I want to be able to cross the traps at the track in 3rd, which i calculated is about 6300 rpm for me. I've already done this about 4 times on the stock valvetrain and i dont want to do it again without upgrading some stuff.

Heres the combination im thinking of doing:
- stock cam
- 1.6rr (self-aligning, havent settled on a brand)
- comp o.e. replacement lifters
- comp hardend pushrods
- GM LT4 valvesprings

Do ya'll think i would have issues running this setup to 6300 rpm?
or should i look into a stiffer spring or the comp R lifters?

thanks!

 

There is no reason to rev that high with a stock cam, you will be slower.

 

Thats what i always thought, but i tried doing it a few times and it dropped me from running a consistant 14.1 in the quarter to a consistant 13.9

 

You shouldn't need the r lifters with a stock cam even with 1.6 rr. If you have springs that run with higher pressures you then run the risk of collapsing the lifter . A strong spring would definately do you well, though. My cam has .569 int .577exh using 1.6 rr and I am using a new comp stock replacement (850-16) lifters. I am using 987 double valve springs and Llyod Elliot said I should be good with this set up. In my 383 this cam will run good to about 6300 before it drops off.

 

thats good news, i wanted to stick to basic oem stuff as much as possible ( and i heard the comp Rs can be noisy)

I figured everything would be ok, since all the componets i would be using are >= in strength to the GM LT4 valvetrain components, which i think are supposed to be good to at least 6200rpm.

 

the thing with the comp R is that the valve lash is different. With oem lifters anywhere from 1/4 to 1/2 past zero is acceptable. The comp R lifter has a valve lash of .002-.004 or aprox. 1/16 of a turn past zero. Too much past and you limit rpm and eat horsepower quick.

 

if you are gaining that much by spinning it higher, i would guess A.) you dont have stock cam and dont know it or B.) are on the slower side with the clutch

In no way trying to be a dick, but no way a stock cam is making any power up there. Could just be that the extra gear change is costing you

 

yeah, sounds like a little practice with the 6 speed and a short shifter if you don't already have one would be a better investment in your time and money.

 

I cuncur, (If you actually have a stock cam.) Like everyone else has said, no WAY 6300 with a stock cam will get you that much.

 

I agree with the guys here. You're gaining the time from making one less shift. If you want to keep the stock cam, then i think you would be better off getting some more gear and not revving it so much. That way, you'll cross the traps much higher in fourth, and i guarantee you'll gain some time. However, it might be worthwile to throw those lt4 springs on your heads anyway, depending on what kind of milage you have, and whether or not you have the original valve springs.

 

I have a stock cam, and my optimal shift point is 6000 rpm. It all depends on your top end HP gains over stock. My headers, catback and CAI gave me enough top end to move my optimal shift point from 5700 rpm to 6000 rpm. Once I put the 1.6 RR's in, it might even bump up to 6100-6200.

I totally agree with you though, for an entirely stock engine, the 5700 rpm redline works out to be the optimal shift point.

Almost any aftermarket cam moves the optimal shift point out of the rev range of our motors, even the Hotcam. We end up shifting based on valvetrain stability, rather than the optimal points based on our dyno chart.

To the original poster, if you want to spin high all the time, the NSA RR's are much safer than the SA rockers. Of coarse you need to use them with the GM guideplates and hardened pushrods, but high RPM stability is MUCH better with a NSA setup.

Dan

 

With most the bolt ons i was shifting mine at 5900, 6k somewhere in there. Going past that to 6300 is a big difference though.

 

Agreed. Very True.

Dan

 

Mods i have are k&n, edelbrock shorty headers and a borla cat back

285 rwhp/ 312rwtq
Ive got a decent dyno graph somewhere will my hp/tq above 5500 that i will try to locate.

While my power does drop off significantly on the high end, my optimimum shift point always came out very close to 6200 rpm when i figured it out (figured this out after doing ALOT of work in excel determining where the torque curves for each gear intersect)

I'm pretty good at shifting, and 3-4 has never been a particularly difficult experience for me. My previous best times were obtained powershifting all gears at 5900 rpm. While i agree that removing the 3-4 shift could have contributed to the better times, i think the main reason is that i was still making more torque at the wheels in 3rd than in 4th at 5900-6200 rpm. Hence my desire to upgrade the valvetrain.

 

I hear you about the Excel calculation. Been there. Doing that.

You have my feedback regarding this topic.

Dan