400ci
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Launching!
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From: wi
400ci Anybody build a stock stroke 4.185 bore motor for street/strip duty? This looks like it would be a great street motor and be very fast with some now proper built. Thinking about doin one of these with a resleeve alum 5.3 block, exhaust ported only l92 heads and a radical ported l92 intake 11.5 compression in an auto.opinions anyone? Thinkin maybe a 200 shot also.
Anybody build a stock stroke 4.185 bore motor for street/strip duty?
Only reason I see for staying with a short stroke is for high revving road track motors. A street/strip car is not one that really needs to see 8000rpm for extended periods of time, so you'd want as much stroke as possible for more torque under the curve which is great for a street car and one that needs to accelerate quick.
For a purely top end screaming engine yes your setup would be great.
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Launching!
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From: wi
If a 4.065 bore and 3.62 stroke motor works well with the ls3 cyl head, y would a 4.185 bore not? It should produce more power than the 4.065 bore motor, Properly cammed and have a very broad curve also. Valves are Unshrouded,good compression should make for snappy street motor. I'm only increasing the bore to get displacement. I don't understand y this wouldn't make a doable street motor. With today ls cyl head tech and cam gurus out there this would be easily a rockin street motor.
TECH Fanatic
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From: Marengo, Ia
Valvetrain stability is the real problem with building a 8000rpm motor, not bottom end strength. It would likely be cheaper and easier to build a 440 that only spins to 7000rpm, has better torque curve, and would make the same if not more power.
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For the cost spent, you won't see much benefit over just a stroker LS2. The added bore opens up more head options, but most of them need more CID than you'd be giving them.
I'd also use LS7 heads on something with that much bore.
Preferably, I'd do a 4.185" bore with 4.125" stroke and spin the 454 to 7500 all day with some aftermarket LS7 heads and aim for 700rwhp all motor.
I'd also use LS7 heads on something with that much bore.
Preferably, I'd do a 4.185" bore with 4.125" stroke and spin the 454 to 7500 all day with some aftermarket LS7 heads and aim for 700rwhp all motor.
If a 4.065 bore and 3.62 stroke motor works well with the ls3 cyl head, y would a 4.185 bore not? It should produce more power than the 4.065 bore motor, Properly cammed and have a very broad curve also.
And like Jake said, that much bore will allow for some nice heads but will be dragged down by the overall smallish displacement. What's the point of a 450+ cfm flowing head with 2.200" intake valves when all it has to do is feed a measily 400 cubic inches?
Get a 4+ stroke in there and you'll still be able to rev to 7200rpm but have a much meatier torque curve before that. Stock stroke on such a beastly motor is mainly for those limited to a certain displacement size.
Approximately sixty percent of an engine's rotating friction is the piston rings. Racers have been thinning them down for years and even the manufacturers have gone this route to help fuel mileage. Less BSFC if you will.
Let's make a few calculations at the OP's intended 7200 rpms, or 120 revolutions/sec.
All 8 pistons travel 289.76 linear feet of distance each second in a 3.622" stroke combo.
@ 4.000" that distance jumps to 320 feet/sec.
4.125 equals 330
I'm thinking the OP's combo would make less peak but more average torque than a 4" X4"
engine (all other parts being equal). Smaller NA motors for lb/in classes always seem to
make less overall power but are more efficient because of the breath ability and reduced
piston speed.
This helps to explain why NASCAR engines (4.185 X 3.25) survive @ 9000 plus rpms as
the piston speed is similar to a 3.75" @ 7800 or 4" @ 7300.
A set of floor epoxied (smaller CSA) Frankenstein LS7 heads would be badass on this OP
combo, however the Ex. ported LS3 heads is still a pretty darn good idea if the right bump
stick is used.
Let's make a few calculations at the OP's intended 7200 rpms, or 120 revolutions/sec.
All 8 pistons travel 289.76 linear feet of distance each second in a 3.622" stroke combo.
@ 4.000" that distance jumps to 320 feet/sec.
4.125 equals 330
I'm thinking the OP's combo would make less peak but more average torque than a 4" X4"
engine (all other parts being equal). Smaller NA motors for lb/in classes always seem to
make less overall power but are more efficient because of the breath ability and reduced
piston speed.
This helps to explain why NASCAR engines (4.185 X 3.25) survive @ 9000 plus rpms as
the piston speed is similar to a 3.75" @ 7800 or 4" @ 7300.
A set of floor epoxied (smaller CSA) Frankenstein LS7 heads would be badass on this OP
combo, however the Ex. ported LS3 heads is still a pretty darn good idea if the right bump
stick is used.
Thread Starter
Launching!
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From: wi
So for shxx n giggles what kind of ballpark came selection would a motor like this run on the street? In the lil simple engine dyno program I have I spec a 229/237 @.050 with a 114114 lsa with a 112 icl. .630/.604. At 20% driveline loss, still makes about 380lbs of torque from 2500 up and carrys the power to about 7100 with about 30 lbs more in most places on the graph. The real down side I see here is long block cost and not able to use large power adder.
TECH Fanatic
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From: Marengo, Ia
If the high short block cost causes you to be limited to LS3 heads with only the exhaust ported then you'd probably be better off with a LS3 based 416 and much better heads. The longer stroke would build more low end torque and the better heads would make more top end power.
Thread Starter
Launching!
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From: wi
Here is a better question y won't this combo properly cammed not be as snappy as a smaller bore short stroke combo? Everybody talks about road racing type of combo this is. And for road racing u need broad torque curve. Same as street. Y won't it work.
Thread Starter
Launching!
Joined: Mar 2011
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From: wi
Here is a better question y won't this combo properly cammed not be as snappy as a smaller bore short stroke combo? Everybody talks about road racing type of combo this is. And for road racing u need broad torque curve. Same as street. Y won't it work.
Here is a better question y won't this combo properly cammed not be as snappy as a smaller bore short stroke combo?
But as said before, a different setup with a longer stroke and even smaller bore will make more torque and power. A proper setup 416 will kill it in torque and snappiness and make more power up top to boot.
Thread Starter
Launching!
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From: wi
Hot rod tested a pair of stock ls3 heads on a 468 stroker and made something like 690 horses. Stock heads. Clean up the exhaust ports and run about 11.5 compression and cam correctly for the street should make more that a ls3/l92 combo. If a 468 can make that power at 6900 rpms then a properly cammed and headed 400 with a 4.185 bore should be a blast. I'm only adding bore over an ls3 combo. I have plenty of opinions but no real answer.lookin for the y and y not.