='1358927358' post='137836']

am the point where the next investment will be $1.00 worth of petrol and some matches. Masochism has nothing on this.

[/quote]

Craig,



If you've been following my no-start thread, I'm at no where near the level of frustration you must have reached through your incredible ordeal, but still, I can understand the sentiment... Best of luck.

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[jfrahm]

Before I got the Phaeton belt I was hitting a 5psi wall with other belt configurations. Mainly I had been using an extra idler that added wrap around the crank pulley and also used up enough belt so I could use a Corvette or Volvo double sided belt. I thought I was still getting belt slip. I could move the 5 psi limit up and down by changing pulleys With the Phaeton V6 belt cut down to 6 ribs I was still seeing the 5 psi max. Come to find I had lost the boost/vac signal to my re circulation valve. Stupid. It was teed of something that blew off a connection to the evap system or something. Ah well. I refitted the vacuum system and can now get 7 psi with a 50mm blower pulley and tons of good midrange. My goal, if I can be bothered, is to limit max boost because honestly I like the car the same with anywhere from 3-7 psi at the top of the rev range and the midrange grunt is what I am after. With the current arrangement I get 5psi at 5000 RPM. Stock crank pulley and currently no extra wrap idler.



The pet store has some good vacuum/pressure tubing and fittings for fish tanks. Petsmart here in the States has nice silicone tubing, little manifolds and whatnot.



-Joel.

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[KRAG50]

As long as we're talking Boost, who has a source for a boost guage that has a max reading of 10 lbs, 15 lbs tops? all I can find are the ones that go to 30 lbs and I don't think the resolution is great for a 5 lbs system.

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[craigawoodman]

Dubai,



The pulley on the SC is plain Aluminium, no cross cuts. Do you have a website for anodized pulleys or know of a vendor over here that can do this.



I am running effectively the latest 928 Motorsports set-up. Bigger crank pulley, new mounting bracket and a Corvette double sided 6 rib belt (was running a Phaeton belt with a rib cut off previously).



Advice from vendor is to tighten the belt. My mechanic over here has previously over tightened the belt on another install and bent the top idler pulley as it is cantilevered.



We will tighten up the belt to buggery today and see if it makes any difference.



Missed my plane home last night due to a connection so doing this by remote control today and it is my wife's birthday. So I will have to first climb out from under the pile of poo I land in when I get home.

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[craigawoodman]

Sorry, other option I am seriously looking at us removing the intercooler if I cannot get to around 10psi and then there is the option of putting the head back to standard compression.



I have a D1 kit that I bought as an insurance policy after initial frustrations, but it is in storage, and there is a manual cab over here that is for sale (the owner is a member of the forum) that I need to convince my wife I can seriously look at (bit hard after buying her a new Harley Sportster Anniversary and a new Fat Boy Low Anniversary for me - the toy cupboard is getting seriously full).



Hence the desire for an I modified D1 kit where I will at least get 7psi. If nothing else, I serve as a community service to others of what not to do.



(Flash - I will email when I get home - new counter post HD crash, so not sure all of the contact details were recovered).

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[Dubai944]

Craig, lots of places do hard anodising and it's not very expensive. I last had 4 pulleys done at A Grade anodising at Ormeau for $100, and that was only because $100 is their minimum charge. If you can't find a local anodiser you could courier them to A Grade.



If you do get to 10psi, you will still want the intercooler. Which intercoler are you using? The stock 951 intercooler I use shows a pressure drop of several psi (I get 12 to 13 psi pre intercooler and 10 in the manifold) but it does drop the temperature effectively (up to 90 degrees C temp drop at high rpm from my logging).



Changing your compression ratio might make it work better with low boost, but it doesn't really solve the problem. If the head unit has the capacity to flow enough air, you have to get it to spin properly.



Pity you are not still on the East coast. I would be happy to give you some help.



Steve

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[craigawoodman]

Dubai,



I may be heading back to QLD hopefully soon.



They have tensioned the buggery out of the belt and managed to get 6psi after the intercooler. The intercooler is a custom PWR unit.

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[Dubai944]

Well, not so bad then. Hope it tunes up ok.

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[flash]

given that most intercoolers drop 2psi, that means 8psi boost. that's just over the tipping point of needing an intercooler. at just a touch over 7lbs i am just under that boost level, and am fine without one. intake temps peak at 160F on a hot day. no problem. i wouldn't want to sustain that temp, though i think it would be ok, but i don't track the car, so it won't be an issue. were i to track it, i'd be shooting for 10lbs which means i'd probably have to run one size smaller pulley to overspin the unit and make up the lost boost from the then added intercooler, and then retune, yada yada. i could probably hit about 375hp though without much effort (i'm already up over 350).



as a reference, on an S2, that boost should give you almost 350hp peak.

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