Engine/Transmission (1998.5 - 2002) Need the skinny on my pump and mach 6's

[DHayden]

Ok I know the mach 4. 5's suck up all the fuel the VP44 provides. I take it this means if I had mach 4. 5's that my comp would provide no extra fueling even with the wire tapped? Since I am planning to get a HPVP44 down the road, if I decided to get the 6's now how would they be?

They would provide no more fuel than the 4. 5's (because of the pump) but they have different spray patterns no? Will they be more smokey or get allot less mileage than the 4. 5's even though they are only putting out the fuel of a 4. 5? Shouldnt the temps be the same as the 4. 5's would be? My comp would be rendered basically useless except for timeing. How effective willthe 6's and the comp become with an HPVP 44? Will the HPVP 44 provide all the fuel a comp or similar fueling box and mach 6's can use?

Hope this is understandable, thanks for the help.

 

[rubberneck]

I can answer this as that is my exact set up (sig old, now have 4. 5s instead of 4s) I believe when they say 4. 5 takes all the fuel the ETH pump can give, they are referring to when the comp (or other pump tap fuel box) is in use. I can tell you that when you turn the comp on there is a lot more power than when off. So to answer your question, I would assume 6's would give you more power over 4. 5s, even with your stock pump, when the boxes are off. However, with the boxes on, you might not see much if any HP increase. I dont know anything about the HR vp44s, so can not comment on how much more injector they will allow you to run. When my vp44 finally dies, it will be replace with a nice big honkin inline pump. screw the electronics

 

[Bob Wagner]

The HRVP can use a MAch 6 or 7. If he has serious plans to go to the HRVP then a set of 6's or 7's would be the ticket.



If he is going to stay with the stock HO pump, he can go with 6's but he wont get to 600 HP. 550 is more likely. The stock HO pump is volume limited and cant inject enough fuel to make the 600 or more the SO pump can. The HRVP fixes this problem by increasing the volume of fuel. The stock HO pump should stop around a Mach 4, because the dyno peak HP will be not much better with anything larger. Power under the peak graph is better with the 5 and 6 though. Sled pulling is better and drag racing is better with a larger than Mach 4 though, even with the HO pump, but they cant get the "advertised HP" from the 5, 6 or 7. I try and discourage people from buying them if they are after a large "peak" number and are using a HO pump.



I would go with the 6's or 7's and get the HRVP myself. YOu cant hurt anything by using a 6 or 7 with the stock HO pump though.

 

[DHayden]

Thanks for the replies fella's. Will the smoke and egt's of the 6's with stock pump be about the same as the 4. 5's or worse?

 

[Hohn]

I'd think smoke and EGT will be worse-- but maybe not by much. Because of the volume limitation, prressure falls off at the end of the injection event, and this hurts the burn.

I'd wait until you got a HRVP before you went bigger than 5s. Get the HRVP and go big.