Slant Six Forum :: Stroking a slant

Doug's a good one to answer this. I don't think you can use both; you'd push the pistons right out the tops of the cylinders!

My question is why do you want the long rods and a stroked crank?
Tom

I have done both and it is expensive and a "pain" to keep the compression at a reasonable level.

Tom's statement is a good one, "why?"

The stroking of the crank off-sets the advantage of the long rod. (rod ratio) If you want displacement and low end grunt, go the stroked crank route. If you want more high RPM & HP, use the long rod combo.

Both set-up give you the lighter pistion that ipistong reason why these "special" engines run well. (dished pistions must pistonsor compression gets into the 12 to 1 range)

One problem with more stroke on a real short piston (with the thinner ring packs) is that piston stability and ring seal starts to become a problem, especially at higher RPMs. A nice rod ratio helps control this problem.
DD

Would a set of hypereutectic (sp?) pistons be okay, or would true forged be better?

Quote:

Would a set of hypereutectic (sp?) pistons be okay, or would true forged be better?

If you're never going to run nitrous or forced induction, I'd prefer hypereutectic as they're more dimensionally stable and you can run tighter piston tolerances. (hypereutectic is more brittle than forged, thus a screwup on nitrous or forced induction may shatter them)

Do you mean there's the possibility that they'd (pistons) rock badly?

I guess what I'd like to do is find a good solid rolling F.E.D. chassis and power it with that stroker slant. I thought it would make for a good combination of light weight and decent power, plus it wouldn't be a cookie cutter ride. What I'd like to do is start out with a dual two-barrel (or four barrel) on gasoline with a ported head and the other usual mods, and move up from there. Eventually I hope to put the stroker together with Hilborn fuel injection on alcohol.

Didn't someone try running a blower in a late 60's 'cuda a few year ago? How did it turn out? Was he using a 3-71?

Yes, that was Seymour's buddy Evans up in MN. It was a 4-71 and it worked very well. It did require a lot of special fab and machine work to pull off though.

Author:	Gonzo [ Thu May 25, 2006 9:07 pm ]
Post subject:	Stroking a slant
Has anyone ever built a long rod engine with a welded crank (4.50 stroke)? The way the article read (to me anyway), it sounded like one or the other and not together. Would the extra work and expense be worth it?

Author:	SlantSixDan [ Thu May 25, 2006 9:10 pm ]
Post subject:
Doug's a good one to answer this. I don't think you can use both; you'd push the pistons right out the tops of the cylinders!

Author:	Gonzo [ Thu May 25, 2006 9:51 pm ]
Post subject:
Quote: Doug's a good one to answer this. I don't think you can use both; you'd push the pistons right out the tops of the cylinders! Nuts, I was afraid of something like that! I wonder if you could have a set of pistons made that had the pins high enough to get zero deck height? Or could they end up into the oil rings?

Author:	Tom Drake [ Fri May 26, 2006 8:16 am ]
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My question is why do you want the long rods and a stroked crank? Tom

Author:	Doctor Dodge [ Fri May 26, 2006 8:55 am ]
Post subject:
Quote: My question is why do you want the long rods and a stroked crank? Tom I have done both and it is expensive and a "pain" to keep the compression at a reasonable level. Tom's statement is a good one, "why?" The stroking of the crank off-sets the advantage of the long rod. (rod ratio) If you want displacement and low end grunt, go the stroked crank route. If you want more high RPM & HP, use the long rod combo. Both set-up give you the lighter pistion that is the big reason why these "special" engines run well. (dished pistions must be used or compression gets into the 12 to 1 range) One problem with more stroke on a real short piston (with the thinner ring packs) is that piston stability and ring seal starts to become a problem, especially at higher RPMs. A nice rod ratio helps control this problem. DD

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Author:	Gonzo [ Fri May 26, 2006 11:11 am ]
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Quote: My question is why do you want the long rods and a stroked crank? Tom I thought it would help me get the most out of the engine, but it sounds like it would have been major overkill. With the cost of the welded crank, rods and pistons instead of just the welded crank and pistons, I doubt I could afford it even if the combination did give more power. Quote: I have done both and it is expensive and a "pain" to keep the compression at a reasonable level. Tom's statement is a good one, "why?" I'm one of those "old school" types who believe there's no replacement for displacement, plus I thought a set-up like that would net me more power. Quote: The stroking of the crank off-sets the advantage of the long rod. (rod ratio) If you want displacement and low end grunt, go the stroked crank route. If you want more high RPM & HP, use the long rod combo. Both set-up give you the lighter pistion that ipistong reason why these "special" engines run well. (dished pistions must pistonsor compression gets into the 12 to 1 range) Would a set of hypereutectic (sp?) pistons be okay, or would true forged be better? Quote: One problem with more stroke on a real short piston (with the thinner ring packs) is that piston stability and ring seal starts to become a problem, especially at higher RPMs. A nice rod ratio helps control this problem. DD Do you mean there's the possibility that they'd rock badly? I guess what I'd like to do is find a good solid rolling F.E.D. chassis and power it with that stroker slant. I thought it would make for a good combination of light weight and decent power, plus it wouldn't be a cookie cutter ride. What I'd like to do is start out with a dual two-barrel (or four barrel) on gasoline with a ported head and the other usual mods, and move up from there. Eventually I hope to put the stroker together with Hilborn fuel injection on alcohol.

Author:	emsvitil [ Fri May 26, 2006 4:35 pm ]
Post subject:
Quote: Would a set of hypereutectic (sp?) pistons be okay, or would true forged be better? If you're never going to run nitrous or forced induction, I'd prefer hypereutectic as they're more dimensionally stable and you can run tighter piston tolerances. (hypereutectic is more brittle than forged, thus a screwup on nitrous or forced induction may shatter them)

Author:	slantzilla [ Fri May 26, 2006 8:16 pm ]
Post subject:
Quote: Quote: Would a set of hypereutectic (sp?) pistons be okay, or would true forged be better? If you're never going to run nitrous or forced induction, I'd prefer hypereutectic as they're more dimensionally stable and you can run tighter piston tolerances. (hypereutectic is more brittle than forged, thus a screwup on nitrous or forced induction may shatter them) I have hypers in mine. They work well with nitrous up to 150 horse shot. Contrary to the popular belief, they will not shatter. They will however, split in half.

Author:	AnotherSix [ Fri May 26, 2006 8:20 pm ]
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I learned this the hard way. Hypereutectic pistons stay a bit hotter on top. They just don't transfer the heat like the alloys in forged or even stock cast pistons. I used them in a turbo charged car that I had turned up to the limit on pump premium, I had to drop the boost about two psi to get rid of the detonation. It was a new rebuild but the combination was exactly the same as before, the compression was actually lower because of O-ringed head gaskets and a little polishing in the chambers. They are however very durable and you can run them at really tight clearances and this helps the ring seal. If detonation is not a problem with your combo I would choose them over a forging that needed more clearance.

Author:	gmader [ Fri May 26, 2006 8:48 pm ]
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http://www.techlinecoatings.com/article ... rticle.htm I suspect that this might be a good way of helping hypereutectic pistons live in extreme environments. I read an article where they used the basic thermal barrier coating on a number of pistons, and stress tested them with cutting torches. The thermal coating helped them live. The uncoated ones failed. I bet Dan has some good research one way or another on coatings. Greg

Author:	Doctor Dodge [ Sat May 27, 2006 7:52 am ]
Post subject:
Quote: Do you mean there's the possibility that they'd (pistons) rock badly? I guess what I'd like to do is find a good solid rolling F.E.D. chassis and power it with that stroker slant. I thought it would make for a good combination of light weight and decent power, plus it wouldn't be a cookie cutter ride. What I'd like to do is start out with a dual two-barrel (or four barrel) on gasoline with a ported head and the other usual mods, and move up from there. Eventually I hope to put the stroker together with Hilborn fuel injection on alcohol. You have a great project in mind, I would use the stroker crank - more displacement combo if you can get the crank done at a reasonable cost. (FYI 4.440 stroke is the max stroke that takes very little block grinding / notching, 4.5 can be done but takes way more work) Try to keep the piston clearances tight to reduce piston rocking and keep a good ring seal, this is an issue with long stroke engines but it is not a "show stopper". The "long rod" 225 is also a very good engine combo, either one of these engine combos would work well for you project. As for pistons, get the strongest ones you can afford, when power levels (compression) get high, pistons are the first to "fry". I tend to crack / break pieces off the cast and the Hyper material pistons, the forged pistons tend to "smear" in the bores. DD

Author:	Gonzo [ Sun May 28, 2006 5:56 pm ]
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Good grief, forged pistons can smear the cylinder walls if they get too hot? It sounds like I'm going to need a really good cooling system, along with letting it run a tad rich, even running alcohol. I don't plan to run nitrous, but I had thought about a blower. Trouble is now we're talking real money, not that this little project isn't expensive enough already! Didn't someone try running a blower in a late 60's 'cuda a few year ago? How did it turn out? Was he using a 3-71?

Author:	slantzilla [ Sun May 28, 2006 7:42 pm ]
Post subject:
Quote: Didn't someone try running a blower in a late 60's 'cuda a few year ago? How did it turn out? Was he using a 3-71? Yes, that was Seymour's buddy Evans up in MN. It was a 4-71 and it worked very well. It did require a lot of special fab and machine work to pull off though.

Author:	Gonzo [ Sun May 28, 2006 10:38 pm ]
Post subject:
Quote: Yes, that was Seymour's buddy Evans up in MN. It was a 4-71 and it worked very well. It did require a lot of special fab and machine work to pull off though. Well, those 6 injector stacks look pretty cool too. Aren't most (if not all) of the pieces still available, new or used?

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