SVO Eaton blower setup randomly making more boost than it should sometimes? WTF

Speeds8erM-1 · Jul 11, 2009

Im having a weird issue. Car usually makes 5-6 psi, well sometimes it will creep up top 7-8 even 9 psi. It seems to only do this after driving around for awhile, and when shifting really hard. The car almost kind of surges slightly on the shift, then the boost gauge starts creeping up. If I just roll into it in third and start going, it doesnt get that high. It's an electric digital Nordskog gauge.

I wonder if it's something with the bypass valve? The bypass rod is adjustable.

You can see where the boost gauge is plumbed on top of the intake near the EGR.

DropTopPony · Jul 11, 2009

It has to be belt slip, these blowers build boost fast and at low rpms. Did you ever get your tensioner checked? The stock is aluminum and prone to bending. A steel replacement is sold by Ford because of this.

Back when these blowers were popular guys would notch grooves in the pulley to assist with the belt slip on the 9 and 12 psi pulleys but never seen it on a stock pulley.

Are you sure your boost gauge is accurate?

Speeds8erM-1 · Jul 11, 2009

I dont see how belt slip would cause a boost increase. Not sure how accurate the gauge is, but it only makes more boost when it surges on a hard shift.

blown98gt · Jul 12, 2009

i'd say belt slippage also, the eatons are notorious for doing this.. any blower will do it really but yeah i'd say belt slippage is the reason of boost jumping.

when did you last replace your belt?

justinschmidt1 · Jul 12, 2009

Speeds8erM-1 said:
I dont see how belt slip would cause a boost increase. Not sure how accurate the gauge is, but it only makes more boost when it surges on a hard shift.

Seriously man?

Were saying the blower is pullied for like 9 psi...but since your getting belt slip most of the time your only seeing 5-6...so when your seeing 7-8-9 the belt is not slipping....get it?

blown98gt · Jul 12, 2009

key words here..

SURGES ON HARD SHIFTS

that right there tells you it's belt slipping issue.. so option A. convert to 8 rib pulleys and see approx 1-3 more lbs of boost or B. buy a Gates belt and keep buying new ones when you get belt slippage.. IMHO i'd switch to 8 rib after i did that i'm my D1sc i saw 0 belt slippage and gained a few extra lbs of boost

Speeds8erM-1 · Jul 12, 2009

It's NOT PULLIED FOR 9 PSI! It has the stock pulley on it, 3.5", it's a 6 psi kit for a stock motor non pi car, my heads etc flow more than stock, it's 100 degrees outside, 9 psi is not an option. The gauge doesnt flutter like slippage, not even at high rpms. The previous owner said he never saw more than 5, 6 tops. When he had it tuned 7 years ago, it made like 5. It's not pullied for 9 psi, hence the issue here. The only guys seeing 9 psi out of these blower setups, have different pulleys, which have to be made by ASP or Pulley Boys, this car still has the stocker.

justinschmidt1 · Jul 13, 2009

Just becuase its pullied for X psi doesnt mean it always makes x psi.

My car is pullied for like 17 psi, it makes 11

Speeds8erM-1 · Jul 14, 2009

You probably have a good flowing motor, or a big ass intercooler. The kit was DESIGNED FOR A STOCK NPI car, mine flows MORE, so 9 psi is a problem, the car isnt pullied for 9 psi and shouldnt make 9 psi on this combo. If it were supposed to make 9 psi, Im sure the previous owner of the car would have noticed in the last 7 years it's been blown. It made 5-6 psi when it was dynoed both times back in 02. I even took the cats off, because I figured maybe they were plugging up, not the issue, apparently. The only guys that see that kind of boost on these blowers have custom pulleys from ASP or Pulley Boys. It's also 100 degrees outside, not winter time.

If anything, I wouldnt see an INCREASE of boost on the shift if it were belt slip, I would see it start to act up in the higher rpms. The point is, I NEVER SEE that boost unless I shift the car hard, like the bypass valve isnt doing it's job with getting rid of extra air or something.

justinschmidt1 · Jul 14, 2009

Speeds8erM-1 said:
You probably have a good flowing motor, or a big ass intercooler. The kit was DESIGNED FOR A STOCK NPI car, mine flows MORE, so 9 psi is a problem, the car isnt pullied for 9 psi and shouldnt make 9 psi on this combo. If it were supposed to make 9 psi, Im sure the previous owner of the car would have noticed in the last 7 years it's been blown. It made 5-6 psi when it was dynoed both times back in 02. I even took the cats off, because I figured maybe they were plugging up, not the issue, apparently. The only guys that see that kind of boost on these blowers have custom pulleys from ASP or Pulley Boys. It's also 100 degrees outside, not winter time.

If anything, I wouldnt see an INCREASE of boost on the shift if it were belt slip, I would see it start to act up in the higher rpms. The point is, I NEVER SEE that boost unless I shift the car hard, like the bypass valve isnt doing it's job with getting rid of extra air or something.

Your bypass wont let any air escape at WOT, bypass is designed to let air out at part throttles, its not supposed to regulate boost like your saying it should.

I really have no idea why it would read higher...the only thing that can raise boost is the pulley size and restriction...maybe your boost gauge is just off.

What kind of gauge? have you tried a differant gauge?

Speeds8erM-1 · Jul 14, 2009

I lift a hair on the shift, and it all happens hard and fast. If I shift kind of slow it doesnt do the issue. I would think the gauge is on crack, if I didnt feel the surge when it does it. Im going to replace a suspicious looking vac line tomorrow and see if that does anything. A guy on corral said years ago somebody had issues like this, and it was intake gaskets. Weird.

Speeds8erM-1 · Jul 16, 2009

Messed with the bypass today, it DID make a difference. Now finding the fine line between where it's too much & not enough is going to be fun.

justinschmidt1 · Jul 18, 2009

Speeds8erM-1 said:
Messed with the bypass today, it DID make a difference. Now finding the fine line between where it's too much & not enough is going to be fun.

Im not familiar with your setup but if it made a differance then there is something wrong with a vac. line possibly

The bypass should be fully closed at WOT, if its not then something is not right,

Speeds8erM-1 · Jul 18, 2009

It was closed at wot, but on the shift, it wasnt opening and closing fast enough when I was lifting a hair, is what I believe the issue is.

blown98gt · Jul 18, 2009

if it's not opening and closing fast enough could be the bypass valve or could be the vac line. I'd pull off the bypass valve and clean it and make sure that nothing is blocking the vac line then i'd replace the vac line going to the bypass

Speeds8erM-1 · Jul 19, 2009

Vac line actually looks really good. I dunno, without the stud that keeps tension on the bypass, it's doing the WOT boost climb on fast shifts again. I have an allen headed screw to put in, to be more exact with the tension on it, to be able to make small changes. Also today, it started trying to make more boost, I lifted and got back on it, it dropped boost to where it's supposed to be. Weird.