devilfish

Is the lt1 bottom end better then the l98? The lt1 intake create power at 6000rpm, so GM should make them "better" then the old tpi that goes out of breath at 4700rom or?? What is the diffrense

0ski_dwn_it

Not real sure about exact differences, but I am sure the reason the LT1 are better at higher RPM are the intakes and heads. Not the lower 1/2. Also the L98 are every bit capable of spinning 6000 RPM, if the air is there.

scorp508

I'm pretty sure....

L98 = 2-bolt block
LT1 = 4-bolt block

As for the rotating assembly itself I'm not too sure. L98 will spin 6000+ like ski said. I wouldn't spend much time over 6300 though, you've gone past the critical piston feet/minute of cast piston. They would probably be ok, but I don't want to risk it. If you are just passing it and shifting thats one thing, but don't hold it there.

gtsyellow

it's normally the milage and age that kills the L98s, the bearing clearances get big and the engine vibrates in the high rpms. the rings get brittle from age and fracture. a cast piston can handle some rpms and power if it's set up correctly, they just melt when you detonate. if someone tore down a L98 and balanced it, set the bearings up right and used better rings they would live at 6500rpm all day long.

the 2 bolt bottom end can be reinforced with APR main studs which allow more pressure to be set on the main cap and also don't stretch or flex as much as a bolt does. the engine in my sig was built on the factory 1990 2 bolt block since i couldn't find a 4bolt in time. the biggest difference is just clamping force on the mains. the 4 bolts have more area to clamp down on & that's definatly to your benifit in high rpms, it's less likely to walk.

vader86

An L98 bottom could hold out just as well if built correctly. From the factory though, id say that the LT1's might be a bit tougher.

Remember the only real engine characteristics are in the cam, heads, and intake. If the L98 had a similar intake and cam, theres no reason it wouldnt be able to run side by side with an LT1.

Storz

Is there really a point to taking an L98 up to those high RPM, its pretty much done making any power by at the most 5k.

gtsyellow

yep, it's the manifold, the #1 reason a LT1 cranks higher is the better manifold design.

scorp508

Stock, not at all. With a stock L98 you should be shifting no later than 4400-4600 RPM to maximize your overall torque/hp. But... when you add an aftermarket manifold like the superram on my car you're suddently shifitng another 1500 RPM higher because the thing can finally breathe.

18carfan

The crankshaft, rods, and pistons are interchangeable between an LT1 and an L98. Some small production changes were made at various times but it seems that the late L98's and early LT1's used the same rotating assembly except for the pistons possibly. -Jeff

LPDesRoche

The LT1 rods a fair amount stronger than the L98 rods. They made a few rod changes over the years, not specifically in design but in weight and casting process. The L98 rods were inherently weak for quite a while. I do know that was corrected for the LT1's. Thats not to say that when looking for a replacement from the factory they won't all carry the same part number now,because they are interchangable. Then again most people are not going to make the kind of power that is going to be bending rods anyways. More than likely you will end up with rod bolt stretch will can be eliminated by installing a set of ARP bolts anyway.