Convince me to go 347 or 383
11-07-2015, 12:09 PM
#1
Convince me to go 347 or 383 Looking to build a motor for my mustang, I had a spare block sitting out in the garage with a scratch in number 7, I emailed Steve at RED and he informed me for $500 he could sleeve it and machine it and send it back good as new. My question being, what size should I go for the motor? It's going to be a daily driver so about 5-6 thousand miles a year. For heads I have TEA stage 1 LS6's (can also send them back for 2.5 program for like $350). Thompson also has a forged LS2 for like $3600 with a warranty as well, how much more would a stroker run versus one of their motors?
11-07-2015, 12:27 PM
#3
Yeah I saw that, perked up my ears when I was reading. I have an LS1 crank but I have no idea the condition it's in as it's still in the block. I know the cost wise thing would to just buy a set of forged rods and some diamond Pistons or mahle drop ins. I was also thinking iron block, but I could see myself buying an IRS for $1100 and having an even better car.
11-07-2015, 12:45 PM
#4
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A decent stroker kit (crank/rods/rings/pistons) is around $2,300 plus machine work on your block. I went that route but you may want to consider the LS2. With better heads and cam that will put down big power. I didn't want the bother of computers, wiring, etc. when after stroking I could just drop it back in and tune it.
11-07-2015, 01:28 PM
#5
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I build a forged bottom end 347ci Ls1, now planning to build bigger ci engine want more power and performance. If you can afford larger displacement build I'd do it from the beginning
11-07-2015, 10:28 PM
#6
Yeah I saw that, perked up my ears when I was reading. I have an LS1 crank but I have no idea the condition it's in as it's still in the block. I know the cost wise thing would to just buy a set of forged rods and some diamond Pistons or mahle drop ins. I was also thinking iron block, but I could see myself buying an IRS for $1100 and having an even better car.
Aaron@ThompsonMotorsports.net
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11-07-2015, 10:38 PM
#7
I was going to go the 347 route (I'm turbo though) but decided after talking to John At ljms I'm going to 3.8 bore on my 5.3 block for the extra thickness for more boost. I even bought a set of 3.903 diamond Pistons I was going to use in it for the extra ci but I'm going to let the turbo do the work. with it being a DD I personally would go 347 for the simplicity of it and cost and still make power
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11-08-2015, 10:14 AM
#11
If you're set on reusing your block, the 383 is a better option than a 347. The difference is the cost of the crank.
If you have an extra 1200-1400, the LS3 block is a no brainer. Better than the LS2, lighter than an LQ, and more cost effective than an LS7/LSX/resleeved block. So it sort of hits the sweet spot for price/performance.
If you have an extra 1200-1400, the LS3 block is a no brainer. Better than the LS2, lighter than an LQ, and more cost effective than an LS7/LSX/resleeved block. So it sort of hits the sweet spot for price/performance.
11-09-2015, 02:25 PM
#12
TECH Addict
Displacement is potential, plain and simple. So it all depends on your goals and budget and how much "potential" you want to use. Do you have a set and realistic goal? Or are you just seeing how much power you can make?
That being said, I wouldn't forge, stroke, or boost any 3.9" bore aluminum block unless the sleeves are made of ductile iron.
People get away with it, but if it's my money, then I'm not taking the chance.
My personal vote would be to sleeve the block out to 4.125", with a finished bore of 4.128", use a stock length 3.62" crank, for 387ci. You can use off the shelf CP 4.128" x 1.181" forged pistons, and eagle 6.25" forged rods, all of which are available through summit racing.
And it gives you a higher rod ratio, which is important, but I feel like a broken record bringing that up all the time.
That being said, I wouldn't forge, stroke, or boost any 3.9" bore aluminum block unless the sleeves are made of ductile iron.
People get away with it, but if it's my money, then I'm not taking the chance.
My personal vote would be to sleeve the block out to 4.125", with a finished bore of 4.128", use a stock length 3.62" crank, for 387ci. You can use off the shelf CP 4.128" x 1.181" forged pistons, and eagle 6.25" forged rods, all of which are available through summit racing.
And it gives you a higher rod ratio, which is important, but I feel like a broken record bringing that up all the time.
11-09-2015, 07:32 PM
#13
Displacement is potential, plain and simple. So it all depends on your goals and budget and how much "potential" you want to use. Do you have a set and realistic goal? Or are you just seeing how much power you can make?
That being said, I wouldn't forge, stroke, or boost any 3.9" bore aluminum block unless the sleeves are made of ductile iron.
People get away with it, but if it's my money, then I'm not taking the chance.
My personal vote would be to sleeve the block out to 4.125", with a finished bore of 4.128", use a stock length 3.62" crank, for 387ci. You can use off the shelf CP 4.128" x 1.181" forged pistons, and eagle 6.25" forged rods, all of which are available through summit racing.
And it gives you a higher rod ratio, which is important, but I feel like a broken record bringing that up all the time.
That being said, I wouldn't forge, stroke, or boost any 3.9" bore aluminum block unless the sleeves are made of ductile iron.
People get away with it, but if it's my money, then I'm not taking the chance.
My personal vote would be to sleeve the block out to 4.125", with a finished bore of 4.128", use a stock length 3.62" crank, for 387ci. You can use off the shelf CP 4.128" x 1.181" forged pistons, and eagle 6.25" forged rods, all of which are available through summit racing.
And it gives you a higher rod ratio, which is important, but I feel like a broken record bringing that up all the time.
Could an ls1 block take this and still be reliable on the street?
Would the cost be to much to justify?
What heads would be the best?
I personally love the idea, I'd build it for rpm.
11-10-2015, 09:49 AM
#14
TECH Addict
With darton sleeves, or any other ductile iron sleeves for that matter, yes you can safely stuff that size bore/piston in a ls1 block.
Ls7 heads would be the head of choice for that size bore. Ls9 heads would work well, too. Both require different intakes, etc etc.
It would be an absolute monster. And, yes, it could be made to be very reliable for use on the street. Get a really good balance on the rotating assembly, don't cheap out on things like lifters and bearings, and get a cam specifically for your application... Should provide you with years of reliable entertainment.
Ls7 heads would be the head of choice for that size bore. Ls9 heads would work well, too. Both require different intakes, etc etc.
It would be an absolute monster. And, yes, it could be made to be very reliable for use on the street. Get a really good balance on the rotating assembly, don't cheap out on things like lifters and bearings, and get a cam specifically for your application... Should provide you with years of reliable entertainment.
11-10-2015, 11:44 AM
#16
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Just my opinion but I'd go with the 347 or take the extra money you'd spend on the crank and put towards an ls2 or ls3 block or re-sleeve your ls1. A lot more head choices when you get to the 4.0+ bore
11-10-2015, 07:24 PM
#17
With darton sleeves, or any other ductile iron sleeves for that matter, yes you can safely stuff that size bore/piston in a ls1 block.
Ls7 heads would be the head of choice for that size bore. Ls9 heads would work well, too. Both require different intakes, etc etc.
It would be an absolute monster. And, yes, it could be made to be very reliable for use on the street. Get a really good balance on the rotating assembly, don't cheap out on things like lifters and bearings, and get a cam specifically for your application... Should provide you with years of reliable entertainment.
Ls7 heads would be the head of choice for that size bore. Ls9 heads would work well, too. Both require different intakes, etc etc.
It would be an absolute monster. And, yes, it could be made to be very reliable for use on the street. Get a really good balance on the rotating assembly, don't cheap out on things like lifters and bearings, and get a cam specifically for your application... Should provide you with years of reliable entertainment.
11-10-2015, 09:04 PM
#19
11-10-2015, 10:57 PM
#20
If you're set on reusing your block, the 383 is a better option than a 347. The difference is the cost of the crank.
If you have an extra 1200-1400, the LS3 block is a no brainer. Better than the LS2, lighter than an LQ, and more cost effective than an LS7/LSX/resleeved block. So it sort of hits the sweet spot for price/performance.
If you have an extra 1200-1400, the LS3 block is a no brainer. Better than the LS2, lighter than an LQ, and more cost effective than an LS7/LSX/resleeved block. So it sort of hits the sweet spot for price/performance.