nmerrill

For those of you with experience what is the max boost you can run on a stock 5.0? Right now i am running the 12# pulley, but my car is getting tuned on tues, and i want to get all the power out of it that i can. Mods are TW heads, TF stage 1 cam, track heat intake, s-trim, 255 LPH pump, 42# injectors, and kirban regulator. I have an 18# pulley, but i dont know if my fuel system will support it, or if my head gaskets will hold. FYI the head gaskets are stock type fel-pro's.

FullAuto

Chances are you'll never see an actual 18psi with that pulley. You're going to get into the area where belt slip will start to take away boost. With 12psi, you should be in the 475-500rwhp range. I think you going to run out of fuel pump pretty soon. The motor will probably take 15-16psi though if you can make it before 6000rpm.

nmerrill

Cool, it is a cog setup (dont ask me why, it was on it when i bought it). Will cogs slip? either way, if i would really be around ~475 ill just stay with 12#. I really thought it would be low 400's with only 12#'s.Would a t-rex pump help out, or should i start thinking more serious?

FullAuto

Cogs won't slip. They are hard on stuff on the street though. They tend to break balancers and crank keyways on street driven cars. With what you have, you're probably just about maxed out that single 255lph. People have made 500rwhp with one and have done it for a long time, but most people do run an inline with it at that level. Don't buy the t-rex. It's a 190lph pump. Buy a Walbro 255lph inline if you decide you want the extra peace of mind.

Do you just have a 12psi pulley on it, or do you have a boost guage and actually see 12psi? With 12psi through TW heads and Track Heat intake, I would expect to see in the neighborhood of 475rwhp on a Dynojet. If it's a Mustang Dyno, all bets are off. There are several small factors too, but I'd be disappointed with low 400rwhp.

Does the S-trim have an upgraded bypass valve? If it's a stock bypass valve, don't even try the smaller pulley. You'll need at least a race bypass if not a Mondo to run 18psi.

samseed101

The inline pump will help keep the pressure up so it may not be a bad idea. Not 100% necessary but i think they are helpful. 12 PSI with an H/C/I is getting up there though. Going to be pushing the block itself near it's limits if you try to go higher. I think 18 will be certain death, especially with your current fuel setup.

1991LX5.0

i would def stick to the 12 lb pulley. I also think you should be in the 450-475hp range. Im putting down 450 at 8lbs but i have slightly bigger heads and a better cam, same intake

nmerrill

I have a boost gauge, but the car is untuned, so i really havent hit any serious boost(just being nervous). I havent even taken the car over 3k rpm. I will be driving to murillo's on Tuesday to get the tune done, and he uses a mustang dyno. I have heard they raed less than a dynojet, and then i have heared some people say they read more for boosted cars, and on and on..... I guess we'll see on Tues! As far as the bypass valve goes, nothing was mentioned when i bought it so i assume its stock. I will just stick with the 12# pulley, and see where that gets me, thanks man!

FullAuto

The Mustang Dyno will definately read less. I went to Murillo's a few years back (Jan. 2005 I think) and he had a Dynojet. I heard he had moved since then and changed to a Mustang Dyno though. He's a good guy. I got him to autograph my chart too.

AdderMk2

381.4 psi

LCBlackDep183

I would stick with that #12 and get a solid tune, you should be okay with the intake FP but the inline couldent hurt by any means, that just means they're not going to have to work as hard, making it less likely they will fail.

Your going to be pushing the limits of alot of your stock parts with that setup so I wouldent press it much more.