Bman2000

ok so pretty simple i want 14-16 psi out of my vortech si trim. But i only have factory heads and cams. Can i do it? and what do i need? im guessing i need to go 8 rib, and probably an overdrive crank? and what size pullie? can people give me their combo and power levels? im thinking about forging motor and i figure my fuel system and everything is already set up to handle my si trim maxed out. So can i get there with without heads and cams, also im guessing i would have to upgrade to a 4 core intercooler? please help me get this figured out.

lizzyfan

17 psi here with built mota, H/C running a T trim (upgrade from an V-2 SQ, but really the same as an Si trim) 6 rib with 2.87 pulley. 96-99 tensionsers are 3 bolt as apposed to your 2 bolt so you'll prolly have to do an 8 rib setup.

Bman2000

yea but you have heads and cams? what do you think i can achieve without heads and cams? at this point i think i cracked a piston or more than likly screwed up a wrist pin since it sounds like a rod knock but im missing lots of power. But anyway im just trying to get by with a budget build if i can, so i was considering upgraded rods and pistons if i kept the block and heads and crank from being damaged and maybe new valve springs. But other than that i have 60# injectors and twin pumps so my car should be able to handle it. i figure the crank should be good until 500-600 to the ground, from what ive heard i just can spin it to 7k, which wont matter since im running factory cams id be checking out around 6k anyway. Also what do you mean about the tensioners? i didnt know they were different? i think i have belt slip now with a 3.33 pullie and a new tensioner im impressed you have that much psi with a 6 rib combo.

97stanger

When I used to run an SI I was seeing 15-16psi. You will need at a minimum a 10% overdrive crank pulley, 8 rib conversion, probably 2.95 blower pulley. Better flowing heads will lose psi, not gain. Same with an intercooler. Just keep in mind theoretically, the better breathing setup you have the less boost you will see, as it is just a restriction measurement. I dont know if I'd set a psi goal, but more power/et goal.

lizzyfan

96-99 where/are better as they are three bolt and gave more belt wrap at the crank. I even upgraded the stock tensioner with a a Ford steel (no longer avail) tensioner. Zero belt slip and I've been running this pulley almost 3 1/2 years

lizzyfan

Thought about that but did not want to go over 17 psi on pump gas

97stanger

methanol injection!!!!!

Bman2000

I keep forgetting about boost being a measure of resistance. I guess I just have been having issues with boost though that's why I worry. I mean right now I'm running a 3.33 pullie a home made power pipe and an intercooler. But at 6k I only saw 7.75 psi now on the measure of restriction board it just means my car is flowing well since I would imagine that combo making closer to 10 but the bottom line was I still only made 360rwhp granted that's through a t56 but I figure that cost me around 20 hp over a 5 speed, but I figured my set up would have netted me closer to 400 or 380 with a 6 speed, because that's a fairly common number I'm seeing from other people with similar stuff, but they make around 10 psi and I'm not. Anyway I was planning on 8 rib and a 10% or anyway since I figured that'd be easier on the belt, but good to know pullie size. Power wise I'd love to see 500rwhp but with my Dyno luck lately I don't know if 14-16 psi will be enough for that?

TonyG

An 8 rib set-up is nice, but it's not imperative. I got to 21 psi with a 6 rib set-up. Sure the belt slipped a little, but that was fine.

When I had my stock shortblock, I made 513 rwhp with blower cams, stock heads and stock intake. Even the throttle body was stock. Blower pulley was 2.8", crank pulley and tensionor (3-bolt) were stock. I saw 15 psi at 6400 rpms, and ran low-11's at 126. I eventually swapped to a new setup with a forged shortblock, but the stocker never blew...and I raced it hard for two seasons.

uberstang1

Fred i wouldnt be concerned there are a ton of car with 20-23psi and pumpgas nowadays with safe tunes