5.3L Build for 84 944 5 speed.

I'm new to building and swaps. I'm working as an intern at a place that build race engines in auburn hills,MI got a 5.3 LM7 iron block and some parts off a coworker and I'm building it with his help since he's been doing it for years. i have the 5.3 iron block(need to get blasted because of some rust), 5.3 headers like new I've cleaned them up soda blasted them and sanded the deck and surfaces where gaskets go, have a truck oil pan which I've cleaned out and about to take all the pieces off of and soda blast to make it look like new (I'm curious if i can use the truck oil pan since its so deep), if got my hands on a ls1 intake manifold with stock injectors and fuel rail( only problem is one of the places where there should a bolt hole its broken), almost new LS1 crank, planning on running a @.050 226/232cm with 114 lobe separation (spirited street and some track driving ) ill post more info soon once i get everything sorted out. debating if i should send out my heads and get CNC ported and also gonna bore the engine to 3.800 and run stock stroke. still trying to figure out what rods and pistons i wanna go with I'm going forged forsake though. any tips hints and recommendations are greatly appreciated.ill also be posting pics of everything i have. i was planning on keeping my stock trans because its recently been rebuilt also.

welcome to the forum.

just a few things to comment on your build, and specific to the 944 swap. the truck pan will not work, in fact, no factory ls pan will. there is a specific oil pan you have to run to clear the crossmember. the factory "headers" (manifolds) you mentioned also wont work in a 944, but there are a couple different options for headers designed specifically to fit the 944. also the n/a transmission will work, however it is far from ideal. the 3.889 final drive makes is too short to make good use of the power, along with being weak. the 944 turbo has a 3.37 final drive, and swapping the 5th gear set from the n/a transmission will give you nice low cruising rpm. the turbo transmission also has a stronger mid case section. limited slip diffs and oil cooler systems were also options on the 944, so thats more to consider.

as for the engine, sounds like you have it sorted. boring it to 3.800 (.020) over isnt going to do much for power, but if the bore needs a clean up its a good idea. you can also use 4.8l flat top pistons to bump the compression to 10:1. i wouldnt put too much into the lm7 heads, imo it would be better to start with a set of 243/799 castings. the lm7 heads will work just fine, just not worth cnc porting.

Question. Could I run a 4.000 crank wth 6.125 rods in the 5.3l and what height piston would I be able to use

Moose,

This is the world's best resource for LS 944 swaps, but perhaps not the best for detailed engine building. Head on over to LS1tech for anything you need to know about your engine. They were my bible when I built my engine.

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Good luck,
Gord.

sharkey wrote:welcome to the forum.

just a few things to comment on your build, and specific to the 944 swap. the truck pan will not work, in fact, no factory ls pan will. there is a specific oil pan you have to run to clear the crossmember. the factory "headers" (manifolds) you mentioned also wont work in a 944, but there are a couple different options for headers designed specifically to fit the 944. also the n/a transmission will work, however it is far from ideal. the 3.889 final drive makes is too short to make good use of the power, along with being weak. the 944 turbo has a 3.37 final drive, and swapping the 5th gear set from the n/a transmission will give you nice low cruising rpm. the turbo transmission also has a stronger mid case section. limited slip diffs and oil cooler systems were also options on the 944, so thats more to consider.

as for the engine, sounds like you have it sorted. boring it to 3.800 (.020) over isnt going to do much for power, but if the bore needs a clean up its a good idea. you can also use 4.8l flat top pistons to bump the compression to 10:1. i wouldnt put too much into the lm7 heads, imo it would be better to start with a set of 243/799 castings. the lm7 heads will work just fine, just not worth cnc porting.

What sharkey said times 2

What sharkey said times 3
What murrayg said times 2

Never mind I figured it out lol got the deck height figured out and did the math it'll work! So update haha planning on running forged rotating assembly 4.000 crank with the 6.125 rods and most likely going with mahle pistons. Gonna keep same bore 3.800 aiming for higher compression.

Got the block back got her cooked and peen blasted. [You must be registered and logged in to see this image.]

Next step is to get her decked and bored to 3.800

Just throwing it out there, in stead of going with higher compression, depending what it is stock, if its under 10:1 go to 9:1 or less and add a turbo, retain good mileage and plenty of spunk with the boost. As far as heads go, if a stock LS3 head will bolt on no porting needed. There is not a lot of significant gains on my LS3 heads stock versus porting. I did a lot of research and for the dollar verse the gains not worth it. When i did my motor in hind site i would have reduced the compression for now and then added a turbo or a supercharger. But at the end of the day its all about what you want for HP. My little LS3 will produce over 500 HP so i think i am good. Enjoy the build. Just about anything you want to know about the swap is here.

imo you can extract more than enough power from an ls engine to destroy our transaxles while still being n/a and very streetable. it just seems like a heck of a lot of work and money to fab up a turbo setup and only make 500hp.

Welcome!

good stuff..