Max Rev Limit ?
09-30-2005, 07:20 PM
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Max Rev Limit ? What is the Highest RPM you can safely spin a stock bottom 2000 LS1 ? My car shifts at 6,800 rpm. Redline is 6,900. Is this too much ? I have a complete Comp Cams Valvetrain (ie;springs,pushrods,timing chain,etc) I've Never had any problems but should I back It down a little ?
Last edited by NYC FRANK; 09-30-2005 at 07:25 PM.
09-30-2005, 08:33 PM
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Its kind of a crap shoot. You car probably didn't get the updated rod bolts like the later years did. unfortunately you never know when it might let go. How much do you think you'd lose by shifting at 6700? Got a dyno graph? You might not lose much.
09-30-2005, 09:37 PM
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Why would you want to spin that high with the cam you have?
I'd be you're running out of power way before 6800 rpm. You'd probably run faster shifting around 6500. You'd have to check your dyno graph to be sure though.
No point in pushing it if it doesn't make you faster, right?
I'd be you're running out of power way before 6800 rpm. You'd probably run faster shifting around 6500. You'd have to check your dyno graph to be sure though.
No point in pushing it if it doesn't make you faster, right?
09-30-2005, 10:00 PM
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I have my Dyno chart in front of me. From 5,500 rpm to 6,500 I'm making Max HP,It's pretty Flat. It starts to drop off after that but at 6,800 It's still making just a tick under 350 HP. Torque is down to only 280 by then ? I'm gonna lower it to 6,600 rpm or even 6,500. I'll see what It does at the track. Anyway It freaks me out to see the Tach go that far into the Red !
10-01-2005, 09:37 AM
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Totally different comparison, but Coates Engine company made a set of rotary valve heads for a Ford 302 and put them on a STOCK short block. Now, in normal setup, the 302 redlined around 5800 rpm. With the rotary valve heads(they don't have a camshaft, springs, or anything else that has to open and close under extreme pressure), they claimed that that same 302 short block could SAFELY spin up to 14,500 rpm.
With that in mind, it would seem that, other than the weaker rod bolts in 2000-back LS1s, the valvetrain is the limiting factor in how high you can tach, 'cuz at higher rpm, the pushrods are suspect, as well as the stock valvesprings. Just my $.02.
With that in mind, it would seem that, other than the weaker rod bolts in 2000-back LS1s, the valvetrain is the limiting factor in how high you can tach, 'cuz at higher rpm, the pushrods are suspect, as well as the stock valvesprings. Just my $.02.
10-01-2005, 11:20 AM
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Originally Posted by NYC FRANK
I have my Dyno chart in front of me. From 5,500 rpm to 6,500 I'm making Max HP,It's pretty Flat. It starts to drop off after that but at 6,800 It's still making just a tick under 350 HP. Torque is down to only 280 by then ? I'm gonna lower it to 6,600 rpm or even 6,500. I'll see what It does at the track. Anyway It freaks me out to see the Tach go that far into the Red !
Take your TQ number at 6500 rpm, multiply that by your 1st gear ratio. That will equal (X).
Then, take your TQ number at the same SPEED your car will be (MPH) as at 6500 rpm in 1st gear, only if you shifted to 2nd gear (probably aroun 4500 rpm in 2nd?), and multiply that by your 2nd gear ratio. That will equal (Y).
If (X) is greater than (Y). You should stay in 1st longer than 6500 rpm.
Then do the math for 6600 rpm in 1st, 6700 rpm.... etc.
At the point where (Y) is greater than (X), that is where you should shift.
Acceleration is an exact function of TQ and gearing. That's why this formula will work.