CHI heads and intake

Hey Will,

The CHI 218 ports as delivered:

w = 1.41"
h = 1.95
R1 and R2 = 5/8"
H1 = 3.36"


This information came from Dave at CHI about a year ago.

By Comparison, a 4V port is

w = 1 13/16"
h = 2 9/16
R1 and R2 = 9/16"
H1 = 3"

Of course, this all depends upon how the heads are ported, but if you are going to adapt a Hall intake to the CHI's you're in for a lot of work. You'll notice that neither the port width, or the height of the roof or floor line up. The high port version of the Hall intake would be slightly better but still a lot of work. Many believe that the old Ford high port heads are the same port height as 4V. Every one I've ever measured has H1 ~= 3 1/4".

I have a table of dimensions for various heads that correspond to the dimesional diagram below. Just haven't ever gotten around to posting it.



Hope this helps.

Kelly

Will,

Have you considered the CHI 4V heads? These are specifically designed for guys that don't want the hassle of changing intake manifold and they flow only marginally less than the 3V, unless you have a radical lift cam installed.

Thanks for the info guys. What I want to do is take a Quella IR injection system from an iron headed stroker and swap it to the CHI headed stroker. What is to be used to build the ports to match? Epoxy and a die grinder?
Will

Will,

Sorry, didn't realize from your first post you already had the 3V heads on an engine.

Kelly has good advice, believe me, I went through similar when I picked up a set of C302B heads and wanted to use my 48IDA manifold on them. I suggest you take Kelly's dimensions and draw out the two port sizes over each other, then it will be visually evident how much work you are in for. Also the Quella IR runner would need sufficient material up top to be able to port out the .36" to raise the intake port to match the CHI head port.

I can't believe Dennis wouldn't also sell an IR runner for aluminum heads, if so maybe he would be willing to sell or exchange your existing base IR runner for a high port version. That would at least get you a closer starting point. Again if the runners are independent (i.e. one per cyclinder head with a valley plate), then there may be more options to 'shift' the runner up and fab a new valley cover.

Good luck

Will,

What deck height block for the CHI engine? Is this going on a 9.2" Cleveland block?

Kelly

Will,

If I were looking at doing this swap, I would drop the additional cash needed to buy a set of the CHI 4V heads. The 4V head is a 3V head that has had the intake port opening tapered to the dimensions of the 4V port, so that it mates up directly with any 4V manifold. Other than the tapered opening, the intake port is identical to the 218cc 3V intake port. This would alleviate the need to modify the intake manifold for the IR system.

You are not going to notice a difference in performance between the two cylinder heads. Set the 3V heads on the shelf in case you decide the headache of owning an IR system is not for you. By keeping the manifold unmodified, it will be easier to sell if that day should ever come.

My advice for what its worth.

take care, cowboy from hell

quote:

If I were looking at doing this swap, I would drop the additional cash needed to buy a set of the CHI 4V heads.

This is exactly where I ended up, have a new set of 4V CHI heads here beside me and they are the exact dimensions Kelly gave for the stock cast iron 4V.

quote:

If I were looking at doing this swap, I would drop the additional cash needed to buy a set of the CHI 4V heads.

Good advice George. It would take less time to swap the heads than prep the manifold, and this way, it can still be applied to a 4V head Cleveland for which it was designed.

quote:

You are not going to notice a difference in performance between the two cylinder heads.

I would agree, but would add that you're unlikely to realize IR performance characteristics without a purpose ground cam.

quote:

.....the headache of owning an IR system is not for you.

Now, now, George; tuning is pleasure not pain!

All the best,
Kelly

What type of characteristics would an IR system require?
Damn! It definately makes sense to go with a set of 4V's but I wasn't looking to spend thousands on this...

What type of "cam" characteristics, I meant to write.
Will

quote:

What type of "cam" characteristics, I meant to write.

Will,

I didn't mean to suggest IR would necessitate a cam change. It's more a matter of optimization.
Like in all other engine combos, cam selection is driven by the other components in your build and the performance characteristics you desire.

But generally, IR can mellow out the low/mid rpm behavior of peaky cams. In other words, you can get away with running tighter lobe separation angles on the street (more overlap) and not suffer the reduction in idle quality and low/mid rpm performance to the extent that occurs in common plenum intake manifolds with the same cam. This tends increase max torque, moves the torque curve toward lower rpm, but can also narrow the powerband a bit. -All depends upon what you're after.

Kelly