Mercury and OMC Race Engines - Max HP @ RPM ratings - Late 60's through md 80's

[194268]

Welcome to Scream & Fly 194268. What year were you in Mercury advanced research & what were you working on at the time?

I use to be 194264 or was it 194265, can't remember, it's a B----- growing old. Anyway I left OMC Snowmobile Engineering the end of August 1973 and started in Advance Research the next Monday in Sept '73. Like I said worked with Les Cahoun, Lyle Forsgrin (sp) another Tech named Bob Menlesskie (sp),
Most of the time was spent on Snow Twisters, some time on the inline sixes and a pet project for Dr. Morgan. He was working on flaps mounted on the rear of racing hulls that could be move like an airplane wing flap to reduce boats blowing over. Would like to add that Les also has a PHD Degree in sound engineering, and he developed the expansion chambers for the Snow Twisters. I left Mercury in June of '74 due to Marital problems, mine.

[Raceman]

I've posted this before, but some of you guys may've missed it:

Sometime in the last 15 to 18 years I ran across a Switzer Shooting Star with a Twister in Hemmings Motor News. The guy lived in Idaho, but I called anyway. He ALSO had a Twister1 upgrade kit with it, new in the box and never opened. We couldn't work out the lagistics of getting the boat and motor all the way 'cross country, so I bought the upgrade kit. I called the guy periodically over the next several years, and he finally told me one day that if I'd buy the boat and motor for what he originally advertised it for that he'd bring it to me in Georgia.

I believe it was/is the most original and unmolested Twister on the planet, UNLESS Merc or somebody else has one new in the box. The guy said the boat/motor had less than 10 hours on it............ his daughter (now adult and accompanying her Dad on cross country trip) argued less than 5 and said more realistically 1 or 2. She said her family bought it as a pleasure boat, her mother hated it because of the noise, and basically they took it to the lake and ran it a time or 3 and then put it in the garage where it stayed covered up for something like 20 yrs or more. The stickers look new as does the paint, and there aren't even any stains on the powerhead.

Anyway, back to the kit, and what it contained, since MAYBE it would shed some light on the differences between the Twister and Twister1. There was a new block, new transfer port covers, new pistons, switchbox, rings, exhaust log, and top and bottom cowls. (no carbs and no connecting rods) Also a different throttle cable mount and tons of small parts........... nuts, bolts, gasket set, blue stickers, etc, AND a T2 crankshaft, new in the box also and still sealed with factory staples INSIDE the T1 upgrade kit. The crank has always been a mystery. Obviously it couldn't have been run in the Twister/Twister1 style block without machining 3 of the ridges for the main bearings that the T2 used on every main journal. I've always wondered if this was an intentional way for them to change the firing order on the T1 upgrade kit from the standard one to the T2 (although it would seem that Merc would have machined the ridges before they shipped it) OR was it a simple boxing/shipping error in the kit. I don't have a disassembled Twister block for comparison, but it would be interesting to have one to compare to.

[velox]

It's on my calendar and some of the OFF guys are making noises about flying in..... if we're still alive by then.....

I'am still alive and still making noises!
For once, I am sitting on the sidelines absorbing all of the information you guys are coming up with.

[seeroy]

I'am still alive and still making noises!
For once, I am sitting on the sidelines absorbing all of the information you guys are coming up with.

It's about time you showed up!

[Riverratt]

Not all the racing V-8's were 3.5's. They were different sizes different years. I can quote the sizes and years later.

How are you making out with the V8 info?

[Mark75H]

From 80 to 85 they were 3.5 (3503.36cc's)

I think it was 86 when they were punched out to 3.6 liter/220ci (3.5" bore)

and 87 when they went to 4.0 liter/244ci (3.685" bore)

In 88 & 89 they were 3.0 liter/183ci to meet the F-1 rules (3.3" bore)

[racer]

V8 race engines were as Mark75 mentioned 3.5 stock bore at that time was 3.600 with a stroke of 2.588. I am sure that was the bore and 90 percent on the stroke. I have some pistons that I double checked for the bore. Correction 2.625 stroke on race version 8 I mistakenly put crossflow stroke.

[Mark75H]

Ooops ... I should have turned another page in my notebook.

Racer is right on the 3.5 liter bore size of 3.6"

My notes say the stroke of the 3.5 is 2.625" and the 3.0 used the same stroke,

but the 3.6 and 4.0 used 2.858" stroke

I don't have the ambition to do all the math and confirm all these numbers right now.

[Instigator]

flyer from S.E. for their 3.5 Offshore lists stroke at 2.625"

390 HPs, w/a operating range of 7K to 8250 on regular, leaded pump andddd, a 60 day warranty

[dale robertson]

Would like to add that Les also has a PHD Degree in sound engineering, and he developed the expansion chambers for the Snow Twisters. I left Mercury in June of '74 due to Marital problems, mine.

I worked with Les untill he retired last year and moved back to Florida. He is also did most of the OMC V-8 development work and engineering at Second Effort. He told me the smaller displacement V-8's made as much peak power as the 4 liter's they just didn't have the midrange torque.

[Mark Poole ModVP]

Hey T2X...what made a 2.4 Champ motor a piece of crap?...Lol

[90 5.0]

Anyway, the best comparison was two guys here that had Venture bassboats and changed engines like I change shirts..

I haven't seen a Venture bass boat in probly 20 years or more. Memories, wow.

We had a ??xp-18?? I don't really remember the boat model that well with a 200 blk max. I think from 1980?? to 84?? We went from a skeeter wrangler with a 225(death trap) to the venture with the 200 and then to a starfire with a 150(damn tournaments started making you have a legal boat/motor combo). That's ok, we hopped it up later on in life

The venture from what I remember was a really good /stable running boat even as over rated as we were, I was pretty young still when we had the venture. I need to scan some pics, my dad had Snoopy and woodstock painted on the side of it for me(oh the 80's lol).

[FMP]

I was searching for this thread because it has the L6 hp numbers. I knew it was said 210+, 220. I had a conversation with someone who recalled a dinner conversation with R Molinari about his T2X which he ran in the 1972 European Championship. He , Molinari conceded that his T2X was putting out well over 220hp. A video still exists of the first heat of that race and the acceleration from the start and out of the turns was said to make the 220+ statement believable.

[FMP]

I use to be 194264 or was it 194265, can't remember, it's a B----- growing old. Anyway I left OMC Snowmobile Engineering the end of August 1973 and started in Advance Research the next Monday in Sept '73. Like I said worked with Les Cahoun, Lyle Forsgrin (sp) another Tech named Bob Menlesskie (sp),
Most of the time was spent on Snow Twisters, some time on the inline sixes and a pet project for Dr. Morgan. He was working on flaps mounted on the rear of racing hulls that could be move like an airplane wing flap to reduce boats blowing over. Would like to add that Les also has a PHD Degree in sound engineering, and he developed the expansion chambers for the Snow Twisters. I left Mercury in June of '74 due to Marital problems, mine.

Advanced research, can you talk about it?

[Capt.Insane-o]

Hey T2X...what made a 2.4 Champ motor a piece of crap?...Lol

The cylinders turned into octogonolinders