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Discussion Starter · #1 ·
Currently using a 2.38 upper with stock lower.. Getting 15.5-16psi. About to go with a cam so Im going to replace the dampener with ATI. Saw lots of threads on this, but nothing concrete. Im just wanting the same boost as I am seeing now. Was thinking 2.38/9.1? I do have a 2.55 upper that can be used if it makes it easier to achieve what I'm looking for. Maybe 2.55/9.55? Car is a FBO car.. Stock blower & snout. Thanks for the help!
 

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i was running 2.4/9.17 with id1300's, ZL1 lid, 90mm tb, weapon x heat exchanger, 8 gal trunk tank. Butt dyno said FAST but never got the chance to dyno it.
 

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Discussion Starter · #6 ·
What cooling mods?
ZL1 Lid, BMR Ice tank, & C&R H/X, & Hi-Flo H/X pump

An 8.6 lower will bring you up to a 3.6 ratio. Id stop there
Your probably right.. I believe right now I'm at 3.3 ratio, so going with 8.6 will bring ratio up (3.6) & make up for boost loss with cam. Any idea what the correct belt size is with the 2.38/8.6 combo? I also have a 100mm idler pulley.
 

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2.38/8.6 here at 14ish PSI with ported heads/cam/2" headers.

Less boost with more power is the way.
 

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2011 CTS-V Coupe with a blue wrap. Cam, smaller pulley, larger injectors, methanol injection.
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UH OH, I feel like I'm about to be shamed and or banned forever from this site. Either way, it was fun while it lasted.

I too have a 2.38 upper pulley but with stock lower. I thought I was through with mods and am very happy with my car like it is. It has a small cam upgrade, larger injectors, 1 7/8 headers, methanol injection, reinforced brick, upgraded heat exchanger but not sure what it is. It was on the car when I bought it. I'm currently at 15 psi and I dyno'd at 664 / 621. I'm more than o.k. with how this thing pulls on the highway. It feel like a beast. Is it bad to leave the ratio that I have? I honestly thought I was through with upgrades till my motor blew. Is a 2.38 and a stock lower pulley a bad setup? All I've ever had until this year are turbo'd supras. I've never dealt with pulley ratio's.
 

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UH OH, I feel like I'm about to be shamed and or banned forever from this site. Either way, it was fun while it lasted.

I too have a 2.38 upper pulley but with stock lower. I thought I was through with mods and am very happy with my car like it is. It has a small cam upgrade, larger injectors, 1 7/8 headers, methanol injection, reinforced brick, upgraded heat exchanger but not sure what it is. It was on the car when I bought it. I'm currently at 15 psi and I dyno'd at 664 / 621. I'm more than o.k. with how this thing pulls on the highway. It feel like a beast. Is it bad to leave the ratio that I have? I honestly thought I was through with upgrades till my motor blew. Is a 2.38 and a stock lower pulley a bad setup? All I've ever had until this year are turbo'd supras. I've never dealt with pulley ratio's.
That setup is fine. People normally upgrade the lower when they install a cam because it's basically free labor. When you install an ATI balancer you also prepare for the future because you can swap to a new pulley size without changing out the balancer. I have a 2.45 upper and just went 10% over on the lower with an 8.66. I'm at 704 on E85 without headers. That's plenty for this old man.
 
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2011 CTS-V Coupe with a blue wrap. Cam, smaller pulley, larger injectors, methanol injection.
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No need for more pulley unless you’re chasing a dyno number or trap speed/et.
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I'm not chasing anything, they're usually trying to catch me. So far, I'm 4-0......lol

I'm going to leave mine just like it is until she tears up and then I'll build her the right way. She's a handful now and I love it.
 

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I had mine on the highway for 208,000 miles. Unmodified. Best driving car I have ever had. Surprisingly SHO was the second. I would be afraid to put what you guys are doing on the highway. Looks like street or strip racing are what everyone seems to be doing. Right? Wrong?
 

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2011 CTS-V Coupe with a blue wrap. Cam, smaller pulley, larger injectors, methanol injection.
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I haven't taken mine to the strip. I plan on it, but I just haven't. I will occasionally race on the highway if an unsuspecting mustang or dodge pulls along side of me. Usually my tag warns them though. I'm thinking about changing it to something more subtle. GAPTIZD seems a bit blunt.
 

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2012 Cadillac CTS-V Sedan WDT
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I haven't taken mine to the strip. I plan on it, but I just haven't. I will occasionally race on the highway if an unsuspecting mustang or dodge pulls along side of me. Usually my tag warns them though. I'm thinking about changing it to something more subtle. GAPTIZD seems a bit blunt.
There is a guy in Pittsburgh with a z06 with that plate
 
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