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Teqnyck wrote:I don't mean to sound stupid, but I've always wondered why all aftermarket IMs for the KL engines have seperate plenums for front and back banks. it seems like it would be easier to make a box that sits on top of the engine, with 6 runners coming out of it. No?

Probably to keep velocity up.

lakersfan1 wrote:

Teqnyck wrote:I don't mean to sound stupid, but I've always wondered why all aftermarket IMs for the KL engines have seperate plenums for front and back banks. it seems like it would be easier to make a box that sits on top of the engine, with 6 runners coming out of it. No?

Probably to keep velocity up.

I dont know if this is true - but this is what i can think of ....

It is possible that 2 cylinders have overlapping intake phase - i.e. 2 cylinders from the front & back banks could be sucking air at the same time - if there was a box like IM then the cylinder closest to the TB would get more air than the other one....

Does this seem logical ....

Ok, I started to reply last night but got distracted.

The Mazda K serise is a single plane crank, put in simple terms
you have two three cylinder motors on a common crank.

Due to this the most common problem of most engine's
that of charge robbing from a adjcent cylinder is negated.

The most effiective design that ive played with utilises separate
banks for the front and rear, however my injectors are mounted
directly over the runner which is tilted over to match the port angle
hence i get a direct shot at the back of the valve.

A common plenum is fine, CZT second one, however the injection
mounting and positioning, is a complete compromise and would spend
a great deal of its time "wetting " the wall of the runner.

The greater the atomisisation of fuel in the air the greater your VE will
be, so its total bollocks to have a mirror finish on your inlet ports.

Going back to the "stainless Twin" the one on the purple rocker covers
which are quite sexy.

The plenum's are carried on past the ports towards the front of the motor
which is good practical design, 2 inchs seems to be the size for a klze.
The collector angle is not bad, quite smooth, however you want
the curve to finish 2 inchs before the start of the ports, not easy when
the ports are not inline.

Look at czt first one, the collector angle is brutal, way to much turbulance
around ports 5 and 6.

Common myth, air flows equally in a pipe,
Not true, air on the boundry of a pipe will flow slower then air at the
center, so stay the hell away from anything made with square tube
as there is a load of dead air just like a square port in a V8.

Note one set i did i cheated and used square, but reduced the volume
area, which restricted flow,

Also to be noted, with standard cam's a total runner lenght of 10" from
the valve seat to the top of the runner, gives good results.
Runners must always be a even lenght

( law of harmonic's don't ask but its proven on my superflow PC Dyno )
Exhaust systems can be odd, infact 35" seems to be the majic number

anyway my 2 cent's which is not even worth 1 cent US.

Thanks for the input, Kiwi. That explains alot!

Custommx3 wrote:

Custommx3 wrote:Another pic of what it looked like in later stages.

This one added 25 Hp.

Is this one for resale?

how does vris go on this or is it thrown out

Yeah, VRIS is completely ommitted on these types of manifolds.

so okay who here has this ..... how well does it work..... what about pvc pipes..... brake booster???? where does all the vaccum lines go????

PWRD_BY_HKS wrote:so okay who here has this ..... how well does it work..... what about pvc pipes..... brake booster???? where does all the vaccum lines go????

Brake booster can be taken of either the front or rear bank
Vacum line can be taken any runner and or throttlebody

For mysetup ive had to build a fuel trap to stop fuel getting into
the map sensor

( non standard ecu.)