Question

[Btown555]

Watsup everyone I just registered to this forum and the threads have some good info.I got a 89 firebird v8 305 tpi and I just wanted to ask a couple questions if someone could help me with.I wanna start off by throwin a flowmaster on it and everything together is a little pricey I was whondering if i get the 80 series crossflow 3" dual with some cheap exhaust tips if itd be alright or if anyone knows some other good exhausts? I also wanted to get a chip to take off the top speed limiter anyone know any good places that sell these? I seen some comp chips on ebay its called like guerilla chip it says it adds lik 50 horsepower i think thats bs but are they good or? I read the guys first post on 305 good info.If anyone could help me out with this itd be great thanks and if you know any other straight mods i could put on i always like more info

[wrightz28]

Welcome to AF!

There's going to be debate on the exhaust system for sure, but I had the same system, coupled with Edelbrock TES headers on my 305 Z and I was happy with it. Not too overly loud (unless the load pedal is used) and a throaty tone (enhanced by the TES!).

The big "speed limiter" to overcome is the lazy cam, not the ECM. The cam in most of the TPI motors have too narrow of a band and the motor just falls on it's face at low(er) rpms. On the flipside tho, the trade off is a healthy amount of torque, which is what gives you that seat of the pants take off. A large(er) rear gear further takes advantage of that, 3.73:1 = "good bye", but again, lowers the top end speed.

[Btown555]

Yea but it your saying it makes your car slower by taking off the top speed governor? and also what can I do for suspension cause the car needs something it rides kinda messed up when i hit a bump

[jveik]

yeah the exhaust probably wont make a huge difference if you keep the motor stock. maybe 10 or 20 horsepower tops. the best thing you could do for the money is maybe look into some vortec heads. GM sells them brand new for i think about 300 bucks apiece "correct me if im wrong." the next most important thing would be a better cam, but definately make sure not to put a bigger cam than the heads can handle or one so big that it kills lowend torque altogether.

if money was no object to ya, i would just straight up suggest that you replace the 305 with a 350, the 350 has the same stroke with a larger bore, so they rev just as high as a 305 can. those extra 45 cubes are the most important part. i believe gm sells their generic shortblock (no heads or anything, just the block with the rotating assembly pre-installed in it) 350 with 4bolt mains for 1000 bucks, so it aint exactly cheap, but it would kill any 305 out there with the same mods. i have read of people making just shy of 400 horsepower out of one of these shortblocks and they actually were able to run the heffer on 87 octane!!!

if money is an issue, then keep the 305 and get a good exhaust, intake, and at least a little better cam. that all would probably be under 1000 bucks.

its too bad your motor isnt carbureted, they make more power dollar per dollar, since getting as much high rpm power out of fuel injection usually takes a pretty decent amount of cash and you have the computer to hold stuff back. with a carbed non computer engine, you can rev it till it breaks a rod lol. i almost did just that one time in my pickup. i wanted a new engine so i poped the th400 into first and started speeding up and after a while i looked and the speedo sed 60!!! sounded like a freakin ricer and im sure to this day that old 350 never quite ran the same:-)

[Btown555]

Yea its already got a k&n air filter so should i work on getting some vortec heads first? then grab an exhaust and a new cam? also is there any like minor suspension additions that I can add to make it a smoother ride? thanks for all the help

[Morley]

If your car came from the factory with speed rate tires..ie; 245/50 VR 16's...there is no speed limiter in your PROM program. It would be set to maximum...255mph.

[Btown555]

on the vortec heads wouldnt you have to convert it and doesnt it mess other stuff in the engine up? thats what I heard..Well wouldthe best thing to do is start off with some headers and exhaust and cam

[jveik]

well, the vortec heads only mess up your intake manifold. you have to buy one specifically made with the vortec bolt pattern in it. Other than that i dont think theres any issues, other than the fact that they only can accomodate about .475 inch valve lift unless you put down some more cash for higher lift modified ones (google "scoggin dickey vortec heads" or something, as long as its scoggin dickey)

maybe they use different length pushrods or something also, but thats not a huge problem, i dont think they do anyways, just youd want to make sure before trying to fire it up that everything is right on the money

[Btown555]

I also was looking at another firebird and the guy has a 89 he says its a v8 but im not too sure if it is the speedometer only goes up to 120 and dont the v6 cars usually say that i dont really know how to tell the difference if someone could help me

[ikeyballz]

if its a 89 the only way to really find out is to pop the hood and count the spark plug wires.

the formulas had the same body as the V6'ers so you cant really guess...

also some V8 camaros had really low spedos.. so.. you cant go by that eithier.

[jveik]

yeah if you can easily tell if its a v-6 or a v-8 just by looking at it. if youre still confused then modding a car might not be in your best interest. i would just ask to see under the hood.

you guys are luckier than you think lol my speedo in my truck only goes up to 100, and thats only cause it came with a 454... the smallblock ones only go up to 85!!! im hoping to be able to hit at least 140 with the new motor and that crappy 100mph speedo just wont cut it...

speaking of speedo's, i got into an argument with this guy one time about whether a car can go over the top speed of the speedo or not. he insisted my pickup would stop speeding up once the needle hit 100... what an idiot.

[Whoaru99]

If you are going to do mods start with the exhaust first. It will help make power with your car as-is and will still help, perhaps even more, as you add more mods. Not talking just a muffler here, go for the complete package - headers and all.

You can put all the chip, cam, heads, intake, etc up front, but if you are trying to push exhaust out of that factory system, it's kind of a waste of all that good stuff up front.

[Btown555]

My bad its a tbi and i am getiing a tpi also but its a 305 its already got a nice 3" exhaust and headers ad air filter anything i should do it whips real quick already

[Savage Messiah]

I always say... intake, exhaust, gears.