drcollie

If TPC installed the intercooler, this little dahling is pumping out 475
HP with this conversion. This really is a steal, but watch...no one
will buy it. Hard to sell a modified Porsche unless the mods were put
on at Stuttgart.

With the body kit and Turbo, he's dumped a ton o'cash into this rig. Any of you guys want to rape the asphalt with a proven turbo in a world-class car, here's your chance. He's bleeding out on this one at $ 42 large.... bet his wife doesn't know.

http://washingtondc.craigslist.org/m...639574452.html

Renn 951

So how does this car put out 475 HP at just 5.5 psi of boost? The theoretical max HP at that level (less than 1.4 bar manifold air pressure) is about 405 HP. That's still a damn good number and it looks like a nice car, but what magic is being done to claim a HP number like 475?

renvagn

One of those generous dyno print outs...........................................

drcollie

TPC is well-regarded. I know they do install an intercooler in the front for the 475 HP version. You can read more about it here:

http://www.tpcracing.net/articles/tt...-turbo-by-tpc/

They also offer a non-intercooled variant that 'only' increases the output of the Cayman S by 100 hp.

RollingArt

I'd be afraid that it's a ticking time bomb, waiting to blow!

TPC calls these motors fragile from the factory. Then they add a turbo? Good luck!



Phil

drcollie

Thats why my car doesn't have one. I already bought one new Porsche short block, for my 993 C4S I used to have. Cost me $ 15,000. I'll just keep my warranty on my current Porsche intact - thank you very much - and if I really feel the need for speed get out my BMW motorcycle instead.

ericthepilot

I concur
Bikes do it so much faster, and BMW K1200S really does a nice job ...

cparkin

Our standard turbo makes 420whp. We recently released a 477whp car at 6psi on vp109(had our standard turbo on it for 55k miles before upgrading). It is all real. We have built many in house and shipped the system all over the world. Recently won EVO Magazines Modified car of the year.

http://www.tpcracing.com/articles/th...-cayman-turbo/

Placed 2nd in teh Eurotuner GP(behind a 900hp audi) and this summer we are competing at the Grassroots Motorsports Ultimate Track Car challenge.

We have a number that run DEs and one that is being run in the 1 lap this year.

Our shop car had more than 60 track days at daytona, summit, the glen, vir and .... Over 2k in dyno miles and 15k street miles. Never had a hiccup.


If you are going to be at hershey, we will have our Boxster Spyder there with the turbo sitting next to it(finishing our Gen 2 tuning).

Stop on up for a ride

Renn 951

420 WHEEL horsepower? That would mean around 495 engine HP. How can you get a 67% increase in HP over stock just by bolting on a turbo that increases airflow by only 37%? The power increase has got to be proportional to the increased air and fuel input, all other things being equal.

Did you mean 420 engine HP? That would seem to be in the right ballpark. And it would still run away from GT3's in any event!

Alan C.

My take would be what did the car make at the dyno before and after, same dyno. The details are in the delta.

cparkin

Yes, 420 Wheel HP... you live close enough! And you still have your 987S, right? Come on up and see for yourself.

A 3.4L 987S car traditionally makes 265whp on our dyno... We deliver standard Turbo cars at 5.5PSI and at roughly 410-420whp.

There is one large factor you are not considering... ... High compression coupled with low boost pressure is comparable to low compression with high boost pressure.

Vu and Manny are coming up in a week or two to try out our new Box Spyder and they will be producing a video on our Cayman Turbo coming early next month.

Like i said, you are quite close. Feel free to come up and experience it for yourself.

cparkin

I would post links but we are not a sponsor here... so if you are interested go to the website for multiple dyno sheets.

Renn 951

Casey: if your chassis dyno is only showing 10% drivetrain loss on a 295 HP car that would partially explain generous wheel HP results. But still, at 5.5 psi boost you are only increasing air flow into the engine by 37.4%. Multiply your 265 WPH number by 1.374 and you get 364 WHP. All other things being equal, the increased power HAS to be proportional to the boost increase. Even allowing for a little richer air-fuel ratio under boost that would only give you another 10-20 HP - no where near the 410-420 you are claiming.

Compression ratio has nothing to do with it because you haven't changed the compression ratio from what you started with. You are taking a stock engine with a known HP, bolting on a turbocharger that gives a fixed increase in energy input to the engine, and you are claiming a resulting power output that is greater than the sum of those parts. How can that possibly happen? I'm an engineer and I've got to tell you the claimed HP numbers seem to defy the laws of physics. And it's not the intercooler that's creating this magic, because all that does is cool the heated compressed air coming out of the turbo back down to a point where you have a chance (maybe) of achieving the max HP calculated above.

Can you please ask one of the TPC engineers provide an explanation?

cparkin

There are a number of factors that you arent considering. I am not an engineer but I will add some bits of info. Turbocharged hp can not be calculated by a simple equation. An equation doesnt take into effect the volumetric efficiency of the engine, air density, the size of the turbocharger(heat dissapation), octane level and many other factors. You are saying that all engines have the same volumetric efficiency and that is not the case.

This is what volumetric efficiency is...

http://en.wikipedia.org/wiki/Volumetric_efficiency

The power has been proven world wide

Here is an article from 911 and porsche world.

http://www.tpcracing.com/articles/th...-cayman-turbo/

That car was dyno'd at REVO

Here is a scan from Eurotuner that shows their 3rd party dyno rated the car at 422.39whp...

This is a proven world wide system. We also use a dynojet dyno where constants cant be changed... That is why Nascar/GrandAm uses them for benchmarking.

Renn 951

Casey:

Of course the actual power can not be determined by one simple equation, but the simple equation I gave you earlier provides the MAXIMUM power your turbo is going to provide, all other things being equal. Because the system isn't perfect and in real life you will see less than 100% efficiency, the real numbers to expect will be LOWER.

Now, please read the Wikipedia link you provided and tell me what you did to the engine other than add the turbo that improves the volumetric efficiency. Did you port the heads? Change the intake plenum? I don't see modified heads or a new intake plenum included on your website as part of your kit - did I miss something and you include these items? The only change I see that affects volumetric efficiency is adding the turbo and we've already addressed that with the increased air flow and the increased fuel flow providing a MAX power that is much lower than what you claim.

The link you provided from your website with the UK article on the turbo Cayman is interesting - it says that system was developed by Parr. Is that your turbo kit they used? If so, they don't give TPC any credit for it. However, I do see that the Parr kit includes a modified intake plenum - which as discussed above could certainly increase the volumetric efficiency and lead to a higher HP number. Is the modified intake plenum part of your kit? I don't see any mention of that on your website.

The scan you provide from Eurotuner is also interesting. It says that in addition to your turbo kit that car also had other engine and drivetrain mods (BBI undertrain pulley and lightened flywheel) which would result in increased dyno HP numbers. Are those part of your kit? Because the HP numbers you are claiming are the same as what they show for the Cayman with the additional mods done.

So, back to my original point - unless your kit includes more than it appears (i.e. just the turbo, injectors, intercooler, and exhaust) there is no way you can get the numbers you claim on a properly set up dyno test. But if there is more to your kit than it appears (i.e., other engine mods, drivetrain mods, etc.) then of course you could get more. You are giving me as "proof" dyno numbers from cars that have extra mods that I don't see as part of your kit. What exactly is included in your kit?