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| EBI347 |
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you need the larger 78 cc chambers if you want to run ulp not pulp or want to add boost later
just means more timming to make up for the lower compresion just like std factory engine static compression mean little when u r modifying engines its the dynamic that makes the diffeance with differant cams and so on and for 363 78 may be just alittle bit big but 58cc is too small and will nedd lot of timming taken out to help with detonation wont if you want to run c16 all the time here is a question whats the factory 351 efi chamber size any one know?? 
_________________ MY CAR PLZ TAKE A LOOK forums/xtt909-update-t66227.html |
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| EBI347 |
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dude without getting and exact deck height i calucate about 10.76 to1 comp thats with the 78 cc heads and with a 6.5c+ dome and the cam u are using if u use the 58 cc it will be about 13.8 to 1 WAY TOOO HIGH for pump petrol
_________________ MY CAR PLZ TAKE A LOOK forums/xtt909-update-t66227.html |
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| Steady ED |
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{USERNAME} wrote: you need the larger 78 cc chambers if you want to run ulp not pulp or want to add boost later just means more timming to make up for the lower compresion just like std factory engine static compression mean little when u r modifying engines its the dynamic that makes the diffeance with differant cams and so on and for 363 78 may be just alittle bit big but 58cc is too small and will nedd lot of timming taken out to help with detonation wont if you want to run c16 all the time here is a question whats the factory 351 efi chamber size any one know?? hes talking about either going with a dome piston and larger chamber or dished/inverse dome piston and smaller chambers, for the same comp ratio (approx. 10.7:1) i dont know which is better, it seems to me like one of those things where every man and his dog will have an opinion, and you might not find the right one on the internet! maybe a phonecall to whoever you have lined up to build the motor?
_________________ ED XR8 Sprint - S-Trim, V500, 249rwkw |
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| EBXR8380 |
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It seems 62 cc heads and slight bowl in piston works best with good quench.
The bowl in piston close to mirror finish to heads as in TFS pistons... High compression or boosted ?? It's best to have the thickest head deck to prevent head bowing / lifting on high h.p..
_________________ As in ZOOM 126 edition |
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| millard455 |
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well i like the idea of being able to swap the heads for a set with 72cc chambers later on down the track to drop the comp ratio if i decide to add a little boost.
so after looking at what other options i could find i found this, http://www.jepistons.com/Catalogs/Autom ... _flat.aspx part no, 232472 with 58cc chambers i would end up with roughly 11:1 comp ratio. now ive never put anything apart from 98ron fuel in this car so thats not an issue. so what does everyone think, better of doing it this way? thanks everyone.
_________________ EL XR8 SERIES 2, 5SPD, HOT CHILLI RED, 200 ODD RWKW OF V8 FUN AND GAMES |
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| BOTTLEDUP |
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Did this build ever eventuate? Curious to hear how things went.
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| XR9UTE |
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I'd go the 185's myself. here's a coupla basic simulations...
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