Firing order on a K series...

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 02, 2007 11:34 pm

Working on a theory...

Direct head throttle body sets cost a fortune.... I know someone who can make anything from stainless...

Theoreticaly. using two std rover throttle bodies on a two peice intake manifold.. one side feeding two cylinders. etc...

Thottle position sensor from one body feeding std ecu solid linkage to second throttle body...

use std fuel rail...

Discuss?

mac · Post by **mac** » Mon Jul 02, 2007 11:42 pm

A) two standard TB's using a TPS for fueling would require a remap (twice as much air - not enough fuel)

B) Length of inlet tract - probably too small, as one valve opens the other could be snapping shut setting of ripple of air backwards which could suck air out of the other chamber rather than let it go in

C) Physical distance - can you fit it all in + air filter?

Mac

Post by **campbell** » Mon Jul 02, 2007 11:42 pm

"What d'you wanna go do that for then, matey?"

!!

woody · Post by **woody** » Mon Jul 02, 2007 11:45 pm

and one of the main benefits of throttle bodies is the straight inlet tract.

Victor Meldrew · Post by **Victor Meldrew** » Mon Jul 02, 2007 11:50 pm

mac wrote:A) two standard TB's using a TPS for fueling would require a remap (twice as much air - not enough fuel)

B) Length of inlet tract - probably too small, as one valve opens the other could be snapping shut setting of ripple of air backwards which could suck air out of the other chamber rather than let it go in

C) Physical distance - can you fit it all in + air filter?

Mac

Thinking long smooth admittedly curved inlet, equal lenght. Longer length for better torque.. good point on the throttle position.. so I would need an emerald.
as for space... there is a fair bit of room and the filters would go into the wheel arches.

Victor Meldrew · Post by **Victor Meldrew** » Tue Jul 03, 2007 4:47 am

something shaped like this but one on each side with throttle body at each end?

hiscot · Post by **hiscot** » Tue Jul 03, 2007 7:11 am

anythings possable

Rich H · Post by **Rich H** » Tue Jul 03, 2007 8:03 am

How about a nice set of carbs?

Motorbike throttles not be cheaper?? You still need the manifold making up.

BiggestNizzy · Post by **BiggestNizzy** » Tue Jul 03, 2007 9:12 am

If your going to all that trouble surely making a set of throttle bodies from scratch would be an idea, with variable length trumpets

robin · Post by **robin** » Tue Jul 03, 2007 9:23 am

The firing order is 1-3-4-2 IIRC. So that's also the order the intake valves open in, so if you want to common up two cylinders on a manifold it's 1&4 and 2&3.

Given that you can get to 170BHP on the standard plastic plenum and better on the alloy plenum (though at some small cost to the lower end) I think you would do better to get your head flowing more air (cams, valves, porting and chamber mods).

As you open up the intake with bigger tracts, multiple throttles, etc., you slow the air speed; coupled with the weedy intake valves you get worse performance at the lower end of the rev range, especially if you plan on fitting wilder cams at some point. Your dual manifold would certainly make the wilder cams less of an issue.

Performance is ultimately limited by the length of the pipe the other side of the throttle; the alloy plenum is a good compromise because it allows the 90 bend to happen with maximum radius while still having a straight(ish) long pipe on the other side (consider the whole plenum body and the air filter-to-throttle pipe to be a single straight line, when on full throttle).

To get really good performance from multiple throttles, you need not only straight pipes from throttle to head, but straight pipes from air intake to throttle. Most of the big engine upgrades for S1 sacrifice some of the boot space to get long ram pipes inside an even bigger airbox.

It turns out that 180 degree bends in the pipes can be effective also, provided the radius is not too sharp (the plenum designs all have >90 degree bends in the pipes to allow the plenum to sit above the pipes).

So if you wanted to make a performance inlet manifold I would look at the ports on the head (whether or not ported) and shape your new intake pipes to match exactly (or radius out the ports on the head to match the intake pipes), then stagger the bend in the pipes such that each is as close as possible the same distance from the throttle(s), then feed into a plenum chamber that is designed to take a 52mm or even 56mm throttle body. You want to avoid steps in diameter (blend from one diameter to the other over a run of pipe instead) and 90 degree pipe-to-void interfaces.

Take a look at the Honda and Toyota intakes - they make 200+ BHP on a single throttle quite happily.

If you know anyone that has the suitable CAD/CAE tools required, you could model it and get some airflow simulations done on it. Failing that, build it and get it lashed to a flow bench somehow (you would want to compare to a plenum for good measure).

Cheers,
Robin

Victor Meldrew · Post by **Victor Meldrew** » Wed Jul 04, 2007 12:15 pm

Isn't the honda throttle about 80mm.

Was thinking that you could up rather than sideways with the manifold. I remember the mini with the down draught webber set up.

You would need a spare boot lid before you started hacking away for a clearance hole.

Rich H · Post by **Rich H** » Wed Jul 04, 2007 1:32 pm

A nice big boost tube like some 340rs or MR2s?

GregR · Post by **GregR** » Thu Jul 05, 2007 1:11 pm

RICHARDHUMBLE wrote:A nice big boost tube like some 340rs or MR2s?

might not be too bad an idea if you can make it a sensible spec for the ram air effect into the TB. Bet it would look fugly though!

Blaque · Post by **Blaque** » Thu Jul 05, 2007 2:56 pm

GregR wrote:
RICHARDHUMBLE wrote:A nice big boost tube like some 340rs or MR2s?
might not be too bad an idea if you can make it a sensible spec for the ram air effect into the TB. Bet it would look fugly though!

I was toying with the idea of fitting the "cowling" bit from a Huricane induction kit, and slightly shortening the standard "consertina" tube to a standard air box with an ITG Profilter.

Worth doing?

I may be blaspheming here, but I felt that with the huricane fitted the car didn't pick up from low revs as well as it did with a standard airbox.

\Heretic

Rich H · Post by **Rich H** » Thu Jul 05, 2007 3:00 pm

Can if you want, doubt you'll notice....