Shane

Major Kudos John!

Tony

good stuff!
When i get home ill try and cut and paste/combine your chart ontop of the other ones ive made with the SC cars(Voretch..Whipple) and the DEVEK stroker. The chart may get a bit busier but its kinda cool to look at them all on the same scale.

Now..
Sure would be fun to "cut and paste" your application onto an s4!
If i recall the one picture i saw of your exhaust manifold its acutally very crued looking (no offense)..crued, meaning simple in design. All exhaust ports on one bank exit to a single plenum..then the Turbo is bolted below it. Very cylindrical in appearance.

What is the difference between an '81 and '87+ exhaust manifold? I think its one more stud..or one less...cant recall? I dont think it would be an engineering feat to duplicate a manifold for an S4 and plum it all to the intake in similar fashion. Leave all the electronics stock.

On paper it sure would seem like a simple bolt up. The 81's have no more room than the later cars under the hood.

With such great results, im left to wonder why Marc T or others havent pursued this more? Marc?
Im hoping Tom Cloutier gets a set of turbo headers made for his S4. We've seen the S4s run in the teens boost wise...would be awesome to see the teens via a twin turbos!

Jim Nowak

John,

225's? Are you kidding? Do you have a death wish? No wonder your Gtech times were slow. Get some new rims and tires so you can use all that power. What is that saying......"power is nothing without control."

Tim Murphy

Hey John, congrats on some great numbers! (and a belated happy b-day too).

I’m glad to see that you got things sorted out enough to bring the car to the dyno, the results are very interesting. I really like the representation of the 8psi vs the 12psi and how they lay right on top on each other until the wastegate comes in. It would be interesting to lay the curves over the centrifugal and twin screw dyno charts running at the same boost levels. Not necessarily to compare the HP numbers but to compare the slope of the curves. If you have the file from the dyno shop I’m sure someone here would be able to do an actual comparison within the Dynojet software vs trying to interpolate the numbers by resizing a document (no offense Tony). Doing a rough calculation based on the charts you are making about 13 rwhp per pound of boost. It looks like the turbos are running a little out of steam towards the end of the run by the way the power and torque falls off and I think if you could turn it up to about 16psi it would give you power increase all the way to redline. (What is redline on the 2 valve cars?) I can’t remember what you have all done to the internals of your engine so I can’t tell you whether I could condone that or not but I would think 400rwhp is a possible figure based on the slope of the curves. My biggest concern would be, of course, having enough fuel throughout the rpm range. How was the air/fuel ratio? I know you said it was a little fat to start but how did it finish up? Anyway, I have to run for now, packing to go on vacation. Anyone in Orlando the next 2 weeks?

Tony

No offense at all Tim, that was all i had to work with


Orlando huh....The Human Trap that the mouse built!

John.

The AFR was somewhere just shy of 12:1 at the upper end. I remember seeing 11.8 or something. Getting the fuel just right takes a lot of time with my setup.....sometimes I wish I did have a simple rising rate regulator but to do that on L-jet and get the fuel to feed a lot of power with stock injectors would be tough. I run 914 1.7 liter units.....they are pumping at just shy of 50 psig static on the rail.....on boost the rail pressure is about 60 psig and it is about 37 at idle under high vacuum....all in all it is a WIRED SYSTEM, but works well. The only next logical step would be to go with a stand alone fuel and ignition system like the DTA or other....prices on those units are coming down and it is what I would do if I would build a car from scratch.....for example you could map an ignition curve to retard at the peak torque point where the threat of detonation is highest....there is just so much that can be done with a programmable system. I think how crazy it is, me running L-Jet and a distributor with modified "pressure retard", but the car runs like a scalded dog so who am I to gripe about that? Sometimes simple is good.

Tim, if you decide to build that centrifugally blown L-jet car I would highly recommend this MAF conversion.....I think you would be very surprised at what you can do with it. You could even use the same MAF I am using from Pro-M. I'm 100% sure the MAF, calibrator, injectors and adjustable regulator could support 8 lbs no issue whatsoever, maybe even 10-11 lbs.....then you can re-tune the entire fuel curve. You would just have to buy the parts from Pro-M and Split Second, all the R&D is basically done.

I am done tinkering for quite some time. Tim, while you pack for Florida, I pack for Hawaii and my Honeymoon...I have to be careful not to talk too much about the car right now....wedding is in exactly one week....let's just say in one week I will be, umm....busy.

I do think a better set of cams would do the car some good....the stock power curve also falls off after about 5300 RPM, so I think a different cam grind could help with the top end power....any suggestions....I'm sure Marc Thomas has something out there that could work. Now why the heck didn't I stroke this thing....I am trying to remember? Oh well, as the saying goes, hindsight is always 20/20! It is nice to have just 4.5 liters anyway. I feel like the black sheep of the 928 community.

Anyway, sorry for poking so much fun at Lag, but I just could not resist...regardless I know he has a tough skin for sure! Lag are you reading this?

I would love to have an S4 to toy with....I don't know how much wider the heads actually are, but I am sure some turbos could be fitted to the car.....a real trick setup would be mount them under the fenders and bring a wicked heat wrapped header out through the inner fenders and then build like a heat shielded turbo box up under there.....there would then be lots of room to route the charge pipes back to the front. Two massive intercoolers mounted under the front of each fender, then discharge and combine into one massive throttle body pipe feeding an intake manifold....or maybe two manifolds...custom made of course. My first step would be to pull it and do the same drill I have done to my bottom end....Nikasil the block and put a forged piston in it....probably 8.5 or 9:1 compression. Probably go with a very high flowing Garrett or maybe KKK for the Porsche authenticity? I am sure that is very possible, but it would be mad coin to put such a car together....probably like $10,000 for all of that I would guess. I have it all down in my head, anybody have a doner car. Bet I would get into "significant other" trouble for attempting a stunt like that!

Strangely enough, my IHIs are not all that efficient by today's standards, but they get the job done nonetheless. I have loved driving the car this weekend, but MAN does it like to drink gasoline. Oh well, it is now below freezing here so I should just put it away for the winter and focus on my new marriage! She rented me a 355 for a day in Hawaii, now that should be fun, but there are funner things for the honeymoon than a 355! I don't know if my Audi has a dead battery now or not I have been driving this Bastardized creation all weekend!

Fastest928

John,
You are letting "them" off way too easy

You did it right....forged components, moderate boost, and made great numbers with very old technology turbos...

No math buchery here...just some real good work!

Well done!

Marc
DEVEK

BTW - I sold off my twin turbo project..turbos went to Tom C, heads off to a "SC" project, crank out east, etc. Cause I realized.... what was I going to do with 1000 bhp TT 928 except look at the dyno chart and brag..

I would rather be driving...

Tony

Heck...
Id run it on the Dyno, get the 1000+hp...
brag til i was blue in the face...
call HOT ROD mags....PANO..Excellence...
put a little red boost **** on the dash that can only used in conjunction with a special key. A key that someone else would keep in there possesion.
They would evaluate my state of mind and sanity before giving me the key and allowing me to drive it on the street..

"de boost" and "boost" at will...and drive it!

Lagavulin

Firstly, congratulations on dyno-ing your car..

…now there’s no more speculating for anyone, which admittedly, does take some of the fun out of it. But you know, that’s what the SAE charts are for, to remove any doubt, and to keep everyone in check, myself included.

Congratulations on your numbers! Besides the actual numbers themselves, they say that you did a good job reassembling and tuning the engine. The tuning will never stop as I’m sure you already know, but to me, that’s part of the fun of owning a fast car.


Observations…

According to the numbers, your car put out exactly what is to be expected from an NA 220 crank hp engine.

Spreadsheet Calcs, 220 crank hp, 85% IC efficiency, 75% turbo thermal efficiency:

08psi = 305.69 rwhp
12psi = 361.33 rwhp

Your numbers also indicate that the log-style exhaust manifolds did not impede horsepower production as I had speculated, which tells me that the stock exhaust manifolds are indeed as bad as several threads on this board make them out to be.

There is some speculation that you may need more cam. But if it's the shape of the power curve that's in question, it *may* be indicative of the turbos running out of breath (..as Tim has already suggested), or, is merely a function of how the wastegate operates; I have no experience with either, and am only speculating.

So if new cams are installed, NA power will increase, as well as hp under boost. However, the overall shape of the power curve will remain the same as the turbos *may* be the hardware shaping the curve. Even if this were the case, it can be viewed as a positive thing as we all have different views on what kind of power curve is most advantageous, depending upon how one drives the car.

Again, congrats on your nice numbers.



And finally, your ranting…

Oh well.

Fastest928

Most 4.5L engine that I have dyno'd made no more than 200 rwhp, most only make about 180-190 rwhp, some even less. But the average is only 180 - 190 rwhp at rated compression.

John, just about doubled the output of a stock engine at 11-12 psi (that is what is written on the dyno sheet for psi range).

Yeehah!!

Marc
DEVEK

Fastest928

Most 4.5L engine that I have dyno'd made no more than 200 rwhp, most only make about 180-190 rwhp, some even less. But the average is only 180 - 190 rwhp at rated compression.

John, just about doubled the output of a stock engine at 11-12 psi (that is what is written on the dyno sheet for psi range).

Yeehah!!

Marc
DEVEK

John..

Now where is that monkey that pounds his chest? Call it ranting, but you must admit my speculation on the car's power was basically spot on correct. Anyway, I am not one to walk away from a challenge, in person or across the web. I am certain this car left Callaway making 360+ off the crank. The 8 lb pull was with a very rich mixture and 3 degrees out on the timing. That timing was put back in on the 11-12 lb pull and was worth a healthy 20 RWHP.

Keep in mind Lag, the reason your curve is more linear is because the centrifugal develops its peak boost at peak RPM, where the turbos develop peak boost at 2/3 peak RPM (1/2 or less if your setup is perfect). Your power would appear to "drop off" after a certain point with turbos as well, but the mid range would be hugely fatter on torque, no doubt about it. I'm confident my curve is shaped like it is because of the cams in the car. If it was the turbos, the boost would be dropping off. Now it will hold 13+lbs all the way to redline. The RHB-6 is good for 250-300 HP worth of air, so in theory those blowers could support nearly 600 HP if the setup would allow it.

Have any of you guys plotted how much boost those blowers make as a function of RPM? Like, it is 4 lbs at 3000 rpm, 6 lbs at 4000 rpm, so on and so forth? That is why I like the turbos....boost is not attached to RPM, but load.

I'm done for quite a while now.....but trust me, visions of Bastard II are floating through my head. Anybody have a 928 S4 doner car....hmmm there is a rolled one down the street with a good motor....can you hear the gears turning?

Anyway, Lag I am glad to see you are such a good sport, this is all in fun and I do hope you know I am just pulling your chain.... BTW, turbo maps show an efficiency of about 68% where I am running them. Not the best units by any stretch, but they are responsive and get the job done.

John..

Marc,

Yes, the pulls were at 11-12 psig on the dyno. Ironically, the car will make 1.5 to 2 lbs more on the street. Don't ask me why, but it does. It could be a function of ambient air to cool the charge, or more time to get to high boost because of the additional loads on the car. It gets to 11 lbs at about 4,000 RPM....you can see this on the torque curve by the slope of the line.

My ultimate goal was to kiss 400 RWHP, and while that didn't happen I am still very happy with the results. It is already making plenty of power for the street and I don't need to kill myself....jeez as of late all you have to do is drive through Columbus, OH and get snypered...

The officially puts Bastard into the power category with Z06, Old Viper, M5, M3, etc, etc. The real trick is in how stock the car looks, even when you lift the hood. It could use more meat out back, but I like the way it looks so bone stock....sleeper for sure.

Tony

Perhaps your next step, instead of an S4, could be to step up to some bigger or more efficient/modern turbos?

Fastest928

John,
Can you explain why this turbo setup almost doubles your hp, but not a 14 psi boost?

A stock S4 makes about 275-285 rwhp, at the same pr ratios, why does the turbo have a higher hp, even though the torque curve is less than ideal for peak hp?

Marc