Naturally aspirited boxer tuning?
26 December 2009, 04:52 AM
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Naturally aspirited boxer tuning?
I was wondering if anyone has any experience with n/a boxer engines, what can I do with a v9 STi bottom end to get it up to nice spec, which heads/cams..etc?
26 December 2009, 06:56 AM
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I'm not expert but the good old N/A route is polish and port + cams. Not sure that a turbo engine is a good start point as the head flow requirements are different to NA engines (exhaust side particularly). Also the compression ratios are totally different.
26 December 2009, 07:32 AM
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Have a chat with David at API, but as you have a confusion over STI engines (there was no version 9 and new age sti engines are very confusing due to the several different versions available), plus its severe overkill, and its always best to stick to a similar/same engine.
Do not expect big gains though, you wont get much out of a NA engine power wise.
Tony
Do not expect big gains though, you wont get much out of a NA engine power wise.
Tony
26 December 2009, 08:31 AM
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TEG have built a couple of N/A engines for the road rally guys (as they are no longer allowed turbos).From memory both were 2.5L bottom ends.One had V3 RA heads, ported polished etc and the other had n/a heads with some high lift/long duration cams.We made a ram air type system air box feeding through the turbo bonnet scoop, fitted Simtek ECUs (modded for n/a operation) and made 195 BHP (std cam) and 210 BHP (high lift) on a 10% meth mix.
Steve
Steve
26 December 2009, 01:01 PM
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TEG have built a couple of N/A engines for the road rally guys (as they are no longer allowed turbos).From memory both were 2.5L bottom ends.One had V3 RA heads, ported polished etc and the other had n/a heads with some high lift/long duration cams.We made a ram air type system air box feeding through the turbo bonnet scoop, fitted Simtek ECUs (modded for n/a operation) and made 195 BHP (std cam) and 210 BHP (high lift) on a 10% meth mix.
Steve
Steve
Do you know what torque they made?
26 December 2009, 01:10 PM
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Yeah i'm aware that a higher compression is more favourable, I was thinking of using ported&polished sport heads, high lift cams and getting the block skimmed to increase compression.
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26 December 2009, 01:19 PM
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Can't exactly remember torque figures (will pull up graphs when I'm back in dyno after New year) but was in the region of 180 - 200 ft lb with quite a nice flat profile from 2500 to 5000 RPM. We used CR around 11.0:1 due to problem getting good fuel on night rallies at the fuel halts.If fuel wasn't an issue I would try 11.5 -12 CR.
Steve
Steve
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