CubanGT

iTrader: (3)

So I need to pull the motor out of the car, and weighing my options on the rebuild. I don't want to spend a fortune, I already had the stock heads checked, cleaned and valve job done along with upgrading to double springs for the new cam I had bought.

I want to rebuild the motor to handle in the 500hp+ range(more if possible or running 100/150 shot later on)

but I guess what im wondering is a 347 short block better than rebuilding the stock motor with piston upgrade? Can I just have the stock block machined and upgrade the pistons.

I don't want to waste money going a route I cant use what I already bought and have done.

If I could get a 347 shortblock, would I be able to slap on my stock heads?
If I could get a 383 shortblock, would I be able to slap on my stock heads?

Can I have the stock motor just bored over a bit, use my heads and still get in the 500hp range?

svede1212

iTrader: (3)

It would be difficult to hit 500 RWHP without max effort on every part with a 347 (best heads, cam, everything) . It would be much easier with a stroker. There would be no advantage getting a 347 short block over refreshing your current one except a quicker turn around. BTW you can't bore out a LS1 very much. The absolute maximum I've ever seen is .010". My stroker is bored out .005". The added cubes are just about all in the stroke. I faced a similar thing when my Lunati Street lifters took out my engine. I was torn between getting a used 6.0 block or fixing mine. It ended up saving me about $1,000 going the route I did over a LQ9 stroker. To me that's a lot of money. I could have just refreshed and saved $1,800 or so more but I just couldn't see doing all the work to just get back to where I was.

HCI2000SS

iTrader: (2)

First I'd think about how much you'd like to spend, then go from there

CubanGT

iTrader: (3)

Well I def don't want to spend $8k right off the bat, but this is going to be our daily/toy to have fun in, we have our actual daily drivers.

So in the long run who knows how much we will spend on the car/motor. But basically I want to build the foundation while its out that I can later do bolt-on's that will get me close to the 500hp range..

If I understood correctly the rebuild of the stock block with better internals is not the route to go? or is it the other way around?

KCS

iTrader: (20)

It would be easier to hit 500whp with 383ci versus just 347ci. The extra cubes will allow you to use larger cylinder heads and a larger cam without sacrificing the street manners.

CubanGT

iTrader: (3)

ok, so would it be possible to build the 383 from the stock block? and if I did want to go that route, will I be able to use my stock heads with the upgrades I already did to them?

KCS

iTrader: (20)

Yes. You would need a 4" stroke crank, 6.125" length connecting rods, and pistons designed for the 4" stroke crank and 3.90x" bore. Yes, your heads will work too.

itsslow98

iTrader: (18)

If you plan on just having a stock head/mild cam and nitrous on top just do forged pistons/rods in the stock motor. You wont make 500rwhp with either combo(346/383) on stock heads. If your future plan is to add heads, bigger cam, bigger stall then do the 383 but know you probably wont be able to use the cam you have currently and the stock heads/intake manifold are going to be very restrictive. Not to mention you'll need some sort of aftermarket intake manifold.

All of the parts to make a 383 work well will add up in supporting mods(intake manifold, better heads, different cam, fuel injectors etc.)

HCI2000SS

iTrader: (2)

Yes you could stroke the stock LS1 to a 383 and run the stock heads, but you won't make any more power really. Another alternative is to go with a 6.0 iron block. That's what I did when I blew my LS1

CubanGT

iTrader: (3)

Well, I already have a moderate size cam I bought, not aggressive, but close. Got the double spring setup on the stock heads. Already have a Circle D 3000 stall installed, LS6 intake and long tube headers with hi-flow cats.

I don't have the specs with me, but can post them up later on the components I already have in hand. Just looking at what can be done to the stock block to get the most out of it without having to start from scratch on the build.

500hp may be unrealistic, but we def want to get all we can out of what we have without breaking the bank. If head swap is needed later one to help get more out of the motor, that's fine, I just want to build the lower end now to allow for future upgrades and swaps..

CubanGT

iTrader: (3)

So here is what I already have in hand for the motor build.
The heads like I said are the only things done on the build.

Cloyes LS1/LS2-1x/LS6 Race Billet True Roller Single Roller Timing Set, Includes Z06 Chain & 3 Keyway Sprocket, 3-Bolt Cam

Melling High Pressure Oil Pump, 1997+ LSx Based Vehicles

Powerbond 25% Underdrive Crankshaft Pulley, 1998-2002 LS1 F-Body, 2004+ Pontiac GTO

AC Belt for UD Crankshaft Pulley, 1998-2002 LS1 F-Body

Main belt for 98-02 F-Body w/ UD Pulley

Texas Speed & Performance 224/228 Camshaft: 224/228, .581'/.588', 112 LSA

Texas Speed & Performance 7.40 Chromemoly Pushrod, Per Pushrod

PRC .650" Dual Spring Kit

PRC Titanium Retainer for PRC Dual Spring, Single

PRC .650" Dual Valve Spring

PEP Spring Seat 1.250"od x .655 x .505id x .060

PRC Valve Seal Used with .650", .675" and .700" Lift Spring Kits

Texas Speed & Performance Camshaft Gasket & Bolt Package

KCS

iTrader: (20)

Food for thought:

383 Engine Dyno Results (graphs included)

CubanGT

iTrader: (3)

Well after reading some of my many posts and emails to sponsors for pricing on parts, it seems our original expectation on hp was actually to get close to or into the 400hp range with this rebuild.

if a 383 build is possible then im all for it
I've emailed a few of the recommended sponsors to get prices on a rebuild / core swap and will go from there..

My biggest dilemma right now is finding a build that I can take advantage of all the new parts I already bought and have, not looking to go a different route yet and have to start over and then find someone to buy all these parts..

I mean when the block was going to come out, plans were to upgrade the crank, pistons and rods to help build the foundation for future bolt on upgrades.

Keep the suggestions and ideas coming as I haven't made up my mind yet..

thanks

redbird555

iTrader: (14)

going to a stroker will cost more than just the price of the shortblock. as was said previously the stock head are going to choke the 383 out pretty terrible. My advice is if you stay with the 347 motor go pick up a set of 243 heads for 400 bucks mill them down .020-.030 and go with a .040 gasket. That will get quench and compression up and combined with the cam you will have a solid 410ish whp car.

If you are dead set on going with the 383. You can use all your parts except the cam and again the heads. In this case you'll have to experiment with head choices. The cam there is pretty mild even for an ls1 so that will have to be redone for a stroker cam as well as at a minimum a set of ported 243 heads.

On a side note. Unless you plan on boost you can go with stock parts. Rods arent too expensive and the crank honestly has been taken to 1000hp. The last thing I would replace is the crank. The rods are ok but if you feel the need they can be had pretty cheap. The pistons are the first and probably only thing I would really upgrade if I were doing a light bore job and not planning boost or HUGE power