Good afternoon everyone!

I have a 1984 Trans am with the 305 in it, now originally I was gonna build a 400 sbc I had laying around that idea is on the back burner for now as the opportunity to acquire a 5.3 LS has just come up. seeing as my car is my daily driver (atleast it is for now) would it be smarter to run the 400 or the 5.3? I am honestly trying to make a mild street car so I was thinking roughly 400-450 WHP. funds are pretty limited as I go to school but I had summer off so I would be working and setting money aside.

I know that engine swapping will take more time and money than I expect so I will definitely get a beater with a heater while the cars on stands. I would appreciate all opinions. thank you.

 

If it were me, i'd go the 5.3 route. If you left it stock, you'd have a 300+hp mill that will get you 25mpg and be rock solid reliable. There will be a higher cost of entry for mounts and such, compared to the 400, but you'd probably come out higher with the 400. A small cam will give the 5.3 a serious boost in power too.

 

Minimal conversion - use the 1996-2000 5.7L truck block. Add the aftermarket crankshaft and you can build a 383.

 

Just as a reality check, the all stock LC9 5.3 that I put in my 91 camaro made 276 rwhp . The all stock LS3 that I replaced it with made 368 rwhp.

 

That seems low for an LC9. Did you remove VVT from that motor? 276 is more stock LM7 territory. OP may want to meet in the middle with a truck 6.0 as I'm sure an LS3 is out of his price point.

 

That's right in line with what a stock 5.3L does in our cars.

https://www.thirdgen.org/forums/ltx-...o-results.html

 

Neither one of those engines is even remotely capable of making those numbers with a "mild" build. You can do it with a turbo on the 5.3L though.

 

If it were me, I'd drive it as-is and buy a cheap daily beater.
Then you start building an engine or modifying the car.

 

If it was me, I'd park it indoors, buy a beater Civic or something that doesn't use much gas, focus on college, and dink with engines after all the student loans are paid off.

Unless of course you're AHELLUVALOT smarter than me (quite possible, I freely admit) and college isn't even remotely a challenge; and at the same time, have AHELLUVALOT more money than I do, that you don't have to work for.

 

I appreciate the input, I am not familiar with building engines so this is a good reality check. thank you!

 

I definitely agree with that. I appreciate the input thank you!

 

I would like to toot my own horn and say I am pretty bright but the trouble I get myself into says otherwise Thank you for the input!

 

I appreciate the input! I agree with you on that. Thank you!

 

Thank you for the reply! I appreciate the reality check. if you have the time to respond, do you think attempting to pull a ls from a 4th gen would be better? thank you again!

 

College, student loans and your level of smartness aside, what shape is the 400 in?
Thinking is: if it's a runner, then the swap from the 305 to the 400 is minimal. There may be a few hiccups along the way (flexplates for example) but otherwise it's a nuts and bolts swap. Or should be anyway.
The LS, regardless of its condition will require a lot of extra parts to make it fit. Parts readily available yes, but parts none the less. Everything becomes more complicated. As an example is the exhaust. Nothing for these cars drops in without at least some level of fabrication. Even the Holley/Blackheart option is gone.
If it's a project that can be completed over a period of time (read that in years from what I gather about your current situation) then the LS is less of a hassle. If you have a few hundred bucks kicking around (maybe several hundred) then the 400 could conceivably be a weekend install.
I've done most of the math as I also have a complete LM7 (a complete 03 Tahoe to be exact) and have weighed the costs of the swap. The good old gen 1 comes out ahead.
As for 400-450 RWHP, that's a whole other matter. Neither engine is capable of 500-550 crankshaft HP without some extra work.

 

A 3rd gen can only support so much power before all the stock parts get thrown away and it becomes a total custom build. 400 - 450 RWHP is over that threshold so you're "all in" at that point.

Given that.... and how much money it costs.... it's wise to consider the end value of the car because almost no young person keeps their car long term (no matter what they say). You're at a stage in your life when you're moving up and this car probably won't interest you very soon after getting your first professional job and the pay checks start coming.

Problem with an '84 Trans Am is that it does not have much intrinsic value (most Firebirds don't). You put a lot of money into it and you don't get much back out when you sell. Whereas if you put that same effort and money into a Chevelle or early Camaro then it will increase in value a lot because it has more intrinsic worth. Even a Factory 5 kit car would be financially smarter than building a 3rd gen. This is something I learned too late in my life to implement, so now I have a built Firebird that I can't afford to sell.

However, the reality is I built my car bit by bit on a budget I could afford and it took a long time to spend all that money. Didn't happen all at once, and I didn't have the big stash of cash to buy into these other options. So even if somebody had given me that "good advice" years ago, it still would not have mattered because I would not have been able to do it.

Now that I've written this I'm trying to figure out what's the point of this nauseating speech.... .... Maybe the point is from the practical side of things that a hobby is just a hobby and don't spend more than you're willing to lose.

 

LS swap would be strong and reliable but will be expensive and not straight forward as a SBC swap...Get that $$$ together first it almost always costs 2x what you figure.

 

What ever you decide , I don't think these cars are a good choice for a daily driver. If it's your only car it is a bad choice. If you have a reliable daily car and a good place to work on your toy car, a place where you can leave in in pieces for long periods of time, then do an LS swap.While I had my LS swap running in about 2 months , It went into storage that fall with bugs still to be worked out. It was almost a year before I was willing to take it on an interstate trip.

 

All above and make a smart Real Estate buy, before big dollar vehicles! It worked for me!

 

Money and time are likely the biggest issues being in college. A possible middle ground option to consider is sbc 400 swap as it would require the least amount of swap parts, and converting to a holley ecu like a terminator x. Then if you when LS later you already have a few of the major parts. Moving to modern fuel injection should keep everything reliable. I have a detailed thread on installing a terminator x ecu on my L98, but you could use it on most any port injection manifolds.

 

Exactly. It also worth saying that the time you put into should be enjoyable and not rushed to meet some artificial deadline.
Work on it as time and money allow. Keep it in context.
I AM the poster boy in that regard!

 

Fortunate for me I've been given a pretty good life. The car was originally my dads before it passed then it was given to me. as for losing interest, I had this happen not to long ago ironically I was dead set on a 2nd gen firebird for the longest time but reading everyones builds on here has re-inspired me. but then again. you are older than me and have experienced building one of these cars. I'm as alice cooper would say "a boy and a man" so perhaps I will change. as always I appreciate the replies and all the input thank you!

 

Just remember, a running and driving 250hp car is more fun than a theoretical, half built, 500hp car stuck in build limbo. Many of us have gone down this path.