I'm curious to know what people are spinning their 4" stroke motors too. Obviously higher means more piston velocity, but what is the upper limits of "safe"?? I am debating on going solid roller and turning it up a bit, but want to see what others are doing first.

If you're spinning above 6,500, what intake is on it and do you mind sharing cam specs.

I am currently spinning mine to about 7k
Hyd 245/260 .646/.629 106/109lsa
Super Vic with a 4150 to 4500 adapter and a dominator TB.

Here is a graph, peaking at 6,750. The lower HP graph is my old 347 Trex combo but everything else the same.

 

Not that I recommend it on a daily basis, but we've spun 7500 with a 4.125" stroke, fast intake and 249* with a 109ICL

 

7200 with a ported fast 90 and a 238/240 on 112

 

Up to 9500+ and 4.250" stroke. Usually a sheet metal intake, CCW crank, and 260-280 duration cams at that level. You will definitely be more limited by the valve train than the bottom end...

 

Uuumm..... dyno vid please

 

It would all dictate on the quality of parts used and the oiling system. I've seen people lose engines at 6000rpms and 8800rpms.

 

7200 rpms, though I have spun it up to 7400 on occasion. I run a ported FAST 90mm.

 

So 7,500-7,800 is not out of the question. The AFR heads I have have light weight intake valves. I don't mind switching springs if needed, and this is not a daily driver motor.

 

Upto around 7400rpm, i am on Kinsler ITB's, at that rpm the engine seems to change note and go flat, i think that valve float has set in then, i am running Dual Gold springs.

Cam in sig.

 

I run the AFR 225 with lightweight valves and the 8019 spring. I do worry about the oil not draining back fast enough at that rpm, so I always run 7 quarts of oil, which helps but it's something to consider.

 

Hey Jon, was that with an Ultra Billet?

 

I'm planning on 7500-7700 with my build. Restricted pushrods are an option if it's a race only deal to keep more oil in the bottom. I'm not going to do restricted pushrods since mine is going to be a daily driver. I'm going to chop up my oil pan to increase capacity.

 

GM redlines the 4 in stroke ls7 at 7k with wimpy single valve springs.

 

My 414 turns 8500. GMPP single plane and scorpion throttle body. 255/265 .700 110 lsa

 

I have run mine 6800-6900. I think the valvetrain is the limit. I spun my stock bottom end to 7200 with a ton of nitrous passes. Good lightweight valvetrain.

I have Heavy l92 valves I woluld not feel safe over 7k.

 

I'll be spinning my build in my sig to around 7800. It's a 4.100" storke. I bet my cam and heads will pull till around 8500... But do not thing bottom end and oiling system will like it or even hold it.

 

solid or hyd roller?

 

His is solid.

 

7500-7700 rpm is a lot to ask of a daily driver. Same for thoughts of solid roller - great stuff just not what you want to try to drive every day. Cam timing to get power at this level won't be much fun to drive every day.

I'll be first to admit I know nothing of solid rollers in LS engines. I know many who have tried solid rollers on street driven BBC's - most don't last too long and when they go, bad things happen.

Just curious how much power you are looking to make.

 

6600-7000 with the limiter set at 7200. Hyd roller, with a L76 intake. Intake limited but has a nasty mid range. street driven