Procharger D1SC loud squeal & low boost
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Teching In
Joined: Apr 2026
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From: IN
Procharger D1SC loud squeal & low boost 02 CETA. Have a fully built forged motor, LS1, 38k miles on car. Bought from original owner 3 years ago. Pro built on Long Island by a shop that since closed.
D1SC has had a high squeal at constant RPM above 25mph or so. Put under heavy load or no load, seems to vanish. Have a 3.55 pulley on & only seeing 7psi max & blower is slightly overspun on occasion then.
I pulled the old manual tensioner plate, put on whole new set up from ProCharger with spring tensioner, including all pullies, still have both problems. When blower belt is off, went away. I removed head & changed oil. Was a bit low. Maybe 4oz vs needed 6, but I found no shavings in oil or on drain plug. Put in new oil, same 2 issues. Belts are all new too. Have the green belt on blower. No obvious play in the blower shaft. Spin by hand, no noise. Quite perplexed by both issues. No pulley interference either. Double checked & lowered sway bar 1". Also replaced original bov to Procharger Big Red.
I am perplexed. Also went & checked all hoses & pipes with intercooler & all tight. Did a leak test with my compressor & no noticeable leaks. I installed new boost gage but same readings. That & I know what boost feels like. Certainly the 7lb reading is correct.
https://youtube.com/shorts/KOQQ1XPusQY?is=5jROUkHpJySZabUp
D1SC has had a high squeal at constant RPM above 25mph or so. Put under heavy load or no load, seems to vanish. Have a 3.55 pulley on & only seeing 7psi max & blower is slightly overspun on occasion then.
I pulled the old manual tensioner plate, put on whole new set up from ProCharger with spring tensioner, including all pullies, still have both problems. When blower belt is off, went away. I removed head & changed oil. Was a bit low. Maybe 4oz vs needed 6, but I found no shavings in oil or on drain plug. Put in new oil, same 2 issues. Belts are all new too. Have the green belt on blower. No obvious play in the blower shaft. Spin by hand, no noise. Quite perplexed by both issues. No pulley interference either. Double checked & lowered sway bar 1". Also replaced original bov to Procharger Big Red.
I am perplexed. Also went & checked all hoses & pipes with intercooler & all tight. Did a leak test with my compressor & no noticeable leaks. I installed new boost gage but same readings. That & I know what boost feels like. Certainly the 7lb reading is correct.
https://youtube.com/shorts/KOQQ1XPusQY?is=5jROUkHpJySZabUp
Last edited by mhinchley; Jun 17, 2026 at 04:18 AM.
You will get some noise from the belt-is there a key in the drive pulley, so it's not spinning on the shaft. Have you data logged a run to see if you are WOT, sometimes folks think they are, but the data log doesn't lie.
Thread Starter
Teching In
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From: IN
yeah, key is there. I pulled it, cleaned shaft, reinstalled, while blower was off car & I changed oil in it.
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From: IN
there is some flutter when I let off gas for sure, but not under hard throttle. I checked that. To eliminate, I replaced original valve with big red. Vacuum is correct & changing. I can see it on my boost gauge.
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From: IN
How much boost would you expect to see with the D1sc & a 3.55 pulley? I talked to procharger tech & he told me blower was spinning slightly over max. I don't have a ton of experience with LS engines & blowers, but on my 331 motor with a Vortech T trim, I was seeing about 20 psi, spinning to max. Thought I'd see about that here, with this set up.
Last edited by mhinchley; Yesterday at 10:42 AM.
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Thread Starter
Teching In
Joined: Apr 2026
Posts: 11
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From: IN
I should add that car is built well & runs well. Has AFR heads, full headers, hooker 2.5" dual exhaust i just switced from magnaflow single 3", twin fuel pumps (I know cuz I changed them), good fuel pressure, no misfires, etc. Even has a full Moser rearend. Was definitely a high end build by original owner. Said build was $30k & that is why I bought the car. Paid $28 & couldn't do fast enough. I was looking for a GT500 when I came across this. It was winter, in NY so no test drive. Just loaded on trailer & left for Indiana.
Last edited by mhinchley; Yesterday at 12:57 PM.
Something is up, but if you ruled out the reference to the BOV then I'm not sure. I figure you should be close to 12 psi depending on how efficient your heads/cam/exhaust set up is.
Never been a fan of the BOV placement on the fbody kits but I understand that they are limited for space as it is on this platform.
Reach out to Bob and pick his brain. He's a cool guy to deal with.
Never been a fan of the BOV placement on the fbody kits but I understand that they are limited for space as it is on this platform.
Reach out to Bob and pick his brain. He's a cool guy to deal with.
So, the belt should not be squealing period, are you sure you don't have one of the Procharger units with straight cut gears which will make way more noise and sound like belt squeal? (stupid question but had to eliminate it) Boost is relative to engine design, a small engine with small port heads and a small cam will take more boost to hit the same number as a larger displacement engine with large high flow heads like the TFS heads. You've got high flowing heads and a fast intake which help, but I think you should still probably see more than 7 psi on a LS1, have you considered a grip tech pulley for the blower? My car used to be a blower car with a D1SC and with the small pulley it would see 14-15 psi but belt slip was a big problem. Also is the crank pulley pinned to the crankshaft? Also consider buy a laser pulley alignment tool and make all your pulleys are lined up, you can get one off amazon and return it when your done lol. My current car would throw belts at high rpm because the pulley alignment was off a little. Another stupid question, are you sure the belt routing is correct? Have any or the accessories been moved around changing the belt routing? Does everything spin freely when the belt is not on?
Just thinking out loud here.
Just thinking out loud here.
Thread Starter
Teching In
Joined: Apr 2026
Posts: 11
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From: IN
So, the belt should not be squealing period, are you sure you don't have one of the Procharger units with straight cut gears which will make way more noise and sound like belt squeal? (stupid question but had to eliminate it) Boost is relative to engine design, a small engine with small port heads and a small cam will take more boost to hit the same number as a larger displacement engine with large high flow heads like the TFS heads. You've got high flowing heads and a fast intake which help, but I think you should still probably see more than 7 psi on a LS1, have you considered a grip tech pulley for the blower? My car used to be a blower car with a D1SC and with the small pulley it would see 14-15 psi but belt slip was a big problem. Also is the crank pulley pinned to the crankshaft? Also consider buy a laser pulley alignment tool and make all your pulleys are lined up, you can get one off amazon and return it when your done lol. My current car would throw belts at high rpm because the pulley alignment was off a little. Another stupid question, are you sure the belt routing is correct? Have any or the accessories been moved around changing the belt routing? Does everything spin freely when the belt is not on?
Just thinking out loud here.
Just thinking out loud here.
Yeah, I checked belt routing & replaced all 3 of them. When I ran it without the supercharger belt, the noise went away. Ill try it again next week. Just set my pinion angle & found a broken year shock, so waiting on new ones. Probably from me letting rear end hang while changing driveshafts & had to remove broken Spohn brace to weld it. I broke it going 1-2-1, messing with a new Corvette. I lost. 🤣
Last edited by mhinchley; Yesterday at 02:54 PM.
Certainly not the belt. Had it tight with manual tensioner & now same with spring tensioner. New green belt now too. I sprayed it with belt dressing, no change. I thought it may be a pulley bearing but those are all new too now. It was low on oil, so must leak a bit or why would it have been low? I can't get it to do it much at idle so makes it harder to diagnose. Straight cut gears is a possibility but I would think it would be noisy all the time & not just at steady rpm. Then again, also have the low boost issue too. The noise & low boost makes me think something is wrong. Probably gonna pull it & send it in, have inspected & hopefully rebuilt. If beyond rebuild, guess Ill upgrade to an F1, yank nitrous off, & just run more boost........Been thinking about that anyway. Not really a nitrous fan. Original owner only had nitrous put on to purge at ricer peeps on Long Island. He had it tuned, but never used it himself either.
Yeah, I checked belt routing & replaced all 3 of them. When I ran it without the supercharger belt, the noise went away. Ill try it again next week. Just set my pinion angle & found a broken year shock, so waiting on new ones. Probably from me letting rear end hang while changing driveshafts & had to remove broken Spohn brace to weld it. I broke it going 1-2-1, messing with a new Corvette. I lost. 🤣
Yeah, I checked belt routing & replaced all 3 of them. When I ran it without the supercharger belt, the noise went away. Ill try it again next week. Just set my pinion angle & found a broken year shock, so waiting on new ones. Probably from me letting rear end hang while changing driveshafts & had to remove broken Spohn brace to weld it. I broke it going 1-2-1, messing with a new Corvette. I lost. 🤣
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From: IN
I inspected it pretty thoroughly & no wobble, no evidence that it has moved. I used a borescope to inspect 360* around the rear. Also a pro shop did the entire build, so I am comfortable saying they pinned it. All the work they did, that I have inspected is done well & all high quality parts. Also the belts are new & no wear on the edges of any of them, no belt dust, so pretty confident that everything is aligned properly.
Last edited by mhinchley; Today at 12:22 AM.
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From: IN
Kaltech was the shop that built the car. I was told the guy was too good & thorough & shop was losing money due to investing too much time into each car. I found the guy on Facebook & inquired, but he never responded. Original owner did not know much about cars & why he had a shop build it. Unfortunately, when he moved, he lost all the paperwork & not being a car guy, couldn't recall many of the parts or specs.
I found his grand opening thread in 2006.
https://www.smokinvette.com/threads/kaltech-tuning-performance-new-long-island-shop.1753/?utm_source=google&utm_medium=organic
Via a quick search Kaltech was quite popular on many car forums, including this one.
Last edited by mhinchley; Today at 01:00 AM.