LS4 Crank Question....
Thread Starter
On The Tree
Joined: Jan 2010
Posts: 168
Likes: 1
From: Fort Campbell, KY
LS4 Crank Question.... I'm thinking about running a LS4 when I swap out my V-6. I know an LS4's crankshaft is shorter in the front, and I think that will be a show stopper when I start putting an L99 style accessory set-up togather.
My question is this, is there any reason why I can't run a crank from another LS engine with the normal length? I'm hoping I can get away with it so I can use all the L99 parts for the front. (Oil pump, front cover, accessories, etc.)
My question is this, is there any reason why I can't run a crank from another LS engine with the normal length? I'm hoping I can get away with it so I can use all the L99 parts for the front. (Oil pump, front cover, accessories, etc.)
The LS4 crankshaft is 10mm shorter on the accessory end AND 3mm shorter on the bellhousing side.
https://ls1tech.com/forums/ls4-perfo...-4t65e-hd.html
The shorter crank and the block extension for the metric pattern (to clear the rear cover bolts) places the crank flange flush with the metric bellhousing face... requiring a thicker flywheel combo if used in a RWD configuration.
The other issue using it for an engine swap is the Metric pattern on the LS4 does not allow a 168 tooth flywheel to be used. The 168 is about 2" larger in diameter than the 142 tooth ring gear the LS4 uses. The 168 tooth ring gear passes through several of the Metric bellhouising bolt locations eliminating its possibility of use. Also, the LS4 blocks do not have the traditional RWD starter provision since the block was clearanced on that side to fit the 4T65e-HD transmission.
To swap one in in a RWD configuration, you will need to build a starter mount in the stock location, but I am not sure you can get the starter close enough w/o major oil pan surgury, there is also the option of using the GM LS4 prototype oil pan to put the starter under it, or you can make a custom bracket to mount it on the transmission (then you could run into transmission tunnel clearance issues).
Here is a picture of the LS4 prototype oil pan w/starter:
Here is the bracket I made for my F40 6 speed swap to mount the stock LS4 starter in the stock LS4 location for my swap (kept it transverse):
https://ls1tech.com/forums/ls4-perfo...-4t65e-hd.html
The shorter crank and the block extension for the metric pattern (to clear the rear cover bolts) places the crank flange flush with the metric bellhousing face... requiring a thicker flywheel combo if used in a RWD configuration.
The other issue using it for an engine swap is the Metric pattern on the LS4 does not allow a 168 tooth flywheel to be used. The 168 is about 2" larger in diameter than the 142 tooth ring gear the LS4 uses. The 168 tooth ring gear passes through several of the Metric bellhouising bolt locations eliminating its possibility of use. Also, the LS4 blocks do not have the traditional RWD starter provision since the block was clearanced on that side to fit the 4T65e-HD transmission.
To swap one in in a RWD configuration, you will need to build a starter mount in the stock location, but I am not sure you can get the starter close enough w/o major oil pan surgury, there is also the option of using the GM LS4 prototype oil pan to put the starter under it, or you can make a custom bracket to mount it on the transmission (then you could run into transmission tunnel clearance issues).
Here is a picture of the LS4 prototype oil pan w/starter:
Here is the bracket I made for my F40 6 speed swap to mount the stock LS4 starter in the stock LS4 location for my swap (kept it transverse):
Last edited by fieroguru; Apr 16, 2011 at 07:07 AM.
Thread Starter
On The Tree
Joined: Jan 2010
Posts: 168
Likes: 1
From: Fort Campbell, KY
The transmission section let me know of the lack of starter mounting in another thread, but none of them offerred a solution either. Now that I've seen your set-up, I don't think adapting a starter would be impossible. Building a bracket much like the one you have, is within my means in my shop.
The smaller flywheel diameter is the thing that is making me want to use a truck 5.3 with a 3rd gen V8 bell housing for my T-5 instead. But is is nice to know I still have good options if I stick with the LS4.
btw, those pictures will be very helpfull. Thanks
The smaller flywheel diameter is the thing that is making me want to use a truck 5.3 with a 3rd gen V8 bell housing for my T-5 instead. But is is nice to know I still have good options if I stick with the LS4.
btw, those pictures will be very helpfull. Thanks
