The OX66 EFI Yamaha should have built

**cali kid** · 03-09-2015, 12:45 PM

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Can anybody guess what this is? Turned out to be a pretty neat project.

**ChrisCarsonMarine** · 03-10-2015, 08:33 AM

3.3.....

**dnelson964** · 03-10-2015, 09:20 AM

HPDI 3.3 block with OX66 conversion ?

How much more power do you think ? Is compression bumped any ? Can it run higher RPM as set-up here ?

I like it..

**cali kid** · 03-10-2015, 11:06 AM

You got it . Its a 3.3. 250-300 hpdi powerhead. Used the bigger 6 petal hpdi reed assy.,hpdi starter and flywheel. Operating system is off 250 efi. Ran great right out of the box. It's on a wide 25 Parker. Got over 200 hrs.on it. Torque Monster. Real smooth and quiet. Owner says its more economical than the 250 efi was.

**cali kid** · 03-06-2019, 11:38 AM

I'm bumping this for the pics.

**FORBESAUTO** · 03-06-2019, 06:52 PM

I like it! What did you plug the injector holes with? Now it I can just get a EFI setup

**Dave S** · 03-07-2019, 12:29 AM

when gunners.... hot rodrees... get the new/old stuff.....when $$ infn there price range.... funnnn happens. Gunnners.... aka... old ...243.....hot one.....222 ya......270.... they were all out of the box....in there time....wildcat.... cartges....Just Dave.......

**cali kid** · 03-07-2019, 08:58 AM

Originally Posted by FORBESAUTO

I like it! What did you plug the injector holes with? Now it I can just get a EFI setup

3/8 tap, short allen screw, brass washer, locktite. Just find a blown 250 ox66. Plenty around.

**madmatic** · 03-07-2019, 10:39 AM

may i ask why you decided to remove the direct injection and go with 0x66 efi? also do this mean you are able to run premix and lose the oil injection?

**cali kid** · 03-07-2019, 11:19 AM

Originally Posted by madmatic

may i ask why you decided to remove the direct injection and go with 0x66 efi? also do this mean you are able to run premix and lose the oil injection?

Main reason the 3.3 liter HPDI is a very fragile animal. I put 7 powerheads on one motor all paid for by Yamaha. Factory reps were involved. Finally Yamaha bought the motor back and gave the customer a deep discount on a four stroke. Changed many more over the years, some only lasted 30 or so hours. Had a bunch of powerheads laying around and did it for the fun. All junk parts, almost no money. I like the big forged pistons, and the heavy duty block as well as the extra 200 cc's. The efi version is a real powerhouse, super reliable, over a thousand hours so far, and I left everything stock. Would really respond to some tunes. You could premix, but Yamaha oil injection is very reliable.

**Capt.Insane-o** · 03-07-2019, 12:21 PM

Id love to build a couple of these

**madmatic** · 03-07-2019, 01:36 PM

very cool! i have a hpdi 300 sitting in my back yard i was thinking of building with the hydrotec phase 3 kit and mounting it in a VW bug, if you could do a build thread on this in the build section i would greatly appreciate it!