Prop to try? Same post, both sites.

[Just Say N20]

Long-winded Bill is back.

I'll just toss this out there to see if someone might have something hiding on a shelf that might be of use. Although I can't imagine why someone would have a 28" 4-Blade Left Hand prop just sitting around.

As some know, Ed Donnelly and I traded boats last summer. The Criterion, of which I am now the proud owner, has had at least 3 "stages." It came from the factory with a 370 hp 454. The boat is a left hand drive (the proper side from which to drive), and has a TRS drive. In the original configuration, I assume the boat ran a 21" 3-blade cleaver. I have 2 of these props.

Then, Ed, in true Ed fashion, went full in and had a 1,000+ hp twin turbo engine built for the boat. Perhaps he was just curious to see what 100+ mph felt like in a 22 versus how it felt in a 16. I don't know. But for this engine, he ran a 30" 4-blade Bravo I prop that has been reworked to a 31" pitch.

After experiencing the 100+ mph rush in the 22, Ed decided that it was a "bit much" and put the original 454 back in, with the addition of a Weiand supercharger. Horsepower is unknown. Unfortunately, shortly after this engine was installed, Ed's health prevented him from using the boat more than a few times. In this configuration, the boat ran either a 24" 4-blade Bravo I, or a 24" 4-Blade Intimidator Q-IV.

Hang with me here.

The blower HAD a 3.48" top pulley, which produced just under 3 lbs of boost. I have run both the 24" Intimidator Q-IV, and the 31" Bravo I with this configuration. The 24" Intimidator Q-IV seems to be a very good match for this boat, kind of. With it, the boat runs 78 GPS, but at 5,800 rpms. I didn't build the engine, so I'm not exactly sure what is in it, but I'm not comfortable running a 454 at that kind of rpms. By the way, it sounds AWESOME!

The 31" Bravo I prop ran 73 mph at 4,500 rpms. Surprisingly the boat has no problem planing with it. As I expected, it is too much prop for the engine to really run.

Trueser also let me try one of his labbed 26" 3-Blades that was maybe a 27 after the work. The boat hated it! Best I could get was 5,000 rpms and barely 70 mph.

Now, the plot thickens. My son-in-law and daughter gave me a smaller (3.04" I believe) pulley for Christmas. I did some engine "tuning" prior to swapping pulleys. This was relatively easy, as the boat has an AFR gauge, and dual exhaust temp gauges. I got the carb jetting to where the AFR numbers are good.

Results running the smaller pulley, and the 31" Bravo I are as follows. The engine now has 5 lbs of boost, and ran at 4,800 rpms. However, the top speed remained at 73. It seems that on this boat, with the TRS drive, that prop slips a lot. It starts to lose grip fairly early when trimming, and continues to get worse.

Based on how the Intimidator Q-IV runs, I would love to try a 28" one of those. I have NOT run the boat with the 24" Intimidator and the higher boost. Based on picking up 300 rpms with the 31" prop, I would probably pick up 500 rpm with the 24. And I'm already at 5,800, so as Monty Python would say, "5 is right out." You're welcome Ghost.

The catch is that this is a Left Hand set up, so I would need a left hand prop. I have the insert for Mercruiser props.

I am going to put the 24" 4-Blade Bravo I, and the two 21" 3-Blades cleavers for sale. I will keep the other 2 until I find an appropriate replacement.

If anyone has a prop that might be interesting to try, and are willing to let me try it, let me know.

[Conquistador_del_mar]

Bill,
I would highly recommend trying this prop with your setup description. The Rev4 hooks up and responds well on every deep V boat I have tried it on including TRS drives. Another Bill

http://www.ebay.com/itm/MERCURY-MARI...ade1c8&vxp=mtr

[Just Say N20]

Thanks Bill.

Thanks for taking the time to post the link. I'm not sure moving from a 24 to a 25 would be enough increase in pitch. Generously, 150 rpm loss for every inch of increased pitch is all I have ever seen. I would like to keep the rpms around 5,200 max.

I believe I would need at least a 28', maybe 29" pitch. A guess would be the engine is putting out maybe 550 hp.

[Conquistador_del_mar]

The Rev4 hooks up like nothing else I have seen. I'm running 74MPH in my 28' Warlock at somewhere around 5100RPM with a 25P Rev4. Might be worth trying.

[Greg Guimond]

The Mercury Rev4 is the same geometry as the Tempest Plus and should work very well on the Critter. The prop is designed for deeper drive depths and has a lot of blade area. They tend to run a little stiff compared to a Bravo prop which tends to run a touch under pitch. Another prop worth a look would be a Turbo Fusion 4 if the drive is higher but it won't be as good "all around" as the Merc in your app I suspect.

[Carl C]

All of your speed results seem low for a blown 454. Your prop choices and results are all over the place. Bravo 1s are overrated in pitch by 1 or 1 1/2. I'm running a 30p Bravo 1. I could not pull a 30p in any other prop that I am aware of. I would shoot for at least 5,400 RPM. Just some thoughts. I don't know what to tell you on prop choices based on your previous results. . . . . .

[gcarter]

FWIW, Catch22 (Jim Collins) ran a supercharged 454 w/a 30 or 31
Hydro Q4 and ran around 92. It seemed to be a worry free/ drama
free setup.
Bravo w/-2" lower.
This is the way I remember it anyway.

[Just Say N20]

Interesting. Bravo shorty is probably a big help. I don't know if TRS drives are usually considered "fast."

Carl, the TRS drive could also be why the speeds are lower than what you would expect.

[gcarter]

Interesting. Bravo shorty is probably a big help. I don't know if TRS drives are usually considered "fast."

Carl, the TRS drive could also be why the speeds are lower than what you would expect.

Bill, the Merc "number" racing lowers are based on TRS uppers.
You'd have to decide which is the cheapest way to go, i.e., the cost of a Bravo and a shorty,
VS. the cost of a Merc racing lower.....
You can frequently find them on eBay and other places.

[Just Say N20]

Being solidly "middle age" at 59, and not making an income that is dependent on how fast the Critter goes, I am just looking for a prop that is a good match with the engine as it currently performs.

I'm sure a numbered drive would be awesome, however squeezing every last mph out of this setup is not my priority at the moment.

[Greg Guimond]

I have a Turbo Fusion 4 27" that I would ship you to try out if you ship me (to CT) your Bravo 24" prop to do the same on my boat. I also have the same Turbo prop in a 26".

[MDonziM]

Bill,

My 2c on several things mentioned here: As for props, I would have thought that a TRS which were generally rigged deep as to X-dim that a 3 blade mirage plus would be best... If the 4 blades are better, the Bravo 1's and Hydramotives are similar but I believe the q4's might not give as much bow trim/carry. I don't know anything about Rev4's or Fusion's. If you have a B&M 174/Weiand 177 blower running 4.5-5lbs of boost on an old Merc 420 spec built 454 you should have 550hp. When you find the right prop I would not run that motor over 5200 rpm as the supercharger is just producing heat past that rpm and a very inefficient charge.

- M

[Just Say N20]

I have a Turbo Fusion 4 27" that I would ship you to try out if you ship me (to CT) your Bravo 24" prop to do the same on my boat. I also have the same Turbo prop in a 26".

Happy to send the Bravo I 24" your way. You do remember they are all LH props. . .

If you still want it, pm me your address. Likewise, if the 27 is a LH prop let me know.

[Just Say N20]

Bill,

My 2c on several things mentioned here: As for props, I would have thought that a TRS which were generally rigged deep as to X-dim that a 3 blade mirage plus would be best... If the 4 blades are better, the Bravo 1's and Hydramotives are similar but I believe the q4's might not give as much bow trim/carry. I don't know anything about Rev4's or Fusion's. If you have a B&M 174/Weiand 177 blower running 4.5-5lbs of boost on an old Merc 420 spec built 454 you should have 550hp. When you find the right prop I would not run that motor over 5200 rpm as the supercharger is just producing heat past that rpm and a very inefficient charge.

- M

Marshall, your statements are spot on. Trueser thought the 3-blade Mirage would be good, but the boat didn't like it at all. Too bad, as it was a labbed prop. The drive is a little deep. I wish I knew why the Q-IV 24" seemed like a magic prop. I thought 78 for that set up was really good. Ran well and was very predictable. But spinning the engine into furnace territory.

I was told the engine was the 370 hp 454. I'm new to the BBC world, but Ed told me the engine had forged internals.

It is the small Weiand blower. Good low end and mid-range performance, but definitely a heat machine on top end.

[Ed Donnelly]

I bought the Criterion from John Chisholm and it was a 370 hp.
E erything is forged. Ralph at Rapid my engine builder confirmed everything.
Sorry to hear about the starter motor. Still no steering in the 16...Ed