wjk_glynn

When PowerHaus built Dan de Gruchy's 3.0L turbocharged 968, they used Bosch 52# injectors.

With 91-octane and 1.0-bar of boost, it made 338 bhp and 322 lb-ft at the rear-wheels on a Dynojet 248C. With 100-octane and 1.3-bar, it made 400 bhp and 377 lb-ft at the rear-wheels. Those numbers are according to PowerHaus, not independantly tested.

Karl.

Porschefile

I'm sure Wayne's comment was due to the fact that the stock 37# (~370cc) injectors do not physically flow enough volume to support 400+whp. It's just pretty much physically impossible. Maybe with a rising rate FPR and some other little tricks you might be able to get close, but that's one incredibly wrong way to go about modifying a higher hp car. 52# (~540cc) injectors are more than sufficient for the 338whp of that other car you mentioned. Generally, on most 4 cylinders, ~55# injectors should be good for as much as ~350-400whp and much above that then you'd want to go with ~75# or larger. As always, there are plenty of exceptions.

jgporsche

Powerhaus seems to tune via fuel pressure. Every time DFastest951 talks about what he can accomplish, he bases things on what he was told about fuel pressure and boost pressure. IIRC, he uses 48# or 52# injectors on his 480whp car.

Andial951

ohhhh.....So you wrote for Excellence? Very cool.

Was there ever any articles on the ANDIAL built 951s? I have a copy of an article but Im pretty sure it wasnt from Excellence.

wjk_glynn

If I remember to do so, I'll re-read the article tonight and make sure I didn't mis-quote the "stock injector" part.

Karl.

wjk_glynn

Just a few, and you'd be amazed at the amount of effort it takes.



This is the only one I ever found and it didn't go into a lot detail:

"Building a 944 Turbo To Challenge The V-8s" by Robert Bruce Duncan - #26, April 1991, page 73
Duncan provides an overview of the first 944 Turbo fitted with Andial's 2.8L stroker kit. The car also had some Turbo Cup suspension components fitted to improve handling. While there is some detail on the parts fitted, there are some glaring deficiencies – e.g. there are no power or torque ratings mentioned.

Karl.

SoloRacer

One thing to consider is that there is often misinformation in magazine articles. I was told by Jon w/Milledge that was the case with the article on my 968 Turbo. I'm not sure what parts of the story are inaccurate though as he didn't expand on that. It could be the builder's way of keeping things secret. I agree with the stock injector not flowing enough just based on what I have seen on other cars (RX7's). Obviously the efficiencies are different for rotaries vs. pistons and rotaries typically take much larger injectors but the principals are the same.

Andial951

Hey I found something in your link on your second post. Its the 9th article down.

The Link

EDIT: Hmmmm....well it seems the article is really about the racecar that happens to have an ANDIAL 2.8L kit in it.

George D

Graham's 2.8 used the stock injectors. I live in Tucson, and visited PowerHaus on many occasions. The 2.8 cars that PowerHaus built in the mid to late 80's used the stock injectors. They just ran the fuel pressure up and let them run at MAX duty cycle. Kinda scary now that we have in car A/F meters. I wonder what the ratio's were on those cars. The dyno's that I did back then with my car only recorded RWH.

I remember driving with the PowerHaus guys and when we heard detonation, we would just add octane booster. I'm amazed that my car only blew head gaskets.

George

wjk_glynn

Doh... I'd forgotten about that other article -- thanks for catching that.

So to summarize, there were 2x articles on cars that had Andial 2.8L strokers in Excellence as follows:

Street car: "Building a 944 Turbo To Challenge The V-8s" by Robert Bruce Duncan - #26, April 1991, page 73
Duncan provides an overview of the first 944 Turbo fitted with Andial's 2.8L stroker kit. The car also had some Turbo Cup suspension components fitted to improve handling. While there is some detail on the parts fitted, there are some glaring deficiencies – e.g. there are no power or torque ratings mentioned

Race car: "A 944 Vision Becomes Reality" by P. Giesold Stout - #67, February 1997, page 73
Pete Stout provides a detailed description of Lee Brown's 944 Turbo racecar. Built by Vision Motorsports for POC competition, it features numerous modifications – from an Andial 2.8L stroker kit to AIR bodywork. A picture of that car cab be found here: http://www.americaninternationalraci...ry/944wb12.jpg

Karl.

951and944S

Interesting flashback......

TS

billindenver

Not sure that I would agree that the stock injectors are far to small. I pulled 335 at the rear wheels on 16psi on stock fuel injectors and high fuel pressure. I then turned it up to 22psi and ran/raced it that way for 4 years and very near 80k miles. No ill effects. I never did re-dyno it though...just never got around to it. I've since bumped up to 55#, but the stock fuel injectors never left me lean according to my A/F guage..and at 180k miles with less than 5% leakdown...I doubt the best salesman could convince me I was running lean.

Just another data point to consider, your mileage may vary but don't always believe the nay sayers who proclaim gloom and doom..having never tried it or known anyone who has. One supposed expert can say something on the internet and next thing you know there is a large following swearing his theory is gospel. I'm not referring to anyone in particular, just saying you can't believe everything you read. The stock injectors, with higher fuel pressure will certainly flow 400hp. Is it a great idea? Well, that like beauty is in the eye of the beholder...but my car did it for a very long time and never left me hanging..or wanting for more.

Bill

wjk_glynn

I didn't make a mistake -- the article did say it was with stock injectors. Now the article did not comment on the gas octane, but if the 415-rwhp pull was made with 1.3-bar, I'd guess it was with 100+ octane.

I should also add that they were already in the process of installing larger aftermarket injectors (they didn't specify the brand/model) and were aiming for 440-rwhp. Stout's test driver was with the the larger injectors installed.



Those are interesting comments. In the Excellence article, Stout said:

"Gillies uses his car as an everyday driver. He has racked up more than 60,000 miles on this highly modified engine in only two years, proving that modified, turbocharged cars can have good reliability and longevity... He spends a fair bit of time running PCA, POC, and NASA events, and his 944 Turbo has yet to let him down at track events."

Karl.

944CS

remember that 944's use batch fire and not sequential

Porschefile

That's hardly the "proper" way to go about doing it IMO. It sounds like you got away with it just fine, but that's running the injectors on the ragged edge and it wouldn't take much to have a failure. Bosch/Siemens injectors (I thought the stock ones are Bosch?) tend to be more resistant to higher pressures and running above 80% duty cycle for extended lengths of time, though that's still taking a big risk. Injectors are cheap and engine rebuilds aren't. It's fairly common knowledge that running over 80% duty cycle for extended periods of time can lead to failure (sticking wide open among other things) of a large majority of injectors. I'm not being a naysayer with unsubstantiated claims. The stock injectors are 37# which is about ~370cc give or take a few. On plenty of other non-944 cars I've personally seen that ~300whp is the realistic max if you want to keep things safe and leave yourself a bit of room for error. Above 300whp roughly ~45#+ (~470cc) injectors are a good idea. Then it only goes up from there. Injectors are anywhere from ~$250-450 depending on the brand, so I can't really understand why someone would risk blowing the motor to save a couple hundred bucks. Do it right the first time and it will never be a potential issue. In the early days of chip tuning with our cars, there might have been issues with drivability, idle etc when tuning with larger injectors. However, as far as our aftermarket has progressed, that's no longer really a problem.