What restricts the LS and B20 from high rpms?

I ask because the r/s ratios of the GSR and ITR engines are 1.58 vs 1.54 for LS/B20 (not that big a difference) and was trying to come up with reasons for the difference in the engines' rpm tolerances because that small difference can't cause the huge disparity in redlines (6800 vs 8100 and 8500).

So far the reasons I've come up with are:

1)Valvetrain
2)Heavier Piston(B20)
3)GSR/ITR has a block girdle(fixed by Z10 girdle)
4)GSR/ITR has stronger rods(but by how much really?)
5)Oil squirters(mainly for sustained high rpm, right?)

I was thinking that shouldn't the LS be able to safely rev to 8000rpm with an upgraded valvetrain and Z10 block girdle, and if so how much of a restriction is the additional weight of the B20 pistons which are on LS rods? Am I missing something?




[Modified by Muglit, 7:34 AM 10/28/2001]

 

Basically what you listed is what it is.

The valvetrain needs to be upgraded, a crank girdle is needed and stronger rods/rod bolts. You can easy rev to 8000-8500 with that setup.

Larry from Endyn says with proper pistons/rods/etc you can easy rev to 9500 with the B20...but I wont take his word for it.

 

9500 should not be a problem with properly balanced internals and the right parts. There are bearing coatings that they use in Legends cars that have raised the rev limit 500 RPMs, something like that will also be good in a B20.
Most people on this board do not rev it that high due to the lack of parts, or their power band. I would think that most on this board have power that peaks lower than a B18C. I am not saying everyone, but your average setup...


Jason

 

cylinder wall side loading also poses a restriction on the B20 and LS engine's when you want to rev high. if it's built up right then 8000-8500 will be OK but will still "wear down" over time.

 

So do you guys think the main restriction is the valvtrain, rods, or lack of girdle for the b20 and LS?

 

My question is along the lines of which valvetrain components? I know the springs for sure, but the valves and retainers as well?

 

What about the valve train? The springs? Is that the only problem?

Wha tthe hell is a girdle?

 

There would be no point in revving higher unless you had more aggressive cams because you won't make any additional power with higher revs with the LS/B20 cams.

So if you get new cams, you'll need new springs to handle the cams and higher revs. As for the valves, I've heard that they are a good idea as well since lighter valves will be easier to actuate at higher rpms. Some lighter retainers are usually suggested as well.

People have suggested that you might not want to go for the strongest valves because if anything happens like piston to valve contact, that you would want a valve that would bend rather than break off and bounce around in the combustion chamber. Stronger valves tend to be more brittle and will break off more easily.

A girdle bolts underneath the crankshaft and stiffens the block so that during high rpms things don't shift around and start breaking. the B18C1 and C5 both have block girdles.