Damien Walker 246 #1 Posted May 6 Does anyone know what the differences are between the 18hp (P218?) and the 20hp (P220?) Onans are please? It seems they are the same capacity. Presumably different carb/exhaust/cylinder head then? Share this post Link to post Share on other sites
RED-Z06 2,221 #2 Posted May 6 Same heads, block, 20hp had a 1 size large jetted carb, and a slightly more aggressive cam profile. Its not much, but having both, the 20hp is a stronger runner 1 Share this post Link to post Share on other sites
Damien Walker 246 #3 Posted May 6 5 hours ago, RED-Z06 said: Same heads, block, 20hp had a 1 size large jetted carb, and a slightly more aggressive cam profile. Its not much, but having both, the 20hp is a stronger runner Thank you for that, very interesting. My 518H has been fine so far but it sounds like a relatively easy mod to perform should you wish. The most difficult bit would be changing the decal on the bonnet of the tractor! Share this post Link to post Share on other sites
Streetrodchev 800 #4 Posted May 6 Yes as said above, the only difference in the P series 18 and 20 hp engines are the cam and the carb. All other parts are the same. 1 1 Share this post Link to post Share on other sites
Fordiesel69 263 #5 Posted May 6 Not to hijack this thread bout while on the topic of the onan P series, how about the 16HP? Share this post Link to post Share on other sites
RED-Z06 2,221 #6 Posted May 6 10 minutes ago, Fordiesel69 said: Not to hijack this thread bout while on the topic of the onan P series, how about the 16HP? Smaller displacement, same bore, .225" shorter stroke, same carb specs as the 18hp. The only P series that was a standout difference was the P224 1 Share this post Link to post Share on other sites
