Post by: connorstexas on August 02, 2017, 08:42:39 PM
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Post by: GT Jets on August 02, 2017, 10:09:54 PM
i think 4500 is a little low for a boat, my set up is a ford 460, c8 heads, dish pistons, big cam, 750 carb. running a berk 12 jc pump, with a loader under the boat snd ride plate. only getting 4500 rpm out of the boat. any way to get another 1000??
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Throw the 750 away, reduce the cam or increase the compression ratio, cut the impeller down and buy a 80 cubic foot bottle of nitrous oxide...
4,500 RPM is about right to be honest..
GT
Post by: connorstexas on August 03, 2017, 01:46:23 AM
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Post by: mash on it on August 03, 2017, 06:25:17 AM
i think 4500 is a little low for a boat, my set up is a ford 460, c8 heads, dish pistons, big cam, 750 carb. running a berk 12 jc pump, with a loader under the boat snd ride plate. only getting 4500 rpm out of the boat. any way to get another 1000??
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4500 is about right for a BONE STOCK, run-of-the-mill, used pick-up truck motor, with an "A" Impeller.
I run a 350 chevy @ 45-4600 rpm, "A" impeller. Mostly stock, BTW. (750 Holley and Headers)
4500 is ~ 325 hp (A imp.)
5500 is ~ 595 hp (A imp.)
There is no reason a mildly built 460 wont run 5K to 5100 rpm. (475 to 500 HP)
just my $0.02
Dan'l
Post by: connorstexas on August 03, 2017, 06:30:39 AM
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Post by: mach1_557 on August 03, 2017, 11:58:16 AM
My bone stock marine 460 (back up motor) runs 4600-4700rpm on a tight pump and a stainless A with a 750dp mech secondaries. In my 600pound Daytona. You are rite in the ball park. That engine with came stock with a dish (reverse dome) piston. Should be 10to1 comp .
Post by: 76Challenger on August 03, 2017, 12:37:54 PM
1977 Challenger
Post by: mach1_557 on August 03, 2017, 12:42:06 PM
Post by: 76Challenger on August 03, 2017, 02:06:13 PM
but depends what material the impeller is made of . Alum will spin more rpmsThat makes sense. Mine is a stock aluminum A.
1977 Challenger
Post by: connorstexas on August 03, 2017, 05:01:36 PM
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Post by: GT Jets on August 03, 2017, 10:27:12 PM
but depends what material the impeller is made of . Alum will spin more rpms
Absolutely untrue....
Post by: GT Jets on August 03, 2017, 10:29:35 PM
My bone stock 460 with a Berkeley E with an A turns 5200 in a 1000 pound Challenger hull
1977 Challenger
Time to build a pump or buy a new tach....
JMO
GT
Post by: connorstexas on August 03, 2017, 10:47:22 PM
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Post by: GT Jets on August 03, 2017, 10:56:44 PM
what size carb gt?
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Can't miss with an 850, square bore double pumper. Quick Fuel, Holley, Pro Form are all pretty good. Drop the power valve 2" and one up the main jet sizes and it will be silly close...
JMHO
GT
Post by: connorstexas on August 03, 2017, 10:58:36 PM
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Post by: mach1_557 on August 04, 2017, 06:12:37 AM
Anyone can say completely untrue, let's hear some facts and data behind why you think that's untrue. @gtjets I'm very curious .
Post by: Bogger01999 on August 04, 2017, 09:28:42 AM
Post by: connorstexas on August 04, 2017, 12:08:42 PM
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Post by: 76Challenger on August 04, 2017, 03:19:17 PM
Was just rebuilt and has run that since the day the boat was new...
Time to build a pump or buy a new tach....
JMO
GT
1977 Challenger
Post by: GT Jets on August 04, 2017, 06:42:04 PM
Anyone can say completely untrue, let's hear some facts and data behind why you think that's untrue. @gtjets I'm very curious .
Show me on this chart where a stainless turns a different RPM than an aluminum or a bronze.......
I'm all ears.......
GT
Post by: GT Jets on August 04, 2017, 06:47:57 PM
Was just rebuilt and has run that since the day the boat was new...
1977 Challenger
I'm not trying to be a dick..
I just never heard of a 450 HP "Bone Stock 460"....
That engine made about 325 HP when it came from Ford.... Which would put you closer to about 4,600 RPM....
That's all I'm saying. I feel the tachometer is off by 500 RPM...... Or that 460 is built better than you think it is.
GT
Post by: 76Challenger on August 04, 2017, 07:00:25 PM
Not taken personally GT at all. Just saying dad bought the boat new the original Stewart Warner tach always would hit 5200 at WOT. When I swapped the parts from another Challenger with all stock parts I also swapped the tachs so it's now got the second tach in it exact same tach as the original stock tach still hits right at 5200 WOT. The original harman marine hit this and so does the second all original harman I have in it now from the swap. Idk maybe these SW tachs were prone to be wrong just odd that both original tachs and both original engines produce the same result. Again nothing personal just what I have seen this boat do both brand new in 1977 and to this day...you have a much broader knowledge then I do all I have is what I have seen.
I'm not trying to be a dick..
I just never heard of a 450 HP "Bone Stock 460"....
That engine made about 325 HP when it came from Ford.... Which would put you closer to about 4,600 RPM....
That's all I'm saying. I feel the tachometer is off by 500 RPM...... Or that 460 is built better than you think it is.
GT
1977 Challenger
Post by: GT Jets on August 04, 2017, 07:03:44 PM
Not taken personally GT at all. Just saying dad bought the boat new the original Stewart Warner tach always would hit 5200 at WOT. When I swapped the parts from another Challenger with all stock parts I also swapped the tachs so it's now got the second tach in it exact same tach as the original stock tach still hits right at 5200 WOT. The original harman marine hit this and so does the second all original harman I have in it now from the swap. Idk maybe these SW tachs were prone to be wrong just odd that both original tachs and both original engines produce the same result. Again nothing personal just what I have seen this boat do both brand new in 1977 and to this day...
1977 Challenger
If that has the bottom I think it does, that boat better be hitting 82 miles an hour.... Maybe more, at 450 HP with an A impeller....
GT
Post by: 76Challenger on August 04, 2017, 07:09:02 PM
If that has the bottom I think it does, that boat better be hitting 82 miles an hour.... Maybe more, at 450 HP with an A impeller....Lol GT. Now you know a Challenger would be hard pressed to hit that speed at any RPM it's a 1000 pound hull. If both tachs are wrong then they are both wrong is what it is. Your knowledge is very much appreciated.
GT
1977 Challenger
Post by: GT Jets on August 04, 2017, 07:19:52 PM
Lol GT. Now you know a Challenger would be hard pressed to hit that speed at any RPM it's a 1000 pound hull. If both tachs are wrong then they are both wrong is what it is. Your knowledge is very much appreciated.
1977 Challenger
That should be a straight lifting strake Southwind bottom...
Post by: 76Challenger on August 04, 2017, 07:24:28 PM
That should be a straight lifting strake Southwind bottom...Yes I believe it is. I think the Challenger was layed up heavier though not sure where I heard that over the years but I do know the hull was rated at 1000 pounds I don't believe many of the 18 were that heavy...
1977 Challenger
Post by: 76Challenger on August 04, 2017, 07:28:04 PM
1977 Challenger
Post by: 76Challenger on August 04, 2017, 07:40:02 PM
1977 Challenger
Post by: GT Jets on August 04, 2017, 07:45:44 PM
Looking at this 1978 artical in performance boats on Challenger, granted this test boat was a 454 and JG with a B, but the engine specs say max hp 325 at 4600 but further down it shows the calibrated tach hit 5050 and the dash tach hit 4900.
1977 Challenger
Those numbers jive almost perfectly with an impeller chart.... I'm just saying....
GT
Post by: 76Challenger on August 04, 2017, 07:47:45 PM
Agreed. But it does seem to show a difference between engine specs and actual. And even at 5050 rpm top speed was only 61 62 mph
Those numbers jive almost perfectly with an impeller chart.... I'm just saying....
GT
By the way thanks for schooling me here I am learning lol not trying to be combative lol
1977 Challenger
Post by: GT Jets on August 04, 2017, 08:01:04 PM
Agreed. But it does seem to show a difference between engine specs and actual. And even at 5050 rpm top speed was only 61 62 mph
That's what I'm trying to tell you.....
325 HP, smaller impeller, less RPM than you....
Now add 25% HP with a larger impeller at more rpm...
Verdict? I'm feeling 75MPH without the advantage of a calculator.... Betting closer to 80.
Our Southwind goes 70MPH with a small block, I'm thinking headers and trim the wheel and it's good for 75 for miles at a time...
GT
Post by: bobjthomson on August 04, 2017, 08:03:00 PM
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Post by: 76Challenger on August 04, 2017, 08:04:29 PM
1977 Challenger
Post by: 76Challenger on August 04, 2017, 08:08:41 PM
lol GtDude this was not a pissing contest between myself an GT. Just questions and answers
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1977 Challenger
Post by: GT Jets on August 04, 2017, 08:12:44 PM
Gottcha thanks! Hope to sit and have a beer sometime. Been around these crazy boats all my life and don't have even half the knowledge...
1977 Challenger
I'm down for that.... :beer: :beer: :beer:
When I was two years old, I used to fall asleep in the back seat of my dads purple flake and white Olds powered Glencoe..... Towed by a 1967 big block Chevelle SS.....
So I'm right there with you 8)
GT
Post by: 76Challenger on August 04, 2017, 08:18:07 PM
1977 Challenger
Post by: GT Jets on August 04, 2017, 08:23:34 PM
Also have a Sea Doo to dial in.... (I know...LOL)
Post by: 76Challenger on August 04, 2017, 08:27:43 PM
Was actually thinking about heading down to Nacimiento to test the Southwind. Just cut the impeller down another step and want to see what it does....Nice
Also have a Sea Doo to dial in.... (I know...LOL)
I just like the fact San Antonio has shore camping for the motorhome. I am picking up a 95 SPX seadoo and trailer tomorrow to play around with 1977 Challenger
Post by: GT Jets on August 04, 2017, 08:32:29 PM
Nice
1977 Challenger
I have an XP and an SPX, a 650 and a 787. I'm in them virtually nothing (the XP under $300 and the SPX $150 with single trailers for each...).... We normally camp on the beach by the store at Naci... Been a while.
Post by: 76Challenger on August 04, 2017, 08:34:54 PM
I have an XP and an SPX, a 650 and a 787. I'm in them virtually nothing (the XP under $300 and the SPX $150 with single trailers for each...).... We normally camp on the beach by the store at Naci... Been a while.Nice I sent ya a pm so I am not thread jacking anymore lol
1977 Challenger
Post by: GT Jets on August 04, 2017, 08:36:28 PM
Post by: Steveo909 on August 04, 2017, 08:40:34 PM
(Attachment Link)Man I hope my impeller doesn't explode. I'm at about 500 with an aluminum aggressor.
Show me on this chart where a stainless turns a different RPM than an aluminum or a bronze.......
I'm all ears.......
GT
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Post by: 76Challenger on August 04, 2017, 08:46:15 PM
1977 Challenger
Post by: GT Jets on August 04, 2017, 08:46:29 PM
Man I hope my impeller doesn't explode. I'm at about 500 with an aluminum aggressor.
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Loader? What RPM?
I doubt seriously you will have an issue. How old of an Aggressor?
Post by: GT Jets on August 04, 2017, 08:48:17 PM
The spx
1977 Challenger
I feel a race coming on... Need to find someone light. LOL
Post by: Steveo909 on August 04, 2017, 08:49:44 PM
Loader? What RPM?I'm not sure yet. Haven't had time to test the new motor. Maybe next week. It's an A/B cut which I think is equal to a berk A. I'm guessing it will be 52-5400. Has the sport intake grate.
I doubt seriously you will have an issue. How old of an Aggressor?
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Post by: 76Challenger on August 04, 2017, 08:50:41 PM
Lmao your on!
I feel a race coming on... Need to find someone light. LOL
1977 Challenger
Post by: mach1_557 on August 04, 2017, 09:00:04 PM
(Attachment Link)
Show me on this chart where a stainless turns a different RPM than an aluminum or a bronze.......
I'm all ears.......
GT
The chart references at what hp and rpm to change impeller material and that's it . Any person with common sense can figure out that a heavier material will take more force to spin it and keep it spinning .
Post by: GT Jets on August 04, 2017, 09:10:36 PM
The chart references at what hp and rpm to change impeller material and that's it . Any person with common sense can figure out that a heavier material will take more force to spin it and keep it spinning .
You could not be more incorrect.... Not being a douche, I do this for a living........
The impeller cavity is FULL OF WATER...... The weight is nearly completely irrelevant... So I guess common sense isn't all that common.
GT
Post by: GT Jets on August 04, 2017, 09:23:09 PM
The chart references at what hp and rpm to change impeller material and that's it . Any person with common sense can figure out that a heavier material will take more force to spin it and keep it spinning .
You are confusing "inertia" with "rotational force".
So what you're telling me, is that if I built a pump with a titanium impeller, impeller shaft and used an aluminum flywheel and no balancer but an aluminum hub, I'll pick up more RPM? Is that your argument?
It will rev quicker, but wont turn more RPM.... Fact.
Now I set forth the same challenge you did to me. What proof do you have that the material of the impeller changes the RPM cut for cut? And common sense wont fly. ;D
GT
Post by: GT Jets on August 05, 2017, 10:50:45 AM
The chart references at what hp and rpm to change impeller material and that's it .
So why then does the curve not deviate when the stainless or mag bronze is recommended? Wouldn't if offset?
Any person with common sense can figure out that a heavier material will take more force to spin it and keep it spinning .Won't take "more force", force is indicating torque, torque times speed is HP, it will take longer to get to the max rpm when heavier, but will take less force to sustain the max rpm. HP for HP and cut for cut, the top RPM will be theoretically identical.. The only disclaimer stated is that no two impellers are identical, so there could be a few RPM lost or gained here and there, but the tach in the dash probably wont indicate it...
If I'm wrong, you need to show me...
Meanwhile, I'm done.... And I'm not being a dick, just trying to educate, you challenged me to..... :thumbup:
GT
Post by: driller41 on August 05, 2017, 11:19:35 AM
I
Just to chime in on the aluminum vs stainless impeller discussion: the difference in horsepower required by the change in mass moment of inertia, is negligible. Due to the geometry, one can assume it's a cylinder, which would scale the inertia by 3 ish times. However, my gut says the difference in horsepower required is less than a horse power, thus the difference in weight will never be noticed. There are other variables that have way greater influence.
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Post by: connorstexas on August 05, 2017, 03:38:28 PM
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Post by: mach1_557 on August 05, 2017, 05:19:20 PM
Just to ensure the horse really is dead.... ;D
So why then does the curve not deviate when the stainless or mag bronze is recommended? Wouldn't if offset?
Won't take "more force", force is indicating torque, torque times speed is HP, it will take longer to get to the max rpm when heavier, but will take less force to sustain the max rpm. HP for HP and cut for cut, the top RPM will be theoretically identical.. The only disclaimer stated is that no two impellers are identical, so there could be a few RPM lost or gained here and there, but the tach in the dash probably wont indicate it...
If I'm wrong, you need to show me...
Meanwhile, I'm done.... And I'm not being a dick, just trying to educate, you challenged me to..... :thumbup:
GT
Here's the deal ,I've changed impellers at the river during the same day with the same boat the same engine and the pump setup within .002-.005 of the two different impellers and the stainless one spun 150 less rpm. The temperature was relatively the same because it was in February. So you telling me I'm wrong isn't going to change the data that came from changing the two impellers. Go ahead and pick it apart.
Post by: GT Jets on August 05, 2017, 05:47:19 PM
Here's the deal ,I've changed impellers at the river during the same day with the same boat the same engine and the pump setup within .002-.005 of the two different impellers and the stainless one spun 150 less rpm. The temperature was relatively the same because it was in February. So you telling me I'm wrong isn't going to change the data that came from changing the two impellers. Go ahead and pick it apart.
It had zero to do with the weight of the impeller........ Zero. I don't have to tell you you're wrong anymore, physics and my sharing an impeller chart should have shown you that.
If you changed impellers and the only thing different was the material (so you say) and you lost 150rpm, you simply had a different impeller, maybe the aluminum was cavitation burned and the SS was not.... I have changed HUNDREDS of impellers and I use an aluminum to get a baseline when going to a stainless because a stainless is a bitch to cut. They are normally SPOT ON.
I think I need to let you know that this is all I did for fifteen+ years....
GT