"Name That Outboard"

[Tim Kurcz]

To Bill, Thank you for such a thoughtful post. I'm honored and humbled to be compared to Smokey - I've read his book - and like you pointed out, develop what the rules don't restrict. The 45SS twin "Piranha" is one of my finest examples.

It will be developed in the tank this winter, ready for the lake next spring. The goal is 2hp/cubic inch which will put it in league with most triples. At 40# lighter and shorter, this engine on a D-mod hydro with a light driver will be quite competitive in FE/850, especially on tight courses.

Though I've never modified a late model alky, I've had the Quincy's and Parker loopers apart. As Al Lang pointed out - it doesn't matter what engine make or displacement, there is almost always room for improvement - depending on the rules. If you've got a PRO that needs help I'll be glad to look at it.

Thanks again, you made my day! Tim

PS: If you look closely at Tom's photo's you'll see the progressive carb linkage neatly in place. Also you're right - I always build a little edge into my own equipment.

[Tim Kurcz]

For Powerabout, Good try - Emissions control is not a goal, and mods run on gas & oil. Hint: 4-plugs will deliver a faster burn. Otherwise you're right, the spark is split between two fully independent ignition systems, actually cross firing two plugs in opposite cylinders to accomplish the light-off. The question stands: What is the theory behind the multiple plugs?

Tim

[Powerabout]

Tim
The burn will be faster as you say plus the flame front travel will be shorter as the plugs are closer to the cylinder wall.
More complete burning to help prevent a lean detonate?
Small plug gap so shorter rise time before firing so less chance of missfire?

I dont really know the multiple plug story in a 2 stroke never read the SAE paper on that.
I see 2nd Effort did them for their V8's but I dont know why,
along with Land & Sea.
Cheers

[Tim Kurcz]

Burn rate is faster indeed. Though it may have some effect on resistance to detonation, that is not the intent. Hint: Faster burn allows a shorter spark lead (advance). Why bother?

[Powerabout]

then you wont need a spark retard device at high rpm but gain the low end with the correct tiiming at that rpm and therefore less sensitive to exhaust tuning as well?

Easier to pull start when using fixed advance?

[Tim Kurcz]

If we could light off the mixture later because of multi-point ignition, say at 10 degrees BTDC instead of 20, it makes sense there will be less energy lost overcoming rising cylinder pressures BTDC.

[Mark75H]

Isn't the same thing often achieved with turbulence?

[Bill Van Steenwyk]

Tim:

The reason I mentioned the PRO category as one you might look toward to further showcase your talents, is there is no rule book (per se) to get in the way of creative, original thinking, other than the CC displacement limits of the individual class you want to work with, insofar as engine/motor mods. Even though it is always fun and I am sure you get a great kick out of "working" the rule book in the MOD category, you can still have the "in the spirit of the rule" thing bite you if the Technical Committee you have to deal with decides you went too far and makes your modifications illegal, even though they meet the "letter of the rule", just because they don't want someone running away from the competition for whatever reason, ala NASCAR these days.

I appreciate your kind offer of engine help, but my racing days are over. I did manage some accomplishments, met a lot of good folks (some of whom even still talk to me, no matter the "radio rule" controversy several years back) and all in all had a great time being involved in boat racing from the mid 50's until 2004.

Good Luck in your future engine building and racing endeavours. With the type workmanship and thought process that goes into your engines, you can't help but be successful. I will look forward to seeing more of what you come up with in the future.

[Tim Kurcz]

Here's my best to catch up on all.

For Al and Jeff, I'm driving this one with assistance from Jim Robb, Jason Hay, and Rich Welch. This will follow careful indoor tank testing this winter to sort out the bugs.

For Sam, I have no knowledge of combustion turbulence theory, but know spark timing and flame front are controllable; something I can develop with less than factory tools and funding.

For Bill; Again, I'm humbled by your thoughtful and eloquent post. Engine design and development developed into a passion in the mod division primarily because alkys were way beyond my reach. Mentors were Bud Parker, Harry Brinkman, Harry O'Brien, and Mercury master mechanic John Carlsen - mostly stock/mod guys. My goal is to build on their teachings and support the sport with ever improved engine technology. Gotta tell you, in the few races where I raced the Mod with alkys, I found the sweet smell of castor and alcohol, well intoxicating! That said, shoud the opportunity ever arise, I'll most certainly take a shot at alky building.

In case any answers were missed, I'll take a shot at it later. Thanks to all for your interest and comments. I'll post performance detail as it develops.

[Tomtall]

Tim - Thanks for allowing me to share your project on the net. It's always fun to post your exotic mods here on BRF.

Here is the spec. sheet Tim had posted with his new build at the fall meet.