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Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

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Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Sat Aug 01, 2020 9:02 am

2 part topic feel free to comment either/or:

1. My Dad’s 2003 22’ Tjet had several cracked spark plugs one of which had the electrode break off inside the cylinder and grenade it. Any theories why this would happen? We are thinking that when he winterized it last fall and took out the spark plugs to smog the engine the temp change that time of year may hav had something to do with it. He cranks them down about a half turn from hand tight. Interesting multiple were cracked.
2. Much more exciting is it is repower time! We have done a fair amount of research and landing in the newer L87 6.2 DI from Kodiak. Mechanic likes this combo with the 212 and his boat has been ok with the 5.7 MP but a little piggish when loaded up so hoping for a decent upgrade between the more power and less weight. He has the work done in Lewiston so with KEM right there it’s another plus. Appreciate any feedback on the engine choice and see you out on the skinny water!
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Eagle1 » Sat Aug 01, 2020 10:07 pm

1. Close couple?
2. Sand Trap ?
3. One fuel tank or two ?
4. Don't run boat on trailer out of water.
5. Who is doing the work ?
6. The Kodiak 6.2 is a good engine.
7. Put a low drain ball valve between sand trap and feed water to engine.
Good Luck.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Sat Aug 01, 2020 10:29 pm

Thanks ! Not sure in close couple. Had a sand trap on will not be run out of the water. Guys Marine doing the work.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Sat Aug 01, 2020 10:30 pm

1 fuel tank.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Sat Nov 21, 2020 8:20 pm

Update: got the boat back and took her out for the maiden voyage on Roosevelt. What a difference! Hole shot much improved and felt like two boat lengths to get on step. Cruise at 3000 rpms, 30 MPH. Estimating top end at 55. Oh boy! Ended up with its the 3.4 impeller. It feels like an afterburner when you get on it compared to the 5,7.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Ak_Riverrat » Tue Nov 24, 2020 2:07 pm

What is your rpm at WOT?
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Riverjohn » Tue Nov 24, 2020 4:03 pm

6.2 DI?? Or 6.2 ??
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Tfbruin » Wed Nov 25, 2020 7:48 am

Very interested in this info, following. I have been thinking about doing the same thing with my 5.7 and have been looking at a 6.2 DI. That way if the boat is really loaded up the weight would not make it feel so sluggish. I’m at a higher altitude so it makes a difference, 4000’. Also want to put in a gull wing door at the same time.
2011 21’ Custom Weld Storm 350 212
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Thu Nov 26, 2020 11:56 pm

It is the 6.2 DI. Still too new to do extended WOT but estimating 4250 rpm or higher. We’re at 2 hours on the engine so once we have the first 10 I’ll post back with more definitive info. Estimating about 200lbs lighter at the back end and it’s noticeable.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Riverjohn » Fri Nov 27, 2020 10:55 am

Chad74 wrote:It is the 6.2 DI. Still too new to do extended WOT but estimating 4250 rpm or higher. We’re at 2 hours on the engine so once we have the first 10 I’ll post back with more definitive info. Estimating about 200lbs lighter at the back end and it’s noticeable.


Probably closer to 90 lbs.

From Kem:
Vortec 5.7L V8
Engine Mass: 807 lbs. (366 kg)

6.2L V8 VVT DI (L87)
Engine Mass: 717 lbs. (325 kg)
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Chad74 » Fri Nov 27, 2020 7:53 pm

Thanks I’ll double check with my dad on where he got the 200lbs figure. It was a Marinepower unit vs KEM but not sure that would explain an extra 100lbs.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby truckiedh » Fri Nov 27, 2020 8:19 pm

I just scaled a 98 Marine Power SBC that i bought. Complete engine in running trim, aluminium intake and exhaust, dry no fluids. 672 lbs.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Riverjohn » Fri Nov 27, 2020 8:33 pm

truckiedh wrote:I just scaled a 98 Marine Power SBC that i bought. Complete engine in running trim, aluminium intake and exhaust, dry no fluids. 672 lbs.

Pics? :Drink: :Drink:
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Riverjohn » Fri Nov 27, 2020 11:19 pm

truckiedh wrote:I just scaled a 98 Marine Power SBC that i bought. Complete engine in running trim, aluminium intake and exhaust, dry no fluids. 672 lbs.

Interesting Marine Power shows it at 750 lbs. It looks like this is without the Freshwater Cooling system too. So with the Heat Exchanger included with that the weight would be more.
This is Cast Iron block and heads with Aluminum intake. So at 672 lbs. I wonder what you are missing? :Drink: :Drink:

http://marinepowerusa.com/wp-content/up ... 7-VR-B.pdf
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby truckiedh » Sat Nov 28, 2020 1:27 am

Riverjohn wrote:
truckiedh wrote:I just scaled a 98 Marine Power SBC that i bought. Complete engine in running trim, aluminium intake and exhaust, dry no fluids. 672 lbs.

Interesting Marine Power shows it at 750 lbs. It looks like this is without the Freshwater Cooling system too. So with the Heat Exchanger included with that the weight would be more.
This is Cast Iron block and heads with Aluminum intake. So at 672 lbs. I wonder what you are missing? :Drink: :Drink:

http://marinepowerusa.com/wp-content/up ... 7-VR-B.pdf


There are a couple of pictures in the market place under "383 For Sale" . That is exactly how it was weighed. Yes, cast iron block and heads. It is all there including the flywheel, the rest of it you can see. That is unless I open it up and find someone forgot to put the guts in it.
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Re: Re-power feedback 22 Thunderjet 6.2 L87 212 Hamilton

Postby Riverjohn » Sat Nov 28, 2020 11:26 am

truckiedh wrote:
Riverjohn wrote:
truckiedh wrote:I just scaled a 98 Marine Power SBC that i bought. Complete engine in running trim, aluminium intake and exhaust, dry no fluids. 672 lbs.

Interesting Marine Power shows it at 750 lbs. It looks like this is without the Freshwater Cooling system too. So with the Heat Exchanger included with that the weight would be more.
This is Cast Iron block and heads with Aluminum intake. So at 672 lbs. I wonder what you are missing? :Drink: :Drink:

http://marinepowerusa.com/wp-content/up ... 7-VR-B.pdf


There are a couple of pictures in the market place under "383 For Sale" . That is exactly how it was weighed. Yes, cast iron block and heads. It is all there including the flywheel, the rest of it you can see. That is unless I open it up and find someone forgot to put the guts in it.

That picture shows a lot of Heavy things on it. I am going to weigh the 383 I have in my little boat the next time i have it out of the boat. Mine is Iron block, Aluminum heads and intake. Also has Kem Heat Exchanger and Aluminum Exhaust Manifolds. :Drink: :Drink:
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