[Charlie540i]

I'm looking for people who have used a Whipple in a cammed, ported heads, 2.0" long tubes and full exhaust with a 9.17" overdrive lower to check upper pulley combo and boost level.

Lets say lower 9.17" or larger with a 3.50", 3.25" or 3.62", how much boost are you getting from those pulley combinations with a Whipple on either a LT1 or LT4?

[Hilltopper]

I have a 9.17" lower and 3.5" Upper. 12 lbs of boost with LME 10.5:1 setup. Headers are 1 7/8".

[Joe's_cool_1le]

Guessing the 8.4 and 9.1 are fairly new. When I did mine they only offered the 8 which I installed. Went from an upper 3.125 and 7.0 to a 3.500 and 8.0 combo. That change kept my numbers pretty close (whipple speed from 14560 to 14857 @ 6500RPM's). AEM boost gauge shows low 13's with my setup. What drove me to this was belt slip though which it resolved.

I believe for about every 550 increased in blower speed equals about 1 PSI. So if I were to have a 9.1 and a 3.500 I would expect to see about 3.75 more PSI (17PSI)

[Joe's_cool_1le]

Originally Posted by Hilltopper

I have a 9.17" lower and 3.5" Upper. 12 lbs of boost with LME 10.5:1 setup. Headers are 1 7/8".

Interesting. I must be missing other factors because I'm making more boost with a smaller lower with a pretty close setup.

Ahh... I'm still on a stock TB. And you look to be moving air much better.

[Chris V]

I don't know what the boost was, but when Jannetty was going through my car they tried an 8" lower to go with my 3.625 upper (Version 2 whipple) and it basically ran out of fuel - 650 wtq before it got into knock retard and they abandoned the run.

I think the version of the Whipple has something to do with you having more boost on less pulley.

On 7" lower and 3.625 upper I'm at 9.8 max boost with an average of 6.8 across the dyno pull.

[Hilltopper]

Originally Posted by Joe's_cool_1le

Interesting. I must be missing other factors because I'm making more boost with a smaller lower with a pretty close setup.

Ahh... I'm still on a stock TB. And you look to be moving air much better.

Actually......I stand corrected. 9.17 lower and 3.75 upper. I forgot we changed uppers from 3.25 to 3.75 when we swapped lowers. The 3.25 with 9.17 made too much boost for my setup. Ended up with around 12 lbs of boost with the 3.75.

[Charlie540i]

Thanks for the replies. I'm working on a 2018 ZL1-1LE and using a 9.17" lower and a 3.25". I haven't got it on the dyno yet to do more controlled testing, but so far the MAP readings are really high when I go WOT juts in 2nd and part of 3rd gear.

Just comparing with you guys, as per Whipple I should have 15psi and I'm seeing a lot more than that. Well, at least according to MAP.

[Hilltopper]

Originally Posted by Charlie540i

Thanks for the replies. I'm working on a 2018 ZL1-1LE and using a 9.17" lower and a 3.25". I haven't got it on the dyno yet to do more controlled testing, but so far the MAP readings are really high when I go WOT juts in 2nd and part of 3rd gear.

Just comparing with you guys, as per Whipple I should have 15psi and I'm seeing a lot more than that. Well, at least according to MAP.

That's exactly the same problem we had with mine. The 3.25" upper on the 9.17 lower made WAY more boost than it was supposed to. If I remember correctly, the run was aborted in the 5,500 rpm range with boost climbing way past where they wanted to be (17+ if I remember correctly). They changed the pulley to the 3.75 and settled on the 12ish psi. Much better belt wrap, as well.

[GT-ER]

I have a 9.10 lower and 3.75 upper and make about 15.5psi but I'm on stock cam.

[Charlie540i]

Talked to Whipple, there was a communications problem... to get 15psi with a 3.25" is when using a stock 7" lower. When using a 9.17" lower and the 3.25" I was seeing 20-21psi at just 4k-4.5k rpms.

Was suggested to try an 8" lower or a 4.0" upper to get around -4-5psi.

[GT-ER]

If you already have a 9.17 lower, just use a 3.75" upper and you should be at around 15psi with your setup.

Saludos Charlie!

[Charlie540i]

Originally Posted by GT-ER

If you already have a 9.17 lower, just use a 3.75" upper and you should be at around 15psi with your setup.

Saludos Charlie!

I'll try the 3.75"....

Yo sabia que habia visto ese nombre antes! Saludos!!!

[GT-ER]

Originally Posted by Charlie540i

I'll try the 3.75"....

Yo sabia que habia visto ese nombre antes! Saludos!!!

LOL.

[mauldin44]

I'm running a 9.1 lower and 3.25 upper hitting about 18-19PSI of boost on a Whipple. I'm running Meth and E85 as well. I've learned with swapping pulleys to get boost numbers up or down it's kind of an art versus an exact science. Two cars can have the same pulleys, but vary on boost levels.