I want to put a 383 in my 6 spd 05 GTO. Its my daily driver and I'm looking for around 450whp with as much torque as I can get. I want a stockish redline and probably around 11.0:1 SCR. I've "overhauled" a few other engines, BMW and Triumph, and I did my cam swap in my old SS, but I've not done anything this in depth. So far I've got an LS1 torn down to the bare block so its actually time to start buying crap. Its a 200k mile motor. A piston actually fell out and hit me in the leg. I'm planning to use:

LS1 block with 3.905 bore
TSP rotating assembly with Callies LSc crank, TSP H beam rods, and Weisco 3.903 -3cc flat tops, ARP 2000 bolts.
Clevite H main and rod bearings
Cam TBD by Tick with BTR dual springs and appr PRs
Stock timing gears with LS2 chain
Melling oil pump
Stock LS2 intake manifold with p&p LS2 tb
LS3 injectors with whatever spacers are necessary
Pace Setter 1 3/4 headers with catless stock exhaust.
MLS head gaskets
stock fuel pump
Probably ARP head bolts unless I find some good used studs, reusing stock main cap bolts and everything else, I think.


Heads are still up in the air. I have a set of 241s laying around, and I have 243s on my car now. I have a few options in my price range. Most expensive to least: PRC Stg 1.0 LS6 heads, TEA Stg 1 LS1 heads, or just buy a set of 799/243 and clean them up. I know I have to match the pistons to the head to set everything up right, and it would probably be best to pick the head first.

What do I need to do with the knock sensors? Cam sensor? Can I plug the harness into an LS1 cam sensor or do I need to run the whole LS2 timing set and front cover?

I know it seems like a crime to put a car together without a FAST intake these days, but its not worth a grand to me; not on this build. How does it sound other than that? Anything wildly inappropriate? Recommendations for bearing clearances? I want to do as much of this myself if I can. I'm going to take the old LS1 components over to the machine shop and ask them to run me through wtf I'm looking at as far as wear and bearing surfaces goes. Hopefully my machinist will let me hang around for preassembly so I can learn a little more. Its not rocket science, but I needs some guidance. So tell me what you think and help with head/piston choice.

 

cmon now

 

I would go with a set of 1 7/8 stainless headers if you can afford it. I had uncoated pacesetter and they got ugly pretty quick.

-Trunion upgrade on stock rockers
-I would buy new Main Bolts, I believe OEM are TTY and shouldn't be reused
-Since you have a set of 243's, I'd get them reworked. I had an awesome set of TEA243's
-Be sure to double the amount of $$ that you think your gonna spend.....I wish I would have

 

I'm strongly considering the trunion upgrade, but I might not do it at the same time. Everything I've read about the main bolts says they aren't really TTY, but they can wear out with repeated torquing, so IDK. I don't think this motor has been opened before. Martin at Tick has recommended sending my 241's to TEA. I could use the 243s, but I will be running that motor until the day I do the swap. Yeah, it all adds up quick.

 

I think, if you will do some checking, the 3.903 pistons are made for a 3.903 bore, not a 3.905.

 

Yeah, I had noticed that. You buy pistons labeled as the same size as the bore because they are actually undersized by a specified amount set by the manufacturer, correct? So should I have the block machined first to see what it will take to get straight bores?

 

Get the pistons first and let the machine shop hone the block out to fit then for the clearance you want.

 

If it is an 05 don't you have a LS2? I am probably in the minority but I agree with you about the fast intake.

 

In for information on 383 build.

 

why not just build the ls2, friend has a rx7 with an ls2 put down a little over 450 at the wheels, it might be just me, but I'm going to spend the money stroking a motor might as well squeeze every hp out the motor with good heads, intake and exhaust. but I do like the sound of a stroker, made 481rwhp with mine, can maybe squeeze some more with the tune but I like it safe and the nitrous makes up for the hp left on the tune

 

I completely understand the urgings to stroke the LS2 I have. I'm not saying I won't. I'm saying I'm choosing not to right now because:

This is my DD and I don't want the down time while building it.
I want to build most of it myself, and I can't do that if Ii have to rush to get the car back together.
A 402 in this car is an even bigger waste than the 383 for the power I'm looking for.
I might put it in my corvette.
I might sell it outright and go for a 427 in my corvette.

I'm not even close to trying to squeeze the most power I can out of the 383. My goal is my goal. I want about 450hp and as much low end grunt as I can get. Its not a max power thing at all. I understand that's not efficient. I understand I could just do heads and cam on my LS2, but then I would have a 125k mile H/C car instead of a new stroker car. Its somewhat unorthodox, but I have my reasons for choosing this path.

 

If all you're after is low end grunt, and don't care about much of anything after 6300ish, then just drop in the Eagle 393/395 kit and be done with it.

That would surpass your goals and give you pretty stupid torque down low.

 

No doubt. However, I've heard a lot of **** about Eagle cranks from people, including my machinist. I'm not sure how confident I am with more than a 4in stroke on a stock block either.

 

I wouldn't be. At all.

Hell, I bought this guys crank. Used. And it looked PERFECT when I received it.

http://www.ls1tech.com/forums/showth...594&styleid=27

I'd definitely contact Brian Nutter at Wiseco to get the appropriate piston to accommodate the 4.1" stroke.

 

I'm just throwing it out there but why not keep the stock crank, sell the ls2 intake, and put the money toward a better set of heads and a fast intake? 450 is very doable on 347 cubes and with a better flowing set of heads and intake you can get to that 450 horsepower number with a smaller camshaft that will have killer midrange torque.

 

i stopped reading at "this is my DD"

rule 1: don't mod your DD

on a more serious note:

CNC'd 241's on a healthy cam should get you around or slightly more than 450hp at the tire...built and assembled properly with ALL supporting mods. that is on 347cid.

a 383 kit is really an unneeded expense unless you GOTTA have a "383"...or a "396" or whatever...

you WILL need upgraded rockers with the spring pressures you'll be running to support the cam required to get to that HP goal. don't half *** this part...or ANY part of your valvetrain...

 

I am with the guys saying "why bother stroking it?"

Power comes from airflow, 100% of which has to pass through the topend to get to the bottomend and then needs to leave through it after the power stroke. As such the best bang for the buck i to start modding the topend.
You might add 100hp with a good set of ported heads and cam but only another 20-30hp with the stroker shortblock with that same heads and cam yet they cost similar amounts, to get the stroker to shine more means giving it larger heads and cam that it can support with the extra displacement but it still wont compare to the bang for the buck you get with the initial heads and cam on stock shortblock.

Keeping rpm low it might be a little challenging to hit your full goal BUT I also suspect you don't really know what 450rwhp is. That is enough to make you have to put a rollbar in the car if you launch well at the dragstrip, it is enough to break decent street tires loose momentarily at 45mph on dry roads.

I say those thing based on having a maybe 420rwhp(never dyno'd based on performance) car that has a raceweight between 41-4200lbs and has runs 11.5 in the quarter. The pedal goes to the floor a lot less often now than it did at lower performance levels, not a lot of opportunity to USE that kind of power.

Not saying don't mod it just trying to say you can save a LOT by understanding just what you are looking at performance wise and maybe scaling back expectations slightly.

 

My vette puts 600 to the wheels. I know what I'm asking for. I know those goals are easy enough with a h/c/i LS2, but I'd rather have a new motor. On a rebuilt LS2 I thinkI would be fine. Yeah, you can do it with a 347, but I seriously doubt it would have the characteristics I want at that power level, and it really wouldn't save much over a forged rebuild. My camaro was right at 400whp and it did about 370-380 ft/lbs I think. With 4.11s it still needed more torque in a car that weighed a good bit less. That was with a sleeper cam. With awesome heads it probably could have done about 440hp, but the torque would never be what I want. Its not about huge power, its about a bunch of torque with a stockish powerband and easy drivabilty. If GM had offerd a 450rwtq production 383, that is what I am after.

 

I think you're making the right choice with a stroker. Ported heads and aftermarket cams won't do as much for torque as the extra displacement will. A 383ci LS1 should easily put you close to 450ft-lbs really early in the RPM range and as much as 500ft-lbs with a good combination of parts.

 

Yeah, that's what I'm hoping for, as long as I put it together right.