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SPI 6000+ HEAD


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#1 Ngardner



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Posted 19 December 2019 - 12:43 PM

Im sure this topic has come up once or twice, but search didnt help,   I recently got a pretty good price on a spi hi comp head for an 800 etec. 


anyone have experience with this specific brand head, or other high compression heads, Good, Bad, ugly? 

also this sled only has a y-pipe and hps trail can for engine mods.  those with experience with the head and y-pipe, did you find the need for fuel controller? 

how as plug cooler and piston wash?   

any issues with knock/pinning closer to 6000ft?


please refrain from commenting if your comments consist of . "there junk",  "not worth the money", "Waste of money".  or anything like that,  its already bought so save it!!  



thanks in advance  Nick

#2 ctdls


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Posted 22 December 2019 - 09:48 AM

Raising compression improves the burn so no additional fuel required, remember power drops approx. 3% per thousand feet. Reduced air pressure & oxygen as you gain elevation, so depending on much they raised the compression ratio highly unlikely you will have knock issue's. I've often wondered if running low octane in elevation is beneficial, some high elevation riders panic when they can't get premium & are perplexed when I tell them it isn't necessary @ 6k'/ft. Then we have the guys that think running race gas improves the performance of a stock compression engine  :)


I've no experience with the head you purchased, I have tried other aftermarket heads & found in most cases they were great is short duration. Most did not hang on for sustained WOT in the mountains, re machining the stock squish bands & decking my not give bragging rights form a dyno report however sustainable rpm on the long grinds.


There is good reasoning to wide squish bands with a stock cylinder head.

Edited by ctdls, 22 December 2019 - 10:26 AM.

#3 slimjohnson



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Posted 22 December 2019 - 10:17 AM

I have used spi heads with positive reults, add a bondi air box and a good set of reeds and it will really open up the 800 etec.

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