|
Dennis,
I spoke with Tracy Friday, and he said somewhere
between 13 and 16 inches was the magic number. That means straight up like
I was thinking won't work. So I bought some 1.25 plastic tubing to mock
things up, and decided up and over the engine will mean I can't use the stock
fuel rail, and the oil injectors will probably also be in the way.
So here is my next plan. I think there will
be plenty of room to the outside (and also forward or rear) of the
manifold. So I am going to see if turning the tubes 90 degrees so they go
left, toward the cowling instead of right over the engine. This should
give me 13 inches on the outbord two and 16 inches on the inboard two. I
think it should all fit nder the cowling, but I can't proceed without my engine
mount and exact measurements.
If I turn the pipes straight out, I'll need about
10" from the intake manifold face tot eh cowl. If I on't have that much, I
can angle the pipes for or aft and make it fit.
By doing this, I can use the stock fuel rail and
oil injectors. I'll have to add the pressure regulator, and that should be
all.
Chris
----- Original Message -----
Sent: Saturday, December 10, 2005 10:40
PM
Subject: [FlyRotary] Re: Intake manifold
length question
Chris,
I had the cut off RX-8, 4 port manifold at
the Rotary Roundup. The second rotary valve above where you and I
cut the intake manifold off is approximately 13 inches from the engine intake
port. With the throttle wide open that valve would be open
and connect all the intake tubes together. Most "tuned" length
suggestions I've seen in the past have been 20 to 25 inches. From talking to
people using these lengths they don't feel they have increased power due to
the dynamic effect.
If I were building a "tuned" intake I'd duplicate
the 13 inch length used by Mazda in the RX-8 intake. As you can guess
that would put the intake "box" on top of the engine. With a James cowl
it will be very tight above the engine. For my first intake I am
building a rectangular box that will be brazed to the intake just above the
injectors. It will extend forward and bend down as it goes
forward. I have a 65 mm Mustang throttle body I plan to use at the front
end. I'm about half finished with it and if I ever get to where I can
easily post pictures I'll send some.
Sorry for the slow
response. I've got plenty of excuses but don't think any are good
enough!
Dennis H.
the mallorys wrote:
After talking to
everyone at the Rotary Roundup, I came away thinking I was going to use the
bottom half of the stock Renesis intake, then put curved pipes up and over
the engine and put the plenum on the right. Now that I have it cut and
sitting in front of me, I am wondering about the lenght of the tubes.
The botom half already gives me about 7.5 inches of tube. Then if I go
over the top, I'm looking at another 16 inches.
My question for today:
Can I just put the
plenum right on top of the intake manifold, and run the pipes up into
it. There is 3.75 inches between the top of my manifold and the fuel
rail holes. I could attach the rail to the top of the plenum, and
I wouldn't have to mod the fuel rails at all.
I seem to remember the
consensus was that the length of the tubes didn't seem to matter all that
much.
What do y'all
think?
Chris
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
|