S4 rotors, 8.5:1, or 8.2:1?
As title, ive heard both.
Officially they seem to be said to be 8.5:1, but seen on a few places, places that should know, that they are 8.2:1. Unless its a typo. Does anyone know for sure? :icon_tup: |
Originally Posted by StavFC
(Post 10233473)
As title, ive heard both.
Officially they seem to be said to be 8.5:1, but seen on a few places, places that should know, that they are 8.2:1. Unless its a typo. Does anyone know for sure? :icon_tup: there is a fair tolerance up and down due to the finishing techniques -- several points of compression is normal in the same engine however the s4 turbo FC will have an intended 8.5:1 static compression the NA will be 9.4:1 the s5 is 9.0 ( turbo ) and 9.7:1 NA and the production tolerance is much more precise the GSL-SE ( 83-85 HB cosmo RESI 13b engine ) is 9.4:1 the rx4 1757 13b rotor is 9.2:1 the 12a rotors are 9.4:1 NA and 8.5:1 for the turbo |
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Along those same lines...
The cast rotors (S4 and earlier) have a tolerance of +/- 0.3 CR. So while an S4 TII rotor is officially listed as 8.5:1, it could be somewhere between 8.2:1 and 8.8:1. As mentioned, the machined rotors found in S5s and later were more precise and had a tolerance spec of only +/- 0.06 CR. https://www.rx7club.com/attachment.p...1&d=1285368214 |
as RotaryRocket explained, the cast design of the s4 means a wider manufacturing tolerance for compression ratio. But the s4 rotors are also considered to be stronger in high detonation situations or extremely high horsepower setups. I know my s4 rotors have taken some punishment. Occasionally you will read about people having "dents" in the s5 and s6 rotors from detonation... I don't think this difference in strength is a big deal for most applications though.
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Great info :)
So, how do you calculate compression ratio on a rotary? On a piston engine I know how, and once again it will be measuring the dish volume, but how do I known what dish volume equates to what? Does anyone have the dish volumes for the various standard compression ratios? Should be able to work out most ratios from there. |
try posting in "rotary car performance" about that
also PM rotarygod , he might know |
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