Differences in LT1/LT4 short block
Thread Starter
Safety Car
Joined: May 2007
Posts: 3,651
Likes: 10
From: Apple Valley MN
Differences in LT1/LT4 short block
One possible option for fixing my LT4 (spun bearing) is to replace the short block with an LT1 (4-bolt main). I know the pistons, rings and crank are a little different - how much impact does this have on the rev limit?
Team Owner
Joined: Mar 2001
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From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Thread Starter
Safety Car
Joined: May 2007
Posts: 3,651
Likes: 10
From: Apple Valley MN
Yep, I know - the factory redline on the LT1 is several hundred RPM below the LT4, and 100 RPM under the LT4's peak HP RPM. I guess what I'm asking is how much of that difference is attributable to the short block itself? I read somewhere that the max RPM for LT1 rods is about 6200 RPM. If this is true, then I'd likely need to lower the rev limiter?
Team Owner
Joined: Mar 2001
Posts: 30,858
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Read the link, it's all in there.
The cranks are machined differently.
I wouldn't rev it as high.
BTW the fully forged rotating assembly for my stoker was around $1500
The cranks are machined differently.
I wouldn't rev it as high.
BTW the fully forged rotating assembly for my stoker was around $1500
Drifting
Joined: Apr 2007
Posts: 1,291
Likes: 33
From: Chicago IL
Any reason you do not want to do a rebuild? The LT4 is the best gen 1 small block ever made by gm so why downgrade to a LT1?
1 step forward, 2 steps backwards.........
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Le Mans Master
Joined: Dec 2006
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From: H-Town Texas
It's very possible that all you need to replace is the crank, the bearing set and possibly the rod where the bearing spun. The Rod and bearings are fairly inexpensive, the crank may not be. But, there are alot of people on this forum and I'm sure elsewhere that upgraded to a stroker that just might have the LT4 crank sitting in box in the basement somewhere.
Check out ebay, put a WTB post in the for sale section. You might be suprised.
Check out ebay, put a WTB post in the for sale section. You might be suprised.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Seen many threads about the LT4s mainly but many LT1s too spinnign bearings, some of them with low miles too. Some member posted here a week or so about his sub 30k mile car spinning one, I dont get it.
Has to be a design fault somewhere, they just cant "go bad" like that.
Has to be a design fault somewhere, they just cant "go bad" like that.
Pro
Joined: Jan 2009
Posts: 686
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From: Austin Texas
thanks
Pro
Joined: Dec 2008
Posts: 512
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From: Denton TX
The cost of pulling the engine is in either scenario fix old or replace with new short block....You will basically have a new engine with the short block...in either scenario...depending on miles...you will want to have the heads worked....new oil pump....and new gaskets.... etc...You might save some time... At the end of the day..with the short block in the hole ..you have another block and parts to start a 383...when the other engine goes south.
Drifting
Joined: Jan 2006
Posts: 1,740
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From: Winchester Virginia
Drifting
Joined: Apr 2007
Posts: 1,291
Likes: 33
From: Chicago IL
