Hello,what is the main difference between the 35@ 2800 rpm vs the 38@ 3600 rpm's 800 additional turns for an extra 2.5 or 3 h.p. (I have seen it listed at 37.5 h.p.] seems like a lot for a little....? From the performance graphs it seems they make the same torque. I assume with the same bore and stroke the "extra" must come from fuel delivery? As I understand, these engines are designed to operate best at 80% of their rated maximum rpm's. What I am wondering is how either engine with the same transmission will be able to turn the prop most efficiently? I am repowering my Tayana 37 22k lbs. and have an 18x10 and another prop that came as a spare(or possibly was changed for size) 18x11 the engine I removed was a perkins 4108 with a velvet drive,not sure of the reduction. I am also not ruling out the 43. I have heard of 35,38,43 and 50's being installed in other boats like mine. Just trying to make a decision. A slower turning engine is more appealing for sure.I could get another propeller if neither of these are right. Any information would be helpful, Thanks, John
The Beta 35 and 38 engines are built on different versions of the Kubota V1505 base engine.
Forget the 37.5 HP version as that is an obsolete version built prior to the latest introduction of lean burn requirements by the EPA and their sister organisations in Europe, Japan etc.
The current versions are basically the same engine but the fuel cam (the one that drives the injection pump) has a different profile so the low speed version (35 HP at 2,800 RPM) get's a bit more fuel injected to increase torque at low speed. This version is possibly better suited to heavy boats with a propeller in an apeture. The high speed version (38 HP at 3,600) performs much the same but has a little more HP at higher engine speeds. There is an oil cooler fitted to the high speed version which accounts for the very small price difference between the two engines.
With a Tayana 37, if you are keeping your Velvet Drive and the ratio is 2.5:1, I suggest the Beta 38. If the transmission ratio is 2:1, then go with the Beta 35 or upgrade to the Beta 43. These options will ensure a decent propeller to drive the boat properly.
HI Stanley, Thanks for the info. I didn't keep the Velvet drive, although many have told me I should have and had it rebuilt.... I wanted to go with a new engine and gear and was able to sell the perkins complete. Most likely leaning towards the 43 at this point. The compactness of the 35/38 would be nice and although proven to push these boats,I am a fan of having the extra power. I may be seeking further info regarding the transmission selection. Thanks for the quick reply
