Author Topic: 18hp Oppy running Alky (engine, intake and ignition)  (Read 7574 times)

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Offline Ace726

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18hp Oppy running Alky (engine, intake and ignition)
« on: February 28, 2017, 05:52:52 pm »
So I'm partway through building my oppy to run alcohol and I've found myself questioning some of the expenses on certain components if they are absolutely necessary.
First off im not going cheap on the build, I just want to be sure I'm justified in every expense. I already have the Arc rods, and Im ordering mod 28 pistons, wrist pins this friday. Arc billet flywheel is on the list. I am using an MSD ignition/coils with an Tillotson HL-360D Carb and custom intake (for the side draft conversion).
My questionable items are not so much major break points but more a question of performance. I'm on a bit of a time crunch as our test/tune track day is May 7th.  The biggest thing is the cam, I can see how much of an improvement the different lift would be but is it needed? has anyone every lobed or broke the stock cam? If I get a cam it'll be about 250 shipped and I'll end up reinforcing the rest of the valvetrain on it, I.E. bronze valve guides, Stainless valves stock size, stronger valve springs and billet keepers not to mention the addition machine cost if the heads need relief cuts. I believe the lift on the new cam would be around .360. I know it'll be a big power difference but how strong is the stock cam?

P.S. this is NOT just a cam thread, it's for the engine build. more questions to come as it progresses.
The Green Overtaker

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Offline redline

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #1 on: February 28, 2017, 08:02:15 pm »
The cam is the "brain" of the engine, as it allows air/fuel in and out and also determines when.
If your going all out on the engine, but letting it breathe with the stock cam, thats like putting a Geo Metro engine in a Ferrari.
This is in regard to engines in general, not the oppy, as anyone who knows me, knows I have no use for the boat anchor.
.360 lift? That's not much...What cam are you looking to get?
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Offline BIG AL 202

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #2 on: March 01, 2017, 08:06:24 am »
Alky? no organization I know of will let you run that. As for a cam people have had real good luck with the "rooster grind" from Isky cams.
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #3 on: March 01, 2017, 05:10:38 pm »
@redline I'm using the "boat anchor" because it's what I've got, I'd rather spend 2,500 on the entire machine than spend the same amount on a stock new engine and suddenly i've spent 5k on the build. As for the cam, I'm not looking to go more than .050 over stock lift (I thought stock lift was around .320) because as you know alcohol requires much more compression so I don't have much clearance on the heads to work with. I'm looking at a cam from Mike with precision cams.

@BIG AL There is an affiliated organization near me that uses the stabil rules as "guidelines" for their own, because of that they created their own class of Outlaws (we call it FX) where the tech rules are much more lenient on things like engine origin, fuel type, tire size/type and overall cubic centimeters (max 1000cc). The rooster grind is a lift of .410 which is too much for the high compression heads. As for Tim Isky, I've tried to get a hold of him multiple times to see what other grinds are available but no luck.
The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #4 on: March 01, 2017, 05:17:24 pm »
Here is the mower I started the build with, I built and ran it last season as a super mod (their version of FXT). season before that it was a modified.

www.heymow.com/index.php/topic,31256.0.html



The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

Offline BIG AL 202

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #5 on: March 01, 2017, 05:57:26 pm »
If you don't get the flow you are defeating the purpose of using alky. You will never get the compression ratio very high on a flathead. You will get your power from flow, and the cam gets the flow going! The cam has more going on other than lift.
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Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #6 on: March 01, 2017, 08:13:28 pm »
Ok, seems I've got more research to do. I will post more updates once I get more parts.
The Green Overtaker

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Offline berthyd

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #7 on: March 01, 2017, 08:17:31 pm »
Alcohol had about half the BTU content of gasoline, meaning theoretically you need to burn twice as much alky to equal the power of gasoline. Alky is generally used in racing because of its octane rating, around 110, and because it burns cooler.

Given the need to pass more alky through the engine compared to gasoline, one might assume a more aggressive cam would be necessary to achieve this result. Don't care what cam theory someone subscribes to (lift vs. duration), it's clear you need a reground cam.

Bert
Gary Busey and Rick James both used to live in my shop. Redline stole them.

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #8 on: March 01, 2017, 09:55:02 pm »
I've used alcohol in other engines before and it will take twice as much as gas with more than an equal power output. As in 20-30% more depending on the application and flow. Also there are other factors that can increase the flow of an engine than just a cam. That's the only reason I brought up the question, it WILL run on alky with the stock cam and run better than gas. It's just not optimized for alky, so considering that I'm getting a cam. Call it an insurance plan for that much more to the wheel......   assuming the drivetrain holds up  :omg:
The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

Offline PJG56

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #9 on: March 01, 2017, 11:38:49 pm »
So will this be one of those 60HP oppy's running on alcohol when done??
Paul Guptill  (oppy) #238modX
2012 slmra mowstock champion(builder/owner)

2013 slmra mowdified champion(builder/owner)
2013 ARMA national champion Mod-X(builder/owner)
2014 ARMA national champion Mod-X(builder/owner)
2014 All American Champion Mod-X/CP(builder/owner)
2014All American Champion FXT (engine builder)
2014 All American 2nd place SP(builder/owner)
2015 All American 2nd place BP (builder/owner)
2016 OutlawTriple Crown FXT Champion (engine builder)

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #10 on: March 02, 2017, 03:28:14 am »
I haven't decided yet lol the ignition setup I'm looking at to reach 9k rpms is close to a grand. Plus if I want maximized intake flow, dual carbs would be great. I haven't decided my budget on the build yet. Anything over 3 grand and I should've just bought a better engine. I've seen some Kohler's claiming to push over 100hp and that's on pump fuel
The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

Offline BIG AL 202

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #11 on: March 02, 2017, 08:04:02 am »
All I can say is "GOOD LUCK!"
ALWAYS VOTE FOR ED!   FONGS BROTHER FROM ANOTHER MOTHER!

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #12 on: March 03, 2017, 05:02:58 pm »
mod 28 pistons and pins ordered, should be here in a few days. Port and polish this weekend and bake the pistons when they get here. Rods came in today. I've been thinking on the ignition and I've found some mini pulling tractor coils that might work but I'm not going to over complicate things (more things that could break or fail). So buying a new OEM coil and a tach to see just how many rpms it will push. Got a possible lead on a new used isky cam rooster grind, another on the flywheel for a lot cheaper than new. Miked the valves and they are still tight, so gonna get billet keepers and stronger springs.

Anyone have some info on billet lifters???
The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

Offline PJG56

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #13 on: March 04, 2017, 07:34:58 am »
Stock lifters are fine
Paul Guptill  (oppy) #238modX
2012 slmra mowstock champion(builder/owner)

2013 slmra mowdified champion(builder/owner)
2013 ARMA national champion Mod-X(builder/owner)
2014 ARMA national champion Mod-X(builder/owner)
2014 All American Champion Mod-X/CP(builder/owner)
2014All American Champion FXT (engine builder)
2014 All American 2nd place SP(builder/owner)
2015 All American 2nd place BP (builder/owner)
2016 OutlawTriple Crown FXT Champion (engine builder)

Offline Ace726

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Re: 18hp Oppy running Alky (engine, intake and ignition)
« Reply #14 on: March 08, 2017, 06:19:41 pm »
Pistons just came in today, been looking for a skirt coating but no luck. Probably will do the ceramic for the domes too. Only issue is where can I buy the antifriction compound for the skirts? Molykote, Poly Moly, and Cerakote all make it but only sell to a limited number of distributors. I can get them coated both with skirts and domes for 265. Although I have the 120grit aluminum oxide, blaster, and the oven to do the work myself, just can't find the coating. Has Anyone else looked into this or done this themselves?
The Green Overtaker

Run It Till It Blows Up, Then You Know How Much It Can Handle..... Unless It's a Flywheel.

 

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