jkel1124

iTrader: (3)

/\ So that is what's going on. It hits 12psi pretty quick and then fades away right around 4800rpm down to about 8psi at red-line. It has an ECS tensioner w/ only 6-rib belt (2.8 jack, 8" crank, 1:1 rears). Dyno'd it recently on a Mustang to check AITs in this horrible 100+ weather and it maxed at only 439hp at 4800 and 549tq at 3200 with max AITs at 180. Belt slip or is the maggie out of juice and heat killing it?

Onefast V

iTrader: (3)

What was the max boost on the dyno? What belt length are you running? Are you running a crank overdrive pulley? maggies do run out of breath quickly when you spin it faster than stock

jkel1124

iTrader: (3)

He didn't monitor the boost on the dyno run but I assume it did the same as above...it does that in every gear. The crank is o/d with 1:1 rears and I'm running a 102HD Green Stripe.

jkel1124

iTrader: (3)

Here's a run:

Onefast V

iTrader: (3)

Couple options. You can run 101.5" blue gates racing belt and it should grab better. If that doesn't work it look into 8rib setups. Also maybe considera bigger supercharger idler pulley to help the belt wrap around the drive pulley more

2007V

iTrader: (2)

I don't hear belt slip. I have the same pullies and tensioner except 2.7 front and keep 12 psi the whole way, but mine is definitely slipping at 5800 rpm or so. I don't see a drop in boost when I hear my belt slipping.

Is there heads/cam on it? I say either the blower is maxed out or the bypass is opening. Zip tie the bypass closed and see what happens.

It could also be the intake choking it off...

Edit: it's a smooth transition losing boost, it's heat.

Edit 2: my iat's are 140 maxed for reference. 180 is going to lose boost. I bet on a cold day it hauls!

There is shake at the end, is it knocking or being torque management limited? That may contribute as well.

jkel1124

iTrader: (3)

I had that belt and for some reason it ripped apart in under 500 miles. I've had this one on for 1500 with no probs. Also I already have an 85mm idler.

Stock heads with mild port and small cam GT2-3. Yes in the winter it is an entirely different animal. My car hates TX summer as much as I do. I'll try the zip tie and see what happens. Also I am still running stock tb if that might be a prob...not enough air getting in?? The intake is a Volant w/ custom added tubing and use 50/50 meth/water. Oh and the shake at the end is from bouncing off rev limiter.

gaskill

When mine was pullied for 6/7psi boost, had 20* timing with 120 IAT. After pulling for 10/11psi, my IAT rose above 130 & timing was cut to 14*. I also run 50/50 meth. My guess is your tune is also cutting timing, losing hp.

jkel1124

iTrader: (3)

So due to my AITs I'm obviously loosing timing and hp, but will that cause the boost to fade?

GFallen

Sorry to thread jack but gaskill what did you do to get 580whp out of a 112, I assume? Very impressive...

2007V

iTrader: (2)

My guess is heat. Can you put a bigger IC pump on or do something else? Are you using an omega mod iat sensor? That would be a cheap start to see what the temps really get to.

It's an 04/05 TB? Positive displacement blowers are really sensitive to any inlet restriction. You would see a nice gain with a larger one.

2007V

iTrader: (2)

Oh, is the crank pulley pinned? Maybe a pulley on shaft is slipping.

jkel1124

iTrader: (3)

I'll try omega mod and also change to a 90mm tb and see where we are. And the crank pulley is pinned. Thanks for all the input!

gaskill

Boost Psi is measure of air restriction. The better the heads & cam are at flowing air, the more boost will go down. The motor is showing good power with 549tq. Mine starts @ 10.5psi & is down to 8psi @ 6000rpm. I am going to add Torco to my fuel to raise octane & see if it helps get some timing & HP back. You might try this, before you spend $$$ on parts. Good Luck