i beg to differ, my cammed 4k made bucketloads of torque down low, i couldn't have wanted more, i could however have used more top end

Hehehehehe thats funny you can never have too much low end torque out of a 1300,try shortening the extractors for more top end how long are they at the moment?

I haven't googled or read this stuff for a while, so some of the detail may be a little fluffy ... but this is how I understand it:

 

Extractors are tuned to provide best performance around a specific rev range.

Length between "refelection points" is what's critical ... in particular, the length from the exhaust valve to the first "pipe join" - ie. the length of the primaries.

The shorter the primaries, the higher the rev-range the extractors work best at.

 

A performance boost at low-mid revs works well in lots of places ... motorkhana, the street, rallying, the street ... the street. To get this, you need reasonably long primaries.

 

Problem: there is only so much space in an engine bay and under a car ... it can be hard to make the primaries as long as you'd like, and still have room for them to fit.

 

Compromise: rather than make the primaries as long as you'd like, make them shorter (1/2 the desired length would seem to make sense from a harmonics perspective) and add a second pipe join (reflection point) at the desired primary position. Join the primaries with another such that both exhaust ports are not open at once. What you get is an effectively longer primary with only 1/2 the pipes needing to be accomodated (at the end).

 

So - in general: 4-1 are usually tuned for high rev-ranges and 4-2-1 are tuned for lower (mid-range) revs.

 

My 4K rarely gets to 7k (horrible noises indicating valve float/bounce happen there!), so I use 4-2-1 extractors.

 

chairs,

Slapper

i totally agree blown 5k

 

If you have a mild cam and its for the road any decent set of extractors will be fine.

 

i run 4 into 1s in my car. more to do with being the right price at the right time then anything else. ideally i would have gone 4-2-1s at the time, the extra midrange would have been nice with the previous K, 3K, and 4K.

 

i have a set of 4-2-1s to play with, but couldn't be bothered changing them over. i don't think they would be so much of a benefit now with the current 5k.

 

jamie, you can never have enough torque. my ke15 with warm 5k goes up the toowoomba range in 5th, the ke16 with (admittedly sad) stock ke70 4k with 4-2-1s needs 3rd.

Edited July 15, 200521 yr by Felix

4-2-1s are easier to work with...in a ke1x anyway. the 4into1 collectors are a bit large.

i wouldn't trade the top end for the torque tho, but that's just me

i have never paid for any of my K motor extractors, and i've owned a few now :)

hey!....i own a set of the top ones in that picture too.... :)

I like torque. Torque is a GOOD thing.

you need a GZE then fook.

Turbo diesel?

carn, don't soft it. blown big block :)

ONLY one blower?

 

that thing has four V8s as well. doug wins! :)

Back to the subject. The 7k we just got has

4 to 1 and i don't think our torque suffers.

Craig sheared the tailshft nuts at low revs

Thats enough torque for me. :)

Yeah but they`ve got a big stroke and some swept volume in relation to 4ks,i can't say i`ve sheared off any tailshaft nuts/bolts with my supercharged 5k mind you i never really launch it hard in first it just spins up.

it all depends on the motor mods, compression, intake,etc i have 4-2-1 mandrel bent genies on a 5k in a ke 55 i have no complaints on them for a good street engine stick with the 4-2-1s give good bottom to mid range power without sacrificing to much top end power another benifit is pulse tuning where the exhaust gases are seperated from the other cylinders causing less turbulance as the gases flow they go 4-2-1 instead of 4 into 1. more flow + less back pressure = more power