Stock engine and Procharger
12-14-2007, 10:26 AM
#1
Stock engine and Procharger I'm currently getting a SDCE D1SC 7-9 psi kit put on my Camaro that still has a stock engine. I've read that the APS TT kit recommends stiffer valve springs, why is that and why doesn't the same recommendation apply to a supercharged car that's making the same amount of boost as the TT?
My goal is a safe and reliable 500 rwhp for a few years, then an engine rebuild and up the boost for 650 rwhp.
My goal is a safe and reliable 500 rwhp for a few years, then an engine rebuild and up the boost for 650 rwhp.
12-14-2007, 12:22 PM
#3
To spring or not to spring - that is the question This thread says it is recommended in the sticky, then master Bob says this:
Yes, you should have no problems with 8lbs of boost. We installed an ATI ProCharger D-1SC on my '99Z28 when it had 110,000 miles on the internally untouched engine. My car is in my project car section of my website. The engine held up just fine, stock valvesprings and all. Bob
12-14-2007, 12:31 PM
#4
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https://ls1tech.com/forums/showthread.php?t=821215
This thread says it is recommended in the sticky, then master Bob says this:
Is it just one of those things that you should do just to be on the "safe" side? I don't want to throw away money on this engine since I have plans to rebuild it later on.
This thread says it is recommended in the sticky, then master Bob says this:
Is it just one of those things that you should do just to be on the "safe" side? I don't want to throw away money on this engine since I have plans to rebuild it later on.
12-14-2007, 03:03 PM
#6
That's a good point. But I have to ask would you put 2 yr old valve springs into a brand new $8k motor? I'm not going to rev the crap out of it as I normally shift around 5800 so I should be alright not changing them. I was just wondering if there were any horror stories out there that would change my mind. If Bob says I shouldn't worry about it then it should be fine.
I'm more worried about grenading my stock 10-bolt.
12-14-2007, 08:41 PM
#7
We've only had one car that we truly had problems with the stock valvesprings. We had installed an ATI ProCharger D-1SC on a customer's T/A, who regularly beat the snot out of this car. He brought the car in to us with an engine misfire, we did all the common things first. Replaced spark plugs, wires, swapped coils around. Sometimes the misfire would change cylinders! It turned out to be totally shot valvesprings, we pulled them out and put them on a plate of glass, and they were all at different heights. This car had 36,000 miles on it, and the guy (he's now in prison) apparently would hit first instead of third every now and then. We've never had one of these cars drop a valve, never. Bob
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12-14-2007, 10:22 PM
#8
Part of the reason better valve springs are recommended is because you are applying whatever boost pressure you run to the entire intake system, including the back (top side) of the intake valves. If you do the math, the area of the top side of the valve is roughly around 3 square inches. Apply 10 psi to that and you now have 30 lbs trying to open that valve when it is seated.
12-15-2007, 10:27 AM
#9
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We've only had one car that we truly had problems with the stock valvesprings. We had installed an ATI ProCharger D-1SC on a customer's T/A, who regularly beat the snot out of this car. He brought the car in to us with an engine misfire, we did all the common things first. Replaced spark plugs, wires, swapped coils around. Sometimes the misfire would change cylinders! It turned out to be totally shot valvesprings, we pulled them out and put them on a plate of glass, and they were all at different heights. This car had 36,000 miles on it, and the guy (he's now in prison) apparently would hit first instead of third every now and then. We've never had one of these cars drop a valve, never. Bob
Sorry, couldn't resist
12-15-2007, 11:38 AM
#10
Part of the reason better valve springs are recommended is because you are applying whatever boost pressure you run to the entire intake system, including the back (top side) of the intake valves. If you do the math, the area of the top side of the valve is roughly around 3 square inches. Apply 10 psi to that and you now have 30 lbs trying to open that valve when it is seated.
Bob, it's good to know that you haven't seen engine damage for not doing springs. I admit that I've also hit 1st going to 3rd a few times in my car's 30k miles. Now with 7-9 psi of boost (don't know yet) I would imagine the gears are going to wrap out that much faster, making it harder to hit the shifts perfectly every time. The car will see some track duty for sure when Ennis opens back up in the spring.
12-20-2007, 04:48 AM
#11
Thanks for the explanation, sleeper, that makes a lot of sense... So to counteract the 30 lbs. of open force, the valve train needs springs that have 30 lbs more seat pressure than the cam needs when used NA. I guess there could be some valve float at high RPMs without changing springs, which could manifest itself as some loss of power.
Bob, it's good to know that you haven't seen engine damage for not doing springs. I admit that I've also hit 1st going to 3rd a few times in my car's 30k miles. Now with 7-9 psi of boost (don't know yet) I would imagine the gears are going to wrap out that much faster, making it harder to hit the shifts perfectly every time. The car will see some track duty for sure when Ennis opens back up in the spring.
Bob, it's good to know that you haven't seen engine damage for not doing springs. I admit that I've also hit 1st going to 3rd a few times in my car's 30k miles. Now with 7-9 psi of boost (don't know yet) I would imagine the gears are going to wrap out that much faster, making it harder to hit the shifts perfectly every time. The car will see some track duty for sure when Ennis opens back up in the spring.
