Viscount
Well-Known Member
I have 130hp AD31s; I notice that some of these engines are claimed to produce 150hp. Is it possible to modify the 130hp unit to produce 150hp? Thanks for any tips.
AD31 130hp to 150hp
- Thread starter Viscount
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Sneds
Well-Known Member
I to have twin AD31Ps allways thought they were 150HP each maybe the clue is in the letter? ie P
Very economical, around 30-35 LPH (both) at around 24 kts
Very economical, around 30-35 LPH (both) at around 24 kts
AdeOlly
Well-Known Member
The AD31 was made in a number of variants over the years, at 130 and 150hp outputs. If you go clicky here and search on just AD31 they're all listed.
As to whether you can uprate I don't know.....
As to whether you can uprate I don't know.....
Chris_d
Well-Known Member
I've got the AD31P's which are 150hp, they rev to 4000/4100rpm, which seems to be where the extra power is, i'e all in the last extra 300rpm over a 130hp version.
A fellow forumite on here has an identical boat to me with the 130's but seems to get virtualy identical performance and fuel consumption, maybe mine does 1 or 2 knts more at the top end. However we both suffer from lack of power in any kind of swell where we get knocked off the plane, so mid range power and torque seem to be identical, which is where you want the extra power. 3500rpm seems to be the best cruisng speed in both boats giving 22-24knts.
I guess to uprate you would need a new injection pump and injectors minimum, but not sure it would be worth the cost. Might be better in your lighter Sealine however.
A fellow forumite on here has an identical boat to me with the 130's but seems to get virtualy identical performance and fuel consumption, maybe mine does 1 or 2 knts more at the top end. However we both suffer from lack of power in any kind of swell where we get knocked off the plane, so mid range power and torque seem to be identical, which is where you want the extra power. 3500rpm seems to be the best cruisng speed in both boats giving 22-24knts.
I guess to uprate you would need a new injection pump and injectors minimum, but not sure it would be worth the cost. Might be better in your lighter Sealine however.
AdeOlly
Well-Known Member
Agree that 3500-3700 is the sweet spot for cruising which gives us 22-25 knots and ~2.2mpg, but we don't suffer with being knocked of the plane unless the sea is really quite bad.
Viscount
Well-Known Member
Thanks for the replies; it sounds as though it's not going to be worth the effort and cost even if it is possible at all. I've seen 26kts in ideal conditions flat out but usually cruise about 21kts, less if it's in any way lumpy. I get between 2 and 2.5nmpg depending on speed and hull fouling.
