My engine build is coming to an end. I dropped by the shop last week to talk camshaft timing/setup with the builder.
A couple of queries. He checked the duration of the cams that were bought by the previous owner (many many years ago) which I'd always assumed were the 260/260 kit. He found the actual duration to be more like 263/256. This is a guide as the measurement accuracy is +/- with the closest being 262/258 and the worst being 265/254. The intake was consistently a little higher than the exhaust though which reading up is not normal on turbo cars.
I understand if you do split timing on a turbo car it should be the exhaust side that's slightly higher rather than the intake. I can only think it's to help low/mid range that you might use for a rally car rather than the max HP you look for on a drag car? To be honest it's close enough to what I want on a car to not worry about though I'd appreciate people's views.
More concerning is the cam timing. For my last engine build (only "many years ago") I'd simply followed Piper's guidance for 110/110 (Inlet/Exhaust timing) given on their website:
http://www.pipercams.co.uk/pipercams/www/product_nav.php?type=C&cat=CM&man=16&engine=222
Double checking on the internet I understand the OEM cam timing is 110/120 for our SR20DET.
Tomei recommend a 110/115 setting for all their camshafts on our engine
HKS recommend a 108/114 for all their camshafts
My concern is Piper developed the cams for the Primera SR20, as this is the only other application referenced on their site, and lazily transferred the settings over for the GtiR?
I know that to tune the cams in I ideally need a rolling road but I want a decent starting point. On my last map I had to do some abnormal mapping for idle and cruise that I'd not seen on other cars. A 10deg shift on the exhaust cam is pretty significant if Piper have just done a copy and paste error!!!
What other timing suggestions are given by manufacturers for our cars. As with the Tomei and HKS recommendations, I'd expect most to be in a similar range?
Cheers,
Jim
A couple of queries. He checked the duration of the cams that were bought by the previous owner (many many years ago) which I'd always assumed were the 260/260 kit. He found the actual duration to be more like 263/256. This is a guide as the measurement accuracy is +/- with the closest being 262/258 and the worst being 265/254. The intake was consistently a little higher than the exhaust though which reading up is not normal on turbo cars.
I understand if you do split timing on a turbo car it should be the exhaust side that's slightly higher rather than the intake. I can only think it's to help low/mid range that you might use for a rally car rather than the max HP you look for on a drag car? To be honest it's close enough to what I want on a car to not worry about though I'd appreciate people's views.
More concerning is the cam timing. For my last engine build (only "many years ago") I'd simply followed Piper's guidance for 110/110 (Inlet/Exhaust timing) given on their website:
http://www.pipercams.co.uk/pipercams/www/product_nav.php?type=C&cat=CM&man=16&engine=222
Double checking on the internet I understand the OEM cam timing is 110/120 for our SR20DET.
Tomei recommend a 110/115 setting for all their camshafts on our engine
HKS recommend a 108/114 for all their camshafts
My concern is Piper developed the cams for the Primera SR20, as this is the only other application referenced on their site, and lazily transferred the settings over for the GtiR?
I know that to tune the cams in I ideally need a rolling road but I want a decent starting point. On my last map I had to do some abnormal mapping for idle and cruise that I'd not seen on other cars. A 10deg shift on the exhaust cam is pretty significant if Piper have just done a copy and paste error!!!
What other timing suggestions are given by manufacturers for our cars. As with the Tomei and HKS recommendations, I'd expect most to be in a similar range?
Cheers,
Jim