S/n: oc254550
I have a 1990 mariner 175 on a 1990 184 champion. Top speed is only 48-50mph. I have tried a few different props and results are pretty much the same. Did a cold compression check with throttle wide open and all cylinders are 90-92. Is that good for compression?
Compression gauges all read fairly different. It doesn't matter the reading as much as it does that they are all within 5-10% of one another. What do you mean you checked compression with the throttle wide open? You should easily be in the upper 50s-low 60's with that set up.Originally Posted by bwest0615
I checked compression with the kill switch pulled, and the throttle all the way forward. Motor was not at running temperature, I'm not sure if that makes a difference or not.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
I have tried three different props: a 25p solas, a 25p temptest plus, and a 21p quicksilver. I have noticed that the 21p washes out when I take off. So I know the prop isnt the most ideal, but the top speed is way low
I should be getting 60 easy. Will a prop make that big of a difference?
Yes, just remember that you don’t prop a boat out by mph, but rather what it tachs out at top speed. I’m not sure exactly what yours should tach at wot, but it should be around 5500-6000 rpm. That 21 will over tach. If your compression is good then I would go to the props forum and ask the pros what you should try. A 25 will be to much for that 150. I’d try a 23 tempest personally.
Last edited by Nate4Fishing; 05-09-2018 at 09:06 PM.
a good 23 TEMPEST what you need, set engine highth ,and roll on, rpm shold be right at 5900+- in cool weather, remember set up is everything, and every prop sets up different
.................................................. ...the scariest thing in life is the unknown ...................................
Check this FAQ topic for correct procedure - Compression Testing
Don was indicating this thread should be in the 2L, 2.4L, 2.5L forum (what OP's engine is).
_______
Phil
'09 Hewescraft ProV
'09 150 Optimax
Reply With Quote
