L695speed

I've been looking at options for a motor since an oil pump failed or a bearing went bad in the LG4 (was a straight swap and the motor was free). I talked to the engine builder and he said that he could do a 350 Horse 350 for 2 grand, compared to doing the L69 for 1600 or so. Now, looking at the increase in power and the price difference I find it very tempting to go with the 350. However, what is stopping me is I am trying to find out whether my drivetrain will hold up or if it will self destruct. I'm not a drag racer so it will hold up reasonably well but I will admit to maybe a couple runs down the strip.

So if I go with the 350 HP 350 will I end up having to upgrade the trans and rear or will I be ok for a street car/occasional autocross drag strip runs? I've looked around and it seems like there is more involved with a T56 swap than just dropping the trans in. If I can avoid it I would prefer to hold off on the 6 speed swap. I've looked around and people are asking 2 grand for a used T56. sounds like BS in my opinion.

I would like to keep as much of the car stock as possible. I'm running the original T5 and 3.73 G80 rear. If that will hold up when driven reasonably most of the time then I'll keep it and go with the 350, but if I will end up having to upgrade the rear and the trans then I might just rebuild the L69.

Abubaca

iTrader: (3)

Unfortunately there's really no black and white answer.

Officially? No, it won't hold up. The non world class borg warner T5 trans and 7.5" 10 bolt rear are BOTH more than likely not gonna hold up.

....but....it all depends how you drive. Is it a daily driver? Can you afford the time and money to just do it, and see what happens? I've got a friend that road races a 396ci engine paired to a world class T5, and after 7 years he's just starting to see issues. You could swap in a borg warner 9 bolt rear for a few hundred bucks and it'd REALLY strengthen up the back end. EASILY the best bang for the buck for a car that see only a few 1320 passes. ...and you can swap it in a few hours.

Honestly, I think it boils down to whether or not it's your DD. Everyday driver, I say L96. If you've got another ride, I say go for the 350.

L695speed

Its not a daily driver. Has QQ historic plates on it. From what I've read and heard, its possible to make the original setup last if I don't drag race it and build up the T5. But if I do take it to the strip, it won't be every weekend. Thing about going the 350 route....I know first hand what 350+ HP does in a later Fbody, a friend has an 82 with a 406 that runs low-12s with wheel spin for the first 100 feet. And I've ridden in a 2002 Collectors Edition TA with SLP upgrades. Both cars are outrageously fast for the street. Thing is, I have the time, but not the money for the 6 speed swap. But at the same time I want to be able to put it back together original if I want to. Hence wanting to keep the 10 bolt and the T5.

IF I DO RACE, I'm more of a road racer than a drag racer. Strips can be fun but it gets boring going in a straight line for me all the time. This is going to be a street car more than a racer.

92RS_Ttop

iTrader: (3)

Id go for the 350. I'm running a V6 T5(World Class though) behind my 350 and I've had no problems so far although its only been about 6K miles since I built the 350 and dropped it in. I DD the car from May to November. I drive it hard, but don't abuse it. As long as you don't do stupid **** like dumping the clutch all the time, miss shifts, or powershift it should hold up. I also prefer road-course racing/autocross to straight-line performance. Although I've never actually autocrossed the car yet, I do love driving hard and fast on the twisty backroads in the mountains here in PA.

EDIT: I should mention I rebuilt the T5 at the same time as the 350. Just a basic stock rebuild, nothing fancy. I'm also still running the original 10-bolt drum rear with 3.42s in it. I have a disc rear from a 93 Trans Am along with 3.73s waiting to go in this winter though.

L695speed

Sounds like you will have a similar setup to what I might end up doing, assuming the disc rear is a 10 bolt and stock. I might rebuild the T5 to WC spec at least if not stronger. My Dad had the rear end in my car rebuilt in Oct of 93. So it has fewer miles on the rear than the car for sure. It sounds like some people have had luck sticking with the T5 and 10 bolt. Even the engine builder said hes had people stick with the T5s and had people who sold the T5s. I'm thinking maybe I'll stick with the T5, and build it up. Then if I have an issue after a few years I might have the money then to do a 6 speed swap or whatever I decide to do.

But from what everyone seems to be saying and your experience I'm guessing I might be fine as long as I don't drag race every weekend.

Abubaca

iTrader: (3)

OK, in your case, I'd totally go for the 350. ...and keep the T5. You get a lot of kids on here who save up to buy their first car, and the last thing I want to do is to suggest more power than could potentially blow up a tranny or rear end. If you're not dependant on it for everyday duty, then I think it's totally worth rolling the dice and seeing what happens. Keep in mind that the 9 bolt was original equipment on LOTS of later thirdgens. I bought my 3.27 geared posi/disc rear for about $275. Not exactly "stock" but it's not really frankenstein either. Up to you. Honestly that t5 will let go before the rear.

...as for the t5, I'm not sure the non world class can be rebuilt to world class specs. Maybe, but I don't think so. ....but there again, T5's are relatively cheap. I would never use the T5 as a replacement for the t56, but if it's what ya got now, then no need to spend the money on a t56. At worst, ya drive it for awhile, and then do the swap at a later date.

92RS_Ttop

iTrader: (3)

Keep the T5 till it dies or you have the $$ for a T56 swap.

Yes, the rear I'm swapping in is the same stock 10-bolt rear that is in the car now, except for the gearing and brakes. I welded the axle tubes to the housing and will buy or fab a stronger cover for it to help, but that's all just added insurance in case I ever let the wife drive it(she's not used to a manual and can be a bit "rough"). I believe the regular T5 can be rebuilt to World-Class specs. The only differences I am aware of are the synchro material, the bearing cup for the countershaft, and the blocking ring on 5th gear. There may be something I'm missing though.

For the record, the 350 I built has an estimated output of 301HP and 386LB-FT. I haven't had a chance to actually measure the power, but those are the peak numbers I get in Desktop Dyno's engine simulator. Its supposed to be a fairly accurate program.

L695speed

Ok, it is sounding like I just might roll the dice. Dad and I were discussing something like this before we went for the free motor. I'm still gonna keep the T5, and original block in case I decide to go concours. But for now, restoring the suspension, brakes, body, etc and putting in the 350 might be the way to go. Doesn't hurt to have fun with it, when it does run that is. I'll keep up the work I'm doing now and pull the motor out, strip off the L69 parts that I put on that motor and keep everything for the L69.

When I start getting close to doing the motor I'll see what is involved in building up the T5 (so it doesn't blow up in my face the first time out). Keep the advice coming. But it will be at least a couple months before I can even do anything for the motor. Maybe a year. It will all be worth it when I'm done though.

Abubaca

iTrader: (3)

The world class tranny's also has roller bearings under the 1 2 and 3 gears. Might be some slight differences in the mainshaft or gears, meaning you couldn't upgrade from NWC to WC. ...but again, I'm not sure. I just thought I remembered reading that. I actually just finished rebuilding my WC, but I didn't directly need to upgrade from NWC, so I can't remember exactly...

....I'll look into it and get back to ya!

Abubaca

iTrader: (3)

As I suspected. You can NOT rebuild a NWC with a WC rebuild kit.

...but the main case is the weak point. I wonder if the WC is any stronger??? They shift nicer, and should last longer... but....stronger?

92RS_Ttop

iTrader: (3)

Just curious, what prevents you from doing it? I thought the cases were the same and that the extra "strength" of the WC came from the upgraded internals?

ls six

You would need to buy practicaly all the internals to make the conversion, new gears and shafts etc.

Compared to a simple recon on an existing WC it dosnt make any sense, even a V6 WC is a more practical solution with it's odd spline count and less than ideal ratios.

Abubaca

iTrader: (3)

Basically you have the case, soft parts, and hard parts.

The soft parts consist of all your bearings, spacers, shims, blocker rings, shift for pads, roll pins, snap rings, etc. etc. A lot of the bearings and blocker rings were upgraded for the WC. The hard parts are your gears and shafts etc. etc. These are not any stronger in the WC, but are different to accomodate the upgraded soft parts.

I'm not 100% clear on whether or not the case is different. Either way, I know it's not strong enough!!!! LOL

L695speed

Ok, I've been doing some looking around. And thought what if I rebuild the L69 but with a better top end and cam etc. I know these motors are not the fastest and can be a pain to keep in tune, but with the 5 speed and 3.73 they can run with a TPI 305. I'm thinking if I can redo the L69 and have a similar power output to a base 350 I might just do that. The 305 is already restricted, lets see if we can lift some of those restrictions and see if we can't get TTA power out of one. I know a guy with Z28 who is running the stock driveline with a 300 horse 305. Why not do something similar.