I have a question

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
pirate
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I have a question

Postby pirate » Sun Jan 15, 2017 6:56 pm

From time to time I see Lycoming O-320 engines that were originally straight valve 160 hp engines advertised as 170 hp due to the addition of angle valve cylinders. If angle valve cylinders automatically give a 10 hp increase why do most O-540 racing engines run straight valves when they could pick up additional hp just by switching to angle valves? If they add 10 hp on a 4 cylinder, that's 2.5 hp per cylinder. Does that mean they would add 15 hp on a 6 cylinder? I understand about power to weight but surely angle valve cylinders don't weigh that much more than straight valve cylinders to the point that they would negate a 15 hp increase. :scratch:
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Re: I have a question

Postby pirate » Mon Feb 20, 2017 5:34 pm

241 views....no replies, post, or opinions??
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mojoe
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Re: I have a question

Postby mojoe » Mon Feb 20, 2017 5:45 pm

So I am not a racer, nor am I an engine builder, but I have talked to somebody that built one of the fastest boats I know of and it is a SV 0-540. Bone stock internals (except for a mild grind on the cam). To my understanding, with the forced air intake and nitrous he was running it was too unstable to upgrade pistons or anything else internal. The EFI and electronic ignition worked together to keep it from blowing apart. There was no need for more power.

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Re: I have a question

Postby pirate » Mon Feb 20, 2017 7:59 pm

That's fine but what does that have to do with the questions I asked??
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mojoe
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Re: I have a question

Postby mojoe » Mon Feb 20, 2017 9:40 pm

1) I am trying to help you keep a dead thread alive.

2) I gave that example to explain my understanding of how one man made a damn fast 0-540 without changing pistons or valves.

3) I do not know why he did it that way instead of swapping to angle valves. Only that it worked.

4) With any luck at all, someone will correct my misinformation and you will have the answer you are looking for. Good luck!

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Re: I have a question

Postby Gary S » Tue Feb 21, 2017 6:00 am

I believe the angle valve cylinders raise compression. That said there are other ways to get there. There has been horse power numbers thrown out for years. But most of them are only numbers. Most the air boaters I grew up with didn't have the money to go out and buy a new motor, so they were put together with what could be had cheap. Some of the Frankensteins worked out better than others. Putting 0360 rods in 0320 was the thing to do for a while. But pistons are easy to get at a reasonable price that do the same thing.

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Re: I have a question

Postby John Fenner » Tue Feb 21, 2017 12:21 pm

Putting angle valve cylinders does help with flow to a certain extent, however they are heavier as well as the pistons, a true 170 hp crankshaft is as rare as hens' teeth, it has a longer stroke than an o320 but also has larger prop dowels, angle valve cylinders on an o360 will not equate to a true 170 hp 4cyl.
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Re: I have a question

Postby pirate » Tue Feb 21, 2017 12:32 pm

]Mojoe wrote
I am trying to help you keep a dead thread alive.


Thanks, I appreciate that. Just didn't quite answer my question.

Gary S wrote.
......There has been horse power numbers thrown out for years. But most of them are only numbers. ....
:thumbup:

I understand that there is more than one way to increase HP. I also understand that anybody building a go fast engine will increase HP however possible, within reason. A 10 HP increase on a four cylinder engine or 15 HP on a six cylinder by simply bolting on a cylinder of a different configuration after any other mods would be one he!! of an increase. Not sure it works that way.
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Re: I have a question

Postby pirate » Tue Feb 21, 2017 12:34 pm

Thank you John!
Compromise is failure on the installment plan.

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Re: I have a question

Postby pirate » Tue Feb 21, 2017 3:17 pm

John,

I've seen two true 170 HP (O-340) engines . Bore 5.1250 Stroke 4.125

Lew Ingle from Inverness owned both. To the best of my knowledge he still had one in his shop when he passed away. I probably have a copy of a parts catalogue for one around here somewhere if you need one.
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Re: I have a question

Postby John Fenner » Tue Feb 21, 2017 10:06 pm

pirate wrote:John,

I've seen two true 170 HP (O-340) engines . Bore 5.1250 Stroke 4.125

Lew Ingle from Inverness owned both. To the best of my knowledge he still had one in his shop when he passed away. I probably have a copy of a parts catalogue for one around here somewhere if you need one.

Thank you very much but no real need for it, my racing days left years ago, Don Davis and I had fun building and tuning for racing with major mods to Engines and such, I am into building custom one off builds or hulls at this point of time.
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