1995 SR engine replacement, 3.8 bottom end questions, DOHC questions

[GeorgeK]

First of all I'm a newbie to this forum, but not cars/racing/offroading,

I've owned this 1995 SR for just a little over a year now,
I've done a Baja trip on it, replaced a ton of crap, made it my own.
Now its time to replace the motor due to bad valves after a timing belt failure and the compression on the other side isn't so great,

These are the two routes I'm taking with this, depending on what information I get:

1. Sorento longblock. Swap over electronics ONLY. This is the easiest route, just making it run.

2. 3.8 Shortblock with Sorento(read newer)DOHC heads. Stroker route, more power/torque. But this depends on one thing really, are the 6G75 blocks the same height? I don't want to mess with any custom timing belts.

Any advice on this?

 

[Salonika]

Keep it stock.

 

[PA_JERO]

I beleive oldcolt (on 4x4wire, dont think he posts here) put together a 3.8 DOHC engine. This is something I've thought about as well. Just like your talking, 3.8 block with SR DOHC heads. I'm not sure what write ups on this are out there, but this would be cool. You should have a decent amount of torque gain out of this.

 

[Fasteddy]

6g-74 (3.5) and -75 (3.8) blocks are the same height, 19mm taller than a -72 3.0. I would compare head gaskets, and be sure the cyl bore on the 3.5 dohc gasket doesn't overhang the larger bore of the 3.8. If so, you can get a custom copper gasket cut, which is a better gasket anyway, and is re-usable if you anneal it in the oven.

 

[GeorgeK]

I beleive oldcolt (on 4x4wire, dont think he posts here) put together a 3.8 DOHC engine. This is something I've thought about as well. Just like your talking, 3.8 block with SR DOHC heads. I'm not sure what write ups on this are out there, but this would be cool. You should have a decent amount of torque gain out of this.

Yea I've looked into that, but there are no details about his swap, no pictures, not even a full write up,

 

[normal_dave]

It appears the Aussies have it figured out: Except for you keeping the DOHC... and this swap is in a '97, but the information should be helpful.
http://www2.pajeroclub.com.au/forum/showthread.php?t=40816

 

[RyanY]

Another consideration - from what I understand, Montero 6G7x engines have forged cranks and the non-Montero versions of the engines have cast cranks. Not sure on the Sorento.

The DOHC heads on your SR supposedly flow better than the SOHC varieties, although I'd have to believe that you'd be able to obtain a broader torque curve if you were to swap to MIVEC-equipped (or the Kia equivalent) heads.

 

[GeorgeK]

Yea but then I'd have to figure out how to run the MIVEC, another headache, i just want a simple ish solution,
Unless I'm missing something,
I'd love having MIVEC

 

[RyanY]

I'd expect that something like this could be used to actuate the MIVEC system: https://www.summitracing.com/search/part-type/switches-rpm-activated

 

[GeorgeK]

I'd expect that something like this could be used to actuate the MIVEC system: https://www.summitracing.com/search/part-type/switches-rpm-activated

I wonder how that works, and if the ECU will be able to compensate for the cam timing provided by MIVEC,

That would be one heck of a rig,

 

[RyanY]

The OEM ECU wouldn't have anything to do with the MIVEC system, since it's not equipped for it. It will just read the air/fuel mixture as reported by the O2 sensors and hopefully be able to compensate for the additional necessary fuel. The RP switch would operate completely independently of the ECU to switch the MIVEC system.

 

[TerrenceLP]

Sounds cool, I would say aftermarket ecu or get the harness from the donor motor as it will run everything and can be Flashed -

http://www.tactrix.com/index.php?option=com_content&view=cATegory&layout=blog&id=36&Itemid=58&FontSize=font-large

Swapping for simplicity sake not going happen, devil in the details.

 

[GeorgeK]

Finally got the 3.8 longblock, pictures to come
Just need to start tearing it apart once the weather cools down. its 104 at the moment,

 

[PA_JERO]

104????

You should probably stay in doors.... weak.

I can't wait to see this action. Might be something I will consider as well.

 

[PacS14]

Keep us posted with the engine, temps here cool down... but now we're flooded is some areas.