hey guys
did all the l98s come with cast cranks? what the highest rpm that you have spun? what do you think it will safely spin with a balanced stock shortblock. this is not taking into concideration for intake limitations, just shortblock.
thanks

 

Well....

Im fairly sure all L98 ( as well as most other SBC) came with Factory Cast Cranks, but Don't quote me on that.

As far as Max tolerable RPM, with Stock Rods, Crank... Good bearings and Good attention paid to detail, I would think 7k Could be within semi-safe reach.

But I don't know. Have to defer to someone withh a bit more knowledge of the subject here


It also depends a bit on how much power you are making up There, as that adds to strain.

Don't Forget a Good quality Balancer

 

If your talking about a 2 bolt main L98 I wouldn't take it over 6000 rpm...yeah a 4 bolt main would do 7000 rpm but if you don't want the whole bottom end falling out of your motor if it is a 2 bolt, don't go over 6000rpm

 

I don't think thats entire true.

Being 2 bolt or 4 bolt has less to do with survivability at high RPM than Quality of parts and assembly does.

Unless you are planning some rediculous build, I think a 2 bolt will suit the needs just fine.

 

a 2 bolt isn't that bad, I've had my 305 over 7000rpm before. I"m sure that was pushing it, but I mean I take my 305 to 5500 ALOT. my trans am is my dialy driver so I hardly ever take it over four thousand RPM

 

The max RPM for a 305 TPI is 6000. I would only take a 350 TPI to around 5800 Max unless u wanna wreak ur ****.

 

I hit around 6,800 with mine due to a bad downshift (damn automatics!)

Ever since then, I have a ticking noise in the motor in unison with the rpms. It's not down on power, but the noise is a little unnerving.

 

ummmm i get nervious around 6000...plus there is not point to go that far on a TPI motor....i shift around 5200......

 

If you wanna spin some rev's with a 2 bolt, make sure you use high quality cap stud's instead of the stock bolts, and you sure won't wanna do it for extended use. A good balance job, good attention to clearances, and you'll be ok for some trips down the strip (as long as your not making insane amounts of power) at up to 6500, wouldn't go much higher than that. You start putting out 450-500 hp or more, I'd definitely go with a 4 bolt, and a nodular crank.

 

I've watched a stock shortblock spin 7k rpms in traxion's car. Would i or he recommend it long term, of course not, but if the engine is in good shape, it will take it.

 

Here's a question for you guys....
I'm running my TPI on a goodwrench crate motor w/....Nodular Iron cast crank, hypereutic pistons, and LT1/LT4 powdered meatl conecting rods...says it's the same bottom end components as the production LT1 in the Camaro and Corvettes......so do you think I can go any higher than a stock L98? I'm not sure what the LT1s rev too, but I think it's a little higher?

 

GM designed the 2 bolt to be safe with 375hp@5750, 6000 in practical use. The stock valve train gets very inaccurate (valve float) above 6200.

 

My car sees 6600 rpms religiously. The motor has never been out of the car and the pan has never been removed. An L98 with an updated valvetrain can handle the abuse. Not sure how long it will handle it - but it will handle it. I know others who have done the same. I would definitely recommend a good harmonic balancer if you plan on doing this religiously like me. I'm running a fluidampr.

... and, as Ed said ... sometimes my motor goes even higher than 6600

L98 bottom ends are A LOT stronger than people give them credit for.

Tim

 

as someone else said
there is no point to go above 6000 with a tpi setup
if you have a miniram or superram reving to 7000 may be worthit but in reality if you have a stock 305 or 350 you should shift it at 5200 any hight and you will actualy start slowing down
i have trake tested this
with my 305 i went down the track shifting at 5500 every gear and then i went down it again and shifted at 5200 and got better times when i shifted lower
i have brought my car to 6200 but not on purpose
for some reason one day i was hiting it on an open road and when i hit 3rd i let off the gas and when i floored it again it shifted into first and reved like it was in neutral
scary $hit