# HpxT with 70 Yamaha 2 stroke



## EvanHammer (Aug 14, 2015)

Poonphish said:


> I really don’t want to put a jack plate on my HpxT and was wondering if anyone can recommend a 3 bladed prop that can give me better performance than the Powertech 4 blade I am running now. I know that Jack foreman is the best but he only wants to deal with you after you put a jack plate on, and as I mentioned I really can’t do that right now. My top speed is only26 @ 5200rpm. Love the boat just wish I could eak out a few more mph without spending a lot of money...... thank you for your taking the time with this.......John


call Louie Baumann and see what he says if Crossroads won't prop you without a jackplate. Almost positive Louie will push a big 3-blade even if you didn't ask for one.


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## Smackdaddy53 (Dec 31, 2012)

EvanHammer said:


> call Louie Baumann and see what he says if Crossroads won't prop you without a jackplate. Almost positive Louie will push a big 3-blade even if you didn't ask for one.


Jack won’t sell a holeshot prop to a guy with no jackplate because they are made to run very high or they bog the motor down. Louie would but that’s how he is.
I’d look at a Powertech with 1X cup. I’m sure Jack could tell you which one if you asked and can get them for you since he probably designed it.


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## SomaliPirate (Feb 5, 2016)

What Powertech are you running right now? I'm running a 4 blade SCD4R15P on a Yammy 60 and seeing 30-31 out of my 17T.


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## EvanHammer (Aug 14, 2015)

How high is your motor mounted? I like jackplates and know lots of guys swear by them on that skiff but that skiff can run awfully shallow without a jackplate. Eric Glass, Bill Hagen and others all guided the lower laguna for years without a jackplate when they were running HPX-Ts. 

I ran an HPX-T for 7 years and never had a jackplate. It would run shallow enough to feel the hull bounce off the bottom, get up where it wouldn't float on a soft bottom, and consistently hit 36 mph - you could see 37.5 every once in awhile.


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## Smackdaddy53 (Dec 31, 2012)

EvanHammer said:


> How high is your motor mounted? I like jackplates and know lots of guys swear by them on that skiff but that skiff can run awfully shallow without a jackplate. Eric Glass, Bill Hagen and others all guided the lower laguna for years without a jackplate when they were running HPX-Ts.
> 
> I ran an HPX-T for 7 years and never had a jackplate. It would run shallow enough to feel the hull bounce off the bottom, get up where it wouldn't float on a soft bottom, and consistently hit 36 mph - you could see 37.5 every once in awhile.


That was probably your lower unit dredging bottom, not the hull. (Sarcasm)


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## EvanHammer (Aug 14, 2015)

Smackdaddy53 said:


> That was probably your lower unit dredging bottom, not the hull. (Sarcasm)


Might have been my taint dredging bottom the way I puckered up on those runs.


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## Mike C (Feb 27, 2017)

SomaliPirate said:


> What Powertech are you running right now? I'm running a 4 blade SCD4R15P on a Yammy 60 and seeing 30-31 out of my 17T.


I have a Tailfisher (same basic boat) with a TLR 60 running the same prop with a 13p. I did have it cleaned up and some moderate cupping done by the folks at Admiral.
12 gallons of gas, three batteries, trolling motor, fishing gear and a 45 Yeti I get 30.6mph a 6000 rpm.

Loaded lighter I get 31mph plus a touch more depending on wind. 
One of these days I'll pull everything out just to see if it will hit 33mph, but it's not high on the priority list. 

The Yamaha performance bulletin is almost an exact duplicate of my performance except at the 4500 rpm range. 

Sounds like the OP is over propped a bit.


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## SomaliPirate (Feb 5, 2016)

Mike C said:


> I have a Tailfisher (same basic boat) with a TLR 60 running the same prop with a 13p. I did have it cleaned up and some moderate cupping done by the folks at Admiral.
> 12 gallons of gas, three batteries, trolling motor, fishing gear and a 45 Yeti I get 30.6mph a 6000 rpm.
> 
> Loaded lighter I get 31mph plus a touch more depending on wind.
> ...


That's what I was thinking. Also, I think low 30's might be the top end for these hulls regardless of power or prop. You just won't win many races in a tunnel, unless it's straight over a sand bar.


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## Mike C (Feb 27, 2017)

And it do the sand bar thing quite well. 
I love how it will shift as the water compresses under the hull, settles down and then does the shift again as it comes off the bar


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## zthomas (Jan 14, 2014)

Mike C said:


> I love how it will shift as the water compresses under the hull, settles down and then does the shift again as it comes off the bar


Yeah, that's neat the way you can feel the running attitude change when it gets really skinny, kind of like the ground effect in an airplane.


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## Bruce J (Mar 4, 2018)

Maybe I just missed it, but don't see what prop you have on there now. It sounds like it might have a least a couple inches too much pitch if you're stalling out at 26mph and 5200rpm. I had the same boat set up for years and ran a 4-blade "Lifter" prop - I think since purchased by Baumann. Unfortunately I don't remember the specs on it. I could get up to about 34mph as I recall, and your boat should definitely do the same unless you're having engine issues.


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## Poonphish (Feb 23, 2015)

I am running a power tech PFS4R14P....13 1/4 diameter. Someone suggested I try the Powertech NRS3R14PPYM90. I have talked with Jack Foreman who is very knowledgeable about tunnel hulls and propping them but he says I have to install a jack plate on boat to begin with and I really don’t want to do that. I am just trying to get my boat to run 30 or 31mph and turn what the engine is designed to do which is 6000rpm. I do appreciate any and all input on this.


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## Bruce J (Mar 4, 2018)

I'm not familiar with those specific props, but I can't believe a 2-stroke 70hp Yamaha couldn't spin a 14" prop faster than 5200rpm, or move you faster than 26mph. Those are really bad numbers for that boat/motor combo. Are you positive the motor is running properly?


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## Poonphish (Feb 23, 2015)

Absolutely. Checked engine by best mechanic here in Ft Myers. Do they ever stamp the specs wrong on the prop???? I am hoping this new powertech will take care of problem. Hopefully be able to try the new prop this weekend if weather cooperates.


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## Smackdaddy53 (Dec 31, 2012)

My prop is a 14” diameter 14 pitch three blade with triple cup and I can get my motor to run 5200rpm at 33mph with two big guys and a full load BUT that’s with a jackplate jacked up, trimmed out with tabs down a little. Being a triple cup makes it more like a 15 pitch with no cup. I think you should try raising your motor a couple of bolt holes if possible. Can you post photos looking straight even with the bottom of the hull and with the motor trimmed level (prop shaft parallel with hull bottom) so I know where your motor is in comparison to mine?


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## Seymour fish (May 13, 2018)

Poonphish said:


> I am running a power tech PFS4R14P....13 1/4 diameter. Someone suggested I try the Powertech NRS3R14PPYM90. I have talked with Jack Foreman who is very knowledgeable about tunnel hulls and propping them but he says I have to install a jack plate on boat to begin with and I really don’t want to do that. I am just trying to get my boat to run 30 or 31mph and turn what the engine is designed to do which is 6000rpm. I do appreciate any and all input on this.


The PFS is a hell of a good prop. Drop down to a 13 pitch and get the motor up some


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## Seymour fish (May 13, 2018)

Seymour fish said:


> The PFS is a hell of a good prop. Drop down to a 13 pitch and get the motor up some


Example: PFS 13-4 blade hpxt/ F70. Motor halfway up on jack plate, lotsa drag, will not wind out. Motor up some, rpm’s rise at least 500 or better at same throttle, and speed picks up. Proper trim gives 6100-6200 with excellent water pressure. That setting, when you find it, works great in most conditions and will cruise in 5” on hard sand, which is adequate for most. Hole shot is excellent. Tops out 33 mph.


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## Smackdaddy53 (Dec 31, 2012)

Seymour fish said:


> Example: PFS 13-4 blade hpxt/ F70. Motor halfway up on jack plate, lotsa drag, will not wind out. Motor up some, rpm’s rise at least 500 or better at same throttle, and speed picks up. Proper trim gives 6100-6200 with excellent water pressure. That setting, when you find it, works great in most conditions and will cruise in 5” on hard sand, which is adequate for most. Hole shot is excellent. Tops out 33 mph.


The F70 and 70TLR can’t be comparably propped beacause they are just completely different motors.


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## Mike C (Feb 27, 2017)

Smackdaddy53 said:


> The F70 and 70TLR can’t be comparably propped beacause they are just completely different motors.


Is that due to the different lower units and gear ratios?


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## Smackdaddy53 (Dec 31, 2012)

Mike C said:


> Is that due to the different lower units and gear ratios?


No, the F70 is a four stroke with less torque and a much higher max RPM (6400?). The 70TLR is a two stroke with a ton of low end torque and a lower max RPM (specs show 5500 but the actual motor rating is 5850).


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## Seymour fish (May 13, 2018)

Smackdaddy53 said:


> The F70 and 70TLR can’t be comparably propped beacause they are just completely different motors.


Mac, Look at the torque curves, top end HP. He can’t turn his 14 pitch with a 2-stroke with better bottom end torque than an F70. If he got the height right, Betcha a PFS 4-blade in 13 pitch would bite and hold, and turn on up. Do you wonder how the wimpy F70 turns that prop ? Do you wonder if my cheater slicks are in ?


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## Mike C (Feb 27, 2017)

I have the TLR 60 on my Tailfisher and honestly thought the only difference was the lower unit. 
Mine will flicker between 5950 and 6000 all the time and occasionally hit 6100.
I don't recall ever seeing 6200 unless the rev limiter kicks in during a tight turn blow out. 
I had to learn to use a bit of tabs and trim it down a little for running the mangroves.


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## Smackdaddy53 (Dec 31, 2012)

Seymour fish said:


> Mac, Look at the torque curves, top end HP. He can’t turn his 14 pitch with a 2-stroke with better bottom end torque than an F70. If he got the height right, Betcha a PFS 4-blade in 13 pitch would bite and hold, and turn on up. Do you wonder how the wimpy F70 turns that prop ? Do you wonder if my cheater slicks are in ?


I don’t know what cheater slicks are but the rest sounds good! 
There’s a lot more to props than diameter, pitch and cup but I guess a shelf prop will fit his needs. I’ll go out and look at the Powertech 4 blade that came on my 2 stroke 70 when I bought the boat a couple of years ago and post a photo of the model number. My HPX Tunnel did not have a jackplate when I bought it and ran about 30 with that prop and a light load but the holeshot sucked and it blew out in corners. I think I could get RPMs up to about 5100 with that prop which left a lot to be desired as far as top end speed.


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## Seymour fish (May 13, 2018)

Smackdaddy53 said:


> I don’t know what cheater slicks are but the rest sounds good!
> There’s a lot more to props than diameter, pitch and cup but I guess a shelf prop will fit his needs. I’ll go out and look at the Powertech 4 blade that came on my 2 stroke 70 when I bought the boat a couple of years ago and post a photo of the model number. My HPX Tunnel did not have a jackplate when I bought it and ran about 30 with that prop and a light load but the holeshot sucked and it blew out in corners. I think I could get RPMs up to about 5100 with that prop which left a lot to be desired as far as top end speed.


Mac, we are on the same page, just coming at possible solutions from different angles. Once you find the best compromise prop, longevity comes into it. Lotsa “meat” in a PFS. 300 hours of running sand. Variance in “identical “ off the shelf props too: 5800 with the first one till burned it in, 6100 with the second right outta the box.


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## Smackdaddy53 (Dec 31, 2012)

Ok I dug it out of my boat hatch. Here’s what was on my HPX Tunnel when I bought it and it had no jack plate or compression plate. It was a decent prop, forgot it was ported.


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## Smackdaddy53 (Dec 31, 2012)

NoBait/LuresOnly asked about ported props and I forgot what I knew...the exhaust is expelled through the ports and it helps the prop spin up a little faster. I never really understood why ports are necessary, I figured they are basically adding artificial cavitation to add some prop slip on a prop that needs some slip to run the best. Can the blades not be tweaked to offset whatever the ports add so ports are not needed? I always thought ported props were only for higher horsepower motors until I saw this one.


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## Seymour fish (May 13, 2018)

Smackdaddy53 said:


> NoBait/LuresOnly asked about ported props and I forgot what I knew...the exhaust is expelled through the ports and it helps the prop spin up a little faster. I never really understood why ports are necessary, I figured they are basically adding artificial cavitation to add some prop slip on a prop that needs some slip to run the best. Can the blades not be tweaked to offset whatever the ports add so ports are not needed? I always thought ported props were only for higher horsepower motors until I saw this one.


Shhhhhh ! That porting is top secret


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## Seymour fish (May 13, 2018)

Seymour fish said:


> Shhhhhh ! That porting is top secret


Think high stall speed converter in a drag car. I get 4K or better before she hooks, and Gone. 5/16” ports


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## Smackdaddy53 (Dec 31, 2012)

Seymour fish said:


> Think high stall speed converter in a drag car. I get 4K or better before she hooks, and Gone. 5/16” ports


I like holeshot that will throw you over the transom if you aren’t holding on. Instant grip, not as worried about too end as long as it’s not struggling to break 30. I wasn’t too impressed with that ported 4 blade, it was probably just because the previous owner did what I see and read about others doing...asking a few people then running through several shelf props in a year’s time before they get sick of it and settle for one that’s mediocre at best.


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