Stan.Shaw@Excell.Net

I didn't look at that thread, but one of Gary's desire is to keep the CIS. I think that is a key limiting factor based on my limited research.

hacker-pschorr

That is a good point to remember. I posted that link more as a reference for the 16V guys.

mark kibort

If you really think about it. we are not talking big hp/liter here
So, if we can get 293rwhp out of a 2 valve 5 liter, and Ljettronic!, and a stock S4 with 5 liter and 4 valves/cylinder makes what, 305rwhp with the same mods, i dont think its out of the question given that the euro throttle body and S4 TB are near the same size, the valves are near as large and the euro cams are actually more agressive. So, sure you wont have that 3400rpm torque hump, but hp should be right up there with the 4 valve engines up to a point.
mk

GaryJ

Thanks guys very interesting input.

OK here is the next logical question. If it looks like it could make sense to put the stroker in but the CIS is my limiting factor, what do I need to do to go to an EFI system. I like the simplicity of the CIS and feel pretty confident I am not going to get stuck at the top of a mountain some where with it but maybe I am just being a little paranoid toward the EFI systems. I see too many guys at track days with their laptops plugged in (not 928’s) trying to tweak everything and 50% of them never finish the track day.

Also I am still trying to gather information about the CIS upgrades that 928 Motorsports has, they are supposed to increase flow by 30%. I do have a message into Carl.

I have owned my car for a long time and have a great history with it so I am trying to maximize the performance of this particular car.

Again your thoughts are most welcome.

Gary

hacker-pschorr

CIS is a great system - when it works. Problem is parts are getting hard to find & very expensive. This is why I'm dropping CIS on my track car for EFI (not sure what system yet). As soon as someone puts together a base system for 928's (early or late) it will benefit everyone (assuming they share / sell the info).
I'm not sure what plans Louie has on sharing his system - that is one possibility. I know 2V4V has some experience running MegaSquirt on a 928. I have an e-mail into him to research that option for my car.

I'm in the same boat as you. I want EFI on my 79 - but I do not want to dive in head first with the setup either. It's worth every penny if I can buy a working base setup, go from there. I may end up going with Autronic for the simplicity of it.

BC

You need to spend money early on in EFI to make it stable. Dyno tuning is important. Usuing good sensors. 90% of the issues are wiring ones.

GaryJ

Thanks Hacker,

Let me know what EFI you end up going with. I guess my decision is going to be to take the project as far as the CIS will go or as far as the heads will take me, of course dollars being the ultimate judge.

Gary

GaryJ

Hi Brendan,

That is my belief that it is a bit tricky to set up at first. Again making me want to stay with the simpler CIS system. I will be interested what 928 Motorsports CIS upgrades offer.

Thanks,

Gary

GaryJ

Hi Guys:

I talked to Carl at 928 Motorsports and it seems that he has the goods to make the CIS work up to and beyond 500HP.

I had a good talk with Carl and he made a pretty convincing argument to build the engine with my original 79 crank in the new 5L block and to supercharge instead of put in the stroker crank. Since now the CIS could keep up and the forced air would help with any flow limitations of the heads. I know Carl is a big advocate of supercharging so now I ask the question of you guys does this approach seem to make more sense?

Thanks,

Gary

Stan.Shaw@Excell.Net

What I do, is add up everything I will need with either option, then review what I would expect to end up with and confirm my expectations are valid.

I don't like to be on the "bleeding edge", although many love to be there and without them there wouldn't be any new developments.

So for me, since strokers in 928s have been proven more often on the road course in racing, it was a clear choice.

GaryJ

Hi Stan:

I take it you are voting for the stroker. I clicked on your car link and it looks like your have a regular 5L EuroS motor. Have you since added a stroker crank to that motor or are you suggesting that the stroker would be a more stable option in your opinion.

I am like you and not really one to be on the bleeding edge, I was actually surprised I haven’t heard from anyone that has put a stroker crank in a 16V motor. It does make me wonder if there is a major pitfall I am not seeing.

Thanks for your thoughts.

Gary

Stan.Shaw@Excell.Net

Hi Gary,

You can't really consider my direction, as our purposes are not the same.

My race car is currently without ANY motor....

I decided not to stroke a 16v motor, as by the time I was done, I would have so much into it, and still not have the same hp as a 32v motor. This is based on the many that have gone before me in building road racing 928s.

You need to focus on your intended purpose and find others who have done what you want before you.

I am definitely not the most knowledgeable on all of this...

GaryJ

Stan:

Thanks again for your thoughts. It is looking to me that the major extent of the development on the 16V 928 is a 5L EuroS Hybrid or to supercharge the 4.5L stock 79 engine, they both seem to end up with about the same performance. I thought there would be more but it looks like after that people switch over to the 32V models. I am sort of stuck in that my particular car is special to me and I want to maximize its performance but I definitely want to keep a drivable car. This is in no way a purpose built race car it will see some track time but mostly be just my fun car for mountain running and Sunday cruising.

I was hoping to get something in the mid 400 HP range at the crank, upper 300’s at the wheels. Maybe I am just a little too optimistic.

Thanks again.

Gary

Jim bailey - 928 International

OK lets talk some numbers... Devek stroker 6 liter S-4 very old numbers showed 318 hp 384 ft lbs torque (stock was said to be 266hp 282 ft lbs) The great leverage effect of a 95.25 mm stroke made a big increase in torque 36 % BUT ONLY 19 % more horsepower. The rest of the intake cams exhaust systems would NOT support much more horsepower higher RPM . Then a 6.5 liter S-4 with head work ,high flow exhaust in 1998 made 407 hp 460 ft lbs torque. Note that still was a high torque relatively low horsepower engine. And in spite of the theoretical ability of the 2 vale head to match a 4 valve configuration The very best that a custom ported head with bigger 944 valves did with Euro intakes (thousands of dollars of head work) race cams race headers exhaust was about 425 hp on a 5 liter at 7,500 rpm or so. In the words of the engine builder "the two valve is a street head". What I think you would end up with stroking a Euro hybrid would be much torque but an engine which would peak at about 5,000 rpm and the horsepower which would not be that high would be declining. Build what we know works and enjoy the approx 300 RWHP for a long time.

bcdavis

Carl has already built a couple really beefy 2v engines, with CIS, and supercharging, and runs his car on the track all the time. So if anyone can help you keep your 2V CIS car in the game, at a high horsepower level, Carl's the guy to help you... Sure, there are other options, but they are going to be DIY setups, and trial by fire. With Carl, at least he has already been there, and done that, with a high-horsepower CIS car, and sells all the parts. Supercharger kits, oil control kits, CIS mods, etc... Any stuff he develops to make his CIS car work better, could be used on your car as well.