Hello all,
I'm sure this isn't a new question that I'm asking here, but hoping to get some feedback / justified opinions from others that are more experienced than me. I've never done an engine swap in a C5 corvette.

My 99 C5 currently has the stock LS1 with 155K miles. It's starting to show it's age I feel like. I don't think I really want to upgrade it which I had considered at one point. Now I'm leaning more toward just replacing it.

I've basically narrowed it down to 3 choices
1) Just get another LS1 and rebuild it possibly with a few upgrades like some LS6 Heads and such. Maybe consider a cam and some other misc stuff as well. - If I did go this route I'm wondering what people would consider for reliable upgrades that will maintain the drivability feel of stock. I wouldn't want to go too crazy, 90% of the time this car is weekend cruising. I would only take it out on a track maybe a couple of weekends a year to just have some fun driving and not concerned with times.

2) Second option would be to just go ahead and go with an LS6. Again possibly with some recommended upgrades.

3) Last option is an LS3. I know this is probably the most difficult and expensive because I'd have to buy some harness adapters and such. But overall it doesn't seem to be too bad based on what I've read. I don't I'd really have to do much upgrading if I went this route as it's already pretty much at the high end of the numbers I'd want to be at for this is a street car. But I'd still love to hear any mild upgrades that make it more fun that anyone has to suggest.

I guess one other possible option is going completely off the LS path and just getting a crate engine. Just seems like that is potentially the most complicated to find the right one and make everything fit and connect properly.

But, I would say my budget is I'd like to try and stay under maybe 8k on the high end. From what I can find that is going to make LS3s and crate engines really hard to do unless I find a good deal. And for some reason it looks like LS6s are going for as much as LS3s right now (no idea why that is). I could probably wait a few more weeks / months to save up a little more if I needed to, but would be great if there were options to go with soon.


I am not hugely experienced with engines or engine swaps, will be muddling my way through it. I'm good at following directions and figuring things out though. I did do a couple of engine swaps in some older vehicles many many many years ago. So, I'm sure all that information and knowledge from then is about as good as a lump of coal :P But I still want to do this myself because I've done everything else on this car myself (full suspension upgrade and a transmission / rear end swap).

I welcome any feedback and suggestions, even those beyond what I've put here. Just please give justification on your suggestions. I'd want to know why people are recommending one option over the other.

Thanks!

 

You would be much better off installing an A&A blower setup. A LOT less work, and 500whp easily. As for 150,000+ miles, if the motor has been maintained, you aren't even halfway thru the engines life. I went with a built LS7 swap in my 2000 C5. I wish I'd known then what I know now. Reliability and big power are why the OEMs have gone FI. I'd NEVER go with a built NA engine again. Amazing how history repeats itself. In the 1950s, some cars came with blowers and an OD transmission!

 

What does showing its age mean? No way I’d go through the effort of pulling the engine to put another ls1/6 back in. Unless something is wrong with your engine build what you have or go LS3 if you really want to swap it.

 

It's noticeably down on power for one thing. I haven't dyno'd it or anything but I've driven other LS1 corvettes and mine has noticeably less torque at least. The compression numbers also aren't amazing. The lowest is at 151 and highest is at 176 last time I checked. So it is quite a bit above the 10% spread I see as a rule of thumb. I've also read these LS1s should be closer to 180, so 151 seems really low. The engine just overall seems "tired" is the best way I can describe it lol. I don't know it's maintenance history before I bought it. Recently I've started having problems with big temperature fluctuations in it also. On hotter days I'm seeing the temps climb up getting close to the red line if I'm accelerating hard. I replaced the temp sensor thinking it might have been a problem but it still does it some. I don't think it's a tstat problem, it seems to be opening and closing properly when I've checked it. I replaced the coolant in it as well, didn't see any gunk or debris in it when I drained it and levels have maintained since doing that.

Last time I did the compression tests and replaced spark plugs, at least one of the plugs had oil on the threads. And there is a small amount of bluish smoke from the exhaust.

In addition to that, recently I noticed there is a little bit of wobble in the crankshaft pulley (EDIT: I call it wobble, but that might be a misleading term, it doesn't seem to be loose or anything like that, hard for me to describe it otherwise though). It might be normal, I'm honestly not sure yet. I just saw it when I was trying to figure out where a squeaking noise was coming from a couple of weeks ago. Haven't really looked into that more yet.

So, I really think it might need piston rings at the very least, but possibly more. And if I have to pull the engine anyway to do that, I figure I might as well just replace it. The idea being I'd have the new one ready to go to swap in when I pull the old one so it's not sitting around without an engine at all for a while.

I also don't mind doing it even if I end up finding out it was unnecessary because this is my hobby car and I enjoy turning wrenches on it when I have time. :P I'd most likely rebuild the engine in the car now after pulling it just for fun if nothing else and then maybe buy another project car to put it in hehe

 

Sounds like your balancer is failing. I agree with the post about swapping in another LS1/LS6. If youre going to the trouble of yanking the motor, Id put a bigger motor in it, 6.0 or 6.2, and stay with the aluminum block.....