Hacker News Reader

Comment by specialp | Hacker News Reader

I built an LSX (Aftermarket GM) iron block engine (V8 LS) for a CTS V. I had to get some very precise tools (Have to measure to 10,000ths) or they were useless for bearing clearances and verifying cylinder diameters. My cylinders were 4.155 bore, and the bearing clearances were around 1.8 thousandths. Forged pistons, rods and crank.

I had cracked a cylinder/piston on the original LSA. I did not trust anyone to do the work so I did a lot of research and did it all myself. I appreciate someone asking because my friends and software dev co workers aren't interested :)

View on HN

Yes you are right as far as LS engine builders there's loads. I could have ordered a crate engine from Texas Speed and been done with it. And yes for hours of my time spent vs hours of money saved I lost a ton of money. But all it takes is one very small mistake to make an engine short lived with these exacting tolerances. I'd rather blame myself than deal with someone kicking the blame back. It was also a personal satisfaction thing.

My wife's engine had an issue and it was the middle of winter so I said whatever let's just have a shop fix it. In the process they "flushed the transmission" and it failed 4 days after we got the car back. Of course they stonewalled us and I can't prove they broke it. So I ordered a late model wreck transmission and replaced it and 3 years later still running strong.

But I then decided that I would never be in that position again where someone could tell me it wasn't their problem and get me aggravated. With this engine I built it from raw parts. I had the block machined, and I had the tools to verify.

It was certainly not worth my time, but as you said I love working on cars too.

I have a buddy that is adamant about not flushing transmissions if you dont have a issue because he think its guaranteed to have an issue after, from his experience. lol

There is some truth to that, but not never. A flush will dislodge any metal shavings and crud from the moving parts. The filter should catch these, but the filters themselves can get clogged, and then bye-bye transmission.

Flushing can really be bad if you've never done a routine flush on a schedule. You don't want to go 150,000 miles before your first one. You would need a garage with a forced flush system to move it all out, and then probably flush again soon after to make sure all the gunk is out.

Transmission oil breaks down with heat and wear like any other, and will eventually contain sludge and dirt.

I'd concur with that. Note this was one of the notorious to fail JATCO nissan/mitsubishi transmissions. Blowing fluid through with pressure makes no sense. Sediment sitting in pans does not affect operation until it is agitated into suspension

The Nissan automatics and especially manuals(cd009) are fairly strong. It's their CVT that's the issues. I don't know why Nissan insist on using them with their V6's.

>I had cracked a cylinder/piston on the original LSA. I did not trust anyone to do the work so I did a lot of research and did it all myself

I love working on cars so I totally get wanting to do that, but why didn't you trust someone else to do the work? There are probably more reputable LS builders across the US than any other engine family.

It sounds like he wanted some very precise work done. Quality in the blue collar trades has gone to nil in the last decade. And if you do find someone that is very detailed and "by the book" level of quality, you are going to pay 3X the normal labor rate. For instance, this is a performance transmission shop [0] that regularly takes apart "precision" rebuilt transmissions only to find they were not done right at all.

[0] https://youtu.be/aI5iO2YSHMs

LS engines are among the most common engines in custom built cars, and there are countless shops out there who specialize in them. No offense to him or you, but it's quite ridiculous to believe you can do a better job building an engine on your first try than shops like Texas Speed who have been doing it for decades with full blown R&D labs and regularly build 2000+ horsepower motors, all with highly skilled machinists and engineers using professional equipment that the average person would never be able to afford.

Edit - For reference here's a video of the shop I'm referring to. They're far from a podunk operation. https://www.youtube.com/watch?v=8HgwF5dISmU

I could do a better job than them in all due respect. I care about my job more than anyone on earth. I know they do good work but if we could both measure to the same specs and know we did it right, how could I do it worse than them. we have the same measuring tools. Not that I think they do bad work. But if you ever built an engine you know its all about attention to detail. there is nothing they have to verify the integrity of the build that I don't to a similar level of precision.

Edit: I dont have the machines they do, but when my bare block comes back from the machine shop, my tools are just as good as theirs to verify the dimensions are correct. That isn't possible to verify with a built short or long block. They could possibly have 100 employees that care as much about my job as me who knows. This is a job about verification of specs and assembling correctly not of insane tech. They don't have anything I dont when assembling an engine. Machine work yes

Texas Speed or TKM are two places I’d use if I were doing an LS build.

It helps that they are abundant (in the hundreds of millions units produced), have been in use for decades (since the mid-50s), and are simple to work on (as evidence by the OP randomly learning to machine one).

As cool as 2-atom thick plasma transfer wire arc cylinder liners are, that's not something which will ever be available to a layman.

I really doubt the OP did the machine work himself, those tools are not affordable for just using once or twice. Buying bore gages and mics however is totally doable.

And no, the LS motors have been in use since '97. Including the gen1/2 small blocks doesn't count, there are no shared parts between them.

17-18 thou here on my LS6 on the rods. 23-24 on the mains. I'd like to see tighter on the mains, but not sure if its worth ordering another set of bearings and using 1/2 of them to tighten up 1/2 a thou like i did on the rods.

what amazes me is the cam lifts we're running these days. I'm running .646"/.649". In the 90s .500" was big for a street motor, and only full blown race motors were running whats normal now.

Damn, dropping a new engine in a CTS V? What year? NA? How much power are you shooting for? The CTS V is definitely one of my favorite cars, I'd love to own one one day, but the ones with the manual trans hold their value pretty well :)

It was and still will be supercharged. It was 650 crank Hp, and will be over 800 conservatively . and its manual ;)

Yep. Jealous. Best of luck on the build!

Very cool. Although I own an LS, I've never touched an LS. The Sloppy Mechanics guy is impressive though.

Since a short block is mostly just a short block, I'll be interested in seeing if LS heads/intake manifold/headers takes off in the SBC community.

Huh? What do you mean "takes off". Do you mean do we build LS motors now instead of gen1/2 SBCs then yes.

If you mean "do the LSx heads drop onto a gen1/2 SBC", then no, not at all. only thing common between them is the cylinder spacing. The LS uses 4 bolts per cylinder like a ford, instead of 5 like the SBC, the firing order is different, the valve layout is different (ports are symmetric vs mirrored), etc.

Firing order is something of an arbitrary thing, it's been done on SBC for some time.

There are small block Chevrolet blocks that accept LS heads (Bill Mitchell maybe?)

(note: I wasn't referring to box-stock LS heads on a box-stock SBC)

Mostly what i've seen is making the SBC take a symmetrical head. Saw some INSANE CFE pro stock heads at the machinist last year, he was building them in a large bore, short stroke deal setup for bonneville to run like 11krpm.

Why did you go iron block for your build? Is it that your were afraid you cracked the block again? How did you do that in the first place. Are you running any boost on this engine?

I'm running 14 lbs boost yes. And yes it was piece of mind that it's much harder to crack and unlike the aluminum block I can bore it more than 5-10 thou if it needed it again. Downside is 100lbs more but this is in a 4200lb car so whatever

Reply on news.ycombinator.com