Custom Intake

[Dr. Dyno]

So, aside from epic coolness what would a double throttle body intake do for the average xj?

Nothing that a single larger throttle body couldn't do from a functional point of view but then again, a double TB set-up would be a symbol of your creative genius that you could show off to your buddies and leave them with a jawdrop. :laugh:

 

[Rob Mayercik]

But the cool factor of multiples can not be denied. The ultimate, of course would be 6 small TBs mounted in a near horizontal orientation. Which I dimly remember as having seen the photos of. I think the guy used TBs off of a motorcycle but, could be wrong...

A 4.0 using a "Full House" TB config - goodness. If you ever find the pics, you must post that.

 

[bigdaddyjlove]

http://www.extrudabody.com/servlet/the-276/Kit-cln--Jeep-Inline-6,/Detail



Here you go

 

[CobraMarty]

 

[tbburg]

On the idle air control issue:

Could you fab up an aluminum bracket to hold a stock IAC motor mounted on the balance tube between the two TB plenums? 'Run a small(1/2") hose down from one of the intake tracts to pick up filtered air.

 

[John(XJ)Jeep]

You could drill a small hole in each throttle butterfly instead and block off the idle air bypass slots altogether.

Well there is none actually, I took the upper TB's from it. The bottom TB's had
all the plumbing on them. This is straight like the old mustang TB's without
anything on them. That was the way I was going to do it anyway cause there
is no room for plumbing on these TB's, the bypass would have to go to the
manifold instead. I think I'll end up drilling the butterflies because it's so much
easier. It'll be a last moment thing, I might change my mind again. lol

 

[John(XJ)Jeep]

What if you just modified one of the TB's to be closed at 0% throttle? As you give it the beans it functions like a normal TB, but it does not let air through at close?

Carburetors do that and it would be good for drivability issues, but that's something I'll keep in mind now, thanks.

 

[John(XJ)Jeep]

So, aside from epic coolness what would a double throttle body intake do for the average xj? I just don't see it except maybe in a heavily ported head w/ cam & stroker, but even then a 68mm tbody should do it?
Aren't you just way out flowing the head at this point?
But...
Epic cool.

This is what I'm building the intake for.

http://www.naxja.org/forum/showthread.php?t=1070907

 

[John(XJ)Jeep]

Here I've made the dividers for the runners and bolted up the TB's for mapping
out the linkage. You can see down the throat of one of the TB's. I tested with
water from the garden hose to see what the floor of the runners were doing, it
actually seems to be doing it's job properly with no disruptions but I can't test
the full port though. Maybe if I had some smoke to pass through it might be able
to tell a little more but oh well.

I'm going to see if I can finish the linkage today and start prepping the old XJ for
the gutification and get my exhaust and rear suspension started.

 

[Talyn]

Nice job, but is there enough plenum volume?

 

[CobraMarty]

That's kinda weird, you put a divider separating 2 runners from the other one, and then the TB sits kinda offset from the divider giving 3/4 of blade opening to 1 runner and 1 1/4 blade opening to the other 2 runners.
I would just leave the divider out. If effectively makes the one runner longer than the other two. Unequal length runners?

Still great work, maybe poor intake manifold science.

 

[John(XJ)Jeep]

I wasn't too sure about it, but without that divider air slams the flange. I played with it for a few days
without them there and at first I thought maybe the air will just find it's own path because it is being
sucked through rather than pushed. The more I played and thought about it the less sense it was making
so I decided to try and put dividers there. Did a little math to offset it and tried it out, seemed to work a
lot better but wasn't too sure so I also decided to keep the divider low so that air has a chance to "decide"
where to go. Same length idea but I'm sure they are not. But the variance will be so little it probably won't
matter enough for me to care.

The plenum size I don't know, should be bigger than stock really. I couldn't fit my hand in the log and when
I cut it up it was as thick as 1/4 inch in some places, it was a lot smaller than I thought it would be. By
looking at it I can tell you I got more plenum but how much I don't know. I guess I could measure it when
I get the other one out. Not hard, pour water in find out. I'll be sure to do that.

 

[CobraMarty]

It seems like always so many questions.
Look forward to your finished piece and your testing/evaluation.
This is all uncharted territory.
Great work.

 

[John(XJ)Jeep]

Ye, lots and lots of questions yet to be answered. I just dropped off my intake at my buddies
place there, he's gonna clean it up a bit for me. I currently have the Jeep up on blocks and
have changed out the motor mounts already. That engine looks like it's gonna jump out of the
engine bay! As I figured it was hitting the intake and not letting the hood close but ya I already
knew that but I think the new intake it gonna be higher up yet. So I'm just going to leave it
for now until the last thing.

I got some more pics but I want to save them for when I get the exhaust manifold out and
modified first.

 

[tbburg]

Any update/progress?

 

[John(XJ)Jeep]

Not too much of an update, I put it on hold for a bit to finish my exhaust and I
have a little to do on that tomorrow. Just needed a tweak on the routing of the
pipes then I get to patch the floor a bit then I can start on the intake again.
It is already on and everything is installed except for the intake tubes, throttle
cable, TPS. I still have some other things to rework a little but nothing major.