alright, so lets get to it. Im in the midst of LS1 shopping and I found a pretty good deal on a 4.8 LR4 truck block assembly. Im looking into the cost of making it as powerful as possible, and from everything i have read, this is what I have come up with, I am looking for someone to tell me wher I am wrong and what else I need to know!

1) the 4.8 and 5.3 block are the same, only using longer rods in the 4.8. So it can be bored out to 94.00mm and will accept LS1 rotating assembly with no problems. So now you basically have a iron block LS1 bottom end.

2) this bottom end will be stronger than an aluminum bottom end due to the iron block, so it would be more ideal for forced induction or N02 application assuming you use the later improved LS1 assembly

2) the heads on the 4.8 and 5.3 are also the same (the 5.3 pistons are just dished, whereas the 4.8 uses flattop) so any LSx heads should bolt upwith out any valve intrusion to the pistons. Which heads would be best to use when concidering flow and CR?

3) the camshaft choices would be limited to only truck cams as the OD of the journals of the are larger than those of the aluminum block LS's The rest of the valvetrain however is interchangeable.

4) you have your choice in intake manifolds, the truck intakes are about 3-4 inches higher than the LS1 LS6, so for space reasons I can use one of those.

now for some questions I have -

1) what oiling system should I use? are all the oil pumps the same?

2) are the harnesses the same? I understand it is supposed to easy to switch to a LS1 PCM, are they just a simple plug in, or is some splicing needed?

3) what sensor differences are there? knock, MAF, etc.?

4) what am I missing!

I would like to make an educated perchase here, so am I going to spend more parts nickel and diming like this? should I just go LS1 crate? I would DEFINATELY APPRECIATE ANY FEEDBACK or any assistance anyone has!!

thanks,
steeve

 

Steve,

I depends a lot on what you're looking to achieve. An LR4 pull-out, complete with all accessories can usually be had far cheaper than an LS1, and they're very plentiful at very low mileage. If cost is your objective, then the truck motor, either 4.8L or 5.3L will satisfy that. A few more $$ will get you a 6.0L or even an LQ9 (345hp 6.0L truck/SUV).

The 5.3, 5.7, and 6.0 all use the same crank and rods (except the early 6.0L cranks are different at the flange). It's only the 4.8 that has a shorter stroke and longer rods.

If you're piecing a motor together, and your target is a 5.7 iron block motor, then why not simply start with a 6.0L? Same crank and rods as a 5.7, but with slightly larger pistons. FWIW.

Andy1

 

4.8/5.3s have a smaller bore than LS1s. 5.3s do have the same crank though. 4.8s have a smaller crank. the sensors are the same on all 3 motors. unless you are getting this complete motor for like $200 IMO its not a good deal.

 

sorry to highjack the thread, but what are good donor cars (trucks) for the 6.0L iron blocks?

 

3/4 ton

 

About the cast iron vs. aluminum blocks, think of the weight trade-off as well. The aluminum LS1 block is well tested even at high power levels. The only reason I would go with a cast iron block on a build less than 800rwhp would be for cost savings.