98993c2s

Having been personally involved in several Porsche supercharger and turbocharger developments and installations I'm quite familiar with dynos, and performance, and factors the must be taken into account. To be quite honest, I did my own math, and things didn't add up. That's when I googled and found the supercharger horsepower calculator, and the results of that matched my estimates.

Fuel mapping and timing adjustments are necessary to prevent detonation and provide the necessary fuel but in and of themselves they do not provide the additional power to hit your numbers; in fact the retarded timing takes power away. An engine is an air pump; there is something called the laws of physics whose laws can't be violated...and there is simply no way that 4psi (27% more air presssure) can possibly create 49% more peak hp. Period. It is physically impossible, no matter how close to perfection the rest of the system operates or is designed. Even if all the fuel required is available, plenty of fuel pressure, larger injectors, adjusted maps, the works...it won't happen.

Your trade secrets or even the style of blower does not have to be revealed in order to respond to these points.

Bottom line: I'll wager $1000 (or better yet, I'll purchase a kit) if you can get 49% additional rwhp with 4psi, with any blower or turbo. Build it and we'll see.

1999Porsche911

I agree with Robert. There is no way a 4psi boost will produce a 49% increase in HP at any RPM. With a roots style blower, you will have a nice increase in the bottom end, but no where near 49% more. The boost will only deliver so much air to the cylinders so you are limited in the amount of fuel you can map. Increase your boost to 6 - 7 psi and you might get there.

graham_mitchell

I think Stephen's claims are achievable if it's done right. TPC claims 50% more power from 5 psi and I believe there is room for improvement over the TPC kit such as the use of larger injectors rather than the 7th injector. There is also untapped potential which can be realised with the right engine management. Just look at what Motec can achieve even on a NA engine! Let's wait and see what Stephen comes up with.

1999Porsche911

Th stock engine is mapped to maximize the power based on the amount of air the intake can take in. The addition of 4 psi of boost and the appropriate amount of fuel WILL NOT give a 49% increase in HP regardless of whether you use bigger injectors or tripple the number of injectors. It simply cannot be done, period. You will not start to get close to a 50% gain until you get the boost higher than 6 psi and even then you would need optimum tuning of all other engine componants as well as proper management of the air temperature entering the engine..

There is no doubt that the 4 psi boost wil provide some nice power, but a claim of almost 50% is simply not possible. With a roots blower, most of your increased performace will be in the lower end of the curve. This is not based on opinion, but based on more than 30 years of experience with building SC engines with every type of blower. The only way you can increase HP with a combination of fuel and air in a properly tuned engine is to increase compression. 4 psi on this engine doesn't come close to giving you the effective compression ratio needed to really pump the added fuel into the cylinders. The car would be fun, but sure wouldn't be 50% more powerful.

graham_mitchell

1999Porsche911, you have the experience which I do not, and I acknowledge that.

Stephen did say his figure of 4psi was a guess, to be fair. The TPC kit has shown that 50% more power is achievable with 5psi, so I have no doubt that Stephen could match or better that power increase using a safe level of boost with a more accurate A/F ratio and more sophisticated timing management and possibly lower charge temperatures. Sorry if I wasn't clear.

All this guessing gets us nowhere. I hope Stephen can get an engine on a bench and provide us with some hard figures.

1999Porsche911

Also, be careful of claims of the dyno. You most often notice that the "pre mod" dynos are run during the hottest part of the day and the "after mod" dynos are done at the cloolest part of the day. This drastically effects the HP. The dyno also is effected by variables entered by the operator. Some will adjust for altitude, atmospheric preassure and even how much beer the operator drank the night before.

I don't bother with dyno's anymore. If you are happy with your car's performance, it doesn't matter what a dyno says. Take the car to 10 different dyno's on the same day and you will get 10 different readings. They are only one tool of many tools necessary to determine perfromace increases. I would rather be able to get to 100 mph faster after a mod rather than see a power increase on paper.

98993c2s

For what it's worth, TPC can't get 50% with 5psi, any more than 4psi will get 49%. It's just physically impossible. Don't believe every number out there.

TheOtherEric

To be honest, I wouldn't want 50% increase in hp. I'd be happy going from 230 rwhp to 310 rwhp (35% increase). Why do I say this? Because it would run cooler (less risk of detonation on hot days), would put less stress on the engine and drivetrain, yet would still give you huge bang-for-the-buck. It sounds like this could be done with 5 psi boost.

Like others, I hope to hear more details on this kit; not the proprietary stuff, just the basics: type of compressor, type of intercooler/aftercooler, expected shape of torque or hp curve, expected cost.

98993c2s

I agree Eric. 35% is a nice boost...we just got done with a similar project, and it turned out very well...the goal isn't to provide a Viper killer, just to get some decent additional performance.

For me, I'd like to get enough out of the 993 to compete on par with a 997.

ESL

Stephen,
I am interested in theory but the devil is in the details. I would need to know how much it would be for a '96 and how much installation would be. Also, would you help my local shop (if he could do it) with the install?

PorschePhD

Robert,
I respect your stance as well as 99Porsche and you are allowed the doubts. Best part of this board. When you asked what the goals were I gave you a loose estimate.

You can debate whether 4-5psi will yield the results I am estimating. No one has still addressed the issue of volume and what the VE is of the motor. If you increase volume you increase the % of air. I crack up when people only talk about pressure only. You can make 2 bar from a K16 and you will loose HP, not gain it. It really doesn't matter until the car is complete. I am far less concerned about the boost as I am the overall AFR and CCT.

The best part about building kits like this is the ability to make what is wanted/needed. That was the whole point to the post to see what the interest is.

Sorry I am not the personality to start posting mathematical equations to prove my estimates.I certainly can and have them but I would rather put them into action and see where the chips lay. A wager is not a bad idea sir Theory and chit chat on the boards is fun, but I spend the better part of my day on the dyno or building forced induction Porsche motors. So I have a little idea of we what we can make Please don't take that the wrong way. It is not a snide remark.

One last note, dynos should not be used as much as they do for bench racing or selling tools. The sad fact is the public request these numbers and we have to provide them. Two dynos almost never show the same thing and people never control the environment well enough to really determine the gains or losses on the dyno. Some dynos are better than others, we have a Mustang AWD in house that we tune with. The curve is what we are looking for. I am not interested in peak power, I am interested in overall gains and drivability. That is key. My personal car makes 744RWTQ from apx 4K to 7K. Now that is drivable.


ESL,
I work with everyone. If it is a shop great! In some cases I will even fly out to work with the ship if need to be. We have done several TT conversions and SC for the 996 this way. I don't mind if time permits.

Total911 Magazine

Stephen

Good luck with the project - your post will sort the tyre kickers/wannahaves from th 'doers'. Hope it goes really well.

PorschePhD

Same to you and your new venture!!! BTW sign us up would ya?!

98993c2s

Stephen, I guess my primary focus on this project is not whether it will work (it will); not whether it is a good idea (it is); but whether it will live up to the promises you have made.

In the first post you said:

"Those of you that know me know that my attention to detail is my claim to fame. The system would increase HP apx 49% over stock."

These two sentences to me do not come across to me as a 'loose estimate.' 49% sounds like a pretty sure number to me. That 49% figure is what first grabbed my attention.

"Wow, he's predicting accuracy to within 1%!" That's what prompted me to ask what boost figure.

A loose estimate would say '40-50%' or 'over 40%' or 'somewhere in the neighborhood of 50%' or something similar. But it wouldn't say '49%.' 49% sounds exact...

Combine that with 4psi which won't come close to increasing hp anywhere near 49%, and I am confused as to this claim of attention to detail.

Lastly, explain what you mean by volume. By volume are you referring to cubic centimeters of displacement? That's the only volume I know that matters. If there is another, I'd love to learn more about it. And I'm not being sarcastic here...I'm truly interested. And yes, I'm all for mathematical formula; I was a math and physics major.

1999Porsche911

The is no way to increase the volume of air in the cylinders without compression unless you're going to bore them out or put a shorter crank in..