32valves

I'm wondering if anyone actually knows what the LT5 is capable of rpm wise. Seems like if the factory trusted the 7k redline that 8k rpms would be ok (GM has BIG durability standards). Are there any components in the motor that if redesigned would allow more revs? I wonder what type of power an LT5 with max ported intake/heads and cammed for high rpm's would make? Discuss.

8388

I wouldn't want to push it beyond 7500.

32valves

doing some searching, I found a thread where people were saying similar things.....I guess the question is why not? The new LS7 is going to have a 7100 rpm limit and it's OHV. The Honda S2000 revs to 9k from the factory......if the LT5 could be rev'd higher it should make huge power.

90 Corvette ZR-1

most of the biger cube Z's hit 7200-7500. I know of a 350 cid that hits 8,000 from time to time.

W i l l

I believe the lifters reach a limitation at some point. FastLane used solid lifters to cure that problem.

8388

There's plenty of power to be made within the 7500 rpms on the LT5. If the big bucks (general motors) had continued funding the LT5 project. The engineers would have come up with better air flow designs. Which the LS engines have had to their benefit. Now it's up to just a few with limited funds to find the power.

MrCrowley

I agree with everyone as far as the 7500 limit, even though I have my rev limit set for 7650. I just don't wanna go beyond that. I also think the chains are a weak link in the system.

After dyno-tunning my car resently I do not rev mine past 7200. Its where I have peak power and my car ran great at the track shifting there. But bigger cams will shift things slightly higher also. Its good to have the extra rpm and that is always a good thing!

Get a shift light too as there is always alittle tolerance in the tach, and you wanna be sure you aren't stressing things too much.

Lane made the most power so far....Maybe Ron can give us some insight on what he has done!

cward

I asked Graham B. what I could pretty safely rev my Z to and he told me 8K. By accident, I reved #364 to about 10K and escaped with just a valve mark on the top of one piston. I also have run 180 in 5th with 4.10 gears. Tach said about 7500-7600 and I held it there for a couple of seconds. It never missed a lick. Also, when my speedo said 201, my tach was reading about 7400 in 5th with 3.45 gears. I held it there for about 3 miles. Based on those obs, I would say Graham is right. Obviously, it would take a modified engine to need to go to 8K. The engine in #364 was not highly modified but on the dyno, I would shut it off at about 7200 - 7300 and it was still pulling the same hp as it did at 6500. Very flat curve on that particular engine. My last chip had the rev limiter set at 7600.

Curtis

8388

201 mph with 25" tall tires and .75 on 3.45 should be around 7000 rpms. My 93 Z's tach seems a bit fast too.

cward

Tach was nearly dead on according to many dyno runs. Bob Hall and I have had several disscussions about how fast I was really going but since speedo said 201, that is all I ever claimed. Also radar said 201 but we don't know where the radar got me. I slowed down a couple of miles before the end of the straight and the radar could have been (and probably was) close to the end of the straight. Don't know for sure. Also don't know how fast I was really going. But that is why I always say that that is what the speedo was saying. I was running Hoosiers and am not sure of their height. I do Know I was going damn all fast. :-)

Curtis

RedRiderZR1

Speaking of Tachs. I was using datamaster to log the car and when I revved it up to 3500 RPM on the tach, datamaster showed 3000 RPM. If that is true then when I want to go to 7k RPM, I will have to hit 8k RPM on the tach. I had the car smogged last month and while it was hooked up I had the guy rev it up and hold it. Tach was reading high there too. 1k difference at 7k RPMs on mine it seems.

Greg

jabrun

The accessories on the front of the engine don't like extremely high RPMs. I'm trying to remember where I read that.

Rkreigh

I did a write up on "Life in the FastLane" that chronicals some of Lane Goldstein's adventures "the hard way" with his 900 hp 431 engine. he used deck plates with stretched liners and a full custom sheet metal intake and an electromotive Tec II computer along with custom chains, cams, and solid lifters to make power in the 8500-9k range.

this engine was torn down frequently to check it and each time he did he changed the chains for saftety after marking how many runs were on them.

According to Graham B. the sprockets are somewhat of a limiting factor as are the lifters which will indeed float somewhere between 7800-8200

I have smaked 8k a few times but the point is, unless the car can make peak power up that high you are just slowing down revving way past the power peak.

most cars peak in the 6800 range, the modified cars a bit higher. I think the LPE 390 made best power at 6950 but was only down a few HP at 7200. I have my shift light chipped for 7400 and the rev limiter set at 7600. no point going any higher, power continues to fall off and you are just thrashing the engine. it will take it as curtis pointed out.

with mike's heads and some good cams the power peak will indeed shift upwards and may go as high as 7400, time will tell. but if you have ever looked at the port volume on the lt5 it's actually a bit small for max rpms. they strived for excellent velocity which the LT5 excels. that gives the car the smooth buttery response. at low rpms along with the secondary system.

fastlane did some pretty radical changes to shift the power in the 8500 range. it would take much better flowing heads and intake to do it just as he did.

I'll ask him at BG what his heads flowed at. my bet is pretty close to 360-380 cfm and the custom "tunnel ram" style intake really helped with the power at high rpms.

the factory tuned port setup is more for torq with the long runners but it can be a bit restrictive.

if anyone is interested, the quickest zr-1 on the planet is for sale and on display at the NCM. very interesting car. Lane is no longer interested in racing it, and he also has his "backup" engine which I believe is a 377 making over 700 HP. part of the secret to this is super high compression ratios. the 377 is at 15-1 and I believe the 431 is around 16-1. race gas only on these folks.

Fastlane is truely a pioneer and not afraid to push the envelope (and rip out all the sides!!!)

DDSLT5

Mine is off by 500 rpm at 7000.

8388

This is a fact. Especially with the alt.

DDSLT5

That is why I put underdrive pulleys on the alternator and the power steering pump.

32valves

ttt

SurfnSun

I shifted at 5500rpm once, it was screaming...but making no power.

8388

yeah, but at 4800 rpms

SurfnSun

Thats a whole different ball game