Is there a kit you can get, that will work with the TBI and if so which one?

 

The holley 144 for the TBI truck is as close to a kit as there is. You could make some of them work, with some work, but the biggest flaw is the wet flow injectors, a limit of only two injectos, and a computer that doesn't sense boost. Getting a subercharger to physicly fit is the easiest of your issues.

 

i saw a guy in chevy high performance who had tbi with a paxton sn2000 maybe that might work?

 

Seriously anything past 400 hp and your going to be having fueling problems. Not many guys have even pushed that level. There is one guy who got TBI to work with a 747 ecm and it can sense boost, but for a beginner that would be an impossible project.

 

2 bbl tbi has this limit. but not 4bbl tbi. Holley makes 4 injector tbi units that are good for well over 750cfm. Staying with 2bbl tbi for high hp applications is like trying to stay with 2bbl carb, it doesn't make sense. You can use tbi to make crazy high amounts of hp.

 

Believe it or not I don't think air flow is THE problem with TBI. It's fuel. Think about it, a 454 TB has 50.1mm bores, there are lots of guys making big HP numbers with 48 mm tb on TPI and other injection setups. I do know fueling is a problem. The biggest HP number I have seen was on a x-fire vett that made 390 hp with two 90 lb/hr injectors at 15 psi, and he just recently found out his duty cycles were way too high, so with FP in the mid 20's he should be able to pull another 30 to 40 hp out of it being very optimistic. The problem with TBI is that with the way the ecm fires the injectors you only have 5ms to inject all the fuel you need at 6000 rpm. The amount of time you have to inject fuel is dendent on the rpm your running at, so if you can make all your HP down low then you have a better chance of feeding it. I think this is why the x-fire guys are able to pull some decent times out of their TBI systems, there long runner intakes are tailored to low rpm power.

Yes a holley 4-barrel unit will fix alot of these problems, but they cost mega bucks (close to stealth ram) and results have been marginal with oem ecm's. So an aftermarket ecm is almost required unless your really determined. Most people stick with TBI because it's cheap and it's what they have. If your willing and need to spend some money to make some big HP there is no reason to stay with TBI. Too many advantages to a MPI setup.

 

MPFI is definitely more advanced, though TPI is right alongside TBI as the lowest forms of fuel injection systems. "Upgrading" to tpi isn't as easy as tpi people would like to think, since it's not so much an upgrade as changing over to a parallel system that has it's own equal amount of pros and cons. This makes other, less logical, factors much more pursuasive. Not to say that the guy is on the wrong route with wanting to supercharge his tbi, maybe he is, but regardless of why he wants to supercharge the tbi system, the thread is about if it's been done and who sells the systems.

a 4bbl tbi unit would be more than capable of feeding supercharged applications, obviously you'd need to hack your computer to handle such things. Sometimes it's nice to have something few, if any, people have. Basically when supercharging a tbi setup, you get a supercharger for carb applications, since the intake manifold setup is the same. Of course, a supercharger kit for a carb setup wont include any sort of computer tuning, you'll have to do that yourself or get lucky and find a company that handles TBI too. Procharger has kits for carb and aftermarket EFI (likely pointing to TBI) . I'm getting their catalog in the mail very soon on that (plus tpi setups).

 

not sure if you saw it or not but a few days ago history channel had an episode of full throttle with 2 iroc-z that got supercharged. They used a vortech setup and just bolted it right up. The cars were originally tpi and the only other parts added were msd ignition, and a b&m aluminum radiator. I believe they made close to 360hp after catback exhaust was added.

VOR-4GF218-060S is the part number for it on summit. expect around $3500 for the whole setup.

 

I never suggested switching to TPI I just mentioined that the TB size has made lots of power on other forms of injection. If I were going to switch to MPFI, TPI would be out of the question. I'd like to think I'm helping him decide wether or not he wants to supercharge his TBI by giving him all the facts, letting him know exactly why TBI isn't the best solution that way he can plan around it's shortcomings. The fact is no one is making over 400 hp and very few have actually supercharged their TBI engines so every bit of info he can gather is going to help.

 

just pulled out my procharger dream catalog. they do list SC ers for TBI application. which i assume are late model TBI trucks. they state TBI works at low boost(12 lbs or less). they go on to state MPFI/speed density are a better choice. does the late model truck ECU(1990's) offer suitability for SCing? my 7747 i believe came out of a late model truck. is the map sensor the issue? is it that map/ECU too slow in response? would an open loop application be best? they also suggest swapping out to a WB linear sensor. my WB can be used in place of my narrow band again i believe in open loop fueling only. need to read up in manual. seems they are refering to open loop operation as A/F ratios will be rich with SCing...

 

Your best bet would be swapping to a 7749 computer. The problem with supercharging and a computer like the 7747 is that it can't sense the boost. Your VE tables only go up to 100 KPA manifold pressure and boost would put your volumetric efficiency beyond 100 kpa. I think the best setup for a low boost TBI motor would be a 749 and you need a 2 bar map sensor.

Check out the DIYPROM board there's a guy over there that guy TBI running on a '749. Might give you an idea of what has to be done.

 

To add to what he said, the 747 is plent fast, just can't use the 2 bar map sensor, as of right now you can't just plug a WB into a GM ecm and have everything work correctly. WB's are just for tuning. Open loop is just used to tune without the ecm trying to compensate your fueling based on the NB O2 sensor. Even with the 749, which can run TBI and the 2 bar map sensor, your still going to be out of fuel in the 400 hp range, maybe sooner since SC like richer AFR's.

 

in my innovative manual it states that the WB02 can be used in place of the stock NB 02 sensor. honestly i did not read it throughly. i would think still uses CL. do you think my car would benefit using the WB sensor in place of my NB? is my WB of serious higher quality or is it just designed differently(14.7/NB) than the NB is? I am not running emmishions so could command any A/F ratio i wish to.

 

They mean physically put your WB where your NB used to be. The zietronix unit does have a NB output so you can just wire it to where your NB used to be. Whether or not this works is still undecided. Some guys say it works fine, others say it doesn't work like the sock NB did.

The difference between NB and WB are basic. The NB is just that it can only sense 14.7 to 1 It is very acurate at this afr. It runs on a 0 to 1 volt scale. It switches over .450 volts when it senses 14.7. The WB can tell you your exact AFR from 10-1 to 21-1. Your WB runs on a 0-5 volt scale. It's as acurate as you need it to be. I'm not exactly sure but the NB out put on the zietronix unit doesn't switch back and forth like a stock sensor does. Our ecm's uses extensive coding to deciver how fast and how long the stock sensor switches, if the simulated NB doesn't do this exactly right it messes with the ecm. Your best bet is to put your ecm into open loop and tune your WOT and AE stuff with the WB, and use the NB for part throttle tuning. You can also just run open loop all the time and tune your entire fueling using the WB so you can decide what AFR you want to run. There isn't any way to just name an AFR and have the ecm automatically compensate....at least not in the near future. There are some guys working on some software that would use the WB to automatically tune the ecm with very little human interaction.

 

computer farted