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big memeber
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Discussion Starter #1
high compression pistons.... god or bad?? i dont know what i want to do right now and there was a set on e bay that wasnt for too much but i dont know what i should do
 

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missing El Polo Loco...
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2,165 Posts
depend on the end product you're looking for. For a normally aspirated engine, it definitely is good, but might make the engine less drivable around town. It's depends, how high a compression is considered high to you?
 

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Golden Member
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mate either go 10.5 or all the way with lbj... (hello 12.9:1 ! )
 

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Golden Member
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lol, an american president ! it was his election motto, "all the way with LBJ" !
 

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Incognito
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wait, isnt he turboing? I would not like to see an engine with 12.9:1 comp go under boost... that would be seriously ugly and the engine would probably last about an hour under boost conditions.
 

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Golden Member
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turbo? really? didnt kno ... or see any reference to it...

if so, even 10.5 is suicide... unless its running on bloody good fuel...

i think WRC rally cars have like 10.5 or 11:1 compression or something like that, whilst running 20+psi boost !!!

CRAZY ! :D

cheers

joe
 

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big memeber
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315 Posts
Discussion Starter #9
i did a little more thinking about it and i dont want to go with high compression pistons. i really want a turbo and it would be like fighting each other so i guess high compression is out of the question
 

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Die Trying
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8,357 Posts
^^ very good
a little search will go a long way

for a regular street driven car, remember this rule of thumb:
low compression for boost
high compression for n/a, or even a little juice
 

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Incognito
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6,134 Posts
the reason WRC cars can run high boost and high comp is because those engines are broken down and cleaned for every race, not to mention they have several specific cars for each race.
 

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big memeber
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Discussion Starter #12
thanks cthunder i was just about to ask why they could run more boost with high compression pistons
 

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A-arm brace man
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392 Posts
GO Turbo!! screw NA:D
 

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mygirlsalty said:
if you did na 10.5:1 you would need to run premium gas. just my .02.
^^yeah true, here u would use 95RON premium, which is only what 2-3 cents more per litre.... at least u wouldnt need 98 octane (shell optimax or mobil synergy or some crap) that can be 2-30 cents / litre more...
 

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felipesaltima said:
i did a little more thinking about it and i dont want to go with high compression pistons. i really want a turbo and it would be like fighting each other so i guess high compression is out of the question

hey yeah definately man, on a street car u def cant do both.... i would think 8.5 to 9:1 would be more appropriate... the lower u go tho, the more laggy it is.. esp if fitted with a big turbo, but on the other hand u can boost more !

depends what u want, i suggest u talk to your motor builder and he shoudl find a sweet spot for your needs...


cheers

joe
 

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cthunder said:
the reason WRC cars can run high boost and high comp is because those engines are broken down and cleaned for every race, not to mention they have several specific cars for each race.
yeah thats true, but on the other hand, they gotta be using some damn good fuel, otherwise the cars wouldnt make it to their overhaul interval at the end of the race :D


edit: even so, dont they still knock and backfire like crazy? i think i saw that on some WRC show and remembered thinking CRAP ! that cant be good... :eek:
 

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Incognito
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oh yeah, those cars run 120 octane minimum... and yes they backfire like crazy, they dont need those special kits to send flames out their tailpipes, because they run really really really rich. Being an auto, having a 3" exhaust, and being 8:1 comp, I really dont have that much lag to speak of. because the clutch plates are always open, I have constant boost... now a manual, it would suck.
 
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