turboz67

thanks guys i will start with 28"s

Bronco

Agreed, 28's are a good place to start. I wish I had some 1st hand experience with the 383's to help you but I dont (maybe labbed 30's). Please let us know the results as I am excited for you.

4mula,Phazar, you have it right. (nice boats by the way) As you know its all about how fast u can spin the props and be in the correct rpm range at WOT w/ minimal slip, based on your normal conditions.

Phazar, I am not quite sure I understand your question correctly, but I will try. I do not have smartcraft or any other way to truly measure the results from the motors (only lots of time on boats). I have done the math with gas consumption but that is hardly precise (every day=different conditions). I can only confidently tell you that the motors feel, sound, & run more efficiently. There is no laboring when I back off and reaccelerate (to not beat up my passengers going thru some rough stuff) and when in only 1 to 2 ft of chop the boat accelerates real fast and wants to keep going... It feels more like a finely tuned sports car (Labbed props) than a quick sedan (non labbed)... hope that helps.

turboz67

bronco,4mula and phazar, thank you very much for your insight on this project. i will start with the 28's . who do you guys know of that can relab the props.

4mulafastech

You're welcome turbo. As Bronco says, I'm excited for you too! Glad you made the decision to upgrade the 292. She is going to be a pleasure to drive with that power and new steering. If you can, it would be great to post some pics of this project. Do the Scorpion's come with header style exhaust?

Regarding labbing the props, I recommend contacting Brett at bblades (advertiser here - bblades.com). He was at Mercury for 12 years and the last 6 working with props. While I don't have any first hand experience with bblades, all the posts I have read have been very positive and he is an expert on the Bravo 4-blade props.

Good luck with the project! When do you think the swap will be complete?

Phazar454Mag

Thank you for the feedback, my question is related purely to cruising range / fuel economy when going on longer trips. I know they use a lot of fuel when playing around No problem. Just want to consider cruising range.

I am just thinking about cruising around 3200-3500 RPM, and I have heard that prop slip is often higher at mid RPMs using labbed props as opposed to stock props. I have a Northstar GPS with fuel sensors so I can see the difference it makes to get trim etc. right to reduce prop slip resulting in the best fuel economy.

But even though you don't have fuel sensors you can compare speeds at the same RPMs using the stock and labbed props, but may be you didn't notice a difference ?

Phazar454Mag

You are welcome

I do think you will be very happy and I am also very excited for you.

I wish I could hear the sound from those engines when running WOT at 6000 RPM

Phazar454Mag

I think the engines comes with 316L Stainless Steel CMI Headers, but correct me if I am wrong turbo ?

turboz67

they come with cmi exhaust. i am taking the boat out in two weeks. they are going to pull the motors and put them into the other formual. the plan then is to put the steering in and then the engines. i will only put the boat back in in the spring time. that gives me some time to pay for all of this thru the winter. hopefully the wifw won;t notice.

turboz67

i forgot to tell you guys. if you on you tube type in 383scorpion and there is a video of the motor running.

Bronco

You are welcome, and that video on youtube is awesome!

Phazar, the lakes where I live right now are not big enough collect any long cruise data (We are in a serious drought). when I first got the lab props I did actually compare speeds at different rpms with the 2 sets of props. The difference was negligible as some rpms were a mile or 2 faster and yet other rpms yielded a slower speed than with the regular props. Over all top speed was faster. Also with the labbed props, my starboard rpms are 200 to 300 lower than the port when getting on plane (out of the hole) but they even out once I hit about 30 mph and level out the boat. I believe that this is due to slight differences in the props as this does not occur with the regular props...

I think its fair to say that there can be more slip with labbed props than regular props. At the same time, that probably varies between different sets of "labbed props" . I highly doubt any 2 props would be truly identical and any pair is "perfectly" matched. I realize this info is hardly scientific but hope you find it helpful. Cheers.