beeto Posted October 31, 2017 Share Posted October 31, 2017 I have had my Cam profiled with it returning the below. It will be used in mostly a street car, with 3x40dcoe - looking for Drive-ability with some power Can someone help me decipher this? A comparable cam to the MSA Schinider S1, S2, S3 or something, power range, engine characteristics? Thanks HP_SCAN_0009 (1).pdf Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted November 1, 2017 Share Posted November 1, 2017 (edited) Doing a little math it looks very similar to my Colt C542s cam, or previously called the Shadbolt M445. .490 lift, 290 degrees duration. Without me actually looking at the Schneider cam specs, I'd be guessing around their Stage 3, or even their stage 4. Getting pretty aggressive, but still very street able. Lumpy idle. Edited November 1, 2017 by HuD 91gt Quote Link to comment Share on other sites More sharing options...
turbogrill Posted November 1, 2017 Share Posted November 1, 2017 The centerline and LSA numbers doesn't make sense to me, using my homemade spreadsheet I get: LSA: 110 Intake centerline: 119 Exhasut centerline: 102 Anyone else want to have a go? One explanation would be if the lobes are asymmetrical (as in one side steeper than the other). It also has a higher duration on intake than on exhaust? Makes me think is a Turbo cam shaft, NA usually has it other way around. Also most 290 duration NA cams seem to have over 70 degree overlap, again maybe it's a turbo grind. But 65 degree overlap seems a lite much for turbo cam... So not sure Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted November 1, 2017 Share Posted November 1, 2017 (edited) Lobe separation angle is quite narrow so I doubt it was designed as a turbo cam. It states at the top 107.6. Any idea how your math gets 110? Edited November 1, 2017 by HuD 91gt Quote Link to comment Share on other sites More sharing options...
Chickenman Posted November 1, 2017 Share Posted November 1, 2017 10 hours ago, turbogrill said: The centerline and LSA numbers doesn't make sense to me, using my homemade spreadsheet I get: LSA: 110 Intake centerline: 119 Exhasut centerline: 102 Anyone else want to have a go? One explanation would be if the lobes are asymmetrical (as in one side steeper than the other). It also has a higher duration on intake than on exhaust? Makes me think is a Turbo cam shaft, NA usually has it other way around. Also most 290 duration NA cams seem to have over 70 degree overlap, again maybe it's a turbo grind. But 65 degree overlap seems a lite much for turbo cam... So not sure Shadbolt grinds, and therefore Colt grinds were asymmetrical. . In fact most of the " good " performance L-series grinds are . It has to do with the weird changing rocker arm ratio as the Cam slides across the rocker pad. Quote Link to comment Share on other sites More sharing options...
Chickenman Posted November 1, 2017 Share Posted November 1, 2017 Go by the Cam sheet. In this case the LSA is 107.6 which makes sense. The Intake and Exhausts LCA's are set 4 degrees advanced. Definitely not a Turbo Cam. Too much overlap. and too Narrow of an LSA as Colten mentioned. Quote Link to comment Share on other sites More sharing options...
turbogrill Posted November 1, 2017 Share Posted November 1, 2017 55 minutes ago, Chickenman said: Go by the Cam sheet. In this case the LSA is 107.6 which makes sense. The Intake and Exhausts LCA's are set 4 degrees advanced. Definitely not a Turbo Cam. Too much overlap. and too Narrow of an LSA as Colten mentioned. Ok. Using either centerline or LSA from camsheet gives me correct LSA/Centerlines. Curious about the reasoning with longer intake duration? Maybe this has something to do with the asymetrical lobes causes "slower"opening in the opening. This is just pure gibberish speculations btw... 1 hour ago, HuD 91gt said: Any idea how your math gets 110? My spreadsheet seem to work well for Schneider cams Maybe they don't have asymmetrical lobes... All valve events are relative ATDC (I find ABDC, BBDC just confusing) Overlap = ExhaustClose - IntakeOpen DurationI = IntakeClose - IntakeOpen DurationE = 720 - ExhaustOpen + ExhaustClose IntakeCenterLine = DurationI/2 - IntakeOpen ExahustCenterLine = DurationE/2 - ExhaustOpen LSA = ( IntakeCenterLine + ExhaustCenterLine) / 2 Quote Link to comment Share on other sites More sharing options...
Chickenman Posted November 1, 2017 Share Posted November 1, 2017 Could be that the Shneider grinds are symmetrical. Often cam grinders use a " Profile " from a different engine and juts grind it down till the lift number matches what they want. Saves them monet on developing Master Cam Lobes. It's not the correct way though for Datsun cams. Talked to Barry at Shadbolt many, many years ago ( Late 70's ) and he explained why the L-series needed an asymmetrical profile. I think he said even the stock camshafts were asymmetrical.... but don't hold me to that. It was a long time ago. All the L-series Race cams that I have seen from the original Nissan Comp catalogs and Electromotive were asymmetrical. As were the Racer Brown and Malvern Racing cams ( I believe ) Quote Link to comment Share on other sites More sharing options...
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