Dennis91RS

yep TBI was cool and all but it had to go

check out what i did to the former LO3

90RS305

I'm suddenly starting to see a trend in "goodbye throttle body injection" threads....

scubas_90rs

I don't really want to get rid of it but sort of have to. There would be more work then I want to do at this time to convert from carb to tbi.

NEEDforSPEED

And i might be the next to go,
stuiped 160 buad ecms

r90camarors

I have nothing against swapping to a carb, as a lot of people seem to be more comfortable with it.

What I don't understand is why some people seem to think that it saves tuning and money, and the common idea that tbi cannot support power. The holley commander 950 tbi system supports 600hp and runs $1400 for everything-to include wb o2 input (sensor not included).
Buy the carb, hei dissy and coil, regulator, fuel pump, etc and it starts adding up. Maybe not $1400 worth, but for the extra money you gain a lot on many different levels with the fuel injection. More power throughout the powerband and throttle positions, better throttle response, gas milage, complete timing control, pin point a/f ratio, etc. Just my $.02

Also Dennis, isn't a 750 double pumper a little much for the 305? I'm not bashing, just asking. When I had my last combo, my engine builder recommended a 750 double pumper. That was on my 383 with protopline vortec heads, .510" lift hyd. roller cam and rpm air gap intake.

dimented24x7

iTrader: (2)

I thought the 750 was a bit much as well. But, I guess if its sitting on a dual plane without alot of plenum volume then its ok. On a single plane Im sure it would be a totally different story.

There are ways around that. Some easy, some more difficult. I chose the easy way out, namely put a 38,400 baud/1280 bps aldl rountine in place of the stock one. The harder, but much more rewarding way is lockers. Requires some soldering. If/when the speed reader comes out thatll take all the best mods and roll them into one package.

One reason why I stick with tbi is that the ecm is incredibly easy to use. Its just about the only one that you can easily have complete control over. The other ecms are more complicated.

The real complaint I have right now is fuel puddling. Its always been a problem and the car doesnt run as good at P/T as it could when the engine is still cold. Im sure if I had a carb it would still be a problem.

NEEDforSPEED

you maybe right there, but you cant data log s-h-i-t with a streming 160 buad rate
Tbi can make lots of power if given the time and work, IMO haveing tbi for years and years now, i come to realize that from a economical stand point its great, from a moding/power stand point its a little more difficult with the stock limitations, and thanks to the crapy heads, cam and intakes on the tbis people just assume tbi is bad, if there were decent heads, cam and intake there would be a lot better numbers out there and probably less bad mouthing of TBI and don't forget the chip work, but then the technology wasnt that great back in the time tbi was in the world,
And a lot of noobs think damn this cars slow then they swap it for tpi, witch the hole intake design in my mind sucks anything that wraps a full 90 degrees before it enters the cylinders doesn't seem right to me, im not a fan of carbs either but then again neither is my 500 cubic inch engine i have under the hood of my 74 caddy

BronYrAur

iTrader: (1)

Go over to the DIY-Prom board and do a search for the SpeedReader. It's a new product being developed that should be released soon that will datalog at a much much higher rate. Faster than the TPI P4 ECM's in fact. It is definitely something to look for.

Pablo

iTrader: (1)

Its no big deal,

I was die hard TBI, tried alot of things, started tuning with a WB and found that I just wasnt making power at high rpms for one reason or another despite having enough fuel.

Swapped back to carb and Im happy, I would be really happy with a 650 DP though.


Thats just the way it is. If i woulda just skipped messing with it my bird would probably be a low 12 second car by now with all the time and money I spent on FI.

r90camarors

The 160 buad rate is killer, it is painful enough to look at the data log. I can't even imagine tuning-as ashamed as I am to say it, I have never tuned a chip, just had it done for me with multiple log data(for a number of reasons not worth mentioning). The speed reader sounds great when using a stock ecm.

This time around, I am going with the Holley 900cfm tbi commander 950. I've done a lot of research on the pros and cons, and I think it will fit my needs. The price is right too. I just bought a '91 Z-28 as well from my buddy. It has a "custom" chip in it, but it was just a stab in the dark obviously. 383, Dart Pro 1 alum heads, zz4 hot cam, tpis intake and runners, 58mm tb, etc. Anyways long story short, I do plan on tuning that beast with the prominator, and pick up a little experiance before doing anything with the commander 950 on the rs.

I still have my holley 670 w/ 85pph injectors as well. I have toyed with the idea of putting that on the 383 going into the rs after the commander 950 swap, just to see how much power the 2bbl tbi can make and put the darn issue to rest. But that will depend on a few things.....an external regulator to get the fp to at least 30psi, making sure it doesn't go lean, and of course purposely removing the 4bbl tbi for a 2bbl tbi and getting over the fact that I will have taken a step backwards for that time period. Ah, who knows.

sunset92

when i switched to carb 2 years ago it was easy... i decided i didn't like the edlbrock 1405 and i then bought a holley 2" unit and i like it alot!! it pulls much harder off the line than the carb did! but like pablo said b4 it doesn't have much above 5 grand mine kinda sputters at 5000 rpms. but ihave not done alot of tuning yet.
after reading alot of info on the 1405 i couldn't get it completly in tune. it ran rich and i would lean it out almost all the way to no avail. so i switched back to tbi, i realy like the neck jerk at 2000 rpm's i just can't wait to get rid of the swirl port heads!

BMmonteSS

The 160 Baud rate isn't all that bad. You only need faster for tuning WOT and AE which you really need a WB for any way. My WB logs at 80 frames a second so that pretty much does it for me. Then for part throttle I love WINALDL because you just go for a long drive and end up with a nice BLM table to base your changes off of. I like to get avg's of my blm's instead of looking at random snipets of logs, so the 160 baud rate isn't an issue with this. Is TBI more complicated and time consuming than a carb? Hell yes it is, but you get so much more for your time and money invested, better milage (3 mpg highway and 5 city for me), and unbelievable control of fuel and spark compared to mechanical dissy's and carbs. If your just concerned with max power and only take the car out every now and then, there is no reason to dable in TBI or any injection for that matter. I drive my car 500 miles a week and race it every other weekend so I need the advantages FI has to offer.

Ohh yeah, and the speedreader will fix half of TBI's problems, and Rbob's ultimate TBI code will fix the other 45%. The last 5% is just the fact that it's a wet flow setup.

TPI-454

Very impressive indeed!

Token

I'm going to go carb next simply because I have no idea how to tune a prom, nor do I have the time/tools to learn.

del91_305

So how does it run now? Did you get a substantial gain? I myself am going to make the switch

BMmonteSS

I haven't gotten the car back to the track since I've gotten my WOT tuned correctly. I was running 8.9's in the 1/8th with an eldelbrock carb, and I ran about identical with my AFR all messed up. I actually ran slower MPH but had the same ET because of the increased torque down low. That was earlier this summer, I spent the rest of the summer auto-xing. I got my WB a couple of months ago and have improved my tune by leaps and bounds. I'd say I've found 15-20 hp over what I had earlier this summer. The most amazing thing is the throttle response, and low end torque. When I made the switch to FI it was because I found the limits of carbureation. Carbs just don't meter fuel very well at low engine speeds. They also CAN'T run the exact AFR you want under any condition. I also hate mechanical dissys. They are unreliable, inaccurate, and always gumming up. Not to mention that I absolutly love the fact that I can tune my car with a laptop. That in intself is the best part. With FI I'm the limiting factor, If something doesn't work it's because I'm the weak link. I think FI has made me a much better mechanic and has tought me more about engines than any other source.

Dennis91RS

it seems pretty happy with the 750 on it i went ahead and put smaller jets and squirters in it

im a big hick and alls i know is carb because i was raised on it i have nothing against TBI or any fuel injection in that matter i just dont have the knowledge to mess with it

ironroad9c1

no offence,but you would have to be a big hick to think a DP750 is gonna be worth a **** on a 305... you got a 3/4 cam too?..lol

NEEDforSPEED

well looks like tbis staying
thanks to the new iroc

TBI = cruising
TPI + LT1 intake + LT1 Heads = performance


no more f-ing around with the blue TBI camaro

ironroad9c1

yea that is something i thought about also is that guy that converts lt1 intakes to be used on reguler sbc's and swap my harness for a tpi one and the computer.

dimented24x7

iTrader: (2)

It might not be too much on a 305 if the plenum volume of the intake isnt real great. If your running a smaller dual plane the extra flow can help since the intake doesnt have much capacity to buffer out the peak demands from the cylinders intaking air.

To put it in perspective, the q-jet flows close to 800 cfm since they usually where run on small crappy stock intakes, although it has smaller primaries then the holley does to help improve P/T drivability. If I where to go to carb Id probably use a non-cc q-jet.

Token

go kill yourself. just because he's not into TBI doesnt mean you have to call him a big hick. no offense? yes, offense.

ironroad9c1

look here dumbass,i was informing him the 700cfm PLUS it being a double pumper is a very common mistake with guys wanting to hotrod **** ,its the old bigger is better thinking when its not ,yes a q jet was made in a 800cfm version ,but those where on 500 cid caddy engines , most 305's came with the 750 version ,but and i say BUT these carbs where progressive on the secondaries ,MEANING they only used what they needed ,hense the large flap on the back ,they didn''t have any secondary sqirters either and smaller primairies that gave you great milage at part throttle NOW before you go off shooting your mouth little boy ,back out of the **** sites for a little while and do some research before you start telling folks to go kill themselves .you might need a favor from me one day... now you can read this and come out a little smarter today and used it and found that at the best comditions he would only need 545 CFM so a 600 cfm edelbrock would be perfect and would be so crappy running on dyas that the baromiter drop more than half a point holleys suck for street use period.

"Engine size (CID) x Max RPM /3,456) x VE = CFM

For an example, a race 446 cubic inch engine turning 6,500 rpm with 103 percent VE (a street engine VE would typically be significantly less) provides the following result:

(446 x 6500/3456) x 1.03 = 863 cfm

In this scenario, it would seem as though an 850-cfm carb would be near ideal, and in the typical street/strip application the formula works out quite well. "

no it has nothing to do with me not likeing him becuase he isn't using the HOLY tbi ,thats not it ,i just hate to see folks **** **** up due to stupidity ,not sure about something ...use google its your friend ,i myself almost went to carb but instead i think i'm gonna move up the technoligy highway a bit and go lt1 swap ,so sit down shut up and learn something .

NEEDforSPEED

There are CFM maps to use, just search

like a turbo map,


CID at RPM = gets your CFM

oh and hey if anyone wants a 800cfm carb, i got one on my caddy, but you have to take the hole car, $450 obo!

dimented24x7

iTrader: (2)

I think this is getting a tad out of control, not to mention that its going off topic for the board that its on.