3.8 Whipple vs Ported Roush 2650

[Autopart101]

I recently pushed a Roush 2650 to the limts. Ported inlet and outlet let 103mm TB on a 2.7 pulley. Car made 17lbs Boost and 940whp. Sold the Roush to a member on here and installed a 3.8 Whipple. Had read that a 3.5 pulley would make 19-20 Psi boost on a stock lower. Thats not true in my case. 3.5 pulley made 14.5-15psi Boost. Whipple made 922whp. Note the Whipple pull has a full 3 inch Ex as the Roush had a stock cat back. Whipple made great number for low Boost Dyno sheets attached.

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[robvas]

Probably even better with the 3.0 at that power level

 

[Autopart101]

Probably even better with the 3.0 at that power level

Plan is new Short block next year and more boost.

 

[Pistol_91]

Which whipple?

 

[Autopart101]

Which whipple?

3.8 Whipple

 

[SolarFlare]

A worked 3.0 is all you need for the big power street guy.

 

[Autopart101]

A worked 3.0 is all you need for the big power street guy.

Got a great deal on a 3.8 kit. I just thought at any given pulley size the 3.8 kit would make more than 1 psi boost more than a 3.0 kit.

 

[Timbuck]

Does whipple have a graph of CFM difference between the too ? Also i wonder what the HP cost of spinning the bigger blower ??

 

[SolarFlare]

Got a great deal on a 3.8 kit. I just thought at any given pulley size the 3.8 kit would make more than 1 psi boost more than a 3.0 kit.

my guess it’s probably not. I’d say on most pullies the 3.8 will make more boost and similar power. If you can’t process the air then there’s no use for it

 

[Autopart101]

Does whipple have a graph of CFM difference between the too ? Also i wonder what the HP cost of spinning the bigger blower ??

My guess is 3.8 makes more power with less boost. 922whp on 14.5 is very efficient numbers.

 

[Autopart101]

my guess it’s probably not. I’d say on most pullies the 3.8 will make more boost and similar power. If you can’t process the air then there’s no use for it

Need to find out what 3.0 kits are making on 14.5psi boost. My thought were gen 3 engine on 16psi boost makes around 900whp.

 

[engineermike]

Something isn’t quite adding up on this. The 3.0 on the 3.5 pulley makes 14 psi so it doesn’t make sense tha pushing literally 25% more air into the engine barely makes more boost.

Couple of other data points….drp has a video out there of a gt500 making 1000 rwhp using the 3.8 Whipple on the 3.875 pulley, and he states it’s making 15-16 psi. Obviously, the 3.5” pulley should make more boost, especially considering the smaller displacement engine with smaller heads and valves.

Next if we do the math the 3.8 Whipple on the 3.5 pulley should move 10% more air than the 2.65 Roush on the 2.7 pulley. Barring either blower being wildly inefficient, 10% more air should be 10% more power.

I’m wondering if ambient conditions might play a part in this. I know NC has been pretty miserably hot lately and the Roush was dynod last September but I don’t know exact conditions of each. The correction factors really aren’t that accurate.

 

[Autopart101]

Something isn’t quite adding up on this. The 3.0 on the 3.5 pulley makes 14 psi so it doesn’t make sense tha pushing literally 25% more air into the engine barely makes more boost.

Couple of other data points….drp has a video out there of a gt500 making 1000 rwhp using the 3.8 Whipple on the 3.875 pulley, and he states it’s making 15-16 psi. Obviously, the 3.5” pulley should make more boost, especially considering the smaller displacement engine with smaller heads and valves.

Next if we do the math the 3.8 Whipple on the 3.5 pulley should move 10% more air than the 2.65 Roush on the 2.7 pulley. Barring either blower being wildly inefficient, 10% more air should be 10% more power.

I’m wondering if ambient conditions might play a part in this. I know NC has been pretty miserably hot lately and the Roush was dynod last September but I don’t know exact conditions of each. The correction factors really aren’t that accurate.

Also- Roush 2.7 pulley is stock cat back. Whipple 3.8 is full 3 inch cat back. Still making 922 on 14.5 is pushing turbo numbers.

 

[engineermike]

I don’t think the timing was dialed in all the way on the Whipple 3.8. Not 100% sure but I think there a bit more power in it.

 

[Autopart101]

I don’t think the timing was dialed in all the way on the Whipple 3.8. Not 100% sure but I think there a bit more power in it.

I spoke to a few people that have the 3.8 Whipple kit and know it well. 3.5 pulley makes 18-19psi boost with a stock lower. With the tune not 100% done. Looks like we are heading to 18-19 psi Gen 3 numbers.

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