[DaveN]

When I was in Paso we discovered I had no Whoosh. I think it was BanditSC who drove my car and wondered where the whoosh went. We found I had not yet set my regulator to 53 PSI; we did that and I had whoosh! I have noticed lately that when I get close to redline the whoosh and venturi squeal are diminished. I checked my fuel pressure and it was at 50, down from 53. I reset it back to 53 and it seems to be a little better now but not like it was. I am wondering if the small dent in my exhaust pipe, a present from the Paso mountain pass, would restrict the gasses enough to cause this or maybe it's something else like the fuel pump not providing full volume?

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[Inkedupfatboy]

Are you getting older? Maybe you need a bottle of Ageless Whoosh!

Sorry couldn't resist...lol

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[flash]

the exhaust should not affect the intake sound. that screech is related to the venturi.



check your air filter. if it's clogged, you may not be getting enough flow.



as for the fuel pressure, that's bloody weird. it shouldn't change. did you put loctitie on the threads of the regulator, and remember to tighten the locknut, using the allen to hold the screw still as you did it?



if so, then i would be looking at the fuel filter and/or check valve first.

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[tamathumper]

My fuel pressure dropped to 50 over the course of a couple thousand miles too, and was re-set when I fixed a small vacuum leak around the threads on the fuel pressure regulator. I used a slightly larger drop of Loctite the second time, but I didn't want too much on there for fear of it getting into the FPR.



It had no impact on the "shriek" at 6500 RPMs, but when I tightened up the belt on the supercharger this time around, the shriek is gone, making me wonder if it was belt squeal all along. <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />

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[Lear35A]

The venturi sound and the belt squeal sound are different, but if you haven't heard them both, it would be easy not to know which is which. With the tighter belt you now have to be alert to the sound of a failed idler pulley on the SC. <img src="/forum/images/smilies/968/glare.gif" class="smilie" alt="" />

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[tamathumper]

I tried again this morning on the way to work, and I do still have that little "squeal" of the air flow. The belt slipping is a pretty similar sound and easy to mistake as the same thing. With only one unit to work and play with, each of us will have to learn our way into it.

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[flash]

belt slip and venturi squeal are very different. how do i know? because i have multiple venturis (i had different sizes made up to determine which was best), and can tell you that each one makes a different sound.



it's pretty darned hard to get belt slip. you really have to have that thing loose, and it should be making a racket all over the place before it does. belt slip can be misdiagnosed, and in reality is boost escaping elsewhere (cam overlap, leaking valve guides, etc)

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[DaveN]

My belt tension seems to be bang on. Didn't have Loctite at Paso but we did tighten the lock nut itself - wasn't loose when I went to readjust it. Air filter is pristine. Maybe I can rig up a temporary boost gauge when the car comes off the road and see if I am getting the Full Monty?

I do have a 20 year old fuel pump as well, I know because every once in a while I can hear it chattering back there. Maybe it might be time to look at that as well.

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[Lear35A]

[quote name='DaveN' timestamp='1382037078' post='150868']

My belt tension seems to be bang on.

[/quote]

Ah, the holy grail. How did you determine it to be "bang on"? Numerous inquiring minds want to know.

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[gbarrier]

I want a "Bang on" gauge. Does the meter also have a place on the scale for "bang off" and "almost banging"?

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[tamathumper]

Well I'll be darned... There IS a gauge for "bang on".

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[Lear35A]

Only available in Canada I'll bet.

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[Rap]

Looks like a Canadian cholesterol medical device. Non taxed of course!

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[Langley968]

[quote name='Lear35A' timestamp='1382056604' post='150884']

Only available in Canada I'll bet.

[/quote]



Given what the US just went through... it will be a LONG time before there is an American version of the "bang on" tool! <img src="/forum/images/smilies/968/icon_lol1.gif" class="smilie" alt="" />

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[DaveN]

All right, someone has been into the "too funny" sauce again - Tama.

I say my belt feels like that because when we rebuilt the engine I ordered the Corvette belt as per Bob's part number. It was really tight to get on unlike the first time in LA at his house. After running for about 1500 km's it has stretched enough to feel like the original install negating the need to retention. Spitting out about the same amount of dust as well which isn't much.

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[Rap]

Good lord Dave, simmer down now, we had the gov't close down not yuz guys.

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[tamathumper]

Sorry, too much time on my hands, I guess. <img src="/forum/images/smilies/968/wink.png" class="smilie" alt="" />



Is there a specific deflection, tension, or other measurement you could communicate to the rest of the crew?

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[flash]

lol - all this broo-ha-ha over belt tension. i think you guys are over-thinking this. the window is pretty wide. it's just not that critical, until you get it too tight.



maybe i should have made the belt guard so that it stood farther away from the belt. that way you could leave it pretty loose and still not smack the thing.



if your alternator isn't slipping, it's not too loose. that will slip long before the sc, and you'll hear it down at lower rpms when you nail it, just like you would on a normally aspirated car.



boost loss does NOT necessarily mean belt slip. boost can find its way out any leaking item, and can even hold all the way up to the point where it leaks, depending on which thing is leaking. valve guides and seals are a big one. the oil coating will hold a seal up to a point. then it will blow out and leak boost. the tiniest of gap or misfit of a hose can do it too. i had a temp wire slipped under a hose and into the intake. i had the clamp REALLY tight. i was still losing over a half pound of boost. same goes if you have the clamp riding on the ridges or bumps on the fittings. they need to be fully past those.



i have yet to have a belt slip and cause boost loss. i'm not even sure i can force it to happen. there is just too much wrap on a fairly large pulley, with plenty of grooves for this boost level, with short distances from there to the next pulley. we have more tension on this belt than any self tensioning device would provide, and the belt doesn't slip with those on any other kit that is similarly set up.

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[DaveN]

Yeah I'm not worried about the belt, I doubt it is slipping. Correct me if I'm wrong (Flash would never do that <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" /> but regardless of leaks etc. if the belt is driving the SC properly you will always get the same, repeatable venturi scream at a given RPM? Assuming of course that the air is passing through the intake system at the nominal flow.

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[flash]

yup

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