5.3 efi hamant

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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Re: 5.3 efi hamant

Post by hmgm123 » Mon Sep 22, 2014 8:36 pm

I think what Diggin is talking about is the cylinder head pressure. Putting more pitch on the motor raises the head pressure. Not saying that is the case with your motor. But is something to think about. Sounds like you got a good running boat.

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Re: 5.3 efi hamant

Post by josh_2562 » Mon Sep 22, 2014 8:41 pm

What ecm are you using? Im looking at building a turbo 4.8 to replace my 383

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Re: 5.3 efi hamant

Post by captain chad » Mon Sep 22, 2014 8:43 pm

I do like those EFI computer controlled and monitered engines but they arent always 100 percent on it.
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Re: 5.3 efi hamant

Post by ls1airboat » Mon Sep 22, 2014 8:46 pm

im running a stock 2002 gm ecm with a stock tune..btw a gm stock tune leaves alot of hp on the table..i left mine stock cause the boat runs anywhere i want.

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Re: 5.3 efi hamant

Post by ls1airboat » Mon Sep 22, 2014 8:52 pm

you can always plug in a hand held computer to the obd2 port and run it on live mode and see what its doing at all times.

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Re: 5.3 efi hamant

Post by digginfool » Mon Sep 22, 2014 11:00 pm

The ECM is very good about managing the engine in the parameters it was set up for but at the end of the day, it's only as smart as the program it's running. As sophisticated as it may seem, it really is only monitoring a few parameters; throttle position (driver's implied intentions), amount of air flowing in (mass air flow meter), amount of fuel going into the combustion chamber and amount of oxygen in the exhaust (is the engine rich or lean?). The engine uses the knock sensor to make sure the ignition is not being advanced too much. Ignition advance is what builds more pressure to accelerate the engine. When you push on the throttle, the ECM takes the amount of travel and how quickly it was pushed to assume the driver's intention. Ease the throttle down and the ECM will add fuel, advance ignition and monitor exhaust gases to optimize the power delivery. Mash on the pedal, and the ECM sets the parameters for maximum acceleration; it dumps fuel, advances ignition and looks for a rich exhaust gas to ensure it's doing the job it's being asked to do. The difference with an airboat is it is stuck in one gear. The transmission control for the ECM has been over-ridden. In an automotive application, if the ECM does not see the engine accelerating quickly enough for the amount of fuel being fed into the cylinders, it will tell the transmission to downshift to give the desired result which also helps prevent excessive combustion chamber pressures. We don't have that in an airboat. If you are telling the engine to give you full throttle (which it interprets as being 6,000 RPM) and the prop is holding it at 4,600 RPM, it will continue to give full fuel delivery and ignition advance until detonation is detected or limits are reached. It has no idea what the combustion chamber pressures are and will continue to deliver fuel as demanded. This is not a condition that will immediately destroy an engine (as long as the knock sensors are working properly) but will reduce the life of the engine. If you have a new motor and forged rotating assembly, this may not be as much of an issue (but the wear on your rings and cylinder walls, as well as rod and main bearings will be accelerated) but you are running a junkyard motor with a 100,000 miles on it and cast or hypereutectic pistons. You would be better served running the engine at a higher RPM where it was designed to provide maximum power. Remember, torque accelerates, horsepower holds. If your target propeller RPM is 2,300 (4,600/(2:1) box), it would be easier on your motor to achieve it with a 2.38:1 at 5,300 RPM. As I said in the beginning, lugging an engine can be just as detrimental as over-revving. A small block is designed to operate at a higher engine speed. It's where it develops its power, which is what maintains prop speed. Torque accelerates, horsepower holds. Hey, if it works for you and you really do just cruise all the time, you probably won't notice a difference. But if you are going out and trying to keep up with all your high HP buddies, you're putting unnecessary wear on your engine. Plus, with just a little less pitch, the boat will be much snappier, run a little faster and will most likely push just as well. There's a reason the LS guys are running 2.5 and 2.7 boxes with their motors and that is how they maximize power delivery and reliability.
Last edited by digginfool on Tue Sep 23, 2014 12:03 am, edited 1 time in total.
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Re: 5.3 efi hamant

Post by Bdriller » Mon Sep 22, 2014 11:19 pm

Better listen to digger he blew his up a week ago!

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Re: 5.3 efi hamant

Post by digginfool » Tue Sep 23, 2014 12:08 am

Bdriller wrote:Better listen to digger he blew his up a week ago!
Actually about a month ago. That had more to do with poor piston design than anything. The 8.1 is famous for shattered pistons. The top ring land was not thick enough and under heavy loads is known to crack leading to complete piston failure. That's precisely what happened to mine. This is a picture from a website that describes the failure and shows the land snapped off but prior to complete piston failure.
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Re: 5.3 efi hamant

Post by ls1airboat » Tue Sep 23, 2014 4:55 am

ill keep mine where its at...the boat is doing awesome...if it blows i already have the money put back for another one..like i said the motors are very cheap and lkq will bring it to my shop. hell i might buy one and put a zo6 cam in it and leave it on motor stand till i need it .

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Re: 5.3 efi hamant

Post by Jgamble » Tue Sep 23, 2014 6:31 am

Im glad everything is working out on your boat i hope that 3 blade R works good for you too. I know the metal works and the Q were junk on my end, So good luck

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Re: 5.3 efi hamant

Post by Bruce » Tue Sep 23, 2014 6:55 am

Yep diggin all that stuff sounds great in theory but hasnt proven to be true yet
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Re: 5.3 efi hamant

Post by HuntingBigun » Tue Sep 23, 2014 8:49 am

digginfool wrote:The ECM is very good about managing the engine in the parameters it was set up for but at the end of the day, it's only as smart as the program it's running. As sophisticated as it may seem, it really is only monitoring a few parameters;
You do like to type I give you credit shame that most of what you type is just not totally 100% correct, you had 8.1 its ECM is like comparing carb to fuel injection on the LS, you blew your shit up by having low oil pressure and boat on it side then running it at WOT because you were lost and scared I guess or just dumb a$$, most of us know not to do that in a aircraft or carmotor. You can dumb down a ECM but mine is not, but all you have to do is talk to the Engine Builders or builders of LS boats like Hammit, DB & Panther to get the correct info which last time I checked that is not your title Diggin 8) 8) 8) 8) to get correct info,

Dave never told me to run my engine waterthunder at high RPM 5500 max LS3 600 HP with all the goodies, my MAST LS7 ECM limited to 6000 and it also has all the goodies so in a AIRBOAT application with stock LS he better off NOT twisting guts out of his motor, GM did not design that engine to run at 5500 rpm for extended duration, matter of fact the 8.1 was not as well, that is why you pay more money for a airboat spefic engine than a crate motor. But beware if you stay at WOT for extended time. But Diggin should know already :violent1: :violent1: :violent1: :violent1:

Congrats on your boat LS1and just listen to Wade Hammit not all these internet experts that do not even own a LS just type BS they read on the net or someone told them. I swear we should have a block feature on SA so if you never owned a motor or hull it would shut up fools like Diggin but we have to have couple village idiots to laugh at 8) 8) 8) 8)
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Re: 5.3 efi hamant

Post by JT540 » Tue Sep 23, 2014 9:08 am

HuntingBigun wrote:
digginfool wrote:The ECM is very good about managing the engine in the parameters it was set up for but at the end of the day, it's only as smart as the program it's running. As sophisticated as it may seem, it really is only monitoring a few parameters;
You do like to type I give you credit shame that most of what you type is just not totally 100% correct, you had 8.1 its ECM is like comparing carb to fuel injection on the LS, you blew your **** up by having low oil pressure and boat on it side then running it at WOT because you were lost and scared I guess or just dumb a$$, most of us know not to do that in a aircraft or carmotor. You can dumb down a ECM but mine is not, but all you have to do is talk to the Engine Builders or builders of LS boats like Hammit, DB & Panther to get the correct info which last time I checked that is not your title Diggin 8) 8) 8) 8) to get correct info,

Dave never told me to run my engine waterthunder at high RPM 5500 max LS3 600 HP with all the goodies, my MAST LS7 ECM limited to 6000 and it also has all the goodies so in a AIRBOAT application with stock LS he better off NOT twisting guts out of his motor, GM did not design that engine to run at 5500 rpm for extended duration, matter of fact the 8.1 was not as well, that is why you pay more money for a airboat spefic engine than a crate motor. But beware if you stay at WOT for extended time. But Diggin should know already :violent1: :violent1: :violent1: :violent1:

Congrats on your boat LS1and just listen to Wade Hammit not all these internet experts that do not even own a LS just type BS they read on the net or someone told them. I swear we should have a block feature on SA so if you never owned a motor or hull it would shut up fools like Diggin but we have to have couple village idiots to laugh at 8) 8) 8) 8)
lol. damn wayne. so I guess what your saying is his screen name says it all!!! and I have the 5.3 in my trucks and when towing under load they really like about 2800 rpm that's when they seem to pull hardest so why would that be any different then putting a prop on and your cruise be in that range they are in there sweet spot for stock motor. now im not an ls expert but it seems like common sense to me!
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Re: 5.3 efi hamant

Post by ls1airboat » Tue Sep 23, 2014 9:23 am

the bottom line to this..its my boat.. i BUILT it.. i didnt buy it..it runs awesome to me and im not changing a damn thing until it comes apart..its not a high dollar engine its 600 bucks with 100k miles on it so it could come apart at anytime..and for the record i went everywhere the stroker motors went and didnt have to run it that hard...sometimes its more about set up than hp..... and ps.. and damn the boat is beautiful.

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Re: 5.3 efi hamant

Post by One Eyed Gator » Tue Sep 23, 2014 9:36 am

Hey post a few pics?

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Re: 5.3 efi hamant

Post by ls1airboat » Tue Sep 23, 2014 9:42 am

i guess some people just cant say good job and be proud of what ya built..im proud of what i built and and every damn bolt i put in.. and to me its just how i wanted it ..i dont give a rats ass about a/c..c/m..race boat or a piece of sht..ill be proud to ride with anyone on this site...and im the first one to help you out not put you down for what you have..hell i give parts to people to make there boats better..and ill sit on a island and work on boats of people that i dont even know just to get them going again...if you dont like me.. my boat,, or my set up..keep it to your self..remember not a dime came out of your pocket to pay for my build.

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Re: 5.3 efi hamant

Post by Bruce » Tue Sep 23, 2014 10:03 am

ls1airboat wrote:i guess some people just cant say good job and be proud of what ya built..im proud of what i built and and every damn bolt i put in.. and to me its just how i wanted it ..i dont give a rats ass about a/c..c/m..race boat or a piece of sht..ill be proud to ride with anyone on this site...and im the first one to help you out not put you down for what you have..hell i give parts to people to make there boats better..and ill sit on a island and work on boats of people that i dont even know just to get them going again...if you dont like me.. my boat,, or my set up..keep it to your self..remember not a dime came out of your pocket to pay for my build.
that says it all right there
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Re: 5.3 efi hamant

Post by Jgamble » Tue Sep 23, 2014 10:13 am

Ill step away from the croud and say I seen the boat in person in the build stage and it looked great for where it was at, And as far as everyone else i agree if you cant give good advice thats solid then you should keep your mouth closed my .02 no offence to anyone. Good job on the boat, bad judgement on my part. Alls good :)

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Re: 5.3 efi hamant

Post by Waterthunder » Tue Sep 23, 2014 10:30 am

ls1airboat I will tell you the better it runs the less likely it will be complemented. It actually goes the opposite way the better it runs the more negative comments you will hear. And as for advise from people on the internet all I can say is about every person I have meet or talked to in the last 2 years knows far more about LS engines than I ever will. So I have learned to just sit back act stupid and let people go in their own direction! Don't let any comments bother you if your looking for complements your doing things for the wrong reasons!

Not that it matters much but I feel you made the best choice for a welded hull!
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Re: 5.3 efi hamant

Post by digginfool » Tue Sep 23, 2014 10:38 am

HuntingBigun wrote:
digginfool wrote:The ECM is very good about managing the engine in the parameters it was set up for but at the end of the day, it's only as smart as the program it's running. As sophisticated as it may seem, it really is only monitoring a few parameters;
You do like to type I give you credit shame that most of what you type is just not totally 100% correct, you had 8.1 its ECM is like comparing carb to fuel injection on the LS, you blew your **** up by having low oil pressure and boat on it side then running it at WOT because you were lost and scared I guess or just dumb a$$, most of us know not to do that in a aircraft or carmotor. You can dumb down a ECM but mine is not, but all you have to do is talk to the Engine Builders or builders of LS boats like Hammit, DB & Panther to get the correct info which last time I checked that is not your title Diggin 8) 8) 8) 8) to get correct info,

Dave never told me to run my engine waterthunder at high RPM 5500 max LS3 600 HP with all the goodies, my MAST LS7 ECM limited to 6000 and it also has all the goodies so in a AIRBOAT application with stock LS he better off NOT twisting guts out of his motor, GM did not design that engine to run at 5500 rpm for extended duration, matter of fact the 8.1 was not as well, that is why you pay more money for a airboat spefic engine than a crate motor. But beware if you stay at WOT for extended time. But Diggin should know already :violent1: :violent1: :violent1: :violent1:

Congrats on your boat LS1and just listen to Wade Hammit not all these internet experts that do not even own a LS just type BS they read on the net or someone told them. I swear we should have a block feature on SA so if you never owned a motor or hull it would shut up fools like Diggin but we have to have couple village idiots to laugh at 8) 8) 8) 8)
Don't recall you being out there, Wayne, but I'm not going to re-hash that night. Don't claim to know it all and I've asked if any of the engine builders want to weigh in. I may be new to airboats but certainly not new to engines. As far as my motor, it was airboat specific. Came from Marine Power and installed by Diamondback when boat was new and prop was pitched for 5,100 RPM on the water, just as it was suggested to me. I put myself in a position where I had to run the engine very hard and I paid the price. That doesn't change the facts, though. The 8.1 piston issue is well documented and the failure in my engine was not oil related. In fact, it is directly related to what I'm talking about right here; combustion chamber pressures exceeding what the pistons could handle. For what it's worth, the oil pressure had dropped from the 60 - 65 psi it normally ran to around 45 - 50 psi. Ominous sign, no doubt, but I've completely disassembled the motor and there is absolutely no sign of oil starvation.

My question arose from the countless threads on here that list recommended target speeds for setting pitch and I don't recall ever seeing a small block being recommended for such a low speed through a box. Even Waterthunder advertises their engines as being able to turn a particular sized prop at 5,400 RPM as a measure of proof. So, what exactly is your point besides the top of your head, Wayne? Are you telling him your props were pitched for max RPMs of 5,500 and 6,000 RPM? Why do you think that is, Zippy? As far as the ECM goes, even with the latest, greatest iteration, it's not a do-all, save-all proposition. If you mistreat the motor, it will still fail. As I said, if he is just going to cruise around, I doubt he will ever have an issue and by all means, have fun doing so. But if he is going to go out and try to keep up with the high HP crowd, he may be better served taking some pitch out of the prop. His motor will be happier in the long run. Perhaps a true expert (as opposed to someone who married into it) on motors can weigh in. I'm always looking to educate myself. If you don't ask, you won't learn. If you don't share, you can't be shown your errors. In the end, you got to convince yourself.
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Re: 5.3 efi hamant

Post by digginfool » Tue Sep 23, 2014 10:49 am

ls1airboat wrote:the bottom line to this..its my boat.. i BUILT it.. i didnt buy it..it runs awesome to me and im not changing a damn thing until it comes apart..its not a high dollar engine its 600 bucks with 100k miles on it so it could come apart at anytime..and for the record i went everywhere the stroker motors went and didnt have to run it that hard...sometimes its more about set up than hp..... and ps.. and damn the boat is beautiful.

And my hat's off to you. I'm not beating down your build whatsoever. Just questioning whether or not the boat would perform better with less of a load on the motor. And also looking for someone that builds engines to either confirm what I'm saying or explain what is or isn't right. If you don't ask the questions that come to mind, you'll never get the answer.
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Re: 5.3 efi hamant

Post by wild-0540 » Tue Sep 23, 2014 11:04 am

hey matt we can put my solus pro on it and look at the engine calculated load at 4600 wot , then compare to a 1500 chevy at 4600 with a trailer heavy boat behind it in third gear , that will solve this whole issue. you will not detonate the engine or blow it . geeze . if you own a 1500 chevy and run 70 down the hwy it turns 1800 rpm or so. does anyone ever run there truck at 5400 everywhere they go ? ofcourse not!! so why harp on this rpm fact , in truth wot at 4600 only used 10% of time most time its cruising around in the water. like I said we can look at cal eng load fuel trim timing curve. and see if its struggling as everyone is soooooo fearful of. rolling my eyes....

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Re: 5.3 efi hamant

Post by Waterthunder » Tue Sep 23, 2014 11:37 am

Wild -540 that would not even come close to a equal comparison. A truck and a airboat load the engine differently.



Combustion pressures exceeding what a piston can handle. THAT IS THE DEFINITION OF DETONATION!

I'm sure the piston above could have handled reasonable combustion chamber pressures.

Airboat engines tend to put a heavier load on a engine, they tend to detonate and have higher cylinder pressure spikes, the only thing even close is a sled pull motor.

What detonation is and what happens under detonation is violent cylinder pressure spikes. These pressure spikes are what causes piston damage.
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Re: 5.3 efi hamant

Post by digginfool » Tue Sep 23, 2014 12:25 pm

Thanks for the clarification, Dave. But let me ask you this: Where is detonation most likely to occur; heavily loaded at lower RPM or at higher RPM?
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Re: 5.3 efi hamant

Post by Waterthunder » Tue Sep 23, 2014 12:55 pm

When the cylinder pressures are the highest. That can happen at either this is one of many reasons I prefer the 2.68 it is much easier on a engine over a 2 to1 ratio.


I hear many people say there is no difference between a car and a airboat, This is not true. A truck or car changes gears as the load changes. A airboat never changes gears.

The analogy I have used for 20 plus years is take a 1975 Chevy pick up with a manual transmission fill the bed with rocks and start of in 3rd gear that motor will detonate its self to death. As mentioned before someone suggested going down a highway in 3rd gear at the same RPM's with a load may be close to an airboat application but the entire time getting to that point is not even close.
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