What kind of fuel pressure are you higher HP guys running (500HP+) on your 24vavles? And can anyone tell me the max inlet pressure of a VP44?


Thanks
Lynn

 

No less then 8PSI WOT is acceptable of any trucks 300-500 HP

 

ok.. would more pressure equal more HP? I watched two truck with:

- 2002 6speeds
- edge comp (no drag)
- stock turbos

differences :
- truck A had BDIII, -8an lines, 18-22psi and put down ~410rwhp
- truck B had supermentals, -6an lines, 9-12psi and put down ~370 rwhp

??? can anyone help me with why truck A was ~40 hp higher?

 

Fuel pressure probably played a part in it. I can tell you right now that both need new turbos cause I have feeling they aren't getting enough air. Did they have any intake modifications (Scotty 2, BHAF, AFE Mega Cannon, etc.)?

 

sorry yes.. both had AFE mega cannons..

 

Then I'd say FP was the main part. I know Rod was saying that with trucks over 400hp, if they could keep above 13 psi in FP at WOT, they would see a 1-3 psi increase on the boost. They guy with the supermentals might also be choking his engine down. Those injectors put out some crazy fuel.

 

True supermentals do put down alot of smoke.. but I forgot to mention that the truck A (BDIII) smoked more too than truck B????

 

Yes... I was thinking the same thing when they dynoed, nice Q. Lynn

 

Erics pressure stays around 22 unless he stands on it. Far as I no he never has hard starts.? (Truck A) Ive heard that over 20 psi you can have hard starting and damage to your vp

 

No, the more FP you have the faster you can fill an open cavity in the pump before it closes to send the fuel out to the lines.

 

I have heard that you don't want more than 18psi inlet pressure to the VP. I know where folks were dabbling with different pusher or other pump setups, those that ran the higher pressure (near 20psi) often got hard starting.

I think the ideal system would maintain 16-17 psi under all circumstances, but lower to allow the engine to start.

There is a REASON that the stock LP will only put out about 5psi until the engine starts.

I looked hard at the Aeromotive A1000 pump, and then the PE4200. Both seem to be pretty good pumps.

As for the HP differences, I personally think that the FP differences played almost NO role in the HP differences. The bottom line is that BOTH trucks were overfueled. But because the SMs put out more fuel than the BD3s, the SM truck was MORE overfueled than the BD truck.

As a result, the SM truck would put out less power because the excess fuel saps the heat from combustion.
This is a case where more fuel does NOT mean more power.

Case in point: I have run my truck (EZ and DD2s) against a similar ETH that had a Comp and 3s. Guess what? SOP power was almost identical, but his smoked a lot more. We both had stock turbos and exhaust.

There is a certain point where more fuel means LESS power for a given amount of air. The presence of smoke does NOT necessarily mean that a truck with elss fuel would have more power. But it DOES mean that the truck could add air and make more power with that given amount of fuel.

Justin