Building TURBO system for YJ

[TurboMinivan]

Your fabrication skills are beyond reproach, and my hat is off to you.

However:

3psi won't need anything.

This (somewhat common) misconception is completely incorrect, and it will lead to your engine's demise if you follow through with it. Your OEM speed density setup has no way of seeing any pressure above ambient, nor can it see the additional airflow a compressor provides... which means you won't get any additional fuel when needed. Even a mere 3 psi will be pushing about 20% more air molecules down your throttle body, which is sufficient to wreak havoc with your air/fuel ratio and cause damage. I remember laughing at a number of STS early adopters who threw a turbo on their LS1 F-bodies but didn't alter their fuel system "because the mass flow sensor will do that automatically"... only to watch their engines detonate and blow up at low single-digit boost. (One guy didn't learn, spent big bucks rebuilding his engine, then blew that one up again for the same reason.)

Please don't do this.

 

[I Lean]

This (somewhat common) misconception is completely incorrect, and it will lead to your engine's demise if you follow through with it. Your OEM speed density setup has no way of seeing any pressure above ambient, nor can it see the additional airflow a compressor provides... which means you won't get any additional fuel when needed. Even a mere 3 psi will be pushing about 20% more air molecules down your throttle body, which is sufficient to wreak havoc with your air/fuel ratio and cause damage. I remember laughing at a number of STS early adopters who threw a turbo on their LS1 F-bodies but didn't alter their fuel system "because the mass flow sensor will do that automatically"... only to watch their engines detonate and blow up at low single-digit boost. (One guy didn't learn, spent big bucks rebuilding his engine, then blew that one up again for the same reason.)

Please don't do this.

Not that I'm disagreeing, since I really don't know...but what happens if you drive your YJ to sea level? That's essentially what he'll be doing by adding 3 psi, right?

 

[MikeGyver]

What do you mean? Of course it can read pressure above ambient, ambient is not 1 bar (103kpa) at this elevation, it's only 85kpa. All of the maps in the speed density system go to 1 bar.
I'm going to have a wideband 02 sensor on it to monitor the AFR and tune as necessary, not just run it blindly; and I might even put a knock sensor on it too and monitor that.

 

[BlueWolfFab]

Hope I'm not cluttering the thread at all (if I am say the word and I'll delete)

but my dirtbike has this 1/8" fuel line running into it with a dial-a-jet fitting. In your case you could just plumb into the fuel rail for it I'd bet. Just a thought.

 

[BlueWolfFab]

Then again thinking more about it maybe your computer would just counter-act that and de-fuel the injectors? I dunno.

 

[MikeGyver]

That's fairly similar to what the FMU does that I'll probably be using. It uses a boost referenced diaphragm to restrict fuel flow in the return line, thus raising the rail pressure when under boost, and it does so at a aggressive rate so it not only provides additional fuel for the boost, but richens the AFR as well.

The computer doesn't control WOT fueling directly through closed loop. WOT enters open loop fueling and is controlled by the fueling maps/parameters.

 

[RogueJeepr]

I've always wondered about "jeeps" computer system. Does it not allow for mods such as cams, ect.
I used to be a 2.5 owner and wanted to do something like this but was met with comments such as just get a 4.0ltr or V8 swap.

 

[TurboMinivan]

what happens if you drive your YJ to sea level? That's essentially what he'll be doing by adding 3 psi, right?

Not exactly. The problem is that forced induction needs richer mixture at WOT than a naturally aspirated engine.

All of the maps in the speed density system go to 1 bar.

Right. It's just that you'll need more fuel than that gives you.

Oh, and that raises another possible point of caution. I don't know the specs of the turbo in your photos, but are you certain you can wastegate its output down to only 3 psi max? Over the years, I did a lot of experimenting with both the Mitsubishi TE04H as well as the Garrett T03 stock turbos on the Chrysler 2.2/2.5 engines. At different times, I ran each one with the wastegate arm disconnected, allowing the (internal) wastegate valve to flap in the breeze as it were. In both cases, I'd still get 5-6 psi of boost at WOT.

I'm going to have a wideband 02 sensor on it to monitor the AFR and tune as necessary, not just run it blindly.

Okay, that's good to hear. I used to run an EGT gauge for the same reason. Either method can work well.

The computer doesn't control WOT fueling directly through closed loop. WOT enters open loop fueling and is controlled by the fueling maps/parameters.

Chrysler's '80s turbo cars operate the same way. When I ran more boost than the OEM 2-bar MAP sensor could recognize, I'd have to manually add more fuel to compensate.

I used to be a 2.5 owner and wanted to do something like this but was met with comments such as just get a 4.0ltr or V8 swap.

That's unfortunate. Turbocharging can be a lot of fun. I think everybody ought to try it at some point.

 

[MikeGyver]

At only 1 bar of absolute pressure you won't need to richen the mixture, probably even without an intercooler. On a normal turbo car pushing like 2 bar of abs. pressure, sure. I will need to run 91 octane though, (93 would be better since that's the level of premium fuel at sea level locations but I don't think you can get that anywhere around here).
I also added a 1/8" NPT bung to the intake pipe specifically for a methanol injection nozzle in case the IAT's get high enough that they're causing issues when it's pushing 7psi, and I'm planning on running a MSD 6 BTM ignition box which can pull timing according to boost.

I've never really been a fan of internal wastegates, but I'm going to try to make this one work before I give in and buy an external gate. If the wastegate wont bypass enough flow to make only 3psi I'll maybe try porting it or just skip the 3psi phase and go right for 7psi. This turbo is actually significantly more HP capable than my expected level (I'm operating it on the very low end of the compressor map), so i'm hoping the gate will be large enough to maintain of boost at low levels since the overall flow is low for the housing.
The actuator is set for ~1bar of boost I believe, so I'm planning on needing to modify that, but I've got a simple plan that should work well.

Doing a V8 swap is just a pain in the ass in a short lightweight vehicle. The "practical" thing to do would be swap in an entire 4.0L drivetrain and wiring harness from a YJ,
but a turbo'd engine is just SO much more fun to drive. I honestly like the 2.5L it just needs a little bit more power for the freeway, and partly I just want another fabrication project before school starts.

 

[TurboMinivan]

... probably even without an intercooler.

Are you planning to not run an intercooler? Even at low single-digit boost, an IC is very worthwhile. As I'm sure you know, the IC will let you make more power and torque at the same boost level, plus it will keep charge temps in check and thus eliminate the need for methanol injection. An air-to-air unit is an 'install it and forget it' device, and would not need any constant monitoring/upkeep as would an injector. (Sure, you could say I'm splitting hairs here... but, still.)

I've never really been a fan of internal wastegates, but I'm going to try to make this one work before I give in and buy an external gate.

I fully understand. Internal wastegates are an accountant's decision; external wastegates are an engineer's decision. An external wastegate becomes an advantage when you're building an all-out race car where every last horsepower counts. For a street-driven vehicle at such low boost, I think the simplicity of an internal wastegate makes it a better overall choice.

If the wastegate wont bypass enough flow to make only 3psi I'll maybe try porting it

This was common on the '87 and '88 2.2L engines with the stock TE04H turbo. Once guys would open the exhaust, the wastegate often couldn't flow enough air to prevent boost creep. Once the passage was opened up as far as it could be while still being (barely) fully closed by the wastegate valve, the creep was usually eliminated.

but a turbo'd engine is just SO much more fun to drive.

This is why I say everybody should try turbocharging at some point.

 

[MikeGyver]

 

[gorillaxj]

Looks good! Love your fab work. Looks like you have good amount of room to use.

I run a FMU on my turbo 22re at 8psi max, don't have an intercooler either. So far it's working well. I was going to mention an FMU earlier but I for some reason thought the jeeps didn't have a fuel return line? I don't remember my 4.0 XJ having one...

Either way fun project and I always enjoy watching these kinds of builds.

 

[MikeGyver]

You can see the fuel return line and regulator right under the blow off valve in that last picture.
What brand FMU are you running? I'll probably go with a Vortech. How much difference does 8psi make on your setup?

 

[Rot Box]

So cool! Love the updates

 

[TurboMinivan]

Is that exhaust flange stainless steel?

 

[MikeGyver]

yap

 

[gorillaxj]

Awesome, yep it's there! Lol. My 2000xj didn't have one If I recall properly.

I am running a Vortech, found it used for 60$ and a full rebuild/tune kit is still available threw summit. Pretty good peice seams to work well. Currently Running a 10-1 ratio which leaves it pretty rich when spooled. (trying to stay on the safe side)

It is night and day, not an incredible amount but it doesn't bog going up Sandy hills or struggle to accelerate in high range like it used to. I have a Toyota CT26 on it and in double low it doesn't create boost, in single low it does and pretty quick. It's mostly noticeable in high range and single low. Which is right where I wanted it for wheel spin and powering up hills/sand ect. It really wakes up the 22re when I need to keep up or throttle threw with momentum. I personally love it. I dream of a compact water-air intercooler but haven't felt the need to jump it to the top of my priority list.

 

[BoostedRNR]

My turbo 22re was a blast to drive after I manual swapped it. I was pushing 10-12lbs, but had the rte fueling and efi

 

[TurboMinivan]

yap

Please forgive me for asking (because it is difficult to tell from your photos), but did you make the flange's bolt holes sufficiently oversized to allow for thermal expansion?

 

[MikeGyver]

Yeah, the bolts basically wobble in the holes. I calculated the thermal expansion difference to be around .014" worst case scenario along the long axis of the bolt pattern. It's a non-issue unless your flange is like a foot long or longer.