JPI Engine data

[Michael Rath]

I just installed a new JPI 730 and I love all the new data that I am getting. I have to say it is one of the best upgrades that I have ever done!!

Just for reference I have a 250 with the O-540 and a Lopresti cowl. I have to say that I am a little disappointed with my CHT splits. I know that I will never be as tight on my spreads as my injected brothers but I am seeing up to a 70 degree difference of CHT's in cruise. That makes my gami spread a little to large when I lean it out.

I also need to adjust the K factor for the fuel flow, I am currently reading a little high. I am just curious if any other members with the 0-540 have data they could share. I would like to see if I'm in the ball park with my 0-540.

MR

[Andrew Foster]

That would seem about on par with our 0-540.EGT spread is usally between 150 or so in cruise power, wot, leaned to 50 rich of peak. Obviously at 75% power or less. 61 250, stock cowl.

[Michael Rath]

Thanks Andrew! If anyone else has data I would love to see it.

[MULEFLY]

My single had the IO-540... and I had the JPI... biggest thing to bring the CHTs closer is baffles... quoting another sage that posts here from time to time..."tighter than a frog's butt". Holes that are cumulative to the equivalent size of a quarter can be a problem... it must be a passion and it is not an easy journey.

[Zach Grant L1011jock]

CHT spread is all baffle work, EGT spread on a carb engine is...well what it is...unless you get fanatical with flow matching cyl, polishing all of the turbulance inducing induction items etc. I think you are in the ballpark. You will notice that running Wide Open Throttle will make things a little more balanced vs partial throttle settings. You get better efficiency as you can lean tighter without one going lean way before the others and shaking the plane. Also check your intake gaskets and junction hoses. They are cheap and easy to replace and are often neglected.

-Zach

[Michael Rath]

Intake gaskets and junction hoses are on my list for the next annual. My baffling looks really good but I'm sure I can get some more improvement. My number six runs very cool and I think it might be due to having the big lopresti cowl door right below it. Not sure how a guy could account for that? I will keep working on it!

MR

[Kevin Ebsen]

[Michael Rath]

Kevin,

That's great. I wish my readings were that steady! Thanks for posting your data!