Onex with 3300 jab engine

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Onex with 3300 jab engine

Postby JontyL » Thu Apr 30, 2015 6:01 am

Hi All

I am in the process of fitting a 3300 Jab engine to my Onex #142 and would like to discuss the engine position with some one who has done this.
I would like to discuss the cooling set up and the engine position relating to the carb / carb heat box.

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Re: Onex with 3300 jab engine

Postby Bryan Cotton » Thu Apr 30, 2015 10:06 am

Has anybody done this? Sounds like it will be a hot rod!
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX reserved
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dual sticks with sport trainer controls
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Re: Onex with 3300 jab engine

Postby Mike53 » Thu Apr 30, 2015 10:29 am

Bryan Cotton wrote:Has anybody done this? Sounds like it will be a hot rod!

Merle Reppert Onex #16 .You can find him in the completions gallery.
I know but one freedom, and that is the freedom of the mind.
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Re: Onex with 3300 jab engine

Postby gcm52 » Thu Apr 30, 2015 12:30 pm

I am just starting my Onex but am also looking at the Jab 3300 or possibly the Camit 3300. I emailed Merle and he said his Jab powered Onex cruised 145/150 mph at 2850 rpm and 6.5 gph and climbed at 1200-1500 fpm. He said his engine mount was made from 3/4 inch 4130---.035. He changed the outlet of the cowl and cut a little under the lip for prop bolt clearance.

I am thinking that since the weight of the Jab and the Aerovee are about the same that the mounting point in front of the firewall would be about the same. Since Merle used the supplied cowling the position of the engine must not have been too much different or he would have had to fabricate a new cowl.
George Mueller
Halfway through a Onex
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Re: Onex with 3300 jab engine

Postby JontyL » Sat May 16, 2015 1:43 pm

Hi George
Thanks for your help. The std jab carb sits 1" from the firewall if the prop hub is in the same position as the aerovee. Do you know if Merle used the aero injector or the jab carb with carb heat. Could you give me Merles email address I would like to get some more info from him. My email:

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Re: Onex with 3300 jab engine

Postby vhhomer » Tue May 30, 2017 11:24 pm

Have you finished and flown your Onex yet?

Recently I was fortunate to acquire Merle Reppert's Jabiru powered Onex. The aircraft only has 45 hours on it so there are some details still being sorted.

Where did you mount the oil cooler and how did you get air in and out of it? Merle used 2 1/2" SCAT duct from the cowl inlet to the oil cooler mounted on the left cowling side. Flying the aircraft back to Oregon on a 90+F day I had some problems with high oil temps and had to run at no more than 2650 rpm. I have since installed 3" SCEET duct and streamlined the duct intake. This has brought the oil temps down a bit. I also instruments the cowling with manometers and found the pressure drop across the engine to be 4 - 7 in H2O and a 1 1/2 - 2 1/2 in positive pressure in the bottom of the cowl. I suspect I could have a smaller cowl inlet and still have CHTs in range.
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