Machine work, need suggestions, turbo lq4
12-27-2012, 02:57 AM
#1
Machine work, need suggestions, turbo lq4 I'm piecing together an turbo LQ4 build. When I get a used motor, say around 100k miles, what should I do machine work wise, or would you just drop it in and go? Main question is the cam bearings. When is it good to replace those or do you have to. I've heard of guys filing down the ring gap. Could I just buy rings gapped less if I'm going to buy new ones anyways? Bore or hone? Can you replace the crank and rod bearings without machining either?
Any info you guys will help and help decide what I need to start buying. I'd like to make 500-600rwhp without having to forge. But if I must, I must.
And either way I will be replacing timing set, cam, springs, valve stem seals, push rods, and all gaskets including head.
Any info you guys will help and help decide what I need to start buying. I'd like to make 500-600rwhp without having to forge. But if I must, I must.
And either way I will be replacing timing set, cam, springs, valve stem seals, push rods, and all gaskets including head.
12-27-2012, 05:26 AM
#2
If it was my car I would definitely go through the motor. I'll break it down into a couple steps. If the motor is going to be built I like do cam bearings if it’s the first time it comes apart. Although not always needed I like to just I am picky.
The ring situation really depends on what the engine will be used for more street use or strictly drag use. You will have to determine that and talk with your machinist. I don't have experience using gapless rings so maybe someone else can chime in to provide more info. What you do want to look out for is if you’re running a higher boost application you generally want to run a slightly looser ring gap because the boost can cause the ring to get to expanded and cause some damage and it can break ring lands etc.
Boring and honing are two different things. Honing is simply to get a good crosshatch on the cylinder wall and to remove very very minor imperfections but it will not correct of out of round etc. Boring cuts material from the cylinder walls to correct and out of round, tapered cylinders etc. Honing is done after the boring to finish up the surface. Depending on how cylinder walls are you may just be able to get away with a good hone job to get a good crosshatch surface on the walls.
As far as the bearings go you need to check out the journals on the crank for the rod bearings, if they pass specification for out of round, taper, and aren’t obviously scored or damaged then you can pass on machining although I like a good polish on the journals. The mains have to be machined after hearing your goal of 500-600 hp. Just a personal opinion on that but that’s what I would do. You technically can put new main bearings in if the mains pass for out of round, taper etc. Your going to be doing allot of measuring and re-measuring.
One more thing I would have done is the block to be decked if the head mounting surface is not perfect, especially on a boosted application.
Last thing, if it was my car I would definitely get a forged rotating assembly, at least rods and pistons. The cranks are strong and there are tons making over the power goals you are asking.
Some people will disagree with what I say but this is they way I would do it. I hope I helped you out in someway. Good luck and have fun sounds like a great project.
The ring situation really depends on what the engine will be used for more street use or strictly drag use. You will have to determine that and talk with your machinist. I don't have experience using gapless rings so maybe someone else can chime in to provide more info. What you do want to look out for is if you’re running a higher boost application you generally want to run a slightly looser ring gap because the boost can cause the ring to get to expanded and cause some damage and it can break ring lands etc.
Boring and honing are two different things. Honing is simply to get a good crosshatch on the cylinder wall and to remove very very minor imperfections but it will not correct of out of round etc. Boring cuts material from the cylinder walls to correct and out of round, tapered cylinders etc. Honing is done after the boring to finish up the surface. Depending on how cylinder walls are you may just be able to get away with a good hone job to get a good crosshatch surface on the walls.
As far as the bearings go you need to check out the journals on the crank for the rod bearings, if they pass specification for out of round, taper, and aren’t obviously scored or damaged then you can pass on machining although I like a good polish on the journals. The mains have to be machined after hearing your goal of 500-600 hp. Just a personal opinion on that but that’s what I would do. You technically can put new main bearings in if the mains pass for out of round, taper etc. Your going to be doing allot of measuring and re-measuring.
One more thing I would have done is the block to be decked if the head mounting surface is not perfect, especially on a boosted application.
Last thing, if it was my car I would definitely get a forged rotating assembly, at least rods and pistons. The cranks are strong and there are tons making over the power goals you are asking.
Some people will disagree with what I say but this is they way I would do it. I hope I helped you out in someway. Good luck and have fun sounds like a great project.
12-27-2012, 11:15 AM
#3
Thanks, you did help. With the rings I dont mean going gapless. I've seen on thread people are filing the gap on old stock rings down another .010 or .030. Just wondering if I can buy rings that just already have a larger gap so no filing is required since I'm buying new anyways.
What tool would measure the rod and crank journals, a micrometer I would imagine?
Say I just do a hone. Is that something I could do myself or a machine shop has to? I've seen the kits that attach to drills at autozone but I dont know if they're worth anything and would work. After the hone would I buy stock size pistons?
The reason I dont want to forge yet is because I want to do the swap and getting running on a little boost to start. If I ever do go forged I would just buy a shortblock already built for the extra peace of mind not having to trust myself.
What tool would measure the rod and crank journals, a micrometer I would imagine?
Say I just do a hone. Is that something I could do myself or a machine shop has to? I've seen the kits that attach to drills at autozone but I dont know if they're worth anything and would work. After the hone would I buy stock size pistons?
The reason I dont want to forge yet is because I want to do the swap and getting running on a little boost to start. If I ever do go forged I would just buy a shortblock already built for the extra peace of mind not having to trust myself.
12-27-2012, 05:01 PM
#4
You can buy new stock rings and file them down, or you can get file fit rings which would be my choice. To measure the crank you would need a micrometer. For cylinders and main bearing bores you can either use a t-gauge with a micrometer or a dial bore gauge. You can get use the ball hone that goes on the drill. I've used them in the past as long as you take your time and make sure the crosshatch is good then you can use them. Only if you see major problems with the walls I would go to a machine shop. A hone should not take enough material out of the bore to require a new sized pistons but still go slow and double check every now and then to make sure your don't doing.
