On a friends 89 305TBI. Basically stock, just headers and an open element. We replaced the intake with a Holley Street Dominator, used a 600cfm Holley VS, and I gave him my BG 3 port regulator.

He reports the difference is immediate, and very much for the better. We havn't even begun tuning it, this is right out of the box so to speak, and already he can't get over how much it helped. Personally I'm actually a little surprised it had as much gain as it did with the stock cam and all.

We had problems with the aftermarket inline fuel pump he bought, it couldn't pull through the stock pump in the tank. Thats why he has my reg now, I'm going to use his pump since I have to drop my tank anyway for something. That took us hours to work out. If not for that, we would have had it done easily in about 6-8 hours, including 3 parts runs.

Score one more for the dark side
Just FYI incase anyone over here was curious.

------------------
"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

Thats awesome. What did the car run before the swap. Post some times of what it runs now too.(when you get them). It will be neat to see what a simple carb will do for a TBI car.

 

how much is MPG affected, percentage wise? What about stalling? carb cars usualy stall on me.

------------------
-Tas
'89 Formula WS-6
[soon to be Torch Red with black hood and headlights =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

 

Was it worth it? I got some mods done already, and I'm thinking of changing to carb, how do you set up the computer and all? Is it hard? What kind of carb would be good? Do you think I should get a new manifold?

Ethan

------------------
'88 T/A
305 TBI with WC-T5
50,000 miles
Flowmaster 3" exhaust
14" K&N Open Element

 

Ethan like to ask a lot of questions. Hey Jester, there are a couple of people on this TBI board that are interested in a TBI to Carb swap. I know u used to have a tech article or something like one on all the parts u needed and what u had to do. Think u could post it? I want to swap to carb when I buy my crate engine.

------------------
Eric Natzke
91 Firebird 305 TBI

ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-180 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone-Free TBI mods
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html

 

Ethan like to kick Mustang butt

 

im sorry guys but to me a tbi to carb swap is pretty stupid IMO. If u need more fuel get a high cfm tbi unit. With carb i can only imagine the loss in throttle response. But hey its ur cars so do what u want. Just commenting

------------------
1989 pontiac firebird
bright red exterior(just repainted)
grey interior
5 spd
305 TBI (stock)
WS.6 formula wheels
3.73 posi rear end
http://members.aol.com/j007golden/Mikey89.html
-------------------------
1985 trans am
factory bright yellow
4 wheel disks
16 inch wheels
305 TPI
power antenna and mirrors
t tops

 

Isnt TBI kind of like a carb, just electric?? A carb has jets(injectors) on top of 2 or more throttle bores, and TBI has injectors on top of 2 or more throttle bores. To me they are pretty much the same.

How do you lose throttle response from one to another? Just curious

 

Carbs need engine vaccume, EFI engines don't nearly as much. TBIs have one out the sharpest throttle responses out there.

 

Especially with PROM mods!!!!!! I am kinda new to the GM ECU/PROM thing but have ton of EFi and engine experieince. I have been truly amazed at what can be done/I have done with my 7747 ECU. You are only limited by your imagination, money at hand and time/patience. And for me, two kids, a wife and a job, too.

 

Damn..I leave my computer for a couple hours and have a million questions I'll see what I can answer.

The tech article is still in the tech article section of this site. It should answer any questions about doing the swap itself.

He's been driving it for 2 days, and it hasn't stalled yet.

I have personal knowledge of 3 TBI to carb swaps so far. One lost 1 mpg, I lost 2, this latest one was just done so no MPG figures yet, but I imagine it will be similar. In fact I'm pretty sure of that since it's the same carb I used and lost 2mpg with. I later upgraded to a 650 doublepumper.

All 3 of us are thrilled with the performance increase over TBI that we got. I'll just leave it at that

There are no before OR after times for this car. I have some for mine, but I also did some other things so they are pretty useless for comparing.

------------------
"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

But throwing a carb in place of the TBI wouldn't that make it an LG4 (82-87 carbed motor) And lets all say LG4 Camaro's and Firebirds are SLOW !!!!!!!!!!!!!!!!!!!!!!!
If there is such a BIG improvement lets see some 1/4 before and after times.I know of someone who took a TPI set up off in place of a Carb and letsc just say that car is now the SLOWEST IROC i've ever driven the car did 14.80's all day and now do 16.00's so you tell me

 

thank you sharp89rs. finally someone who is thinking sensibly.

 

Yep, EFI is not for everyone. It does offer its advantages but a poorly tuned efi setup is no better than a poorly tuned carb. Having a fast carbed car can be about as easy as picking up an intake, distributer and carb with the manufacturers suggested jets. This will get you as close as a manufacturers "custom chip"... simple yet still not perfect solution.

 

Your gonna tell me, that guy lost all the 1.2 seconds by swapping from TPI to Carb? Yeah dude. It isn't the carb, its the guy who installed and tuned it then.
No,the carbs on the LG4 were computerized carbs,not real carbs and I beilve they had restricted cfm too, can't remember what, maybe 400cfm like our stock TBI's are. Carbs and computers don't get along and the LG4 is a perfect example.

[This message has been edited by 91Bird305 (edited January 16, 2001).]

 

I love how everyone on this board always stands behind what they own or what they read about in a magazine and want.

TBI was developed for better emissions. Nothing else. GM would have probably stayed with the Quadra jet they'd been using since the 60's if they could have. The quadra jet at least was a performance carb.

From reading thru these posts I doubt many of you pro tbi till you die guys have ever even driven a tuned LG4 car.
I had my 83 for 3 years. Had 75,000 miles when I got it. I live in South Dakota, if a car is in any way independable or susceptible to failure, it'll fail here in the winter. My LG4 never failed to run right on a dark cold 20 below morning. Even after running the gas tank dry, it restarted with a can of gas. It hardly ever stalled... The only times it did were when I was using the stock LG4 aircleaner and got on the gas too hard. During the time I had it I never had a chance to modify much but with only a noncomputer controlled quadra jet and vacuum advance HEI it was as fast as any RS I ever pulled next to.

Don't knock it till you've tried it guys. My TBI gets horrible gas mileage, has weak performance, has hard starts, etc... I'd take my old low tech LG4 anyday.

------------------
Drew
The lone Thirdgenner of the Apocalypse
predatorman@hotmail.com
My Website
87 Iroc
91 Formula 14.3@98mph
91 RS Convertible
91 Firebird V6
92 S10
98 Grand Am GT

 

Your gonna tell me, that guy lost all the 1.2 seconds by swapping from TPI to Carb? Yeah dude. It isn't the carb, its the guy who installed and tuned it then.


no, its becouse he ripped off his TPI (something the motor was designed to run with) and threw on a carb. He probably had the same mind set as alot fo people in here and that is more fuel more power and thatss the farthest thing from the truth. Eric if its so unbelieveable than get rid ur tbi set up(u know u want to) and switch to carb. Tune it urself so there is no excuses on y its runing poorly. GM took a stab at carb once. Do u ever see it on n e performance car of today?? didnt think so.


No,the carbs on the LG4 were computerized carbs,not real carbs and I beilve they had restricted cfm too, can't remember what, maybe 400cfm like our stock TBI's are. Carbs and computers don't get along and the LG4 is a perfect example.


no they get along just fine. My father has a mint 86 trans am with an LG4 and runs smooth as can be. My TBI would run circles around it though. Throttle response is way better in a fuel injected car. BTW what do u think hacking the computer will do??? 50hp??


------------------
1989 pontiac firebird
bright red exterior(just repainted)
grey interior
5 spd
305 TBI (stock)
WS.6 formula wheels
3.73 posi rear end
http://members.aol.com/j007golden/Mikey89.html
-------------------------
1985 trans am
factory bright yellow
4 wheel disks
16 inch wheels
305 TPI
power antenna and mirrors
t tops

 

Gee willikers dem carbs suck man. Dats why de use dem in pro stock cars. cuz dey beso poor. dey go too fast with a TBI on there. I mean they might break a sound barrier or sometin right?
that wouldnt be safe.
i guess I will stick with TBI because its superior.

 

These are the biggest problems we always haev with this type of debate. No one wants to hear that there is a better setup than theirs. I guess we are all just gonna have to deal with the fact that this is going to be a never ending fued.

 

Just because the engine came with that injection system doesn't mean its the best for that engine. He probably lost 1.2 seconds because he did what u just said. Threw it on and didn't bother to think which cfm would be best or how to tune the carb properly. No one looses 1.2 seconds by switching injection systems.
I don't need to switch to carb at this point. The engine I have now doesn't need any higher cfm than it does. It doesn't put out 250-300hp. If it did maybe I would swap in a 670cfm tb unit. But when I am pushing 400+hp I am not going to have TBI on that engine. 670cfm just won't cut it and I ain't gonna throw on dual tbi's. Thats just asking for trouble.
If GM could I guarntee they would have stuck with carb. Maybe they would have eventually converted to TPI but carb would have been around a lot longer if it wasn't for emmision laws. Not because TBI pushed it out of the picture.

I agree with Tom (COBRAKILLER), this is a pointless subject on this board. There are a lot of die-hard tbi'ers who wouldn't give up their tbi for anything and would spend years trying to build and perfect their tbi to prove everyone wrong.

[This message has been edited by 91Bird305 (edited January 16, 2001).]

 

Well it was my car that me and Jester did the convertion to last weekend (thanx btw J) and I'm happy with it... sure I'm not gonna get the same mpg, I know I'm gonna drop 2-3 mpg but thats life.
The take off isn't as fast at the moment but the carb isn't fully turned yet and I'm still using the stock rear end (2.73). But the mid to high end isn't even compairable to what I had before..
Example....
When I get off the highway to come to work there is a good strech of road and never any cars on it. I always push it on this road. With the TBI I would get to about 70mph before I had to brake for the next corner. Today with the carb swap I was hitting 85-90 mph.
Thats a 15-20mph difference... so yes I'm happy with it and I still have to get the new cam in there next month

 

ok, not this again

[This message has been edited by Duke (edited January 16, 2001).]

 

Gee willikers dem carbs suck man. Dats why de use dem in pro stock cars. cuz dey beso poor. dey go too fast with a TBI on there. I mean they might break a sound barrier or sometin right?
that wouldnt be safe.
i guess I will stick with TBI because its superior.

ya i guess becouse its in prostock cars its something u want to do with a stock 305 huh


These are the biggest problems we always haev with this type of debate. No one wants to hear that there is a better setup than theirs. I guess we are all just gonna have to deal with the fact that this is going to be a never ending fued.

thats not true at all. I have 3 third gen firebirds in my family right now. 1 carb, 1 TPI, and one TBI. I am only saying what i feel is better.

I don't need to switch to carb at this point. The engine I have now doesn't need any higher cfm than it does. It doesn't put out 250-300hp. If it did maybe I would swap in a 670cfm tb unit. But when I am pushing 400+hp I am not going to have TBI on that engine. 670cfm just won't cut it and I ain't gonna throw on dual tbi's. Thats just asking for trouble.


exactly y i think that the switch for carb was stupid for the guy. A basicly stock 305 and someone threw on a carb thats just going to feed it to much fuel.


If GM could I guarntee they would have stuck with carb. Maybe they would have eventually converted to TPI but carb would have been around a lot longer if it wasn't for emmision laws. Not because TBI pushed it out of the picture.


thats just pure speculation. that doesnt hold for much. bottom line if GM thought carb was faster or fastest than y isnt it being used on the LS1 powered ram airs??? I guess if u throw a 750 double pumper on it u will drop .5 in the quarter huh. ya hacking the computer is worht another .3


The take off isn't as fast at the moment but the carb isn't fully turned yet and I'm still using the stock rear end (2.73).


no offence but that just sounds like an excuse for the loss of throttle response. Funny how u werent complaining about ur gears with the stock TBI unit.

 

You are one of the few exceptions to what I stated. The majority of the people on here just favor what they drive, and dont look at the reality of it all. If your TBI car runs better than your TPI car then you might want to send the TPI car in for a tune-up.

 

It wasn't an excuse... I was just saying what I was going to do to solve the problem.

 

well i havent drivin my tpi car yet considering the fact that i just got it like a week ago and it is in the middle of the winter. I do however know that my TBI car would run circles around my fathers carb trans am.

BTW yam thats great that ur telling us about ur problem but if u never switched to carb it wouldnt be a problem. I still dont see y u didnt attack a smarter mod other than a swtich to carb. but thats just me.

 

You know, the biggest gain probably came from the intake manifold. Im not familiar with it, but I am sure that it flows much better than stock and freed up a few horses and that is the difference that they noticed.

 

Hey, I think he did a smart mod. Any mod that gives ya 15-20mph more than the old injection system is awesome. And GM uses TPI now on the LS1's for emmision Mike. Thats why they use TPI. It can pass emmisions and doesn't have to be restrictive.

 

It does not sound very valid to me?? He has no times to base this on. I have a similar stretch around my house, and I get different speeds all the time. Just depends on what speed you are doing when you tromp on it, or how daring you feel before you start to break. Im not saying he didnt get a performance gain, but 15-20mph is alot.


[This message has been edited by Godti (edited January 17, 2001).]

 

Well we will see when he runs it. That will anwser some questions.

 

Will this ever come to an end?! Truthfully, I don't see the point of using a carb. If carbs are so good then why do people with older muscle cars want to swap their carbs for fuel injection? Why bother fooling around with jets and all the other 1001 adjustments a carb has? So you can get worse gas milage and harder starting? You can modify a TBI to work better then a carb, their computer controlled, a lot simpler, and more economical! Everyone says they see an improvement when swithching to a carb, that's because your replacing a stock TBI and intake manifold with a higher CFM rated carb and superior intake manifold, theirs no comparison! If you want to know the truth, then take a 305, put a Holley 670 TBI on there with a good aftermarket intake manifold, and compare it against a carb on the same manifold. That's the best way to solve this.

 

Thats the point that I was making. I think the only reason to go to carb is if you want a 350-400hp+ engine or a highly modded engine that the holley TBI wont even be enough for. I really dont think that it is necessary on a mild 305, but he could be preparing for down the road with alot of future mods.

 

I just have to throw my two cents into this one...Drew, I have to disagree about the LG4-L03 comparison. I owned a 1983 Camaro back in high school with an LG4 305/auto and it was pathetically slow. I now have a 1992 Camaro with an L03 305/manual and it is WAY more powerful than my old '83. Granted, neither one of these cars is about to set any quarter-mile records, but the TBI car is definitely faster. BUT, that's just my opinion.

------------------
1992 Camaro RS
305 TBI, 5-Speed
K&N open element, Hooker exhaust
http://www13.brinkster.com/scbaeb/camaro.html
scbaeb@hotmail.com

 

Hey, I think he did a smart mod. Any mod that gives ya 15-20mph more than the old injection system is awesome. And GM uses TPI now on the LS1's for emmision Mike. Thats why they use TPI. It can pass emmisions and doesn't have to be restrictive.

again i say eric if its such a smart mod than y dont u drop a carb on ur nearly stock 305 as he did. TPI isnt specifically made for emissions. Its a more efficent power produceing injection system. If carb is so good that y wont SLP put it on thier aniversary firehawk??? I mean thats strictly about power and emissions arent at the top of thier head.


It does not sound very valid to me?? He has no times to base this on. I have a similar stretch around my house, and I get different speeds all the time. Just depends on what speed you are doing when you tromp on it, or how daring you feel before you start to break. Im not saying he didnt get a performance gain, but 15-20mph is alot.


I agree 100%


I just have to throw my two cents into this one...Drew, I have to disagree about the LG4-L03 comparison. I owned a 1983 Camaro back in high school with an LG4 305/auto and it was pathetically slow. I now have a 1992 Camaro with an L03 305/manual and it is WAY more powerful than my old '83. Granted, neither one of these cars is about to set any quarter-mile records, but the TBI car is definitely faster. BUT, that's just my opinion.

exactly what i am trying to say. If carb was so great than y did gm replace it with TBI?? and on top of that with thier switch they gained like 25 hp and 10 ft/lbs of torque. So much for power produceing carbs

 

Hey, I think he did a smart mod. Any mod that gives ya 15-20mph more than the old injection system is awesome. And GM uses TPI now on the LS1's for emmision Mike. Thats why they use TPI. It can pass emmisions and doesn't have to be restrictive.

again i say eric if its such a smart mod than y dont u drop a carb on ur nearly stock 305 as he did. TPI isnt specifically made for emissions. Its a more efficent power produceing injection system. If carb is so good that y wont SLP put it on thier aniversary firehawk??? I mean thats strictly about power and emissions arent at the top of thier head.


It does not sound very valid to me?? He has no times to base this on. I have a similar stretch around my house, and I get different speeds all the time. Just depends on what speed you are doing when you tromp on it, or how daring you feel before you start to break. Im not saying he didnt get a performance gain, but 15-20mph is alot.


I agree 100%


I just have to throw my two cents into this one...Drew, I have to disagree about the LG4-L03 comparison. I owned a 1983 Camaro back in high school with an LG4 305/auto and it was pathetically slow. I now have a 1992 Camaro with an L03 305/manual and it is WAY more powerful than my old '83. Granted, neither one of these cars is about to set any quarter-mile records, but the TBI car is definitely faster. BUT, that's just my opinion.

exactly what i am trying to say. If carb was so great than y did gm replace it with TBI?? and on top of that with thier switch they gained like 25 hp and 10 ft/lbs of torque. So much for power produceing carbs

 

[quote]Originally posted by 91Bird305:
[B] Your gonna tell me, that guy lost all the 1.2 seconds by swapping from TPI to Carb? Yeah dude.

What are yu saying i'm making this up? Think about it Go out and by a lets say 88 corvette with a TUNEPORT 350 in it take the tune port off and then tell me "How Good it runs" with the tpi set up off..All i'm saying is i've had tpi cars lg4 cars and tbi cars doing something to an engine that it wasn't designed to have done to it is RETARDED and pointless

 

Actually, the engine has to pass emmisions in order for them to produce that car. So yeah, it is at the top of their list and TPI is the best way to get hp out of an engine or that engine and still pass emmisions. Why is this an issue?

Ok, I take the TPI off and throw something else on with equal cfm. It will run the same. Just different technology. But if u throw something on there that has a totally different cfm than the old injection system and not properly tuned then u will loose lots of time cause ur drowning or starving the engine. Thats what I was saying. I can use a 400cfm tb unit and throw on a 400cfm carb and the swap will gain nothing because there exactly the same cfm, just different injection systems.

And Mike why do u keep comparing the LG4 carb to TBI? First off the LG4's carb is computer controlled, practically the same has the TBI unit. TBI is limited to carb. Carb can go all the way to 1000cfm and beyond. TBI can only reach 670cfm from what I have seen. Thats what I am saying. If you want to build a big hp engine then I would use carb.

[EDIT]
Well my good freind just informed me that Holley makes a 700cfm tb unit. Just wanted to clear that up.

[This message has been edited by 91Bird305 (edited January 18, 2001).]

 

Actually, the engine has to pass emmisions in order for them to produce that car. So yeah, it is at the top of their list and TPI is the best way to get hp out of an engine or that engine and still pass emmisions. Why is this an issue?

so what r u saying that carb cant be emissions legal and produce power?? Some injection system

Ok, I take the TPI off and throw something else on with equal cfm. It will run the same. Just different technology

ya ok go drop a carb (any cfm u want) on a new vette or trans am and u tell me what happens. If u dont think injection systems affect throttle responce and power than u need to go read a haynes a little more.


Thats what I was saying. I can use a 400cfm tb unit and throw on a 400cfm carb and the swap will gain nothing because there exactly the same cfm, just different injection systems.

aright so u dont think there is a varying performance difference between the 2?? If carb is so great it shouldnt matter the CFM as long as thier the same as the swap right? if its fuel u need do it right and get a higher cfm tbi unit. Thats how its supposed to be done. U dont rip out the computer, pull the tpi system and expect a mechaninally operated carb to make power. Trust me i have been through this. My father did the exact thing ur talking about on his old 82 trans am. He hacked the computer and threw in a 350 carb. The car was nothing compared the the stock cross fire 305, and thats not becouse he didnt know what he was doing its becouse its a dumb idea.

And Mike why do u keep comparing the LG4 carb to TBI? First off the LG4's carb is computer controlled, practically the same has the TBI unit

first off i am compareing the 2 becouse one is carb and one is TBI. Both went on f bodies and one came off (at the time). If tbi and carb are so ideantical than y is the TBI car faster and more powerful?

. TBI is limited to carb. Carb can go all the way to 1000cfm and beyond. TBI can only reach 670cfm from what I have seen. Thats what I am saying. If you want to build a big hp engine then I would use carb.

you just contradicted ur self by saying TBI is limited to carb and than by saying that carb has so much more potential. Watch what u say man. SO what i am to understand now is becouse they make a higher CFM carb than TBI unit carb is better?? i doubt it If ur making a street motor and its dumping 1000 cfm into that motor than watch what happens to ur gas mileage and performance. TBI is more than enough fuel for most street/strip applications.

 

Some people need to learn how to quote properly. I cant tell who's comments are who's! Use around the text you're quoting so its easier to read.

 

ok sorry, my fault

 

Dude....Your going to quote anything I say and proclaim "thats wrong" No, Carb is very hard to pass emmisons. That is what I am saying, why do u have to quote that? I never said it didn't produce power. Just said it is not meant to pass emmisions and thats why they don't use it anymore. I agree that there will be different throttle response with different injection systems but throttle response doesn't have u loose 1.2 seconds in the 1/4. And don't start saying the 305 TBI was so much superior to the LG4. There was only a 5 hp difference between the two. That is nothing to brag about. If TBI is more than enough than why isn't it on any of the drag cars or prostock cars? Just curious. Don't they use carb? And why did GM give up on TBI for performance? Maybe cause it was never made for performance? Just like the LG4 computer controlled carb. It was meant for emmisions, not performance.
You are one of the DIE HARD TBIers me and Tom talked about. You'll never give up TBI. You will always think it can outdo any other injection system on anyother engine. And whenever anyone makes a small negetive comment about it, you will blow up with your confusing quotes and responses.
Let me clear this up.
TBI CAN be used for high hp engines from things I have read on here but from people have I talked to OUTSIDE the TBI ring they do not reccomend it for high hp engines. Sorry but I am going to listen to the mechanics that have been in the business their entire lives and go with what they say since they have been there and built them. Sorry.

 

there is very little logic in anything anybody has written. you all need to take a philosophy class, a debate class, a writing class, and a logic class. valid and true are not the same thing, and there isnt even much of either here. Its all subjective opinions and ego involved bs. How bout we start presenting FACTS. and until somebody proves with numbers that an EXACT fuel and air flowing carb is somehow superior to a tbi, i am not going to even read another post, and ill consider letting others post such bs as above. There was very little TECH written above. A better system? Direct Fuel Injection. Till then, i dont think there is a BEST, all have their advantages in areas.

 

well I liked what I wrote on another post but it fits better here :

with all this carb to TBI talk and vice versa, the test subjects always seem to be hoped up with full exaust and intake at least. what if someone tuned the TBI for ALL this added air before the carb swap on the same intake. I bet the change will be ZERO.

If you run a stock TBI orignaly tuned for **** exaust and a 1" x 2" intake snorkel on a car with full exasust and open element of course a carbed car will have an improvement.

------------------
-Tas
'89 Formula WS-6
[soon to be Torch Red with black hood and headlights =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

[This message has been edited by Tas (edited January 18, 2001).]

 

I thought we were missing something around here. Welcome back Nic

 

The biggest TB you can get for TBI is a holley 900cfm 4bbl throttle body. That will handle most anything you put under it.

Zac Spalding

 

The best Idea I've heard all day.
I could start a dozen threads on different topics but let me start with these few here.

First lets address the reason GM went with EFI... specifically TBI. Because it (efi) allows better engine control than non-efi. This includes both fuel spark control. Exact control of your entire spark curve will allow better power, driveability and gas mileage. Add a knock sensor and you can get even more aggressive with your curves w/o fear of people running cheep gas and detonating their engine to death.

Now add that same kind of control to the fuel system and you now have precise fuel flow at all rpms and loads... Carbs do not deliver the correct amount of fuel at all rpm points due to venturi issues... at least not the ones you buy off the shelves (I'll get into that in a second).

Add an oxygen sensor and suddenly you can make corrections to fuel for altitude, weather conditions fuel system wear, etc... results are better gas mileage.

Why TBI? TBI offers the EFI advantages above and is simple to design and mass produce, reliable, easily serviced and inexpensive in relation to any multi-point system. In factory trim, a TBI car is designed as a well matched group of parts that is conducive to great reliability and gas mileage. GM designed it this way on purpose. Tire blazing performance was not on the list for this package... that was saved for their high end TPI package. Can TBI make power... yes, see EFI Advantages.

Whats so great about TPI? For the first time, its possible to package very long runners to enhance airflow and torque in specific RPM ranges. Imagine a 26" long tunnel ram with a carb on it, laughable.

What about carbs. A carb is the perfect way to deliver the incorrect amount of fuel at almost all times. A carb is a kluge of band aids to make an imperfect system work. And it does work... with over 100 years of engineering how can it not. Despite the millions of hours invested in carbs they are still not perfect because you would have to engineer a different venturi for every motor to even get in the ball park. Not gonna happen.

Are our current EFI systems perfect? No way and they still have a long way to go. But even without 100+ years of engineering they do things a non computer controlled car could never dream of.

This is not meant to slam carbs. I respect Carbs. Carbs are what they are and they will remain a viable way to make power for a while but they are in almost every way inferior in operation to EFI... in some ways only slightly in others drastically. Some people may not have the aptitude to install and tune EFI and thats fine. If your one of those people and cant afford to have it done for you, install a carb and you can still be part of the go fast club (and I'll be happy for you) because like well tuned / designed efi cars, well tuned / designed carbed cars are fast.

Now on racing... Dont even try to say that because an 1800 hp drag racer uses a carb its what we all should run on the street. Come on... lets keep it apples to apples people. Who here is going to run a pro stock car on the street? Hands? Anyone? ....thats what I thought.

 

Thanks Dan for clearing that up. That helped me out a lot. No thanks to Mike's babbling. Sorry about the LG4 number mix up. I confused the tq numbers with the hp numbers.

eric/edited post. --snflupigus

I think Dan's post has pretty muched summed up this thread. Carb can work,TPI can work,TBI can work, and they all have thier flaws. Choose wisely and have fun. Thanks Dan.

[This message has been edited by 91Bird305 (edited January 19, 2001).]

[This message has been edited by snflupigus (edited January 20, 2001).]

 

I agree. Do whatever you prefer, but don't say it's the best cause you got it. I haven't been on this board for a long time, but I can tell Eric is fed up with his engine. He expected a performance engine, not just looks. Once he got to know his engine, he realized it's not good enough to run against supercharged LT1s and LS1s (I like the Twin Turbo setup the best, blackhawk's). It's his opinion and decision, and I respect it. ONce he'll get his ZZ5 setup, I'll bet he'll have a better chance.I'll probably stick with TBI, but I still haven't figured out how to make 300+ horses with it, and if I won't, I'll probably go with something else. By the way, Can it be supercharged?

Ethan

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'88 T/A
305 TBI with WC-T5
50,000 miles
Flowmaster 3" exhaust
14" K&N Open Element

[This message has been edited by ethan71 (edited January 19, 2001).]

[This message has been edited by ethan71 (edited January 19, 2001).]

[This message has been edited by ethan71 (edited January 19, 2001).]

 

Thanks Ethan and that ZZ430 swap isn't going to be for awhile. Just learned its gonna cost be a pretty penny to do. And yes u can use a blower on a TB unit. Someone on here has one.

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Eric Natzke
91 Firebird 305 TBI

ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-180 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-MSD Cap & Rotor-MSD Blaster Coil-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone-Free TBI mods
http://members.aol.com/j007golden/91firebird.html
For info on certain parts or mods go to the site below
http://members.aol.com/j007golden/modeval.html

 

The L03 and the LG4 are practically the same thing. The TBI roller cam probably gave the L03 a little more power but they are still basically the same thing. TBI vs Carb, TBI better for over all emissions than carb, both have their good and bad points.

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1989 Pontiac Firebird
Formula W6S LO3 TBI 305
-180 degree stat
-Hooker Cat-Back

1985 Camaro IROC-Z LB9

http://www.geocities.com/krt80/