[Rob in Oz]

I suppose many of you have digested your 968 Owner's Manual and paused at the Full-power Curves page (115 in my manual). I just wonder how Porsche, with all their engineering expertise and attention to detail, were happy with those torque and power curves. I gather they're a result of the VarioCam operation and maximise torque at 4200, but hey, would you walk away from a result like that these days. I'd be interested to see comparable curves (for N/A) cars from RS Barn, Promax etc - have they done better with "modern" technology, or does the VarioCam make it just too hard?



Rob

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[ds968]

I'd actually be more interested to see the power curves graphs from other ( N/A ) sports cars / GT manufacturers of the same 92-95 era and look at what they were able to achieve as compared to our cars . Who knows, maybe if we leave the 911 and the supercars ( Ferrari , Lamborghini, etc ) out of that picture, maybe the 968s power curve is better than most other N/A " sports cars " of its era ..??

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[Ryan]

At the time they were getting about 80 hp per liter of displacement and that was pretty darn good for a n/a car.



Now Ferrari gets like 120 per liter for their n/a engine which is amazing.

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[Darryl]

I tend to agree with Dan and think that a fair comparison would be with other similar class from the same era. That, and give the fact that it has always been rumored that Porsche has had to "dumb down" certain cars so they didn't outperform the 911 flagship product.



- Darryl

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[flash]

well..............



like with many things, there is a little bit of truth on all sides. porsche did choose not to let the 968 outperform the 911. that one is a no brainer. they do the same thing today with the cayman. it would be very easy to add another 50hp to the cayman, but then they would never sell another base model 911. that will never happen.



as for technology and getting more out of the 968, to date nobody has really messed with the technology aspect of the engine. they have tried things in combustion chamber shape, compression, cam design, etc, but not the technology. as far as i know, anybody who has at all messed with that, other than some minor tuning, has merely disabled it and gone for the more primitive methods.



a new control system, a more refined variocam, and a new injector system design could probably reap another 30hp. but, would it be worth it? we can already add a bit over 20hp with some simple stuff. would the extra 10, which would then preclude modifications, be worth the cost?



porsche did the best they could do with the budget available. you have to remember that they needed to build something that fit their credo regarding longevity. as long as the company has been around, they have felt that the engines need to last, with little service, relative to other performance cars. they chose the tortoise over the hare philosophy.



the 968 did very well in its day, both on paper, and on the road. we tend not to think so much of it today, because outputs have gotten so much higher. back then though, even the V8s of the day were only putting out a marginal increase over what we had. even the standard vette only made 300hp.

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[MB968]

Here's what Mazda was able to do with 2.5 litres. The KLDE is the derated US version at 164 hp, and the KLZE is the Japanese version of the same engine at 200 hp (dfferent cams, larger flow heads and 10:1 compression vs the KLDE's 9.2:1). The Mazda has a 3 way variable resonance induction system (two sets of butterfly valves in the intake to change runner length at three points in the rpm range that you see on the torque curve).



So, if you factor in the extra 20% larger engine of the 968, the 240 hp is comparable in terms of HP/liter. Although with a 11:1 compression ratio, variable valve timing (which the Mazda doesn't have), and the 60-2 tooth wheel giving them control every 6 degrees of crank rotation (the Mazda is only every 60 degrees), I’d have expected a little stronger output from the Porsche.



   

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[Cloud9...68]

As Flash says, there are a lot of factors to consider, but to me, the key is the specific output. Yes, many modern engines put out more power than the 968, but they tend to be significantly larger displacement as well. For a 3.0 liter inline four to put out 236 hp using early '90s technology, with the reliability and longevity considertaions Flash mentions, isn't too bad, imho. Especially when the simple air box mod and a decent chip can get you up to the 250 hp range (assuming a fresh engine), which puts its specific output about on par with a new 370Z.

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[Rob in Oz]

Perhaps I wasn't clear in my initial post - I wasn't referring to the specific outputs, which are commendable, but to the odd shape of the power and torque curves due to the influence of the VarioCam. What I was looking for was some power and torque curves from aftermarket chips and how they dealt with the effects of the VarioCam. Sorry for the confusion.



Rob

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[MB968]

Rob, I'd like to see that too. Since my system is stock, I'd like to know what a chip and some better flow would do for our engine. Seems like there should be some untapped potential left to collect. But, I've yet to see dyno charts to point the way.

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[flash]

there are plenty of charts out there for the chips. you just have to look. we definitely do NOT want to get into yet another chip discussion.

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[MB968]

Don't know about Rob, but I wasn't looking for a chip discussion, just some dyno charts, before and after for various modded 968s. The dyno plots for the stock KLs I posted above were done my Michael Fortier. Over time, Michael, and several of us posted dyno runs on the KL engines with various mods. Changes ran the gamit from mild (<200 hp at the wheels) to wild (over 450 whp, or crazy (over 650 whp). It was nice to get a feel for what was achievable with various changes and amount of time/effort and $'s spent. Nice to know whether you were building a modded DD, a dependable DD/weekend racer like I was, or a stock class racer, or a heavily modded one.



I know there have been a reasonable number of 968s used as DD/weekend racers or class racers. I for one would like to see some dyno runs with listed mods to know what it takes and what one gets.

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[flash]

no worries - it's a touchy spot that goes back 9 years to the chip shootout test i did, and wrote an article about.



i think you may be overestimating the number of pioneers modding this engine. it's not like the japanese stuff. there just aren't enough of them around, and porsche owners tend not to modify things as much anyway. most of the people doing such work on these have been lax in doing step by step testing, and did not generally use real controls in their testing. it's really expensive to do it right, and the difference is often so small that it does not justify the expense. i've personally spent over $50k testing and developing things, and not all of them worked. that doesn't translate well for most people. the market just isn't there to justify developing much of anything.



as an example, there are about a half dozen different chips, 2 cold air intakes, 2 headers, and 4 cat-backs. that's about it.



there also are not huge gains to be had by the bolt on normally aspirated stuff. the variance from like item to like item isn't much, and the net gains are modest. the difference between one set of bolt-ons and the next is perhaps 6 or 7 hp. it you want to spend a ton of money, you can get 300hp normally aspirated, but you give up driving it on the street, and your car will be down for months while the engine is being built.



as for charts, the amount of variables can easily skew the results. for that reason alone charts frequently just aren't worth the paper they are printed on. it makes me nuts when people focus on charts. this is a pet peeve of mine. too many people hang their decisions on a dyno chart, but have no clue how to read them, or what things could have affected the results. the chart in your post above is a perfect example. for starters, they ran that in 3rd gear, and most places run it in 4th. that affects the drivetrain loss. the chart does not say if it is at the flywheel, hub, or wheel. it does not specify camber angle, tire pressure, tire size, wheel weight, or strap tension. all of those affect the results. it doesn't mention any atmospheric conditions either. still, some idiot might look at a chart like that and say "hey, i can spend x dollars and get y horsepower"



that being said, the charts for anything available for the 968 are here. do some searching and you'll find them. i've posted quite a few myself. however, there is little point in redundantly re-posting the same charts. it's not likely that such a thing would be productive, and it could certainly be misleading. there is already enough abbreviated information out there now. we want things to be complete and with context. we also want the consequences of any mod to be carefully considered. i'm afraid that a simple string of charts might lead somebody to an ill-considered decision, due entirely to them not doing their due diligence and research first, because they grabbed a snippet of information and ran with it.

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[MB968]

Sounds like it is a touchy subject.



The KL unlike other Jap. engines has little aftermarket, just like the 968. Only a couple CAIs, a couple of header brands, etc. etc. That is why I and others made our own SC or turbo setups. There are none commercially available.



The KL is similar to the 968 in that it was finely tuned from the factory, with little gains from aftermarket add ons.



I didn't post the large amount of data that support the chart that I posted. It would take pages. In the KL world we completely appreciated the need to appropriately use dyno runs. They are not absolute indicators. But, properly used they can be quite useful.



I'm not overestimating the number. I'd venture to say that there aren't as many KL's being full raced as there are 968s. It's never been more than a handfull.



And, I suppose I just didn't search as much as I should. But, I don't recall seeing dyno runs from any of the engines that are doing wheel to wheel racing, either in a stock class, or modified. If you say they are there, I'll look harder.

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[flash]

that's exactly what got me into developing stuff. there just wasn't much of anything out there, and what was out there wasn't up to my standards.



dyno runs are only applicable if you do them on the same day on the same car. it is easy on a car of this power to see a 10hp difference from variables, and when you are talking about a max of 25hp gain from all components combined, that's just too huge to be useful. dynos are great tuning tools, but worthless for comparison of products.



as for dyno charts of cars being raced, they would all have to be under the maximum numbers, so they would all look about the same. also, most modifications are not allowed. so, a comparison of charts of bolt on stuff would be fruitless, and any comparison charts of one-off setups is obviously useless.



everybody doing anything forced induction has charts out there, and they are easy to find. i think i'm the only one doing any extensive testing though.



by the way, what the heck is a KL? (killer lincoln?)

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[MB968]

See, I told you it wasn't very common. The KLDE, and its jap and euro version the KLZE were the designations for the 2.5l V-6 that Mazda made from 1993 to about 1999. It was used in the Mazda MX6, the Mazda 626, the Euno 800 (or something like that) and the GT version of the Ford Probe. I think the KL block was also used for some of the other Mazda V-6s in the same era. Was a sweet engine with forged crank & rods, piston oil squirters, stainless valves, etc, with a redline of 7500. Liked to rev, and great torque as low as 1000 rpm, so very drivable.

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[flash]

there used to be a bunch of stuff out there for the probe. they had a whole series racing those cars back in the 90s. it was pretty popular. i knew a few guys running them.

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[MB968]

It was a lot less common than you might have thought, but compared to the 968 we did have the benifit of numbers. Fortunately we had a lot of members on the forum, probably over 10,000 worldwide back in the late 90s. We had a special Forum for Bulk Buys that would be organized by an individual. Without it, we wouldn't have had much aftermarket support. This allowed us as a group to approach big firms and with a pre-paid large enough order, to get them to make a unit for our cars. But, in spite of the large number of members we often struggled to get enough committments for a minimum order. When we went after Quaife, we were only able to get about 12 committments. Fortunatley quaife was willing to take our order for such a small quantity. That was how most of the performance parts got made, but the numbers were small. In some cases, like quaife, they continued to sell the units on special order. But, others like the 17.5mm rear sway bar, which was made by one of the major suppliers, only a single run of a few dozen were ever made.

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[flash]

10000 members? wow - we barely had that many cars made worldwide. i remember a bit about the probe, and there was quite a bit of suspension stuff, as well as some bolt on goodies for the engine. i never really got my head around the car, but i know that ford motorsport put quite a bit of effort into prepping that car. i used to see it at sears doing pretty well almost every weekend. i never saw a 968 on the track at all.

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[Grandpa#3]

I don't want to step on any sore toes and know nothing about an article by Flash on Chips. What would be the best chip today for our engine? I can tear an engine apart, inspect, repair and put it back together properly. Chips are a completely foreign body for me and must plead complete ignorance on the subject. Any words of wisdom on the chip subject will be much appreciated.



Cheers,

Larry

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[flash]

it really depends on what you want - do some reading in the "Chips and Salsa" area



http://www.968forums.com/forum/81-chips-...-no-salsa/

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