370 vs. 408...which one and why?
04-29-2008, 09:17 AM
#43
550 is only the goal.
Right now I have a stock 30k mile LS1 that I do not want to have forged internals put in. It doesnt make sense. And building a forged 347 is going to cost more than a 370. The only thing I'm really giving up is the aluminum block...
LQ9 heads for sure.
Right now I have a stock 30k mile LS1 that I do not want to have forged internals put in. It doesnt make sense. And building a forged 347 is going to cost more than a 370. The only thing I'm really giving up is the aluminum block...
LQ9 heads for sure.
05-01-2008, 12:17 AM
#44
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Big Bore/Short Stoke Turbo/Centrifigal It depends on your usage. Is it mostly street with some strip or the other way around. Mostly street I would go 408 more torque and ability to spool quicker makes it more streetable. Powerband would be sooner and no doubt create big issues on power managment on the street. This is with a 76 or larger turbo.
Mostly strip and racing very little street time. Go short stroke and big bore. Turbo's love RPM because they make power off exhaust gas velocity and as long as you have no restrictions on the exhaust side especially it will just keep pushing you in the back as far as the engine can keep spinning.
I have had no experience with centrificals, but own 5 turbo cars and I have been told by the engine builder big bore and short stroke is a good combo. Also you have to consider rod angle and piston to rod angle same thing. The shorter the stroke the better the rod angle; less side load; less friction; more horsepower and greater engine life.
Good luck!!!!!
Mostly strip and racing very little street time. Go short stroke and big bore. Turbo's love RPM because they make power off exhaust gas velocity and as long as you have no restrictions on the exhaust side especially it will just keep pushing you in the back as far as the engine can keep spinning.
I have had no experience with centrificals, but own 5 turbo cars and I have been told by the engine builder big bore and short stroke is a good combo. Also you have to consider rod angle and piston to rod angle same thing. The shorter the stroke the better the rod angle; less side load; less friction; more horsepower and greater engine life.
Good luck!!!!!
05-01-2008, 01:19 AM
#45
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It depends on your usage. Is it mostly street with some strip or the other way around. Mostly street I would go 408 more torque and ability to spool quicker makes it more streetable. Powerband would be sooner and no doubt create big issues on power managment on the street. This is with a 76 or larger turbo.
Mostly strip and racing very little street time. Go short stroke and big bore. Turbo's love RPM because they make power off exhaust gas velocity and as long as you have no restrictions on the exhaust side especially it will just keep pushing you in the back as far as the engine can keep spinning.
I have had no experience with centrificals, but own 5 turbo cars and I have been told by the engine builder big bore and short stroke is a good combo. Also you have to consider rod angle and piston to rod angle same thing. The shorter the stroke the better the rod angle; less side load; less friction; more horsepower and greater engine life.
Good luck!!!!!
Mostly strip and racing very little street time. Go short stroke and big bore. Turbo's love RPM because they make power off exhaust gas velocity and as long as you have no restrictions on the exhaust side especially it will just keep pushing you in the back as far as the engine can keep spinning.
I have had no experience with centrificals, but own 5 turbo cars and I have been told by the engine builder big bore and short stroke is a good combo. Also you have to consider rod angle and piston to rod angle same thing. The shorter the stroke the better the rod angle; less side load; less friction; more horsepower and greater engine life.
Good luck!!!!!
05-01-2008, 03:09 AM
#46
If you had a turbo setup I would go 370, with a factory crank, but for what you are wanting to do the 408 might be the way to go. It's allways a good idea to have a forged crank with a supercharger, due to the extra load on the snout driving the blower. On a side note a 6.0-370 can make power down low in the rpm if the combination is right. My 4900LB 4x4 truck runs mid 10's hear in Co at over 5000' elevation, with a mild 6.0L shifting at 52-5400RPM. That's easy mid to low 9's in a FBODY at low elevation.
05-01-2008, 10:22 AM
#48
only reason i can think of to increase cubes is if you are octane limited and have no work around.
why have a radical gaz guzzling 600hp engine and put 400 of boost on it when you can have a nice calm streetable 400hp engine with 600 of boost on it.
1000 total either way, parts take the same beating
why have a radical gaz guzzling 600hp engine and put 400 of boost on it when you can have a nice calm streetable 400hp engine with 600 of boost on it.
1000 total either way, parts take the same beating
05-01-2008, 01:55 PM
#51
Good choice! With the LQ9 heads, a decent blower cam, and 7-8 PSI you will be over 500 rwhp. I would say though that you should get a meth kit just for safety sake if you want to ensure that the stock shortblock last a while. A spot on tune and meth work wonders! Good luck with the build!
05-01-2008, 07:42 PM
#52
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If you had a turbo setup I would go 370, with a factory crank, but for what you are wanting to do the 408 might be the way to go. It's allways a good idea to have a forged crank with a supercharger, due to the extra load on the snout driving the blower. On a side note a 6.0-370 can make power down low in the rpm if the combination is right. My 4900LB 4x4 truck runs mid 10's hear in Co at over 5000' elevation, with a mild 6.0L shifting at 52-5400RPM. That's easy mid to low 9's in a FBODY at low elevation.
05-01-2008, 11:22 PM
#56
Alot of the same rules apply. Either way you go the combination needs to be able to work as a whole. You need to be able to keep your ci's fed, blower or turbo. Given the choice I would opt for the forged crankshaft if I was running a supercharger, and if your going to spend the $$$$ on a forged crank you might as well go with the 408.
05-02-2008, 05:15 AM
#58
The blower puts alot of extra stress on the snout of the crankshaft. Im sure for the power level you are after you would be fine with a stock crank. As for the CI's at that power level that supercharger you have should feed either engine, but the 408 will run better pree boost. Now if you were after 700RWHP I would go with the 370. Last edited by stock48; 05-02-2008 at 05:24 AM.
05-02-2008, 05:35 AM
#59
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05-02-2008, 09:59 AM
#60
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Great thread with lots of info/opinions. I went iron 402 on my build, reason? I should be able to make the same power as the stock stroke but with lower boost=less head sealing issue.. just my 02.