305man

This link is for anyone who wants to learn about the three major forms of fuel injection, some third gen engine history, and most of all why tbi isn't bad and how to improve the performance of your 305. I found this a few weeks ago and I immediately started feeling better about my 91 RS's potential. On the 3rd page at the bottom they have three more links for buildups, the lowest one dynoed at 290 hp. When I finally finish paying for classes I'll start modding mine too. here's the link. Enjoy!



http://www.goingfaster.com/spo/praisetbi.html

Chuck!

Good ol black echo.

Under all the fluff on that page there some good tech, unfortunally its all based on theory like when I bolt this part to this part Ill get xx horsepower. Unfortunally it doesnt really happen that way.

Your best bet for good solid tbi info is on the tbi board on thirdgen.org. There are a few guys over there with some stout little setups. For real life numbers and tech, check out Z28 boy's homepage, z28boy.cz28.com. You can see what I did with my setup but lol... its got a lot of problems now to say the least haha.

Happy motoring, man.

Chris Ja

The man is correct if a 283,302 or 327 can be made fast then why not a 305. There is a lot of fluff on there and not much to back it up. I purchased my 305 TPI IROC in 1987 new and there was very little you could buy to mod the car. Everyone said you could not do this and you could not do that. The first engine I built was a 350 and I used alot of old school parts that were for a carb engine. The car ran high 13.9 but that was a inprovement. On a carb engine it would have been in the low 13.0 or 12.9 Now I have another engine I built after more aftermarket parts came on the market and the car runs 12.9 at 110 MPH on street tires. I have picked up a few more things and now the car should run 11.8 when I go back to the track. Don't let people tell you it can't be done. It takes time and money trail and error but if you don't give up you will get there.

305man

Yeah, I see what you're talking about. The guy was probably excited when he wrote it. But I see alot of fact in it The 305 tbi was purposely restricted to the greatest extent so that the other models with performance parts right out of the factory would seem so powerful. The comparison charts b/w models seem fairly accurate. The first I believe is both factual and motivational. Before I found that site, I was reading other posts where prominent members were completely annihilating the 305 and tbi in general. You can't help but feel down about your car when Chevy Camaro owners are trash talking it. The first page the guy wrote got me over that plus I learned stuff I didn't know before. The setups on the last page (after all the talk before), had been tested and seem very promising. I'll check out the thirdgen.org site as well and see what they've got.

DarthIROC

If you click that other link they have some decent stuff, namley talking sence into people that shun suspension work.

305man

Yeah, when I first went to that other link I thought he'd start talking about exhaust first followed by engine work. But he made very good points, its wiser to work form the ground up (suspension etc.), and that since its a 3rd gen that stuff needs to be replaced anyway. So I guess I'll do some suspension work on mine either shortly before or after I finally put exhaust on mine.

1fastformula

I think I am going to chuck my TPI (on my 350 HO crate) for the NEW king of induction...The TBI

I like the stats he put up....but how can you justify the Cease Fire Injection (on a 350 no less) is better than a TPI 305??? The TPI unit outshined that slug of a 'vette.

To each his own I guess

Later

Chuck!

There really are some stupid restrictions in the tbi. The 2.25" exhaust, along with small exhaust manifolds, peanut cam, 2.73 gears with no 3.23/posi option, and the most rediculus heads ever put on a small block. The throttle ridges around the venturi and fat throttle shafts. Hell they didnt even find it necessary to set a standard fuel pressure on the damn car. My friend greg's 88 LO3 had different fuel pressure than my 91 stock. 1200 stall converter, sad single snorkle air intake. The only problem with moding the tbi is overcomming all the cards stacked against it. Even changesing in timing from 0-6* advance can make a noticeable difference in a tbi equipped car.

The 1 11/16th tbi I just found out isnt even the problem. Under wot my manifold pressure is constant ~94 kpa up though 5500 rpm so even on a heads/cam/intake car the small tbi feeds decently enough.

Thats about my rant for the day lol.

NJ SPEEDER

just out of curiosity, have you taken that crate motor to teh strip yet? i know a lot of the tbi guys are finding great success with it, i was wondering how tpi reacted to it.

later
tim

1fastformula

No track times, but plenty of LT1 kills.....Raced one LS1 and he handed me my a$$. He would not let me look under the hood

I will get track times soon.

Later

Jim85IROC

Every time I see somebody praising the greatness of TBI, there's ALWAYS a link to Black Echo's website! That clown had no idea what he was doing, and dispite his best efforts, he never got his car to run any faster than stock.

Most of the stuff on that site is crap. The fact is, stock TBI sucks. The computer is incredibly primitive and no good for anything but operating a stock tbi unit.

There are aftermarket tbi setups available that have been shown to make just as much power as a good carb or a good MPFI setup on the same motor, but those are controlled by far more sophisticated computers, and are all in all a much better design. Holley's comes to mind. They use the Commander 950 computer to run it, and it's a very high quality piece. One of the recent magazines bolted that, along with a good 4bbl and a Stealth Ram onto the same motor and all of them were within 10hp of each other.

305man

Nobody said tbi was better or worse than any other injection system, the guy who wrote that article didn't even say that it was better or worse than any other system. His purpose for writing that article was to prove that it really wasn't the injection system that held the LO3 back, it was the stupid restrictions made to the single snokel intake and intake manifold, the entire exhaust system with its manifolds, the 273 gears with no upgrade option for better gears w/ posi, the cam sucked @$$. With all that and some it doesn't sound like TBI sucks, it sounds like GM sucks for purposely making the injection system, surrounding it w/ inferior parts and giving the other Camaro models performance parts from factory just to make a difference in the cars. Are you seriously telling me that after replacing all of GM's f##k ups just to give the LO3 the same advantages that the other models did, that there wouldn't be any noticeable difference in output?!? The site is fairly good, he has to speak somewhat highly of the tbi system to repair the damage members such as yourself have done to tbi owners. $hit the forum is supposed to be about helping fellow F-body owners with what they have. Everybody doesn't either want to or can't afford to rip out their tbi system or take out the 305 and drop in a 350. For some members that seems to be the same $hitty advice they give out to these new Camaro owners that don't know any better. Instead of telling them the LO3's were restricted models and helping them with what they have, and then suggesting to them that if they want even more output they may want to look into a 350, you'd rather mock and criticise. I thought the forum in the interest of sharing ideas and helping each other out but I guess not. That's my rant for the day.

NJ SPEEDER

it is so nice to see peopel with such open minds posting, especially when they are obviously sssooooooo well informed.

tbi vs tpi vs carb si a worthless argument, i think most of us can agree on that. any induction system has it good and bad points.

the stock tbi motors were very weak. they were only rated at 170 hp. unlike the preceding hundred years of carb technology that a tpi system that gm poured littlerally millions of dollars just into teh intake development, tbi was pretty much designed for reliable and fuel efficiant useage by people who wanted or needed a little more than a V6 woudl provde.

as a result you can run down a laundry list of parts that held back the tbi cars from teh factory. most tbi cars have 2.73 open rears, most tpi cars have 3.23 posi rears, and most of the carbed v8 's came equiped with 3.08's with or without posi. geee, ya think posi and .6 in ratio makes much of a difference?
then there is one of my favorites, teh exhaust. where tpi cars came with a single 3inch system(with a lame y-pipe) or dual cat system and better manifold castings, teh tbi cars got eh shelf item truck exhaust logs and a massive 2.25inch cat, hmmm, think tha tmuch flow woudl help a bit?
then there is the worst part of teh motor, teh cam. ahh, this laughable little stain on the a$$ of V8's everywhere weighs in at .402 lift at teh valve, teh L98 cam was i believe aroudn .425 with a good bit more duration than teh tbi cam. several people have put L98 cams into LO3's and gained 2+ mph of trap speed.
as far as that "primitive" ecm goes, it samples at teh same rate as teh carb adn tpi ecms, sees only 1 less sensor reading that a MAF powered tpi car, and is beign used to lead development for do it yourself chip burning.
good thing you set us all straight abotu tbi, we will be jumping on teh blind leading the foolish band wagon with you any time now.

for everyoen who wants to keep an open mind about different types of induction, my car knocked off a whole second with free mods, 3.54 gears and posi, and a full exhaust. i was going 15.0's in a 3700lbs car on street tires at 90mph(5mph faster than stock). with that kind of result from common mods, it certainly looks like the stock application does not set the limit.

later
tim

305man

Thank you NJ Speeder, and others who have posted intelligent, replies to this thread. On a side note NJ Speeder, I just wanted to know what exactly were the free mods that you did and howcome your car weighs 3700 lbs. Is that weight w/ the driver? Or did GM increase the weight of the car b/w 1990 and 1991? On thirdgen.org in a comparison between the 69 Z/28 and the 90 Z/28 the '90 Z/28 had a curb weight of 3471 lbs.

NJ SPEEDER

you can find several articles abotu tbi at www.thirdgen.org . the ones taht are going to be of teh most interest are teh ultimate tbi mods parts 1&2 and diy afpr. it woudl also be a good idea to start reading the stuff abotu prom burning so you can get an idea of how it is done form real data instead of from a sheet of paper like the mail order comanies use.
my car weighed a lot because, at teh time, i had a full road racing susepnsion on it. taht included solid oversized sway bars, 17x9 wheels and 275/40 tires. i also have a dana44 rear in my car which is a good bit heavier than the stock 10-bolts and 9-bolts.
my car has gone back to being a drag project and last time to teh track it weighed 3280 with driver and i still had power windows/locks/hatch realease/ and a/c. hopefully it will eb done and back to the track mid summer weighing around 2900 with driver and packing over 400 hp at eth wheels. and yes, i am still going to be runnign tbi

later
tim