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Thread: Got my 18:1's

  1. #1
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    Default Got my 18:1's

    Ceramic tops. Microslick on the skirts. Finally can get the block work going!

    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  2. #2
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    Looking very very nice..

    Gonna boost it good and aftercooler it ???
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
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    Quote Originally Posted by JeepSJ View Post
    Ceramic tops. Microslick on the skirts. Finally can get the block work going!

    What other parts are you going to use in the build?

  4. #4
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    Quote Originally Posted by Robyn View Post
    Looking very very nice..

    Gonna boost it good and aftercooler it ???
    Not too crazy...probably limit to 15psi. Yes with the cooler.

    Quote Originally Posted by Aftermath View Post
    What other parts are you going to use in the build?
    Navistar block, mostly stock other stuff. I'll do some match porting on the intake and exhaust, ARP head and main studs, air/water intercooler setup, etc... Not going for ultimate max power...want good power with reliability.
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  5. #5
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    15 psi max with a good aftercooling will be sweet.

    Big issue with the 6.5 is that it does not have enough head bolts for more boost.

    These engine can do real nice in a truck if you don't try to go beyond 350 HP

    300 is a lovely sweet spot as well.

    Getting rid of the heat is the tough order on these.

    Nearly all the combustion heat is up in the heads and its hard to get it to the coolant fast enough.

    Have fun on the build.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  6. #6
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    Quote Originally Posted by JeepSJ View Post
    Not too crazy...probably limit to 15psi. Yes with the cooler.



    Navistar block, mostly stock other stuff. I'll do some match porting on the intake and exhaust, ARP head and main studs, air/water intercooler setup, etc... Not going for ultimate max power...want good power with reliability.
    So what type intercooler and where are you going to mount it?

  7. #7
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    Are these the latest Kennedy Pistons?
    1982 C10 SCSWB 6.5TD, mods too extensive to list. (13.69 1/4 mile @94.6 MPH) RACE TRUCK
    1982 C10 SCSWB 6.2NA, 2.73 700
    1986 C10 SCLWB 6.2TD 3.73 700
    1989 V20 SUB 6.2NA, 3.73 400
    1994 G20 VAN 6.5NA, 3.42 60E
    1994 K20LD ECSWB 6.5TD, 3.42 80E
    1995 K20 SUB 6.5TD, Wrecked, ran into by stupid teen.
    1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
    1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
    1994 C20HD ECLWB 6.5TD 3.73 80E Wifes Truck.
    1995 C20LD ECSWB 6.5TD 3.73 80E
    1995 K20LD SCLWB 6.5TD 3.73 80E
    1996 K30 DRW 6.5TD 4.10 80E
    1997 C10 Tahoe 2Door 2WD 5.7L to 6.5 Conversion Underway

  8. #8
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    Quote Originally Posted by Aftermath View Post
    So what type intercooler and where are you going to mount it?
    Using a water/air setup. Space is very limited under the hood of my Jeep, as is the area for the cooling stack.

    Quote Originally Posted by john8662 View Post
    Are these the latest Kennedy Pistons?
    I worked with RJ from Schoolcraft on these. Well, he did all the design and production, I just funded it. Kennedy wasn't interested in making any more when I talked to him so I went a different route.
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  9. #9
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    Quote Originally Posted by Robyn View Post
    15 psi max with a good aftercooling will be sweet.

    Big issue with the 6.5 is that it does not have enough head bolts for more boost.

    These engine can do real nice in a truck if you don't try to go beyond 350 HP

    300 is a lovely sweet spot as well.

    Getting rid of the heat is the tough order on these.

    Nearly all the combustion heat is up in the heads and its hard to get it to the coolant fast enough.

    Have fun on the build.
    Toying with the idea of ceramic coating the chambers, valve faces, and exhaust ports to try to keep heat out of the heads. We'll see where I go.

    I'm not so much concerned with 300hp as I am with getting 500ft/lbs of torque.
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  10. #10
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    Feb 2000
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    Montana
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    Arrow

    It's not boost pressure that can weaken head gaskets... It's combustion pressure.

    15 or 20 psi boost pressure is small change compared to up to 3000 psi combustion pressures possible. So, it's really the amount of fuel that has more to do with peak combustion pressure. Since the fuel injection pumps were designed around the fueling specs for these engines, it would be hard to deliver enough fuel along with whatever amount of boost to exceed the design limits of the head gaskets/bolts.

    Also, I believe injection timing is more important than boost pressure where head gasket longevity is being considered. Next, order of importance could be average power output (i.e. a long distance hauler might have different head gasket longevity than a weekend warrior).

    Now we come down to it..... Peninsular told me way back when that they had never seen an 18:1 CR 6.5 with failed head gaskets (w/big marine turbochargers). Further, I was told they went to 18:1 pistons in the first place for the durability improvement over the 21.3:1 CR on-road engines they tested. A marine 6.5 runs at far more power for far longer duration than a pickup truck engine. Jim

  11. #11
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    Default

    Pistons look very good. I had heard RJ was going to work on taking over these, good to see that he has and the product looks great.

    Thanks.

  12. #12
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    For what it's worth...

    My Suburban was totaled two and a half years ago along with my travel trailer in a wreck on I-70 in western Illinois. I am finally back up and running with that engine in a 2000 Chevy K3500 Crew Cab DRW Long Bed truck.

    I have had two head gasket failures with Fel-Pro gaskets since building my engine the first time in 2005. I have started using Cometic MLS head gaskets to solve the problem.

    The Fel-Pro gaskets cannot hold the cylinder pressure that my engine creates with 25+ psi boost and all the fuel the DS4 can deliver.

    After freshening the engine with new rings and installing a new forged steel crankshaft from GEP purchased through Kennedy Diesel (picked up at the plant) and a new set of Cometic gaskets, I installed it in my 2000 Chevy late in 2016. In late summer 2017, I started having symptoms that mimicked head gasket failure. I couldn't believe it with the Cometic MLS gaskets, but that sure was what it acted like.

    I tore it down in September and found the gaskets were fine. What I found were cracks between the valves on #1, #7 and #8 cylinders. #7 was the culprit causing the symptoms (pressurizing the cooling system and pushing coolant out and eating coolant). These heads were new in 2012 from GEP (Optimizer heads) purchased through Peninsular Diesel and only had 33,000 miles on them. I contacted them and was advised that they would not help because they were closing down the business. What a disappointment.

    After much research, I purchased a new set of P400 heads from GEP through Leroy Diesel. I picked them up directly at the plant in Franklin, OH. These are the latest and greatest 6.5 heads available. I hope they last. I just got the truck running again yesterday.

    If you go back to the article (the second in the series) that I wrote in 2005 for TDP, you will find a good engineering discussion on compression ratio, cylinder pressure and mep/p3.

    As I will not build one of these for performance or towing without splayed main caps, I will now not build one without Cometic gaskets either.

  13. #13
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    Ft. Wayne, In.
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    Default

    Ron,
    Glad to hear from you again! I sure hope everyone came out alright from the accident.
    Keep up the good work with the 6.5s and keep us in the loop!
    dave
    Dave, N9LOV
    Member #242
    Dave's Diesels:
    Sold June, 07 '82 1/2 ton 4X4;340k miles
    '97 2 Dr Tahoe, Intercooled,
    Kennedy ECM, 4" Exhaust
    '02 GMC

  14. #14
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    GOOD TO SEE YOU Ron

    I used a set of Cometics in a 6.5 that was done right with the decks machined and heads were new.

    Lasted a year and the gasket on the RH side started leaking.

    Not sure what caused it, but it was obvious what had happened.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  15. #15
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    Hey RJ! Good to see you back.

    Hopefully the k-line sleeve treatment to the water ports between the valves will keep my heads from cracking/leaking. Alas, there was some indication that I may have had a leaker also. As soon as I can get a free moment to disassemble them, I can get them to the shop and have them pressure tested.
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  16. #16
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    Just for more info pertaining to heads....

    I have cut several gm & gep heads apart and have posted pics on other forums and can post them here if anyone wants...

    Also I have cut brand new P400 heads apart also, ( p400 heads are close to 1K each), and I have found they ARE NOT the same casting's, I have the pics to show the mold was changed and their is more material INSIDE the cooling area in certain places and have been redesigned internally, thicker head surface, and many other differences I won't go into... I also can post those pics, they have the same casting numbers & markings except the foundry mark...

    I have a set of P400 heads that have the large exhaust valves installed and are highly ported...

    The P400 heads are worth the cost, they are not regular 6.5 heads...
    1993 Chevy K3500

    owner - Twisted Steel Performance

    porting, ceramic & powder coating

    like us on Facebook

  17. #17
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    I put a set of P400 heads on my Dahoooooley the last go round when I scared up the Bare GEP BLOCK (lONG STORY THERE)

    I gave the truck to my son in law after we got it back together and he runs the crap out of it.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  18. #18
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    Quote Originally Posted by sctrailrider View Post
    Just for more info pertaining to heads....

    I have cut several gm & gep heads apart and have posted pics on other forums and can post them here if anyone wants...

    Also I have cut brand new P400 heads apart also, ( p400 heads are close to 1K each), and I have found they ARE NOT the same casting's, I have the pics to show the mold was changed and their is more material INSIDE the cooling area in certain places and have been redesigned internally, thicker head surface, and many other differences I won't go into... I also can post those pics, they have the same casting numbers & markings except the foundry mark...

    I have a set of P400 heads that have the large exhaust valves installed and are highly ported...

    The P400 heads are worth the cost, they are not regular 6.5 heads...
    Why I opted to drop $2100.00 to get a set.

    They also have hardened valve seat inserts.

  19. #19
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    Quote Originally Posted by ronniejoe View Post
    Why I opted to drop $2100.00 to get a set.

    They also have hardened valve seat inserts.
    Yep, and they have a lot more than that going for them... They really did their home work with the P400, different rods, pistons, pins,valves have a swirl inducing cut on the back side, etc..nothing inside the motor will interchange except maybe the crank & cam, and even the cam isn't the same grind....
    1993 Chevy K3500

    owner - Twisted Steel Performance

    porting, ceramic & powder coating

    like us on Facebook

  20. #20
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    Quote Originally Posted by sctrailrider View Post
    I have cut several gm & gep heads apart and have posted pics on other forums and can post them here if anyone wants...
    Raises hand for pictures…
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

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