Labbed vs going down a size...

[HavaToon]

When I got my absolute best numbers was 3 trips ago. I had 1/8 tank on each side and just my dad and I. I hit 4800 rpm and the speedo was hitting 72-73. With gas and and another person I still get 4800 rpm but only hit 70 on speedo. 80 degrees average temp. Water was glass but when I got a lil chop is when it ran fastest

V - if that's what you are currently getting for speed based on GPS, you're doing great! Labbing your 24 will only net you 150-200rpm and like mentioned 1-2mph. If you are for sure planning on doing the ECM upgrade or any other power adder I wouldn't do any prop modification at this time as you will need to do it again after adding the power (likely a 26p). I'd say save the money for the power upgrade(s) and leave your 24 alone.

 

[BHC Vic]

V - if that's what you are currently getting for speed based on GPS, you're doing great! Labbing your 24 will only net you 150-200rpm and like mentioned 1-2mph. If you are for sure planning on doing the ECM upgrade or any other power adder I wouldn't do any prop modification at this time as you will need to do it again after adding the power (likely a 26p). I'd say save the money for the power upgrade(s) and leave your 24 alone.

That's a great point. Not to mention the tune and new prop are actually
Not too far apart in price. After the tune I will have to run 91 though

 

[BHC Vic]

I would like to have a little collection of props but I was unaware they cost so much. I want to say it was a whole lot cheaper replacing the prop on the bayliner [emoji4]

 

[Singleton]

That's a great point. Not to mention the tune and new prop are actually
Not too far apart in price. After the tune I will have to run 91 though

Once you do the tune and headers let me know. My collection of props can be used to test.

I have the following
- 26 Mercury Stock Bravo 1
- 26 Mercury Labbed Bravo 1
- 26 BBlades tuned for top end
- 25 Cutting Edge 5 blade tuned for mid range
- 27 Cutting Edge 4 blade tuned or top end

 

[HavaToon]

Once you do the tune and headers let me know. My collection of props can be used to test.

I have the following
- 26 Mercury Stock Bravo 1
- 26 Mercury Labbed Bravo 1
- 26 BBlades tuned for top end
- 25 Cutting Edge 5 blade tuned for mid range
- 27 Cutting Edge 4 blade tuned or top end

Nice collection!

 

[BHC Vic]

Once you do the tune and headers let me know. My collection of props can be used to test.

I have the following
- 26 Mercury Stock Bravo 1
- 26 Mercury Labbed Bravo 1
- 26 BBlades tuned for top end
- 25 Cutting Edge 5 blade tuned for mid range
- 27 Cutting Edge 4 blade tuned or top end

I'm not sure I'll do the headers that still makes me nervous

 

[HavaToon]

Just swap the engine for this 520. [emoji106]

http://www.riverdavesplace.com/forums/showthread.php?t=126933

 

[CobraDave]

Just an update on my prop deal. I decided to contact Cutting Edge Propellers in Santa Ana and told them I just wanted a better hole shot and the prop seemed to slip a bit much when taking off. Spoke to Augustine who stated if I lab it it would give me about 200 RPM on the top end and greatly improve the hole shot.

He told me it would take three days. I said I was driving from Fontana so he said just drop it off and come back in to hours ( on a Saturday). Well just had it done. I'm anxious to test it out.



Augustine told me the tips of a couple blades looked slightly bent and said that could be some of my problem. Had it fixed up and looks like he just sharpened one end of each blade.

 

[BHC Vic]

Just an update on my prop deal. I decided to contact Cutting Edge Propellers in Santa Ana and told them I just wanted a better hole shot and the prop seemed to slip a bit much when taking off. Spoke to Augustine who stated if I lab it it would give me about 200 RPM on the top end and greatly improve the hole shot.

He told me it would take three days. I said I was driving from Fontana so he said just drop it off and come back in to hours ( on a Saturday). Well just had it done. I'm anxious to test it out.

View attachment 430574 View attachment 430575 View attachment 430576 View attachment 430577

Augustine told me the tips of a couple blades looked slightly bent and said that could be some of my problem. Had it fixed up and looks like he just sharpened one end of each blade.

What was the price maybe this would b something worth doing

 

[CobraDave]

What was the price maybe this would b something worth doing

175

 

[djunkie]

I'm working with Augustine as well on a prop for my boat. He's been great. I highly recommend him.

 

[BMABITY]

I just talked with CE today, Augistine told me the same as you, lab my 26 B1 for a better hole shot.

I have a 28 Magic with 525/XR combo and want better plaining, top end isnt a big concern. Everyone tells me to stsy away from 5 blades due to stress on drive. Im going to try my friends 23 B1 this weekend in havasu, but i think it will be too small. Trying to get my hands on a 24 for testing but Augistine told me to just lab my 26 and i would notice a huge difference on plaining while keeping my mid and top the same.

When do you plan on testing your prop, im very intrested in your results.

 

[NicPaus]

I just talked with CE today, Augistine told me the same as you, lab my 26 B1 for a better hole shot.

I have a 28 Magic with 525/XR combo and want better plaining, top end isnt a big concern. Everyone tells me to stsy away from 5 blades due to stress on drive. Im going to try my friends 23 B1 this weekend in havasu, but i think it will be too small. Trying to get my hands on a 24 for testing but Augistine told me to just lab my 26 and i would notice a huge difference on plaining while keeping my mid and top the same.

When do you plan on testing your prop, im very intrested in your results.

The labbed 26 I have is a big difference from the stock 26 I have. I can feel the difference in weight while holding the 2. Most likely have the stock 26 labbed as well. The 23 will give you a lot better hole shot might work well with a full load and this heat. Be good for tubing.

 

[BMABITY]

The labbed 26 I have is a big difference from the stock 26 I have. I can feel the difference in weight while holding the 2. Most likely have the stock 26 labbed as well. The 23 will give you a lot better hole shot might work well with a full load and this heat. Be good for tubing.

It just seems to me, for what I'm after, a smaller diameter and smaller pitch 5 blade would work best but what the heck do I know. I don't like the idea of thinner blades, considering my boat is always loaded heavy, so hopefully that isn't a huge problem but I'm concerned about blade flex.

Did you have the diffuser trimmed or removed during the lab process?

 

[LargeOrangeFont]

Just an update on my prop deal. I decided to contact Cutting Edge Propellers in Santa Ana and told them I just wanted a better hole shot and the prop seemed to slip a bit much when taking off. Spoke to Augustine who stated if I lab it it would give me about 200 RPM on the top end and greatly improve the hole shot.

He told me it would take three days. I said I was driving from Fontana so he said just drop it off and come back in to hours ( on a Saturday). Well just had it done. I'm anxious to test it out.

View attachment 430574 View attachment 430575 View attachment 430576 View attachment 430577

Augustine told me the tips of a couple blades looked slightly bent and said that could be some of my problem. Had it fixed up and looks like he just sharpened one end of each blade.

Any update on how this prop worked out for you? I have a spare prop and thinking of trying a labbed one. I have the same boat - Cobra Razor 230, but with the 6.2MX. I run a stock Bravo 1 22P prop now. The boat runs about 59-60 MPH (via GPS) full of fuel (and beer) with 2 people at 5400 RPM. I can probably eek another MPH or 2 out of it with low fuel and cooler conditions. It sounds like I need a 23 or 24 pitch labbed prop because if I lab what I have I'll be on the rev limiter.

I plan on getting a tune for the boat at a minimum in the off season. The Whipple tune raises the rev limiter to 5600, but I don't really want to spin it that high if I can avoid it.

I may do headers as well but seeing how expensive they are its probably just better to throw a Whipple on it and call it done.

 

[CobraDave]

Any update on how this prop worked out for you? I have a spare prop and thinking of trying a labbed one. I have the same boat - Cobra Razor 230, but with the 6.2MX. I run a stock Bravo 1 22P prop now. The boat runs about 59-60 MPH (via GPS) full of fuel (and beer) with 2 people at 5400 RPM. I can probably eek another MPH or 2 out of it with low fuel and cooler conditions. It sounds like I need a 23 or 24 pitch labbed prop because if I lab what I have I'll be on the rev limiter.

I plan on getting a tune for the boat at a minimum in the off season. The Whipple tune raises the rev limiter to 5600, but I don't really want to spin it that high if I can avoid it.

I may do headers as well but seeing how expensive they are its probably just better to throw a Whipple on it and call it done.

No i will go out in two weeks. Stock I was at about 4700-4800 Rpms WOT loaded. Sounds like you could go up a pitch

 

[LargeOrangeFont]

Yea my friend has a bravo 24 on his boat, maybe I need to swap him and see how it runs.

 

[LargeOrangeFont]

No i will go out in two weeks. Stock I was at about 4700-4800 Rpms WOT loaded. Sounds like you could go up a pitch

One quick question - is the labbed prop sharp enough to cut you? I just dont want my wife or kid to fillet their foot of they accidently bump into it.

 

[2FORCEFULL]

I've done a ton of prop testing lately and here's my take.

1. Vent holes wont do a thing unless you have through hub exhaust. ...
2. Labbing is only good for the top end and maybe mid range. It actually allows more flex in the blades because they are thinner, that bad is for hole shot.
3. Going down one pitch and then having it labbed may get you the hole shot you want while keeping the same top speed.
4. Try a 5 blade.
5. All boats and props are different try as many as you can.

you didn't see my vent holes drilled in the prop vid....

here we go again..:rolleyes

 

[HavaToon]

you didn't see my vent holes drilled in the prop vid....

here we go again..:rolleyes

Ok Mr. Know it all, who doesn't know it all. Enlighten me and the RDP community with your video and infinite wisdom.



Now I'll enlighten you with a little knowledge easily found on the internet...

aer?ate
ˈ erāt/
verb
verb: aerate; 3rd person present: aerates; past tense: aerated; past participle: aerated; gerund or present participle: aerating
introduce air into (a material).
"she would aerate the lawn with high heels"

The purpose of vent holes is to aerate (introduce air) the water allowing the propeller to spin more easily into the engine torque RPM range. You introduce air via the exhaust gas coming through the hub. So my statement is true "vent holes won't do a thing unless you have through hub exhaust".

Directly from Mercury's website:

On acceleration, exhaust is drawn out of the vent hole located behind each propeller blade. When the next propeller blade strikes this aerated water, less force is required to push through the aerated water versus solid water. This allows the engine RPM to rise more rapidly. Once on plane speed is reached, water flowing over the vent holes seal the exhaust gas in the hub, allowing the propeller to again operate in solid non-aerated water. By varying the size of the exhaust vent hole, the rate at which the engine RPM rises can now be controlled.

And in case you only trust videos:

<iframe width="560" height="315" src="https://www.youtube.com/embed/UFmjl2aFhgw" frameborder="0" allowfullscreen></iframe>


I used to be a know it all, then one day I realized that wasn't even close to the case. Now if you can prove the above to be wrong or what I stated in the thread as incorrect I will have no problem with being the bigger person and admitting it.

Go enjoy a day on the water and relax.:thumbsup:thumbsup:thumbsup

 

[Runs2rch]

OP have you tried a 23 Rev 4? It should do everything you want. With the 375hp mag I think it would be perfect. More overall lift.

 

[CobraDave]

I haven't tried any other props. I kinda just said f it and decided to cut it. The prop shop made me feel comfortable about it. Said if I didn't like it bring it back. We will see.

 

[LargeOrangeFont]

Very interested in your results.

I keep drooling over the orange and grey scheme on your boat.

 

[CobraDave]

Well I have ran the boat with the prop and overall I am happy I did it.

When I hit the throttle to start the prop grabs every bit of the way. Before it seemed like it slipped a little. It wasn't a night and day difference of planing like I'd hope for but noticeable.

Mid range I seem to have more power when I hit the throttles again, say from about 3200 to WOT. That part was noticeably better. As far as top speed, I couldn't really tell. I was carrying four adults and two kids with full tanks and other shit for the day. I think it went to 4800 Rpms at about 107 degrees. I think it would probably hit the 5000 mark with a lighter load and cooler weather. So I am pleased. No desire to continue messing with props. Sorry it took so long to update.

 

[LargeOrangeFont]

Thank you for the update. I think I am going to try a stock 24 pitch first and then take it to have labbed. I have been looking for a used Bravo 1 24 pitch prop to take in for the work.

My boat currently has that slipping feeling on take off as well.

I had the prop on my previous boat worked on a bit (not a full lab) by Hill Marine and the mid range and throttle response is where I noticed big improvements. That was with a Solas prop. Overall it was smoother and it picked up a MPH or two it seemed like.

 

[LargeOrangeFont]

Wanted to update here. I changed my prop and it made a very positive difference. I want from a stock B1 22 pitch to a B1 24 pitch.

The 22 slipped badly if I gave it too much throttle from a start. It topped out at about 61 MPH at 5400-5450. I hit the rev limiter in the cooler months.

The 24 gets on plane much better because it does not slip. I can lay into the throttle and it gets to plane and goes. It picked up 2 MPH on the top end, running 63 MPH at 5100-5150 RPM. The biggest change is in the midrange. I picked up between 4-6 MPH at varying cruising RPMs.

Example: With the 22 I was going 47 MPH at 4700 RPM. With the 24 I was hitting 52-53 MPH at 4700 RPM. I am very happy with the feel and increased efficiency at cruising speeds. The only downside is that response is just slightly muted when I blip the throttle at speed. I am sure this is a function of the increased efficiency and loading the motor slightly more with the bigger prop.

All testing was done via GPS on the same day this week. It was about 100 degrees out.

This was a used 24 prop I found on Ebay. I took it to Hill Marine to have it refurbished and it came back looking brand new.

 

[FreeBird236]

Everything sounds like what would be expected, and seems like 5150 is close enough to redline for WOT.

If you find over time that although you're using less Rpm but you're getting poorer mileage, you may be slightly over propped.

On my 496HO I can run a 26 B1 and get better midrange, but WOT in the heat is only about 4950 -5000 instead of 5150, so I usually run the 24 B1 to be safe.

 

[LargeOrangeFont]

That is a good point. Honestly the boat feels better all around with this 24 prop. It does not sound or feel labored at all, but I will watch the fuel consumption.

I'm going to run it again with the family in it and see how it feels. I may take it back to Hill and get it labbed to see what it will do.

My friend has a boat the same size with an identical engine and drive package. He's had a 24 pitch prop on his for as long as he's had the boat with no issue, but we'll see what my boat likes longer term.

 

[BajaMike]

When its me the wife and kid the prop does the job. If you fill both gas tanks, add a person or two, the boat is real back end heavy and my 24p bravo 1 takes a little bit of work to plane. My goal would be to keep most of my top speed and improve my hole shot. Would it benefit me to have my prop labbed or go down a size? How much speed would I loose if I went down a size?

I have a 23 ft Cobra Razor with a 496 mag.

Go down a size....you are not just getting on plane slowly, but you are straining your engine and entire drive train.