Exhaust throttle

[Kez]

I used to have an exhaust throttle made by Steve Muck (if memory serves) and another by Prather for the K&B's in the late 80's. I don't see them anymore. Are they still being made?

Thanks,

Kez

 

[MarkScott]

Kez,

Believe you are looking for inboard ET's? Prather may still make them. Those and other brands can be found on fleebay every now and then. Think I've got one or two for the 7.5 IB's.. Then again, I have 2 - 3.5 and 2 7.5 Gardner XXL's for my OB's.

Mark..

 

[not2bright]

i have one for a ops .65

 

[Scott Schneider]

exhaust throttles went the way of the doh doh bird

Once RPM started making killer carbs, then Aeromarine, and others with low needles the Ex throttles were no more. heat and vibration was so rough on them, leaking and the mess a real P.I.T.A.

Yes they work GREAT ! once you adjust fuel tank level right so engine can idle. but in the current engines that use HUGE carb intakes sizes and are super fuel thirsty, I doubt you would have much luck.

I have not run one now in @ 8 to 10 years. And would not even if they were avalible still.

B) Scott

 

[TimD]

The real benefit to running an exhaust throttle isn't the throttle itself - it is being able to replace the carb with a venturi. Tuning the shape and length of the venturi has a big effect on performance. A venturi can be a lot better for power than a carb if it is done correctly.

Several people in my club are using them on the current CMB range of engines up to the 1 cube without problems as long as the venturi is done correctly.

Shame the E/T's are so messy.....

Gary Holborow at Oz Engines is making E/T's now. They look good so far

 

[gil sonsino]

I have one made from International's for a OS 46 that I used on a SKDaddle 40 in the late 70's but would suggest to forget the use of it! No low or medium range and lot of mangled plugs.

Gill

 

[Don Templeton]

Couldn't agree with you more Tim. With the correct venturi, the acceleration is just plain awesome! Works very well on starts and in rough water conditions when you have to time your moves just right.

Don

 

[Pennywizz6]

They should make a servo that closes the main pipe and lead it through a other pipe under the hull like the silent choice on full size boats with through hull, that would be sweet On that topic why dont they have the exhaust go in the water? On full size boats the performance gain with through hull is very little, it just sounds way cool! It would be great for people that arent race oriented and dont like the loud noice of an rc engine.

Phil :blink:

 

[Don Templeton]

Pennywizz6:

What the #*#@x are you talking about and what does that that have to do with exhaust throttles? :blink:

Don

 

[Pennywizz6]

Lol sorry Don, I think im in my own little world with this one.

Phil :blink: :huh:

 

[Kez]

Thanks all for your replies.

I still have two NIB K&B 3.5 with the butterfly exhaust throttle that I want to use in my new project. Because the front housing is rotated 90 degrees, it is not easy to mount a carb. Back in the 80's, it was popular to replace the can muffler with an exhaust throttle and tuned pipe.

Back then, I had actually swapped the front end with a car enginer (8801), turned the case 180 degree and ended up with a pretty strong running engine.

The only problem with exhaust throttle, in my opinion, is that it is not fail-safe. By that I mean if the bolts vibrate loose, you will end up with a screaming engine and have no way to shut it down until the boat flip or run out of fuel.....ask me how I know ;-)

Regards,

Kez

 

[Don Templeton]

Pennywizz6:

No problem, I just couldn't figure out where you were going with a servo that closes the pipe and leads to another pipe etc, etc. :lol: :lol:

Kez:

I have a barrel exhaust throttle on a K&B 3.5 of that era. The engine is probably trash but you are welcome to have the whole thing if you want it. It came out of an old crapshooter made for an SAW run by Marty Davis and the engine prepared by John Ackerman. I would guess the time frame would be about 1980.

Just E-mail me and let me know.

Don