2.8" vs 2.9" pulley - Cobalt SS Network



2.0L LSJ Performance Tech 205hp Supercharged SS tuner version. 200 lb-ft of torque
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Old 07-05-2017, 05:30 PM   #1
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2.8" vs 2.9" pulley

Alright guys, I'm getting the zzp stage 3 kit very soon. My question is in the title, should I get the 2.8" or 2.9" pulley? I have zzp cai, long tube header and down pipe, and a cat back. My cooling mods will be the zzp heat exchanger and I'm also getting dual pass. I plan to install option b in the future but it will not be on the car when I down size the pulley. I always have access to 93 octane in my area. Oh and also it is my daily driver for the time being. I've been looking and looking for awhile now on information about which size will be better for me but I haven't been able to come to a conclusion.
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Old 07-05-2017, 07:38 PM   #2
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What size injectors?
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Old 07-05-2017, 07:40 PM   #3
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60lb
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Old 07-05-2017, 07:41 PM   #4
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There's not really a power difference you will feel. Just pick one lol
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Old 07-06-2017, 12:30 AM   #5
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There's not really a power difference you will feel. Just pick one lol
Yup. Just make sure to do supporting mods cause you will heat soak like a **** after a couple pulls. New ic pump and cobra h/e was my set up on my old irl.

I never did more than 3 back to back pulls and never beat it up when ambient temps were scorching and mainly drove at night so it was more than enough for me.

or just go turbo!
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Old 07-06-2017, 11:49 AM   #6
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At least you've got the exhaust done.... it's more important to get the Dual Pass first thought.
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Old 07-06-2017, 12:00 PM   #7
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So if everyone's agreeing there won't be much of a power difference I think I'll go with 2.9 just to be a little safer, unless anyone gets on here and gives a good reason for 2.8, I still have a few weeks until I can buy it so plenty of time for opinions lol. Thanks to everyone that's already replied!
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Old 07-06-2017, 12:17 PM   #8
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Go 2.7 and e85. Thank me later.
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Old 07-06-2017, 12:24 PM   #9
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Oh man I'd really love to do that, but there's not enough e pumps near me
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Old 07-06-2017, 01:07 PM   #10
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then go 2.7 with water/meth injection. been running that for the past 50k km, no issues whatsoever
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Old 07-06-2017, 01:44 PM   #11
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Too Inconvient to me. I don't want to rely on meth and have something malfunction and. It spray or something during a pull. Just me though.
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Old 07-07-2017, 12:43 AM   #12
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Too Inconvient to me. I don't want to rely on meth and have something malfunction and. It spray or something during a pull. Just me though.
cooling mods first then wideband, 60# injectors, 2.8, and tune.
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Old 07-07-2017, 01:21 AM   #13
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omg do cooling mods before it melts there is more then enough information on this site to answer any pulley question out there you just need to search and your first mod should be a wideband fueling is more important then post core temps
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Old 07-07-2017, 09:30 AM   #14
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Why would you not already have a wideband before tuning? You're going to tune without a wideband?
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Old 07-13-2017, 01:09 PM   #15
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2.8 crosses the line to full tilt finicky and easy to blow race application. 2.9 is the size for a driver that wants to drive with his right foot and not worry about going boom.
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Old 07-13-2017, 01:33 PM   #16
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I've been on a 2.7 pulley for almost 3 years. That's on a m62 and a tvs. I've taken 1000+ mile trips and tracked it a dozen times. Stock 2.4 motor and on e85 lol. Still runs amazing. "Easy to blow"
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Old 07-13-2017, 02:57 PM   #17
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2.8 crosses the line to full tilt finicky and easy to blow race application. 2.9 is the size for a driver that wants to drive with his right foot and not worry about going boom.
i would agree that this crosses the line between what you can get away with on a canned tune and when you need a proper tune. when i bought my car in 07 it had a 2.85 and 42lb injectors. in 2011 i did some more cooling mods, dropped to a 2.7 and put 60lb injectors in, and ive been running it ever since. its tuned slightly rich, timing is a little conservative, i keep an eye on the wideband, and keep my water/meth tank full. if you step on it and the wideband shows its lean, or doesnt feel like its pulling like it should, you lift.
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Old 07-13-2017, 03:20 PM   #18
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I've been on a 2.7 pulley for almost 3 years. That's on a m62 and a tvs. I've taken 1000+ mile trips and tracked it a dozen times. Stock 2.4 motor and on e85 lol. Still runs amazing. "Easy to blow"
Our 2.4's have 20% more cylinder capacity.
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Old 07-13-2017, 04:08 PM   #19
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Our 2.4's have 20% more cylinder capacity.
Ok my friend with an lsj has been on a 2.6 forever with no issues and before my friend went turbo he was on 2.5 lol
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Old 07-13-2017, 04:11 PM   #20
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ran a 2.7 with full cooling mods and water/meth for years before i went to TVS. We tuned it richer up top incase the water meth ever failed ( which it hasnt in over 6 years ) the motor would be fine. dont waste time on a 2.9, just do full cooling, a wideband and the 2.8. scangauge wouldnt hurt to have either. This setup was fine for many many highway pulls, plenty of trips down the strip at New england dragway. Installed around 65k miles and the car has about 130k on it now with another owner. no issues. Car has a 2.5 gallon tank in the trunk and only needed filling maybe twice a year, three times at most.
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Old 07-13-2017, 04:55 PM   #21
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ran a 2.7 with full cooling mods and water/meth for years before i went to TVS. We tuned it richer up top incase the water meth ever failed ( which it hasnt in over 6 years ) the motor would be fine. dont waste time on a 2.9, just do full cooling, a wideband and the 2.8. scangauge wouldnt hurt to have either. This setup was fine for many many highway pulls, plenty of trips down the strip at New england dragway. Installed around 65k miles and the car has about 130k on it now with another owner. no issues. Car has a 2.5 gallon tank in the trunk and only needed filling maybe twice a year, three times at most.
What size nozzle(s) was it running?
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Old 07-13-2017, 08:02 PM   #22
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whatever came with the snow performance stage 2 setup. we sprayed it pre blower which back then everyone thought ate the teflon off the rotors ( not true )

Last edited by 07MetallicSC; 07-13-2017 at 10:29 PM.
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Old 07-17-2017, 08:06 AM   #23
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ran a 2.7 with full cooling mods and water/meth for years before i went to TVS. We tuned it richer up top incase the water meth ever failed ( which it hasnt in over 6 years ) the motor would be fine. dont waste time on a 2.9, just do full cooling, a wideband and the 2.8. scangauge wouldnt hurt to have either. This setup was fine for many many highway pulls, plenty of trips down the strip at New england dragway. Installed around 65k miles and the car has about 130k on it now with another owner. no issues. Car has a 2.5 gallon tank in the trunk and only needed filling maybe twice a year, three times at most.
I wouldn't say don't waste time on a 2.9 pulley... More efficient gains can be had with a 2.9 pulley, ported head, and cams. My car was a prime example of that. This is not to say a small pulley car can't be made "efficient". The blower maps and how far you rev out with the smaller pulley will tell the tale.

I know most on here will never dig into the cylinder head or block for that matter, so the next simplest way to make decent power is a small pulley and loads of cooling mods. I chose to follow the build book, and it made for a very strong and reliable build.
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Old 07-17-2017, 04:34 PM   #24
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This is true. I was going on the assumption of not touching block or head as most dont do that.
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Old 07-18-2017, 10:32 AM   #25
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This is true. I was going on the assumption of not touching block or head as most dont do that.
Yup, I def agree with you and the smaller pulley for more torque in this case!

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