Need more power, not sure which route to take

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RedfireSVT
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Need more power, not sure which route to take

Postby RedfireSVT » Thu Jan 19, 2017 7:33 pm

Here's what I have, my boat is a 16ft Longhorn custom with a Gen IV 6.0L LS motor with a 2.3-1 belt and a 3 blade wide whisper tip prop. It runs well and will run dry but it can't climb a dirt boat ramp which is a big hassle. Not sure what the engine makes now, probably somewhere around 375-400hp but I'd like to get this thing to about 500-550hp. I'm not sure of the best way to get there and I would prefer naturally aspirated but can it be done with a cam and other modifications? The other two options are a roots type supercharger, Magnuson and Edelbrock both make kits but they are expensive, or I could put a turbo on it which sounds like a headache. Does anyone have any suggestions or advice?
16x8' 2014 Longhorn Custom
6.0L LS Motor
80" 3 Blade Whispertip
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Re: Need more power, not sure which route to take

Postby Basin_Runner355 » Thu Jan 19, 2017 7:51 pm

I'm no mechanic or expert but I don't see why you couldn't get those numbers. With the right parts in there they got plenty of ppl around my area pushing 500+ out of small. Blocks what ever you do get the best valve train set up you can
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Re: Need more power, not sure which route to take

Postby Basin_Runner355 » Thu Jan 19, 2017 7:52 pm

I have a zz4 350 on a 14ft diamond back and I can climb the bank and run the ground with 3 ppl with a 2 blade pretty easily
14ft diamond back zz4 355sbc 2:1 belt drive reduction with a 78 water walker falcons pitched at 5200

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Re: Need more power, not sure which route to take

Postby RedfireSVT » Thu Jan 19, 2017 7:55 pm

with my bowfishing setup and batteries etc my boat is heavy for a 16ft.
16x8' 2014 Longhorn Custom
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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Fri Jan 20, 2017 5:18 am

How much are you willing to spend? Is it fuel injected already? How many RPMs are you turning the engine at WOT? Have you upgraded the cam? Which 6.0 is it?
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Re: Need more power, not sure which route to take

Postby jeepinocala1111 » Fri Jan 20, 2017 7:00 am

Why don't you first go to a 4 blade and a 2.68 gearbox.

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Re: Need more power, not sure which route to take

Postby RedfireSVT » Fri Jan 20, 2017 8:54 am

CarMotorBarge wrote:How much are you willing to spend? Is it fuel injected already? How many RPMs are you turning the engine at WOT? Have you upgraded the cam? Which 6.0 is it?


I'd spend $3-$6k. Yes it's fuel injected. 5400rpms at wot. The cam is stock. It's a Gen IV 2011 and up 6.0L
16x8' 2014 Longhorn Custom
6.0L LS Motor
80" 3 Blade Whispertip
Love it!

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RedfireSVT
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Re: Need more power, not sure which route to take

Postby RedfireSVT » Fri Jan 20, 2017 8:55 am

jeepinocala1111 wrote:Why don't you first go to a 4 blade and a 2.68 gearbox.

I don't think it makes enough power to spin a 4 blade even with that reduction unit.
16x8' 2014 Longhorn Custom
6.0L LS Motor
80" 3 Blade Whispertip
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Re: Need more power, not sure which route to take

Postby Deano » Fri Jan 20, 2017 9:39 am

I have to agree, 375/400 hp is not nearly enough to justify the need or the expense of 4 blades and/or more gear.

While it's true that a gearbox is a 'torque multiplier' as Dave says, the difference between those options only amounts to a fat sixteen percent more torque. And as BBF points out, what you need is HP. Throw in the increased parasitic drag and weight of an additional blade/different hub and the only noteworthy difference you will see, would be in your bank account.

When considering HP, gear and prop, the thing you are lacking is Horsepower.
Put 500+ in front of what you already have box and prop wise, and you would
see a noteworthy difference that would justify the expense and make you smile.

You initially reported that it ran well earlier on. There is no escaping the reality of the power to weight ratio. If you've added floorboards, T-bars and 1/2" poly since then, it stands to reason you need to more power to offset the weight of your improvements over time.

IMO, there is no question that you are definitely on the right sheet of music.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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Re: Need more power, not sure which route to take

Postby jeepinocala1111 » Fri Jan 20, 2017 10:08 am

RedfireSVT wrote:
jeepinocala1111 wrote:Why don't you first go to a 4 blade and a 2.68 gearbox.

I don't think it makes enough power to spin a 4 blade even with that reduction unit.


What I was getting at was that large of a boat the gear change and prop change then more power I think he is going to need all three for that large of a boat to do what he wants.

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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Sat Jan 21, 2017 2:23 am

RedfireSVT wrote:
CarMotorBarge wrote:How much are you willing to spend? Is it fuel injected already? How many RPMs are you turning the engine at WOT? Have you upgraded the cam? Which 6.0 is it?


I'd spend $3-$6k. Yes it's fuel injected. 5400rpms at wot. The cam is stock. It's a Gen IV 2011 and up 6.0L


Oh snap. If it is a cast iron block, you probably have the L96 engine. You can verify this by looking at the GM part number on the block. This is a good engine because stock it has the L92 heads from GM. You need to get the 3 digit number off the corner of the heads and verify for sure which heads they are. The L92 heads flow approximately 314 CFM from the factory. The LS3/L92 castings are what WT Dave uses on his engines including his 600 HSP 418.

I have a couple more questions:

1. Have you done any upgrades to the stock engne?

2. Which EFI are you using? Is it the factory EFI?

3. Which intake manifold and mouthpiece are you using?

4. Is the throttle cable or DBW?

5. What are you pitched at on your prop now?

The cheaper route for upgrading is to put a more aggressive cam, double valve springs, and upgraded valves. Comp Cams or any other cam manufacturer can provide recommendations and pricing for this. They should also be able to tell you how much HSP you will gain. You will need an EFI tune done. You also need to verify the injectors are large enough. I would ballpark this upgrade at $1,500. LS motors respond really well to a cam upgrade.

Assuming you have the stock truck intake manifold and mouthpiece, you could also upgrade the intake manifold and mouthpiece. WT Dave is using an LS3 intake (250$) and a 92mm mouthpiece (around $400) on his 600 HSP 418 motors. You could also upgrade to the FAST aftermarket intake manifolds, but they are pricey (over $850).

If this doesn't provide enough HSP, the next step is to stroke the engine. The stroker kit will cost you around $2,000 to $2,500. The 550 HSP engines built by WT Dave are stroked LS2 blocks. The LS2 is a 6.0 block from the factory. The stroker kit will contain forged pistons and rods. This is a good upgrade over the factory pistons and rods. The factory pistons and rods are the weakest link in a factory LS.

You could also look into porting the heads you have. Texas Speed has some really good prices for CNC porting. They can also do spring and valve upgrades at the same time.

All of the price estimates above are for parts only. If you can't do the work yourself, I would recommend talking to a local engine builder.

After you upgrade the HSP on the engine, the next step is to upgrade the prop. You either need to add length to the prop or add another blade. Talk to Patti about this, but the cheapest route will be buying a longer 3 blade hub. I am assuming that you have enough room for a longer prop.

Hope this info helps. The LS engines are a great airboat engine when done right. 8) Why would anybody want an A/C engine? :stirpot: :stirpot: :stirpot: :stirpot: :stirpot: :stirpot:
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.68 Rotator soft drive swinging 4 blade 83.5" R
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Re: Need more power, not sure which route to take

Postby RedfireSVT » Sat Jan 21, 2017 9:03 pm

Yep, it is the L96 engine

1. Stock engine
2. Factory EFI
3.Stock truck manifold
4.Drive by wire
5.I'd have to look but Ty adjusted the pitch and tuned it.
16x8' 2014 Longhorn Custom
6.0L LS Motor
80" 3 Blade Whispertip
Love it!

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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Sun Jan 22, 2017 9:16 am

Here is a link to Texas Speed for ported L92 heads and cam package:

http://www.texas-speed.com/p-1170-precision-race-components-ported-ls3l92-heads-cam-package.aspx

This price includes a new set of heads. So the price will be cheaper since you already have heads. My suggestion is to call them and tell them what you currently have and want your HSP goal is. I would ask about doing a valve upgrade. Also you need to be honest with them about how many RPMs you are going to run this motor at WOT. Personally I would get the cam that made maximum HSP between 5600 to 5800 RPMs based on the prop and belt ratio. Also keep in mind that if you stroke this motor down the road, you will probably have to get a larger cam. Also are you currently running the knock sensors? The stock LS pistons don't like detonation. The knock sensors are cheap insurance to help prevent this. Hope this helps.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.68 Rotator soft drive swinging 4 blade 83.5" R
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Re: Need more power, not sure which route to take

Postby RedfireSVT » Sun Jan 22, 2017 12:16 pm

CarMotorBarge wrote:Here is a link to Texas Speed for ported L92 heads and cam package:

http://www.texas-speed.com/p-1170-precision-race-components-ported-ls3l92-heads-cam-package.aspx

This price includes a new set of heads. So the price will be cheaper since you already have heads. My suggestion is to call them and tell them what you currently have and want your HSP goal is. I would ask about doing a valve upgrade. Also you need to be honest with them about how many RPMs you are going to run this motor at WOT. Personally I would get the cam that made maximum HSP between 5600 to 5800 RPMs based on the prop and belt ratio. Also keep in mind that if you stroke this motor down the road, you will probably have to get a larger cam. Also are you currently running the knock sensors? The stock LS pistons don't like detonation. The knock sensors are cheap insurance to help prevent this. Hope this helps.


Thanks for the link. I think at this point I will start with a cam and getting my current heads ported and see what that does for the motor. I assume I will need to upgrade injectors and pump as well?

I have no idea about the knock sensors, how would I be able to validate if I have those?
16x8' 2014 Longhorn Custom
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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Sun Jan 22, 2017 2:23 pm

I am not sure whether you will have to upgrade the injectors and pump. Ask Texas Speed. They should know based on the cam selection. A lot of guys are upgrading the cam in their car and not upgrading the fuel injectors or pump.

The knock sensors are the black sensors on the side of the block just above the oil pan. You will have one on the starboard side and another one on the port side. You can google Gen 4 LS knock sensors and get tons of pictures.
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Re: Need more power, not sure which route to take

Postby jopete » Sun Jan 22, 2017 6:06 pm

before u go spend a ton of money, have u tried tuning your hull?
a couple sets of hull jacks will make a pig of a hull run the ground like a mofo.

I know putting some round in my hull made me go from hating it to loving it. and it was a lot cheaper than throwing money into the engine.

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Re: Need more power, not sure which route to take

Postby nebraskaairboater » Mon Jan 23, 2017 5:36 pm

if it runs the ground fine when flat get a run at the ramp. I can run my 16 foot antique heavy boat with a caddy up a dirt ramp I just get behind my wake and ride it up the ramp. I'm not positive I'd make it from a stop at the bottom of the ramp but have never not made it up yet.
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Re: Need more power, not sure which route to take

Postby RedfireSVT » Mon Jan 23, 2017 11:33 pm

I may go with a stroker kit
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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Tue Jan 24, 2017 5:45 am

I like it. 8) There is a ton of data online about stroking an LS2. The LS2 is a generation 4 aluminum 6.0 block.

You will probably need to get larger injectors. I am using 48 lb injectors on my 419. You need to verify this, but you will probably want either 42 lb or 48 lb injectors depending on how much HSP you ultimately make. You will definitely need a retune.

Also here are the specs for my cam in my 419:

Gross Valve Lift Intake: .620
Gross Valve Lift Exhaust: .617
Duration at .050 Intake 235
Duration at .050 Exhaust 248
Lobe Separation 113.0

My cam is setup to make max HSP a little over 6,000 RPMs. I am spinning my motor at 5,900 on the water. I have a 3 blade R with the short hub and a 2.68 Rotator. Not saying this is the cam you need. Just giving you a data point to reference.
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Re: Need more power, not sure which route to take

Postby One Eyed Gator » Tue Jan 24, 2017 8:09 am

Do a little research on cams, to make decent power in an ls you do not need a high lift cam. GMPP offers to cams Hot Cam and ASA Cam that work with stock valve train and upgraded springs. ASA cam has a nice flat torque curve and Both cams are low lift around .525 but have a little more duration. Makes them a little easier on the valve train. ASA Kit from GM is around 500.00. Add LS7 lifter and hardened push rods Still under 1000.00. Add upgraded injectors, throttle body and a retune. While your changing cam add ported oil pump and new timing chain. I believe you would close to your hp and $$ goals. To upgrade the intake without spending a bunch I would look for I believe it is the 04 and up TBSS Truck intake.

Building something similar for my boat.

Option 2 would be do the LS3 square port head swap and find a rebuilt GM supercharger. Not hard to do but a completely different budget.

Just a few thoughts

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Re: Need more power, not sure which route to take

Postby RedfireSVT » Thu Jan 26, 2017 1:06 pm

One Eyed Gator wrote:Do a little research on cams, to make decent power in an ls you do not need a high lift cam. GMPP offers to cams Hot Cam and ASA Cam that work with stock valve train and upgraded springs. ASA cam has a nice flat torque curve and Both cams are low lift around .525 but have a little more duration. Makes them a little easier on the valve train. ASA Kit from GM is around 500.00. Add LS7 lifter and hardened push rods Still under 1000.00. Add upgraded injectors, throttle body and a retune. While your changing cam add ported oil pump and new timing chain. I believe you would close to your hp and $$ goals. To upgrade the intake without spending a bunch I would look for I believe it is the 04 and up TBSS Truck intake.

Building something similar for my boat.

Option 2 would be do the LS3 square port head swap and find a rebuilt GM supercharger. Not hard to do but a completely different budget.

Just a few thoughts


Thanks for the cam info! My motor is the Gen IV LY6/L96 engine so it already has the LS3 square port heads on it from the factory.
16x8' 2014 Longhorn Custom
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80" 3 Blade Whispertip
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Re: Need more power, not sure which route to take

Postby One Eyed Gator » Fri Jan 27, 2017 1:42 pm

There is a facebook page LSX parts for sale. There a number of stock GM supercharger on there for sale and you would want a supercharger cam.

If I didn't do the supercharger then it would be Cam, springs, pushrods, Injectors and a Tune. Maybe add the throttle body and Fast LSXRT intake.

Not sure if the ASA will work in the motor.

Good luck and report back with how your final upgrades turn out.

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Re: Need more power, not sure which route to take

Postby RedfireSVT » Sat Jan 28, 2017 11:09 am

I like those FAST intakes and 102mm throttle bodies but the gains don't really justify the cost. $1500 for 15hp might not be worth it unless there is a greater increase when combined with a cam. Having the heads ported was also something I've thought about having done. I'm looking at every option before I jump into this because it can get expensive quick. If I could find a good used supercharger that would be my first choice, if not then I think cam, valve train, intake, throttle body and a tune. If that doesn't get me the power I need then I'll do the 408 stroker kit with a new cam and tune. If that doesn't work I'm going to sell the boat.
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80" 3 Blade Whispertip
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Re: Need more power, not sure which route to take

Postby CarMotorBarge » Sun Jan 29, 2017 9:23 am

The FAST intakes are definitely expensive. Look at the LS3 stock intake manifold. You can get them new for $250 online all day long. Also get a 92mm FAST mouthpiece. I think these are around $400, but you need to check that price. This combination or a similar combination is what WT, MAST, TKE, etc. are using on their 550 and 600 HSP motors. It is much more cost effective than the 102mm FAST intake and throttle body. Also if you switch to a FAST or LS3 intake, I think you will have to get new fuel rails. I am assuming you are using the truck fuel rails and I don't think they will work.

You could also stick with the truck intake. Here is a recent article that compares 20 different LS intakes:

http://www.hotrod.com/articles/20-ls1-intake-manifolds-tested/

There is a ton of good data in this article. The truck intake definitely held its ground. They used a 6.0 engine with a big cam. I don't think you want a cam this big because you aren't going to be spinning the engine over 6000.

Another good upgrade to consider for dependability is a trunnion upgrade. They aren't that expensive and help improve the durability of the valve train. Also if you pull the heads, you might as well put LS7 lifters in. This is another good upgrade.

It is definitely a good idea to plan everything out. It can get expensive really quick, but it is only money. You can't take it with you. 8)
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.68 Rotator soft drive swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer
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Re: Need more power, not sure which route to take

Postby RedfireSVT » Sun Jan 29, 2017 12:48 pm

I read that article just yesterday, it made me want to stick with my truck intake and save the money. I'm not sure what size throttle body it has or how big the factory opening is on that intake, I assume a 90mm TB will work if I want to upgrade? I was also looking into having my heads ported, I have the good L92 heads and I wonder if there is a benefit, Texas Speed does it starting at $750.00 and I could also do all valvetrain upgrades. My motor only spins to 5200rpm max using a 3 blade wide Whispertip on a 2.3-1 reduction belt so I need to make all my torque between 3000 and 5000rpm, not interested in anything above 5000rpm. So really I've got it down to a cam, possibly a TB, possibly porting my heads and doing valvetrain upgrades and of course fuel system upgrades and I'll need a tune.

How can I determine the cam specs I would need for my setup? I already know I don't want a high lift cam.
16x8' 2014 Longhorn Custom
6.0L LS Motor
80" 3 Blade Whispertip
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