Ann.racer92

why was the tbi motor even made? the base motor for the z28/iroc was the lb9 right? and the rs was usually a v6 car. why even interject a low hp mediocre fuelmileage dog into the equation? a dog which had to be bought as the more expensive "cheap" package. the fuel mileage even with highway gears is not significant unless you have a t5 but the lb9 got about the same mileage we get according to tpi guys. consider the mustang. minus the lo3 this is what you get for a comparison in that day in age.
mustang, engine options, 4 cylinder dog or 5.0 that hauls.
camaro. v6 thats faster then 4cyl. mustang. 5.0 tpi that keeps up with the mustang. and 5.7 that blasts the mustang. where does the tbi fit into this?? slightly faster the v6 but with no mileage gains over the truly fast motors of the day and it def cannot keep up with the mustang. wtf?

dimented24x7

iTrader: (2)

Some of the LB9s where fuel injected dogs as well. The purpose of the TBI was pretty much to supply a cheap, low cost fuel injected replacement for the LG4s after they where discontinued. They needed a baseline V8 camaro that was a step above the aneamic V6's but still not so fast that it stepped on the toes of the tpi camaroes. Plus they already had tbi from the pickups so it seems like a logical choice to stick it in the cars as well.

You also have to keep in mind that the camaros are full sized cars that are definatly on the chunky side. A V8 should have been manditory for all NA applications IMO. The mustang I use is a clown car compared to the camaro. Its basically a RWD civic. I can bearly fit in the thing. I can see why people can run 13's so easy in them.

90RS305

And I don't know what your talking about in the "mediocre" fuel milege. I can't name too many V8s that get 22+ mpg on average! Shoot, I got 36MPG on my last road trip!!! And as for not keeping up with mustangs?! I don't know where you get that from! Out of ALL the 80's-ish mustangs that I've raced, only 3 have beaten me, and as I found out later they all had brand-spankin'-new engines. And Dimented said it perfectly as well: "...to supply a cheap fuel injected replacement..."

Bruce (90RS305)

Pablo

iTrader: (1)

honestly, you've only raced 3 v8 fox bodies right?

90RS305

Lol, you caught me...

Z28GEN3

thats the #1 reason i dont have a mustang! no leg room.

cali92RS

I think TBI is cool cuz of its simplicity. No one here is gonna blow smoke up your a$$ and say its performance oriented, but what other fuel injection system can you get complete for the price? And its really versatile and user friendly, especially once you start to get into burning your own chips

costill91Z

Think of it this way, would you want a 4cyl or v6 camaro or mustang, if you wanted to go fast, no. (unless its a tta or a gn v6, or an svo stang) but, if you couldn't afford a v8 stang, or a high end tpi car, then you would want a v8 f body, b/c its up to you to mod it after that. isn't it easier once you have a v8 in the car to beef it up rather than try to do a 4or 6 to an 8 cyl swap. granted stock tbi's are dogs, but, once you start to mod them, they really can wake up, especially once you do tuning, and get rid of the peanut cam and swirl port heads. too many ppl think that tbi's are a waste of time and they are not. yes, id rather have a g92 tpi 5spd, but i don't so, i have to make the best with what i have

buzz12586

Because its a V8!!! You can't beat that sound! I mean my car may be slow but at least it is a v8 and doesn't sound like crap with an exhaust system on it.

80smetalfan

i agree with the thread starter's first post to a degree.

why the TBI was implemented and the LO3 designed was obvious. the ignorant consumer sees "V8" and buys it over the V6. that simple. and i have no problem with TBI in general.

what my beef is about the L03's design is why that crappy of heads and cam. i don't buy the reliability, longevity, gas MPG, etc. crap that i hear all the time.

my 85 suburban is completely stock except for an open element and no muffler or cat, and when my L03 camaro was stock with the same mods, it got worse MPG in town than the suburban did (with a good tune...i spend lots of time tuning). it slaughtered the suburban in highway MPG because of the low gearing of the suburban. and my suburban has just as many miles as the camaro, they're all from towing trailers and boats, and the suburban is more reliable. i've never had to do more than routine maintenance the whole time i've owned it. regardless of if i haven't drove it forever, if it's cold, whatever, the car always starts. it has routine problems like fouled plugs that need to be changed and whatnot, but i've never had to tear the motor apart or even mess with the carberator. so the crappy heads and cam on the L03 don't really add reliability, IMO.

i'm going to try to summarize my argument here:
how pathetic the L03 heads are is inexcuseable for a camaro V-8. inside and outside the 3rdgen fanbase, RS's are mainly mocked and ridiculed for being the slowest v-8's out there. most 4thgen v-6's will take a stock L03. it really would not have been that hard to put decent 58 CC heads on these cars, and a decent cam. just add $600 to the price tag (in today's market...it would have been less during the 80s) and that could have been accomplised, and these wouldn't of been that bad. but just look at a mustang LX 5.0. now granted, it has the exact same motor as the GT, but stock for stock, i think a 305 TBI with decent heads and cam has a fairly good chance of beating it. i don't know. i just think the L03 is just a retarded motor to put into a camaro. a silverado 1500? that's more appropriate. but a camaro? not really. i guess it adds more of a "sleeper" attribute to all of us RS owners, because everyone expects these to be pathetically slow. but other than that, there is nothing that's not extremely retarded about the heads and cam that were chosen to be put in this motor.

Cadillac

I fully agree with the interstate and high speed performance of the 305 TBI for long periods. Efficiency was good too going over ridge to Santa Cruz.

I like that I have 75-80 MPH @ 2100 RPM, 90-95 @3500 and there is another 3K revs available.

24 MPG, some mixed city in there. City perfromance just sucks with all V8's.

And of course... new paint.



Shameless plug. Sorry.

I guess I would be a fan of the L03 TBI.

C.

dimented24x7

iTrader: (2)

Fuel economy is usually inversly proportional to power assuming the cars state of tune is good. I found my stock motor got fairly decent fuel economy. The improved fuel economy is partly due to the crappy top end. Low revving motor that has its peak torque around the area you usually drive in means that itll get good fuel economy.

As far as reliability? Come on, the LO3 cant even make enough power to break itself. Its just too weak. The 305 shortblock could easily handle 350 some odd horesepower or more.

You also have to remember the time that these cars where produced. It was the eighties, the domestic car companies had lost big after the gas crunch and foreign car influx and american cars werent selling well. The tightened emmisions standards before the car makers really had teh technology to make the cars have power and still be clean meant that power wasnt going to eb in the equation for some time. The small block as well as the computer systems in our cars are stone age technology.

Chevy didnt care if it was fast, they just wanted them to sell. A good looking efficient car that had a V8 meant that they could sell alot of them to secretaries and young people that wanted a cheap, flashy looking car. Other car companies where doing similar things.

Unfortunatly, the third gen's time has passed. Now people actually care about performance so the automakers have responded with cars that actually perform. These days it seems like alot of the manufacturers have a 13 second this and a 12 second that out on the showroom floor.

Although I feel this will be shortlived if the gas prices dont stabilize for the long run and continue to rise. No matter how many cylinders it has, if gas is like 5 dollars a gallon and the car makes some power, you wont be able to afford to fuel it.

Cadillac

They are flashy, huh? Yet conservative...

Dicotomy.

80smetalfan

oh i agree it got good MPG. but i don't neccesarily agree about the MPG being inversely proportionate to power. my car is a heck of lot faster with the mods i have now, and i really haven't noticed a drop in MPG at all. that's mostly because of 2.73 rear gears, though.

i don't know. i would have gladly yeilded 3 MPG for 50 HP, a tradeoff that's easily possibly with tuning.

i mainly just am embarassed that GM produced a sports car with 5 liter V8 as late as 1991 that only made 170 horsepower. they might as well just stuck with the LG4, or just stuck LB9's in RS's. LB9's get pretty good MPG with a good tune and the right gears. and they are a much much better starting point for modifications than an L03 is.

but this is all pointless lamenting. it's been said and done for a couple decades now.

dimented24x7

iTrader: (2)

I think the carb would have been way old by the 90's Had to put something a little more up to date in.

As for Lb9's, there are a bunch of those running in the 15's as well. I dont think theyre a much better place to start, either. The TPI has some inherent flaws that make it undesirable for use in performance apps. Mainly the resonance imposed by the 'tuned port' aspect of it.

Ive observed that the fuel consumption seems to be roughly inversely proportional in cars that actually ahve motors that are correctly matched to the car (not like an SUV with a 4 banger). My firend has a turbo celica that gets around 20 mpg. Also has a monte ss with a tpi'd L98 that gets 20 mpg as well. Power is pretty much power. Since power comes from liberating energy by burning fuel it seems reasonable that the consumption of fuel would have a similar relationship. Sometimes having a larger motor can be preferable as it can work at a lower relative power output level and be more efficient then a smaller motor.

The inverse relationship definatly holds up with my 4 cyl. mustang and camaro. Both engines have similar powerbands. Even with my aggressive driving the mustang gets around 22 mpg. The camaro gets around 14-16 mpg, but its obviously much faster then the mustang.

As for thirdgens being flashy, I think they are. And cops definatly think they are.

90RS305

uhg, there's the understatement of the year....

Cadillac

Well, I guess I knew this before I bought the car but DAMN they are beautiful cars. Very unique.

I dream of a 5.7 liter engine with a manual tranny in my car. Then I wake up and realize I would kill myself or end up in jail with that kind of performance.



In a twisted sort of way, I am glad my engine is an LO3 TBI. I'm pretty limited with the mods I can do (short of a new engine) and the power is not enuff to go out of control. At the same time, 200HP is within the realm of reality and could represent a significant performance increase for me.

It's all good.

~C

dimented24x7

iTrader: (2)

It seems like a huge jump at first but it wears off and youll find yourself still wanting more

Big AL91

I love this war(Gen. Patton), TBI vs TPI, 305vs350, stock vs stock and horsepower. To repeat an expert IMHO, tune the 350 TPI , get every HP available, tune the 305 TBI for all the torque available, 305 TBI wins hands down with its lil ole 170 Horses. Got a 305 TBI with poor performance? Your computor would like to tell you a thing or two or more if it could spend time with you , please see that I properly fuction by my indicators and please listen!
Thanks for a good discussion with valuable input. The best!

Cadillac

SHHHHhhhhhh!!!!

I'm still in denial about that.

cali92RS

So your saying a well tuned stock 305 TBI will beat a well tuned 350 TPI? Can you come to LA and share whatever your smoking with me?

Big AL91

THats not what I stated, It depends on the difference in tunes. If you cannot get your HP in Torque that welds your back against the seat and the headrest prevents a neck sprain, then HP must be used by the accessary attachments. Respectfully, never smoked the stuff suggested, nor would I visit LA except for a stopover to The Islands. Respect those whom chose to reside there, but *******s and 69 year olds need to stay closer to home. Meet halfway sometime and we'll have a ___LT. Best Wishes!

80smetalfan

The carb may have been old by the 90's, but what we got was a carb with 2 flow-restricting fuel injectors. Runs better in the winter, but was it really an improvement? Honestly, by this time port injection was all over the place, especially on sports cars. I really cannot think of another sports car from the time that was using TBI (in your defense, I can't think of a car from the time using a carb either, lol ). Even baseline family sedans were using port injection at the time. A carb would have prevented GM from cashing in again on ignorance by throwing the term "Electronic Fuel Injection" onto the motor, I guess.

Yeah, there are LB9's running 15s, but there's a lot of L03's running 17's. I agree, TPI has flaws, but not nearly as many as the stock TBI units. "Yeah, you can get a 4-barrel TBI, but then I can get stealth ram and blow you away", and so a pointless argument begins. I'm talking stock for stock here. I don't get how starting with an L03 car is almost as good of a starting point. When you start with an LB9 car, you have firstly a fuel pump that supports a lot more power, and if you stay under say, 300hp or so, you can usually keep the stocker. You also have a better intake and injection system, you have a lot more torque than you'll get out of TBI, and correct me if I'm wrong, but I'm pretty sure the TPI unit outflows the TBI unit (again, stock for stock) by a longshot in terms of airflow. TPI is in general a lot more desireable for performance than TBI, especially on a 305 which it can feed effectively. Run a turbo on a TPI setup and you essentially eliminate it's main percieved weakness, high end power (though, in your defense, you amplify the resonance problem just slightly..... ). Don't get me wrong, SFI and MPFI are a heck of a lot better than TPI. But all 3 are better than TBI.

But I'm getting away from my main argument. Why the bad heads and cam? Why? Why? Why would you put a truck motor in a camaro? I always have, and always will think it was stupid on GM's part. Yes they are in the business to make money, which was obviously the only intent of producing L03 camaros.

i still disagree about power. you can rod a 2.3 4 cyl. mustang and get 22mpg, and i can rod a 1.6 VTEC Civic (as much as i hate to complement hondas ) and get at least 25 MPG, and probably come close to taking your camaro in a race too (though it's unfair because of shallow gears on the civic and a lot less weight). air flow is everything. the civic has a better head and fuel injection (though the fact that it's DOHC also gives it an unfair advantage) than the ford, thus the better power and economy out of a small


EDIT: whew, Thank *** for cache and the back button. Ill ahve to be more careful not to click the edit button by mistake

Pablo

iTrader: (1)

I wonder how you can say there is no improvement from carb to TBI. A carburetor relies on mechanical inputs to introduce fuel (airflow) and fuel is a more viscous fluid than air so the air can accelerate much faster than fuel hence why carbs compared to FI are unresponsive.

I have actually DONE the tbi, to carb, to tbi swap, and, I have actually tuned the carb to run the times in my sig utilizing a wide band and some less than common tuning techniques.

I can tell you, without a single doubt, fuel injection of any kind, to include tbi is lightyears ahead of the carb. The precise tunabilty of TBI cannot be matched by the carburetor. The low end torque cannot be matched. If you wish I can send you datalogs from my wideband and 13.6 run and you can comparethem to how the tbi performs with those datalogs, there is no comparison, no leaness on the launch, or shifts, no overly rich condition beyond peak hp. I can tune all of that out at the click of a button. The carbs fuel curves are built in. I can make my own with FI.

The one downside is it requires some knowledge and a desire to do the tuning. If you dont have that then you are better off going carb since its gonna be in the ballpark alot easier than the FI will be. But that last 15-20% of performance you wont find unless you invest an insane amount of time into the carb experimenting which you can completely avoid with the wonders of efi

90RS305

:hail: :yourock:

Pablo

iTrader: (1)

oh and one more thing, I know that current formula 1 engines (atleast one that i know of) use TBI.. so theres your "sports car"

80smetalfan

Agreed. And in most cases, you're not going to get the advantages of electronic spark control with a carb setup either.

This would be my argument for going carb instead (as in GM producing these cars with a carb instead). Without chip tuning (as is the case with all EFIs, not just TBI), if you dump the stock heads and cam for better equipment, you're going to have some serious driveability problems. One of the main reasons I went TPI when I got my heads and cam, is I figured if I was going to get into datalogging and chip burning (which I was going to have to do), I'd rather burn the money on TPI which I see as a superior FI choice for Street-strip/daily driver performance setups (but I'm also a torque freak....i like power down low). The carb would have been better for the average Joe, who has his mechanic buddy do the swap and then can do limited tuning himself (distributer timing, idler, etc.). I will admit my view may be slanted, but I tend to see more older SC or Z28 camaros with the LG4 that have done moderate upgrading to the motor than I see RS's with the L03 that have. I personally would take TBI because it doesn't run like crap in cold weather. However, most people would not know how to, or be unwilling to do chip stuff, like I would, so I think carb would have been better for the masses. But it's a toss up. There are plenty of advantages to either side.

.....crap you win. I was too vague....I meant....uh.... sports cars rolling off an assembly line to be street legally driven.

Ann.racer92

this psot grew like a weed while i was away..two comments.

1)the one guy said something that actually changed my mind about this which was about the heads and cam,, there ya go. decent heads and cam and these would be decent cars.

2) i asked around the TPI board to see what they got in fuel mileage and it was actually as good as most of the fuel mileage ive seen in my car and heve seen members post, right around 21-22 mpg with the 5.7. yes the 5.7, which i beleive cam with lower gears then ours stock and is obviously a bigger motor and is yes,, stil getting better mileage!! this is what started my rant in the first place. after that i was going to go TPI with the 350 im building but since then ive decided to go 350 vortec TBI. the bitching camaro article in CPO convinced me..

irocbirdbuilder

I hear it form a good amount of fbody guys out here that the tbi is crap and what not but in reality its not bad. It has the go, and i get everyone going oh man that thing is carbed? I think what i liek about it is everyone thinks its slow and it somewhat is but you throw together the right combo of parts and make it fast adn i liek that part. making soemthing fast that everyone thinks is slow. believe me going form a fairly heavily modded v6 to a stock tbi car there was a big difference. It was liek all the work into the v6 and the stock 305 would have taken its doors bad. I have had many v6 crustangs try and havent touched me infact i have a video of me and my buddy in his v6 stang and me walking away from him, i have yet to have a import mobiel touch it. With tthe right combination of parts and know how these can be made fast, they may not touch a vette or a viper but how often do you really get to run one, i caught a vette one night comign home and hung within two three cars of him and i was happy as hell jsut to still see his car infront of me.

My dads got a 91 suburban 3/4 ton with a 4" lift and its a tbi motor its got 180k on it and he's upgraded all the ignition similar to what i have except he has functional ram air and that suck for being the size of a bus has taken a few stangs over the years. ITs not about them being slow its about making them fast and cool

iggy1991

I like TBI myself. Its very simple to work on and has all the advantages of EFI. I do agree that the LO3 should have come with the better heads or the same as the TPI camaros but with a smaller cam that would have lessined the HP rating of the LO3. I think if it did come from the factory with the TPI heads and GM did the tune I think it would be within a car length of the TPI camaros. I'm personally not scared when I come up to a 3rd Gen z28.

Car companys come out with a bunch of models for each car they make and the RS with the LO3 was just another model to buy and I've seen alot of them compared to TPI camaros.

I also have a smile on my face when I race a new Camaro or something similar and I'm only a car length or 2 behind him. Sure I didn't win but its not like he got away.