Over-square build with space constraints
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Over-square build with space constraints I have experience doing swaps and builds but I'm new to the LS world. I'm starting to save for an LS build to swap my ND miata with the Flyin' Miata kit. I'd like to do an over-square high-rpm build because it will be a road race car and I'm limited to around 245 tires. The hood clearance is tight so they recommend staying with the stock intake manifold and throttle body from the LS3.
Which block design is the best starting point for this type of motor? The LS7 block looks like it has a bigger bore by default, will the 3.267-inch stroke 4.8L crank fit that block? I realize I will need to source pistons and rods. If I'm limited by the stock intake manifold and throttle body, is it better to just destroke the LS3 with the 4.8L crank because I'll be airflow limited? Any advice on this type of build would be appreciated, as the articles etc. out there on destroke builds are rarer.
Which block design is the best starting point for this type of motor? The LS7 block looks like it has a bigger bore by default, will the 3.267-inch stroke 4.8L crank fit that block? I realize I will need to source pistons and rods. If I'm limited by the stock intake manifold and throttle body, is it better to just destroke the LS3 with the 4.8L crank because I'll be airflow limited? Any advice on this type of build would be appreciated, as the articles etc. out there on destroke builds are rarer.
Last edited by ImSteevin; Jul 30, 2019 at 09:11 AM.
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The fascination with over-square builds here isn't really warranted.
The RPM capability isn't limited by piston speed. Its almost always oiling/valvetrain.
Gen 4 4.8 crank and rods will drop directly into an LS3 using LS3 pistons.
The RPM capability isn't limited by piston speed. Its almost always oiling/valvetrain.
Gen 4 4.8 crank and rods will drop directly into an LS3 using LS3 pistons.
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I didn't know there was a fascination with those types of builds, I just thought it's right for this use case and the shorter stroke gives me more oil pan options with the tight space for steering rack and subframe.
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There aren't any oil pans designed specifically for a shorter stroke.
There isn't much you can do in the way of windage trays for the shorter stroke, either, so there isn't a lot to be saved there.
There isn't much you can do in the way of windage trays for the shorter stroke, either, so there isn't a lot to be saved there.
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You're talking about 4" and longer stroke, and the issues associated with the LS7.
Don't use an LS7. Seems to solve 99% of your problems. Every single oiling component, both OEM and aftermarket, is the same for the 3.267" stroke 4.8 and 3.622" stroke 5.3/5.7/6.0/6.2
Don't use an LS7. Seems to solve 99% of your problems. Every single oiling component, both OEM and aftermarket, is the same for the 3.267" stroke 4.8 and 3.622" stroke 5.3/5.7/6.0/6.2
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I think long rodded, short stroked big bores are cool, but I consider it a maximum-effort, rules-specific approach. For a road race application, I would think durability and reliability would be your primary goals, because ANY LSx is going to give you an amazing power to weight ratio in that chassis.
For maximum durability and reliability, I'd keep it simple, and keep the engine speed DOWN, not UP! Every 1000rpm more engine speed makes it 10x harder to get the whole setup *just right* so that it lives a long happy life. 6000-6500rpm is easy and doesn't break.
For maximum durability and reliability, I'd keep it simple, and keep the engine speed DOWN, not UP! Every 1000rpm more engine speed makes it 10x harder to get the whole setup *just right* so that it lives a long happy life. 6000-6500rpm is easy and doesn't break.
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I mean like 7k, I'm not just trying to hit some magic number I mostly want to shift the power band to the high end so the power delivery is better for corner exit. If there's a different way to do that it might be easier. My understanding was this is the type of build to do for this application, especially when I can't just solve traction problems with more tire.
I mean like 7k, I'm not just trying to hit some magic number I mostly want to shift the power band to the high end so the power delivery is better for corner exit. If there's a different way to do that it might be easier. My understanding was this is the type of build to do for this application, especially when I can't just solve traction problems with more tire.
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I'd just do 3.08 rear end gear with a ls3 crank. 500 hp @ 6700 easy. Light car that rolls, car would have no top end it would seem... Needs more hp for higher Speeds. Killed the launching and tire spin with the lower rear end gear choice. Driver to car lesson# 51. Lol.
You can control traction and power with timing, don't turn the car into a turd by messing up the gearing. He can knock power out of the tune as needed very easily.
On The Tree
Joined: Jun 2019
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From: HTown, Texas
I have experience doing swaps and builds but I'm new to the LS world. I'm starting to save for an LS build to swap my ND miata with the Flyin' Miata kit. I'd like to do an over-square high-rpm build because it will be a road race car and I'm limited to around 245 tires. The hood clearance is tight so they recommend staying with the stock intake manifold and throttle body from the LS3.
Which block design is the best starting point for this type of motor? The LS7 block looks like it has a bigger bore by default, will the 3.267-inch stroke 4.8L crank fit that block? I realize I will need to source pistons and rods. If I'm limited by the stock intake manifold and throttle body, is it better to just destroke the LS3 with the 4.8L crank because I'll be airflow limited? Any advice on this type of build would be appreciated, as the articles etc. out there on destroke builds are rarer.
Which block design is the best starting point for this type of motor? The LS7 block looks like it has a bigger bore by default, will the 3.267-inch stroke 4.8L crank fit that block? I realize I will need to source pistons and rods. If I'm limited by the stock intake manifold and throttle body, is it better to just destroke the LS3 with the 4.8L crank because I'll be airflow limited? Any advice on this type of build would be appreciated, as the articles etc. out there on destroke builds are rarer.
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I don't think one person here cares about getting 300k miles out of an engine, but even then 200k+ mile truck engines get spun to 7500+ with a bunch of boost on them, they still hold up for years.
Originally Posted by JoeNova
I thought you were talking like 8k+ lol.
Find a stock L76, L99, LS3. There won't be a considerable amount of work needed to get over 500 horsepower and 7k is fine for them.
Find a stock L76, L99, LS3. There won't be a considerable amount of work needed to get over 500 horsepower and 7k is fine for them.