Quick and simple question. When turbocharging a car is it necessary for the head to support high rev limits(8500 or above) or just a descent rev limit. i.e. the overall rev limit on an LS motor. By the way how high does an LS rev?

 

I usually run stock LS engines to 7500 and LS with built heads to 8000.

jason

 

i wouldnt take a LS past 7500. even then, youll hit the rev limiter so youll need to get a MSD amp with an adjustabel rev limiter. redline is at 6900 on LSs.

 

 

dizzam...7500 RPM on a stock LS WITH a turbo? I wouldn't even try that....once.

I shift my non F/I b18b at 6500 RPM...it has no power, and sounds like it's wheezing any higher than that...

I'd rev no higher than 6800.

generally, when turbo, just like stock, you don't rev higher than you would normally unless you're built.....or insane.

 

factory rev limits are conservative the same way they build the engines stronger then nesseccary so they will last a long time. with boost ur already shortening the life of the bottem end, so with RPM's youll just be shorting the life of the head too. im already revving my LS to 7100(fuel cut) and when i go hondata i plan to rev to 7400 if it makes power up there. I figure im already gonna blow the block from too much boost, why not blow the head up at the same time and make the motor swap easier on me.. hehe jk, but really. if u want ur motor to last a long time keep the RPM's down. I think Larry from ENDYN once referred to R.P.M's as Ruins Peoples Motors. If ur willing to take the chance and ur motor makes power up there go for it, just dont abuse it.

 

hahaha

 

i revved all of mine till they started dropping in power. My last one may it rest in peace made power till 9200 till the crank walked and destroyed everything.

 

we've been taking b20's (N/A and turbo) to 8500 on the 1-2 shift and to about 8200 in 2nd, 3rd, and 4th. thats with springs and retainers. blows away a stock ls rev limit.

 

Now to all you guys that said that revving this engine past 8,000(that being the highest I heard) and that coming from a built head. If I build the whole damn block it should blow up right? I'm talking about giving it a 5 angle valve job ported and polish intake and exhaust valves. YOU know the works...So i think I should be fine. Oh yeah what advantages can I expect from boring the block to let's say 84mm from the stock 81 and then adding darton or eagle sleeves. After that's all said and done I would think that would be a pretty well put together engine if I don't say myself. Oh yeah and I will have all the turbo goodies lower compression pistos, forged rods, and a whole complete new valvetrain. How does that sound ??

 

i always run a balanced stock crank with Crower rods and i go with 85mm pistons. AS far as the head its jsut Crower off the shelf springs and retainers. i have had every cam Crower makes and i have had a few WEB cams in there. I dont think the problem is in the block, its in the head. Even still i just decided to go vtec cause i did get uncomfortable with the rocker arms on the LS at over 9K. I have broke a few of them but have never done any damage.

 

THANKS A MILLION TO ALL THE GUYS WHO GAVE ME THE HELPFUL INFO

 

I take my stock LS to 7400 on occasion.
New stock sleeved built bottom end in the works with some help from boosted3g (Thanks Josh!) and throwing in some crower springs and retainers. Gonna take it to 8500 or so when Im done. Mainly to see what gear I go through the traps at.

 

However feets like this built LS or not your killing the life of your dialy driven b18b aren't you.....?


[Modified by shadowdawn, 10:56 PM 8/20/2002]

 

Dont raise rev limits and rev to crazy levels... just shove more usable power under the curve you have now.....

why stress a motor at 9000 rpm and make 400hp when you can do it at 7000rpm and make 400hp....

(just rough numbers but youget the point)....

No need to rev crazy, just build it with the right parts so you get more power in the limits of what you have....

 

i don't realy understand your comment but it seems as though your worried about the life of the motor. i personally have yet to see a LS or b20 blow from reving to 8200 with springs and retainers. as long as its tuned right. i mean, its not like your taking it there everyday. you do it when you have to. if you rag the car, it will last only so long. not to mention, the b18 and b20 blocks are relatively cheap. then again, i rev my b18c1 to 9800. he he.

 

GSRwBOOST> That is probably the most intelligent thing I've heard all night. That is why I made the comment about people being VTEC crazy. Correct me if I'm wrong high rev limits are not a necessity to make serious numbers on the dyno. Isn't it about how efficient(meaning where in the rpm range) the car is making the numbers. And from my understanding the lower the rpm the less stress on the engine. And that is why I chose the LS it makes although 3 or so less lbs/torque less than the GS-R and 7 or so less than the type R it makes that torque at a 1,000-2,000 rpms less than those mighty VTEC engines. And some say that VTEC is not a favorable characteristic for turbocharging. I mean correct if I'm wrong the constant flow of the non-VTEC LS head is a good characteristic for turbocharging.

EAT THAT YOU VTEC GROUPIES!