Topic: Finally (seriously) considering turboing my 4-banger

[jfrabat]

OK, so I am now seriously considering this, and would like some opinions.

First of, if I run 6~8 lbs of boost, how will the AX-5 and the D35 hold up with 33's?

Also, will my current 19# injectors work with the turbo, or will I need new ones?  Keep in mind I have an adjustable FPR already in place, and it's set for 46 PSI IIRC (Sharp, it was 46, right?  The Jeep is in Panama and I am in Costa Rica, so it's a bit hard to check right now...)

Other than the turbo, intercooler and Split second controller, are there any other parts (not accounting for plumbing and such) that I'll need?

[neale_rs]

Your D35 with alloy shafts will most likely hold up just as well as it does now.  This is because in your wheeling environment the torque load on the axle is limited by the mud (lack of traction) more than by the engine torque.  For rock crawling it might be different although at low speeds the turbo might not be doing much anyway.

[sharpxmen]

yes, your AFPR was preset to 46psi
your 19# injectors will not be enough, for 8psi of boost you will need  27lb/hr at a minimum, i would say 30 lb/hr is a fair estimate (you can tune it with the AFR for more or less fuel).

You will need a way to tune your engine, a wideband O2 and an rpm logger (if you can one that has both then you save some money) and also you might consider either a programmable O2 sensor (like the innovate one, which is also wideband and can log your AFR) or a signal modifier/enricher for your O2 so you can alter the O2 output based on boost - i would maybe call SSecond and ask them if they have a unit that does both (alter/program the MAP output and also alter the O2 output) - you want to be above 14.7AFR when in boost but unless you use something like i just mentioned you can't really fight the PCM in closed loop. I would also look at AEM FI/C unit, i think that has these features built-in, i came across it after i bought my split second unit.

[RT]

the d35 should be ok, but they stopped using the ax5 in jeep models with larger, more powerful engines because it has a bad habit of ripping itself apart even when running with a larger (4.0, 4.2) stock powerplant. It's a 'lighter' duty transmission being used in a 4x4 truck. IMHO I'd upgrade it because unless you baby the hell out of it you'll probably break it.

[jfrabat]

Your D35 with alloy shafts will most likely hold up just as well as it does now.  This is because in your wheeling environment the torque load on the axle is limited by the mud (lack of traction) more than by the engine torque.  For rock crawling it might be different although at low speeds the turbo might not be doing much anyway.

Yeah, in my case, I need wheel speed, which means higher RPM's, so the turbo would work for my type of wheeling (not sure it would be a good idea for rockcrawliing) as well as for highway use (it IS 600 miles between Panama and San José!).

yes, your AFPR was preset to 46psi
your 19# injectors will not be enough, for 8psi of boost you will need  27lb/hr at a minimum, i would say 30 lb/hr is a fair estimate (you can tune it with the AFR for more or less fuel).

You will need a way to tune your engine, a wideband O2 and an rpm logger (if you can one that has both then you save some money) and also you might consider either a programmable O2 sensor (like the innovate one, which is also wideband and can log your AFR) or a signal modifier/enricher for your O2 so you can alter the O2 output based on boost - i would maybe call SSecond and ask them if they have a unit that does both (alter/program the MAP output and also alter the O2 output) - you want to be above 14.7AFR when in boost but unless you use something like i just mentioned you can't really fight the PCM in closed loop. I would also look at AEM FI/C unit, i think that has these features built-in, i came across it after i bought my split second unit.

So new injectors and a piggy back ECU; got it.  Now I will start quoting this...

the d35 should be ok, but they stopped using the ax5 in jeep models with larger, more powerful engines because it has a bad habit of ripping itself apart even when running with a larger (4.0, 4.2) stock powerplant. It's a 'lighter' duty transmission being used in a 4x4 truck. IMHO I'd upgrade it because unless you baby the hell out of it you'll probably break it.

That's the part that worries me; if I need to put in a new tranny, the cost will go much higher, and I am not quite sure I can afford it...

[sharpxmen]

i keep making this error over and over - i said "you want to be above 14.7 AFR when in boost" but i meant below - i was thinking "above" as in more fuel than when not in boost, anyway to make it simple you want to be richer than 14.7, that is too lean when you're in boost.

[RT]

Yeah, in my case, I need wheel speed, which means higher RPM's, so the turbo would work for my type of wheeling (not sure it would be a good idea for rockcrawliing) as well as for highway use (it IS 600 miles between Panama and San José!).


So new injectors and a piggy back ECU; got it.  Now I will start quoting this...

That's the part that worries me; if I need to put in a new tranny, the cost will go much higher, and I am not quite sure I can afford it...

I think they make a kit to strengthen the ax5, i'm not sure though...

[sharpxmen]

i don't think the turbo will brake the AX-5 any sooner than w/o it unless you drop the clutch on it - will most likely fail at some point either way. In my case 1 synchro went out, i could still drive it no problem just had to shift more carefully in 3rd. I had no problems with 5th as most reported that to be a weak link, but i have to admit i didn't use it too much.

[Torch_Ind]

I have blown fifth just cruising down the highway lol.. was driving then all of a sudden and rotational crunch crunch crunch went to 4th silent went back to fifth crunch crunch crunch hummm going back to 4th silent humm guess were driving home in 4th lol

[RT]

mines just straight noisy, but i also have standard gl5 oil in it so that could be it

[sharpxmen]

I have blown fifth just cruising down the highway lol.. was driving then all of a sudden and rotational crunch crunch crunch went to 4th silent went back to fifth crunch crunch crunch hummm going back to 4th silent humm guess were driving home in 4th lol

you just need bigger tires, that way 5th will last forever...

[RT]

you just need bigger tires, that way 5th will last forever...

i like the way you think...

[Jeffy]

The 5th gear issue has a simple solution, don't downshift from 5th and you shouldn't have this problem.  And if you do be sure to rev-match.

[sharpxmen]

The 5th gear issue has a simple solution, don't downshift from 5th and you shouldn't have this problem.  And if you do be sure to rev-match.

why would downshifting to 4th would be affecting 5th? not sure how that works (i don't understand the mechanics behind it)

[Torch_Ind]

mine was just cruising in 5th I had been in fifth for probably a hour or so when it just spit chunks!