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07-28-2001, 11:30 AM #1Guest
We recently recommended to a customer of ours that he not spend the money at the present time on having a flywheel lightened. We then received an E-mail from another vendor in the business challenging our opinion to this particular customer and the advantages of a lightened flywheel. We decided to run some real factual investigation into the pros and cons of such a flywheel by testing several and here are the hard facts from those test. Test engine: modified Mercury 300 drag. Heads 26cc. Compression as shown on snap on gauge with 24 volt starting system:168psi on all 6 cylinders Fuel: 100 LL av gas with additive. Oil: Klotz Super Techniplate at 32/1. Spark Plugs: NGK BR 9 HS10 Timing: 25 degrees max ECU: Merc A-63 w/56 lb regulator. ECU setting: 102.6 Fuel pump: weldon 90-120 psi aircraft grade fuel injection pump. Operating temperature: 155 degrees farenheit. All test were conducted in controlled enviroment at 80 degrees and 70% humidity on a Stuska A-600 turbine waterbrake powerhead dynomometer.
Test 1: stock Mercury aluminum flywheel as shipped with the engine. Peak horsepower at 8300 RPM 328.306 torque 204.829 ft lbs. Test 2: Factory Mercury flywheel lightened by Diamond Marine. Peak horsepower at 8300 RPM 328.303 torque 204.828 ft lbs Test 3: Factory Mercury flywheel lightened by unknown. Peak horsepower at 8300 rpm 328.283 torque 204.808 ft. lbs. Test 4:stock 16 amp steel flywheel, horsepower at 8300 rpm (we don't recommend this as there is a danger of disentegrating the flywheel) 329.121 torque 205.454 ft. lbs.
Test 5: stock factory left hand aluminum champ or S-3000 flywheel, horsepower at 8300 rpm, 328.313 torque 204.848 ft lbs. Test 6: Jay Smith lightened left hand aluminum flywheel, Horsepower at 8300 rpm 328.307 torque 204.839 ft lbs. We found that the stock aluminum flywheel made in reality as much or more actual usable horsepower as any flywheel tested except the slight increase that was noted in the stock steel unit which could be attributed to inertia from the added weight.Is the lightened unit worth the cost?? We believe it is an aid to engine longivity, especially in the upper 8000 rpm range and above, but as for a horsepower gain, there is absolutly no noticable gain at all according to our test. The Jay Smith and Diamond Marine units were both first rate and while the finish work on the unknown unit was not quite as neat they all performed well. There was a slight difference in the weight of the three with the Jay smith unit being slightly lighter than the Diamond Marine unit and the unknown unit slightly heavier than the other two. All three were considerably lighter than the stock aluminum units. This test in no way shows what increase or decrease in what the performance on an actual boat might be and was done solely for the purpose of an overall look at actual horsepower and torque readings. These test were done independently by Eagle One Performance Products and are neither intended to recommend or not to recommend the use or quality of any product by any of the vendors products that were used.
Eagle One Performance Products
[Edited by EagleOne on 07-28-2001 at 03:17 PM]
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Glasstream15 liked this post
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07-28-2001, 11:45 AM #2
We have never expected a lightened flywheel to make more top end horse power in fact it should make less. The #1 point in a lightened flywheel is to stop the top of the crank from coming off at 10,000 RPM. or for that matter at 8000 RPM. But what your test really doesn’t show is the torque gain on acceleration dew to spinning up a lighter mass. In an F1 boat a lightened flywheel is a noticeable gain in acceleration off the turn. On my dyno, as long as the motor is accelerating, the lightened flywheel will make 10 more HP over the stock S3000 type.
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Corona Mike thanked for this post
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07-28-2001, 11:57 AM #3Guest
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Noah, just out of curiosity
4 of the 5 test showed very similar numbers, the test #4 with the 16 amp steel flywheel was signifcantly higher, what's the reason for that?
I understand the NON recommendation for the possibility it may disentigrate, where would we find those 16 amp flywheels in use, so we know what to "watch out for"?
Are there applications you DO recommend a lighten flywheel such as spinning higher rpms?
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Glasstream15 liked this post
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07-28-2001, 01:11 PM #4
Great test.....thanks, and.....
where can I find out more about the Stuska A-600 turbine waterbrake powerhead dynomometer? Does it hook to the propshaft, or do you install the powerhead "on it" so to speak? I use both a K & O and a Land and Sea (never been very happy with the Land and Sea...terrible electronics, the water brake loading part of it is ok).
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Glasstream15 liked this post
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07-28-2001, 03:35 PM #5Guest
Edited earlier post and Stuska Dyno info
The earlier post had a misprint on the information regarding the steel flywheel as there was only about a 1 hp gain, we have edited that post. The 16 amp steel unit is from a 1983-85 200 2.4 merc. As for the questions about Stuska dyno's they are true powerhead dynomometers and are driven off the crankshaft on test stand housing which allows us to test things such as tuners, exhaust temperatures, water temps at several points on the block and much more without going through the lower unit or driving a water pump. Photos of our unit in use are shown in our shop tour on our web site at http://www.eagleoneperformance.com . For more information you can contact Stuska Engineering Company, the last address we show was 2930 s. Fox St. ,Englewood Colorado 80110 303-762-0553. Please excuse my errors in typing ,I smashed my thumb, it hurts like hell and the bandage gets in the way.
Noah Legear/ Eagle One Performance Products
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07-28-2001, 08:36 PM #6
Thanks for all the info and....
keep your thumb away from the flywheel!!
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07-28-2001, 09:14 PM #7
I DONT THINK ANYONE INTENDS FOR A LIGHTER FLYWHEEL TO INCREASE HORSPOWER. A LIGHTER FLYWHEEL HELPS THE STRAIN ON THE DRIVETRAIN AS WELL AS ALLOWING THE MOTOR TO TURN UP QUICKER. THIS ADVANTAGE MEANS ALOT TO ANY RACER WHO WANTS TO HIT THE FINISH LINE FIRST. EVERY LITTLE THING YOU CAN DO WILL ALWAYS HELP YOUR CHANCES OF WINNING. ANYONE WITH A LIGHT WEIGHT BOAT WOULD BENEFIT FROM A LIGHTER FLYWHEEL WHETHER THEY DRAG RACE OR NOT. ONLY HEAVIER BOATS WOULD NOT BENEFIT FROM IT. OBVIOUSLY THERE ARE VARYING OPINIONS ON THIS BUT I WILL STICK WITH THE MAJORITY ON THIS ONE.
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07-28-2001, 09:21 PM #8
Hey Mercman, Your right, I was going to add that earlier but didn’t. A heavy boat will only benefit by diminishing crank strain, increased acceleration will be so slight, it will go unnoticed.
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Glasstream15, Superbender liked this post
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07-28-2001, 09:39 PM #9
JOHN , YOU DA MAN! I THINK WHERE GOING TO START THE "REAL HARD FACTS FAN CLUB" I DONT LIKE STEPPING ON TOES BY ANY MEANS BUT I FEEL THE GENERAL PUBLIC BENEFITS FROM THE WHOLE STORY INSTEAD OF JUST ONE SIDE. WHEN BOTH SIDES OF ANY OPINION ARE JUSTIFIED BY EACH PERSON (PROS AND CONS) IT REALLY HELPS OUT. IM NOT HERE TO SELL ANYONE ON ANYTHING.
"JUST THE FACTS MAM"
P.S. DO I MISS MY STV? MY ALLISON ? YES I DO BUT THIS (SKATER) RIG IS BAD TO THE BONE IN THE RUFF STUFF. IM GONNA GET ANOTHER BOAT THIS WINTER TO TOOL AROUND IN BUT I DONT THINK I WILL EVER GET RID OF THIS SKATER! I HOPE WHEN THE TIME COMES TO PUT TWINS ON THE 21 SKATER I WLL BE ABLE TO MAKE IT A FULL PROJECT TO SEND TO VIRUS FOR THE MAGAZINE! THIS WINTER WILL BE QUITE THE BUSY ONE FOR ME!
MERCMAN OUT: TALK TO YOU GUYS AFTER MY AWESOME DAY ON THE ISLANDS TOMMORROW IN THE SKATER!
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07-28-2001, 09:49 PM #10
You’re so right, that’s the way to learn, listen to all the opinions and then form one of your own, or at least go with the majority. Have fun!
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07-29-2001, 04:26 PM #11Scream And Fly VIP
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I will have to agree a light flywheel was never meant to increase power, its for longevity and acceleration only.
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Glasstream15 liked this post
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07-29-2001, 06:34 PM #12
As a baseline how fast can you spin on a stock flywheel and when should you switch to a lightweight?
'90 STV
'96 260
under construction
for far too long
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07-29-2001, 07:25 PM #13
Mercury switches to the lightened flywheel at around 6000 RPM. Maybe you can push this higher but every few 100 RPM you increase putts 100s of LBS of twisting torque on the end of the flywheel as you accelerate and decelerate.
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02-16-2017, 07:48 AM #145000 RPM
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Great thread(s)....I have one posted on this topic, but found this later. I'm building a SBC and want very good acceleration response. The current Mercruiser flywheel is very heavy and won't help my cause! I am interested in an aluminum/light weight flywheel just for the transient response from a stepped input.
Can anyone point me to a cost-effective low-mass flywheel (and coupler) that will bolt into a SBC/Bravo One powertrain? Thank you!
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02-16-2017, 11:08 AM #15
I know nothing about Mercruiser flywheels. It's all about outboards baby. I'm sure the same principles apply. A lower revving motor and a heavier boat are not going to benefit much.
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