H7 vs. 1450

[Blackout]

Which prop would be easier for an engine to spin? Both completely stock.

Thanks.

 

[Tim_Duggan]

The 1450 stock is a very ordinary prop. The H7 stock is already cupped and has less diameter. Ive never tried a stock 1450 verses a stock H7, but I'd guess the stock 1450 would be easier to spin, but slower.

 

[Paul Traufler]

On my 21 rigger I ran the H7 and it was radar'd at 60 MPH, came in and switched to the 1450 and right back out for another pass, 61 MPH. If the motor RPM was different it was only by a VERY small amount. As for what want worked best, the H7 was a bit easier to launch, and the boat handled just a bit better, but either one produced nearly the same end result. Dropped to a 1445 that was cupped up some as a next step, 64 MPH BUT WAY easier to launch, and handles even better, and yes the NR was spinning up more RPM. Those 21 motors like to spin up over low end grunting. So in the end I'd say these two props (stock) are almost the same as far as speed/RPM goes. Perhaps the actual boat hull would make one prop a bit better than the other one also.

 

[anthony_marquart]

Can you give some details on the rest of your setup?

On my 21 rigger I ran the H7 and it was radar'd at 60 MPH, came in and switched to the 1450 and right back out for another pass, 61 MPH. If the motor RPM was different it was only by a VERY small amount. As for what want worked best, the H7 was a bit easier to launch, and the boat handled just a bit better, but either one produced nearly the same end result. Dropped to a 1445 that was cupped up some as a next step, 64 MPH BUT WAY easier to launch, and handles even better, and yes the NR was spinning up more RPM. Those 21 motors like to spin up over low end grunting. So in the end I'd say these two props (stock) are almost the same as far as speed/RPM goes. Perhaps the actual boat hull would make one prop a bit better than the other one also.

 

[shoboat]

Paul,

Try a H-5 next time, I think you will like it even more.

1445=2.50" of pitch; 45 mm dia.

1450=2.73" of pitch; 48 mm dia.

H-5=2.70" of pitch; 45.50 mm dia.

H-6=2.81" of pitch; 46 mm dia.

H-7=2.85" of pitch; 47.50 mm dia.

These are all measured figures on a Wood pitch gauge.

Too much diameter and excessive cup is what slows down 21 Hydros motors.

Pitch x RPM = MPH Pretty simple math fellas.

Thanks For Reading,

Mark Sholund

Props-4-U

231.590.3023

 

[Jim Mamaril]

My JAE with a T21M likes a 1452 B/C 3.00" Pitch/ 4.09" T.E. Cup, 52.5 mm Dia., Very fast with my set up, the H-7 is not quite as fast but handles a bit better.

 

[Blackout]

Thanks for all the info, everyone!

A couple days ago I ran my JAE 21 for the first time with a stock H-7 and a brand new Novarossi 5-port. I couldn't get the engine even close to on pipe. The boat was puttin around at about 30 mph. Part of the problem was probably the engine was too rich and I ran out of time to try more tuning. I think a smaller prop will help and it sounds like the 1450 might work a bit better. I should have bought a 1445. I'm picking up a Zippkit Mod 1450 this weekend at a race.

 

[Tim_Duggan]

A nova should pull that H7 in a JAE. I run a H7 with 3.75" cup on my FF21 and it doesn't have the benefit of the rear ski. What is your head clearance set to?

 

[John Knight]

A 1450 reduced to 45MM is an excellent prop. A stock 1450 is generally quite large for many 21 engines & boats, especially a NR 5 port. My NR RX21's do not like the stock prop. Cut them down and they run very well.

An H-7 will run on my NR's all day long and run fast. Stock or pitched up, they are good for me.

 

[Glenn Quarles]

Thanks for all the info, everyone!

A couple days ago I ran my JAE 21 for the first time with a stock H-7 and a brand new Novarossi 5-port. I couldn't get the engine even close to on pipe. The boat was puttin around at about 30 mph. Part of the problem was probably the engine was too rich and I ran out of time to try more tuning. I think a smaller prop will help and it sounds like the 1450 might work a bit better. I should have bought a 1445. I'm picking up a Zippkit Mod 1450 this weekend at a race.

Craig, check the head clearance (did you remove at least one of the alum shims?) and make sure the motor is getting up to temp (reduced/no water). And if the motor is brand new, then don't be surprised if it take awhile to break-in.

GQ

 

[Paul Traufler]

Blackjack 21 hydro, NR 5 port STOCK except for the low speed needle is removed (Glenn Q. can do this mod for you) with head clearence set to .009, 50% nitro, Irwin S pipe, I do not recall the pipe length I have. Boat weighs in at 4 lbs, 2 oz without fuel. The water exit has been reduced to keep the engine temp. inside the operational range. There is nothing super special here, off the shelf parts, tuned together to work is all.

Can you give some details on the rest of your setup?

On my 21 rigger I ran the H7 and it was radar'd at 60 MPH, came in and switched to the 1450 and right back out for another pass, 61 MPH. If the motor RPM was different it was only by a VERY small amount. As for what want worked best, the H7 was a bit easier to launch, and the boat handled just a bit better, but either one produced nearly the same end result. Dropped to a 1445 that was cupped up some as a next step, 64 MPH BUT WAY easier to launch, and handles even better, and yes the NR was spinning up more RPM. Those 21 motors like to spin up over low end grunting. So in the end I'd say these two props (stock) are almost the same as far as speed/RPM goes. Perhaps the actual boat hull would make one prop a bit better than the other one also.

 

[Paul Traufler]

Mark it is funny to suggest the H5, I was looking at testing this option soon anyway, as I do think it would make for a good prop on the 21. I agree that these motors want to spin up, no 4 stroke lugging for them!

Paul,

Try a H-5 next time, I think you will like it even more.

1445=2.50" of pitch; 45 mm dia.

1450=2.73" of pitch; 48 mm dia.

H-5=2.70" of pitch; 45.50 mm dia.

H-6=2.81" of pitch; 46 mm dia.

H-7=2.85" of pitch; 47.50 mm dia.

These are all measured figures on a Wood pitch gauge.

Too much diameter and excessive cup is what slows down 21 Hydros motors.

Pitch x RPM = MPH Pretty simple math fellas.

Thanks For Reading,

Mark Sholund

Props-4-U

231.590.3023

 

[Blackout]

Thanks for all the info, everyone!

A couple days ago I ran my JAE 21 for the first time with a stock H-7 and a brand new Novarossi 5-port. I couldn't get the engine even close to on pipe. The boat was puttin around at about 30 mph. Part of the problem was probably the engine was too rich and I ran out of time to try more tuning. I think a smaller prop will help and it sounds like the 1450 might work a bit better. I should have bought a 1445. I'm picking up a Zippkit Mod 1450 this weekend at a race.

Craig, check the head clearance (did you remove at least one of the alum shims?) and make sure the motor is getting up to temp (reduced/no water). And if the motor is brand new, then don't be surprised if it take awhile to break-in.

GQ

Hi Glenn,

Yup, engine is brand new, very tight still. I will take one shim out and reduce the water. I am running only 25% nitro. Would that mean I should take more shims out or does it not matter? Do I need to worry about torque specs for tightening the head back on?

Thanks,

Craig

 

[Glenn Quarles]

Thanks for all the info, everyone!

A couple days ago I ran my JAE 21 for the first time with a stock H-7 and a brand new Novarossi 5-port. I couldn't get the engine even close to on pipe. The boat was puttin around at about 30 mph. Part of the problem was probably the engine was too rich and I ran out of time to try more tuning. I think a smaller prop will help and it sounds like the 1450 might work a bit better. I should have bought a 1445. I'm picking up a Zippkit Mod 1450 this weekend at a race.

Craig, check the head clearance (did you remove at least one of the alum shims?) and make sure the motor is getting up to temp (reduced/no water). And if the motor is brand new, then don't be surprised if it take awhile to break-in.

GQ

Hi Glenn,

Yup, engine is brand new, very tight still. I will take one shim out and reduce the water. I am running only 25% nitro. Would that mean I should take more shims out or does it not matter? Do I need to worry about torque specs for tightening the head back on?

Thanks,

Craig

Craig, yes for 25% you may want to take out the copper shim also (this will leave you with one alum shim and the head clearance should be about .006"...measure to make sure you don't crash the piston into the head button!). If you don't have a torque screwdriver just try to get a good feel and always tighten it the same.

GQ

 

[Andy Brown]

The 1450 and H-7 are too big for 25% nitro.

A stock 1445 would be much better and don't make the pipe too short. Keep it longer than everyone would suggest for 60% nitro.

The EGT of 25% is higher than that of 60% nitro, so the same rpm can be realized with a slightly longer pipe.

Just prop it until you get the RPM up where it belongs.

Also .006" clearance is way too close for 25% nitro. That clearance will advance the ignition point too much and you will actually loose torque and power.

.018" -.024" would be much better. The stock clearance is probably in that range, so just leave the shims as they came.....and prop down.

This combo will run best with a hot head temp. so give it very little water...or none according to your weather conditions.

 

[Ted buckley]

The 1450 and H-7 are too big for 25% nitro.

A stock 1445 would be much better and don't make the pipe too short. Keep it longer than everyone would suggest for 60% nitro.

The EGT of 25% is higher than that of 60% nitro, so the same rpm can be realized with a slightly longer pipe.

Just prop it until you get the RPM up where it belongs.

Also .006" clearance is way too close for 25% nitro. That clearance will advance the ignition point too much and you will actually loose torque and power.

.018" -.024" would be much better. The stock clearance is probably in that range, so just leave the shims as they came.....and prop down.

This combo will run best with a hot head temp. so give it very little water...or none according to your weather conditions.

I think Andy is dead-on. Hey Andy, Lance & I just had this conversation about an Hour ago, and we both have the Nova 7Port. We only have 1 Aluminum shim taken-out leaving the 1 brass & 1 Aluminum shim. Bringing it down to (I believe .010 clearance as opposed to the 0.006). We talked about taking the Brass out, but I already run 40% on my motor and just thought that this would be beating on the motor too much.. With how my wife feels about me spending all kinds of money on new motors all the time, I'm opting to keep it in.. This mean's that I can push the 1450 with a very slight cup on it/Pipe out a little farther - and it's purring like a kitten.

 

[Glenn Quarles]

Thanks for setting me straight Andy!

Glenn

 

[Mike Larson]

Andy it must be magic.... as, we have/started with that exact theory on Adam's bone stock 5 port.....25% ( We did clearance the motor, to .010, though).....

the '45, we used as a break in prop.... as the motor came in, we cupped it up....... spun to limit,, and he has now advanced,( 45%) and we're around the 1450's seasoning to taste...... his motor came in very strong, and the 1452 reduced looks to test again tommorow.....

Running the cooper/s, around 8" to the weld, or 7.5 at the center of the band......

It's pretty serious fun honing the boat down, and it responds easily with the strut/AOA variables taken out of the equation.....

question applied: the octura 14 series almost have unwanted lift we are trying to allieviate..... seeing the propellor actually rotating as the boat passes by, while cool, has me looking at unwarranted AOA possibilities ( I look, strive for a level tub, no water spray operation on passes).... it's not exponential, but, relieveing a hair of the lift at least on Adam's platform would help.....

My boat in the video, as both of our platform's are, dont have the layed down rooster, ( wasted thrust, and speed).... Cupping to wean the thrust cone down is where we are at....... another sunday....... thanks Mike

 

[Blackout]

Well, I ran my JAE 21 again today with a Zippkit Mod 1450 and reduced water. The speeds are much better now. Thanks.

 

[Brad Christy]

Guys,

I know this is a thread comparing the H7 and the 1450, but have any of you 21 hydro guys worked with the H10 at all? I was running a de-tongued (otherwise stock) H10 at Hobart. I totally tanked the first and third heat, but in the second heat I think it was PLENTY fast enough for nearly anybody to contend with, and I don't have the engine really screaming yet.

Mark,

What's the stock numbers for the H10?

Thnaks. Brad.

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