H.O. Head swap?

[kyleag89]

I was wondering if swapping the H.O. head on my 89 4.0 would be worth it. Also is there a good write up somewhere on this? I tried searching with no luck.

[Oizarod115]

no, its not. IMHO. especially if you don't already need a head-gasket or other motor repair.

[kyleag89]

Does the H.O. head offer better compression than the Renix?

[Oizarod115]

nah, and any power gain is negligible. the renix 4.0 is rated for 177hp and the HO is rated at like 190hp. (and that may also be due to the computer system, but you'll note that renix rigs typically get 2-5mpg better gas mileage.)

but the renix makes its power nice and low in the RPM range, the HO makes its power higher up. (less useful in a truck)

 

the amount of stuff that changes from renix-HO is ridiculous

you'd need new intake, exhaust all the way to the converter, fuel lines, TPS adapter, you'll lose EGR, the serpentine belt system changes, different power steering pump/lines.

 

really not worth the headache IMHO

[kyleag89]

Yeah doesn't seem worth it at all. Thanks for your response.

[ratrapp]

yeah,i did the swap and even used the 99-up style intake with a 93 ho head.i spent a couple hundred dollars and all i succeeded in doing was fixing my oil leaking head gasket.i laso believe the power increase from a ho is mostly in the pcm and electronics of it.

[carnuck]

Want to get the oomph of the HO in a Renix? Put the HO injectors in.

[kyleag89]

I have 95 HO injectors in my MJ now and noticed no difference at all. :dunno:

[carnuck]

Clean the vacuum hose for the MAP sensor with TBI spray.

[dakineJ]

But then again ... with additional mod's you open yourself up for more gains. Think of it as a package deal. Just the head swap, not so much. Add to HO, 91-95, heads better flow the right header and 99+ intake, CAI, the right injectors and TB, good ingnition and free-flowing exhuast, and more it start's to add up. Look at your motor as a big air pump. The better it breath's, the happier it is. Then you can start getting into gearing, and it continues haha ... it just depends how bad you want it.

[ratrapp]

i don't know about all that.i did the swap with a 93 ho -head fresh out of the machine shop.i used a 99 up intake,ho style tb and already had the newer style 4 hole injectors and used the mopar mls head gasket that is a few thousands thinner than the paper gasket.i didn't really notice any extra power.i didn't swap the from renix style exhaust manifold so maybe that's holding me back.we'll find out soon since my atp ho style header and downpipe and new o2 sensor just showed up yesterday afternoon.so we'll see if that's what's holding me back.i already had a 2 1/2 exhaust and 2 chamber flowmaster and k&n filter on the truck.strangely when i changed the exhaust,air filter and switched the axles and transfer case fluid to redline synthetic i did feel a slight difference in mpg and power,but not with the head/intake change.