I was reading through Excellence about the Brumos fabcars that ran at Daytona and in the article there was a mention that the engine they use is from the GT3 but that it puts out 500 naturally aspirated horsepower. I am wondering if anyone knows exactly what they do to the GT3 engine to squeeze another 125 or so HP out of it?

 

I believe the Porsche DP engine is based on the GT3 RSR engine that puts out 445 HP with the air restrictors mandated by the FIA in GT. I suspect they get larger or no restrictors on the engine in Grand Am, which would help increase the HP. They are also running open exhaust, no cats or mufflers, have a different intake manifold, and a different ECU that remaps the engine for racing and raises the rpm limit to 8500. I know the RSR engines run so tight that they have to get rebuilt after every 30 hours or race time or so. The DP engines may require even more frequent rebuilds to maintain their power and reliability.

Karl

 

I've plugged three tiimes now, but it looks very interesting: http://www.9mracing.co.uk/html/modul...18&quickview=1 not sure if they got the 450....but it is air cooled. After I master my driving skills, it will be either this or a current GT3 depending on bank balance.

 

The RSR use an intake manifold that has 6 throttle control valves - one for each cylinder - rather than the manifold in the standard GT3 which has only 1 for ALL 6 cylinders.
That alone should give you 20-30 hp - at least it did in the 993 and/or 964.
FVD sells the 6x throttle control valve intakes for the 993 and or 964 and they claim 30 hp gains.

I've asked my Porsche mechanics about the manifold, and they do agree that it would add about 25hp, but they said a change in the cam profile might have to be needed.

I've asked the same question on this board and I get the same answers of the Cup cars having to be ripped apart after 30 hrs or so, but I can't see why there couldn't be a happy medium.
There are other road cars running 450-500hp NA and dont have to be ripped down.

Gallardo, 575M, Diablo, Murc.
Is it b/c these cars are running 10, and 12 cylinder motors, less stress on each cylinder?

 

The Brumos cars are running the top spec GT3RSr engines, unrestricted I beleive. However, they are still at a power disadvantage and I think that is really going to show this season. Perhaps there is a Cayenne V8 in their future as I would hate to see them goto Lexus or Mercedes for more power.

My understanding is that the GT3 cup car engines are good for about 75 hours before they need to be taken down. The top spec RSr engines probably need to be freshened every 30 hours or so.

 

These engines all run on at least 100 octane race gas as well, which helps in the HP department.

I think Porsche's lobbying is the main reason that the DP engines are limited to 500 HP. Obviously the big Chevy's can do more than that in NASCAR tune.

Karl

 

The Brumos cars are running top spec RSR motors unrestricted. I heard Hurley say they were making 485HP last year so around 500HP this year sounds right. That is about all this motor will make in current size. It is at a disadvantage compaired to the other V8 DP cars. Porsche Motor sport needs to race a race version of their Cayeene V8 or bump the 3.6L F6 to at least 4L, unrestricted of course. GA used the Porsche engine as a base for power for their DP cars. It was a wrong choice in my book because there is no real room to increase power over time. DP cars need around 600HP to make the fans happy. Now that there are many cars and teams with V8s, GA will cater to their needs and not Porsche. Look for the Brumos cars to run mid pack all year. Porsche Motor sport get your act together and make an engine with MORE power! Porsche fans hate to see our cars get passed!

 

piston velocity can be greater in an engine with more cylinders. greater piston velocity = more hp, but the trade-off is torque.

how many n/a road cars can you name that are 6-bangers under 4 litres that are around 400hp besides the gt3??

 

Curious as to why the Carrera GT engine has not been made available for the DP prototypes?

 

I think the CGT engine would be considered too "exotic" for DP and as KarlS points out above there is a limit of 500HP imposed for the class.

 

Maybe talk to Todd over at EVO to see if he will put the regular 911 supercharger in the GT3. That would be 100+ hp right there.