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Discussion Starter #1
what is the biggest displacement gotten from overboring the 5m/6m/7m engine? what was the gain anyways.

Kyle
 

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Not directly addressing your question, but the price/performance ratio of stroking or overboring the engine is almost always lower than turbocharging from what I've read.
 

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Discussion Starter #3
well i was thinking more along the lines of boreing and then turbocharge it.

does the 6m head have hydraulic lifters?

how much did it cost phil to do the ceramic-metallic coating on his engine anyone know?
 

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Its not worth overboring on the M series motor. The largest factory O/S piston is +1.5mm which ends up with a gain of like 2-3 cubic inches. And yes the 5/6M head has hydraulic lash adjusters. They aren't don't really function like the lifters that you see in pushrod engines though.
 

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It was a few years ago but seems like I recall it was something like an extra $100 altogether for all the ceramic coatings combined, piston tops, chambers, valves, and exhaust ports.

Phil D.
 

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Discussion Starter #6
would you say it was worth it to do it?

what is the real reason behind it? to heat protect the parts from the increaced heat caused by the turbo?
 

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DKJones96 said:
would you say it was worth it to do it?

what is the real reason behind it? to heat protect the parts from the increaced heat caused by the turbo?
Something like that. I have no idea if it was worth it or not, but what the hey, my list of mods is longer 8) Actually, I have a machine shop guy that I trust and that was his suggestion.

Phil D.
 

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wouldnt ceramic disipate the heat more poorly than plain metal? I could be wrong, but it seems like it would cool off slower.
 

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No == ceramic is awesome at heat dissipation. That's why F1 cars run ceramic brakes.
 

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well, if i recall, a 7m bored 2mm over make ~3.2L 91mm stroke x85mm bore. anyway, its been done, but i wouldnt do it unless the car is gonna be used for racing only as you may crack a few blocks if running high boost.
 

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never mind, i found an online displacement calculator and 85mm bore and 91mm stroke is 3098c. however, the 85mm bore and 86mm(5m) stroke is 2928cc .

heres the link to the displacement calculator. has a setting for metric and sae. pretty nice tool.

http://www.web-cars.com/math/displacement.html
 

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Even if you could get a worthwhile displacement increase with a 2mm overbore, you'd be nuts to do it. Later M series engines already have a very small bore spacing, and that's part of the reason for their infamous headgasket problem. Overboring it is only going to make the problem worse!
 

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well, thats what i said, i wouldnt do it unless it was race only, and id be worried about blowing more then a hg. anyway, there was a guy that bored his 5m 2mm over and only problem he had was it went lean on the dyno and took out 4 forged pistons. and with 4 melted pistons made ~300rwhp. ill try to find the link to his site. it can be done but i wouldnt recomend it.
 
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