Is there anybody out there that could tell me this? I have a 400cid sbc just sitting up. In my car I just have a TBI 305. What would the pros and cons of reprogramming the PROM, setting the TBI on the 400, and dropping it in the car be?

 

Your TBI system will competley choke that 400. Hell, the TBI system chokes the 305, let alone a 400. You could either convert to carb, or go TPI.

 

Maybe you should talk to Jon Prevost in the TBI section.

 

Pros:

.......


Cons: what 88 said - what a waste of a potentially magnificent motor

Don't do it. I have a friend who tried exactly that, it ran like hammered dog plop so he got a Holley 900 CFM 4-barrel one, it wasn't much better.

 

oh c'mon guys....get real.

NJSPEEDER is currently working on a 406 TBI motor that will run 10s on motor alone.

of course nonbody thinks its possible, because nobody has done it.

check out the TBI board and you will get actually some useful information.

-brian

 

You will have to A) reconfig your fuel/air delivery system
B) figure out how it will be controlled.

I swapped out my 305 to 350 and the ECM couldn't handle it. I called Hypertech and they said the ECM would not be able to read the chip.

You would have to change out to a controllable computer setup from ACCEL or HOLLEY. Then you have to worry about inspections so the programming has to be the best way to go.

 

Get real? I think you need to get real. I stated before on the TBI board about making claims of grandeur like they were fact. Dont even attempt it here because I will lock and/or transfer this post. Until the day someone actually DOES it I will not allow anyone to make such rediculous claims here. I've already seen his 'combo' and his choice of heads leaves so much to be desired its not even funny.

In reality, the stock TBI setup is going to be just like a stock TPI setup or a stock CCC setup, its gonna choke that poor 400 so bad the intake might just disappear into the heads. The stock programming will have to be severly modified to make it run anything like it should and even then you will be wasting lots of power. If you are really serious about making the car run right, look into a different induction setup of some sort.

 

Ummm, just so Madmax doesn't yell at me....let me clarify when I was talking about the ACCEL and HOLLEY units... they come w/ an injection system. Problem is... since they are programable they are not street legal so you need to hide that fact by making it look as original as you can for emissions purposes

 

Go TPI? yeah right I wouldn't put a TPI on a 400 ever. I know there's a few guys with stock TPI units on 400/406s on the TPI board but I wouldn't put a FI unit that's designed for a 305 or smaller. The TBI flows 520cfm in stock form so it chokes the 305? I'm not so sure about that. The CFM required for a L03 would be 305x5000/3456= 441CFM @ 100% VE so with an engine with say ported stock heads, headers, aftermarket intake could achieve 85% VE so you would need 385CFM. So I think the 520CFM flow would be enough for a 305.

 

all that i saw in the first post was a "400cid sbc".

if everyone else sees something else, then i must need a new monitor.

not every 400 small block is going to be an all out race motor like some of you like to think.

lets see..l will use the CFM equation that everyone uses...a 400 at 6000 rpm...hmm...a little under 700 CFM at 100% efficiency. hmm and you can get a throttle body from holley that will flow 670 CFM that will plug right into a regular TBI wiring harness. and that is a regular old 2 barrel throttle body. hmm go figure.

-brian

 

Phsycodelic, what exactly have you done to the 400sb? Is it stock or moded? If it's stock, then the 305tb with a set of 350 65lb injectors and some custom eprom work would be doable. The cheapest and easyest way to get it running would be to just run a carb setup. But if emissions test is a problem and you want to take a stealth approch then stay with tbi and gear everything for low to mid range torque. If you don't spin the engine to the sun then there is no need for big cfm numbers. Since the 400 is a tq moster already then keep it that way. Nothing better to kick someones but and never turn the engine past 4500 to 5000 rpm and still knock down some good mpg's. The only mod that might need to done is to put in a decent tq producing cam and a set of 1 5/8" shorty headers and a 3" catback.

Just my .02

Steve

 

Yeah Z28 boy that sounds like a nice plan. I tried it. Wanna buy a Holley 670cfm? It'll be up for sale in a week or so. It doesn't cooperate with the 305 ecm. You'll also need to change out your intake. As mentioned on another post this made my car run VERY rich.

 

just wondering what you mean by cooperating with the 305 ecm...you mean the stock chip or the ecm as a whole?

just wondering....i'm assuming you mean just the chip?

-brian

 

Well this has gone from a simple question to off the deep end.

A 400 has entirely different airflow requirements than a 305. The TBI base is too small for the 400, no question. The stock TBI itself is too small. The chip, well the timing is going to be totally wrong and the fuel is going to be off. Ive done a few stock type setups, and I have been playing with a somewhat radical 350, and tuning is no fun. Once you go past 220 duration its a whole new ball game. For all I know, that 400 could have a peanut cam stuffed in it, but even at that the airflow isnt going to help the situation. And getting a custom chip from someone else is going to be an expensive waste of time IMO. You'd be better off jumping into an empty pool head first and doing it for yourself, and chances are in the end you will have better results. What in the end will end up happening is you will have lackluster performance. I'd say its going to be minimally better than what you have now if you just throw it on there, assuming the 400 is basically stock. Chances are the fuel mileage will drop a couple miles per gallon. Better idea is to let the 400 sit, make a plan for it, collect parts and knowledge, and do it all at once later. Rebuild the 400. Put some decent parts on it. Throw at least some ported heads on there. Play with the 305 for now, burn some chips and see what you can do and how things work, then step onto bigger and better things.

TPI... well I wouldnt stick that on there as it is either, but its no worse than a TBI. TBI, TPI... both are going to do the same thing on a 400, they are going to choke it. Neither was designed for a 400, both were designed for a 305. Roughly speaking, 25% less motor. Roughly speaking, 25% less airflow requirements same buildup. Thats alot. Will both motors perform? Sure. Will both be faster than the 305 setup? Of course. And then you take into account the engine is totally mismatched and the mileage is in the toilet, and you wonder if its worth it.

NJ, well I read your combo when you put it up. If you get that to work well I'd be really surprised, even if your car is lightened up alot. I've never seen those heads really perform all that well. Ive also never seen any good reviews of those heads when compared to its competitors. Last set I saw looked like something designed about 25 years ago and never changed, not a good thing IMO. If cost was an issue... and I were you... I would have gone with the pro-action heads instead. That cam is too big, even for a 400. Its going to be hard to get it to run right with a computerized setup. I'd really think about stepping down one notch on the cam profile into the 230 range, I think it will perform just as well in the end and wont be such a PITA to deal with. The manifold... well I guess with your intentions I can understand the choice, but all of those low rise dual carb setups are show, not go. Everything you listed for the engine really sounds like a mismatch. Apparently you are using desktop dyno or similar, try some smaller cams. If youre only gaining a couple horsepower with the bigger cam, its not helping and you should stick to the smaller one.

What I mean by the chip, and severe, is taking someone who assumably has no experience with chip burning and throwing them into the fire. Getting an aftermarket chip in my experience is a waste of time, its not a whole lot better than stock and leaves much to be desired. They just cant seem to get it right with some info over the phone and maybe a couple data files. Takes changes and re-reading and more changes to get it correct, hard to do on a one or two shot basis. And he will need a chip, its a much bigger engine with different requirements and the chips out there are just not going to work well. Now if he is ready to jump into burning with both feet, and is willing to setup some sort of scan tool or buy one then maybe its not entirely such a bad idea. But, I really would wait and practice on the 305 first.

 

Whoa!! I didn't mean to cause an uproar. It was just a simple question. I figured it couldn't be done because the measly Carter 625 I've got running on it now isn't enough gas. I built it for a four wheel drive, so it's set up for strictly low end grunt. It's got a CompCams 4x4xtreme energy cam in it. Just a 276, but it's long duration for bottom end. I was just trying to straddle the fence between reliability and power. However, my wife(who's name I'm under right now) already said NO. So the 400 will stay in the truck and the 305 in the car. I'm sure some of you can relate to the wife thing. Normally, I'd rebel and whine until she let me do it, but it's her car. Thanks for all the helpful info.

 

Phsycodelic -that's the way it is- sometimes you get no answers and sometimes you get overload-- with that said I will now add to it

NJ wrote:
YRUSOSLO, did you change the fuel pressure?
Y-I have aN FPR on the HOLLEY unit-

did you use the gasket that comes with teh 670unit, it is formed to allow use with a stock intake.
Y-IT DIDN'T MAKE SINCE TO SQUEEZE THE AIR FROM THE 2" HOLLEY BUTTERFLIES TO THE SMALLER INTAKE BORE

as far as your ecm flipping out, i think you shoudl look into other areas, my car has heads, 670tb, intake, and a cam and it runs great on teh stock chip.
MY ECM AND PROM COULDN'T RUN THE 350 I DROPPED IN. I CALLED FASTCHIPS (THEY DO CUSTOM BURNING) I TOLD THEM I HAD A HOLLEY 670 AND THEY SAID THEY COULDN'T BURN A CHIP FOR IT BECAUSE THEY AREN'T RELIABLE. I TESTED THE 350 HYPERTECH CHIP IN MY 305 COMPUTER AND MY ENGINE WARNING JUST KEPT FLASHING

all you need to do is adjust fuel pressure and timing and it will run very well. BOY DO i WISH i have called the chip companies too, i will say they are less than helpful and leave it at that. SNIP also, if the ecm is not capabel of reading a chip for a 350, what are all teh truck and caprice guys doing? MY QUESTION EXACTLY!!it sounds to me mroe liek the hypertech peopel were blowign you off than offering solid advice. AND FASTCHIP

as far as i know i will be the first one to try to make this kind of pump gas power with N/A tbi. SORRY CHARLIE, I'M WORKING ON IT RIGHT NOW. I LIKED THE FACT THAT I COULD PROGRAM THE BLEEPIN THING MYSELF AND NOT HAVE TO BE BOTHERED W/ CHIP BURNING.

the parts at least are capable of producing well over 500hp and over 550ft/lbs, i don't see why this can't be achieved once the computer is tuned in properly.

CHECK W/ HOLLEY AGAIN I BELIEVE THE COMMANDER 950 ONLY HANDLES UP TO 400 HP IF YOU WANT MORE THAN THAT YOU'LL HAVE TO GO UP ONE MORE STEP. HOLLEY TOLD ME 350 -400 HP SO CHECK INTO THAT BEFORE GETTING THE 950 PROGRAM

 

NJSPEED wrote;

yrusoslo, i looked into the holley ecm thing already. i was told that their ratings are directly related to using it with their parts. teh commander950 is a stand alone unit,
I KNOW THAT'S WHY I BOUGHT IT.

so when matched with other components ti will make whatever power that stuff is capable of.
HERE'S WHERE I DISAGREE. IF THE 950 COULD HANDLE/GIVE YOU ALL THE HP YOU NEEDED, THEN WHY BOTHER HAVING MORE THAN JUST THE 950?? I CAN'T REMEMBER WHAT THE NEXT STEP UP IS BUT I DO KNOW IT EXISTS AND IT'S NOT THERE TO RUN THE STREET CAR TO A 5 SEC 1/4 MILE SPEED MACHINE. THE MOTOR COULD NOT BE MAXIMIZED W/ A 950 IF IT WAS CAPABLE OF GOING OVER 400 HP. WHERE IN THE HE!! IS THAT HOLLEY NUMBER??
one of the things that i liek about the holley set up is that they have a prefab wiring harness and a base line program to run a pair of 2 barrel tb's from a 4Di kit they used to sell(it used a pair of 400cfm tb's and 65lbs injectors).
YEAH, I JUST GOT THE QUAD TB THAT CAME W/ THE 950 UNIT. I THINK TUNING WOULD BE HARD W/ TWO UNITS AND THAT'S WHY THEY DON'T SELL IT ANYMORE JUST MY 2 SENSE!

hopefully both of our projects will turn out and we can arrange a battle of the big time tbi's
YEAH RIGHT. I DON'T WANT TO GO MORE THAN 12SEC SO IF YOU BREAK INTO 11'S JUST KNOW THAT YOU WIN
my set up is a whiel away though, i have to take care of teh whole car before i can put any real power in it.
YEAH LIKE SFC'S ROLL CAGE? 3.73'S POSI TRACTION BARS CERTAIN PARTS DELETED FOR BETTER TRACTION IF YOU DON'T YOUR GONNA LOSE YOUR HIND END ON THE TRACK ALSO MAKE SURE YOUR ENGINE IS BUILT TO HANDLE SOME GIGGLE GAS


i will prolly build the motor starting liek mid season and try to have it doen on the stand and run in around when the season ends and i take the car off the road for the winter.
GO FIGURE!! IT WOULD TAKE TWO TIMS TO COME UP WITH THIS IDEA