At Daytona...Porsche DP's running a 3.8L normally-aspirated motor -
looks like that's the GT-3 motor guys.

 

ENGINE:
Six-Cylinder Boxer Porsche 3795 cc –
76.4mm stroke, 102.7mm bore
Horsepower: 510 @ 8500 rpm
Torque: 435 N/meters @ 7500 rpm
Max RPM: 9000
Cooling: Water Cooled
Intake System: Six Individual Throttle Valves
Fuel Injection: Sequential multi-point Bosch MS 4.0 system with ignition control
Lubrication: Dry Sump with Heat Exchanger and Mobil 1 oil

 

They are probably running 4 liter engines that (unfortunately) don't really share any parts with the street motors.

 

Hello? I didn't say 4.0L, and that's not what was listed
on SPEED when they showed the specs. NOT 4.0L, 3.8L,
at 2150 lbs. It was stated more than once, and the
specs for all the chassis-engine combinations for the
DP class were listed..and I'm sure the Grand Am website
will say the same.

 

Not 4.0l 3.8. The specs I listed above came off the Alex Jobs web site. that is the motor for the #23 car

 

That is why I also posted the link to the GrandAm competition bulletin for the Rolex24 with the engine size (3.99l) listed on page 2.

 

Interesting that this conflicts with AJR website about their **own** car.

This is a 3.8L Flat 6 motor from what I know also.

 

I think the engines are sealed and basically delivered as-is and untouched from PMNA to Daytona. Its possible that between the time the AJR website was last modified and possibly winter testing at the beginning of the month and now, that adjustments were made to make the Porsche engined DP cars more competitive and that is reflected in the official bulletin that I posted the link to? The cup engines are the same way, even though you might own one you can't open or touch it or do anything to it in any way. You install it and go.

 

That is the maximum allowable size that is legal. THey can run anything they want lower than that and with unlimited rpm.

 

the regs just mean that they could go the that size. Since the #23 car and the others stayed at 3.8 with could carry less weight and had no rev restrictions. The V8 had more weight and were limited

 

The things done to make the Porsche teams more competitive had more to do with the chassis than the engine.

 

The exact wording from the DP Class Engine List is as of 11/01/05, "PORSCHE 3.99L GT3R Flat 6
Up to 3.99 liter displacement with unlimited components. Engine to Transaxle adaptor with 1 to 1 ratio allowed approve supplier TBA. Maximum fuel pressure 8 bar (116 psi)". There is nothing about extra weight or rev-limiter restrictions. We're arguing about .2 liters but in any case if the rules say Porsche engines can have 3.99 liters than every engine from Porsche will have .199999999 liters more than a 3.8 liter engine and not a cubic millimeter more or Porsche would not be allowed to run titanium connecting rods. (anything with 4 liters or more can't run titanium rods)


Agreed

 

I think that DP Class Engine List doc is stating that the class is UP TO 3.99 liters. The AJR car is a 3.8 liter.

The AJR car had the advantage of something like 120 lbs less mass due to the rules for a small displacement engine, and with the "drop-gear" for the transmission, the whole powertrain had a lower center of grav (as did the Brumos car).

 

The Porsche DP engine is 3.99 liters.

 

So the Jobs web site is providing incorrect information as to the specs of their motor? Would this be intentional or they do not know?