need help with 79 Trans am upgrades for most Horsepower

Home  \  Classic Cars  \  need help with 79 Trans am upgrades for most Horsepower

Hey guys

I drive a 79 trans am 301c.i. 4.9L 100% stock

What are some of the things you guys would recommend that i could put into my car that could boost my hp a lot. Right now my car is all stock and i read that my engine is only pushing like 150horsepower. Also what type of Engines would be able to fit in my car w/o to many problems(if i can scrape up some money to buy one) Or if it would just be better to put hedders and new exhaust and take off the muffler and try to make other improvements to the engine

So if you guys could help me out here that would be great!

also if you would like to Instant Message me my name is TA79Kid and my emails is

posted by  TA79Kid

well if you have the money then a new engine would be better, there should be loads of room in there, they fitted a 440 big block in the same engine bay so i dont see why something like a LT1 or something along those lines wouldnt help, the other advantage, is that tuning parts for that engine are so pleantiful and really cheap. For ~300 horses you could pull one out of a smahed up camero or vette.

Doubled your power with a trip to the scrappy.

Its posible to get alot out of these engines, just becareful if you want to drive it on the road that you end up with a driveable power curve.

with NO2 ported heads, chiped and maped you could get ~550-600bhp cost about $5k if you get some body to do all the work for you probibly get it down to $3k if you did the work yourself.

posted by  cinqyg

He said what can he put in his engine, not engine bay :thumbs:

Please disregard everything this guy told you. If you want better performance, upgrade your FI, ignition system, exhaust system. If you want more power maybe you could fit a turbo charger on, and a cooler. If you want more power(which you said you did), then your going to have to do the performance upgrades to see the real difference. :2cents:

posted by  DodgeRida67

First of all, the 301 was and always will be a dog. It suffers from low compression, bad heads, thin cylinder walls and a very weak bottom end. The Turbo was good for around 210 hp. Decent torque though at around 340 lb ft. That being said lets assess your situation. If you current engine is getting tired anyway then get a Chevy 350. They put them in some T/As and they are cheap and plentiful. Performance upgrades are readily available. As far as the 440. Pontiac got in enough trouble putting in Olds and Chevy engines in Firebird, I don’t think they would have stole from Mopar. If you go with a big block you have to start worrying about suspension and cooling issues. Also, with a big HP boost you will need to get a better tranny than the factory Turbo 250 that came in the non turbo birds. I’m not sure about the rear end strength. If your engine is in good shape you can go the intake/ exhaust route but I would stay away from the turbo. The factory turbo engines were different than the non turbo. They had beefed up parts to handle the boost.
Just my thoughts

posted by  my67falcon

The 350 is a good choice as you can get the mounts from that engine in a camaro, and it'll be a bolt in. The 400 that was available in the Trans Am is a bit pricey and hard to locate, and costs to build up. The 403 Olds engine that most 6.6 liter Trans Ams had in '78-79 is actually pretty cheap to make fast, though while they are cheap to buy, actually finding one might be hard. It's also no heavier than the 350 Chevy or 301 Pontiac engine, so it won't hurt handling, espeically if you have the WS6 handling package already.

The 301 is going to always be a dog. The factory turbo versions are better, and can be easily made to make a lot of power (a small set of vice grips on the mechanical wastegate lever, turned 90 degrees, ups the boost and power rather easily)

posted by  ChrisV

I dont think that the point of the question was how to upgrade the engine, more pitched at how do i get more power, seems to me that people agree that its a nasty engine, so why dont we go for a chevy small block?

posted by  cinqyg

Well now i know i have to drop the 301c.i. it sucks for power and seems like it wasnt biult worth anything so ill try to find a new engine and put some new mods on

Thier is a guy selling a 1972 Grand Prix with a 403 in it for about $1,000 Do you think it would be a good idea for me to just buy that car and strip it for the engine and then put my 301c.i. in that car and sell it off or is thier any more parts in that car i could use or would it be better just to buy a complete new engine and not have to worry about the other engine having problems

also since my car is all stock do you think it would be a good idea if i were to buy H-pipes or X-pipes? also should i just cut off the muffler or go with flow masters? and where could i get some nice headers for a good price?

Also by the way my car is an Auto transmission (sucks i know) and it has 77,000 miles on it.

posted by  TA79Kid

I dont like auto's but they are easier to handle on every day drives which large touques and HP as you not having to operate the clutch which can really get you down in traffic, becuase its either longer than your grannys legs or so hevy it feels like your helping the druids put stone hendge together. probibly not the right one for the job though.

posted by  cinqyg

You make it sound like your holding in the clutch for more than 1 second. :screwy:

posted by  DodgeRida67

jams here m8e are often rolling ones but between 0-5mph so you cant avoid the holding the clutch. Cliffy will back me up, traveling from guildford to rickmansworth your left leg/knee, will feel like its just run a maration, especially if your driving something tempremental that requires double declutching, or a high torque yank tank.

posted by  cinqyg

It’s a lot easier to go with another auto when swapping. I’ve owned a “77 T/A with auto and a 400 / “80 T/A with auto and 4.9 (when I lost a race against an old guy and his grandson in a station wagon it had to go) and a “77 Formula with a 350 and 4 spd. I’d have to admit that the 4 spd Formula was much more fun to drive. If the 403 is a good engine and the tranny is good it may work out for you. I’m not a GM expert, but I was under the assumption that the 403 was made from 1977 to 1979. Am I wrong? Could the engine be a 400 or a 455? Also, the original post asked what he could do to boost power and what type of engines he could swap in. I believe the “upgrade the engine” came into play when he said “Or if it would just be better to put headers and new exhaust and take off the muffler and try to make other improvements to the engine” That’s why we mentioned the weakness’ of the 301.

posted by  my67falcon

The '73 shouldn't be a 403 in stock form. In fact, those years it wasn't sharing Olds engines, so it woud have had a 400 or 45 in stock form, which are different than the Olds engines. Regardless, the factory parts are available to bolt whatever engine it is into the Trans Am, as the F body had Olds, Pontiac and Chevy engines in it from 6 cyls up to 455s at one point or another.

While you should match the engine and trans together, the BOP bolt pattern should be the same so the trans from one should bolt to the engine of another. Chevy bolt patterns are differnt, so you can only use them with chevy engines, and vice versa (yo'd have to get a differnt trans than you have to use a Chevy engine).

The automatic will be fine. Install a B&M shift improver kit in it and you'll have firm, fast shifts that you control, while still having automatic operation for use in traffic.

My 403 powered Trans Am was a '78, but most of th einfo applies, as I built mine like the pair of '79s that were also in my sports car club. Headers and true dual exhaust (but an H pipe is ok), a rejet kit for the Quadrajet 4 bbl, and a distributor recurve kit. Dial all those in and with no other changes you can make a 16 second car be a low 14 second car even with the stock 2.43 rear end gears. With 3.0s or 3.23s, that same combo runs low 13s. All for just those three engine mods to a 403. Add a small shot of nitrous, and you can dip into the 12s for very little money.

I didn't believe it at first, but since it worked on both those other Trans Ams, then on mine, I'm sold.

posted by  ChrisV

Well the person i was going to buy that grand prix from happens to have just left for about 1 1/2 months down to Arizona so im not even going to try and wait for him to get back to buy the car and thats assuming i could get it for that price so im just going to try and find a decent engine and a new transmision and then try to get more performance out of it becouse i dont see the use of adding mods to my 301 if eventually im going to get rid of it. So if any one knows if it would be a good idea if i should just drop a chevy 350 in and get a new transmission or would my transmission still work for the new engine? and if you guys know about how much this all might cost me so i have some idea how much i might have to spend/save up that would be awesome

thank you very much so far for all of your help

posted by  TA79Kid

You could mostlikely get a bell housing which would fit the 350 to your existing tranny, but its up to you, in the main mechanicals on a car are the easy bit to fix as most people can get them right with a limited amount of skill and alot of persitance, body work is another kettle of fish. I would think that you should be able to find a rot box with a nice 350 in, think about how many 350 units have been produced, in one form or another its been running for 35-40 years

the guys in the states would be much better qualifed to where you would source one from, but i am sure that ifyou look around the net then you will be able to find lots of places.

have look at this its a good read even if your not into rods

posted by  cinqyg

As I said, you can get factory mounts for the 350 in that chassis, as it's very much a Camaro. And since the 350 is going to most likely be a Chevy motor, you need a Chevy trans to go with. It's pretty easy to get an engine/trans combo as a unit out of a parts car or as a unit from a private party.

Look in your local convenience store that carries Auto Traders. there shoudl be a magazine on the same rack called Buy&Sell, or Want Ad Weekly, or something like that. In there will be all sorts of good deals on automotive parts. Look in not just the auto parts, but in the parting out sections, truck sections, etc. Often you can find complete running engines for under $400, and good used transmissions for under $100.

posted by  ChrisV

pls send me 1

posted by  cinqyg

I would go with 350/350 turbo tranny thats what is very popular in everyday driver miscle cars thats what i would go with its whats in my Nova

posted by  Nova

Thats what, thats what, thats what. :laughing: :laughing: :laughing:

posted by  DodgeRida67

Well it looks like things are finally looking up for me... maybe..

The guy with the 1972 Grand Prix is back in town for about a 1 or 2 weeks so hopefully i can buy it.

But before i buy it i would just like to run it by you guys that the Rebiult 403c.i. engine and the brand new transmission would stilll fit fine inside my 301c.i. 79 T/A or am i about to waste money?

Also about how much would it cost for me to take it somewhere and they take the engine and transmission out from the grand prix and put it into my T/A then take my engine and transmission and put it into the Grand Prix. Just a rough estimate would be fine i just need to know if im going to spend more on labor then the actual car :oops:

posted by  TA79Kid

The 403 engine/trans will fit in your the early 70's they put 403 engines in t/a's. Finding the mounts might take a little of searching but it shouldn't be too hard to find....also, you might want to upgrade the rear of that t/a before throwing a fresh 403 in front of it. A fresh 403 could probably turn that 25yr old differential into "mashed gear stew". Another thing to consider would be the condition of your front springs...if they're not in good shape expect the nose of that t/a to sag a little.

Good luck!


posted by  Sick88Tbird

Ok thank you for the advice,

btw do you know about how much this all might cost me?

I am now working 2 jobs and i am going to try like hell to get this car on the line before the end of the summer.

also does anyone know how much the 403 could put out in hp?

posted by  TA79Kid

As for power, I didn't ever do a dyno run on my 403 Trans Am, and I don't recall if any of the other three in my sports car club did, either. All I can tell you is that with a stock '78-79 403, the three mods I mentioned dropped the cars from a 16 second quarter mile to a 13 second quarter mile, with the stock 2.43:1 rear end ratios (and the stock rear end even behind the 301 will have no problems holding up to it). The ONLY thing that might be an issue is rear end ratios. My friend tried to up his rear end ratio to a 3.23:1, and the car ended up slower in the quarter mile, due to hitting maximum rpms at 3/4 track (the 403 really doesn't breathe much past 4500 rpm...).

You should be able to go to a local auto parts store and get factory engine mounts for the 403 in the '79 Trans Am.

posted by  ChrisV

it isnt that hard a job you could do it yourself, the tools will cost less than the labour. to get it all sitting pretty its about day and a halfs work to do the 2 cars if it all goes to plan. how much to they charge an hour?

posted by  cinqyg

"Speed is just a matter of much do you want to spend"

this holds true for just about everything....if you get that 403 and put a good intake/carb. as well as a mild cam and headers you'll be able to easily push 325-375hp but your torque will probably be up in the 400-500lb-ft range....

those engines were definitely low rpm torque motors... due to the small int/exh valves and rather small ports(BOP big blocks were known for tiny valves and smallish ports) you could probably make power up to about 5000rpm with the right cam, manifolds and carb.

a few months ago i put a new clutch in a late-70's camaro Z-28...the thing looked like a dog, i mean it was beat to hell. When i popped the hood there was a 389 pont. engine staring me down with headers, edelbrock intake and carb. Needless to say when i was done i had to see what it had...lots and lots of balls, that's exactly what it had. Amazing low-end grunt with decent hp at 4000-5000rpm. With that new clutch i had no problem chirping 3rd.

the customer picked the car up and complained that it wasn't fixed...says it was still hard to shift....i had to explain to him that's one of the carachteristics of the Muncie M21...they didn't call it a rock-crusher for nothing...hey the grinding was gone though!-a little off-topic but oh well


posted by  Sick88Tbird

TAKid,your best bet is to try and find a 76-78 400 cid out of anything,and if you get the Y-pipe,its a bolt in.Motor mounts,exhuast,wiring,fuel pump position,trans,its all apples to apples basically.The 301 was a lightened for emissions Pontiac V-8.

A 79 T/A will have a 8.5 inch rear(bulletproof),a TH350,and the engine bay you will need for the swap.

Also,,take a pass on any type of hedder on a Pontiac.Hell hath no fury like a set of hedders that you cant see 6 of the bolts.A 76-78 400 will have 6x heads with decent manifolds.Run duals if it's cool where you live.

posted by  TurtlePimp

A 79 T/A will have a 8.5 inch rear(bulletproof),a TH350,and the engine bay you will need for the swap.


Hows about a smith and wesson 0.44 magnum, only place a police force uses them is in Kentucky. Tells you alot doesnt it!

And if it doesnt work i have a nice big 155mm L7 at work!

posted by  cinqyg

Your Message