Sean Bowf
Well-Known Member
- Joined
- Sep 6, 2007
- Messages
- 716
Awhile back I had said that I had received a GO engine and would like to try it out. Well, I got some more time with it recently, and would like to pass on what I think I have figured out.
First off, the engine seemed to have high torque out of the box. It would pretty easily turn an X440 (not stock prop) that my CVRM would not turn. Problem I was having is that it would not turn it at a high RPM. Best speed I got from it with a stock MV hull was a little under 35 MPH. It would not turn my usual Y535 at high enough RPM to get close to this speed. The speed I got with the x440 kind of puts it on par with a stock AQ engine.
After taking the engine apart and measuring everything...I found that the bottom end looked better than the AQ engine, yet the head button had very small volume and had a high head clearance (.022) out of the box. It also had a high compression ratio (10.4 to 1). As a comparison, the CVRM has a stock ratio of 7.5 to 1. The high compression ratio would explain the high torque and low RPM.
I made a new head button for the engine, that lowered the head clearance to about .007 and the compression ratio to about 8.8 to 1. With everything else stock on the engine, I was now able to turn the Y535 with more RPM, yet it still turned the X440, but not as good as it used to. I did not have a lot of time to get a final tune on the boat/engine, but we pretty quickly got it to 36 MPH with the Y535. I think with a little more time with it we could have been at 37 or 38 MPH.
This is pretty good for a sub $100 engine, and is better than the stock AQ engine in the same hull. It is still a bit slower than the CVRM though (but a lot cheaper). Not sure what is a "real" GO engine and what is not, but they are on Ebay for $65 each.
I think if I lower the compression ratio a little bit more, I would be able to get more RPM out of the engine, and more speed. It does not seem to have too much of a problem turning the Y535 prop.
The throat of the carb is about 18% smaller than the CVRM. I think this may hinder its performance, but the CVRM and TZ have the same carb bore. With this in mind, I would think the GO would be able to get to where the CVRM is with it's stock carb and some more experimenting with the engine.
Sean
First off, the engine seemed to have high torque out of the box. It would pretty easily turn an X440 (not stock prop) that my CVRM would not turn. Problem I was having is that it would not turn it at a high RPM. Best speed I got from it with a stock MV hull was a little under 35 MPH. It would not turn my usual Y535 at high enough RPM to get close to this speed. The speed I got with the x440 kind of puts it on par with a stock AQ engine.
After taking the engine apart and measuring everything...I found that the bottom end looked better than the AQ engine, yet the head button had very small volume and had a high head clearance (.022) out of the box. It also had a high compression ratio (10.4 to 1). As a comparison, the CVRM has a stock ratio of 7.5 to 1. The high compression ratio would explain the high torque and low RPM.
I made a new head button for the engine, that lowered the head clearance to about .007 and the compression ratio to about 8.8 to 1. With everything else stock on the engine, I was now able to turn the Y535 with more RPM, yet it still turned the X440, but not as good as it used to. I did not have a lot of time to get a final tune on the boat/engine, but we pretty quickly got it to 36 MPH with the Y535. I think with a little more time with it we could have been at 37 or 38 MPH.
This is pretty good for a sub $100 engine, and is better than the stock AQ engine in the same hull. It is still a bit slower than the CVRM though (but a lot cheaper). Not sure what is a "real" GO engine and what is not, but they are on Ebay for $65 each.
I think if I lower the compression ratio a little bit more, I would be able to get more RPM out of the engine, and more speed. It does not seem to have too much of a problem turning the Y535 prop.
The throat of the carb is about 18% smaller than the CVRM. I think this may hinder its performance, but the CVRM and TZ have the same carb bore. With this in mind, I would think the GO would be able to get to where the CVRM is with it's stock carb and some more experimenting with the engine.
Sean
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