Planning the foundation
So, I have this pile of parts in the basement, I need a plan for how I'm going to move from that to a running engine. Let's define some goals:
- Durability. I'd like to get 5 to 10 years worth of autocrossing and track events out of this build.
- Power level. Everything I've read says that a Corvair engine that stays under 6500 RPM will last a long time. To a certain extent, that limits other choices which will affect the overall power level. Let's say I'm trying for 160 to 180 net crank HP. That may not sound like much, but remember that 140 only makes 121 HP net, so a 160 HP net engine is a 30% increase over stock, 180 is 50%.
- Budget. I'm willing to spend for required items, but really trick stuff - custom pistons, fuel injection, etc., are out. Let's say that counting the parts I already have, and allowing zero for my labor, the budget is around $4000 total. If I focus on the base engine, then hopefully I can bolt on other parts as time and money allow.
- Rules. I can't really afford an SCCA SM legal engine, so I'm staying within the SP rules. That means the internals have to match one of the stock or Stinger configurations, within the limits of available parts, and there are many available "bolt on" mods. I'll be building a copy of a Yenko Stage III engine, plus any allowed SP mods.
Alright, those a pretty broad goals. To achieve the durability and power, the first step will be on the shortblock. I'll be reviewing other sources, but roughly the list looks like this:
- Blueprint oil system, enlarge passages as suggested in performance guides, smooth passages.
- Remove flash to promote drainback to the oil pan.
- Baffle oil pan. I have a system in mind using an Offenhauser deep pan. The Otto parts pan and baffle would be similar.
- Pin crank. Crank gears sometimes will turn on the crank.
- Select cam to be close as reasonable to Yenko Stage III "short track" cam. These cams were approximately 280 degrees advertised duration and .450" lift. There are several similar grinds available (e.g. OT-20). Use Source deep dimple lifters.
- Degree cam and install Otto Fail Safe gear.
- Pistons and rods are Clark's reconditioned rods with TRW forged pistons balanced set.
- Bearings are new, but check using Plastigauge anyway.
- Convert PCV to modern "cross flow" system.
Alright, that's it for now. I think this is a pretty good example of what a performance Corvair engine should look like, but there may be a few items I've missed, comments are welcome.
Bryan Blackwell bryan@skiblack.com
Bryan's Corvair Autocross Page
Corvairs: '61 Lakewood, '64 Greenbrier, '65 Corsa, '66 Corsa
'69 Road Runner, '97 Ford F-150, '99 Neon R/T
"Why do something if you're not going to obsess about it?"
- Durability. I'd like to get 5 to 10 years worth of autocrossing and track events out of this build.
- Power level. Everything I've read says that a Corvair engine that stays under 6500 RPM will last a long time. To a certain extent, that limits other choices which will affect the overall power level. Let's say I'm trying for 160 to 180 net crank HP. That may not sound like much, but remember that 140 only makes 121 HP net, so a 160 HP net engine is a 30% increase over stock, 180 is 50%.
- Budget. I'm willing to spend for required items, but really trick stuff - custom pistons, fuel injection, etc., are out. Let's say that counting the parts I already have, and allowing zero for my labor, the budget is around $4000 total. If I focus on the base engine, then hopefully I can bolt on other parts as time and money allow.
- Rules. I can't really afford an SCCA SM legal engine, so I'm staying within the SP rules. That means the internals have to match one of the stock or Stinger configurations, within the limits of available parts, and there are many available "bolt on" mods. I'll be building a copy of a Yenko Stage III engine, plus any allowed SP mods.
Alright, those a pretty broad goals. To achieve the durability and power, the first step will be on the shortblock. I'll be reviewing other sources, but roughly the list looks like this:
- Blueprint oil system, enlarge passages as suggested in performance guides, smooth passages.
- Remove flash to promote drainback to the oil pan.
- Baffle oil pan. I have a system in mind using an Offenhauser deep pan. The Otto parts pan and baffle would be similar.
- Pin crank. Crank gears sometimes will turn on the crank.
- Select cam to be close as reasonable to Yenko Stage III "short track" cam. These cams were approximately 280 degrees advertised duration and .450" lift. There are several similar grinds available (e.g. OT-20). Use Source deep dimple lifters.
- Degree cam and install Otto Fail Safe gear.
- Pistons and rods are Clark's reconditioned rods with TRW forged pistons balanced set.
- Bearings are new, but check using Plastigauge anyway.
- Convert PCV to modern "cross flow" system.
Alright, that's it for now. I think this is a pretty good example of what a performance Corvair engine should look like, but there may be a few items I've missed, comments are welcome.
Bryan Blackwell bryan@skiblack.com
Bryan's Corvair Autocross Page
Corvairs: '61 Lakewood, '64 Greenbrier, '65 Corsa, '66 Corsa
'69 Road Runner, '97 Ford F-150, '99 Neon R/T
"Why do something if you're not going to obsess about it?"
posted by Bryan Blackwell | 11:24 AM
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