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If I am correct, we have 60mm throttle body's on our stock MX3s. Now, what if I was to put 70mm rubber pipping?
Would I loose power?
Rough idle?

Also, does it matter how long the piping is?

Reason why I am doing a custom CAI setup is because I have spare rubber pipping and I need to change my dirty air filter. Might aswell do a CAI setup

actually i found somewhere on this site where someone did a test of pipin size and he found that the 2 inch pipin was giving better cfm flow than with a larger intake pipe if i find it i will post it other than that i dunno bout the short pipe long pipe thing but there may be somethin that could be diff about them.

i woudlnt see a point in going any bigger really, all that really matters is how easy ur engine can suck up air through the filter, and how long it is i wouldnt see how that would make any dif, its a constant flow of air correct, its not like when you stop that the air stop s flwoing and when u go again u gotta wait for air to completely flow through ur intake to get to ur engine again
or am i wrong haaha?
just seems like common sense to me

jschrauwen wrote:I think it all has to do with the TB VAF combo in use and what was the OEM ID (inside diameter) that was used in those applications. We know what the ID of the flex tubing is for the K8 and I'm not aware of what diameter was used on the KL68 TB's and JE50 VAF's for the ZE's. WRT the K8, I think it would be best served to stick within the same ID as the OEM intake tube since the CFM flow generated by the TB to defect the VAF is supposed to be an accurately measured process. Changing that CFM based on a larger or smaller intake tube will noticably upset that carefully measured balance that assures a correct air fuel mixture. Too large, I would assume a lean mixture, and conversely, too small, a too rich mixture. In essence let's not mess with what highly skilled engineers have alreay figured out. IMO.

I believe the throttle body size for the KLZE's was 65mm? Or 67mm?
I think it is 65mm
Can anyone comfirm what jschrauwen?

K8= 55mm
ZE= 60mm

3" pipe is suffice.

Pipe diameter and legnth DO make a difference. As for your particular set-up I do not know what will give the most power. a longer pipe (up to a point0 will give more HP and a shorter (up to a point) will give more torque. No one here has ever had the time, money or been bored enough to sit down and tried several different legnths and diamters on the dyno.

I'd suggest no more than 2.5 diameter on a K8 and no longer than about where the stock intake box sat.
As for a ZE I have a 2.5" now and I will try a 3" later this year to see what the differences are, but I have a pretty good feeling that a 3" will work better.
PS, I have a straight neck ZE intake, JE50 MAF, and KL31 TB (stock ZE staight neck)

PATDIESEL wrote:Pipe diameter and legnth DO make a difference. As for your particular set-up I do not know what will give the most power. a longer pipe (up to a point0 will give more HP and a shorter (up to a point) will give more torque. No one here has ever had the time, money or been bored enough to sit down and tried several different legnths and diamters on the dyno.

I'd suggest no more than 2.5 diameter on a K8 and no longer than about where the stock intake box sat.
As for a ZE I have a 2.5" now and I will try a 3" later this year to see what the differences are, but I have a pretty good feeling that a 3" will work better.
PS, I have a straight neck ZE intake, JE50 MAF, and KL31 TB (stock ZE staight neck)

can u explain to me somehwat how lenght makes a dif?

Hoodzy wrote:can u explain to me somehwat how lenght makes a dif?

This link gives a fairly technical explanation but even disregarding the specifics of the math formula, you'll get the idea from reading the first four short paragraphs. http://www.engr.colostate.edu/~allan/fl ... age7f.html

PATDIESEL wrote:a longer pipe (up to a point0 will give more HP and a shorter (up to a point) will give more torque.

pretty much sure it's the other way around..short=hp and long=torque..
that's why the smaller displacement engines with big turbos has long runners on their intake runners to compensate the lack of torque on lower rpms. Same thing with our vris system (short at high rpms and long at low rpm)
I could be wrong though.

'A pressure wave is created when an intake or exhaust valve is opened. The wave propagates through the the fluid in the pipe at the speed of sound c. When this wave encounters a change in cross sectional area, such as the end of the pipe, a wave of opposite sign will be reflected from the end of the pipe.'

ok my question is, the intake valve would be the throttle body opening correct or w/e that is called, and the end of the pipe would be where the filter is, would the opening be the vaf? or would that be the end??

is it just huge mathematical question as to the distance from the TB to the VAF to the filter?? or does that make no differencE?

Ok, so 2.5"inch piping for the K8 and KLZE
I went to this site
http://www.convert-me.com/en/convert/length

To me, it seems like 2.5inch CAI piping is the right size for a KLZE and K8

Maybe this thread might go into the FAQs?