Why is everyone scared to rev past 6K with heads/cam cars?
10-02-2006, 06:01 PM
#1
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Location: Ocala, Florida
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Why is everyone scared to rev past 6K with heads/cam cars?
I keep reading posts where people don't want to rev past 6K doing heads/cam instals and was wondering why everyone thinks the motor will blow reving past 6K. Hell I'm on the stock bottom end with a heads/cam car reving to 6500 on a 150 shot. 
Is the stock bottom end really taht weak? 
Is the stock bottom end really taht weak?
10-02-2006, 06:23 PM
#4
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
My 388ci LT1 untuned will rev up to 6,200 but im not scared, and the higher the rpm doesnt neccesarily mean that's where your power is. It depends on the setup and the cam. My last engine made power @ 5,500 so that's where I shifted. It's some people that over rev their cars and wonder why they are so slow.
10-02-2006, 06:43 PM
#5
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
I've read that past 6k you chance the bottom end coming apart. I have revved mine.... Well at least 7k, pegged the needle for about 2-3seconds in a race. Car started lunging, looked down and noticed it. I like to spin mine up to ~6300. I've got no problems.
10-02-2006, 07:53 PM
#7
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
because of the tremendous stress of an unbalanced stock rotating assembly. By revving higher then the stock redline with a stock bottom doesn't mean you will blow up the engine right away but the chances of throwing a rod or spinning a bearing greatly increases. Just because you change up the valve train and heads doesn't mean its a full blown revving monster... or it'll be a full "blown" motor soon.
10-02-2006, 07:57 PM
#8
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
I just got my car tuned at C.A.M. by Jeff Creech friday. Reved it up to 7200. It has a forged bottom end but had no problems. Peak power didn't start dropping off until about 6800. I wouldn't want to rev a stock bottom end up too high past 6300 but if it's built right i wouldn't worry.
10-02-2006, 08:00 PM
#9
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
I think it is well documented that most LT1's will survive and live a long life if they are spun no higher than 6300 RPM. I have heard of few failures from LT4 camshaft equipped LT1's.
When spinning LT1's to 6500 and higher the odds are much more likely that the rod bearings or main bearings may fail. This is an even more valid statement if the engine has mileage and is used to seeing less than 6000 RPM. It is possible that a brand new zero mileage LT1 would stand a better chance of surviving 6500 RPM+.
The other thing hurting very high revving LT1's is the lack of 4 bolt mains for f-bodies. The bottom line is a stock short block spinning to 6500 RPM or higher is living on borrowed time. The best thing is to build a forged bottom end then rev it to the moon.
When spinning LT1's to 6500 and higher the odds are much more likely that the rod bearings or main bearings may fail. This is an even more valid statement if the engine has mileage and is used to seeing less than 6000 RPM. It is possible that a brand new zero mileage LT1 would stand a better chance of surviving 6500 RPM+.
The other thing hurting very high revving LT1's is the lack of 4 bolt mains for f-bodies. The bottom line is a stock short block spinning to 6500 RPM or higher is living on borrowed time. The best thing is to build a forged bottom end then rev it to the moon.
Last edited by wrd1972; 10-02-2006 at 08:04 PM.
10-02-2006, 08:39 PM
#10
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
Forging the bottom end doesnt mean you will be able to rev it higher. My 388 isnt even forged and I could rev as high as you. Also yes the unbalanced stock bottom ends will have trouble with revs and could eventually blow. If you have a built engine that is fully balanced then you shouldnt have much problems, plus I have floated pistons which will reduce friction. Another thing is the 2-bolt, 4-bolt stuff. Yes the 4-bolt is stronger but I've never ever seen or heard of an engine failing because of only having a 2-bolt main. It doesnt have nothing to do with that unless you are running a HUGE NITROUS application. I was going to do 4-bolt splayed but then I changed my mind because if it's built correctly the 2-bolt will hold up to just about anything. There are 2-bolt mains that are just as fast, if not faster than a 4-bolt main.
10-02-2006, 11:15 PM
#11
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
Originally Posted by speed_demon24
Hell I'm on the stock bottom end with a heads/cam car reving to 6500 on a 150 shot.
I did the same. these motors are tough as nails
10-03-2006, 02:56 AM
#14
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Re: Why is everyone scared to rev past 6K with heads/cam cars?
I always go to 7k rpm for years now, I never not go there 
atleast 6800 but almost always 7k, my dyno sheet is in my sig, stock bottom end, guess just depends how you rev it there, if you drop gears while reving there then yeah you're prolly gotta hurt it, but if you go through the whole rpm range before getting there (not downshifting) then you're better this way, plus use good castrol syntec 0-30 in there
At 7k I'm only making about 5rwhp less then 6600 where my peak is more less of 420rwhp sae.
atleast 6800 but almost always 7k, my dyno sheet is in my sig, stock bottom end, guess just depends how you rev it there, if you drop gears while reving there then yeah you're prolly gotta hurt it, but if you go through the whole rpm range before getting there (not downshifting) then you're better this way, plus use good castrol syntec 0-30 in there At 7k I'm only making about 5rwhp less then 6600 where my peak is more less of 420rwhp sae.
