costill91Z

ok, i am involved with an argument that tbi sucks, i explain that it is more the fault of the fact. tune, cam, heads and manifold.
so what are some of the fast tbi times?
i would like to prove a point that tbi doesn't suck, so people dont just say go tpi, or go carb its better
thanks for your help

vjo90RS8

iTrader: (1)

14.791 @ 91.11MPH with mods in sig minus tranny, 2400 stall TC, and intake manifold. The times are with stock tbi, stock heads, stock camshaft, stock manifold, and a tbichips.com basic mailorder chip. Im hoping to make it to the track this weekend to see how the car does with the torque converter and edelbrock intake manifold if it doesnt rain.

Gunny Highway

iTrader: (1)

I'm somewhere in the 13's, but I have bald tires and I'm still on the first chip burn. I've also got some 1.6 RR's to go on as well. Most likely will see 12's when it's all said and done.

ShiftyCapone

iTrader: (7)

TBI has great potential. The reason why you do not see a lof of fast TBI cars is not because of the system but instead how it is set-up. Many people throw heads and cams on these motors that are poorly matched. On top of that they leave the stock chip in which keeps them dead in the water. They get mad, and go carb ro swear off TBI because they didn't take the time to fully understand it and learn to properly plan, install and tune a combo. For every one person that does it right there are a thousand that do it wrong. People will bash it because it is easier than learning it. Unfortunately society works that way in all realms of life. Word of mouth spreads and then the next thing you know everyone hates it and writes it off. 99% of all TBI haters don't even understand how their system works. They don't realize that these motors came with weak everything.

We understand that this system has its flaws and its limits but one has to put that into perspective. This system was never intended or desinged to make huge HP numbers or run boosted power adders. It was desinged as a torque oriented powerplant to power a fleet of GM vehicles. It was cheap fuel injection. However, it is just like any other system. If you know how the fuel and air delivery work you can make power until the design of the system becomes the limit.

Just look at guys like Dewey who really know TBI. 14.5 with a cat-back , open element, 3.42's (changed his MPH but not ET) and chip work.

Fast355

iTrader: (2)

Old Combo:
14.95 @ 90 in a full size van with a TBI 350, 601 HO 305 Heads, F-body LT1 cam, edelbrock intake, Ultimate TBI mods, and headers (note factory chip, 6* advance, and 15.5 psi fuel pressure)

New combo has not been checked but feels stronger

TBI 355, Ported 193 swirl ports, F-Body LT1 cam, edelbrock intake, Ultimate TBI mods, headers and DIY chip tuning.

Still have a posi 3.08 rear gear and a 700r4 with a 2,000 rpm stall. That is with a 275/70/R15 tire too. I am geared taller than most of you.

SchwarzCamaroRS

im looking for mid-low 14s with my setup in a couple months.. one day ill get into the 13's, no spray... just dont have the money right now.. lol

90RS305

15.3 BONE STOCK Granted not the fastest car in the world, but perdy dang good for a 3500lb+ sled with the lowest powerd V8 to grace a bowtie...

Bruce (90RS305)

Dewey316

I'm gunning for 12's this year.

MrDude_1

if you're saying it doesnt, you're on the wrong side of the argument.

regardless of anything else, you cant get injectors big enough to support good horsepower (good by modern standards, not 1980s standards)


now, if you're just after how much as someone tweeked a car to take full advantage of its limited power to go the quickest in the 1/4 mile.. id say 12s for a avg weight street/strip 3rdgen.



edit:
thats high12s btw.
and on a tweeked out car.
the only thing making it so its not a 13 second car, is the fact that the CAR ITSELF is tweeked for the strip.. not the TBI making more power.

Ronny

iTrader: (1)

first set up 222 RWH at 5000rpms. 12/1 A/F. 90 deg F 90% humidity. new set up will spin 5500-5800 rpms with new cam and different manifold and better tune. will put on dyno(same one) and check result this spring.

Fast355

iTrader: (2)

90 lb/hr injectors at 30 psi will support more power than one would think. I can drown a 300 hp 350 with 90 lb/hr injectors at 13 psi during ae @ 4,000 or so rpm.

BMmonteSS

I've run a 13.9 @ 97 mph with 70 pphr injectors at 21 psi. I've got tons of room to grow, 12's aren't out of the question. Jon Prevost has run a 13.6 @ over 100 mph, he's only running 65 pphr injectors. With 90 lb'ers over 400 hp is possible. I'll be conservative and say that TBI will support 375 hp at the wheels, that should put the average 3rd gen in the mid to low 12's. TBI has limitations, but like any system they can be tuned around.

JPrevost

Well I just got a deal on a 4th gen rear so I'm going to put slicks on this rear and get the red sled into the 12's if it means stripping the interior, so be it.
After I get that goal I'm putting the car back into street trim. I figure there needs to be a TBI 330ho crate motor in the 12's after all these years .
I also might have a T5 coming my way which will definatly help.

Gunny Highway

iTrader: (1)

Should be there by the end of the year.

Who wants to help me with chip tuning (hell, I'll take help with datalogging at this point )










seriously

heavychevy454ss

I'm looking for 12's in a full size truck with 489ci. I believe VA454SS is running low 13's in his truck.

The TBI can fuel just about any street small block & most street big blocks.

costill91Z

well, the way i look at it, and, correct me if im wrong, but if you took an L98 or LB9 long block with a tbi set up w/ free tbi mods, a decent intake manifold, and proper computer tuning, wouldn't they make about the same power as their counterpart using tpi? that was kind of the point in my argument, and is why i have not ripped the tbi off and put on the tpi setup i have laying around

MrDude_1

no.. it wont.

and for all the arguing that the pro-TBI people will give for it... i dont have a exact reason why.


but my proof is, alot have tried, and noone has done it yet.

Dewey316

its going to have a diffrent powerband.. yes.

you lose the helmholtz tuning of the TPI, so you won't see the 'Peak' toque number.

Mr_Dude, who has done it, had it tuned properly, and had dyno numbers. have they taken the exact same car, switched it to TPI, and gotten numbers on a dyno with that?

In theory (I have not done this) the TBI should make a higher peak HP, and TPI will make more mid-range torque, and likely a higher torque peak.

I will also add, using a STOCK Lb9, is not the right choice for TBI, the cam used, is set to make peak torque, right at the TPI sweet spot with the resonance tuning, this is not a good combination for TBI. If you toss a MILD performance cam, that moves the powerband to where it should be to take advantage of the upsides to TBI, it will outshine stock TPI in the exact combo. Doing a stock LB9 or L98 comparison is not really fair, you are using a cam tuned specificly for that application, along with tuning for that application.

MrDude_1

i agree with everything you just said.

like i said, i have no proof as to WHY...
WHY i donno.

it has more CFM then a carb... and you could bolt it on inplace of one..

so i cant answer the WHY it makes less power.


ive only seen the end result.... you know what you've done and what you know about TBI.. you've played with it alot.. and you know your results arnt typical.... but even if they were, im sure you also know you could make more power with another fuel/induction system.

why? i donno.. id be intrested to find out.

but the results are there...

Dewey316

I think the big key, is tuning. very few people have a properly tuned TBI vehical that has been modifed. The ones that do, have good results.

Look at what JP has done, he is making more power than GM delivered with that motor, and a carb.

The people who have built motors to let TBI potentialy shine, have given up, and gone to carbs before the motor had even a descent tune. This is why they are seeing the big gains. Tuning a carb involves turning screwdriver, you can get in the ball-park pretty easy.

Ronny

iTrader: (1)

someone posted a week or so ago that demon sets up carb to run perfect out of box with no adjusting on owners part. that seems awfully easy to me! no wonder why tbi is sometimes converted to carb. my buddy that is professional mechanic does not understand why any one would run modified TBI with modified engine(me) over a straight carb. apparently he has no confidence that it(mine) will ever be right.

Grumpy

I ran mid 13's with a 355, using (what was) a Cross Fire, and that was about 8-9 years ago.

wade84

I doubt Demon can set up a carb anymore perfect than a mail order chip. I would bet a few adjustment on a demon carb could get more power.

JPrevost

Carbs are just like MAF, they directly meter the fuel based on actual air flow. Speed density is great when it's setup right but it's a royal PITA when it's not.
Carbs can and for the most part do run near perfect out of the box. This is because they're designed to give x amount of fuel with x amount of airflow through the venturi. Bigger motor gets the same AFR (or very close), the only thing that makes carbs harder to tune is the lack of data-aq. Other than that they're great for getting an engine up and running and for basic racing they're pretty dumby proof.

dimented24x7

iTrader: (2)

The reason why is that SD paired with a wetflow system is a pain to tune and alot of people put this, that, and the other on their cars with tbi and dont take the necesary steps to tune it. It runs horrible and they go off and spout that the tbi is absolute crap. SD is hard to tune. Its all emperical and based entirely on whats entered into the calibration for the motor. On top of that, the fueling is coupled very closely to the engine and even the timing your running. The ecm has no way, aside from the O2, to know what the engine needs. On top of this, the stock tables are crap. Theres very little timing and you can rest assured that the VE table will be off.

All the same things apply to the later model SD tpis, and on top of that you have all the resonance problems. There have been quite a few duds that had tpi on top of them as well. One that comes to mind is a guy that was running an old school flat tappet and he could barely break 200 HP with it because the cam and tpi intake where so mismatched. There was also a guy who switched over to a SD tpi and ran just as slow as he did with the tbi because it wasnt tuned.

You have an LS1 with MAF so you can take it for granted that the pcm will be able to fuel the motor even when its modded. There is a SD part (VE tables, etc.) to the system as well, but it doesnt seem to be as sensitive as the older straight SD systems. I can tell you first hand that a MAF takes alot of the difficulty out of tuning. Not only is there just a few variables controlling the fueling, namely the MAF, but the maf doesnt give a damn what kind of motor is parked behind it. It just reports the flow to the ecm and the ecm meters out the fueling. Simple as that. Of course, any sort of intake change will throw the calibration straight to hell, especially with a dual system like what the late model LS1s use. Some guys change their airboxes and get so frustrated that they contemplate going straight SD because they cant get the MAF to cooperate. Shows that there really is no perfect system Lets not even talk about what happens when they descreen them.

With SD it takes some knowledge to get the system to run well. People have showed that they can run very well. I was never really that good at it, so I whipped up my own system using the stock tbi and ecm along with an LS1 MAF. Gave my tbi the ease of use of a 650 carb, only I dont have all that stuff that normally comes along with a carb, like difficulty starting in cold weather. After a few tweaks, and some new parts to replace the tired stock stuff, it runs as good as my old L98. Not only that but unlike the pontiac it doesnt weight nearly two tons so its probably slightly faster.

If you wanted a reason, thats the best one in my honest opionion. The tbi ecm is arguably the hardest to tune of the lot. The tbi itself is fine and theres no reason it shouldnt be. After all, like a carb or the tpi it lets in air and squirts in fuel. The real problem is that you have to do the EFI tuning boogie to get the right ammount of fuel into the motor.

MrDude_1

thats probly the most accurate statement ive heard for TBI tuning....

TPI-454

Excellent explanation!

D-24×7, do you have a picture of this creation you can share?

dimented24x7

iTrader: (2)

Heres what it looks like now. You can sort of see the MAF in teh background.

dimented24x7

iTrader: (2)

Of course, now that Ive got it running good Im getting ready to tear it all back apart. Ive been harping alot about the MAF and I think that, for me at least, the system as a whole is a perfect blend of everything efi. The ultimate test will be if it just starts right up and runs well after a head swap. Im reserving my final opinion on it untill that moment.

I doubt the vortec heads alone will turn any record breaking times, but with the weenie stock type cam (204/214 .420/.442) it should make for a good 0-60 car that can beat most stuff off the line.

jbqualls

I have a 305 TBI in my otherwise stock car, 92 rs, and I can easily outrun a stock LS1 fbody. I dont have times or numbers yet, but I also own a stock 98 LS1 Camaro that cant come cloe to keeping up.

BronYrAur

iTrader: (1)

Yeah ok buddy

jbqualls

It's stroked, 335, World heads, 10.1 KB pistons, Very large cam, Bigger injectors, Bigger TBI, Fuel pump, custom prom, and the list goes on....the 92 is a 5 speed and the 98 is an automatic...

jbqualls

I built that engine with every possibly goodie just to prove everyone wrong that says dont go with the 305 or tbi, and I did a damn good job...

BronYrAur

iTrader: (1)

Well when you say an otherwise stock 305 TBI 92 RS that doesn't mean a 10:1 335 stroker. What are the specs on the cam, did you tune the PROM yourself? Got any timeslips?

jbqualls

I meant the car was stock...stock rear end, transmission and such...480 lift intake and exhaust...i forgot the other specs, i could looks them up,

jbqualls

the track hasnt opened yet here, so i'm not sure of any times, would love to know though, assuming I can get traction...

TPI-454

D-24×7, did you ever consider an air induction set-up to that of a Tuned Port Injected Camaro? Having the intake running straight towards the front, splitting, and fabbing up a ram-air effect from underneath the nose?

Off topic question.... what do you think about the Weiand Stealth intake (either EGR, or Non-EGR) for a TBI system, with the World 305 heads? Have you any experience with this particular manifold?

jbqualls

I'm actually looking at manifolds right now...I want the World Products Motown manifold, but 280 is a little rich for me right now. I'm gonna settle for a holley street dominator...although I've heard the single plenum works well with the tbi...

dimented24x7

iTrader: (2)

I havnt had any experience with the stealth directly, but from their specs it looks like a decent dual plane. I got the edelcrap because it was cheap, it fits, and Im not going to be using a large cam due to the TC, the way the trans is set up, and the 2.77 rear gears.

dimented24x7

iTrader: (2)

I thought about that, but running a 3.5" section of pipe and just a filter is alot easier and required less fabrication. Id like to set something like that up, though. Also, theres virtually zero clearance in front of the tbi so having the MAF face forward would be difficult. In addition to that, the fuel tends to splash around alot near the tbi so the farther the MAF is from the tbi, the better. If it where too close, the MAF would accumulate varnish, which would definatly not be good.

Ronny

iTrader: (1)

who provided the "bonnet" over the TB? i have a clearance issue. i need 1/4 inch clearance above the injector pod and i have about another 1/2 inch above the pod to the hood. i would like a cold air kit but could not find a combo that worked. i bought a TBI truck cold air kit but hood would not close. bonnet tto high. now i have a spacer on TB and a drop AC with a 14x 2 inch round AC. need to clear throttle arm on TB so the spacer needed. i think it is choking engine however my A/F is 13.5 on the WB? KN says flow insufficient for a 350 cid at 5700 rpms. only had a couple weeks to play with it. procharger has 3 diff height "bonnets" (2.00/2.75.3.75) but the $$$$ are too much. $180? that i could adapt to a vette SLP ram air system off ebay. thinking of a custom bonnet. it appears procharger uses a 3.75 inch dia inlet tube! maybe overkill? custom fab needed.

dimented24x7

iTrader: (2)

It was from, I think, superior airflow technologies. It was a closeout item so its no longer available now. They have aluminum ones like it but theyre expensive, and they have a partition in them which would be damn near impossible to cut out. With the resin/nylon one the two halves seperated so I was able to remove teh partition with a heated cutting tip.

Ronny

iTrader: (1)

thanks. i obtained the specific clearances from procharger. all i need to do is measure my existing setup and compare. it is more than a dome over TB. it directs the air up and over TB so that the path of air flow is verticle past the inj rather than sliding over edge of TB. odds are it wont fit anyway. i was lucky to find anything that will fit. tight squeeze.

91RedFirebird

Look what I have sitting around 1 caddy tbi air intake, send me a pm and you can have it for what ever shipping is.

TPI-454

Something like this;

Click Here

TPI-454

Yeah... the Stealth's have been around forever, but I too never had any experience with them. What's been grabbing my attention about them is their idle-7000 RPM power-band.

Now, you already installed you're Walbro right. I'd like to see you're set-up with the Stealth... along with some fabricated injector bosses (now running eight injectors) , and you're TB converted to a dry one by utilizing a block off plate.

The two biggest problems would be the fuel rail (in which I have a stock TPI one lying around, after my Stealth Ram install... which is your's if you consider this), and the injector bosses.
Couple the above with that CAI, and that would be some serious set-up! You sound like you're already well versed with PROM tuning, so that should be a breeze...

ezrs

Id love to keep my TBI setup, but it seems like it is very hard to get good tuning, when all is said and done. So I keep reading how tuning is very important, obviously it is, but how do you go about getting the tuning right? I really do not have a ton of confidence in mail-order and it seems like a major pain and hit or miss process to do it yourself.

I guess I ask myself why go through the trouble when I dont see very much in the line of sucess stories for the TBI setup but see tons for carb or pretty much any other option.

Ronny

iTrader: (1)

91 red firebird

Quote Look what I have sitting around 1 caddy tbi air intake, send me a pm and you can have it for what ever shipping is.

i sent you an email. did you receive it?

IROCaholic

The answer is you have to do it yourself. The only way to really get tbi dialed in is to do your own chips over and over again. Which is the reason I went carb and will never even consider modifying another tbi vehicle. Some guys on here are willing to do it and have had success, and thats good, but look at the other 90% of guys who are running 15+ second quarter mile times and it kind of gives you an idea of what your up against. It takes a special breed of man to do alot of modifications to tbi and stick with it.

Ronny

iTrader: (1)