Semi- H.o. Swap

[jpnjim]

I looked through some old threads,

and I forgot to mention the distributor (again)

 

I never bothered to research if it made any difference, or not,

but to be on the safe side, I pulled the HO distributor out, and used the Renix one when I did the swap.

 

And don't forget you have to use the HO throttle cable.

Renix just doesn't reach

 

I also needed to swap in an HO gas pedal to get full throttle,

I had one, so I didn't try to modify the Renix pedal.

 

Some threads;

http://comancheclub.com/topic/26267-renix-to-ho-swap/

http://comancheclub.com/topic/26844-swapping-a-1995-40l-into-an-88/page__hl__renix#entry276885

http://comancheclub.com/topic/16812-late-model-intake-swap-caution-renix-content/

Talks about gas pedal;

http://comancheclub.com/topic/22644-ho-head-swap-questions/page__hl__renix#entry237533

[1987Comanche]

Renix vs HO flywheel. On Renix the teeth are positive (they stick up). 3 sets of 20 teeth with a space between each one. HO flywheel teeth are negative (slots milled in the flywheel). Spacing is virtually identical. 3 sets of 20 slots with a space between each one. I have my engine out right now and the flywheel is on the ground. I can put up a pic of Renix flywheel if you need it.

[cruiser54]

Here's the easy way to do it. Simplicity was the key word, right?

 

Cruiser’s HO into Renix Swap

This swap is easier than some will lead you to believe, generally those who have never done it. Those of us who have done it, like myself, will share with you the things that need to be done for a successful swap. Just think of it as swapping in a long block.

The HO and Renix have some differences but none that can’t be overcome very easily.

Any HO engine from an XJ or ZJ through 1998 can be used. One running change was that the rear of the head was no longer drilled and tapped for the temperature gauge sender beginning in the 96 model year. The sender can be relocated to the threaded hole in the thermostat housing taken from the HO engine. You’ll have to extend the wire to that location. Some brave souls even drill and tap the HO head for the sender.

You will be using the intake and exhaust manifolds from your Renix, along with all your sensors and wiring. Since the intake ports of the HO are slightly different, you use the Renix gasket. Exhaust ports are identical.

You will need to use your Renix distributor as it is different than the HO because they use different fuel management systems. The flywheel or flexplate from the Renix must be used so your CPS gets the correct signals. The valve cover from the Renix allows you to keep your CCV system intact and requires no modifications.

The HO block will have a plug in the coolant galley on the driver’s side of the block, closest to the front, which needs to be removed so your Coolant Temp Sensor can be installed in it’s place just as it is on the Renix. It requires a 5/16” square drive or a modified 3/8” drive that has been ground down to fit. Do this before installing the engine.

As for the knock sensor, which is located just above the oil pan on the driver’s side of the engine about mid way, all the blocks I’ve seen are threaded for it. If not, I’ve heard they may be drilled but not tapped. Tap the hole if that’s the case.

 

Revised 07/24/2012

[jpnjim]

^^^

This has been done,

but calling the port difference 'slight' is a stretch.

 

See the carbon marks on this HO intake?

It was used on a Renix head (opposite of using the Renix intake on an HO head, but same mismatch in reverse)

It shows how much higher the HO ports are vs the Renix's

 

 

from this thread;

http://www.jeepsunlimited.com/forums/showthread.php?t=450854

 

 

This pic shows how someone tried to open up the Renix intake so top is more square (like HO intake above)

Image Not Found

 

Notice how the top part of the Renix intake is a completely different shape?

(bottom pic is stock unmodified Renix intake, modified Renix on top)

 

 

So you certainly can bolt the Renix intake to the HO head,

 

but I'd spend the $ for a head gasket & a valve job

to keep the Renix head with the Renix intake

before I'd bolt a Renix intake to an HO head.

 

[HOrnbrod]

^^^

This has been done, but calling the port difference 'slight' is a stretch.

 

So you certainly can bolt the Renix intake to the HO head, but I wouldn't.

 

Me either. Makes no sense, it's like semi-polishing a turd. Good pics Jim, they show the choked Renix intake intake ports clearly. What is gained by using an HO head on a Renix if it can't flow as designed? If you are going to do an HO swap, do it right by swapping in the HO harness, intake, TB, HO sensors, and ECU from a donor. A semi-HO swap is a real half-azzed idea IMO.

[jpnjim]

 

 

Me either. Makes no sense, it's like semi-polishing a turd. Good pics Jim, they show the choked Renix intake intake ports clearly. What is gained by using an HO head on a Renix if it can't flow as designed? If you are going to do an HO swap, do it right by swapping in the HO harness, intake, TB, HO sensors, and ECU from a donor. A semi-HO swap is a real half-azzed idea IMO.

 

I don't like the mismatch for a couple of reasons,

the high port HO head is optimized for (relatively speaking) a higher rpm band than the Renix intake.

 

Say you have a head optimized for (made up numbers) 2800-4800rpms

and an intake optimized for (again I pulled these #'s out of my A) 1800-3800,

each individual parts optimized 2000rpm wide powerband now combine to mismatch that is sort of optimized for the narrow 1000 rpm band were both parts are 'working'.

 

^^^ oversimplification but it explains why mixing & matching parts can hurt both upper, and lower rpm power.

 

You can't put a tunnel ram on grandma's stock Buick,

and putting on a 2 bbl intake won't make a stump puller out of a race engine.

 

The other thing is a mismatch like a smaller, in this case, odd shaped intake on a bigger rectangle port head puts all kinds of turbulence in the port.

And probably not the good kind to induce fuel atomization,

but the bad kind that chokes off flow, and can do other nasty stuff.

 

As far as doing the full-full HO swap (computer & all)

hopefully that's in my future,

but there are a lot of things on that to do list.

[HOrnbrod]

It all boils down to maximizing suck and blow to get the best balance of power, efficiency and economy. Never ending battle, but it's fun with a stroker. :yes:

[ftpiercecracker1]

. . . but it's fun with a stroker. :yes:

 

 

agreed. :D , 7120 head + bored TB + (99 - 04) intake = a WHOOOLE mess of fun

[cruiser54]

I've only ever done the HO into Renix swap but I can tell you, the difference in ports was nowhere near as different as shown on the HO manifold to Renix head.

Maybe 1/4" at most difference. Not much different, if any, than the differences in stock intake to head ports on factory engines. This is a good swap for guys with limited funds/experience based on the availability of good used Renix motors.

 

That said, I have a confession to make. After the first one, I have port matched my Renix intake to a Renix gasket and the HO head to the Renix intake gasket.