air horns for my 75 stinger

[mayflyIII]

howdy,

my dad (joe mccauley) has already extensively posted pictures of our allison and stinger, ill cut straight to the point ;)


i want to tune the stinger, and ive already made one air horn for the carbs. how many sizes up should i go with the high speed jets and is there some formula for calculating that, you know, taking into account the length of the air horn etc etc...

know i need to rich it up, and i understand the principle of it all, i just want to be careful and not have a nice little rattling sound of the rod clanking around in the crankcase.. ;)

http://i110.photobucket.com/albums/n83/Popeye011/220747_10150186887061952_620231951_6901138_295458_ o.jpg

http://i110.photobucket.com/albums/n83/Popeye011/219623_10150186912286952_620231951_6901523_3143434 _o.jpg

http://i110.photobucket.com/albums/n83/Popeye011/210655_10150186913051952_620231951_6901527_4832223 _o.jpg

http://i110.photobucket.com/albums/n83/Popeye011/209380_10150186912691952_620231951_6901526_2636645 _o.jpg

[Mark75H]

From what I understand about reed valved 2 strokes, reeds pretty well dampen out any significant intake tuning.

I don't know of any formulae or rule of thumb that gives any working results.

I suggest you try your set up and see for yourself.


What formula did you use to arrive at the length you produced?

[mayflyIII]

john calley told me about air horns and gave me the idea originally, he told me i can also put in grooves at the bottom of the horn to channel the air even more.

i just kind of eye balled it ( *grin) i started out with one and a half inches of material and down sized it some more. its got more than enough room under the calling, i checked.

i just looked on google for some pictures of air horns and used them as a model. then it was calipers and a small tolerance...

[mayflyIII]

true one doesnt have a lot of room for tuning, but the factory leaves sharp edges everywhere. smoothen them out and you have more power. you can also play with the reed boxes on an e tech and put a wall between every leaf, sort of make an enclosed triangle everywhere.

[Mark75H]

Bell or Jennings if you want some science on the length, but I think there is no way to guess what jetting will be needed if it works.

[mayflyIII]

I guess itll be one or two thousands bigger of jets and rich plugs

[Seagull 170]

You'll find quite a lot more intake science in The High-Performance Two-Stroke Engine by Dr. John C. Dixon. isbn 1 84425 045 8

As it was first published in 2005 it's a generation newer than Jennings & Bell it fits nicely between Jennings, Bell & Blair on the upward mathamatical path.

A very worthwhile third purchase.

[mayflyIII]

Ill look into that, im readig bell right now so thanks a lot! :)

[ima75man]

had carb stacks made for my 76-75 johnson,didn't see any gain, we went up two jet sizes. they looked cool,just wasn't legal for apba back in the day...didn't help on my 3-2 bbl, 56 inch omc. maybe i didn't spend enough time on set-up......the little blue bottle woke it up..

[Tim Kurcz]

Jim Kinsler designed velocity stacks installed on 1BBL OMC's eliminated reversion and smoothed transitions for my 45SS, 49.9 and 56.6's. Jetting did not change.

[mayflyIII]

Did you use rich plugs?

[wolfgang]

Jim Kinsler designed velocity stacks installed on 1BBL OMC's eliminated reversion and smoothed transitions for my 45SS, 49.9 and 56.6's. Jetting did not change.
confirmed for UIM SE. Slotting the cowling left and right of the carbs (not legal) and jetting up after milling the head makes power.

[Tim Kurcz]

Did you use rich plugs?

If you're talking spark plugs, there was no change. Either BR9HS or QL77JC4.

[Danny Pigott]

Mayfly, ask your dad he, knows about as much as anyone about this motor. I don't think they will help at all. If anything i would make them as short as possible just enough so you round the front of the carb. This is just my 2 cent. I have some info. about your boat i will post later i remember it when it was brand new.

[mayflyIII]

Mayfly, ask your dad he, knows about as much as anyone about this motor. I don't think they will help at all. If anything i would make them as short as possible just enough so you round the front of the carb. This is just my 2 cent. I have some info. about your boat i will post later i remember it when it was brand new.

he isnt to sure either :D

[Powerabout]

Has anyone looked at making them 3 different lengths to compensate for the 3 different lengths of the exhaust?
Merc 300 drag comes to mind

[LakeRacer99]

anyone selling these for 1bbl?

[sheuninck]

wanted to round the intake opening, got 1/2 mph ... no jet change

[OUTBOARDER]

Jim Kinsler designed velocity stacks installed on 1BBL OMC's eliminated reversion and smoothed transitions for my 45SS, 49.9 and 56.6's. Jetting did not change.

TSR SELLS TUNED LENGTH PROGRAM.
TUNED LENGTH IS CALCULATED FROM TIP OF REED TO END OF CARB.
THE PROGRAM SHOWS EFFECTIVE AND PEAK RPM.
GETTING TO CLOSE TO COWL OR SPRAY SHEILD CREATES A PROBLEM WITH REVERSION AT CERTAIN RPMS AND ALSO ALLOWS CARBS TO CROSS PULSE EACHOTHER. ON THE 45 WITH PIPE WENT UP 2 JET SIZES AND IMPROVED ACCELERATION EXITING TURNS.
THERE ARE SOME GUYS RUNNING 6 SEC QUATERS WITH KAWI 750 TRIPLE MOTOR BIKE AND THEY SWEAR BY TUNNING FOR 2ND PULSE ON THE INTAKE.

Also have seen same stacks keep hydro from getting on plane because of reversion and cross pulsing intake.

[Tim Kurcz]

anyone selling these for 1bbl?

Yes, I sell Kinsler designed turned aluminum velocity stacks $55 each includes fasteners plus shipping. They eliminate flat spots and spitback. PM if interested.

Tim

[Ballistic]

Also got these available for Yamaha 40/50 and 60/70 carbs

http://www.server-works.com/tiller.jpg

[Tim Kurcz]

Here's an image of current inventory.........

[wolfgang]

Also got these available for Yamaha 40/50 and 60/70 carbs

http://www.server-works.com/tiller.jpg

nice - they look exactly like the old Carniti ones. Made from plastic?

[Aeroliner]

When we were building the four carb Mercury 44 we looked for stack that would mount on the carbs that we were using. Doug Kay decided that he would turn a set and the photos below show them after mounting. We have done away with the mercury reed block and have 6 reeds per carb feeding streight through a the Polaris read towers. We run the engine regularly and it turns a ton of RPM without any issues.

Alan

[fs5]

When we were building the four carb Mercury 44 we looked for stack that would mount on the carbs that we were using. Doug Kay decided that he would turn a set and the photos below show them after mounting. We have done away with the mercury reed block and have 6 reeds per carb feeding streight through a the Polaris read towers. We run the engine regularly and it turns a ton of RPM without any issues.

Alan

that is one nice looking bit of gear!

[Aeroliner]

http://www.boatracingfacts.com/forums/showthread.php?t=6393&page=15

The 40-H thread above has all the photos of the engine build. You will have to work through it because info on a lot of other projects are covered along the way. Also there are some links to the first running of the engine up at Hillsdale MI in the thread. The Aeroliner web site also has some links.

http://www.aeroliner-boats.com

Alan

[mayflyIII]

@tim kurcz

those sharp edges and holes for the screws would make a big vortex disturbing the air flow....

[Tim Kurcz]

Sure, flow could be slightly improved with custom turned & spun stacks at 3X or 4X the price. That said, my Kinsler designed stacks helped win numerous nationals & high point championships, and at least one world record......