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I am 100% new to chevy motors....
I just tore my lq4 apart and found 2 bad cam bearings...I could just pop them out by hand...
I also found one rod bearing that was damaged too.
So, today I took the block to the machine shop.
They said my crank needs to be ground down GM says nono tho many people say its been fine...
So I think Maaan funnnk that lets stroke it 408....It won't cost much more at this point....
My plan is to do the 408 kit linked below and 832 heads and ls3 intake.
I think it should be around 10.2:1 with this setup perfect for a street/track toy.
I figure I'll have my BTR cam reground at Delta Cams local to me (still looking at what lift/duration id use there).
The goal is a reliable 500WHP that is safe for 91 octane and should be over-engineered for my power goals so it will have OEM longevity.
well i cant answer weather or not to stroke it, but summit has some nice forged rod/piston kits. we did a lq4 using the stock crank and the summit kit (rods/pistons) bored it .030 and made a nice 370 lq4 at about 10.8:1 and it runs great. if you do want to make a 408 it wouldnt be that much harder it all just depends on how much you want to spend on the crank. summit has some nice stuff for the price.
well i cant answer weather or not to stroke it, but summit has some nice forged rod/piston kits. we did a lq4 using the stock crank and the summit kit (rods/pistons) bored it .030 and made a nice 370 lq4 at about 10.8:1 and it runs great. if you do want to make a 408 it wouldnt be that much harder it all just depends on how much you want to spend on the crank. summit has some nice stuff for the price.
no doubt. I’ve been browsing their website. With the world of rebranded Reeb boxing parts, I prefer to buy from a legitimate supplier, such as summit..
I took my motor to the machine shop yesterday and they said the crank needed to be ground.
I’ve read that that’s not the best idea, at least, according to GM.
So they got me thinking maybe I should do a stroker. Initially, I was just gonna use new bearings and rings and send it. however, the deeper and deeper I dive in I want something that’s gonna last longer. I don’t wanna do this again in two years. I’d like to drive the car for a while and enjoy it.
I don’t think a stroker is the best option on the iron blocks from what I understand. They have shorter sleeves in the aluminum blocks. Everybody says it boost ot… I don’t want to boost I don’t wanna deal with the added maintenance and headache of boost. Thank you for the reply.
I would run a 408 with no concerns. Ton's of people using them since the LS engine first came out and I've never heard of any major issues. You do need a competent machine shop to spec the proper piston for that application but if that is done, i would not be worried and do it myself for sure.
OK, proper spec the pistons...
Does that mean let them buy the parts?
Or as my machine shop wants me to do, get the kit and bring it in so they can spec everything.
If you go stroker I would have to have a clear understanding with the machine shop if you supply the stroker kit in regards to standing behind their work. Not trying to say the machine shop won't stand behind their work. But most shops get nervous with customer supplied parts.
So I went up and talk to John today. They are a very well established shop out here in the tacoms metro area.
He took me in the back and showed me a bunch of sleeves. He explained to me that he has stroked 6 L Chevy motors with 4” before but he doesn’t recommend it. He then showed me with two different sleeves why. Just like it is described the piston comes down so far the skirt hangs out at rocks back-and-forth had best. It burns oil and they don’t last as long. The ls motor is known for his longevity and in a the 408 just isn’t UNLESS you reslreve..
So, I think I’m just gonna take this block throw it in the corner for a while and try my luck with an LS1 5.7 that I found nee bearings pistons rods and rings all done at the machine shop. I’m not looking for boost at all or super high horsepower. I just bought a car blown motor and got fucked that’s all.
i will say as a testament to how badass these motors are you would’ve never known there was anything wrong with it. I’m a seasoned wrench. The car had no rod knock. Ran great. I only drove it about 150 miles before I decided to change the oil, I guess it’s a good thing I did that. she sure can suck ! Block is good Crank needs polished maybe ground according to the machine shop. Which I think it probably needs to be ground because there’s a couple spots where you can feel it The spun rod bearing. This was the metal I seen in the oil pick up tube. I’m sure had I driven it anymore. I it would’ve completely seized… I suspect the person I got the car from did a Shawty job on his work. He said he did the main bearings, but the main bearings are marked GM the rod bearings are marked clevite. Should’ve ever trusted this dumbass. but the car ran. Great, sounded great and was too fun to drive. I had a Dino sheet that showed 400 wheel horsepower. The cam bearings were so cooked. I was able to push two of them out by hand All the burrs. The thing is smoked it pretty much wiped out my cam too I don’t know what to say about that. Scorching on the cam. The machine shop said it’s probably OK Main bearings are tossed too, but they’re in the best condition of everything
hey summit get in here and please talk about how pistons have changed in last decade to solve stroker bore rock. pretty sure the skirt and or ring location have changed to make this a non issue. someone correct me if im wrong.
It's long been said that stroking the LS block can lead to longevity issues due to the piston skirt coming too far out of the cylinder sleeve. How they remedied this was by relocating the wrist pin higher up in the piston and running a shorter compression height piston. To some professional engine builders it's a (X::X) but the LS 408's up to the poor mans 427 are still being built and for those hardcore racers who go back into their engines more often than others it's no big deal. I would not be afraid to stroke the LQ4 to 408.
Iron block has more cylinder length than aluminum. There’s a mod here who has been running a 4.25 stroke in a 6 liter iron block for a longtime now with no issues. It’s all about piston design, as kjduvall mentioned above. It has come a long, long way in the last several years. Wiseco particularly has done their homework for stroker apps. Don’t be afraid of it, unless your wanting an honest 100k miles out of it…then you better stay stock.
It sounds like you need a new machine shop...OR just build it yourself. I can't speak to the LQ4, but the gen-4 iron blocks have the same sleeve length as what the aluminum blocks are advertised to have. The last 2 engines I built were gen-4 iron blocks (LMG and LC9). They have the same sleeve length. I haven't measured an aluminum block yet. I have a bare 6.2L block in my shop. Maybe I should go measure it......
It sounds like you need a new machine shop...OR just build it yourself. I can't speak to the LQ4, but the gen-4 iron blocks have the same sleeve length as what the aluminum blocks are advertised to have. The last 2 engines I built were gen-4 iron blocks (LMG and LC9). They have the same sleeve length. I haven't measured an aluminum block yet. I have a bare 6.2L block in my shop. Maybe I should go measure it......
The 6.2L block (L92) that I have, measured differently in every bore. I measured from 5.567" to 5.605". I guess that's why they like to "zero deck" the block every time.
With the right combination of parts, i dont see why there would be any issues. I've been running a 402 stroker with many miles and track passes for years, no issues at all. Lunati rods and crank, wiseco pistons.
Since we are essentially talking about piston rock at BDC (the main cause of oil burn and excessive wear/tear in a stroker), now might be a good time to discuss piston compression height. I have found a couple different compression height pistons on Summit's website. They range from 1.115" - 1.105". The shorter compression height moves the wrist pin "up" (closer to the top) of the piston. Assuming you have identical total height pistons, it would seem that the one with the shorter compression height would also expose more of the skirt at BDC. So, in a stroker application, would it not be better to have a higher compression height? I know the compression height also helps to determine the overall deck height. Let's assume that you can mill the block deck to achieve a zero deck with either piston (compression height). Wouldn't the longer compression height piston be the better option? Or does the piston taper have more influence on piston rock at BDC?
04-30-2024, 12:36 AM
To stroke or not to stroke ? Lq4 
