OMC Tech 1975 85h.p. [Archive] - Scream And Fly Powerboat and High Performance Powerboating Discussion Forums

View Full Version : OMC Tech 1975 85h.p.

Aqua

11-08-2009, 10:49 PM

Is there anything that can be done to this engine to increase its performance without the risk of blowing it up? I've looked through the old threads but couldn't find any info on this engine(lots on 115 & 140).

flabum1017

11-08-2009, 11:39 PM

Not a whole lot without doing some port work, installing a 140 bubble back onto it and increasing the compression.

Aqua

11-08-2009, 11:50 PM

Would the 140 be a direct bolt-on? How would the 140 engine perform with the 85 exhaust and lower end gears?

EMDSAPMGR

11-09-2009, 07:13 AM

The 85 (and later 100 hp engines) were a smaller powerhead than the 115/135. They were only 92.6 cubic inches and share little in common with the 115/135 at 99 cubic inches. A 135 from that same vintage would bolt right on your midsection. You should be OK with any powerhead up through 1976.