View Poll Results: Which would be a better bang for the buck both built out of a 6.0 iron block?
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info on which to build 370 or 408
info on which to build 370 or 408 I have a buddy that is looking to build a new short block in the near future. He is debateing between building a 370 or a 408. He would like to use his ported ls1 heads he already has. He's looking at probably about $1000 difference between the 408 and the 370. Would it be worth spending the extra $1000 or so to build the 408 if he plans on running his ls1 heads on it? I am guessing maybe a 20 hp difference between the 370 and the 408 what do you guys think?
I am doubting the 408 would make much more power than the 370 with out upgradeing from the ported ls1 heads on it. We would like to get some more input on it though.
I know the 408 with more ci will make more power with better heads but for now the motor will have stock ported 99 ls1 heads on it with 2.02/1.57 vlaves. I will try to add a poll to this also. The car is a street/strip car and which ever he builds will be pump gas friendly.
I am doubting the 408 would make much more power than the 370 with out upgradeing from the ported ls1 heads on it. We would like to get some more input on it though.
I know the 408 with more ci will make more power with better heads but for now the motor will have stock ported 99 ls1 heads on it with 2.02/1.57 vlaves. I will try to add a poll to this also. The car is a street/strip car and which ever he builds will be pump gas friendly.
Last edited by bigfatls6; Dec 31, 2008 at 01:33 AM.
I'm starting to lean towards the 370. How much HP difference is there between the 370 and 408 it both motors has the same heads, cam, intake etc...
I really don't have any intentions into making this car into a drag car so I do not foresee me buying new heads in the future. This is not my daily driver but is do drive it to work quit often and it will see some street action so I want the power to be there when I want to play.
I really don't have any intentions into making this car into a drag car so I do not foresee me buying new heads in the future. This is not my daily driver but is do drive it to work quit often and it will see some street action so I want the power to be there when I want to play.
Go with the 370"-375" (4.03" or 4.06" bore) for now with the heads you have. Later you can get the L92 heads and intake that will flow as much or more than full-tilt LS1 heads and LS6 intake 
. If you need more just turbocharge it. The 408 will make tire destroying torque for big smile fun though if it just an every now and then car. Damn, decisions...decisions.
. If you need more just turbocharge it. The 408 will make tire destroying torque for big smile fun though if it just an every now and then car. Damn, decisions...decisions. Go with the 370"-375" (4.03" or 4.06" bore) for now with the heads you have. Later you can get the L92 heads and intake that will flow as much or more than full-tilt LS1 heads and LS6 intake . If you need more just turbocharge it. The 408 will make tire destroying torque for big smile fun though if it just an every now and then car. Damn, decisions...decisions.
. If you need more just turbocharge it. The 408 will make tire destroying torque for big smile fun though if it just an every now and then car. Damn, decisions...decisions.it made 398 to the wheels with the 5.7 (Stock short block), Stock ported 853 heads, FAST 78 intake, stock ported TB, Auto with 3800 convertor. The Cam is a Texas Speed Torquer V.3 Camshaft - 231/234 .643"/.598" 111 LSA
I had the 6.0 installed 2 months ago and installed a FAST 90/90 last weekend. On the Dyno last night we noticed it had very little oil pressure so I'm going to pull it out and have the short block built.
The shorter crank Engine will like RPM's more, but the bigger cubes will have more power. Depends on what you are building and going for.
I love my 402 with L92 Heads, it has power all the way till 6500 without a problem.
That can be taken a few ways...lol
I love my 402 with L92 Heads, it has power all the way till 6500 without a problem.
That can be taken a few ways...lol
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Yep, that is always the trade off. Bigger cubes make the power lower in the rpm range. The smaller motor will need to rev higher to make the same horsepower. I would think the smaller motor would have a slight edge in gas mileage. Decisions, decisions.
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, I don't think this car has the chance to get anywhere near that feeling... 
408.....
The torque is worth the difference. With only stage II PRC heads and a 603/610 lift cam we trapped over 102 in the 1/8.
We could easily pick up a lot with better heads, but with how the car runs if we wanted more I would throw a 150 shot on it...
The torque is worth the difference. With only stage II PRC heads and a 603/610 lift cam we trapped over 102 in the 1/8.
We could easily pick up a lot with better heads, but with how the car runs if we wanted more I would throw a 150 shot on it...
I really don't want to change the heads, I don't want to have 20k in a car and it only be worth 13-14k.
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370.... the stock crank is good for 900hp.
I would only go with a 408 if forced induction was in the mix.
For a N/A motor go with the 370. For the same reason ford guys build 331's over 347's or 408's over 427's. The bigger bore and shorter stroke will rev lighting fast, pop the throttle and it’s rapping 6000 instantly. Same reason GM only went bigger on the bore in the LS2 from the LS1 with the short stroke.
I would only go with a 408 if forced induction was in the mix.
For a N/A motor go with the 370. For the same reason ford guys build 331's over 347's or 408's over 427's. The bigger bore and shorter stroke will rev lighting fast, pop the throttle and it’s rapping 6000 instantly. Same reason GM only went bigger on the bore in the LS2 from the LS1 with the short stroke.
What kind of HP difference is it between the 307 and 408 with the same parts?
If it is a sugginificant amount of difference then I will go with the 408 since it is a little bit more money but I do not want to spend 2k on heads.
370.... the stock crank is good for 900hp.
I would only go with a 408 if forced induction was in the mix.
For a N/A motor go with the 370. For the same reason ford guys build 331's over 347's or 408's over 427's. The bigger bore and shorter stroke will rev lighting fast, pop the throttle and it’s rapping 6000 instantly. Same reason GM only went bigger on the bore in the LS2 from the LS1 with the short stroke.
I would only go with a 408 if forced induction was in the mix.
For a N/A motor go with the 370. For the same reason ford guys build 331's over 347's or 408's over 427's. The bigger bore and shorter stroke will rev lighting fast, pop the throttle and it’s rapping 6000 instantly. Same reason GM only went bigger on the bore in the LS2 from the LS1 with the short stroke.
wait a minute...how much did that big block cost you? and how much was the car worth? it looks like you want the 370 anyway...and no doubt you could get alot more for the 408 than you could for a 370...