hp mods for 305

For the Trans Am (87) I noticed they had a few less HP than the same year camaro's due to some engine restrictions or whatever, Anyone know what caused this and How would you get this HP back.

I was also looking at getting a big intake and a dual exhaust, not sure what kinds.

I *believe* it was intake design, but don't quote me on it :)

So if i get like a custom intake it should add alot of hp?

save your money and buy a 350. you can find good used 350s for cheeper than moding a 305.

well he has a point, a 350 is better. however some people dont want to make that kind of swap. if you look at some years, like 89, HP from a 305 and 350 was only 15hp. So if you want to you can throw an intake and exhaust on it. Just do stuff that you can take off and put onto a 350 if you want to later. I wouldnt mess with aftermarket rods, pistons, or crank.

I'd say the difference would be in the plastic intake tubing. Although the difference is negligible. Just get an aftermarket one. It probably won't even be a noticable difference. Start off with just a thorough tune up.

I'd say the difference would be in the plastic intake tubing. .

No, I'm talking along the lines of actual intake *manifolds* were different between the GM car and the Pontiac car :)

But 87TransAmGTA, I dont know about a *custom* manifold, there are SEVERAL good manifolds out there, and for decently cheap at that ;) You just gatto know what your looking for.

But there is nothing wrong w/ the 305. Well, unless it's a tbi. THEN your SOL. Otherwise, you will be fairly well-off w/ that 305 unless you have the time, money, and patience to swap to a 350.

No, I'm talking along the lines of actual intake *manifolds* were different between the GM car and the Pontiac car :)

This i have a problem with. Thats just blatently not true, and you must be just making it up off the top of your head because not only is it not true ive definitly not ever heard anyone say that. The same engine between both cars is the exact same, only difference would have to be in the style of air box

Im gonna chime in here and say that 85_305 is right. The intake runners are slightly different in some way. Can't remember how exactly.

N20!!!! then move onto a 350 :D

Im gonna chime in here and say that 85_305 is right. The intake runners are slightly different in some way. Can't remember how exactly.

Thank you Jon, I didn't think I was crazy. I am pretty sure that the design of the intake manifold on the Pontiac's was responsible for a 10 hp loss to it's Chevy counter part :)

Im gonna chime in here and say that 85_305 is right. The intake runners are slightly different in some way. Can't remember how exactly.


No. You're just wrong. It's the exact same engine. It'll always have the exact same intake manifold on it. And if you can't prove your hearsay don't spread the false rumors.

EDIT: The only difference in horsepower is going to come from a different cam offered in a 5speed vs auto or non-g92 vs g92 car.

Im gonna chime in here and say that 85_305 is right. The intake runners are slightly different in some way. Can't remember how exactly.
I didnt want to go too far out on a limb, because i dont know a whole lot about the tbi, cfi etc engines they used i couldnt say for sure there was absolutly no difference, even tho i was 99% sure they were the same. But as soon as youre going to start saying that there is a difference in the tpi runners flags are going up :bs:

the only difference between camaro and pontiac cars was the plastic intake, not the actual manifold itself. The camaro got the plastic Y type that went down in front of the car and thats why they picked out the extra few ponies, it was a ram air effect.

For the re-re's that dont know what their talking about, check this out :rolleyes:
(Look at the botom of the '92 model year Camaro)
http://www.thirdgen.org/newdesign/tech/techdb.shtml

See that part where it says "Note: These are Camaro ratings. It is said to take around 5-10 HP and TQ from TPI Firebirds because of intake design."
??
Ya.. so Jon and I would appreciate that appology now :)

Sounds like we aren't the ones that need to get our "hearsay" facts right Matt.
Be it the runners, or not, I may have that wrong, but I know it was from the intake manifolds design in whatever way. I coulda swore it had to do with the runners though.

^Indeed Jon; people on this board hear somthing weird and immediatly think you must be b/s'ing and it's so fricken annoying.
But I, as yourself, also thought that the problem was actually in the manifold itself. I *knew* it was intake-related though :cool:

Ya.. so Jon and I would appreciate that appology now :)

Apology for what? It doesn't refer to the manifold itself, it refers to the plastic intake tubing from the throttle body forward. The birds had a sharp 90 degree bend and went over tho the passanger side where an airbox sat sucking hot underhood air while the maro's having a taller hood line could use and intake setup that went directly over the core support.

Apparently i need a bigger flag :confused:

This is nuts.

Look at the airboxes

Camaro airbox (http://users.erols.com/gcwestph/engine%20front-sm.jpg)
Firebird airbox (http://efiswapshop.com/jodi-firebird-1.jpg)

Read this article from GMHTP (http://www.gmhightechperformance.com/tech/0303GMHT_Breathe/index.html)

It turns out that third-gen Firebirds have a unique problem in that their low hood line and passenger-side-only intake ducting makes it very difficult to route lots of cold air into the motor. This is not really a problem with stock displacement engines with mild bolt-ons or even head/cam packages, but it is a big problem with bigger engines such as ours. Third-gen Camaros, on the other hand, have a higher hood line which simplifies the buildup of a custom intake pipe when one is actually needed. Fortunately, the dual snorkel factory setup found on all tuned-port IROCs and Z28s flows a greater amount of air than the sibling Pontiac setup. The Camaro dual-snorkel is also easy to modify for increased flow for not a lot of extra effort. Unfortunately for Firebird owners, the Camaro dual-snorkel setup cannot be swapped over to the Firebird because of the 'bird's lower hood line. Bummer.

Yea Matt, hate to burst your bubble, but every Camaro and Firebird from 82-02 that had a v8 used a chevy motor. The Firebird LG4 was identical to the Camaro LG4, as were all of the other V8 options.

- Justin

Yea Matt, hate to burst your bubble, but every Camaro and Firebird from 82-02 that had a v8 used a chevy motor. The Firebird LG4 was identical to the Camaro LG4, as were all of the other V8 options.

- Justin
I try to tell my dad that every time we talk about L98/LT1/LS1 Trans Ams

"Do you have any idea how long ago they quit making 'Pontiac Motors'?"

Yea Matt, hate to burst your bubble, but every Camaro and Firebird from 82-02 that had a v8 used a chevy motor. The Firebird LG4 was identical to the Camaro LG4, as were all of the other V8 options.

- Justin


I am very well aware of that :)
I just thought that *something* along the lines of the intake was different, causing some sort of obstruction.

Apology for what? It doesn't refer to the manifold itself, it refers to the plastic intake tubing from the throttle body forward. The birds had a sharp 90 degree bend and went over tho the passanger side where an airbox sat sucking hot underhood air while the maro's having a taller hood line could use and intake setup that went directly over the core support.

I didn't mention any names, so how do you know I was reffering to you ;)
I know it wasn't the actual intake, but was instead the plastic tubing. It's just kinda weird that just by screwing-up the plastic tubing, that much hp was lost :confused:

again, the camaro got a "ram air" effect from its intake the firebird did not.

again, the camaro got a "ram air" effect from its intake the firebird did not.

May I reiterate that "Ram Air" is a myth? The only benefit is fresh, cold air (which is an amazingly effective benefit).

I didn't mention any names, so how do you know I was reffering to you ;)

Oh....Okay, well lemme go ahead and remove my foot from my mouth then. :D

You guys need to attend a car show or two and actually *look* at the under-hood differences!

As someone who has noodled with third-gens for going on fifteen years straight, I can tell you that for sure there is no difference in a TPI longblock engine, be it installed in a Pontiac or Chevrolet. However, Pontiac used their own electronic engine control and nduction system whereas Chevrolet used their own. They both used similar ECMs from AC Delco, but sometimes you'll find speed-density and electronic speedometers on the Pontiac whereas the Chevy still had mechanical speedometers and Mass Airflow sensors.

Chevrolet Camaros with their higher hoodline had a less restrictive ducting to the TPI whereas Pontiac put in a tube and routed it to a circular air cleaner assembly that was tucked up into the right corner of the fender. All horsepower differences were due to the induction plumbing and possibly the electronics and tuning. Whenever you talk aluminum or steel, however, the cars shared identical parts.

i do have to say that the only difference is the plastic that goes to the filter. man i need some of u guys to talk to a friend i have cause he has been tellin me that the firebird have more power than camaros so i told him that let me get my car put back together and then i will light him up, plus i am not puttin my car back together stock. :D

[QUOTE=iansane]May I reiterate that "Ram Air" is a myth? The only benefit is fresh, cold air (which is an amazingly effective benefit).

well again, camaros get that fresh cold air from the plastic intake system it uses.

Right, and you can do the same thing with the Firebird through the SLP cold-air induction kit that they sell. Or, you can get the rather cheaply made but effective solution at http://www.ramairhood.com and suck it straight off the front of your car. I must say though, when the idle air control circuit opens up, it sounds like the car grows a roots blower.

I must say though, when the idle air control circuit opens up, it sounds like the car grows a roots blower.

:lol:
Thats kool :cool: