649hp@crank with stock rods, reinforced main caps and VW Beetle forged pistons. Dynoed in 2005
Detonation destroyed one set of pistons and head surface.
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| Author: | the_engineers [ Thu Nov 22, 2012 6:43 am ] |
| Post subject: | Slant Boom |
I'm wondering how Slants fail as you start to make maximum, boosted power. Is it a matter of blowing head gaskets, twisting rods, blowing chunks out of (insert part name here)? What failures have you had/seen? At what power level? |
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| Author: | Gringo Bandito [ Thu Nov 22, 2012 7:19 pm ] |
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I would imagine it's primarily detonation. Overly-lean conditions in one/some of the cylinders. |
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| Author: | CNC-Dude [ Thu Nov 22, 2012 10:44 pm ] |
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Its typically blown head gaskets or melted pistons. Blown head gaskets are common on engines that have 4 head bolts per cylinder once you start applying boost in the form of nitrous or forced induction. The bottom ends in the slant seems to be pretty bulletproof for the most part, and except for just all out insane HP levels, failure in the bottom ends is usually rare. |
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| Author: | Dart270 [ Fri Nov 23, 2012 4:03 am ] |
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These are accurate statements. You need to be above 500 HP before you start worrying about rods, crank, block, if in good shape and/or properly rebuilt/assembled. From what I have seen and experienced, a composite-type head gasket should be good to about 400 HP, with maybe head studs (stock diam) needed but I bet stock bolts are fine too. The one ($6) head gasket I have blown was repeatedly overheated due to fire ring protruding into chamber. >100 drag passes and 6k hard (fun) street miles before it blew. New setup with Permaseal composite gasket and head studs has similar use on it up to about 330 crank HP. Lou |
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| Author: | the_engineers [ Sat Nov 24, 2012 9:44 am ] |
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So, as long as the engine management system keeps me in the right spark and fuel, I'll run out of airflow before I overpower the strength of the block and components? I'm seeing people struggle to flow muc more than 225 cfm, so I'm guessing I'll max out on my build at the 400-450 HP range. |
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| Author: | billdedman [ Sat Nov 24, 2012 11:24 pm ] |
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The robust infrastructure of the slant six engine will take a lot of boost, I think, before it suffers a broken crank, cracked or moved main bearing webs, broken rods (if good-quality aftermarket (K-1, for instance) are used. ARP offers heavy-duty head studs (260,000psi) that will resist stretching, allowing higher boost pressures, along with O-ringing the block to prevent blown head gaskets. I know off two guys who have run 30psi of boost without parts failure. I wonder if 40 psi might not be feasible. Tom Wolfe and Ryan Peterson both make around 500 hp on 25-28 pounds of boost, on gasoline. I can imagine a 600hp motor on alcohol with main bearing supports, a filled block, O-riged deck surfaces and a turbo of sufficient flow charcteristics. Am I dreaming? |
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| Author: | Dart270 [ Sun Nov 25, 2012 3:43 am ] |
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630 HP @5200 RPM (@ crank) and over 700 ft-lbs is the documented record for HP from a gasoline, street driven Slant 6. No crank girdle or extreme block strengthening. I think it is partially filled, though. K1-type rods, copper gaket w/o-rings and studs up top. 21 psi max boost, and he said it was just over 600 HP with 16-17 psi. Cameron Tilley in Sydney, Australia. It is worth the plane ticket down there to meet him and get a ride in his '66 VC Valiant... Drives and sounds like a grandma's car until you get into it. I am wondering if Will Burns will exceed these numbers in 2013? Lou |
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| Author: | billdedman [ Sun Nov 25, 2012 11:38 am ] |
| Post subject: | |
Lou, That's really interesting... thanks! These slants are just amazing with regard to their strength and ability to absorb abuse. All that from just 4 main bearings and 4 head bolts!!! All through the magic of turbocharging.... |
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| Author: | Dart270 [ Sun Nov 25, 2012 12:53 pm ] |
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Bill, If you search "tilley" on this site, you should get a bunch of hits. He does not post himself, but it is all for real. Adjusted surface area (bore area), our 4 head bolts are fine relative to smallbock V8s, probably all V8s in fact. Looking forward to your runs this year! Lou |
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| Author: | slantzilla [ Sun Nov 25, 2012 12:58 pm ] |
| Post subject: | |
Quote: I would imagine it's primarily detonation. Overly-lean conditions in one/some of the cylinders.
This right here. /\A bad tune-up destroys way more parts than good horsepower. |
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| Author: | MJF [ Mon Nov 26, 2012 6:02 am ] |
| Post subject: | |
649hp@crank with stock rods, reinforced main caps and VW Beetle forged pistons. Dynoed in 2005 Detonation destroyed one set of pistons and head surface.
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| Author: | billdedman [ Tue Nov 27, 2012 8:00 am ] |
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Quote: 649hp@crank with stock rods, reinforced main caps and VW Beetle forged pistons. Dynoed in 2005
Wow; that is a bunch of horsepower!!! Detonation destroyed one set of pistons and head surface.Can you let us in on where we might be able to view some pictures of that intahe sysstem, and header? I'd love to see wwhat it takes to make that kinde of power from a slant 6. Was that on gasoline, alcohol, or??? And, what kind of cam specs were used (duration @ .050"-lift) and what was the redline? Did it detonate because it went lean, or was thwre too much spark advance for that amount of boost (and, what was the boost, to make that kind of power???) I'm not going to try to build anything like that, but it's so impressive, I couldn't help but be curious abut all that stuff, Thanks for sharing! Bill. in Conway, Arkansas |
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| Author: | MJF [ Wed Nov 28, 2012 12:01 pm ] |
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Pump fuel. There was 3 electric fuel pumps and one failed, that´s why it went lean. I´ve tried to search cam specs, but nobody remembers exactly and no papers have been found, not from owner, cam designer or cam grinder  It was something like 290 degrees, but not for sure. 11,55mm lift for sure. Redline with 225 was ~6000, 198 revd happily much higher with otherwise same setup. Triple side draft carbs and header, pics are here: http://koti.mbnet.fi/trc/technic.htm Full potential of the engine was never seen at strip, becouse of several difficulties with torque converter, transmission and rear end.
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| Author: | Dart270 [ Wed Nov 28, 2012 3:03 pm ] |
| Post subject: | |
Impressive engine and car. I am thinking Will Burns' turbo setup will be in that HP range and should reach dragstrip potential in a ~ 2300lb racecar = FAST. Lou |
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| Author: | Doc [ Wed Nov 28, 2012 3:54 pm ] |
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We have seen SL6 oil pump drive gears fail at just about every power level so don't overlook the "small stuff". DD 
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