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Discussion Starter · #1 ·
Hey whats up all.. i was interested in raisning my rev limit, to get mroe power out of my blower........ and i was wondering how much higher i could rev it up safely on the stock head........

i know of 2 people raising their b18b's up to 8000rpm redline on the stock head.......but is that safe with out changing springs and retainers?


thanks for your time.
 

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the ls block was made to handle upto 7000rpms same goes with the valve springs......anything more will be dangerous and not worth it. beside you are putting alot of stress on the motor already with the supercharger.reving it to 8k on stock will cause your block to throw a rod or something....poor R/S ratio will cause this easily
 

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GreekSpeed said:
hmm i thought it had mostly to do with the head....


didnt know the block would be affected that much buy it....
The B18b head should not be revved beyond 8000 RPM, the B18C head can safely handle 8500. Remember, the longer you rev at that speed the more chance you have to float the valves... especially with boost.

The bottom end's weakness is the rods. At such a high RPM, the tensile strength may not be enough to handle the loads. Remember the rods are stressed more at 9000 RPM on an N/A motor than they are at 6000 RPM boosted. Simply removing the casting flaws (and any other stress risers) on the stock rods and further shotpeening them greatly improves their strength.

Also, the B18b has a longer stroke which further stresses the rods at high RPM. Build that motor to make its power below 7000 RPM.
 

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Discussion Starter · #9 ·
PupaScoopa said:
The B18b head should not be revved beyond 8000 RPM, the B18C head can safely handle 8500. Remember, the longer you rev at that speed the more chance you have to float the valves... especially with boost.

The bottom end's weakness is the rods. At such a high RPM, the tensile strength may not be enough to handle the loads. Remember the rods are stressed more at 9000 RPM on an N/A motor than they are at 6000 RPM boosted. Simply removing the casting flaws (and any other stress risers) on the stock rods and further shotpeening them greatly improves their strength.

Also, the B18b has a longer stroke which further stresses the rods at high RPM. Build that motor to make its power below 7000 RPM.

how do u suggest i build my motor up to keep its peek power at sub-7000 rpm's?

lower compression? higher compression? hmmmm...
 

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Considering what you have, the roots blower tends to make power across a broad range instead of being very peaky. Typically, using short intake runners, proper headwork, and rod/stroke ratio allows one to tune the motor at different RPM ranges.

You should not raise static compression on a supercharged motor, it's already very high as it is!
 

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Everyone keeps talking about raises redlines but what is really the point if you're not making power up there. You'll need some aftermarket cams that actually make power past stock redline or otherwise its just wearing your motor and slowing you down. Rather than raise your redline why not invest in your turbo cams.

Edit: I mean FI cams....
 
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