The OX66 EFI Yamaha should have built

[bigbluechevy454]

The motor is still running today.

300 hpdi with 250 ox66 electrics right?

[cali kid]

300 hpdi with 250 ox66 electrics right?

Yes sir. And fuel system.

[bigbluechevy454]

Where to u put the oxygen sensor? I don’t have a 250ox66 yet to like just gathering ideas first but planning on doing the conversion

[Capt.Insane-o]

Next month I'll be building a couple of these for a big boston whaler.. Waiting on a few more donor bits.

[bigbluechevy454]

Capt have u done this conversion?

[Capt.Insane-o]

First two. I've done the home work over the past few years and dealt with enough hpdis in the past. The customer did most of the leg work for the donor motors. He paid 600 bucks for two mostly complete ox66's and more than doubled his money back parting the lowers and trim systems out. It's pretty straightforward except a few injectors were bad and one cylinder head is chewed up.

[bigbluechevy454]

I’ve never seen a 0x66 stripped down. But where does the oxygen sensor go on the hpdi block?

[Capt.Insane-o]

Same spot. But the passages need to be machined.

[bigbluechevy454]

Ok that’s what I was wondering about. I figured it went it same place but noticed some fab was required

[Juanchy]

Hi guys, I have been thinking of doing something like this. What did you do with the direct injection lines? Did you just plug them? I am referring to the Oil injection of the hpdi

[rprinzo]

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!

where is this build section you speak of?

[cali kid]

I'm the OP. The motor is still running like the day I built it. You really need both the EFI and HPDI to do it. I used the EFI exhaust cover to mount the electronics, I also drilled and mounted the 3rd lift pump. I was able to mount the O2 by using files, a drill and 6mm tap. I used the HPDI heads. I was afraid the EFI heads, which will bolt up, would have too much compression. Very doable project if you have the donor motors.

[bigbluechevy454]

I’m doing mine as of today. Did u use the ox66 oil pump or the hpdi. It’s pumped differently in the hpdi

[Fishwhisper]

If you have a fully functioning 250 OX66, is there any benefit to moving the EFI and electrics to the 300 hpdi head? Any more power, reliability? Or is this more for someone who has a good 300 motor and just wants a more reliable motor than the HPDI offers?

[cali kid]

I’m doing mine as of today. Did u use the ox66 oil pump or the hpdi. It’s pumped differently in the hpdi

use the EFI oil pump and vst