H.O. motor with Renix stuff?

Hey I just blew the motor in my 1990 xj and was wondering if I can pull a motor out of any xj or does it have to a Renix motor to just bolt up. Im pretty bew to Jeeps so please excuse me if this a retarded question lol.

Meanie5470 said:

Hey I just blew the motor in my 1990 xj and was wondering if I can pull a motor out of any xj or does it have to a Renix motor to just bolt up. Im pretty bew to Jeeps so please excuse me if this a retarded question lol.

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Yes you can use any motor so long as it is a pre 00' and doesn't have the coil packs. Just bolt your intake and sensors to the new engine. You will also have to use your old motor mount ears. There may be a few other various little pieces but you will still have your old engine to pull them off of if you need them. Also, the later models don't have temp sensor in the back of the head so you can use the one in the t-stat housing is what I did.

same happened to my '90 and my cousin put an engine from a '98 cherokee in it. runs great

Is there any difference internally? Should I expect any sort of a performance difference? I know the H.O.'s had a little more power but was that all from the computer?

They have a different head design and cam grind...there may be more differences but I don't know them right of hand. When bolting your renix intake to the ho there will be a slight misalignment but nothing that really effects performance. (I know this because I ran my renix manifold on my 99' for a while) You can use the later model intake but you will need to adapt the throttle body, put all of your old sensors on the new intake, and zip tie your injector connectors to the new fuel rail. I did the 99+ conversion on mine and adapted an ho throttle body and all of my old sensors to the new intake. I also had to tig weld another bung onto the 99+ fuel rail beacause it only had one and run an inline rising rate fuel pressure regulator. If you go the 99+ conversion route you will also need the ps pump and braket that work with the new manifold.

Also if you look at a 99' engine stay away from the 0331 casting number head. Incase you don't know where to find the number it is located between the #3 & #4 cylinders next to the valve cover on the drivers side. They are prone to cracking...

yea I dont plan on doing a 99+ swap. I honestly just want a motor that will bolt up and not have any issues. Swapping an intake is no big deal but I want to keep is as straightforward as possible. When you say "misalignment" do you mean with the bolt holes?

No the bolt holes line up perfectly...it's a misalignment in the head's port and the intake runner's port. It's not a big misalignment...it's just that the bottom of the intake runner sits a little lower then the bottom edge of the head runner causing a slight ledge or step up between the intake runner and the head. It really doesn't effect performance on a stock engine...none that I could tell anyway. Hope that was a good enough description and I didn't confuse you.

Nah I got ya. Thanks for the info.

jeepboy381 said:

The Misalignment of the intake too the head of the engine is really bad in my opinion. I ran a H.O. motor with the pre HO "renix" intake for 5 months then I swapped in the H.O. intake, I could tell a very noticeable difference. I had a very noticeable power increase, better fuel mileage, and the sound of the exhaust was much louder. The louder exhaust had to do with the lack of air the engine was sucking in with the renix intake. You can use your old manifold but it will run much better with one that lines up correctly. People spend hundreds of dollars to get the head ports matched to the intake ports precisely for more power, even though they are lined up pretty close by the factory. I don't think you want a 1/4 inch lip sticking up blocking your airflow.

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You are proabably correct the renix manifold on the ho is less than ideal. However, I ran this setup and couldn't tell that much diference when I switched...albeit my butt dyno isn't that acurate. The renix manifold still ran fine, idled good, and had power. If you don't want the ledge run the later model log style and make the later model ho throttle body work, or you can buy an adapter (forgot who make it) and use the renix throttle body on the later intake. Just use the later model fuel rail too and either zip tie the injector connectors to the injectors or splice the news connectors to the old renix system.