Tuned Pipe Header Length and Prop Choice

[Notorious B.E.N.]

I'm making some progress on my Dalton 300 and still thinking about what engine/exhaust to run. I'm probably going to go with a DA 150L or GP 176 EVO on stock mufflers but I still have an interest in cans and tuned pipe set ups.

I was looking at some information on different props and found different recommended header lengths. It makes sense so has anyone else found this?

For the Dalton 300, I plan on mostly Sport/3D but since Abilene may start holding IMAC contests again and I may be able to make some of the Fort Worth contests, I could be switching props occasionally through the year. Basically 2 blade for typical flying days and possibly a 3 bladed prop for windier days.

 

[jamesrxx951]

I have a GP176 EVO on the plane bender smooth pipes. Right now I only have less than a gallon burned through the engine and it is an animal. The only prop I have flown with is a Mej 29/12 3B and it spins it at 6500 RPM on the ground after a 15 minute flight. I believe the Mej 30/13 was in the same rpm within a 100 on the ground. I purchased a Falcon 30/12-3B to try out as I think it will load up the engine a little better. Keep RPM down and thrust higher at lower RPM for IMAC. I have to say smoothness on the GP is similar to my old DA150 I had years ago. Power wise the GP is stronger than a DA170. Im running the longer recommended header length on my tuned pipes. I think it is 13".

 

[Kevin-Young]

to be honest it really depends on the exhaust brands that you are looking at. For example our JTEC HP-90 tuned pipes do not have the peaky transition that the RE'3, 1090's or greeves have so you will have a much more linear throttle response. Canisters in general will not have the peakiness of those tuned pipes because really a canister is a high volume muffler and not really tuned. Prop recommendations are also dependent on the exhaust you choose. If you decide to go tuned pipes you may look at some different props due to the increased rpm that you are going to get out of the engine.

All my experience is with the DA's and I certainly am going to recommend going with the 150L because it is a great running engine. If it were our tuned pipes or canisters they are designed to work with the stock header length that you get from DA and for sport flying I would probably go with a 30x12 or 32x10 mejzlik. The falcon props are really nice as well, I just have not run them on the 150L so I can't recommend which size is right for that type of flying.

 

[Capt.Roll]

Are there any "general" rules to follow when selecting an exhaust can/pipe/header for a given engine/prop? Say engines in the 100cc to 200 cc range. Is there anything published as a guide that shows weight gain/loss, performance gains, noise gain/loss, etc?

As an example, I currently have the GP supplied exhaust mounted on my GP123. I'm thinking I'd like to go with some headers/cans here in the near future. Not looking for brand recommendations but if a set of cans are used that fit the 100-120cc class of engine, same for the headers, same for the prop; how is the best way to determine header length other than trial and error?

 

[Notorious B.E.N.]

to be honest it really depends on the exhaust brands that you are looking at. For example our JTEC HP-90 tuned pipes do not have the peaky transition that the RE'3, 1090's or greeves have so you will have a much more linear throttle response. Canisters in general will not have the peakiness of those tuned pipes because really a canister is a high volume muffler and not really tuned. Prop recommendations are also dependent on the exhaust you choose. If you decide to go tuned pipes you may look at some different props due to the increased rpm that you are going to get out of the engine.

All my experience is with the DA's and I certainly am going to recommend going with the 150L because it is a great running engine. If it were our tuned pipes or canisters they are designed to work with the stock header length that you get from DA and for sport flying I would probably go with a 30x12 or 32x10 mejzlik. The falcon props are really nice as well, I just have not run them on the 150L so I can't recommend which size is right for that type of flying.

If I went with the 150L, I would seriously consider doing tuned pipes. The props I was thinking of running on it would Mejzlik or Falcon and 31x12 or 32x10 for a 2 blade or 28.5x12 or 29x12 for a 3 blade.

 

[jamesrxx951]

If you go with a DA150, my personal choice would to not use the 29/12 3B or 31/12 2B. I used both on my 170 on RE3s and the 29/12 seemed to not have good performance from load so I suspect the 150 would be weaker. I did like the 31/12 on my old 150 and re3 combo and in cooler weather the performance was good but in hot weather it was to much. I did like that prop on my old 170 though.

As a side note I have found Falcon props to load the engine more than Mej.

A 30/12 2B was my favorite prop on a DA150 on pipes. I have not tried a 28.5X12X3 though.

 

[Bunky.F.Knuckle]

30x12 2B You could try the 31x12 2B. I'd love to try one on my 3W 150 and 157.
28.5x123B

 

[orthobird]

anyone know the header length for DA 150 on KS 1090 pipes?