MightyMouse

I just got my 383 TBI running the other day and need some good advice on what kind of changes I will need to make to the chip. I only have about 5 miles on the motor so I dont know how it will run when I get into the throttle. It fires up and idles better than the stock motor did so that is a good sign. Just wanted to know what changes worked best.

ShiftyCapone

iTrader: (7)

Well you aer going to need larger injectors and a 2" TBI unit. Data logging will help you dial your car in right but to fully tune it for WOT you are going to need a wide band 02.

swerve-driver

Kudos on the choice. More detail on your build would help alot, but without knowing specifics, shifty's call on larger injectors and TBI unit with WB O2 sensor for tuning help are right on. Did you use the ZZ4 cam?
S-D

ssxmac

iTrader: (1)

about that WB O2.

Do you always need one for WOT tuning?

I was under the impression that our computer ran at a slower baud rate and that was the limiting factor on the amount of info we recieved from the o2 sensor. Do you need to get a faster computer too? (can you even do that?)

How much are WB O2's?

I havent gotten into tuning yet, but it will be very soon, just wondering what i should invest in.

-chuck

ShiftyCapone

iTrader: (7)

You need a wide band to effectively tune at WOT. Anything else is a stab in the dark. A wideband costs between 250 and 350 depending on which one you get. They make some that can be used with windal but I cannot remember the exact truth to that. I will be witnessing the use of one on a modded TBI soon with my buddy and we will post up the results.

MightyMouse

Yes.
Here is what the motor has in it

2"TBI with 305 injectors
1.5:1 aluminum roller rockers
Homemade TBI adapter
Performer EPS intake
ZZ4 cam
Ported vortec heads with S/S valves
12cc dish pistons with skirt coating =9.8:1
Gapless rings


I have all the stuff to do my own chips, except for the time.
I just wanted to know what some of the other guys with 383's did that was effective and things that they did that were not productive. Its just a time thing.

bbtaz97

iTrader: (3)

i hope to *** you mis-typed and are using atleast 350 injectors and not 350 injectors. your really starving that motor if your are. and need better injectors reallly soon.

Ronny

iTrader: (1)

what ever you do dont succumb to the WOT blast till you have the tune close to where it needs to be at idle and cruise. the first thing is to set the BPW in eprom. that takes into account the injector size and the CID and FP. that allows the ecm to understand the basics of what you have. you will need 90 lb injectors. i dont think you can run the 65's at high FP and get enough fuel. datallogging is required. even if you order"custom" chip you will still need to datalog. custom means close enough to get car to run. like 70-80 % there. TOT fueling will be close if you did your homework. on dyno i was 11.9/1. i was pleased with that. AE or pumpshot will be an issue. again more tuning. i believe you will need massive PS.

DM91RS

Shifty....do you remember the name of any of those? I can't remember and was wanting to look into one.

Thanks..... DM

ShiftyCapone

iTrader: (7)

Try a search in the DIY PROM board. It comes up an aweful lot and you should get some good info. I do not remember any off hand any particular brand names but group purchases are always comming up.

BronYrAur

iTrader: (1)

I think the Innovate WB was one of the names going around, I think there's a big thread over on the PRom board on the Innovate widebands.

Ronny

iTrader: (1)

i think i paid $350 or so for the innovate group purchase on this forum.

ssxmac

iTrader: (1)

Some one told me that the injectors on the 305 were the same as the ones on the 350. Maybe i misunderstood them and its just the throttle bodies that are the same.

Dang, WB 02 is expencieve....

ShiftyCapone

iTrader: (7)

The TBI units are the same but not the injectors.

Gunny Highway

iTrader: (1)

305 = 45#

standard 350 = 55#

Cop Car 350's = 65 - 68# depending on who you talk to

454 = 90#

Ronny

iTrader: (1)

give serious consideration to adding the 454 GM or holley 670 with 90lb injectors or the holley injectors that run high FP>

r90camarors

Like everybody else has said, you will need larger injectors. I run/ran 85pph at 22.5 psi, but they are the delphi units rated at 21psi. I think I may have been going static at around 6,400rpm, but I think that was because may tables stopped around there, plus it was the max spin the engine was able to handle anyways, so not a big deal. If you run gm injectors, I would imagine 90pph at 15 psi should be enough.

What you will really want to work on is your air flow after you fix the injector issue. Get rid of the rough bore openings, and do the rest of the ultimate mods. Most of what can be done to the gm unit can be done to the holley unit as well if you are using that as your base.

Also, if you have not done so, change your esc and knock sensor.

Other than that, the 383 swap is not all that different from a 350 swap. Possibly look into swapping intakes in the future. Mine changed to a totally different beast after I went from a performer intake to the rpm airgap. I think a single plane would work great as well

MightyMouse

Well I tried to burn a prom today for my new motor and I couldnt get any to work. I had a nice pile of proms that I bought and was saving for this project but they all had errors when programing. I did have one that was good but when I put it in the ecm I got the fast blinking SES. I may have the pocket programer set up wrong. New injectors are comming soon. I would like a single plane intake but I cant find a low rise one. The motor runs good tough, 1st gear will do nothing but spin if you put it to the floor, even @ 35mph, when it downshifts to 1st nothing but spin. I think there is alot more power locked in the prom but I need to find out what I am doing wrong so I can get back to tuneing.

steve8586iroc

MightyMouse, take a look at the Wieand lowrise singleplane intake HERE. It's only $107 at Summit. It just doesn't have egr provisions.

Steve

MightyMouse

That intake is what I would like but it wont fit vortec heads. Someone will come out with one that will fit vortec heads sooner or later tough. I need to buy the wife a new vehicle(Get uninsured moterist insurance) before I blow more money on the camaro anyway, computer tweaking takes a while so this should keep me busy. I put in 350 injectors the other day and that helped. I still cant burn chips on my laptop but I installed the stuff on another computer and it works now.

ben73

For comparison, my TBI 383 runs 90lb 454 injectors at 15psi..

Ronny

iTrader: (1)

GM performance parts I think has a vortec manifold ?

steve8586iroc

I know your not in the market for an intake any more, but the only single plane intake I know of is the Edelbrock Victor Jr and it is not a lowrise intake.

Steve

MightyMouse

The victor jr will not fit under my hood and is built for more RPM than I could use. Someone will have a low rise single plane on the market soon. The motor is running good and gets 22mpg on the hwy. I had to lower my BPW to improve the way the motor ran. Now I am fighting a low speed part throttle flat spot.

Ronny

iTrader: (1)

as you are prob aware CHP in latest issue used a GMPP vortec tbi manifold in their buildup. not sure if stock hood however. 92 camaro RS. i could swear someone found another vortec manifold for tbi on this forum a while back.

Ronny

iTrader: (1)

OBTW i ran 12.1/1 on dyno WOT so a WB was not absolutely necessary. but that may be dumb luck. after that run i dropped to 12.5/1 commanded in constants. previously set at 12/1 in constants..

ShiftyCapone

iTrader: (7)

Yea they used the stock hood. I don't think there is any other TBI specific intake manifold out there for the vortec heads. There are V6 intakes.

Ronny

iTrader: (1)

did not pay attention. how about a single plane/vortec with ol adapter plate?

ShiftyCapone

iTrader: (7)

Not sure about that. My buddy runs a dual plane RPM vortec intake on his 305 vortec TBI. Dewey has shed some new light on single plane use on our cars. You may want to send Chuck! and Dewey a PM.

Ronny

iTrader: (1)

i would expect with the popularity of vortec heads i would think someone offers a single plane. should not be that hard to retool a vic jr for vortec. is the position of the intake ports that much different? i am aware the bolts are way off.

steve8586iroc

Edelbrock has been making a victor jr intake for many years already. There is also a no name company that also makes a single plain too but as we've already descused this in this thread I will not go into detail.

Steve

BMmonteSS

so have your pistons splattered themselfs all over your heads yet? Just checking......Your running the equivalent of 50 somthing jets in a 750 holley carb........which means your stupid lean. GET SOME BIGGER INJECTORS. Depending on where your HP peak is you might get away with running 90 pph at 15-20 psi.

MightyMouse

No. They did have a nice layer of carbon and oily crap on them, the most I have ever seen.

I pulled the motor and rebuilt it. This time I am using AFR 195's, RPM air gap intake, demon 750 carb, Crane 222/230 cam and arround 10:1 compression. I have it ready to drop in but the engine lift that I always rent is broken so I am wating to find another lift. I also have a 2800 rpm stall converter that I will put in with the new engine.

swerve-driver

I'm lost.
Did you run the 383 and break it? Now you are re-building it?

How did it run prior to your current re-build? What happened?

And you're going carb?! Damn-it man! Where is your sense of adventure?

Mine is running great with TBI, but a trip to the track was disappointing. The 3.08 rear and the new T56 (2.66 1st) killed my launches. I feel like the engine runs strong though.

I bought a 12-bolt 3.90 for it and will be putting that in soon. I think that will help considerably.

Let us know how your new setup runs. Even though you are going to ahhh -cough- carb....

Seriously, it should run well.
Best
S-D

GOY

..............another 383 TBI is dead....

MightyMouse

The old 383 ran okay, but not good enough and it was buring oil. I was tired of looking under the hood and thinkng "what can I do now" so I pulled the engine and rebuilt it. I feel that TBI would limit the potential of my new combo so I went to carb.

BMmonteSS

You might want to say, "An untuned TBI setup would limit your motors potential"

DM91RS

That rear should work well with the 6spd.

Wished I had that setup

DM

MightyMouse

That is true but I think that TBI in general would have reduced the HP potential of my new combo.

The new motor runs great and pulls much harder in the upper rpms and quite a bit more down low. Now that I have a hole in my hood I have my eye on a 671. I have alot of traction problems that must be fixed before the 671 gets bolted on but I will report back when I have the blower.

TP355Z

"An untuned TBI setup would limit your motors potential"

I disagree. For different reasons. I say any 2 bbl TBI limits a motor.

I spent quite a while trying to get a mild 350 to run happily under an aftermarket Holley TBI and I think that regardless of the tune - no single-unit two-blade TBI can feed any performance motor sufficiently.

I picked up 20hp and 20ft/lbs by going to a 600cfm carb - and that was from a "670 cfm" holley tb - which actually isn't 670 cfm.

2 bbl flow ratings are run at double the flow pressure of a 4bbl carburetor / TBI - so a stock TBI flows closer to 450cfm (true) and the holley flows around 500cfm (true).

I'm curious as to whether anybody has done a direct comparison. I notice a lot of guys defend their system faithfully despite glaring insufficiencies. If its something you just wanna do, thats cool. But I get confused by a "performance TBI motor".


Kinda like "dehydrated water"!

Tyler

Go ahead, I know dehydrated water exists. But u get my point.

BronYrAur

iTrader: (1)

Did you tune the computer in your 350 before you put the 600cfm carb on? Are you sure you were getting sufficient fuel at WOT, i.e. did you run a wideband O2 sensor on it to see where your AFR was at? I couldn't see a mild 350 picking up that much power switching from TBI if it was tuned correctly.

Fast355

iTrader: (2)

The stock small block TBI does not pose any restriction up to around 300 FWHP.

The Holley 670 flows 670 CFM @ 1.5 in/hg NOT 3 in/hg as does the Big Block TBI.

TBI units are flowed at 1.5 in/hg.

Convert the numbers gathered in this thread from 28 in/H20 into 1.5 in/hg (used the airflow calculator in DD2000.)

https://www.thirdgen.org/techbb2/sho...h&pagenumber=2

574 CFM on the stock TBI=roughly 489 CFM @ 1.5 in/h20. Plenty of cars have gotten into the 12s on a 500 cfm two barrel.

I have pulled over 300 RWHP out of a 305 with a stock 454 TBI on top of it.

ALL EFI throttle bodies that I know of are flowed at 1.5 in/hg. Its funny that people have no problem at all getting 400+ FWHP out of a stock LT1 throttle body and it is smaller and flows less than the BBC TBI.

TBI is not fuel limited either. 61 lb/hr injectors at 28 PSI were ample to keep the A/F ratio at 11.9:1 while I ticked off a 301RWHP @ 5,500 pull with a 312 (.040 over 305) on a Mustang Dyno.

I pulled a perfectly good Demon off of my van and replaced it with a TBI system.

TP355Z

Interesting. I'm kinda curious then where I read that all 2bbls are run at higher pressure. Hm...

As far as the LT1 making the power it does - its simply a better motor. Choked is choked - but choked with good heads is a step in the right direction. lol

I guess having the desire to fiddle with TBI makes it worth it. But I still maintain that all things equal, a carb'ed motor will be happier than a TBI motor for most gearheads. Any of those 12 second-on-500cfm cars are probably supposed to be 10 second cars too.

I guess only 2 questions remain...
1. Why was a demon on a van motor??
2. What were the reasons for removing it? And economy doesn't count. lol

TRP

Fast355

iTrader: (2)

The van motor is more than you think.

Emissions, Driveability, Fuel mileage, Throttle Response, Tuneability, Cold starting.

Nah, the TBI engine is better.



It pulled 240 RWHP in the form you see there, stock 187 heads, ultimate TBI moded TBI, Edelbrock 3704 intake, stock van air cleaner, stock cast iron exhaust manifolds, single 3" cat.






9.89 @ 69.08 in the 1/8 with a 305 TBI in a 5,300 lbs van.

TP355Z

"Emissions, Driveability, Fuel mileage, Throttle Response, Tuneability, Cold starting."

Different worlds here. I'm thinking "summer car - must be tuned in garage" - you're thinking "reliable vehicle - must behave well."

To that end I'll agree. TBI is a ridiculously effective system for something so simple. High mileage TBI motors are real common too (I've seen 250,000 mile and 300,000 mile truck motors w/cross hatch still )

Falalala - back to the world of cavemen and sticks...


TRP


Until my LT1 emerges...

Fast355

iTrader: (2)

But I have the same or better power, better part-throttle acceleration, and a smoother powerband. Peak numbers may not have changed much, but the area under the curve is much better with TBI. Run a stock LG4 against a stock L03 and see what I mean. Just swapping to TBI, then tuning it, and running it against my previous baseline, the TBI put me to the end of the track quicker. Same HP but quicker times at more MPH.

BMmonteSS

I guess by your lack of response that you didn’t try to tune the TBI setup. How can you honestly say that you don’t think tuning would have helped? Take it from the guys who have tuned these TBI setups, it makes THE difference between a spitting sputtering 50 hp mess and a screaming 400hp snappy motor. Headers can throw off your tune enough that you won’t see much of a power increase on most stock tunes. Speed density systems are NOT like a mass air system where if there happens to be more air, then more fuel is added. With SD if there is more air the ECM is blind to it. It keeps feeding the same amount of fuel that it did with half power. This is exactly why you saw a power increase going to a carb. Carburetion is a form of mass air system, if you pull more air through the engine it pulls more fuel along with it, very simple.

As for air flow, you need to check your facts. TBI does flow near 700 cfm, and by my testing and others you don’t start seeing more than 1.5” of vacuum in the intake until you approach 400 HP. Even then, you’re only going to be giving up 5 maybe 10 hp to a bigger TB, which do exist. TBI is fuel limited to around 400HP, there just aren’t big enough injectors on the market.

If you’re making less than 400 hp, TBI will feed it fine with the proper tuning. Just being able to tune the system makes it better than a carb any day of the week. I have so much part throttle torque it’s unbelievable. With any form of FI (tbi included) you have so much more control of your AFR and timing it’s unbelievable. Actually timing is where the real advantage is, you can do some crazy stuff with FI that you could only dream about with a mechanical setup. I will admit at WOT and only WOT there is no advantage to TBI or any form of FI over a carb, as long as the engine is getting the proper amount of fuel and the mix is getting lit off at the right time it’s going to make max power. FI is just better everywhere else period, but you probably can’t see that from your cave.

TP355Z

At this point I'm going to excuse myself from this thread since I've apparently offended BMonteSS . Fast355 - I'm glad TBI works out for ya and that you're happy with it.

Best Regards.

TRP

BMmonteSS

Well yeah, you did. You basically came in here and said we’re all stupid for thinking a dinky little 2-barrel would work on a performance motor. You then sited your own feeble attempt at doing it with no chip tuning, without ever really doing any research on the subject.

There is a reason why there are so many of us using the system, if you would have simply asked or searched instead of stating your misguided beliefs we could of informed you of the misconceptions of the system, and the real limits and hurtles that you would face with the system.

I’m sorry I came across so sharp, but if I had a nickel for every “dude TBI sucks go TPI or carb” I’d be pretty rich. The crappy engines that TBI systems were attached to gave TBI a bad name, fuel is fuel and air is air, as long as you mix the two in correct quantities you’ll make power, and there is nothing inherently wrong with TBI.

TP355Z

Who said I didn't tune the motor?
Answer: You

Who said I thought you were all stupid?
Answer: You

Who said I didn't do any research?
Answer: You

Who said the system was limited but with its strong points?
Answer: Me

Who agreed with said statement?
Answer: Fast355

No word-in-mouthing please. My point is that for a real power application a carb is both easier to tune and get decent results with. I'd never say go to TPI either because the only TPI systems that are worth any money are $1500 mini-ram setups. Although I'm sure theres someone on the TPI forums that would like to take exception to that statement and get offended. Everyone needs to face the fact that NO stock system save the LTX LSX motors are worth anything without serious modifications.
Besides that - TPI is a better overall system than TBI because it has more thorough sensing / tuning capabilities just by design (8 injectors, MAF, etc) - aside from the runner length, etc etc.

TRP