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| Stroker 170? https://slantsix.org/forum/viewtopic.php?t=14115 |
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| Author: | argentina-slantsixer [ Wed Aug 24, 2005 6:28 am ] |
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whad'you know... actually reading makes the diffrence... I thought that panic was pointing out the fact that less CR ratio is better (wich I supossed to be the other way round and it is) Is there any place I can get 198 connecting rods? I want to use some newer hypereuthetic turbo pistons and pin holes are way up than my present pistons... I thought I may go with 198 rods. |
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| Author: | Doctor Dodge [ Fri Aug 26, 2005 5:18 am ] |
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Quote: The 1.93 rod ratio with the 7" rods is like Formula 1 spec, supposedly 2.0 is ideal, I'm told, although some OEM Hondas are only around 1.48
If you use a 3.125 stroke (170 crank) in a tall block and the shorter 2.2 piston, you would need a 7.44 to 7.5 con rod to get in the 8.5 to 9.5 compression range. (flat top piston)What would be the rod ratio be with a 170 crankshaft in a 225 block, assuming you could find custom pistons/rods to allow for the OEM compression height ? No reason to do destroke a 225, just wondering what the numbers might be. The "stroker" 170 is a compact / light weight engine combo but it is still small, displacement wise. The 4.5 in stroke "tall block" is a real low-end torque engine combo. I have run both of these combinations and they are proven to work but have little advantage over a well built 225, especially a "long rod" 225. DD |
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| Author: | Tom Drake [ Fri Aug 26, 2005 7:05 am ] |
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Doug - Didnt you run a 250ci stroker motor? How did it compare rpm and hp wise to the others. I imagine the stroke lowered the rpm rnage but by how much? Tom |
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| Author: | MJF [ Wed Dec 28, 2005 6:29 am ] |
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Hmm... I was thinking... Partly because of Finnish laws, I "need" to use 170 block in my turbo project. So why not stroke it. With my Carrillo 5.932 rods, the rod/stroke ratio would be about same as stock 225. I could use Nissan pistons, which are much shorter and lighter than stock pistons. Then add 20PSI boost and see what happens 
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| Author: | Doctor Dodge [ Wed Dec 28, 2005 10:46 am ] |
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A stroked 170 is a nice combination, as long as you have a use for it. (small car or a racing class it "works" in. The trouble I find is that few people out there can tell the difference between a "short" 170 and a "tall" 198-225 block, all they see is tht you are running a SL6 so you may as well go with the most displacement you can get. As for a 4.5 x 3.485 stroker (or 3.503 bore) you can get into the 260 CID area. That is about max for a SL6 without resleeving the bores. DD |
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| Author: | mcm95403 [ Fri Dec 30, 2005 7:51 am ] |
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Looks like everyone missed the part about the 170 stroker weighing 50 pounds LESS than a 198/225. Also, using a 6" rod gets you a 1.648 rod ratio. Also, as has been pointed out in the past, the slant head was designed for the 170 size originally, so the port and valve sizing is better suited to the smaller engines. Bumping up a 225 to a 260 would make a good torque engine, but it's going to be straining for air in the higher rpm ranges compared to a smaller engine. The smaller engine with the shorter stroke can also use higher compression more effectively with less ping. There is also the possibility of using a 225 cast crank that is welded and reground in place of the 198 crank. This cuts down more engine weight, as well as dropping reciprocating mass for better throttle response. By using small block Chevy rods designed for the small journal (2") crank pin, very little welding would be required to get the right stroke length - just .292 or slightly more than a 1/4". You also end up with a 1.86 compression height piston to get zero deck - which is completely reasonable. So, in a light weight car the 210 would be a good choice for a free reving "sports car" type engine. I've actually been putting a lot of thought into this the last few days since it seems that an aluminum block is not going to come my way and this would get me down to almost the engine weight I was wanting in the first place. Thanks, Marc www.marcmedina.com |
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| Author: | mcm95403 [ Fri Dec 30, 2005 8:07 am ] |
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Speaking of which, I'm placing an ad in the Parts Wanted section for a 170 block and cast crank if anyone in the NorCal area has something available................... Marc www.marcmedina.com |
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| Author: | Doctor Dodge [ Fri Dec 30, 2005 9:49 am ] |
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Marc, You can't get a 225 (4.125 stroke) crank into a 170 block, the carank pocket area is to small. Getting the 198 (3.64 stroke crank into a 170 takes a good amount of grinding work. I have 170 and Alm. 225 engines available if you need one. DD |
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| Author: | Mr. D-150 [ Mon Jan 02, 2006 9:21 am ] |
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Quote: It has been done. Pretty sure Doc Dodge has one. But for the life of, I don't see a lot of reason to do it. If you take a 198 motor and bore it the same as the 170, you get the same cubes. A 225 is bigger yet, with a comparable bore. There is a small weight saving with a 210 low blck as compared to a 210 tall block. The only other reason, I can see to use the 170 block, would be to tell everyone you are running a 170, when you really have much more (can you say cheat).
Since most folks don't know the RG block is one inch taller than the LG, how would they know the difference anyway?  I mean you just stomped their ( V-8/ ricer wanna be {pick one}) all over the place anyhow.But one advantage to the LG block is cylinder wall support, less flex = more power. I'm thinking on the feasibility of a 225 LG stroker combo for that reason. With a low CR, some pretty high boosts from a super / turbocharger could be real fun on Saturday nights . . .  Budd |
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| Author: | DionR [ Wed Jan 04, 2006 11:05 pm ] |
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How about a DE-stroked 170? I've been trying to come up with a cheap way to build a /6 with some off the shelf pistons and rods. Best if been able to figure out is destroke the 170 crank to 3.00" and use 2.2 turbo pistons and rods. Displacement is 168 (I think) so you don't loose much. I figured the journal in a journal idea would make this work, but I suspect that you would still need a fair amount of welding on the inside to get enough metal to make the second journal work. The ONLY reason I can see to do this is to hit it with a bunch of boost and spin it to 7 grand or higher. Which is exactly what I would love to try. Ah, the plans of mice and men.
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