I'm wondering if anyone has every installed a TBI from a 2.8 or larger motor to a 2.5, I think the modifying the intake would be straight forward, but what I wondering obout would be the ECM wirring hookups.

It would be quite the effort to adapt it over. The 2.8 is a multipoint fuel injection system with a seperate throttle body. The 'duke is a throttle body injection system.
There is a performance intake/throttle body combo for the 'duke, but it's rather uncommon these days.

Of course all this begs the question of Why? I don't think you'd see much of an improvement in power, especially with the head, exhaust, etc left stock.

What year 2.5? In 87 and 88 the newer style IAC and TPS were used. This was near the end of GM TBI stuff, so most TBI parts you find are going to the be the early 84-86 style. You'll have to change the connectors for the early style ones if you get an older throttle body and have the 87-88 2.5. Otherwise as long as you can bolt it to the intake and hook up the vacuum lines and fuel rails you should be good to go. Use the injector from the old 2.5 TB. You won't be flowing enough air to need a larger injector unless you have a lot of other mods.
To be honest, I don't think its worth trying to do anything to a Duke besides making sure its running right. They're not performance motors and you can't push them hard without blowing them up!

Is was thinking more on the line of a TBI from a s-10 truck. My motor has the cast-iron SD head along with 350 chevy pistions. I also have the holley TBI but I haven't been all that happy with performace. Just wondering if a TBI from a 2.8 or 350 would be better than the holley? I also am using the factory ECM which could also be a drawback as the motor doesn't want to rev past 6200 RPM, does the factory ECM have a rev limiter in it? Has anyone tried the Holley Pro-jection on the 2.5? Unfortanally because of the rules I'm stuck woth the TBI setup.

I am also interested in this, for what sounds like the exact same reason (racing fiero in itb, where we can't switch from the TBI).

I have an 88 notch back, w/ i believe the 88 intake, but i have yet to take it apart. i hear the older TB's were 1.6" and the Holley was 2.0". What about the 88 TB's? I have seen it quoted to be larger, but how much???

Also, the 6200 rpm max does seem a bit restrictive. Can the duke do 6500 consistently w/out blowing (i have a beefed up oil pump)? If so, how does one go about it? I assume some type of ECM chip swap.

Thanks.

4.3 TBI fits. Now for a "little" word of advice from my time building a high output Duke. "GO CARB" dont slack off with TBI and get your self a nice little 32/36 dgv or a 38 series Weber. You will not be dissappointed with a weber other than the tricky tuning it will give you more HP and with the turn of a screw it can be made emission safe. Though I am not sure if you have emissions in your area but if you do then get the 32/36 if not then get a 38 with a jet kit.

Webers are all mighty!

Wish i could...but SCCA will only allow what came stock on the car. Actually, if i could make changes to the intake, i would dump stock and go w/ Individual throttle bodies and injectors, w/ an aftermarket ECU...back to reality: anyone got info that TBI question (what size is the stock 88 TBI?)?

Thanks

The '87-'88 used the Model 700 TBI. What exactly are you sizing? The bore size? I can measure the extra one I have.

EDIT: I measured 44mm throttle bore size.

[This message has been edited by Hudini (edited 07-19-2007).]

Thanks Hudini. So, 44mm is about 1.73". Bigger than the 84-86 1.6, but not much bigger and substantially smaller than the holley. Guess i'll have to keep looking for the Holley TBI.

Anyone know a source for it?

quote Originally posted by crytical point: 4.3 TBI fits.

No no no. The 4.3 used a dual injector set up. If anything, you want the Model 300 TBI from the Crossfire 305s from early 80s Vette's, F-Birds, and Camaros. This thread has the Crossfire and 4.3 TBI units pictured so you can see what I'm talking about. Find the TBI from a Crossfire and have that bore measured.

Edit: Forgot to say, the reason the 4.3 TBI won't fit is because it's a 2BBL and too wide for the stock Duke intake.

Edit2: Forgot the link to the other thread! damn I'm losing it... https://www.fiero.nl/forum/Forum2/HTML/081209.html

[This message has been edited by AquaHusky (edited 07-20-2007).]

Just for reference, this is the best TBI (still being made) i have found for the duke. Is 2.0", like the original one Holley did for he duke, has a standalone fully (home) programmable ECU, and comes w/ it's own full harness:

(scroll to the right and down after bringing up the link)

http://www.alljeep.com/osco...=83&products_id=1014

The only negatives are that it would require an adapter plate to hook up to the fiero intake manifold, the fiero intake manifold would need to machined out to the 2.0" (just like it would for the holley), and the fact that it runs off it's own ECU means that it wouldn't be integrated w/ any of the systems being run off the stock ECM.

Oh, and of course the big negative is the cost!!!

[This message has been edited by ScotMac (edited 07-21-2007).]

quote Originally posted by AquaHusky: No no no. The 4.3 used a dual injector set up. If anything, you want the Model 300 TBI from the Crossfire 305s from early 80s Vette's, F-Birds, and Camaros. This thread has the Crossfire and 4.3 TBI units pictured so you can see what I'm talking about. Find the TBI from a Crossfire and have that bore measured. Edit: Forgot to say, the reason the 4.3 TBI won't fit is because it's a 2BBL and too wide for the stock Duke intake. Edit2: Forgot the link to the other thread! damn I'm losing it... https://www.fiero.nl/forum/Forum2/HTML/081209.html

Check these out.
http://cgi.ebay.com/ebaymot...eZWD1VQQcmdZViewItem
Assuming that the crossfire TBI unit will work with the Fiero (I think the front one will), this might be worth considering.
The only downside is that you must buy both of them, not just one.

[This message has been edited by patch (edited 07-22-2007).]

racer 151 you are not getting the perfomance you should from the holley,,why I do not know?? this should be the best available option, you get this tuned to your ports and flow and you can smoke some of the quad fours,not all but some,your best option run a quad four car.. your hogging everthing out you need to set up for the holley build around it I have not messed with this stuff in years ,,some where in the galaxy is the greasy jedi wino who knows the secret? but where he is you must find,, I still can,t beleave you can stay on the same lap with a quad

[This message has been edited by uhlanstan (edited 11-16-2007).]

Uh I found this thread by accident but it brings up one of my old projects. I had plans of installing a dual injector TBI off of a 4.3L V-6 awhile back. I made up a plate that would bolt to a 4bbl intake to mount the TBI. I had to make TBI spacer plates to put under the TBI because of the throttle arms not being able to move. Those are the TBI plates I have on Ebay now. I planned on using the V-6 computer, wiring harness, all sensors and the TBI. Just never got finished like so many things. I will try and post picks of the plate I made later if anyone wants to see it.

quote Originally posted by 151 racer: Is was thinking more on the line of a TBI from a s-10 truck. My motor has the cast-iron SD head along with 350 chevy pistions. I also have the holley TBI but I haven't been all that happy with performace. Just wondering if a TBI from a 2.8 or 350 would be better than the holley? I also am using the factory ECM which could also be a drawback as the motor doesn't want to rev past 6200 RPM, does the factory ECM have a rev limiter in it? Has anyone tried the Holley Pro-jection on the 2.5? Unfortanally because of the rules I'm stuck woth the TBI setup.

You do have the Holley intake manifold, dont you? What set of cams are you running?

quote Originally posted by 151 racer: I also am using the factory ECM which could also be a drawback as the motor doesn't want to rev past 6200 RPM, does the factory ECM have a rev limiter in it?

There are no tables in the ECM past 6200 RPM, at all. Even without a rev limiter, there's no place to dial in more timing with RPM or tune for VE. Its quite interesting, if you get yourself a copy of Tunercat, and the definition file, you'll soon realize why using the stock ECM calibration is a waste of your time.

quote Originally posted by KurtAKX: There are no tables in the ECM past 6200 RPM, at all. Even without a rev limiter, there's no place to dial in more timing with RPM or tune for VE. Its quite interesting, if you get yourself a copy of Tunercat, and the definition file, you'll soon realize why using the stock ECM calibration is a waste of your time.

I'm sure a Megasquirt will be more than adequate to run it and get as good or better milage. Does MS have an ECM that runs both ignition and fuel?

quote Originally posted by KurtAKX: There are no tables in the ECM past 6200 RPM, at all. Even without a rev limiter, there's no place to dial in more timing with RPM or tune for VE. Its quite interesting, if you get yourself a copy of Tunercat, and the definition file, you'll soon realize why using the stock ECM calibration is a waste of your time.

So I'm going to guess that you can't add in the needed "space" to make the maps to go past 6200?

Here's those pics.

I have no experience with ECM programing. I was looking at the Tunercat Info, does anybody have experience with this? For it is something that I would like to get into, I'm would like to know if the upper RPM limits can be changed.

You need to accent the best qualities of your engine! it is not a hi r p m engine..I admire your dedication..I have zero experience racing a duke,, you need to get your power in the lower ranges to keep the expenses to a minumum.. are you running the same rocker rollers on each side? I,m sure you are better at porting than I will ever be ,but the head is where you will gain power..you are not going to out rpm the ohc engines..I hope this makes sense to you..I would use principals from small block chevy,only because there is so much information available..apply sbc info to your 151 duke.. you are going to have to use torque $$ gearing, you can not match a hi rpm OHC motor,you have to use the strengths you have,, your hope is to get the best pull out of the corner and keep the lead to the next corner..you probably would get best perfromance from 1.6 intake and 1.7 exhaust these are available for the sbc you could adapt to your engine or they may be available for duke. I am guessing but know from my M/C racing days any little bit of info may help

[This message has been edited by uhlanstan (edited 11-16-2007).]

quote Originally posted by uhlanstan: I would use principals from small block chevy,only because there is so much information available..apply sbc info to your 151 duke..

What's good for the goose is not always good for the gander... Conventional rules of SBC do not always apply. Our (relatively) much weaker intake ports than most SBCs is a good example.

quote Originally posted by uhlanstan: ..you probably would get best perfromance from 1.6 intake and 1.7 exhaust these are available for the sbc you could adapt to your engine or they may be available for duke.

Duke rockers are already 1.7s intake and exhaust, going to 1.6 on the intake side would only decrease the amount of open intake port the cylinder would see. A good head is really the answer to power out of a duke.

Suck, Squeeze, Bang, Blow...... These are all controlled by the cam. Just remember, since a cam is fixed, you must give up something to get something else...

------------------
carpe diem