99 Black Bird T/A

iTrader: (4)

Please Advise - 346 tore down…Need Advice…Rebuild as 347 or 383?

Background – bought a “good” 26K mile LS1 from another member that had been sitting for a little while. Motor failed leak down (42 #1 & 35 #3) & oil pan was tapped for F/I (I didn’t see the fitting). I took my chances with a used motor that had sat and that's what I got. I wanted to re-ring and go. WAR – Wegner Automotive Research – south is tearing down the motor to see what we have to work with. Bearings look like they have ~26K miles on them. The rings look worse but that may be from sitting. Cylinder walls looked good, as does the rest of the motor. Discovered one stock piston had been replaced with a Federal Mogul piston. Seller never mentioned that little detail.

Application – Motor will go in my 3rd Gen 91 RS after being flogged on an engine dyno for testing various parts i.e. cams, intakes, etc. Car will see some track time ~ five times a year or so but will be mostly a street car as my daily driver.

WAR suggested at least replacing the pistons and ideally the rods since we are going to flog the motor as dyno test mule. I trust WAR so I know should do pistons & rods. I have a 4-inch Callie’s crank I was planning to use in a LSx motor for my 72 Vette later on. With all the stuff the RS’s LS1 needs should I go ahead and use the Callies crank instead of rebuilding with a stock crank? What’s the smart thing to do?

Original Plan - was 346/347 w/ TEA LS6 2.5 heads, MMS 229v2.1 cam, 1 ¾ custom headers for 3rd Gen w/LS1, LS6 intake & ported TB w/28 pound injectors. Spray a small wet shot if needed for more power later on and keep the 28-pound injectors. Have 3200 Yank & 3.73 rear.

The RS will have a Walbro GS340 but I only have a set of 28-pound injectors. I have a MMS229v2.1 cam I was probably going to use if the motor was a 346. I have an LS6 intake and ported Jantzer 75mm TB on the way. Stepping up to the stroker and getting different cam will not leave me with the funds to do a LSX/90mm intake/TB setup if I want to finish the car this year.

Going Forward - Cost is almost a wash for building the engine. The 383 will cost a little more for clearancing block & and few bucks to balance. I’m concerned about the supporting parts I have if I go with a 383.

May need bigger injectors for 383?
Probably should get a different i.e. bigger cam for the 383?
LS6 intake will be restrictive for the 383?
Ported stock TB will be restrictive for the 383?
Custom 1 ¾ headers being built might be too small for 383?
Will tuning a 383 being more difficult or risky than a 346?

I need opinions on the wise course of action.

Thank you for taking time to read and provide suggestions.

Wade

Mike K.

383 will be more fun thats for sure but the 346 is more practical. Yes you could use the bigger headers but the 1 3/4 will work. Tuning should be the same I'd imagine, Yes a bigger cam for better power will be needed, I think everybody is using the ls6 intake and ported TB on their stroker setups so you'll be ok there as well. Yes you'll need bigger injectors also.

Wise course of action is to stay with the 346.

Satisfying course of action is get the stroker.

CAT3

iTrader: (9)

Are you sure the injectors are 28.8#'s, or could they be a seller "deal" as well and be 99-00 26.2#'s? That would suck a little more?
Bigger cam, should for a stroker if you want to make the extra power even more so.
LS6 Intake will be fine, hasnt seemed to restrict to many others.
You could port the TB, get a ported one, or use it stock, just make sure the blade opens all the way!
Tuning shouldnt be any worse for a stroker than stock cubes, its getting the cam down thats a PITA.
Good luck. FWIW, I would stay stock forged cubes and continue the Callies where you started!

99 Black Bird T/A

iTrader: (4)

I picked up the injectors from Cammin Beast, I'm sure they are 28.8#'s. If they were from the seller with my luck they'd be 24#'s or less.

CAT3

iTrader: (9)

Ok, just checking.

DenzSS

Nope. You'll be fine.

I wouldn't. It is a daily driver. You're looking for reliability as well as performance.
Keep the cam as reasonable as possible. Keep the ramp rate and lift to a reasonable level.

Not really. The LS6 will work just fine.

Nope. It will do just fine.

Nope. Street car. They will do just fine.

Not in the slightest. Nothing odd at all about tuning a 383.


In short. It is a street car and a daily driver. The extra stroke will make it a lot of fun and make a good deal of extra torque. The lower in your range you can make torque, the better your fuel economy will be. Another important aspect in a daily driver.

SAM98WS6

Im building a 383 Callies forged stroker right now..what I did follows..
You need bigger injectors...I went with SLP flow matched 36#..tuning
Fuel pump a must- Racetronix
LSX 90mm Intake and TB
Kooks 1 7/8 headers
Cams cost the same..242/250 .595/.595 109

as soon as i get the TB that has been on backorder for a month I will fire it up.

DenzSS

None of those are requirements in any way. Upgrading your fuel system isn't a bad idea, but it isn't a requirement. Intake, TB, and 1 7/8" headers are also in no way a requirement.

Linear Velocity

iTrader: (1)

I would stay with the 347 for many reasons. Toruqe on the street is fun, but only to an extent. The amount of torque I had in the 388 was almost unusuable on the street, even with drag radials and a good suspension. I don't agree that a 383 will give you better gas mileage, bigger cube motors will always have worse gas mileage. So in short save the crank for something else and build a 347.

DenzSS

Sorry, but incorrect. The BSFC is the inverse of the torque curve.

I also have a problem saying something has too much torque. There are a LOT of street cars that have hundreds of ft-lb of torque on a 383 LS1.

That is a matter of driving, suspension, and tires.

Jagrmaister

I'd say build a hell of a 347 and ready it for forced induction. But that's me...

You know what's right for you in the end. Either way, you're probably going to end up happy with the results. Good modding to you.

Scalpel

iTrader: (4)

I agree with the too much torque. Mine has so much useless street TQ.

However, I do get 24 MPG on the highway

99 Black Bird T/A

iTrader: (4)

Didn't think about the low end torque might be very hard to hook up. There are some excellent points being made and I appreciated that very much.

DenzSS

I know guys that hook with 500+ cubic in big blocks. There's always a way.

99 Black Bird T/A

iTrader: (4)

Suspension wise this is what I've got on or for the RS, SLP RLCA's & Panhard probably new springs & shocks, TGR's torque arm for the LS1 swap, air bags & lower control arm brackets, 10-bolt w/Auburn & 3.73's & Drag Radials on 10 spoke SS 17's

Nothing fancy.

Car should weight ~ 3150 or maybe a little less depending on what else I chuck out of the car w/o driver

I think the 347 would work well with that more or less on the street. Will the 383 be too much?

BTW - I'm not really up on stroker stuff as the Vette's engine project is a long range plan.

DenzSS

Nope. Not too much. Otherwise, why would I have a 408 and a bunch of other folks have 427+ engines in street cars.

CHRISPY

Which project car are you planning to drive more? I would go 383 personally. You'll get an additional 30-40RWHP and RWTQ depending on cam/exhaust etc etc.

Would be a lot of fun!

PREDATOR-Z

Is it an A4 or a 5/6 speed??
If it were me, I would go forged high revving 347 with a standard trans and 383 with auto. But that's just me.

99 Black Bird T/A

iTrader: (4)

I'll probably drive the RS the most. The RS has averaged 19,000+ miles a year since I bought the RS in 1991. The T/A ~8,500 miles a year. Yes, I drive a lot. So ~ 27,000 miles a year split between the cars.

The RS will stay an A4

StevieZ

iTrader: (3)

Definitely go with a bigger cam if you go with the stroker. Extra cubes have a way of taming a cam. I just went from a 232/232@50 w/.575 lift to a 242/242@50 w.612lift. with my stroker.