Maximum bore on LT1 block.
05-04-2004, 02:02 PM
#16
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Are there any clearancing issues using a 4.125 stroke? I've seen stroker cranks for the first gen smallblocks that big but never for the LT1 specifically (i.e., one piece rear main seal). Where do you get a stroker crank that big?
05-04-2004, 02:05 PM
#17
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Originally posted by Injuneer
There was a performance shop that used to sell a 409ci short block LT1, but he no longer has it in his catalog.
There was a performance shop that used to sell a 409ci short block LT1, but he no longer has it in his catalog.
05-04-2004, 02:40 PM
#18
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http://www.cmotorsports.com they sell a 409 too.
05-04-2004, 03:00 PM
#19
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Originally posted by Injuneer
There was a guy who used to post on here that claimed to have built two different versions of the LT1 at 421ci. One was a 4.030" bore x 4.125" stroke. The other version was a 4.090" bore X 4.00" stroke. I saw the dyno sheets for the 4.090 bore motor, and it made over 800HP on the juice. He had to have the entire block soniclly checked for wall thickness, then recenter the bores to put most of the meat on the thrust side of the cylinder. Seems like a huge waste of effort.
There was a guy who used to post on here that claimed to have built two different versions of the LT1 at 421ci. One was a 4.030" bore x 4.125" stroke. The other version was a 4.090" bore X 4.00" stroke. I saw the dyno sheets for the 4.090 bore motor, and it made over 800HP on the juice. He had to have the entire block soniclly checked for wall thickness, then recenter the bores to put most of the meat on the thrust side of the cylinder. Seems like a huge waste of effort.
maybe a lot of torque.
Can anyone else back this up?
05-04-2004, 03:54 PM
#21
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Originally posted by Eff
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
The man knows his stuff!!!
05-04-2004, 04:30 PM
#22
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Originally posted by Eff
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
05-04-2004, 04:37 PM
#23
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Originally posted by LT4POWR
I wouldn't question anything Injuneer posts. The man knows his stuff!!!
I wouldn't question anything Injuneer posts.
The man knows his stuff!!!
But it's not him that I question. It's that guy that claimed to have built that engine.
This is why.
Stock lt-1. the rod ratio is roughly 1.637 (5.7/3.48)
The ideal rod ratio is usually considered to be right around 1.81
however getting this would be next to impossible in an lt1. a couple Mopar engines are the only ones I know of with ideal rod ratios.
(4.125-3.48)/2=.3225
This is the 1/2 of the difference in stroke. which would have to be compensated for by shorting the rod or piston to preserve deck clearence. If just the rod was shortened it would need to be shortened to 5.3775 this would make a ratio of 1.303 Even with the smallest piston height, you would still be extremely low. This seems like it would create a huge drag on the engine. This is why I say it would probably make a signifigant amount of torque. but I don't know about HP.
Seems like clearence would also be a problem.
Then again I'm no engineer. maybe it would work and make 800HP. Just seems to me if you are going to sacrifice that much power to make power, there has got to be a better way.
If any engineers or Extremely experienced engine builders read this I would be curious to know what is thought to be the lowest rod ratio that should be used.
05-04-2004, 05:31 PM
#24
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Originally posted by Eff
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
hmmm..... Don't sound right. 4.125 stroke on an lt1 would put the rod ratio so high, that I can't imagine it actually making 800hp.
maybe a lot of torque.
Can anyone else back this up?
With that kinda stroke this HIGHEST POSSIBLE rod ratio would be 1.44. Thats with a 5.96 rods (not that you could find those anyway) and 1" CH pistons (bad for rings). Either way its rediculiously low.
05-04-2004, 09:22 PM
#26
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Id say it is more work than it is worth. The engine would be a torque monster, but would have a very low redline. You would also have to clearance everything and have oil pan issues. Honestly you could make a MUCH better 396 than a 421. With a rod ratio that low, it puts serious stress on the cylinder walls, rings, and rods. The biggest stroke that I would go with on a LT1 would be a 4" and even then it is pushing it.
If you want a daily driver then go with a 396. Honestly if you wanted an all out race car, then you could make a 355 with 6.2" rods have a rod ratio of 1.78. Get strong lightweight internals and rev the CRAP out of it. That would make MUCH more power, but wouldnt be streetable at all.
If you want a daily driver then go with a 396. Honestly if you wanted an all out race car, then you could make a 355 with 6.2" rods have a rod ratio of 1.78. Get strong lightweight internals and rev the CRAP out of it. That would make MUCH more power, but wouldnt be streetable at all.
05-04-2004, 11:39 PM
#27
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If you are interested in the opinion of engine builders with respect to rod/stroke ratio, you might want to go over to Advanced Tech and try some searches. We've discussed the subject in a number of threads.
05-05-2004, 06:47 AM
#28
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So did anyone ever dig up the dyno sheets for that 421 or 427 or whatever the hell it was? I'd be curious to see them. Honestly, I don't think I'd try to build something as big as a 427 with an LT1 (for the money I think I'd say f*** it and just stick a big block in there). But I might be interested in a 409. I like the idea of the additional torque (however much that would be over a 396, I don't know).
05-05-2004, 08:52 AM
#29
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Originally posted by disco192
Id say it is more work than it is worth. The engine would be a torque monster, but would have a very low redline. You would also have to clearance everything and have oil pan issues. Honestly you could make a MUCH better 396 than a 421. With a rod ratio that low, it puts serious stress on the cylinder walls, rings, and rods. The biggest stroke that I would go with on a LT1 would be a 4" and even then it is pushing it.
Id say it is more work than it is worth. The engine would be a torque monster, but would have a very low redline. You would also have to clearance everything and have oil pan issues. Honestly you could make a MUCH better 396 than a 421. With a rod ratio that low, it puts serious stress on the cylinder walls, rings, and rods. The biggest stroke that I would go with on a LT1 would be a 4" and even then it is pushing it.
Originally posted by disco192
If you want a daily driver then go with a 396. Honestly if you wanted an all out race car, then you could make a 355 with 6.2" rods have a rod ratio of 1.78. Get strong lightweight internals and rev the CRAP out of it. That would make MUCH more power, but wouldnt be streetable at all.
If you want a daily driver then go with a 396. Honestly if you wanted an all out race car, then you could make a 355 with 6.2" rods have a rod ratio of 1.78. Get strong lightweight internals and rev the CRAP out of it. That would make MUCH more power, but wouldnt be streetable at all.
