Need help with 454

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nebraskaairboater
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Re: Need help with 454

Post by nebraskaairboater » Thu May 10, 2018 9:47 am

Try the 2.3 in the belt drive to see if that helps. I run a 3 blade S 80" with my mild 472 Caddy with a 2.12 reduction. Set on 1.5 ish turning 4200 on engine. I just had a cam in a basically stock engine with a shaft rocker setup. I can't imagine my HP would have been more than your 425hp BBC.
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Re: Need help with 454

Post by ak375hh » Thu May 10, 2018 10:01 am

nebraskaairboater wrote:Try the 2.3 in the belt drive to see if that helps. I run a 3 blade S 80" with my mild 472 Caddy with a 2.12 reduction. Set on 1.5 ish turning 4200 on engine. I just had a cam in a basically stock engine with a shaft rocker setup. I can't imagine my HP would have been more than your 425hp BBC.

I thought it was a 425 454 when i bought the boat. I’m doubting it at this point. That’s why I’m looking into what I have to change

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Re: Need help with 454

Post by Joe » Thu May 10, 2018 12:50 pm

For the stroker kit look at skip white performance. I used one of there 383 kits for a buddy last year and it's a damn nice kit!! I wouldn't hesitate to get another one of there kits again!! He sells aluminum heads and pretty much everything you will need at good prices. For the cam call comp cams and talk with them. Be prepared to answer alot of question and you'll need your specs like compression ratio,what piston type and a whole lot more.

What 454 do you Have? Is it a mk4 5 0r 6? If a 5 or 6 get a set of stock vortex heads and have good 1 peice valves put in and springs to match your cam flat top pistons and an edlebrock airgap intake with a custom cam and you'll be right around 500hp. You should be able to do this for around 4-5k if you can put it together yourself.
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Re: Need help with 454

Post by ak375hh » Thu May 10, 2018 3:43 pm

Joe wrote:For the stroker kit look at skip white performance. I used one of there 383 kits for a buddy last year and it's a damn nice kit!! I wouldn't hesitate to get another one of there kits again!! He sells aluminum heads and pretty much everything you will need at good prices. For the cam call comp cams and talk with them. Be prepared to answer alot of question and you'll need your specs like compression ratio,what piston type and a whole lot more.

What 454 do you Have? Is it a mk4 5 0r 6? If a 5 or 6 get a set of stock vortex heads and have good 1 peice valves put in and springs to match your cam flat top pistons and an edlebrock airgap intake with a custom cam and you'll be right around 500hp. You should be able to do this for around 4-5k if you can put it together yourself.
It is a 4. I have been looking at a top end with alum heads put together by a machine shop up here, a cam they’re claiming to have had ground for airboats before and an intake. They’re thinking I should be around 450. I would be doing install myself. Keeping the compression moderate for the shit gas we have up here. That is also an option, one thing making me stop and think on that is wondering if a new top end on a used bottom end is a great idea...

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Re: Need help with 454

Post by One Eyed Gator » Thu May 10, 2018 3:51 pm

Yes there are a few of the white performance pieces around my area all run great. They are a good source for parts as well.

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Re: Need help with 454

Post by needcoffee » Thu May 10, 2018 3:56 pm

If you're going to do all that buy a stroker kit for it with a forged balanced rotating assembly and don't look back. If you're in the Anchorage area take it to Alaska drag bike.

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Re: Need help with 454

Post by ak375hh » Thu May 10, 2018 7:41 pm

needcoffee wrote:If you're going to do all that buy a stroker kit for it with a forged balanced rotating assembly and don't look back. If you're in the Anchorage area take it to Alaska drag bike.
I’ve talked with them about that. It was like pulling teeth to get a quote. Had to repeatedly ask what it would cost to have them build a 496. I was thinking of doing this top end on my 454, then take another 454 block I have and put the stroker kit in that and come winter I can swap it over as it will be off season then.

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Re: Need help with 454

Post by Joe » Thu May 10, 2018 8:59 pm

I agree that forged cranks are better but there's nothing wrong with the scat cranks in there kits for the hp and rpm range he is trying to use. I'm running a stock steel gm crank with zero issues. It's a damn good kit,especially for the price, 1349.00. It comes with the crank rods weisco forged piston bearings rings flex plate and balncer.
No I don't work for them,I don't buy alot from them and this isn't me trying to be a sales man. Just passing on a good kit at a good price to some one looking for more hp. Don't forget, he's in Alaska so shipping is out r ageous compared to what we pay in the lower 48
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Re: Need help with 454

Post by Slidin Gator » Thu May 10, 2018 10:31 pm

ak375hh wrote:I thought it was a 425 454 when i bought the boat. I’m doubting it at this point. That’s why I’m looking into what I have to change
It probably does make 425 Hp, if you set it up to spin over 5,000 RPM.

At 3,0000 RPM you are probably making 270 Hp and perhaps 330 Hp at 3,500 RPM (right around peak torque of 500 Ft-Lbf). This is nowhere near max power, you have to spin that motor up to make power and you need gear to do that.
ak375hh wrote:I should also ad it spins 4800rpm wot this way. And the oil pressure is good 60 at idle and runs up to 80-90 while running. I guess what I’m wanting to know is this motor worth putting money into...
Go take the boat out with the new prop, I bet you find it ran better with the 78” Power Plus, the one you could spin at 4,800, close to max power on the motor.


You have an 18 foot boat with lots of moose to haul (I want to shoot one!). How much does your rig weigh fully loaded? I assume well north of 3,000 lbs. You need a 700+ Hp engine and a 4 blade super wide prop to make that rig dry. To get that Hp in the working range of a big block, you need a ton of torque, more than you will ever get out of a $15,000 stroked 454 build. My opinion is don’t waste your money on the 454 engine, stroked or not. Set your sights higher (more motor) and treat those 454’s as consumables until you get there!

To put it in perspective, here is what you have now and how you might be able to get the most out of it:
Assuming a 425 Hp engine set up, I refer to the link below as a reasonable guide:
• 425 Hp 454 should make max torque of about 500 Ft-Lbf around 3,500 RPM.
• 425 max power at 5,300 RPM.
• I’m going to guess that the motor is making 470 Ft-Lbf at 3,000 & 4200 RPM.
• For 425 Hp, engine Torque at 5,300 RPM is 421 Ft-Lbf.

http://www.chevrolet.com/performance/cr ... ock-454-ho

I am attaching calculations to cover the following rough estimates of what it will take to get all 425 Hp out of the engine, and most into the prop/air. This is all for comparison with the 80” you tested.

Pay note of the power factor of 3.2. This describes the relationship between Hp and Prop speed for a given pitch setting. HP = Khp * RPM^3.2. The nominal value is 3 for 2 blade paddle blades. I used 3.2 (vs. 3.0) to account for the higher drag of wider blades and the +1 blade count.

At maximum power, with the engine screaming, you could net about 300 lbs of added thrust, perhaps close to 1,400-1,500 lbs of thrust, vs. the 1,200 lbs I think you might be getting right now. I doubt you will find that 1,500 lbs of thrust is going to push your boat loaded like you want, which is why I say you need even more.

You would need the following gear ratios to hit 5,300 engine RPM and achieve maximum power with that 80" 3 blade:
3.06 for Prop on #2 Pitch setting
2.8 for Prop on #1 Pitch setting

I also estimate that you will get into the low 4K RPM range on the engine with a 2.3 ratio upgrade and the same prop on the #1 pitch setting. That should net you about half of the extra you could get at max power, or another 150 lbf of thrust. The #2 pitch would be lower, although this is where you ultimately need to be.

Gear ratios are available to 3.0, but it is not the best route, you would be throwing money away if you are going to upgrade the engine. You are already considering upgrades and you should be looking for major torque (or Hp) upgrade in the 4000-5000 RPM range. With higher torque in this range, the gear preference will decrease to the point that a 2.43 or maybe a 2.3 gear is optimum. But it won’t be with a stock 454 set up.

Kwan had a suggestion that you look at a 2 blade hub which would probably get you into the max power range on your present engine with the 2.3 ratio and a decent prop pitch (#2 ish). This would not be too expensive and would let you get the most out of what you have now with a 2.3 ratio. But, the vibration of wide 80” blades in a 2x configuration could be a real problem, particularly on a gear box, it will be sensitive to balance. 2 blades are more efficient vs. 3 blades, but it all has to hold together.

You could also shorten the blades, but this does not work if you want to add more motor (I cut it off 3 times and it is still too short!). You could also switch to your old prop and upgrade to the 2.3, you were close to max power before, more gear and some pitch tweaks would probably hit 5,300 RPM for max power.

You could also go with a supercharged set up, but you are looking for a lot even with that.

My best suggestion: Assuming the 2.3 gear change is cheap (pulley changes I believe) and you are looking for a major motor upgrade build motor, I would switch to the 2.3 ratio box, run the 3 blade 80” at the #1 pitch point and add a 100+ nitrous kit. That stuff is cheap torque and will let you spin the prop when you are in a jam. Just,…. you know…., be careful!!! It’s a whole other learning curve.

Just plan on getting that new stroker making BIG TORQUE numbers before you blow the present from hitting the button to much and have to haul that beast out. You might have to wait until summer to bring in a dozer to get it.
Attachments
454 Gear Selection.pdf
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I grew up thinking I-10 was the Mason Dixon line.
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Need help with 454

Post by akmike30 » Fri May 11, 2018 12:41 am

Order a 502 from skip white performance and have no worries about nothing you’ll have all torc and power to spin 4 s blades. I spec out one there motors this winter about 800 in shipping to Alaska and little over 10k for drop in motor.

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Re: Need help with 454

Post by SWAMPHUNTER45 » Fri May 11, 2018 6:30 am

Like has been said many times before do your homework and read all the old threads. A 2.37 or 2.55 ratio is usually your friend. If your staying with the 2.1 your gonna be leaving performance behind with 4 wide blades.

Look at the guys who do it every day with success and what power / ratio the use. No need to labor over this there are a few to clone.

My 2 cents from the swamp, enjoy the repower it is always fun putting on more power.

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Re: Need help with 454

Post by kwanjangnihm » Fri May 11, 2018 9:10 am

Did you test any other pitch settings with the 3 blade power shift setup? The blades look over pitched in the photo.
Remove pitch and run them at a higher rpm to get into a better HP range.
4800 / 2 = 2400
5000 / 2 = 2500
5200 / 2 = 2600
5400 / 2 = 2800

A 2 blade S at 80" will stomp a mudhole in the azz of that 3 blade power shift!! :thumbleft:
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Re: Need help with 454

Post by ak375hh » Fri May 11, 2018 2:01 pm

It’s possible I have access to a 2 blade hub to try as well, you really think that’ll do better than the 3 power shifts? Just seems like I never see any 2 blade boats running around.

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Re: Need help with 454

Post by Slidin Gator » Fri May 11, 2018 4:19 pm

I am positive that the 2 Blade will outperform the 3 blade set up with the S blades. Keeping the same 80" S blades in a 2 blade config. and switching to the 2.3 ratio should get you turning 4,800 RPM or more on the #1 pitch setting (I'm guessing 440 ft-lbf torque, could be more). Compare that directly against the Power Shift as it sits now. The ratio change is still required to get there. If the 2 blade hub shortens the prop any, that is probably a bonus in this application

For the Power Shift I caution that you need to confirm max RPM for that prop, I think it is 2,450 or less (right where it is set now). So you may not have any margin to take pitch out without a ratio change. The 2.3 ratio (probably with less pitch) is a better option for the power shift too as it would let you spin the motor more while keeping prop RPM in reason.

If the 2 blade hub is a loaner and the 2.3 change is low cost, I suggest you have several options to try out at minimal cost to see what works best for you. Any of these changes should make it run better than it does now. Realizing you have a belt drive, vibration is less of a concern vs. a gear-gear set up.
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Re: Need help with 454

Post by F0zzy2 » Sat May 12, 2018 12:46 am

If your looking to run ground just bit the bullet and upgrade to a big cubic inch motor, 4 S blades and a larger reduction. Our boats with cabs on them really cut down on air flow to the prop so we are at a disadvantage already. I farted around with power upgrades on a 454 with my boat for a few year before upgrading to my current 580, It was a huge difference. I also switched to a 3 blade set up last year thinking I would be able to get more push because I could get more pitch with my S blades but that was a mistake and I'm back to my 4 blade set up pitched at 2. Skip Olsen has been making boats run ground for years up in fairbanks, he's the nicest guy you will meet and loves helping people. His number is on here and FB look him up. Also be careful with 502's and crate motors that don't inconel exhaust, that's important to have on an airboat set up.
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Re: Need help with 454

Post by ak375hh » Sat May 12, 2018 4:06 pm

Just measured before taking the s blades off and they’re 82”

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Re: Need help with 454

Post by Slidin Gator » Sat May 12, 2018 6:47 pm

ak375hh wrote:Just measured before taking the s blades off and they’re 82”
That makes more sense for how much they are holding the motor down. But it does not change the RPM projections I gave since prop diameter (and gear efficiency) were not part of those formulas.
F0zzy2 wrote:If your looking to run ground just bit the bullet and upgrade to a big cubic inch motor, 4 S blades and a larger reduction.
X2 on what F0zzy2 says.

All the prop tweaks discussed are just optimizing what you have right now until you sort out a new engine (still advocating the nitrous). For the big boats you guys run, you really need to go big or go home and don’t stop at a 502 or 500 Hp. A rule of thumb that has been quoted on this site is a 4:1 ratio for thrust to Hp. But it is not a linear relationship. 4:1 is roughly true to about 250 Hp. Between 250 and 750 Hp, the curve is closer to 2:1. Each Hp addition beyond 250 Hp nets an additional 2 lbs of thrust.

Another good rule of thumb here is a 2:1 Thrust to weight ratio for running ground (assuming you have polymer on the hull??). This is fairly linear for all boat weights, but definitely varies for different hulls and hull treatments (poly, slick paint etc.). Multiply the ratios (2 X 2) and assume 4 lbs of boat and gear per Hp added beyond 250 Hp.

250 Hp can produce 1,000 lbs of thrust on the boat (I know of a tested boat that achieved this) and that will push 2000 lbs of boat and gear on ground well. Beyond that, assume 1 extra Hp will push 4 lbs of loaded boat. If you have 4,000 lbs (you need to get a good weight) of boat, gear people and moose to push, the additional 2,000 lbs requires an additional 500 Hp. The 4,000 lb set up needs 750 Hp +/- to go anywhere, haul it all. You can get away with less, but more is always better; no one will ever tell you they are glad they went with less! :dontknow: Keep in mind that you are looking for reliable power.

I am attaching a bunch of charts that covers this and compares different engine/gear options. Some are tweaked to max engine power, others are backed off peak Hp intentionally. What is your preference? A big bore stroker turning to the low 5,000’s (with power to spare) or a hot rodded 502 wound flat out? :scratch:
Attachments
LS Vs. Big Block Compare.pdf
(931.47 KiB) Downloaded 31 times
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Re: Need help with 454

Post by ak375hh » Tue Jun 05, 2018 12:36 pm

No surprise, I have another question. If the recommended prop rpm range is being reached why is engine RPM range important? why do people seem to think the prop cares what rpm the engine is spinning? As long as the prop has its speed with reasonable pitch, shouldn't it work?

Currently have ch3 torn down swapping to 2.3 btw.

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Re: Need help with 454

Post by Slidin Gator » Tue Jun 05, 2018 6:58 pm

The engine makes more Hp at higher speed, up to the point of peak Hp. If your prop and gear is holding the engine down on RPM, then you are not putting maximum power into the air. We are doing some guessing here on the performance curve of your engine, I have been assuming the curve in the Chevy crate motor link provided earlier, which shows peak Hp at 5,400 RPM. I believe that you are probably running a marine 454 and that Chevy crate engine curve should be a reasonable match.

You are limited on the Power Shift right now. Per Kwan's observation you are probably over pitched on that prop (where it is less efficient) and you are right at the max speed rating of the prop. So you really can't put any more power into that prop.

One last thing, every owner has to decide what max RPM they want to run their engine to. It is reasonable to back it down from the max Hp point to get better fuel consumption etc., but you do net less thrust.

Ask again if you are still confused, I'm trying to figure out the best way to explain this. :scratch:
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Re: Need help with 454

Post by ak375hh » Tue Jun 05, 2018 9:30 pm

To clarify what I meant. If a props rpm range Is say 1750-2250 like the whirlwind sw and your spinning the prop 2000 rpm in the middle of its pitch range, why does it matter if the motor has a 2:1 and is doing 4000 rpm or a 2.3 and doing 4600 or a 2.5 and doing 5000 rpm. The prop speed and pitch stays the same, so why does the engine rpm really matter as much as long as you have enough pitch and are in the “optimum” rpm range?

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Re: Need help with 454

Post by SWAMPHUNTER45 » Tue Jun 05, 2018 9:49 pm

My observations over the years have been that Whirlwind like to spin at the higher part of their recommended range fyi

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Re: Need help with 454

Post by ak375hh » Tue Jun 05, 2018 9:50 pm

SWAMPHUNTER45 wrote:My observations over the years have been that Whirlwind like to spin at the higher part of their recommended range fyi

I just used their rpm range as an example. My options are power plus, and s blades.

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Re: Need help with 454

Post by SWAMPHUNTER45 » Wed Jun 06, 2018 7:21 am

My experience is the S blades work on a big or heavy boat. The late model version with stiffeners' are my choice and they will function well at a lower rpm. With them you just put the pitch around mark 1.75 and see what you can get from your engine. Add a little pitch if you have the power if not take a hair out. They push very well at 1750 blade rpm pitched at 2 and if you can get more rpm it's even better.

They take huge power to turn up so when adding or taking out pitch it's small degrees of change

The objective is to match the blades sweet spot to the engines sweet spot thru the selection of the best gear ratio. Not all engines make power low so they need a lot of ratio to help them carry the load to their peak range where as a engine build with a powerful broad curve can use less gear and pull power easier thru the entire range.

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Re: Need help with 454

Post by kwanjangnihm » Wed Jun 06, 2018 7:45 am

in simple terms - take advantage of all the HP your motor has to offer - you'll wish you had that
50hp when you get into the sh*t! :thumbleft:

4000 ~ 400HP
4600 ~ 425HP
5000 ~ 450HP
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Re: Need help with 454

Post by digginfool » Wed Jun 06, 2018 8:28 am

ak375hh wrote:To clarify what I meant. If a props rpm range Is say 1750-2250 like the whirlwind sw and your spinning the prop 2000 rpm in the middle of its pitch range, why does it matter if the motor has a 2:1 and is doing 4000 rpm or a 2.3 and doing 4600 or a 2.5 and doing 5000 rpm. The prop speed and pitch stays the same, so why does the engine rpm really matter as much as long as you have enough pitch and are in the “optimum” rpm range?
Besides what Kwan said, the other issue is the gear reduction is a torque multiplier so even though the blades are spinning at the same RPM, at different engine speeds, you have more torque available to turn them with more pitch which should result in more thrust (unless you are already over-pitched with your PS prop as was suggested earlier). However, you would definitely be able to swing the S blades.
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