I've been looking over the threads, sorting through the usual "how do u get more faster with no money lulz" and so on.. You might lump me into that category, but we'll see.

Here's what's been running through my head. Are LS3 engines built to rev higher like the GM 302's or short the track 377's? I assume they're a short stroke motor that compensates with displacement to make torque. A 383 stroker just seems like a frankenmotor that will beat itself to death, and won't run reliably more than 50K miles.

I want an engine that's streetable, runs A/C, doesn't overheat in traffic, and winds up like a banshee in heat, IF I choose to do so. (Which probably won't be all that often, since high revs kill motors) I really want a road track motor, with a moderate cam.

I've thought about buying an older iron-block pontiac 400, short-stroking it down to 377, putting aftermarket FI on top, and seeing if I could get AI to work up a set of heads for it. This brings up gauge issues, fit issues, but I think I could do it for less than what I'd spend for other options. Overheating was an issue for the mouse motors, but they could be screamers. Forged crank? Probably, since I don't know what they use to shorten the stroke. Stock cranks would hold up, but again, I'm not sure how they get the stroke down to a 377.

The LT/LS motors make sick power, but new LS3's cost more than I have.
Any thoughts?

 

Umm.. not even sure what you're asking, but the LS1, LS2, and LS3 all have the same-sized stroke at 3.62".

The bore size is what changes the displacement from 5.7L to 6.0L to 6.2L.

Why would you want to destroke a motor like that? The only reason IMO to destroke a motor is if the motor is already undersquared like some of the old Oldsmobile, Buick, and Pontiac motors and you're trying to make it oversquared.

Your best bet is picking up a junkyard LQ4/LQ9 block that's already 4.0" bore, boring it .030" over and throwing a 4.00" stroker crank with some decent pistons/rods, some good heads/intake/cam in it and making 500 rwhp on motor.

Mike

 

Well, that answers some of my questions, but I'm new at doing the motor thing. I had heard that the dirt track guys would take a 400 and shorten the stroke, the net effect being a motor of reasonable displacement that could be wound up to higher rpms. I've never driven a GM 302 that was in the 1st gen Z28's but- I've heard one, and seen it go screaming down the road- I fell in love with that sound. The only drawback of that old GM 302 was a lack of torque.

That's why I'm so fixated on the idea of a 400 de-stroked. It should have more torque due to it's size, and as a bonus, a high RPM band. This should move a 33-3500 pound car along pretty well, and I -think- I could get 450 hp without tweaking the motor within an inch of its life. A 2:73 rear or a close approximation should also give me streetability and a monster top end.

 

High RPMs don't have everything to do with cubes... it has much more to do with the size of the cam and how the heads flow -- Extremely high RPMs are stupid anyway --- You'd need much more exotic valvetrain, oiling, and to produce what?? The same horsepower and lose a ton of bottom-end and streetability?

I think you're missing the point

 

I'm not talking about a twin cam, 14000 rpm motor.. The old chevy gassers would take a 327, drop in a 283 crank, and have a home made 302 that they would wind up to ten grand and drop the hammer off the line.. The Penske Camaros of the 60's had factory 302's with 202 vette heads that were state of the art at that time, by doing the same thing- Same principle. With higher flowing heads and bigger displacement, I could make up some of the loss of torque at the bottom end- I think.
A 383 is a torque monster- Is that due to the length of stroke, or displacement? If I'm thinking right, a longer stroke equals more torque, so to strike a balance, I'd try to make up for the loss of torque by using a bigger C.I block to start with.

 

You got to get out of that old-style thinking with the Gen III/IV motors. If you only want 450 horsepower, stick an aftermarket cam and some longtube headers into an otherwise stock 346ci LS1 motor. Wha-la. No big deal. The LS1 comes with a full roller motor (including 1.7:1 rockers), 15* intake valve angle aluminum heads, an aluminum 6-bolt block, and a composite intake manifold with a serious crank that is good for 800+ horsepower and rods that are good for over 650 horsepower. There's honestly no reason to "build" a Gen III/IV motor for a "measly" 450 horsepower.

That old **** didn't make power because the heads/intake manifold sucked (or didn't suck enough. haha), cam selection/development was nil in those days, and the fuel delivery and ignition components were crap. Tuning those motors was a joke.

Today's technology completely buries the technology of the Gen I and even Gen II SBCs.

Unless you have any questions specific to the LSx platform, I can move this thread into a different forum if you'd like

Mike

 

No- No need to move the thread at the moment, and thanks for indulging me while I brainstorm..
I want to make sound decisions on the money I spend. In a perfect world, where I had more money at my disposal, I would stuff a turbo (or two) in there- High end powerband problem solved.
Ideally, I'd like a motor that I could take into a corner in third gear, have enough torque to pull me out, and wind it up to 8500- 9000 before I hit the next gear.

Cam and head choices on an LS1 or even an LT1 would be really the way to go then. I was in love with the idea of a shorter stroke because of the smoothness in the RPM range. You do that to a 383, and any weaknesses in the motor will be exposed.

 

Once again:

You aren't going to make that kind of RPM with a SBC of any type unless you put some seriously high $$$$ into the motor --- however, you theoretically COULD do it but WHY? You can make 650+ horsepower on pump gas @ 7000 rpm with a built Gen III/IV-based platform.


What's with the 383 hate? Apparently you're hearing this information second-hand or from someone who doesn't know what they are doing or from some ****** on the internet. A typical SBC 383 is a 4.030" x 3.75" motor -- a .030" over 350 block with a bigger crank. Looking at that setup, since the motor is still largely oversquared, life of the motor isn't an issue at all -- I really don't know who's feeding you this stuff You're looking to make 8500-9000 RPM and you're worried about motor longevity? Come on, dude.

 

I hear you.

I know just enough to be dangerous. This is most of my problem.. I have a "magic motor" setup in my head that does this, does that, doesn't do this, yadda yadda. I've never built one, had one built, so this is at the heart of the problem. Inexperience, and just a teeny bit of knowlege.

 

I figured that out from your first post

 

Ouch.