hey guys some of you probably already know i'm new at this so what can I do to a stock 1990 305 tbi engine? I've seen mods out their but they usually end up being tpi only mods, so what can I add to my engine?

 

It going to be said, might as well be me - add a 350!

 

I had the same idea a while ago, hmm i have a 305 what can i do to build it up, everyone says go 350 go 350 but i was hesitant to do it, my 305 with 79,000 miles on it had no problems everything ran great and my other 305 LB9 engine sitting in my garage with 62,000 miles on it seemed like the engines i wanted to trust low miles, knew they ran great nothing worn out or bad i got offers ill sell you a 350 250 bucks 180,000 miles on it and i have to spend all kinds of money to get the heads done beacause no one wants to get an engine all together and have bad valve seals they take it all apart so you change the stuff to be safe and then 180,000 wear out valve springs pretty good and the cam get worn especially a 350 with flat tappet lifters i rebuilt a 350 truck and put a new cam in it and when i pulled the old one out a few of the lobes were completely gone!
But it all depends on how much time and $$$ you want to spend, if you have money get a 350 aluminum heads,pistons big cam, if you have even more $$ build a 305 to go faster then the 350's but if you just want to low budget add ons how bout a cam, high performance ignition, under drive pulley set, and go carb if you want (something i would never do though my engine loves its tbi well this is pretty long but basically just me talkin and talkin, and this is just an opinion

 

that is so annoying when people say that. for mods if i were you i would go with headers and y pipe and a catback. another easy one is open element, and i would do a tbi chip. if you do not have emissions take the cat off cause that will help a lot with the high end power. i do not have a tbi car but i know three people that have them or have had one and that is what they did and they got some pretty good numbers from doing that stuff. hope that helps!!!!!

 

totally forgot exhaust of course headers and y pipe and cut that cat if you can i gutted my cat and still passed emissions but just recently emissions is gone in my state if your car is more than 14 years old i think i have a pretty cool setup for air induction its a tpi air cleaner assembly with a flexible hose to a carb hat ill post pics when i get my engine back together planned date: some time before last week of august

 

True - and it always gets said, so after 5 years of seeing it, and having an opp to be first, I thought I would - now it's outta my system

But seriously... the 305 is a fine little motor - the issue lies in the ECM, and thus the induction, and not the motor. There's a ton of stuff that can be bolted on to the 305 to make decent power, but sticking with the TBI system was always the problem - the poor little TBI ECM just doesn't have enough parameters to EASILY program to get the performance from the boltons. Unless you have alot of time, programming knowledge, and the patience to do it - it's almost impossible, as the stock ECM will not like but just a few mods, and then it chokes on it - making the trouble not worth it.

I did it all to my 305 - headers, gutted cat, 416 heads ported/polished, 1.6:1 rockers, LT1 cam, VaFPR, one size larger intake valves, Hi flo intake, muffler ... I spent a ton of time and money, and since I could never get a chip programmed, and didn't have the knowledge to do it myself, I ended up with a bunch of bolt-ons that actually made the car run worse.

So - if you have the knowledge, chip equipment, time, and patience - go for it. Or if you can go carbed with the 305, or use a TPI system - carb is easy, TPI at least you can find others to make chips (no one programs chips for the TBI except the TBIchips.com guy, and he sucks).

That's just been my experience. On my 1992, I went carbed 350, and it was so easy, and it's so fun to drive in comparison to the 305 - and the only place for me to go from here is up (more displacement).

Best of luck with whatever you choose.

 

It depends on how fast you wanna go....I've had many 305's and 350's....I have a 305 Tuned port motor that was fun.....but the 305 throttle body injected motor is kinda weak....it might actually be cheaper in long run to do a 350.. put it another way for you.....you have a 170hp. (I believe anyway)...if you did a STOCK 350 TPI swap..245 hp...and TONS more torque.....no to make your 305 tbi have roughly 250hp...heads,cam,intake,chip,exhaust..and it still might not make the torque the 350 turns out.....find a stock small block and go from there....that's my recommendation anyway....

 

The 350 swap is not a bad idea if the 305 is defective. Though you dont need to swap heads on a LO3 to make 250hp. LT1 cam, intake, 3.23 gears, tuned EBL, TPI fuel pump, AFPR, full exhaust, cai and you are there.

 

just a cam, intake manifold, and exhaust is hard to imaging getting 80hp, especially with low compression and poor flowing heads...but maybe I'm wrong...3.23 gears have nothing to do with power though....but gears are a good idea. I had a '91 RS with a 305tbi, edelbrock intake, crane cam (can't remember size)open element K&N filter, heddman headers, flowmaster exhaust, and a 4.10 gear set....best run was 16.5 in 1/4mi....lot of money for not much gained over running a 17.

 

mine was slow....but then again it was kinda beat up back then.....I dunno lo3 as well.....good luck either way though....

 

It does affect power mesurements.


Open element aint no power upgrade on a tbi wetflow manifold. TBI chips and TBI ECM are the LO3's reputation killers.

 

The affect on gears affecting horsepower has been on here before.....a big debate over that.....

The TBI was my first camaro....didn't know what to do to it.....completely different than my build now.....TBI cars are usually slow....but it sounds like you have a handle on how to make them more powerful.... good job......I never did figure it out , lol.

 

read my sig, there you go.
Or read this. I spent alittle time on it. I'm still in the process of tuning it but from what my EBL is telling me I should be in the mid to low 13's as I sit now.
https://www.thirdgen.org/forums/tbi/...-synopsis.html

 

sk8r, the starting point is NOT what you want to accomplish,
but what you're willing to do/spend. Considering emissions
requirements you have to meet, upgrades to the air intake,
and exhaust system are easy & cost-effective. Then you can
consider some upgrades to the manifold/tbi set-up, for which
there is an ABUNDANCE of info available here. By that time,
the limiting factor will be the ECM, as pointed out above.
More extensive upgrades like cams, heads need to be evaluated
in light of overall engine condition/mileage.

There are talented guys getting great results from 305's, but
in my humble opinion, it's a very Quixotic endeaver. If you get
to the point of serious engine upgrade, 350 provides the best
hp/$/effort.

 

thanks guys for all your imput now i just have to choose someones opinion but sadly i won't be upgrading for a while 'cause my maro is dead i'm currently fixing it with some help and it still isn't finished so ya i found out its really hard to take out a 20 year old O2 sensor among other things but thanks anyway hopefully i'll be up and modding soon thanks

 

I'm hoping to do all the bolt-on mods to my 305 .Gust the bolt-ons that can be swapped to a 350 TBI in time.(maybe a stroker). Such as headers, full exhaust, coolers, open element and intake. Stuff like that. Where I live in CA there's only so much you can do and still pass emissions. Any way that's my plan because my little 305 is still running fine for now.

 

may be able to use some of your guys' info now i've fixed my maro and its almost ready to drive

 

It's a CAmaro.