[Barry Built]

I have L90 Canisters that were previously installed on my QQ120". The last engine was a 3W 170. I am now running a DA170 in the same plane. I have to cust about 3" off of one header and about 2" off the other header.

How will this perform with the DA170?

I am inclosing pics.

[Barry Built]

If I get pro flows I will have to re do canister mounts. I don't want to do that.

[yakken]

I would think that you want to keep the header length the same.

[BVargas]

Originally Posted by Barry Built

If I get pro flows I will have to re do canister mounts. I don't want to do that.

Yes you will have to use a smaller dia. mount because LARGE proflows are only 3" dia. and 10 1/2 " long. L90K's are 3.25" dia and 14 1/2" long.

Proflow recommends approx 10" header length for starters for a da.

Header lengths need to be the same.

The stock header length for a 3W-170 on front dump proflows seems to be ok for me


BV

[Buttface]

I'm interested to know how smooth the throttle transition is with the L90s . I have considered that option but am torn between them and the MTW 115ks .

[Mithrandir]

Originally Posted by yakken

I would think that you want to keep the header length the same.

Not necessarily...

the Front Jug gets about 10 degrees hotter.. (Delta T = 10).. and that is the longer header..
considering the RPM range is between about 1200 to 6000 (6000-1200 = 4800 rpms or 80 rps) and the speed of sound in the 800'ish degree exhaust gas is approximately 250 m/s.. and include a Density-Altitude adjusted Reynolds number Coefficient of 1EE-2....when you do the math you get a delta header length = 80 rps * 250 m/s *(1/800 c) * (1 EE -2 RnC) / (10 Delta T) you get + .025 meters...

or approximately ..

+ One Inch

[Bunky f. knuckle]

You lost me after 10 degrees hotter...........

Hell, someone on the other site said to balance cylinder temps, you lower the compression on the cylinder that is hottest.

[Votec Yak Guy]

Mith.....formula is missing a coefficient of ballistic synchronicity....correcting for this results in a header length differential of .31456745 inches.

Clear now?

[Votec Yak Guy]

Barry, I run L90's on my 3dub 157's and 170's with the same header lengths.....no issues

[Barry Built]

Originally Posted by votec yak guy

mith.....formula is missing a coefficient of ballistic synchronicity....correcting for this results in a header length differential of .31456745 inches.

Clear now?

chrystal!