Running an HPDI at elevation.

Jeff C. · Post by **Jeff C.** » Sat Jul 25, 2009 10:25 am

Here's a question for you mechanics. Sometimes I take my Yamaha 175 hpdi from my current elevation of 1500 feet up to Union Valley reservoir which is at 4900 feet. When I do so, the motor is a bit more sluggish (I assume because the air is thinner) but besides that, is there any reason to be concerned, ie., could I be hurting my motor by running it at that high elevation without it being setup to do so?

Incidentally, for those who want to beat the heat (and the crowds) down here in the valley, Union Valley and Icehouse are great little lakes with plenty of smallmouth and very little pressure even on the weekends.

Jeff

BLAZER 210 · Post by **BLAZER 210** » Sun Jul 26, 2009 9:15 am

it wont hurt a thing but you will need to drop down in pitch to have a good hole shot and you will loose some speed.

201Pro · Post by **201Pro** » Sun Jul 26, 2009 10:33 am

BLAZER 210 wrote:it wont hurt a thing but you will need to drop down in pitch to have a good hole shot and you will loose some speed.

OK ... a follow up question is will there be much a difference in these outboards from going from the Delta to say 2,000 feet (Clearlake)?? Should we also drop a pitch when doing that too??

BLAZER 210 · Post by **BLAZER 210** » Sun Jul 26, 2009 4:16 pm

I usually run the same prop at clear lake as the delta but I loose about 2.5 to 3 mph

j10b · Post by **j10b** » Sun Jul 26, 2009 5:40 pm

You are also sluggish because to start will your fuel mixture is off. Get in some high speed runs to clean the plugs and you will see a difference.
I came here with a Bullet 20xd and a 225X, did the same thing. Clean the plugs and it ran 82 with my 27p. Same prop i was running at 166ft