ok so I have a 92 bird 305 tbi and wanna do a 4th gen swap and what i plan on doing is either picking up a posi disc rear from hawks from a 3rd gen or a rear end from the years from which engine i choose then from there the tranny and engine...question is which one would ou all recomend? lt1 or ls1 yes i plan on keeping the a/c so which one do you think is more beneficial. i was thinking build up an lt1 but i keep hearing ls1..which one requires more work and what all should i know? thanks!

 

Man, I hope this thread doesn't become the swap forum's version of "knocking down a hornet's nest"... But what the heck, I'll dive in.

The advantages to the LT1 swap are that it's much more of a direct swap, so it's less work & less expensive. If you're not looking to run deep 11s or better on just the engine, you just want a decently-powerful street machine, the LT1 would fit the bill, & allow you time to drive it this summer. (Two thumbs up!)

The primary disadvantage to the LT1 swap won't be felt for a little while yet - but within a decade or so, I suspect that some LT1/4-specific parts are going to start to become hard to find. They just didn't make that engine for very many years, so the eventually the numbers won't be there to justify a lot of production.

The primary advantage of the LS-series swap (in my opinion) is efficiency. With designed-in advantages like 15* valve angles, hollow-core camshafts, etc., the earlier engines just can't compete - period. Efficiency means better fuel economy, & better driveability for a given power level. Better efficiency means that (generally speaking) these engines respond at least a bit better to a given mod than the earlier engines can. Also, aftermarket support for these engines is just about stupid - and certainly light-years better than it could have been for the original SBC 12 years after it was introduced...

Of course, since there's no such thing as a free lunch, there's also a significant disadvantage as well, & that's the cost & effort involved in swapping an LS-series engine into a 3rdgen. I'm not going to rehash all of that (that's why we have the sticky posts at the top of the forum), I'll just say that you'd be well-advised to do a lot of reading, both here & in this forum, & if you decide to go this route, make a plan & do everything you can to have as much of the needed stuff on hand as you possibly can.

One helpful hint - if you're not swapping in a "special" (read: unique/oddball) engine like I am, you'll be significantly ahead of the game (in both time & money) by purchasing a wrecked donor car. (Of course that also kind of limits your engine choices a bit, but for many people, that's completely OK.)

Good luck!

 

there is a reason the lt only lasted a few years - it was obsolete the day the first one came off the line

 

Ouch, anyway, I would say the actual swap is equally hard either way, you have to do a harness, modify fuel, exhaust, transmission swap, worry about gauge compatbility, and possibly k-member cut with either one... converting from carb to injected for me entailed the same things regardless of LT or LS engine choice. There simply wasn't enough LSx knowledge around when I did my swap, now you can find it in spades.

V8Rumble got it right, the LS will get you more streetable power with less cam and better driveability.. A mildly cammed LS3 can get you almost 500 streetable rwhp, give up a bit more idle quality and there are folks over 500.. that is impressive. I do disagree about the difficulty however, I really think the difference is too negligible to not choose the LS.

since my bed is made already I am LTx, if I were to do it again, LSx would be my choice and is my future engine of choice when my current rebuild goes. There are the facts and I'm stickin to em. Regardless my puny LT has sent many an LS home crying, good setup is everything treat the car as a whole package not just an engine

 

Says the guy with a 305

 

thanks this is helping im really just looking for oppinions and "wisdom" from those that are older and more experienced..and im getting it! i was leaning towards a lt1 but i am a fan of both the lsx and ltx just still need a little more convincing by either party

 

I have both an LT1 and an LS1 and it really depends on what you want to do. You can build an LT1 that will get you into the 10's and you can build an LS1 that will get you into the 10's. The LT1 will be less expensive to get up front, easier to install since it still can still use regular SBC clamshells, the LS1 you would have to pick up swap mounts to go with the LS1 block mounts.

LS1 doesn't have the low end kick that the LT1 does, if I pull out in my '98 take it to about 1200-1500 and kick it it squats and goes, good smooth torque curve and you can feel it kick in around 3000 or so. The LT1 in my '87 (both cars are T56 cars) when I take it to 1500 and kick it you better hold on because it throws you back in the seat with the low end torque and will torch the tires.

 

The LT1 aftermarket is surprisingly becoming bigger, within the last year anyways. Trickflow is going to release 21 degree heads soon, Dart is just starting to design a 427 LT1 block which could snowball other aftermarket parts to be made, modified LT1 Stealth Ram intakes are now available, LS1-24X computer/coil-pack conversions are now available.

Like everyone says though, LSX is better in about every way. I'm undecided about wheter to go LTx or LSx on my next engine.

Either path you choose, finding a wrecked donor car is the way to go especially if its your first swap.

 

I'm in a LT1 swap. But if I had to choose now I'd go with a LS based 5.3L swap. These engines are cheap as chips right now. Many of the engines going for under $500. Still need a trans then, but a 4L60E isn't hard to find. They make 275hp, close to an LT1 but have far more cam and bolt-on potential. Guys are putting LS6 cams on them and making a serious bit of power for very little money.

 

If you have to ask then
A: you haven't read the plethoria of information avaliable on this and other sites.
B: you've already made up your mind you just want enough of us to agree with your choice so you feel better about your decision
C: you really have no clue what's going on and both swaps are way over your head in which case see A:

LS1 all the way unless someone just gives me a complete LT1 car for like $500 and even then I'd only put it in my 3rd down car. Not my main all out fastest most fun one.

 

Ahhh yet here we go again I agree with V8Rumble. When I did mine LT1 where going for around $1000-1800 complet. The LS1 on ther other hand Where anywhere from $2500 -up. It was not a hard choice for me at the time, but by the time I did a complet rebuild cam..... I could have got a LS1 But you are like most of us anything from a 305 TBI was a upgrade.

 

Probably had more to do with getting sued over reverse cooling patent infringement.

 

well all this is very helpful and I am leaning towards an LT1 swap..this will be my first engine swap so some of this is new to me..with that being said..i am doing my homework...i have researched most of these threads I was simply looking for opinions. but with that being said ive heard that to keep the a/c a good amount of work is need...having a black car w/ t-tops in florida...lol nuff said..what all would be required is it really that hard or are people blowing it out of proportion

 

The problem is not very many LT1 swappers have kept the a/c so not much information is out there.

I don't think I've seen one post/picture on this website of anyone who has successfully made the a/c work in the stock LT1 f-body a/c location. If they have, they haven't posted what parts they used or what venders they went with.

I have made the f-body a/c work with stock v6 a/c lines but I had to get an expensive aftermarket bracket to put the a/c compressor in a different location which made it kind of in the way. Another member has made the corvette LT1 a/c work but had to get corvette brackets and custom lines made.

I might be working on getting custom lines made this summer for the LT1 f-body a/c compressor to function in the stock location. Custom lines would be the cheapest solution and shouldn't be that hard to have done.

 

Where could I get that aftermarket bracket and what's the estimated cost of custom ac lines?

 

prolly easier to get all ls1 fbody lines, and ac parts.
stock kmember must be modified to use ac with ls conversion mounts, may have more luck going with tubular kmember. alot more clearance.

 

He's not going with an LS1, but leaning more to the LT1.

You can use the BFH mod on the k-member for the compressor to clear, I have a 4th gen condensor in place, I need to get the hoseblock for the compressor, I found on at docsblocks that I think will work, it costs like 12 bucks for it. Then I'll get a set of lines made up to goto the factory dryer and evaporator and hopefully get it wired up to the stock 3rd gen controls since the LT1 PCM controls the compressor and see what happens.

 

Hey im new here my names trevor and heres my .02 worth. I found my lt on craigslist complete with comp and harness, ac lines everything. Its all only got 10000 miles on it. originally advertised for 500 dollars I got into a bidding war in the guys driveway, ended up givin 700 for it. and i pulled it too. so im tryin to build this thing on a budget. I think with one modification to the compressor manifold lowside hose i can marry the lti comp and hoses to the 3rd gen condensor and drier. the highside line to condensor is already the same. so when i do ill post pics thanks trevor

 

oops wrong picture