Looking for some thoughts from the masses. I have an 89 GTA with a Procharged 383. I am currently getting ready to drop the motor/T56 to fix some oil leaks. I keep going back to swapping in a 5.3/6.0. I have a 383 with GM fast burn heads, Scat crank, eagle rods/pistons, unknown cam, Edelbrock lower intake with SLP runners and BBK throttle body. This combo with the Procharger made 401 hp on the dyno. I am already running a terminator X ECU and the dual sync is giving me fits and upon reading I am questioning the reliability of it. I really want a nice car show cruiser. I think I can get more power out of NA 6.0 with a cam and tuning or maybe not. I struggle with keeping things period correct, but the TPI is an old platform and if I need parts I am ordering them. The whine of the supercharger is great and when it was running it was great.
I could possibly sell the engine, Procharger, wiring harness and offset some of the cost of the swap, just keeping the Terminator X and buy a new correct harness. What are the thoughts of the masses?

Your set-up seems really stout but you could easily replicate that 400 rwhp with a mild 6.0. However, you have to change the trans along with all the other parts required for an LS swap. Might not be worth the effort since you have a running combo right now. Granted you could sell off parts to recoup some funds but it won't likely cover everything you need. You could also go straight to a GM ECM since you won't require any exotic ECU. Tough call.

Likely so.

Also likely.

Not sure what would need to be done re. the T-56. I guess that would depend greatly on which T-56 it is and how it's installed now, particularly the clutch setup.
​​​​​​​

I was hoping to use the t56 I was assuming I would just have to replace the clutch/flywheel to match the engine.

​​​​​​​Oh I see...

Looks like I would need the bellhousing, input shaft and new clutch/flywheel to convert my LT1 t56 to LS t56.

Yes. It would be easier to sell yours and buy an LS style.

It depends what you're looking for, but given what you already have and the work involved, I wouldn't do it.

If the dual sync is giving you fits (they always do), you can switch to coil on plug. I think the Terminator will run that as long as you can get it a crank signal.

Indeed. And depending on the shape yours is in, you might even be able to do that at a profit, since there were VASTLY more LS T-56s visited upon the world in the first place than LT1 ones (if that's what yours is), and the LT1 ones, being older, are becoming even scarcer especially in good condition.

If I were sitting where you are-keep what you have/as above coil on plug/change out the cam to a known spec that's got healthy specs,/bigger heads/and especially change the intake to miniram stealthram etc.Then reasses how much boost you can feed it after the new head compression ratio is calced.

If I was going to go through all the effort of an LS swap then I'd want to be blown away by how much better it is and I don't think that's going to happen in this case without thinking bigger and better. You can do a warmed over 6.0L if you're okay with a sideways move. You'll be disappointed with a cam only 5.3.

If you just got rid of that TPI intake then you might make a lot more power with your 383.

Yeah, I was thinking, loose the TPI. You're at the limit of power it can make. A 383 w a blower should be putting out more power. Using an intake that flows letter up high will make a massive difference. I have a pro flo XT and it makes power up to 6k without issue. Im sure there are other ls style intakes that you can use as well. I know Holley just came out w one also. Yeah, a built LS will make great power. If funds aren't an issue, go for it. While you're at it put the pro charger on that engine!!! But, I bet an intake swap +/- an EFI swap could be awesome, just not as awesome as a blown LS!

I'd stay 383, since you already have the Holley X on it, just upgrade the heads and intake with Cam, at 12 psi that should make well over 500 whp.
you say your dual sync is acting up??, did you change the dwell time from rising to falling??

I had the car tuned by a reputable shop, it ran great all summer, but went to start it 4 months ago and at idle and up to 2500 RPMS no issues, beyond 2500 it develops a miss and is very noticeable. Did the normal diagnostics, pulled plugs, changed plugs, wires, read cylinder temps, compression test, leak down test. No issues. all 8 cylinders read the same within +/- 1lb. Pulled the distributor cap and everything inside is rusted. I never drove the car in the rain, cause t-tops and I hate rust.

According to the tuner the current combo is maxed out, any more adjustments I would need to go to race fuel. I have 1 shop 60 miles away that is willing to tune "old cars" even with the Terminator X on it. If it was LS based than I have way more options. Even if I stayed with the holley.

That's interesting. Who is doing your tuning? There is also E85 available at a few stations in the Omaha area, for what it's worth.

The Shop Inc. was the only one that was willing and interested.

I've worked with a guy in Springfield. He's good and knows the Holley stuff. If you're interested, PM me and I'll share the details.

If you do decide to go with the LS, I'd be interested in the T56 and am local.

Thanks everyone for the input, this gives me some information to go through.

Rust??
I'd say there is moisture getting in from somewhere, either way you could put a dist boot on it like the ford used to help with moisture intrusions, you can always use Meth injection to aid in cooling with your current set up to gain extra Hp, or go with E 85.

How much boost?

something seems wrong, last basic procharged 383 tpi car i tuned with a tko 5 spd made 530 whp on 8 psi

it had afr 195 heads which i like alot but your combo seems down a lot of power

i dont like dual syncs. Heard issues with them. Id look at throwing on a crank trigger and 1x cam sync from efi connection, converting to coil pack ignition like an ls. Try that. If you wanna go ls later, its basically set up for it just extend the harness wires

I will never go back to small blocks. The LS fixed so many of their issues, its crazy to keep using one for any reason, nevermind performance.

A key to reliable LS swap is all factory engine parts as possible. Use a supercharger or turbo to make the power. I recommend 05' L33 as king of swap LS
Factory $3.00 ECU is higher quality than Holley, nobody will want to steal it and you can pile up engines and computers a dime a dozen for insurance

The LS swap isn't really a performance move. Its a control and accessibility move. You now have access to a reliable built-in sequential crank trigger ID and a factory tuned decoder. That is several thousands of dollars of aftermarket hardware and tweaking and setting up for the price of a cheeseburger. The L33 is a world recorder holder, **** runs sevens stock bottom end.

Thats a stock rod in an L33 I picked up. Full floating forged from the factory with a Gen3 411 harness which support 200lb/hr injector, flex, 3-bar, torque management, MLS headgasket, coil over plug


This is the stock 130k miles engine I just wiped pistons with a paper towel, no solvents

I am running 12lbs boost, I reached out to efi connection on the crank trigger and 1x cam sync to get the right one, but they never responded, just the automated email.

I think that your setup should make more power w 12 lbs of boost. I kind of wonder if the tpi is killing your power. I'm no engine guru but 400hp sounds low w your setup and boost.

I have always thought so, but I don't know the compression ratio. The previous owner can't find the build info on the motor because it was built in early 2000s.
I could go to Holley's new intake, slap on the LS throttle body I have in the cabinet, than go for a re-tune but the tuning session is $1000, so at that point I am pushing $2,000 for just an intake change. hence I am on the fence to just step into a newer powerplant.

I'm sure it will be more than 2k. It always is! Last intake swap I did turned into a cam and heads just cause I was there!

Most likely, since there are probably some cam improvements since 2003, not sure on heads as the fast burns are ok, are there better out there, yes.

I have fast burns on mine. I'm really happy w them. W flat tops they give 9.6 compression. I'm in the process of putting a blower on my zz430 clone with a pro flow XT. The tuner thinks it should be a 550-600hp combo. Mine should be all sent in 2-3 months.