Ive decided to build a very mild turbo engine. It will be so insignificant as apossed to most that many will say "why?". So first I'll say,"to learn and have fun". The set up will be a 5.3 lm7 with re worked stock head/aftermarket heads. I won't know more untll I pick up my core. I had recently been burned by a second party sell and this time the core goes from my truck to the machine shop. Many will say why but truth is I want it done and not worry about losing a rod or valve because of a little money. So my goals are very small, 400 rwhp and the tourqe to go with it. Safe, semi relisble, manageable and updatable in the future. I will re use parts worth re using snd buy upgraded parts within resson. So my questions are for my knowledge and so I can make sure my machine shop has a clear guideline to follow. Are there specific tolerances that are specific to boosted motors? Main bearings ? Rod bearings? Piston to wall? Different piston pins/tolerances? Rings/gaps? What are some general guidelines to static compression? Stock ok or lower for longevity? Again iam doing this because I want to learn and know it's built right. I will either send out the heads or buy tps heads. I have asked a turbo shop to help organize those parts for me with these goals in mind. I would like to be informed when I drop this engine off at the machine shop. I would also be interested in name brands that you trust for internal parts. Ie-federal mogul vs clevlite ect.. The unknown is where the cylinders will clean up and if a forged piston and different compression ratio will be used. Lots of questions with many variables I know but this is really fun to me and I want to learn. Thanks for your insights in advance.

 

For 4-450hp, there is absolutely no reason to even take an engine to a machine shop. You will be wasting money. Buy a good running used engine and bolt it in, put a turbo system on it and run it! Completely stock motors will reliably handle a fair bit of power. The 6L in my truck has nothing more than a cam and head studs and had made as much as 800rwhp and daily drives on 600 for the last 5 years.

 

What Kyle said.

Buy an engine as complete as you can get it, drop it in and put a turbo on it.
400HP is such a laughable goal you'll probably make much more than that by accident.

 

As far as clearances go, you can go by the OEM tolerances since you're not looking for that much power.

https://ls1tech.com/forums/generatio...learances.html

As you increase the power, you want to increase the clearances. A general rule of thumb is .001" of clearance for every 1" of shaft diameter in a performance engine; which applies to the main, rod, and cam bearings as well as the pin bores in the rods and pistons. The piston ring manufacturers include recommended ring gaps with the rings, but they usually start at about .004" of gap per 1" of bore diameter. Looser bearing clearances will lower the oil pressure and larger rings gaps will increase blow by, so you don't want to use the looser clearances if you don't need them.

I haven't had very good luck honing a block and not needing new oversized pistons. If you just ball hone the cylinders for a fresh crosshatch, you might be ok, but in a professional shop where they have a real hone, like a Sunnen CK10, then you might as well have it torque plate honed and get new pistons.

 

400 wheel gonna need a LSX block or a billet block. The amount of money and boost you are going to have in this thing take make that kibd of power you should just talk to Proline or BAE.

 

Thanks for your humor, couldn't see that coming. Lucky I have these forums to set me straight. Guess I'll just pull a **** house motor out of a ******* 20 year suburban and make rod soup cause iam 16 and it's fun to get greasy!? I remember when you had to spend 15 grand to go really fast. I have a stupid friend who spent 40k to go 119mph at Bonneville, wtf ? It's only for fun and iam ******* rich.

 

There isn't any fun in giving it to a machine shop to do your work.

 

I doubt many here have machine shops? But I won't argue about it. I thought it was a readonsble post and i was honest sbout it bieng unessacary to build a big money engine . I really do love engines but iam a amateur at best. Thanks for answering my questions and look forward to having a more productive conversation another time. Maybe some day I could actually contribute to it. I can't figure out how to delete this post so if you are a moderator please feel free to do so. Regards Charlie

 

Good book. I use it for reference all the time. There are a few more books that are a good read also.

 

I don't know why you are getting so upset, my response was quite accurate. These aren't the old small blocks of yesteryear. The gen 3 and 4 LS motor are very strong in complete stock form. Do a little more research. Many many times, a stock motor has handled quite a bit more then your goals. If you want to build a forged, blueprinted motor for your very low goals, then please feel free. I was just telling you it's quite unnecessary.

 

IIRC the OP just got burned on a JY motor deal and its probably still sore about it.

I have that book sbcgenII linked up there and it's pretty useful, if just for having torque specs at hand without getting your phone greasy.

 

my ready to run low mile pull out engine complete with two cracked heads and spun main. bad day at work and old and grumpy

 

The motor that you get back from the machine shop with those TPS heads will make your HP goals without a turbo with the right parts. If you truly wanna learn how to build a good foundation I say build it NA and take notes then slap a turbo on it later.

 

good advice thanks. I ordered several books and will keep on learning. I only wanted good part and iam having more trouble than it's worth sourcing them. I don't want big valves and flowed heads and a over cammed engine really. Just get sucked in and like to fabricate tubing for some reason. Making headers and roll cages is fun to me .my welder is dusty and hasent been used in awhile I honestly think I, or worse , someone else would get hurt if this car had more than 400 rwhp.

 

Go NA then and a somewhat mild cam should get you to where you wanna be. These LS based motors can make some power. Be warned power is addicting. You will want more sooner than later.

And nice sled you've got there.

 

Check out Blake Hughes (417 Motorsports) facebook page, there's a video of his truck from this past weekend. 1067whp on a superflow dyno. bone stock pieced together gen 4 aluminum 5.3 except arp heads studs, LJMS stage 2 turbo cam kit, shortened hi-ram and 417 intercooler. stock to using used rings and bearings out of 3 different engines and my 19 year old son Andrew honed it with a flex hone and assembled it. Forced Inductions billet S400 85mm.

 

Oh gapped the rings to like .024"-.028", might be a couple at .060"