Merc 600 faster than a Ilmor 710??
 

THIS IS NOT A POST ABOUT WHICH ENGINE IS BETTER. THIS IS ABOUT THESE ENGINES IN A SPECIFIC APPLICATION.


I know of two west coast MFG that claim the merc 600 is 2mph faster than the ilmor 710.

28ft single engine deckboat. Cat style center pod mod-vp hull (derived from talon).

data:

Both 1.5 ratio bravo xr, stock bravo props, center of propshaft 3" below centerpod

Ilmor 710: 26p 85mph@6300 rpm 16% slip weighs about 4700lbs

merc 600: 30p 87mph@5400 rpm 13% slip weighs about 5000lbs

I can only think of two reasons: weight distribution and prop speed.

What can changed in the setup to get the proper speed from the 710's hp and weight advantage.

Where you using different props for each test?

I dont believe a stock merc 600 can outrun an identically equipped 710 boat.

The merc 600 can be leaned on for ton of power more, but the merc weighs at least 150 pounds more.

I question these data points as being unoptimized from the standpoint that - the numbers on the 710 dont line up from my personal observations (on a different theoretically less efficient hull)

A 26P on a 28ft cat deck seems just a bit off

I run as fast if not faster with a 710 in a 28.6ft stepped V.

I spin a 28 6K just a bit over 6K on a 5300 pound boat.
I can pull a 30 to about 5900 with a light load.


Uncle Dave

I did not do the tests but both props are stock bravo 1. both drives are 1.5 ratio. the ilmor is 700hp at 6300 and is prop'ed with a 26p. the merc is 600hp at 5400 and is prop'ed with a 30p.

400lbs of balast in trunk, and a re-gear to 1.65 on the ilmor boat should make the ilmor boat faster. solves the CG difference, makes the prop size and prop rpm nearly the same.....but that would be silly to add weight and make the drive weaker.

Every boat is different.

It must be the set-up...ilmor should be faster.

Assume this to be true. Other than ballast and gear change what could be done to get the ilmor boat faster?

A guy I know runs the 710 in an Advantantage 27 deck. He says the boat runs right at 85.



Darrell.

Try
1. try a 5 blade prop - It will slip less.
1. a -1 then -2" shorty lower to raise the propshaft a bit
2. swap to an Imco lower unit


Where is the boat located?

Uncle Dave

I have had 3 different engine packages in the same boat with the same drives.

Boat: 2000 38 Fountain Fever running XR's on Imco extension boxes with -2 Imco shorties.

1st set of engines: Merc 525's (a set picked off the production line personally by an accomplished racer and later when I was selling them they were dynoed by Joey Griffen as part of the sale and he said it was one of the best sets of 525's he'd ever seen on his dyno at 570+ hp).

Results: 85MPH is the best I saw running a set of stock 4 bladed Bravos at 5250' ish. on a cool Oct day.

2nd engine package: A set of first Gen Ilmor 625's.

Results: 89 MPH on a moderate July day running a set of labbed 27 P5X's at 5850.

3rd set of Engines. Ilmor Gen 3 710's.

Results have only ran the boat a few times. 94 MPH running stock 27 P5X's around 6200 on a moderate June day. Not sure but I may have been getting in the rev limiter. I have a set of 28 labbed P5X's that should push the boat to around 96 mph.

Merc 525: 85


Ilmor 625: 89


Ilmor 710: 94 (with more in it likely)

I have heard countless people here on OSO recommend the Merc 525's over the 600's because they say the 600's are only a couple to 3-4 MPH faster than the 525's.

I had one of the best sets of 525's that a racer handpicked off the production line and it was at least 9mph slower than the Ilmor 710's that I have only briefly tested with one set of props that are likely too small.

From my experiences Id say the test was flawed.

I have played around with a lot of Nordic Heats...one of them with a 710 Ilmor...and mine with a Merc 600 in various stages of tune. The Heat is a big boat for a single engine.

The 710 Ilmor Heat would run 86-87 mph any day...with a best of 90.6 mph.

My stock 600sci Heat would run a consistent 79 mph any day...with a best of 81 mph.

Having said that...the 600sci boat would simply walk away from the 710 boat in 30-75 mph acceleration tests....and then the Ilmore boat would take the rest of the lake to reel in the 600sci boat....and pass it. the Ilmore motor just doesn't have the torque of the supercharged 600sci.

After putting a Whipple Stage II kit on the 600sci...it would do a consistant 91 mph with a best of 93.8 mph....and destroy the 710 in acceleration.

Just my observations.

Also...my 600sci Heat is an open bow...which tends to be about 2 mph slower than its closed bow bretheren. All my testing was done with the bow cover on.

Chris

The testing has been confirmed by two different mfgs (talon based bottom).

It is true. At least assume it is. a gear change and added weight in the stern would duplicate the 600 in weight and prop speed and prop size.....what else can be changed to make the higher hp lighter ilmor work better?

Take the Whipple upgrade kit off of the 600, and restore it back to Merc factory specs.

The 710 ilmor is faster than the 600 merc. In fact all the testing we did at fountain the ilmor was within a few mph of the 700 merc.

There ya go Ilmor the faster engine!:drink:

it should be. In these boats with the same gear ratio and style of prop ....it is NOT!!!!!!

It is either the lighter engine in the rear causing the heavy deckboat bow to ride wet or it is the increased prop speed causing higher slip % or some combo of both.

Any constructive opinions?

Most who posted stated it is in all boats they tested!

Agreed! All the testing we did at Donzi, the ILMOR was ALWAYS FASTER.

I would say a prop change would make the difference. Maybe a labbed 28 with a little extra cup to get the slip down, or perhaps a completely different prop. Last theoretical possibility would be a slight spacer to get the prop a little deeper and decrease the slip.

First lets talk about prop speed.

the ilmor is turning 6300 rpm with a 1.5 gear ratio.....the prop rpm is 4200. 26 pitch

the merc is turning 5400 rpm with a 1.5 gear ratio....the prop rpm is 3600. 30 pitch

Theoretically these should be the same speed.... http://www.go-fast.com/sterndrive_gear_ratios.htm

is the prop speed a big deal? or is it the 200lbs less weight in the rear of the boat from the lighter engine.

The 700 should smoke the 600 on the top end.....it does not with the same drive height and same style props.

My 600 with whipple kit in a Howard Deck boat hull runs up to 95 mph with a 29 p5x. Don't know if this helps or not because of the whipple kit mod.

Prop speed has to have something to do with it... I know my REV 4 kicks my 3 blade props butt all over the place in performance and slip values except near the top end where the slip on the REV 4 spikes up (don't remember the exact values but if memory serves me correctly the slip number jumped about 10% higher from about 4500 engine RPMs to 5200 engine RPMs and this is through an Alpha SS with a 1.5 ratio). Brett at BBlades said he could fix that for me if I wanted to send the prop back and get it labbed. I am sure the same could be done with whatever prop they used in this test. I did not play with the numbers, but what would the speed be for the Ilmor if you could get that slip down to 13%.

The real question should be what's faster... a 710 Ilmore, or 700 Merc. The comparison to the 600 merc really doesn't make much sense.


Darrell.

The Cigarette on the left has 700 Mercs, the Skater with the in boat camera has 710 Ilmors. Hope this helps!:party-smiley-004:
http://www.youtube.com/watch?v=WgXqGWeboLo

Where did this come from???
 

This test information at this date seems a little pointless. The Merc 600sci's are no longer offered, so it seems less than important to compare it with an offering that Ilmor continues to produce and sell?
Comparing these two engine packages seems a bit of the mark and like comparing a Navel range to a Valencia orange, they are both oranges but still not the same.
The Merc 600 produced about 675HP at the crankshaft and the Ilmor 710 produces about 710HP at the crankshaft so their seems to be a definite horsepower difference. The low end torque of the 600 is definitely greater than the Ilmor at lets say between 3000 rpms and 4000 rpms and they get close to equal somewhere around 5000 rpms , where the 600 peaks HP at about 5300 rpms and the Ilmor peaks at about 6000 rpms. There is really no way these two engines will be propped the same with the same final drive ratio the same so they cannot be compared with same drive ratio and same prop spec.
Merc obviously knew that the 600 sci was underpowered for its cost and configuration and elected to remake the 600 as the newer 700sci and there is a current engine that can be compared to the Ilmor 710's. Still a great bit of difference there too as one is supercharged and one is naturally aspirated, so differences still exist. Comparing a Skater w/Ilmor 710 to a Cigarette with a 700sci is also not a good equal playing field comparison.
Conclusion:
Both Merc Racing and Ilmor make great marine performance engines and each has good choices for owners and boat builders to draw from and fill the "NEED for SPEED"!
This post is starting to sound like a winter time "Cabin Fever" banter post, with that I am back to "Summer"!

Best Regards,
Ray @ Raylar

"Comparing a Skater w/Ilmor 710 to a Cigarette with a 700sci is also not a good equal playing field comparison."
Hence, the party smiley! :evilb:
I was actually impressed with how well the cigarette ran!

Ray,
Don't know where you heard that the 600 Sci is being dropped by merc..... Here it is listed on their website,

http://www.mercuryracing.com/sterndrives/hp600sci.php



and in fact AT just debuted 37' w/ 600Sci's


http://www.offshoreonly.com/forums/g...poker-run.html.

And I agree comparing 600 Sci's and Ilmore 7-10s are apples to oranges....
Dean

Ray,

Respectfully, you missed the point.

How does one get a 710 to outperform the merc 600 in a 28ft, talon based, single engine, 5000lb deckboat?

I just thought that a comparison to the 600 would give a clue as to what should be changed to run the ilmor.

Obvious answer: 1) slow the prop to 3800 rpm with a 1.65 gear change (this would be similar to the 600) 2) move or add 250lbs to the engine compartment.

I think that weakens the drive and who wants extra weight. Is there something else that should be done such as a standoff, x-dimension, and or prop

Do you own this boat?

You've gotten a few tips already.

It can take a dozen or more trial runs just to get the ideal prop for a given rig.



Uncle Dave

Me make a mistake-yep
 

Dean and others
I stand corrected again. I had heard the 600sci was only being made as the 662sci for use in Europe and the 700sci was replacing the 600sci. This was conversation back in 07'-08' and I just never kept up on their continued offering. My mistake, I guess to busy with other things to stay up on all Merc's offerings.
In any event properly comparing these two engine packages in any boat would require the builder to dial in the setups to hopefully achieve best performance with both engine, drive and prop setups.

Best Regards,
Ray @ Raylar

I would think that the 710 would be faster than the 600 if they both were stock. If the Merc has been reflashed with a different pulley then it should run away from the Ilmor. In stock configuration are you saying the 710 is slower than the 600? I thought the 600 in stock form was unresponsive and unimpressive. After it was reset...Wow! big difference

When did you do the test at Donzi with the Ilmor?

What boat or boats were used in the test?

What drives were used in the test?

Thanks.

+1. Gets my vote here.

yes the problem seems to be the setup.

I think the problem is bow lift with these deck boats. relaxalot and others say that the P5X is the best running prop. From what I understand P5X is a bow lifting prop with a little extra transom lift due to the 5 blade.

The ilmor boats don't respond the same to the p5x.

Would higher prop rpm and lighter engine cause the transom to lift more making an even bigger problem with bow lift?

What can be changed with the bravo prop to decrease transom lift?

In 2006 and 2007
The 38 ZR and 43 ZR
Bravo XR's, Imco's and no.6's
I bet you allready knew that Dolph :)

I think one problem with the setup is the difference in the engine weight in the back of the boat. It should slip more with an Ilmor. When big blocks were removed from my velocity and Ilmors installed the boat was sitting about
2" higher out of the water. The major difference between the
merc's 600's or the 700's is the Ilmor has an advantage of about 30 to 35% better fuel economy.