03 Twin Turbo Cobra Dyno Results

[na svt]

I would have expected the hp to peak at a higher rpm with the short runners of that intake. I wonder how that intake compares a ported Mach intake in power production.

 

[imaboa]

We were talking about that last night.

My guess is one of two things:
- there's too much plenum volume for the power level we're at right now
- I've got 4psi springs in the WGs, could be enough back pressure in the exhaust to make them leak a little, causing the turbo speeds to be a little high. Although theres only an air temp difference of about 25degF from the start of the pull to the end.

 

[Parts-is-Parts]

Im no expert, but why in the world would you have less timing in one cylinder as opposed to all the rest.

Hot or not, that just aint right.

Looks great I might add!

 

[na svt]

Im no expert, but why in the world would you have less timing in one cylinder as opposed to all the rest.

It's very right and it keep the temperature in #8 cooler as it's the cylinder/piston that is first to be damaged by excessive heat.

We were talking about that last night.
My guess is one of two things:
- there's too much plenum volume for the power level we're at right now
- I've got 4psi springs in the WGs, could be enough back pressure in the exhaust to make them leak a little, causing the turbo speeds to be a little high. Although theres only an air temp difference of about 25degF from the start of the pull to the end.

The cams are much better suited for supercharger applications but they should still make peak at a higher rpm that what is on the graph, even stock cobra cams will peak at 6200 with a stock intake. We just put a ported stock ported intake (replaced a Sullivan) on a twin GT35 04 which also had GT cams. It peaked at a higher RPM than the yours and with the Sullivan the peak was even higher. The stock intake provided boost much quicker and a had better power curve since RPMs were kept to a max of 6500. Those short runner intakes look cool but don't really work too well for sub 7k combos.

I'm not sure plenum volume would reduce the RPM at the point where peak occurs by that much.

 

[imaboa]

Im no expert, but why in the world would you have less timing in one cylinder as opposed to all the rest.

Hot or not, that just aint right.

Looks great I might add!

An 8 Cylinder motor is really (8) 1 Cylinder Engines put together, each with their own fuel and ignition timing requirements for best torque output. If you have the power to adjust each cylinders fuel and timing definitely do it, its going to last longer and make more power than the guys that can't :rolling:

 

[imaboa]

The cams are much better suited for supercharger applications but they should still make peak at a higher rpm that what is on the graph, even stock cobra cams will peak at 6200 with a stock intake. We just put a ported stock ported intake (replaced a Sullivan) on a twin GT35 04 which also had GT cams. It peaked at a higher RPM than the yours and with the Sullivan the peak was even higher. The stock intake provided boost much quicker and a had better power curve since RPMs were kept to a max of 6500. Those short runner intakes look cool but don't really work too well for sub 7k combos.
QUOTE]

What kind of dyno? Inertia or like a Mustang - just out of curiosity.

What is the limiting factor on these motors as far as rpm's go? Is it the cam followers, or lifters or? I was uncertain as to how high we could rev the motor.

 

[woodboy25]

where you get the nice intake from sweet

 

[evil04svtcobra]

engine bay looks very impressive! great build, and tune!