2270(or so) Build |
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2270(or so) Build |
yeahmag |
Jan 8 2021, 12:47 PM
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#1
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Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
I'm starting to get the case(s) machined and inspected and parts ordered for my next generation engine. The car is mostly used for autocross.
78x96 96mm piston with 22mm wrist pin (stroker) 5.4" Type 1 Rod, 22mm wrist pin WebCam 86b/86c David Finch heads (from Len Hoffman many moons ago) 9.5:1 CR running on 91 octane pump gas CB Dry Sump (heavily modified) or Thorsten Piper dry sump pump Front mounted oil cooler There are a few crank options out there now: * DPR offset grind Type 1 journal * AA Performance Forged Type 1 journal * FAT Performance Forged Chevy journal I've read about a few 80mm DPR cranks breaking, so I was planning on staying under 80mm as I like the car to be able to rev. I was considering Chevy journals for ease of assembly, but the two cranks I've read about breaking were 80mm/Chevy journals. Is there any new information on cranks out there? Any input on the config? |
Mark Henry |
Jan 9 2021, 02:08 PM
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#2
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Longevity you want the 78mm with T1 rod journals, less crank flex with the bigger journals. I run DPR, you cant beat Swedish steel of the OE crank. China cranks have soft journals but I have used them in the 78mm/T1 rod, racing I'd likely tear down the block each season, where you might go longer with a welded crank.
80mm cranks flex, but there's no replacement for displacement, so if you have a big budget and you can afford engines go for it. If you need the engine to last longer you want the T1 journal. Clearanced CB rods stock T1 or 5.4" I still prefer the EMW KB pistons. Heads need dual springs, retainers, keepers and Manton pushrods. 9.5CR is really pushing it, I'd aim for 9.2-9.3CR. I've used the same cam on several builds, you need reduced base circle. Big duration, good for carbs but almost no vacumm signal for a MAP sensor, so ITB FI has to run in AlphaN (TPS only), which is a pain in traffic but no issue on the track. Issue with the dry sump pumps is the fan in the way. Personally I'd run a 30mm schadeck done full flow, steel cover, tuna can and a big accusump. One of the best mods for a race car is a big ass pipe running air from the front end and dumping it into the fan. |
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