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-   -   How much boost are you getting with 3.4" pulley?? (https://www.gmforum.com/forced-induction-105/how-much-boost-you-getting-3-4-pulley-188703/)

2000SilverBullet 05-11-2003 01:12 AM

How much boost are you getting with 3.4" pulley??
 
With the 3.4" pulley I am barely getting 10 psi.
9 psi most of the time.
Is anyone running with the 3.25"?
How much boost are you getting with it?

willwren 05-11-2003 11:41 AM

Are you still running with stock exhaust? That can cost you indicated boost. I checked your sig, but I don't know if you got ahead of your list or not.

2000SilverBullet 05-11-2003 03:38 PM

Yes I still have the stock exhaust.
But I thought that opening up the exhaust will actually drop your boost not increase it???

Rotgut 05-11-2003 11:09 PM

Your boost isn't really gonna drop unless you get ported manifolds or headers, a cat-back really isn't gonna do too much. It's been such a long time since I had a 3.4" pulley that I don't remember what you should be pushing. I went from 13 to 11 psi when I put headers on my old '99 GTP with a 3.25".

I'm probably gonna put a 3.25" on the new Bonnie in the next month or so, I'll let you know what happens.

GTX COWBOY 05-15-2003 09:41 AM

my 3.4 gives me almost 11 on otherwise stock exhaust, headers should drop that about 2 psi.

willwren 05-15-2003 01:57 PM

You're still getting the air volume in a situation like GTX is talking about, but it's like blowing air into a ballon with a small hole in the other end. You're going to read less pressure, but the volume is still there, and you still benefit from the swap.

turtle_sse 05-16-2003 01:20 AM

:bouncingsmiles: ummmmmmmmmmmmmm 11 psi?? heehee... :headbang2:

willwren 05-16-2003 04:53 AM

Quit your laughing old fart. Most of us can't AFFORD a Garrett T45 turbo. I do a wee bit better at 12psi.....but at least I don't have to wait for mine to SPOOL UP, and it makes an awesome whiny noise.

:banana:

I love that fruit. Reminds me of Drifter.

2000SilverBullet 05-18-2003 11:01 AM

Will,
You recently installed a 2.2" pulley. I know you have the series 1 engine and the pulley sizes are different than the series 2 like mine but I think you stepped down in size more than one notch. (pulley boys lists Series 1 sizes of 3.0" all the way down to 2.2")
What was the original size of your pulley?
What made you decide to go with that size first?

I'm trying to decide on how small a pulley size I can go to. Pulley boys list two sizes for the Series 2, 3.25" and 3.0". They don't even list a 3.4".
My engine runs cool and I use an octane booster along with 94 octane fuel so I'm not sure I should be concerned about knock retard.
You have the Jet chip which must help.
Do you think I might need a custom computer burn before I should attempt a switch to 3.25"?

willwren 05-18-2003 01:40 PM


Originally Posted by 2000SilverBullet
Will,
You recently installed a 2.2" pulley. I know you have the series 1 engine and the pulley sizes are different than the series 2 like mine but I think you stepped down in size more than one notch. (pulley boys lists Series 1 sizes of 3.0" all the way down to 2.2")
What was the original size of your pulley?
What made you decide to go with that size first?

I'm trying to decide on how small a pulley size I can go to. Pulley boys list two sizes for the Series 2, 3.25" and 3.0". They don't even list a 3.4".
My engine runs cool and I use an octane booster along with 94 octane fuel so I'm not sure I should be concerned about knock retard.
You have the Jet chip which must help.
Do you think I might need a custom computer burn before I should attempt a switch to 3.25"?

Series 1 will fool you. The 92/93 is 2.5" stock, and the 94/95 is 2.8" stock. The neat thing about this is that the 94/95 uses the stock 92/93 pulley diameter for performance. The M62's are slightly different, as is the TB diameter. Hence the difference. Some pulley manufactureres used to offer a 2.0" for the early years, but that's really self-defeating as far as heat is concerned, unless you run an intercooler. But nobody offers a series 1 intercooler. I'm really happy with the 2.2. If you figure out the ratio for the 2.5 to 2.2 change, I'm really happy with it. Not sure on what it did to mileage, cuz I can't keep my damn foot out of it long enough to see!

Pulley Boys used to offer a 3.6 and a 3.4. Not sure what happened. It may be based on what stock he has on hand. Email Brian and ask what's up! 3.8 is stock for a Series 2 M90.

As far as custom burns are concerned, you still have a Jet option. I'd look at that before a custom burn. If you do burn, wait until you've done EVERYTHING you're gonna do. Get it all if you're gonna drop the cash on it.


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