Quick test for Chrysler Twins
Posted: Sat Aug 23, 2014 9:40 pm
Fastjeff wrote the following:
Re: Chrysler engine specs/timing
Lots of things make for a lack of WOT rpm: engine tune, boat hull condition, props (pitch and condition), overloading, etc. That said, if your boat does NOT labor getting on plane, or holding a plane, then I wouldn't be so concerned about that 3,400/ 3,600 max rpms. (Mine makes about 3,900 tops.)
Have you tried the Fastjeff Dyno Test? To wit:
1. Set boat on plane at a comfortable cruising rpm (say, 2,500 for this case)
2. Set both engines close to 2,500
3. Open the port throttle all the way, wait until the rpms top out, and record the number
4. Return to the 2,500 cruise rpm, then repeat the above for the other engine.
If one engine tachs out much lower than the other you have a problem there. It could be the engine itself or a bad prop--you'll have to determine this.
Jeff
Thanks Jeff
bill
Re: Chrysler engine specs/timing
Lots of things make for a lack of WOT rpm: engine tune, boat hull condition, props (pitch and condition), overloading, etc. That said, if your boat does NOT labor getting on plane, or holding a plane, then I wouldn't be so concerned about that 3,400/ 3,600 max rpms. (Mine makes about 3,900 tops.)
Have you tried the Fastjeff Dyno Test? To wit:
1. Set boat on plane at a comfortable cruising rpm (say, 2,500 for this case)
2. Set both engines close to 2,500
3. Open the port throttle all the way, wait until the rpms top out, and record the number
4. Return to the 2,500 cruise rpm, then repeat the above for the other engine.
If one engine tachs out much lower than the other you have a problem there. It could be the engine itself or a bad prop--you'll have to determine this.
Jeff
Thanks Jeff
bill