If they recommend a lower level of boost for the track, just get the chip switch and have them program a track setting for you.

Cheers,

 

why not simply adjust the boost from the wastegate?

my car puts out over 700hp at only 1.2 bar.

I think this is reliable enough for the track. We've done lotsa canyon driving and track time with no major problems.

 

For reference, a Ruf 993 Turbo R does 128 MPH ET on the drag strip with 93 Octane and a soft 3000 MPH launch. The Ruf 996 R Turbo is even faster (550 HP version).

With 100 octane, the 993 Turbo R will be about 3 cars ahead of slightly modified 500 HP Vipers at 100 MPH from a dead stop, and over 10 cars ahead by 150 MPH. With 91 octane, it's about 2 cars ahead to 100 MPH, and about 5 cars ahead by 150 MPH. I've repeated these tests many times.

A Ruf 996 R Turbo with 550 HP should be as fast or faster with 91 octane due to it's centrally-mounted spark plug (i.e., the 993 TT cars need dual-plug to get 996 performance at this octane).

My only comparison with the Evo Stage 4 was via accelerometer tests. Here, the Stage 4 was faster up to about 100 MPH (probably due to the variocam and more aggressive start), after which the 993 Turbo R would pull ahead (probably due to it's better matching of engine Torque curve to gearing).

One more piece of info: a board member posted a 0-100 of 7.1 seconds for a Ruf 996 R Turbo 550 HP. This is nearly the same as the Enzo, with Turbo lag! I would suspect that the Ruf R Turbo (550 HP) will easily pull ahead of the Enzo from 20 MPH or higher.

Personally, I'm waiting for Porsche to put a V10, V10 TT, or a V8 TT in a 996/993 style body. Then the Turbo will easily walk past all competitors, just like it always did up to 1996 or so.

BTW, Vipers with superchargers will hit 150 MPH ET, and TT Vipers are even faster. It's hard to compete when you're starting with 8-liters!

 

Hamman -

With all due respect, I think that canyon driving is different than running on a road course. On a road course, you are flat out on the straight away, lap after lap, for an extended period of time. This really does nasty things to most highly boosted street motors. I can't tell you how many highly boosted cars I've seen blown up while instructing at open track events over the past 7 years. I've lost count. Even for those that don't go catastophically, there's still the issue of the increased wear and tear from running 75% more boost than the car was originally designed for. I just don't think it is a wise idea. But, I'd welcome a dissenting view from one of the tuners on the board.

A week or so back CJV and Todd were in on a thread related to whether or not an EVO stage V (or was it 4?) would last for a 24 hour race. CJV said no way period. Todd, who I think was correct on this issue, said it would "with internal mods". While running open track events is not as tough on the engine as a 24 hour race, multiple open track events ultimately will be as damaging to your engine. The cumulative wear and tear will eventually get to you.

Let's say the rebuild time for a bone stock 996TT that races in a stock class, sprint races only (no enduros), is 75 hours. (I don't know this, I'm guessing. Someone should correct me if I'm wrong.) Then I'd be willing to bet that the rebuild time for the 700 HP car with no internal mods is substantially less - more like 20 hours of road racing time (or less).

Disclaimer: This is all based on general knowledge of turbo and other race cars. I am not an engineer (just a racer) and I am not a Porsche turbo expert like some of the others on the board. But, I personally would not run my car in open track events at full boost. I'd turn the wick down a bit (using a lower boost map on the chipswitch).

 

My EVO Stage4 accelerometer data is at http://www.986host.com/gallery/rmrmd1956/Image1

 

How does this compare to what you would get at a drag strip? I think, as I recall, a drag strip time will be slighly lower than the accelerometer time. But, top speed probably is not affected?

 

racer63,

I believe a stock 996TT runs 0.8bar of boost, which means I am running only 50% higher. X50 runs 0.9bar and GT2 runs 1.0bar. WIth these figures, I am running 33% and 20% higher, respectively.

So is my car really that highly boosted? Especially with the addition of a secondary fuel pump providing more fuel with the higher boost? I don't think so.

My mechanic thinks with proper maintenance, this motor should last at least 60-80,000 miles before a top end rebuild, since he says the bottom end is bulletproof.

When the time comes, I will strengthen the internals and do something fun, like a GT3 head.

Maybe I'll even do this sooner than later...

 

Bill S.,

Look forward to meeting you and your wife soon. I think it may be time for a Palomar get together in October.

I was watching this thing yesterday on Julian apples and it makes me want to go back to Julian and get some of that apple pie and buffalo burgers.

I am going to make you a believer in Protomotive! I think my car can out-pull the R Turbo, hopefully I will get a chance to compare one of these days... I am sure Todd @ Protomotive is curious too.

 

FWIW --

"{the 959} two turbochargers and two intercoolers boost the flow of the fuel-air mixture, which is pumped into the cylinders at a maximum pressure of 2.0 bars at under 4300 RPM and 1.9 bars at even higher speeds..."

Is this the same boost figure you guys are referring to? A 959/961 engine ran 24hrs no problem. The 961 was 640HP at 7500RPM.

 

Hamann7,

I'd love to get together to see your Protomotive. Email or call me if you would like to do something this month. If you'd like, we can also rent Willow. I think it's under $2K for 4 hours.

 

Deanger,

Quote from Porsche expert Bruce Anderson:

... a 935 that ran 24 Hour races at either Le Mans or Daytona would require a complete engine rebuild after just one weekend of racing. The pistons and cylinders would be worn out and often the cylinder heads would require replacement as well. This was with special engines for endurance racing and limiting the boost to 1.2 to 1.25 bar for these long races...

Also, the 959 boost was often quoted with the additional 1 bar for ambient atmospheric pressure. So "2 bar" really means "1 bar" in today's language.

By the way, the stock 959 runs slightly under 1 bar with 8.3:1 compression (I think the car's HP may be down a bit from it's 450 bhp DIN rating with 91 octane). With good fuel, the wastegates should keep boost to 14.5 psi up to 4300 rpm, and 13.0 psi above this to prevent detonation (assuming the car is factory stock).

 

cool.

 

LOL I am underneath my car at least once per day adjusting the waste gate, which is modified to start with. Bigger iconnel unit...

 

Hi Hammann -

I think that the wording in my first post was sloppy - my bad. By referring to a "pct of stock boost" I think that I consused issues. The real issue is the volume of air that is being forced through your engine. If a stock GT2 puts out 480ish HP, and you're putting out 700ish, then you're approaching a 50% greater volume of air/fuel mixture through the engine. There's no other way around it. And, comparing to an X50 or stock TT, the increase is even greater. (This occurs because your turbos apparently move more air than a stock GT2 turbo, which is a good thing HP-wise, but does put internals under greater stress.)

Highly boosted, no. More highly stressed than a stock TT, X50 or GT2, yes. Sorry, my bad for speaking too generally before.



I think that's probably do-able with proper maintenance, cool down, and no road racing. Of course, it's an empirical question and we won't know the answer until enough of us try to reach that mileage level.

Well, if you do, let's hope that it is by choice and not by misfortune.

Hope to run across you in the canyons some day in the not too distant future.

Cheers,

 

That looks like an excellent data logger / accelerometer. It appears to beat my G-Tech Pro all to hell. What equipment are you ysing here?

Mike