No monte, you're not going to play your usual game of saying things and using language that will get the moderators to lock the thread and give you the last word. I will post my reply.

CFI is not TBI. You didn't say you could make 400hp with a system with two single bore throttle bodies. You said you could make 400-450 hp with a TBI. Where is it? This board is THE TBI place; that's why so many people who don't have Third Gens come here (including you); there's a wealth of information on modding TBI here that they can't find anywhere else. You spoke of there being only "100 people in the world who can tune TBI?", well, 98 of them are on this board. If it was doable, it would have been done, and it would have been done by someone active on here, who would have crowed about it to the heavens.

Then YOU quit standing around and do it yourself, but, until you do, you have no business telling me I am wrong for saying it can't be done. You argue the point as though I am the one going against the grain, that it HAS been done. You're talking about theoretical possibilities, at best. If you're going to take that strong of a stand, then you'd better be ready to back it up, and with facts and example, not theories and formulae.

So, you're using a formula of questionable accuracy to extrapolate your rwhp from your 1/4 mile mph, then using another formula of questionable accuracy to extrapolate your crank hp from the rwhp you extrapolated from your mph? Come on!

First, you're starting off a little generous. Assuming a vehicle weight of 3500lbs (an '84 MCSS had a curb weight of 3434lbs, according to montecarloss.com), 98 mph yields 267 hp [hp = (mph / 213.83)3.3003 x weight (lbs)].

More importantly, that formula is GENEROUS. My car makes 170 rwhp. I know, I've dynod it. Numerous times. My car weighs 3675lbs with me in it and a full tank of gas. I know, I've weighed it. Plugging those numbers into that formula yields a horsepower figure of 189, 19 more than the real number.

Then there's the question of WHICH formula you are going to use. 98mph and 3500lbs yields only 257hp using hp = (mph / 234)3 x weight (lbs), and 271 using hp = (mph / 230)3 x weight (lbs). All are generally accepted formulas, yet there's an 18 hp spread.

And therein lies the problem. You sit behind your computer with calculator in hand, and assume the numbers you come up with are REAL! Not only that, but you'll fight to the death over them. Those formulas are designed as a STARTING point; an ESTIMATION. They're NOT the be-all; end-all.

Dude, you need to get out of the house! There are birds, and trees and real GIRLS out there! I know it's a little tougher when you're in a small town, but Upgrades in Huntington has a Dynojet. Get a couple of buddies together, GET OUT OF THE HOUSE, and make a convoy out of it; it's only a 2 - 2 1/2 hour drive. Call the shop and see if you can arrange a group rate, many do. Here's their website: Welcome to Upgradesllc.com!

More important, it's actually fun to be around REAL PEOPLE, not AIM avatars; to get outside and breathe fresh air. Quit calculating and start DOING, you might actually like it!

Man, what PLANET are you on? First, I DID provide an example; the Goodwrench Quest, you just didn't take any notice of it (as usual). You never do. You read enough to see the person posting hasn't backed down, then you go back on the attack.

Here, I'll even give you a link to the freakin article (BTW, this was done back in 1999!): The Goodwrench Quest, Part V

Here's another one; 355, vortecs and LT4 Hot Cam; 422hp
Hot, Hot, Hot, Part II

Here's another one; 390 hp with Vortecs on 87 octane gas:
Agent 87, Part I

Can I make it any easier for you? And have you not picked up a car magazine in the last five years. Taking a basic 350 short block, bolting on a set of Vortecs with a Comp Cams Xtreme Energy cam, a Performer RPM Air Gap and a Road Demon 650-750 and making between 400 and 450 hp has been done so many times it's gotten BORING!

And most 383s making 390? Are you nuts?

Here's a 383 with Vortecs, making 449hp and nearly 500lb/ft by part III (they eventually make nearly 500 hp, but it's after a head swap):
The Twister, Part I

Here's another. By the end, they make 463hp and 503 lb-ft:
GM HT383 Crate Small-Block – Engine Build – Hot Rod Magazine

But, I have actual experience there, too. I've spent a couple of days and evening's over the past few weeks helping a friend and his dad work on his repo 32 Ford roadster. Last summer, he finished the car and make 404hp with a ZZ4 short block, Scroggin-Dickey upgraded vortecs, Comp Cams 268hr cam, Performer RPM Air Gap intake and a 750 Holley.

This summer's project is a Mass-Flo EFI, which we finished last week. 426hp and 455 lb-ft, with a torque curve as flat as Kansas.

What I can't understand is how ANY GM performance enthusiast could be so unaware of the hottest trend in small block performance in the last 5-10 years.

Oh no, you are NOT goint to go there. I'll be damned if I'm going to be sneered at and trivialized by some "expert" whose major accomplishment is a rooty-tooty 14 second car that, if the info on your sig is correct, hasn't even had an engine in it for over six months. Let me tell you something, Junior, I built and raced my first 12 second street car over 20 years ago, when you almost NEVER saw a car that could actually do that, and it was a freakin' Gremlin! I paid for nearly two years of college racing that car against smug know-it-alls like you who could only sneer "Rambler" and were too stupid to figure out that the whole reason for building the car was that the AMC dogleg port head was the best flowing small block head available at the time for ANY brand, and horsepower is all about the heads (and I was able to pick up a wrecked AMC police car cheap with a 401 in it.

When I finally just couldn't get any more action with the Gremlin, I moved on to a small block Chevelle that ran 12.40s on horsepower and and 11.70s on the juice. I know what it's like to go through the traps at 120mph, hit the brakes and have the pedal go to the floor. I know what it's like to bet my life's savings on a race, and win, and to bet my life's savings on a race and have the driveshaft drop on the starting line. I've DONE things, not just talked about them.

You go on and on about your engineering prowess and your formulas, but you haven't DONE anything. I've been using many of those formulas myself for over 20 years. I laid EVERY combination I ever put together out on paper before I bought a single part. That's why I never had to swap a carb or cam, and usually only had to go up or down a jet size or two to get the car dialed in because I did the research, I did the math, I found the people who KNEW and learned from them so I could match my components BEFORE building.

You have a 350 with higher compression heads, an aftermarket (I assume) cam, a carb intake and the 454 throttle body you're always talking about (I assume); the combination that is, according to you,the nuts; good for 400-450 hp, and you've only made 316 (extrapolated) hp by your own admission? You can't blame the tune, you're the expert tuner, so what is it? Let me tell you something, 316 crank hp from a 350 with heads, a cam, an intake, exhaust, a throttle body and a tune is freaking pathetic.

Who the hell are you to sneer at other people. You said:

You do understand that Tom Miller is the guy who tuned CHP's Mission 305 Camaro to 257 RWHP, don't you? Let's see, He's tuned a proven, documented 257 RWHP out of an L03, you've gotten an "estimated" 275 RWHP out of a 350.

He makes a living tuning TBIs for power; your masterpiece is sitting out in the front yard on cement blocks.

He says you can't get 400 hp out of a TBI; you say you can.

See the disconnect?

More importantly, see your arrogance at making that statement in the first place?

All you do is go off half cocked, making outrageous statements you can't support and attacking people who either know what they're talking about, or know enough to know they DON'T know what they're talking about, but are smart enough to seek out people who do know instead of shooting their big mouths off.

All of the trash you've talked about TPI, and your VERY non-stock TBI can barely beat a stock L98; if at all. The buddy whose dad has the 32 with the Mass-Flo EFI? He has a TPI Camaro. Last summer we put headers and exhaust on it and K&N filters. Other than that, it's absolutely stock, and it runs 14.20s-14.30s all day long. No heads, no cam, no intake, no throttle body, no AFPR, no tune. I'm amazed you'd dare to shoot your mouth off when your are so slow with your "TPI-killer".

Now, I readily admit my car is even slower than yours, but I'm not the one saying everyone in the TBI aftermarket doesn't know what they're talking about and swearing TBI is better than TPI. Your car proves MY point, not yours.

Once again, it comes back to the same point it always has, and always will. You insist it's "no problem" to make 400-450hp with a TBI. Prove it. Produce one.

 

Sweet Jesus! Its like the energizer bunny.


Hail to the Frog King

 

400hp TBI? Yes.

Once you couldn't tell any one the world was not flat.

How many TPI systems got junked in the 80's and early 90 in favor for a carb because TPI could not make any power?

New Ideas new tech. You won't ever see a 10 second GM TBI car but 400hp can be done and done cheaper then TPI. I'm poor and it was cheaper to mod TBI then swap to MPI and if I did have TPI I would have sold the TPI intake on ebay to help pay for some new fuel rails, bungs, a single plain and a new TB. When it comes down to it both TBI and TPI are both deeply flawed.

 

FANTASTIC!

GREAT!

NOTHING makes me happier.

Now, just show me the proof.

 

No for god sake don't!

It will not go well.... see part 1 of this post

 

Dude, be nice. I lived on Halls Ferry at Lindbergh and went to Cross Keys and St. Thomas Aquinas

 

80pph run around 35 psi and kept under 6400rpm will feed 400hp.

As far as being cheaper you can go to any swapmeet in the country and pick up a good used carb intake for $60-80, TPI can only dream about that.

Where is your proof that I'm wrong?

 

I don't have to prove you wrong. You're the one asserting it can be done, so the onus is on you to prove YOUR point. You're saying 400hp is not only easy to do, but cheaper to do with TBI. That's pretty interesting, as a bone stock TPI induction setup made over 400hp in Super Rod's test, so, to do it cheaper, you would have to bolt an absolutely stock TBI intake and throttle body onto that longblock, and have it not only make 400hp, but give you change.

http://www.compcams.com/Community/Ar...?ID=1737510521

And your formula is nothing but theory. Here's another theory for you: if I take those 80pph injectors and jack the fuel pressure up a bit more, say, to 55,000 psi, it'll make 10,000 hp!

Ok then, there you have it! TBI can make 10,000hp! Now, prove me wrong.

 

Dude, I am nice I just think its funny that everyone is getting all bent out of shape about this. Good luck finding your proof.

I live about 2 miles from New Halls and Lindbergh, I didnt go to school there though.

 

Ummm yeah the only thing your link showed was how well a stock TPI will choke a good motor and yes a stock TBI intake and TB will choke that motor too.

Whats your point?

As far as being cheaper for the money to by new injectors to fuel 400hp on that TPI you could get a used 454 with injectors and a used carb intake.

55,000 psi and 10,000 hp. Smoke alot of crack lately? Can't you keep things from being childish?

 

I lived right across the street from The Shops at Cross Keys, on Carefree Ln.

 

The point is, you said you could make 400hp cheaper with TBI induction than with TPI. I supplied an example of an absolutely stock TPI induction system breaking 400hp. Do you really believe you could bolt a stock TBI intake and throttle body on that long block and make 400hp? That's what you'd have to do to back up your claim, as they clearly spent NO money modifying the TPI, so any money you spent on an intake or throttle body would invalidate your claim. You couldn' make 400hp with TBI on that long block, even if you had a carb intake and 454 TB.

There's no question it's cheaper to buy intakes and injectors for TBI, the point is, cheaper don't get you to 400hp, and if you think getting to 400hp with a TBI is as simple as bolting on a carb intake and 454 throttle body, raising the fuel pressure and burning a chip, you are out of your mind.

It's not being childish, it's an extrapolation of the same illogical logic you applied. Just because you've calculated the fuel required to make 400hp and have found the TBI's injectors are theoretically capable of delivering that fuel is a far cry from actually making 400hp with a TBI. And the "under 6400 rpm" part of your comment? That makes no sense at all. RPMs have nothing to do with the fuel calculations you did.

There are dozens of 350 and 383s on here with carb intakes and 454 (or Holley 670) throttle bodies. Many have aftermarket cams and heads and raised fule pressure as well. All of the "go fast" parts that regularly make 400hp in carbed applications. So, why no 400hp TBIs? You have a 350, where are YOUR dyno graphs?

If 400hp with TBI was as easy as you assert, why have none of them popped up in these threads? Search the board, where are they? While I disagreed strongly with BMMonte, at least he acknowledged the difficulty of achieving the goal. You make it sound like a walk in the park. You clearly have no idea what you're talking about.

 

ROTFFLMMFAO.....

Sorry, that was just a little too funny!!!

 

You can make 400hp with a 300 cmf 2bbl carb and stock intake if you put a big enough motor under it, that does not mean you should use it.

No its not that easy, at the same time I don't see any 400hp SD TPI cars running stock tuning or fuel pumps.

the 6400 makes lots of sence, TBI only has two injectors and one fires for each cylinder. Above that there is not enough time for proper fueling.

Show me some combo's that where properly tuned with the right tbi parts to make 400 hp and then show me where they made 400 hp after a swap to TPI or carb.

My point is that TBI can hit 400 hp and alittle more also that it can be done cheaper to its limits than TPI.

 

GREAT!

WONDERFUL!

Now, show me one.

 

Got one in in the driveway. Gave me fits for over a year to get it to the point where it drove nice and idle. Just scrapped the edlebrock headers and 3inch flowmaster set up for some hooker long tubes and as soon as I can aford it Rbob's EBL and a muflex 4inch and Y pipe. But I know you don't want to hear all that. As soon as it goes back together and get retuned I'll have it dynoed just for you.

 

These kind of posts are utterly ridiculous. You just lost all credibility in my eyes. Nobody is going to build a stout motor and choke it with stock induction, be it TPI or TBI, leave that to the worthless magazines that have money to burn.

Most people on this board bought a TBI car because they could only afford the low end of the Thirdgen lineup. Do you really think these same people are going to magically pull the money out of there **** to fund a 400hp motor? That's a ludicrous suggestion. BMmonte strikes me as a pretty cool dude, knows his stuff about TBI and can tune a TBI motor, what's your deal with calling him out so aggressively? You are a bit too relentless, making a new post to reply to one that was locked is almost a guaranteed probation, wouldn't you think? I've seen you make good posts before, and I don't think you're a bad guy, but ease up, take a deep breath and realize this isn't going to kill you if some guys think it can make 400hp and you disagree.

I personally believe it can support that HP, probably even more. Granted, I think that at that level of power you would be holding the motor back a bit with airflow limits, but it will make the power nevertheless. Many people have run these injectors up to around 40psi, that's a hell of a lot of fuel with a BBC injector set. So, why wouldn't you be able to push it that high?

The best example of big power I can think of off the top of my head is "ben73"'s combo, I think he's got a Vette, so probably quite a bit lighter, but I think he was trapping in the 115 MPH range. Don't quote me on that though, I don't feel like looking it up. I'm not going to get into it more.

 

I look forward to seeing it.

And, all kidding, teasing, sarcasm, facetiousness aside, I'll be the first to congratulate you if you get there.

 

I dont mind a debate, but lets keep it nice...

With TBI, whatever you can feasibly make with with a 650 CFM carb, you can make with the TBI. Functionally, theyre the same. The main difference is the way the fuel is handled. TBI is speed density, which really has no place on TBI. With TBI, the fueling dynamics make it nearly impossible to have any sort of real world model for what the fueling should be. If youve worked with TBI, you know that no matter what the temp is outside, the tbi is almost always sweating and cold. Due to this, you never know what the air temp in the intake is, or how dense it is, or what the mass of the air is. Its all emperical, which makes it difficult to tune. This is one of the reasons that it has such a bad rep, is that its hard to get it to work properly unless you know what your doing.

Set up properly, it works just as well, and a whole lot better, then a carb. I had a similar car with a 600 CFM holley on it, and I can say that the tbi is alot easier to tune, and extremly flexible. Even after mods, almost no tuning is needed with the proper system. Bolt it on, and go... Will you make 500+ HP? Doubt it... But, 350-400 HP is feasible. It certainly made enough power to go 0-60 in around 5.25 secs when the car was still running and made enough torque to badly shear the subframe rails and wrinkle the trans tunnel. Not too bad for a pile of old junk.

People say this, that, and the other about TBI, but really, theres nothing wrong with TBI itself. Its GMs take on how the system should be set up is whats wrong. It was utter get it out the door for cheap and make it run along time garbage. Its not expensive to get the system to work, but the only part you can use is really the TBI itself. Like all other stock parts, the rest of the stuff on the vehicle is junk, and should be left in the scrap heap where it belongs.

 

Why this obsession with a 400-HP, throttle body injected, 305 anyways? The boys over at Hot Rod magazine achieved 400-HP with a carb, along with sacrificing the engine's driveability for the street while they were at it. I personally don't feel "hitting" the 400-HP mark (rather, peak) w/TBI will be that much of an accomplishment. The TBI that averages 350-HP throughout the entire RPM band will still walk all over the TBI that "peaks" at four hundred, regardless...

 

ummm ... you're kidding, right dude?

This whole thing started in the original thread when you said:

I disagreed, BMmonte came in, as he always does anytime anyone says TBI may not be better than TPI, and we were off to the races.

This has never been about a 305 making 400hp, by the way, it's been about TBI. BMmonte insisted a 350 TBI could easily make "400-450hp". I only used 305s for comparative value simply because they were both available in F-bodies.

 

In all fairness, I was not kidding. I initially didn't respond to you, I responded to someone brand new regarding his TBI application. Yes, it is in my opinion that the LO3 will make just as much, if not more, than the LB9, as well as it being my opinion, that an LO5 will make just as much, if not more, that the L98 (note how I added, "in the long run", as I forsee good things coming with Rbob's EBL).

The last thing I would want, is to encourage a new member to wrestle with his gas tank in order to swap fuel pumps. It's not an easy job for a beginner, especially the harness. Being a member on here yourself for quite sometime, I would imagine you would have the decency to put such an arguement to rest for a moment, and try to encourage our new member, and try to make a positive impact. Wolken already underlined the fact that he was staying TBI, so let's leave it at that, and continue encouraging him.

It sounds like BMmonte is one of those rare TBI representative's who is trying to keep this ancient system in the running. There have been many TBI ambassador's on this site who abandoned ship, just be glad that there are a few, such as BMMonte, keeping the concept alive. Yes, on paper, the TBI should be producing the numbers. It's obviously not been proven yet, but it eventually will be. With the advent of EBL, it's only a matter of time.

 

Dude, if only that was so. Super Chevy made 485hp with a 650 Road Demon in Danger Mouse Part 28 (December, '04). Do you really think you could bolt a TBI on it, tune it properly, and get even close to that result?

Before I go any further, understand that I LIKE TBI. I've had mine for 3 1/2 years; it's reliable, it's smooth, it's torquey, and it gets great mileage, but, it is what it is. So many people on this board have such a "black or white" view; TBI is the be-all, end-all, and anyone who suggests it isn't is THE ENEMY. Understang and accepting something's limits doen't mean you like it any less. We have newbies coming onto this board every day, not knowing much about TBI and trying to learn more. I think those of us who know more have a responsibility to make sure the information disseminated on this board is accurate and realistic.

Now, back to the comparison to a 650 carb. To make that comparison, you have to get on the same playing field. Holley says the formula for converting airflow at 3"hg (TBI) to airflow at 1.5"hg (4 bbl carb) is cfm @ 3"hg x 70.7 = cfm @ 1.5"hg, so a 670 Holley's 1.5" airflow is in the neighborhood of 474cfm.

Since no one knows what the factory rating for a 454 TB is, let's assume 700cfm @ 3". That converts to 495 cfm. Also, be aware that, according to the engineer in charge of all fuel injection products at Holley, all TBI throttle bodies are flowed without the injector pd, so the real world airflow is even less.

It's the lack of airflow (and turbulence in the airstream caused by the injector pod) which, I believe, is the main obstacle in making power with TBI.

Again, that doesn't mean I think TBI sucks, but, I just don't think you're going to get to 400hp and beyond with it, and the complete absence of anyone's having done it is convincing proof of that to me. That's why my response to anyone who asserts that TBI CAN make that kind of power is, and always will be: "show me one".

Every single expert I've spoken with in the TBI power industry says it can't be done. When I argued with him about it, the guy at CFM Technologies said he gets at least a dozen calls a month from people who want to make that power, and would absolutely LOVE to be able to sell them the parts to do it. he said they had tried numerous times, an an actual engine dyno, under ideal conditions, and had just not been able to do it.

Now, here's this guy, who makes his living from making and selling TBI power parts, and who has actually tried to hit that power level on a dyno and missed; and here is everyone else in the TBI power industry saying it can't be done. On the other hand are people arguing it can be done and offering fueling equations and a CFI setup as their proof. Sorry, I gotta see it before I'll believe it.

Also, let me clarify the "it can't be done" statement. You could probably overbuild an engine to the point where it COULD make 400 hp. Look at the Super Rod article I posted, where the stock TPI made 410 hp. It hit that mark at 4400 rpm! Clearly you could bolt an RPM Air Gap and 850 Mighty Demon on that engine and get to 500+ hp. It just wouldn't make sense to put the kind of money into the parts in that long block, only to bolt a stock TPI on top of it. It'd be like remodeling your kitchen and putting granite countertops and Sub Zero stainless steel appliance, only to put linoleum tile on the floor. It just wouldn't make sense.

There are a number of 350s and 383s on here which, I believe, would be capable of 400+hp with a carb, but which don't even get close with TBI. To get to that 400hp mark with TBI, I believe you'd have to overbuild to an absolutely ridiculous point. I'll bet you could bolt a TBI onto Tony Stewart's Nascar motor, for example, and make 400hp. Probably at around 3500 rpm. Ha ha ha.

 

Just remember that I was encouraging him as well. The first thing I said was that i believed he'd be better off with the TBI, BUT, I wanted to make sure he understood the choice he was making.

Being an ambassador is fine, but be a realistic ambassador. Outline the positives AND the negatives of TBI to newbies, help them set REALISTIC goals for their cars, then let them decide what they want to do. And don't feel a need to jump in and attack ANYONE who DARES to suggest what you're ambassadoring (I know that's not a word, but I like it) is not the ABSOLUTE GREATEST; the ONLY way to go.

There's a difference between liking something and being psycho over something; it has something to do with one's grip on reality.

 

I wanted to touch on this subject. Anyone, who opens up a Summit Racing catalog, can plainly see for themselves the choices that a carbureted application has to chose from. There's like what, "three" intake manifolds, from three seperate vendor's, to chose from as a TBI upgrade (Vortec, Edelbrock & Holley)? How many throttle bodies does the average TBI enthusiast have to choose from, two (the Holley 670-cfm, and the used 454 model)? Forget about the wonderful injector selection...

Not too many people have delved into TBI perfomance, despite Mr. Miller's attempt. Those that have, based there setups on the huge selection readily available from the aftermarket (sarcasm). Ten years ago, who in their right mind would have thought to see a ten second Honda Civic prowling the street. The concept was completely ludicrous by our beloved US muscle magazine editors, it couldn't be done. However, it took the dedication of it's enthusiasts to indeed make it a reality!

This is what is happening before you're very eyes. Have fun, enjoy the ride...

 

I agree with you there, but, the reality is (and I know you don't want to hear this ), when you do the numbers, TBI is more than capeable of producing such horsepower figures. The part selection to attain such figures is severely limited though, as is evident by everyone in this forum nickel and diming their part selection....

 

You see, Click Here. If TBI enthusiasts had much more access to such aftermarket designs (the above is the only one, and its designed for truck applications), for a bolt on scenario, I believe the outcome would be completely different....

 

Now, back to the comparison to a 650 carb. To make that comparison, you have to get on the same playing field. Holley says the formula for converting airflow at 3"hg (TBI) to airflow at 1.5"hg (4 bbl carb) is cfm @ 3"hg x 70.7 = cfm @ 1.5"hg, so a 670 Holley's 1.5" airflow is in the neighborhood of 474cfm.

The 2" TBI is nearly the size of the q-jet secondaries, and has no jets, or anything else to block the flow. Ive measured an equivelent volume of at least 500 CFM, and I havnt seen that much of a pressure drop though the intake track. I think 600-650 CFM is a reasonable estimate for the flow. There also has been testing on the 2" monobarrels that backs this up.

 

You know what? I agree with you. I'd never really thought about it that much, but when I do, it makes total sense.

The Edelbrock RPM Air Gap intake, for example, revolutionized intake design. Nothing else even comes close. Vortec heads made 400hp not only commonplace, but cheap. There are no parts like that being developed for TBI, and, there probably won't be. Since GM isn't producing it anymore, it's pretty much a dead-end except for the die-hard enthusiast, very few of which have the abilities or resources necessary to come up with intake manifolds and throttle bodies.

Earlier, you mentioned rbob's Embedded Lockers. I agree, it looks amazing, but, I don't know whether it's going to raise the power threshold of TBI so much as it's going to make it easier for people to reach that threshold. I don't know, that's way beyond my level of expertise.

 

I agree 100%. Every induction system has its pros, cons and limitations. Many of TBI's limitations are actually limitations of the software being employed in conjunction with it, and its reliance on a MAP sensor. But I also believe that TBI has much potential because of certain other advantages. In the end, it simply comes down to: Can the induction system supply the engine with the proper mixture over the RPM range that the particular motor will be operating? I think in the VAST majority of street-driven cases TBI can do this ...certainly as well as TPI (I would argue better). But I can also see the limitations of TBI - at least in the form that GM produced it - for 400+ hp applications. That isn't to say that TBI is limited to 400 hp, simply that the further you get away from GM's original design specs the more you have to modify the system.

For instance, GM's 90 lb injectors can feed over 400 hp, but will the pulse-width be too "narrow" for the motor to idle? It depends on the size of the motor and its VE at idle. I once put 90 pounders on a stock L03. Of course, everyone told me that it wouldn't work (including the people that I bought the injectors from), but the math indicated otherwise, and, sure enough, it fired up and idled like a kitten (with merely a BPC adjustment in the PROM - I tweaked it a little afterwards). I had enough flow to support well over 300 hp and was idling fine on a stock L03. I have no doubt that that TBI setup on a hotter motor and an increase in fuel pressure could feed 400 hp. The balancing act would be to get a 400 hp motor which produces a stable enough idle vacuum to achieve a good idle with the TBI and keeping the pulse-width high enough at idle to operate properly. Theoretically, I really don't think this would be a problem with a properly prepared 350 or 383 ...or with a more "advanced" fueling algorithm in the PROM.

Could you use two TBI units on a dual carb manifold and use a second ECM to control the second TBI? Why not? ...But you'd be drifting pretty far from GM's original setup, and you'd need significant know-how and skill to tune it in. It doesn't mean that it's impossible, or maybe even that difficult, but it does require some thinking outside of the box and using your head.

All in all, I think this place would be a lot better off if people concentrated on solutions rather than problems ...sure we have to acknowledge limitations, but we also have to recognize which limitations are real and which are merely apparent.

 

^^ Dimented, you're playing right into his hands. He's quite aware of the formulae, he'll just keep requesting the dyno sheet to substantiate it on a TBI oriented system...

 

Here we go again.

1) 2" monobarrels are not GM TBI throttle bodies.

2) When the chief engineer in charge of ALL fuel injection for the company that MAKES the throttle body says 474 cfm, I'm going to buy it.

Now, if you want to prove him wrong, then PROVE him wrong. Take a 650 4bbl and a 670 throttle body, put them both on the same flow bench, and post the results.

That is the only way to make a reasonable, direct comparison between the two. Anything else is just conjecture; conjecture that is not only NOT backed up by any comparative testing, but which is also refuted by the fact that no one on this board is making the power 600-650cfm would allow, despite the fect that they have combinations that would if they were carbed rather than TBI. Corpus delecti sum.

 

Would the data and cite from someone that has measured the TBI CFM be OK?

Quoted from:

TBI AirFlow - Page 4 - FULLSIZEforums - Chevy Truck


I'm sure all you guys know that these cfm data need to be converted from 28"H2O to 1.5 inHg:

TB with injectors/injector pod, no air cleaner - 575 cfm @ 28"H2O = 490 cfm @ 1.5 inHg
TB with injector/injector pod plus injector pod spacer installed - 590 cfm @ 28"H2O = 502 cfm @ 1.5 inHg
TB w/o injectors/injector pod - 610 cfm @ 28"H2O = 520 cfm @ 1.5 inHg




Here's the correction factor for the 454 TB data:

TB with injectors/injector pod, no air cleaner - 755 cfm @ 28"H2O = 643.3 cfm @ 1.5 inHg
TB with injector/injector pod plus injector pod spacer installed - 765 cfm @ 28"H2O = 651.8 cfm @ 1.5 inHg
TB w/o injectors/injector pod - 790 cfm @ 28"H2O = 673.1 cfm @ 1.5 inHg

The 350 TB has 1 11/16" throttle blades and the 454 TB has 2" throttle blades. If you were to get a Hi-flow 350 unit with 1 13/16" throttle blades, flow should be about 590 cfm w/o the injector pod.
This is spot-on to the flow data given from Turbo City with their cfm ratings. I guess this solves the debate of whether the 2-barrel TB uses the 3"Hg or 1.5"Hg standard for airflow measurements.

Thanks airdeano.


RBob.

 

I can back that data with what Ive seen. At around 210 gms/sec of airflow, which is somewhere around 500 CFM conservativly, I get less then 1.5 inHg drop through the whole intake track (air cleaner, MAF, carb hat, TBI)

 

Don't know. That's a dead link, so I have no way of seeing how he arrived at those results.

If they're correct however, a stock small block throttle body flows 16 more cfm than Holley says their 670 flows. That's pretty interesting.

 

1) 2" monobarrels are not GM TBI throttle bodies.

GM made them. They use the same style pod, injectors and butterflies. It really is half of a TBI.

2) When the chief engineer in charge of ALL fuel injection for the company that MAKES the throttle body says 474 cfm for the stock unit, i assume, I'm going to buy it.

 

The flows at 28" H20 and 1.5 inHg should be valid provided that theyre not near the speed of sound, which they shouldnt be. Looks like the air velocity is around 200 MPH or so. Fast, but slow enough for the equations to be valid.

 

Link has been updated. . .

Here it is for ease of use:

TBI AirFlow - Page 4 - FULLSIZEforums - Chevy Truck

RBob.

 

A few words out of an entire argument was not the reason it was locked. I could care less who posted the "last word". The first thread was locked for a reason. Redundant arguments don't get us anywhere folks. There is plenty in these two thread for people to extract what they need out of them. Don't give me any of this "last word" crap. If you guys still want to debate this take it to PM.