Here's a dyno done today with the SFR420 kit (with the HR 2.5L short block) at 15psi boost.

Note that this result is only a preliminary dyno run. We're still running the stock intake & stock intercooler which are presenting a restriction for this motor.

The max boost on this kit was 15psi, and we're still running the stock DME chip (so that we could use pump gas) with was cutting off the power at a "mere" 6250rpm.

I estimate that w/o the rpm limiter, this combo would pick up another 5-10HP at the wheels over an additional 500 or so rpms, with the same 15psi (1bar) boost.

<img src="http://www.tonygarcia.org/951_dyno_4_17_2003.gif" alt=" - " />

Damn I hate rev limiters!

 

Go Turbo Porschero! <img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" />

Great numbers. Are you sure the DME chip is stock? They're programmed with overboost protection which wouldn't allow you to reach 1 bar positive pressure.

 

PorscheG96

I'm sure the DME chip is the stock one.

It's the KLR chip that has the overboost protection built in.

As far as the "Porschero" goes... pretty funny... The race shop I dyno at is a Honda tuner shop. They laugh at me showing up in a Porsche! But... you can rest assured I hand it right back to them!!!!

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by TonyG:
<strong>I'm sure the DME chip is the stock one.

It's the KLR chip that has the overboost protection built in.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Gotcha, that makes sense.

The horsepower curve looks really good...what do you think is allowing horsepower to keep climbing versus falling off after the torque begins dropping? More specifically, what's different about your car that keeps the torque from dropping off so quickly in the midrange and upper RPM's?

 

PorscheG96

The difference is substantial.

The SFR420 kit takes a completely different approach to HP.

They say that there's HP with rpms. There is. So the trick is to get a setup that will develop the necessary rpms to make additional HP.

The one thing that I've noticed through the years with dyno runs (various cars with various configs) and other list members dyno sheets is that no matter what the HP, whether it's 275HP to the wheels, or 475HP to the wheels, the dyno curves look identical (just the HP/TQ curves are moved up or down the graph). Power is always flat by 6000rpms (in most cases before that).

There are multiple reasons for this:

1. Cam timing/configuration
2. Exhaust port flow
3. Exhaust back pressure between the head & turbo

These turbos with the KKK hot side or the Turbonetics KKK compatible hot side develop way too much back pressure.

It's this high back pressure that keeps you from running a real good cam.

So the first step is to eliminate the back pressure.

Then, you can run a big cam effectively. If you have a lot of back pressure, you can't have any overlap, which kills the top end.

The next step is the header (4 into 1) which is by design, a top end HP maker, where the factory Tri-Y header is designed for midrange power.

Then finally, the head. Power is always made in the head. The head is based on a normally aspirated head. Why? Because you can't port the exhaust of a turbo head (ceramic liners cast in).

The exhaust port on my head are huge compared to a turbo head (the intake ports are extensively ported as well, but running stock valve sizes).

See the trend? It's all in the back pressure... or lack of it.

This is why the TQ is less than the HP, which is not typical of a 951 motor at any power level.

There's no reason to have this huge TQ for a road race application. I can't get it to the ground as is at lower speeds. Given this, I wanted to have HP to 7000 rpms (which this car should do if the damn rev limiter didn't cut off all my fun!!!)

 

Now the only thing left to do is to dump the stock intercooler in favor of a less restrictive design, and to dump the stock intake manifold (which flows no where near what intake ports flow)

 

Ok, so you have all the above mods done to your car? Nice setup, it must have cost you a $ or 2.

Since you requested I do a dyno run at 1 bar boost, may I request you show us one at 22-24psi boost?

Also, you were talking about reliability? How reliable is a 951 engine when you rev it above 6400rpm? But hey RPM makes HP doesn't it.

 

fast951

There's no way I'll do a 22-24psi boost run in this car with the stock intercooler. I wouldn't do that high of a boost run even with the new Spearco intercooler either (which I don't have yet). I'll probably limit my boost to a "mere" 18psi.

18psi is the limit of what I consider safe in this engine for sustained periods of time. And since my car is built to run on a track (and street), I only intend to tune it for sustained operation.

I'll do a 18psi to 18psi run though.

Also, these engines prepared properly will run all day long at 7000-7200rpms. Above that, then we're talking a different story.

 

TonyG,

Please read my post on the other thread.

Also, are you sure the 951 engine can run at 7200rpm. Do you really think the lifters can perform at this rpm? Hey, your main idea is to run 1 bar boost which is the boost level that most people will run on the street. It makes sense, I agree with you.

But when you make the statement that the engine can run at 7200 rpm, I wonder if you have done your homework. Unless a well prepared head means SOLID lifters, which is something the average 951 owner who wants to run 1 bar boost will not consider converting to.

For your information, the stock lifters struggle real bad around the 6700-6800rpm... But hey, don't take my word for it.

Tony, thank you for your time. I enjoyed our brief conversation, and I truly wish you the best of luck with your kit. The floor is all yours, I'm out of here!

 

fast951

Yes I'm sure about the rpms. I didn't say that you could do it with stock lifters and stock valve springs though. I said "properly prepared". That means doing what you need to do so that you don't float the valves.

You also don't have to have solid lifters to run at 7000-7100rpms with the correct valve springs (and modified lifters). I know this for a fact. Before I installed the stock DME chip (which required race gas) I ran quite often to 7000-7100rpms.

Above that, and you're getting into solid lifter territory for sure.

 

fast951

I also left out titanium valves which weigh a LOT less, and as a result will not float as early.

Combine that with modified lifters and race valve springs, and you can run pretty high without any danger of floating valves.

 

Tony,

Let's assume that you can modify the head assembly to handle 7200rpm. I would love to see the color of the oil after you run the engine at 7200rpm for a sustained period of time. I think the word I'm looking for is "Oil Foaming"..

Obviously we have different views on how to make things work. I believe in keeping it simple, no exotic parts. I also believe that torque wins the race, but HP sells.

Again thank you for sharing your points of view with me it has been interesting. I'm out of here.

 

i've done alot of research on the TQ / HP selling in motor building lately.

TQ only moves you below 5,252k. On the track, you spend a considerable amount of time above that mark.

 

Why would 7200 rpms induce oil foaming? Particularly with a properly setup oil cooler system. It's not like a number of cars in the world don't run significantly higher than 7200rpms...the issue is cams, valvetrain, and breathing. If you can get the flow, the cam, and the valvetrain to handle it, there's no reason it wouldn't work effectively. My personal opinion is I'd rather make torque low for street use and not subject my con-rods to the higher stresses of upping the rpms, but for a track, I can completely see why Tony is looking that route. It doesn't make sense to me to suggest only 7200rpms as unsafe, as it's been done in a multitude of cars, you just have to prepare the top end properly as Tony suggested.

 

The high rpm causes the crank to create the foam, windage.