How to rev higher?

Gatsby · 10-24-2009, 02:58 PM

I have some pretty newbie questions that were not answered clearly in the search or the stickies. Should be pretty easy for the resident experts.

What keeps an engine from revving higher? I know there are rev limiters (what are ours set for on a stock LS1?) that limit it, but what keeps it from physically or mechanically revving higher and is it always beneficial to get some more RPM's out of it?

Obviously torque will drop at a certain point, but our engines produce power beyond our rev limiter for durability sake (i'm assuming).

What factors have the biggest impact on our cars not revving higher and how can i get it to rev higher? I'm guessing valvetrain, engine internals, fuel system, and ignition all affect it, but are all those things as important as the next?

I'll be doing a cam swap in the next few months and was wondering if upgraded springs and pushrods and the little valvetrain accessories will allow the engine to rev higher than it does now.

What is everyone revving to on an auto with a stall converter in the 32-4400 range?

If you have taller gears (3.90-4.10) and you could rev higher, would it allow you to run that taller gear without running into OD easier (in the 1/4)?

Just trying to iron out my knowledge without guessing at things, thank you all.

lemons12 · 10-24-2009, 03:11 PM

Short answer here, on my way out to work..

You should be shifting around 6300 RPMs and limiter should be raised (by a tuner, handheld or dyno) to around 6600 RPMs.

Rod bolts are a very weak link and are reall strained in the higher RPMs, also stock push rods have a hard time in the higher RPMs.

Hope that helped, sorry so short.

Gatsby · 10-24-2009, 04:18 PM

That was helpful, thank you.

What is the stock shift point/rev limiter? And is it a good idea to increase them on my current mods (in sig). Or should I wait until I get some supporting things like springs, rod bolts, etc?

cbr600rx7 · 10-24-2009, 05:24 PM

Cam, Valve springs, and a good tune and you should be safe up to around 6800 some guys do push a little past that but i would strongly recomend rod bolts at that point.

Dom · 10-24-2009, 08:37 PM

I'll ditto what the others have said. First thing to physically limit the rev limit is valve springs. They probably float already at the stock limiter. Next would be rod bolts. I'm not sure on the limit of those. I was kinda curious myself.

KILLER-LS1 · 10-24-2009, 10:20 PM

reducing valvetrain weight while increasing the strength will let you rev higher. do a dual valvespring with titanium retainers, lightweight rockers, titanium valves, chromoly pushrods etc and you could rev into the low 7's if you wanted. (even though it may not be beneficial)

BADD SS · 10-24-2009, 10:36 PM

Quote:

Originally Posted by KILLER-LS1

reducing valvetrain weight while increasing the strength will let you rev higher. do a dual valvespring with titanium retainers, lightweight rockers, titanium valves, chromoly pushrods etc and you could rev into the low 7's if you wanted. (even though it may not be beneficial)

You do not need lightweight rockers, or titanium valves to run low 7k's. I ran 7100-7400rpm with no issues for a while now. I have rodbolts, imo thats a must, valvesprings, good pushrods. Next setup will be a single plane, much higher rpm, and for that, im going titanium valves...

fwiw, for a mild h/c setup that I have, with 4.56 gears, 7100 rpm shifts gave me the best times. Higher stayed the same, and lower lost time.

eseibel67 · 10-24-2009, 11:10 PM

Stock limit is 6200 RPM.

Crank360 · 10-24-2009, 11:23 PM

Quote:

Originally Posted by KILLER-LS1

reducing valvetrain weight while increasing the strength will let you rev higher. do a dual valvespring with titanium retainers, lightweight rockers, titanium valves, chromoly pushrods etc and you could rev into the low 7's if you wanted. (even though it may not be beneficial)

This^ plus solid lifters(just in case).

Dom · 10-25-2009, 12:12 AM

Quote:

Originally Posted by KILLER-LS1

reducing valvetrain weight while increasing the strength will let you rev higher. do a dual valvespring with titanium retainers, lightweight rockers, titanium valves, chromoly pushrods etc and you could rev into the low 7's if you wanted. (even though it may not be beneficial)

First you said reducing valvetrain weight and then you said dual valvesprings. Dual valvesprings adds weight. I would stick with a mild lobe and use single beehive spring like PAC 1518.

lemons12 · 10-25-2009, 03:40 AM

Whether you have a cam or not if you are wanting to raise the limiter I would replace springs and pushrods.. They are cheap, you will need them later anyways, and they are easy to install.
Just added precaution is all.

SOMbitch · 10-25-2009, 05:10 AM

FWIW on a stock cam you will gain NOTHING but extra wear and tear by spinning higher...

2nd on stock 99 rodbolts even after the other valvetrain upgrades I would not spin it over 6500. 01-02's can safely spin a little higher due to better RB's

3rd some on here will disagree on this but if you just drop the pan and install better rodbolts I would only use Katech's. They are the only aftermarket RB designed as a direct replacement. That is all I'll say as there is tons of info on this subject if you search on here......

Gatsby · 10-25-2009, 08:32 AM

Thanks folks, this has all helped a bunch. I knew I'd wait for a cam, just wondering what there is to gain.

Johnnystock · 10-25-2009, 08:44 PM

Quote:

Originally Posted by Crank360

This^ plus solid lifters(just in case).

You would need new lifters/rockers/PRs/cam then, and its not worth going solid roller for a street setup IMO. You can get astounding results with hyd setup with gen III engines.

Quote:

Originally Posted by Dom

First you said reducing valvetrain weight and then you said dual valvesprings. Dual valvesprings adds weight. I would stick with a mild lobe and use single beehive spring like PAC 1518.

True. Should only go double spring for high lift cams like 615+ lift.

Quote:

Originally Posted by SOMbitch

FWIW on a stock cam you will gain NOTHING but extra wear and tear by spinning higher...

2nd on stock 99 rodbolts even after the other valvetrain upgrades I would not spin it over 6500. 01-02's can safely spin a little higher due to better RB's

3rd some on here will disagree on this but if you just drop the pan and install better rodbolts I would only use Katech's. They are the only aftermarket RB designed as a direct replacement. That is all I'll say as there is tons of info on this subject if you search on here......

I think ARP has some RBs that did past the test of abuse.

I was hoping that someone would be clear on the subject for the OP SOMbitch was; stock cam is good for the stock range it has. Just look at the LS6 cam in the Z06; it has more top end, but you need better springs already to support it plus its matched with the LS6 intake/heads, a lot better than the LS1 intake/heads.

The cam is the brain that will dictate at first were your powerband will be, after that, its all in the other parts around it; intake, heads, displacement, valvetrain,etc.