evob21

iTrader: (1)

I hope this is the right place since this is a bit of a different question. But like the title says I need some advice and knowledge.
I own a 1979 pontiac trans am, and absolutely love it. The only thing I don't love is the engine. I came with a 403 Oldsmobile engine, which can't make it out of its own shadow. I wanted to build a pontiac 400 stroker that would do about 500 torque and 500 hp. I say torque first because I was building more of a street/road course car, and not a drag car. After reading several articles and doing research I decided I should get an LS motors. This was hard for me because everything I have learned was on the old engines (chevy big and small block, fords ans so on) so LS motors are a whole new world. Because of that I wanted someone else to install and set everything up for me. I am not the person who normally says that, I like to do all the work myself, but because I know hardly anything about the LS motors, I figured it was better for someone who knew what they were doing to do the install. I found someone in my area who could do the install and we talked about what motor I should get. I wanted to do an LS3 because it was the middle ground engine out of all of them. He said to go with an L92 because it would be easier to get everything to work computer wise. I said okay because he knew more than me. I bought an L92 built to Ls3 specs on here not long ago https://ls1tech.com/forums/parts-cla...rice-drop.html. We are now talking about the trans and I am in the dark. I have an automatice and want to keep it that way, even thought I love manuals. He is telling me to go with a 4l80e. I have a th350 that was just rebuilt to take 500 hp for the other motor, and the rear gear was changed to a 3.08 (was 2.41, its fine you can laugh, I did), several transmission guys I have talked to have said to stay with the th350 and build it again so it can take more power just in case. Then figure out the kickdown cable by attaching it to the throttle body (which is drive by cable) and it will be better then a 4l80e or 4l60e. But I'm not sure what to do. It would save me money since I am on a tight budget. So can anyone help guide me on this?

1964SS

iTrader: (1)

It's really a matter of preference, but I would sell the th350 and use a 4l80e.

Pros
1. The overdrive trans will allow you to go with a lower rear gear ratio for added power.
2. The 4l80e is a very stout trans and will hook right up to your harness and pcm.
3. No kickdown to worry about.
4. Added resale value of upgraded drivetrain

Cons
1. The 4l80e will require a gear change
2. You will need driveshaft modified
3. 4l80e may not fit your tunnel without some massaging.

ijimmy

Your 350 will work fine .
If you wish to use an 4l80 its a great transmission ,,,, buutttt , I would not suggest using it or any other overdrive transmission with as tall a gear as you have in the rear , if you are going to use an overdrive transmission , you want 373 or 411 gears in the rear end

tfi racing

iTrader: (2)

Your BOP pattern transmission will not bolt to a LS engine,unless its one of the rare dual pattern units.

1981TA

iTrader: (7)

What's the primary game plan for the car? Drag? Cruise? Road race? Daily driver?

If your road course use will be more than a session or two a year, I would seriously consider going manual.

Jimbo1367

I read on the orginal engine thread they swapped out the valves and went SS. I'd switch the intake valves to LS3s.

evob21

iTrader: (1)

So why should I change to a 373 or 411? Is it just better for performance or keeping the RPM down? (I'm still new to the rear gear selection)

Ya it's not one of those. I'm not that lucky

I'm planning to use it for cruising and street car, road racing, maybe use the car for some daily driving here and there. I originally wanted to go with a manual, but after watching people at the road races I saw that many people lost time in just shifting from gear to gear, this was just at tire rack when people were autocrossing, I'm sure its not the same for all tracks. Thats why I went with a automatic, and planned to put a B&M shifter in the car so I could jump back and form from gear to gear so I hopefully wouldn't loose as much time. I did look at putting a sequential gear box in the car, but that costs was to much.

How can you tell? I did plan to eventually put LS3 heads on the engine, if that matters at all.

1981TA

iTrader: (7)

FWIW, the ability for the driver to precisely control what gear the car is in, and when it shifts, is seen as a major benefits of manuals, and in fact nearly all of the cars that are serious RR toys have manual trannys. It requires more driver concentration for sure, so I can imagine that a few blown shifts might cause problems as you learn, but once you get the hang of it, a manual trans car will almost certainly turn faster lap times AND last longer than an auto.

That is for road course use. Auto-X... I think it's a matter of preference.

Here is a video from an autocross last weekend. A very experienced driver got behind the wheel of my car for the first time and turned a lap time that put him on-par with a new 1LE SS Camaro auto at the same event. Shift timing really didn't enter into the equation. It was more of a matter of how hard the car got pushed.

More runs, and he would have trimmed a few seconds off, but he was teaching me (and I was driving too conservatively).

L92 OLDS

I've been flying the Olds flag for over 25 years....The Olds 403 is a kick *** engine but technologically is obviously outdated compared to the LS platform. The 403 responds VERY well to bolt ons (#5 heads, headers and cam will net you 400 plus HP with gobs of torque). There are many out there running 11 sec quarters in 3800 lb cars. This would have been the most cost effective route for you but it looks like you've already jumped onto the LS bandwagon.

I don't understand why your buddy thinks an L92 would be any easier than a truck 5.3.....Doesn't make any sense to me. The L92 is a great starting point but requires most of the same peripherals as a 5.3 or 6 liter.

Your L92 likely has a drive by wire throttle body. If you're on a budget it would likely be best to keep it and go with an electronically controlled transmission so you don't have to jury rig a throttle valve cable. You will want overdrive for a street car. If you are on a budget, going with a used 4L80E will likely be your best bet in the long run. Why put a modern EFI LS engine in a car with an outdated TH350 trans? Just my 2 cents.

SSZ

Your TA should be very similar to my 80 Z28. I didnt have to massage the floor pans for the 4L80E.

evob21

iTrader: (1)

@1981TA: I agree with you that the manual is better than the automatic. And like I said I wanted a manual. When I was looking for cars I worked at an engine shop and my boss who was a good friend of mine and had many more years of racing experience told me not to bother with a manual because a shifter could be put in the car so I could select gears without the clutch. The courses I would be racing on wouldn't be very big so I would be in 3rd gear most of the time I'm sure. But I also planned to drive the car around town and what not as well, which is not fun in my area but you get use to it. In reality I wanted a manual but had many other pushing a automatic on me. So that's why it's an automatic.

@L92Olds: originally I was actually going to do that. But before I went to far with it I asked people on Transamcountry, where all of them said to drop the 403. A few said to keep it but if I could drop it, then do that and get a 400. So that was the plan, I would find a 400 and build a stroker motor for more torque. I tried to price out everything I could in excel, down to the bolts to get an idea of cost, and it was a lot of money. I read an article talking about ls motors and it showed a comparison of older motors to the ls motors and the ls motors won out. Another thing that appealed to me was that it was slightly better on gas as well and things like that so I changed pace. I actually don't even know the guy, I found an ad of his and it talked about how he does engine swaps in his free time. I didn't want to do it since I was new to it all and didn't want to screw something up. I wanted to go with a true corvette ls3 motor, but his claim was that there were more sensors and computer controlled elements in the car, and trying to get that all to work well with the trans and the computer would take more money and time then it was worth. Like I said, I'm no expert, and this guy had done ls motor swaps in other cars. So I believed him since he had more experience then I did. I am on a tight budget. But I'm going to attempt to go the 4l80e route since it seems like the smarter one to go.

@SSZ: You are correct them should be very close to each other. I'm glad to know not to much hammering, I mean, massaging will have to go on haha

truckdoug

iTrader: (25)

yeah I was gonna say 403's are awesome. killed many sets tires in my cutlass with a torker intake and an ultradyne solid cam.

to OP do the ls swap though. in your budget, budget some time. read up and educate yourself these motors and common issues people face when swapping them. you'll want to know about oil pans and headers and intakes and stuff. spend a month reading. search the FAQ's. check out the HP books from the library. that was the best advice given to me on my swap. And when it came time to do the actual swap the turning of bolts was the easy part, it was all about having the correct parts on hand. And that took some reading.