Potential 454 Replacement?

[trace elements]

Hey everybody,

I started a thread a little while back discussing 454s in these boats. Let me preface this by saying I would love to put diesels in the boat one day, this discussion should be about gas motors for now. This discussion isn't about saving money by repowering because in reality very few if any of us will ever burn enough fuel through these boats to realize the cost savings of increased efficiency.

I know the feasibility of small blocks in a B31 has been discussed, I think the conclusion is the lack of torque is the small block's biggest drawback. Newer offerings like the 383 stroker motor significantly increase torque, and may even offer more horsepower, although at higher RPM, and isn't a true competitor to the 454.

While browsing Marine Powers Website, I came across their new direct-injected 6.2 LT1 motor. It claims 420 horsepower and 460 ft-lbs of torque. Fuel burn curves show the engine burning ~8GPH at 3000 RPM making 440 ft-lbs of torque. It sounds like this could be a pretty serious contender to the 454. What does the brain trust have to say?

Not to mention, the motor without the catalytic exhaust can be had for under 15k. (I have no idea what a 270 recon Cummins goes for).

https://marineenginedepot.com/62l-di-sportpac

[CamB25]

What would Uncle Vic say about the all aluminum block? No iron!

It seems like a good option. Always nice to talk with someone who did it first, however!

[Bruce]

Use 93 fuel if you want peak performance out of the engine. Not sure how available it is in marinas.
The LT and its more popular brother the LS are everywhere.

The aluminum block won't be an issue with fresh water cooling on the inside, outside will be different story. Not sure if the engine company paints the block but aluminum needs to be etched for the primer and paint to stick good. I use a lot of LS, LSX and LT engines and most come from GM no paint. By the coast down here they discolor quickly with no paint.

[PeterPalmieri]

I have no complaints about my 454s but the 496s are great motor. Higher cruise and better efficiency.

[Carl]

If you are even thinking about putting gas motors into your boat at 15k a pop, look at the package Pete Fallon put in his boat.


Gas power can be a great alternative to diesel performance wise... in my opinion.

i would not go overboard trying to out do great performance with street upgrades.



I went Diesel more for resale value then anything else. Me dumping 20k+ into a boat required the boat value to go up. With gas you may come close or in my case surpass my performance with gas motors. BUT when done your boat will sell as a 50 year old GAS boat compared to my Diesel Powered boat. Or put another way, very little if any return on your investment.

Me, I bought RTO's, did work mostly myself and made most of what I needed...so my cost is quite skewed. If I had to pay for all work done diesel would be less of an advantage.


I was very tossed between high performance small blocks with less weight and cost compared to tried and true big block performance.

[Tony Meola]

Forget the 270 Cummins Recons. They are almost impossible to get now and if you can get them the price is through the roof. It is cheaper to look at one of the more recent Recons.

When I repowered back in 2008/2009 the 270's with Transmissions and guages went for clost=e to $37,000. About 3 or 4 years ago I was told that same package had increased in price to over 60.

[coolair]

I believe a while back there was a thread that talked about the 6.0L and someone that had them in their boat. But not sure the performance comparison of the 6.2 and 6.0.

[Carl]

If you are even thinking about putting gas motors into your boat at 15k a pop, look at the package Pete Fallon put in his boat.


Gas power can be a great alternative to diesel performance wise... in my opinion.

i would not go overboard trying to out do great performance with street upgrades.



I went Diesel more for resale value then anything else. Me dumping 20k+ into a boat required the boat value to go up. With gas you may come close or in my case surpass my performance with gas motors. BUT when done your boat will sell as a 50 year old GAS boat compared to my Diesel Powered boat. Or put another way, very little if any return on your investment.

Me, I bought RTO's, did work mostly myself and made most of what I needed...so my cost is quite skewed. If I had to pay for all work done diesel would be less of an advantage.


I was very tossed between high performance small blocks with less weight and cost compared to tried and true big block performance. Going beyond that depends on what makes you happy, performance wise and wallet wise. How many days will you be able to take advantage of more then a 454 will put out. If it's for the economy aspect...how many hours of running before you see a return. Unless of corse a deal presents itself...

[trace elements]

I have heard references to Pete Fallon's boat, but can't find any information anywhere. Can someone point me towards a link or describe Pete's setup?

[Carl]

http://bertram31.com/newbb/viewtopic.php?f=2&t=11366

[Bruce]

Be careful with the increase in torque and hp that you will be able to turn the props needed.

[Chuckak]

I just purchased a 1970 Bertram 31 Sportfish this spring that had new old stock Mercruiser carbureted 502 Magnum engines (black motors) installed in 2016.
Supposedly rated at 400-420 HP. It is currently over propped as I only get 4250 rpm at WOT at 47 mph. Buying new props this winter to bring the WOT up to 4800 area. Should get well above 50 mph at WOT. Love the sound and the speed. (previous boat was a Fountain 35 with 502s which did over 100 mph) Cruising at 30-35 mph keeps the secondarys closed and I get decent fuel mileage. I troll all day long without issues (other than I cannot go slow enough for walleye). New props and larger rudders should help the trolling issues.
Small blocks will work but they will not last as long pushing a 11-12 thousand pound boat at speed.

[trace elements]

Chuck,

Do you have more information on your setup? trans ratio, prop pitch x diameter, measured fuel burn?

My goal is a reliable, 24-knot cruise, at 1mpg.

My goal this winter is to get the old 454s back into shape with fuel monitors, and see how attainable that may be.

[trace elements]

While I agree the big block torque is unquestionable, look at the power curve for the DI 6.2. This motor is not the 6.0 LS of old, this is a new technology, LS block. The power curve shows it at 450 lb-ft of torque at 3000 RPM. I don't think the old 454s made any more than that.

Crusader 454 = 350 HP at 4400 RPM = 417 lb-ft of torque. ( I know peak torque isn't at WOT and is likely a little higher, but not much)

Marine Power 6.2 DI = 420 HP at 6100 RPM = 460 lb-ft at 4000 RPM. (This is the peak torque number published)

[Stephan]

My goal is a reliable, 24-knot cruise, at 1mpg.

My goal this winter is to get the old 454s back into shape with fuel monitors, and see how attainable that may be.

I have older 454s and get 0.9 mpg. at 24 knots. Keeping the boat light will help I believe skipping the tower/bimini/enclosure may be one of the biggest speed improvements available.

Good luck.
Stephan

[trace elements]

Stephan,

I agree about keeping the boat light, but my boat already has a custom top with an enclosure that undoubtedly hurts speed but makes the fall and spring season much better.

[Stephan]

I agree completely on the enclosure. For a number of years I had nothing but a ball cap over my head. Then a bimini top, and finally this season a full enclosure.
My recollection is that at 20 knots (measuring with the same Garmin GFS-10s) I was getting a solid 1 NM/Gal. Now with the enclosure it is just 0.9 NM/Gal. That is not much of a penalty for the comfort.
I believe the drag gets significantly greater as you go faster and perhaps more so for gassers that get beyond their peak torque.
This season was a nice respite with gas prices.
Regards,
Stephan

[Chuckak]

Chuck,

Do you have more information on your setup? trans ratio, prop pitch x diameter, measured fuel burn?

My goal is a reliable, 24-knot cruise, at 1mpg.

My goal this winter is to get the old 454s back into shape with fuel monitors, and see how attainable that may be.

I miss stated the WOT speed - I am currently getting around 44 mph. The propellers are 18x18 four blade Nibral. I believe the transmissions are 1.5/1 ratio. I will try to verify this
I don't have any fuel data yet - no fuel gauge or fuel flow sensors - on this winter's project list.