Engine/Transmission (1998.5 - 2002) Higher HP guys - I have got a question :D

[turbo lcc]

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

 

[Piston Slapper]

You don't want above 20 psi at the inlet to the VP44 on start up due to it can create a hard start condition. Anything greater than 8 at Wide Open Throttle is .

 

[turbo lcc]

so with only 8psi (and the right goodies) I can acheive 500 rwhp?? one of the reason I ask it I was watching 2 almost identical trucks dyno. . -



- stock turbo

- Edge comp (no drag on either)

- 4in ex

- 2002

- one with BDIII(100hp)

- the other with Super mentals (120hp)

- 6 speeds

- AFE mega cannon



- other than injectors the only difference was the fuel system (psi @ WOT)



Any ideas as to why the one with BDIII would put down ~410rwhp and the truck with supermental only put down ~370rwhp.

 

[KLockliear]

Doesn't seem to matter as long as it's over 6psi. Our old white truck had our cam and a 12v lift pump. Made over 50psi at the inlet to the VP44.

 

[Piston Slapper]

The greater the pressure the better within reason. Below 8psi you can potentially starve your VP44 for fuel. Flipped side, too great of a pressure (greater than 20 psi) on start up can cause a hard start.



Keep in the double digits at WOT and you are doing great! Usually over 500 hp requires a pusher pump of some sort.

 

[turbo lcc]

I just seem really odd that there would be that much difference in dyno results concidering the setups. The truck with the lower HP was running ~9-12psi the truck with the higher HP was ~18-22psi.



Just so I am clear what you guys are saying is :



Assuming both pressures are solid this could not have been the ~40hp difference in the trucks?

 

[turbo lcc]

One thing I did leave out was the Higher HP truck ran -8 lines and the lower ran -6 lines...



Not sure if that would make a difference either.



Thanks

Lynn

 

[01_HO]

Hmm.....

 

[JR2]

Any ideas as to why the one with BDIII would put down ~410rwhp and the truck with supermental only put down ~370rwhp.

With a stock turbo the truck with the supermentals was starving for air, then again a stock turbo with BD3's would be in almost the same boat.



JR2

 

[01_HO]

What if the truck with the IIIs put alot more smog in the air?

 

[jrandol]

Mine is about 10 psi or so, power levels are in my sig. I ran a stock HX35 12cm for some time with Stage 3 injectors, have to say I would not recommend doing that.

 

[FAHLGUY]

I run 18-19 psi @ idle, and normaly cruising it is at 17-18. I can drag it down to 14psi @wot. I am monitoring the pressure right before the VP44.



From my experience you can go over 20lbs, and not have short term problems. In the long run hard starts may occur, and I have also seen the front seal blown out of the VP44.





Bill

 

[2ndgen2500]

lol BULLY DOGS are the smog kings!!! but the SM and BDs should both be starving for air, that is a strange dyno result in my opinion.

 

[Rman]

I don't think a stock 35 can provide sufficient air to support the fueling of supermentals... perhaps this is why the truck ran 40 hp less. It was running too rich and lacked the flow to build higher boost, i bet the egt's were higher as well.

 

[c-hawk]

Maybe most of the variation is for no other reason than not all trucks run the same. I dynoed 415hp on an hy, stock fuel system that was straining, standard comp and dd2's. Some trucks just seem to make more power than others.



JMO,

chris

 

[TractorNut]

Sounds more like the truck with the SM, was not getting the Full HP out of his box. . like a bad connection at the pump wire... As someone stated above... they made over 400 with II's and a comp... .

Bryan

 

[78repowerwagon]

Could the lower power truck have a vp headed south?

 

[DavidTD]

I have seen consistant 425hp with a stock HX35, good fuel filter, good air filter, etc. using Bully Dog IV's (120hp) and an Edge Comp. This truck had a SunCoast Triple Lock transmission.



Not enough transmission, dirty air filter, dirty fuel filter, different truck configurations (3500vs2500, or 4x4 vs 2wd) all have impacts on the numbers. Fan clutch operation and so on all impact numbers.