Worth the trouble

Automotive powered airboat discussion.
Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Mon Nov 05, 2018 1:27 pm

A local place that sells airboats
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

One Eyed Gator
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Re: Worth the trouble

Postby One Eyed Gator » Mon Nov 05, 2018 1:54 pm

Try any big truck store for the flex

diamondback0320
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Re: Worth the trouble

Postby diamondback0320 » Mon Nov 05, 2018 4:00 pm

well your getting ripped bud if their charging you that much..hamant is usually $ 11-12ft

hdsadey
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Re: Worth the trouble

Postby hdsadey » Mon Nov 05, 2018 5:50 pm

Summit racing is like $10/ft for stainless 3" from Walker.
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Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Mon Nov 05, 2018 8:48 pm

I was just gonna use my flex i had left over and hard pipe it out the back the boat i found somebody to buy my headers for what i paid for them. So I’ll just loose the shipping.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Slidin Gator
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Re: Worth the trouble

Postby Slidin Gator » Mon Nov 05, 2018 8:52 pm

I buy SST at Napa, as well as Summit. But for test and tune, go get cheap steel to compare options.

Also, I don't understand what your motor guy is telling you about the flooding, cam issue and final result from the header run prior to intake change? Are you saying that the long tubes generate too much back pressure for the cam, leading to it running rich (versus flooding)? Running rich would indicate that the exhaust is not flowing as well. If it can't flow as much air, it can't use as much fuel, or make as much power.

Long tubes have to be tuned for a motor and RPM range, otherwise they plug up the works. Are you running mufflers? Mufflers can hamper long tubes but help shorty's. Try shorty's with and without mufflers.

I bet you settle on the muffled shorty's, they will give you the best low end and should let you net the 100 or so RPM that you think the intake is giving you. Use this method to compare configs for low end:

SWAMPHUNTER45 wrote:Poor man method

Measure out a 40 yard stretch of dry ground.

Do timed runs varying pitch.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 5:30 am

It’s complicated. A guy i know that builds engines not airboat engines says that when he dynos a engine the exhaust can help or hurt depends what the length of the primaries are etc. and that in his experience longer primaries tend to make if run fat.

The guy that built my motor said that they are hurting me because they are not a tuned exhaust but I’m not about to pull the freshly built motor out my boat so they can charge me 1,000 to pull the motor dyno it and put it back in for a few extra hp.

So I’m just going to put my shorty headers back on for now.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

CarMotorBarge
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Re: Worth the trouble

Postby CarMotorBarge » Tue Nov 06, 2018 5:59 am

You don't need to pull the engine and put it on a dyno. The prop acts like a dyno. You need to install an AFR gauge and tune the carb to the correct AFR at different RPMs with the engine on the airboat. You can do all of this with the boat running on the trailer.
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Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 8:44 am

I understand what needs to be done i just don’t have the resources to do it.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

CarMotorBarge
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Re: Worth the trouble

Postby CarMotorBarge » Tue Nov 06, 2018 8:54 am

What do you think needs to be done?
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 9:00 am

The carb needs to be set to what ever style exhaust I’m running through out the rpm range.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 9:20 am

I’m just tired of getting different opinions. Everywhere i look one guy will
Say long tubes are better for the bottom end and then here comes another guy and say short tubes are better for low end. And they will do the same thing on the other end say Longs a better for top end and then another guy will say short are better for the big end. All i know is i lost 100-200 rpms putting the long tubes one and it sounded lazy.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Slidin Gator
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Re: Worth the trouble

Postby Slidin Gator » Tue Nov 06, 2018 10:46 am

As stated originally, if the headers are not tuned to match the motor and RPM range, they will decrease performance.

The old saying is that Long Tube headers make torque, which they do, but only in the RPM range that they are tuned for. People confuse the statement about making torque to imply that they make torque at the low end. Tuning is part science and part art with the length of the primary tube being ONE of the key drivers in the RPM range that the headers are tuned for. The goal of long tube's is to make the primary long enough to time the pressure wave to hit the collector and then the inverse (suction wave) to flow back up the primary and hit the exhaust valve when open. This helps evacuate the cylinders and improve flow.

So, consider the time element, the lower the RPM range, the longer the primary tube needs to be in order to accomplish this timing trick. The problem is that you need really long headers to match the low end needs (3,000-4,000 RPM in this case) and tuning them for 5,000 will wipe out torque at 3,000. Those extra long primary headers can be fit into a car, but you would have miles of pipe wrapped around the motor in an airboat application.

Nascar uses long tube headers, they are tuned for the 8,000 RPM's those motors turn and the tubes are not all that long. They make torque at the RPM range those cars run.

I think this link and graphic is as good of an explanation as any:
http://garage.grumpysperformance.com/index.php?threads/calculating-header-design.185/
Image

That link includes links to header calculators. Take a tape measure to the headers you have and plug in the numbers. I'm just guessing here, but unless they are really long you will probably find out that they are tuned for higher RPM than you are running.

So, as a general rule shorty headers provide better all around performance over a wider RPM range, and they are always the better choice vs. an improperly matched set of long tubes. Further, resonating mufflers will improve performance with shorty headers vs. open pipes. A little bit of back pressure is good.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 11:30 am

So just put the short ones back on cause it clearly ran better with them and now that i have the intake on I’ll prolly gain my rpms back and then some
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Slidin Gator
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Re: Worth the trouble

Postby Slidin Gator » Tue Nov 06, 2018 2:27 pm

10-4, the thread is titled "Worth The Trouble", sounds like the intake is a yes but the headers are a no (going to be too much trouble).

Once you try it with the original exhaust on, then take some pitch out and test up to the 5,500 RPM rating of the intake. You will gain more low end response. Top end thrust may go up or down depending on where peak HP lies with the new intake.

I get the simplicity of straight pipes, but if you feel like fiddling in the future, try some mufflers. You should not loose and you may gain, either way your ears will thank you.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 2:55 pm

Seems like i hit the nail on the head with this thread title
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Tue Nov 06, 2018 3:06 pm

At 5500 im gonna be. Way over what the prop is rarer for.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Slidin Gator
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Re: Worth the trouble

Postby Slidin Gator » Tue Nov 06, 2018 4:17 pm

You are right, forgot about the 2:1 ratio, definitely don't want to over spin and throw away the gain!

Good thing you found a buyer for the pipes, makes that part of the experiment lower cost.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

One Eyed Gator
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Re: Worth the trouble

Postby One Eyed Gator » Wed Nov 07, 2018 9:00 am

For tuning if you have bung holes in your headers an AFR meter is around 200-250.00. As far as tuning it will let you dial in the motor where you want it. If you're into getting ever little bit you can out of the motor it is a great tool, no more guess work or peoples opinion as to motor being rich or lead.

The biggest change I made was going from a 2.0 ratio drive with a 2 blade 81.5" R to a 2.68 3 bld 79" Ron the same motor. It was an expensive change but in the long run for carrying weight on a fishing trip it was well worth it. It was like having a completely different boat.

Not sure of the belt drive but can you up grade the gear to a 2.3 that would put you in a better rpm range for your prop.

BTW I am the same as far as getting everything you can out of your current setup, I have been inching my way forward from a DD caddy for over 10 years to a 5.3 with a 2.0 then a 2.68 and just recently a mild 6.0 and 2.68 with a 3 bld.

Had a lot of help from my buddy smuggler a long the way. Many thanks to him.

just my 2 cents

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Wed Nov 07, 2018 12:09 pm

I wish it would let me post a video in here the boat runs. im Just being greedy.

Still undecided if i should put short ones on or not.

I don’t have room to put a bung hole for a gauge the collector is covered by the exhaust clamp.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Wed Nov 07, 2018 12:11 pm

It’s not like it’s a turd i can climb a. 20-30ft levee at thats at like a 45 degree with 3 ppl with 3 ppl i gota hjt it at kinda a angle but by my self and with another person i can climb it straight up no problems.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Re: Worth the trouble

Postby Basin_Runner355 » Mon Nov 12, 2018 5:35 am

Well i found out my problem why i lost power found somebody with a wide band O2 sensors it’s way to lean Glad i checked it cause it wouldn’t have lasted to long.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

Basin_Runner355
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Posts: 166
Joined: Sun Nov 13, 2016 7:16 am
Location: St.martinville , Louisiana

Re: Worth the trouble

Postby Basin_Runner355 » Mon Nov 12, 2018 5:36 am

Well i found out my problem why i lost power found somebody with a wide band O2 sensors it’s way to lean Glad i checked it cause it wouldn’t have lasted to long.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Slidin Gator
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Re: Worth the trouble

Postby Slidin Gator » Mon Nov 12, 2018 2:48 pm

Lean condition says that flow is improved vs. original tune, so it should give more power. Have you managed to tune it in now? What did you find for results?
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

Basin_Runner355
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Posts: 166
Joined: Sun Nov 13, 2016 7:16 am
Location: St.martinville , Louisiana

Re: Worth the trouble

Postby Basin_Runner355 » Mon Nov 12, 2018 5:45 pm

My afr was way out at like 16 so we went up 2 sizes in the front and 3 in the back gained 250 rpms. Ima have to get with my buddy to check it again but it deff gains some power of it wasabt for the safety chain it would want to climb over the trailer and it was strapped in the back.
14ft diamond back mild zz4 355sbc pushin 410 hp 430 TQ 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200


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