Topic: switch the heads to run the multiport

[siniste367]

So Im not sure how old these posts are but i'm going to post anyway. My question is kind of diffrent. Im running a 86 comanche with the 2.5 from a 94 wrangler. Would I need to switch the heads to run the multiport of the 94? And the whole harness to? Or could i get way with just turboing the TBI? Im pretty sure you cant turbo the TBI but it seems easyer than changing the whole wirring harness and computer. Also since i dont have the harness or computer.

[sharpxmen]

So Im not sure how old these posts are but i'm going to post anyway. My question is kind of diffrent. Im running a 86 comanche with the 2.5 from a 94 wrangler. Would I need to switch the heads to run the multiport of the 94? And the whole harness to? Or could i get way with just turboing the TBI? Im pretty sure you cant turbo the TBI but it seems easyer than changing the whole wirring harness and computer. Also since i dont have the harness or computer.

i have no idea if you can turbo the TBI but to be honest if you can seal the t/b i don't see why not other than the limitation on the fuel delivery (you usually go to larger injectors for that so that can be a hurdle) but you can always run an extra injector for the additional fuel when you go in boost, there are some solutions out there for that.

I don't understand your question about the heads - you said you already have the 2.5 from a 94 wrangler, did you use the 89 cyl head?

[siniste367]

Hey thie is kind of an off question but I have a 86 comcanche with a 2.5 from a 94 wrangler. The head is still the one from the 86 so its still TBI. Could I still turbo this in the same way? I dont realy see why I couldnt but a second opinion would be great lol

[chardrc]

you can use the old head with the tbi or mpfi. for tbi you need the manifold and the tbi thermostat housing (for mpfi the other way around). if you can trick the computer to liking the turbo it could work (you'll just be the first person i know of turbocharging a tbi 2.5l jeep)... you can use bigger injectors from tbi Chevy's to get more flow and / or increase fuel pressure.

[siniste367]

Ok I think im going to try it. I thought about switching to a whole OBD2 setup but im a college kid with a limited budget so for now I think im gona see how this goes.

[sharpxmen]

you can use the old head with the tbi or mpfi. for tbi you need the manifold and the tbi thermostat housing (for mpfi the other way around). if you can trick the computer to liking the turbo it could work (you'll just be the first person i know of turbocharging a tbi 2.5l jeep)... you can use bigger injectors from tbi Chevy's to get more flow and / or increase fuel pressure.

does the TBI fuel pressure regulator have an internal vacuum reference? if it does it's fine, if it doesn't than that would be a major problem.

[chardrc]

does the TBI fuel pressure regulator have an internal vacuum reference? if it does it's fine, if it doesn't than that would be a major problem.

iirc it does have a internal pressure reference as it has a port under the throttle plate that goes into the fpr's chamber which is sealed to the outside world.

[chardrc]

iirc it does have a internal pressure reference as it has a port under the throttle plate that goes into the fpr's chamber which is sealed to the outside world.

going to have to take that back.. the wording in the fsm isn't totally clear to me on how they actually did this and why they did it this way but this is what it says on the subject of fpr and spring pressure.

'A small passage through the throttle body, regulator diaphragm, and the regulator casing vents the spring chamber to the atmospheric pressure. because the injector nozzle and spring chamber are vented to the same pressure, the volume of fuel injected is dependent only on the length of time the injector is energized (injector pulse width)"

[sharpxmen]

going to have to take that back.. the wording in the fsm isn't totally clear to me on how they actually did this and why they did it this way but this is what it says on the subject of fpr and spring pressure.

'A small passage through the throttle body, regulator diaphragm, and the regulator casing vents the spring chamber to the atmospheric pressure. because the injector nozzle and spring chamber are vented to the same pressure, the volume of fuel injected is dependent only on the length of time the injector is energized (injector pulse width)"

if the passage is inside the throttle body (even if it's not under the butterfly) then it might work, if it is outside the throttle body then the problem is that the relative pressure of the fuel (which is 15psi without boost) would be 15-<boost>, so if you run 6 psi of boost you end up at 9 psi differential which will affect the flow significantly.

I assume it could be modified if the passage doesn't go inside the t/b with some sort of a fitting if it's accessible that would be connected to the piping coming from the turbo so there is pressure reference on the diaphragm.

[cz777]

i have no idea if you can turbo the TBI but to be honest if you can seal the t/b i don't see why not other than the limitation on the fuel delivery (you usually go to larger injectors for that so that can be a hurdle) but you can always run an extra injector for the additional fuel when you go in boost, there are some solutions out there for that.

I don't understand your question about the heads - you said you already have the 2.5 from a 94 wrangler, did you use the 89 cyl head?

WOW!!! TBI with turbo = not a good mix but troubles!MPI with turbo = great move but talk about reengineering - stand along brain[programmable]  with wiring harness plus sensors like duel map -pressure/ vacuum plus rising rate fuel regulator!$$$$

[sharpxmen]

WOW!!! TBI with turbo = not a good mix but troubles!MPI with turbo = great move but talk about reengineering - stand along brain[programmable]  with wiring harness plus sensors like duel map -pressure/ vacuum plus rising rate fuel regulator!$$$$

1. why you quote my response?

2. what's "duel map -pressure/vacuum"?

3. old thread

[cz777]

1. why you quote my response? <-see that somebody was looking help

2. what's "duel map -pressure/vacuum"?<- duel acting MAP sensor

3. old thread <-it popped up by somebody was asking on it

[sharpxmen]

1. why you quote my response? <-see that somebody was looking help

ok, but I didn't ask the question so i guess i didn't understand why you were responding to my post, no big deal but just confusing.

2. what's "duel map -pressure/vacuum"?<- duel acting MAP sensor

i see what you mean, but there is no dual acting map sensor - you probably referring to a 2 bar or 3 bar MAP sensor as opposed to a 1 bar for normally aspirated engines.