120 vs 115

[tony120]

i was told by a marine mechanic that a 120 is a detuned 140. ok i understand the blocks and such. he said a 115 would walk away from my 120.on my boat!he said its 98 lbs lighter. and more fuel efficient...any ideas on loopers vs cross flow?

 

[Walker]

Re: 120 vs 115

I think your mechanic is on drugs. My 120 looper is stronger thru all rpm ranges than any 140 crossflow I've ever seen much less a 115.

 

[Dhadley]

Re: 120 vs 115

Thats backwards except for the weight deal. Any V4 looper will run cicles around a V4 crossflow. Literally. The 120 and 140 are the same powerhead and have insignificent differences in induction.<br /><br />Heres a direct comparison -- I had a 15' Allison we ran a V4 crossflow on. It turned 7200 and ran about 74 mph. 1/4 mile or top end. We switched to the V4 looper which turned 8200 and ran 82 mph in the quarter mile. Both powerheads (block, crank, rods, pistons) were stock (as produced). Both motors used the same gearcase and prop. Both used stock carbs. <br /><br />Good luck!

 

[walleyehed]

Re: 120 vs 115

I think Dhadley pretty well discribed the power differences in those engines, as they were developed for the 1985 requirement to meet prop-shaft HP ratings and were a totally new higher-cube design (120-140), and were 90degs, but loop charged

 

[tony120]

Re: 120 vs 115

thanks for shedding the light on that.as always, i have learned something new here.