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| 296 scatter cam, anyone tried? https://www.ausmini.com/forums/viewtopic.php?f=2&t=73959 |
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| Author: | Babes [ Sat Nov 05, 2011 1:03 pm ] |
| Post subject: | 296 scatter cam, anyone tried? |
I have just come into possession of an A+ short motor which looks to have had a huge amount of money thrown at it. It has a 296 scatter cam in it and I'm wondering if this will be good for my supercharged A+1293 which currently runs a stock metro turbo cam. I have read numerous conflicting stories so was wondering if anyone has had first hand experience with this cam? The car Im thinking of putting it into is only a weekend toy but the build im going for is reliability over anything else. |
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| Author: | dodge [ Sat Nov 05, 2011 1:52 pm ] |
| Post subject: | |
Because of the negative effects of overlap on a supercharger car’s performance, and especially in the case of high exhaust back pressure as is the case with most factory supercharged cars, we find that the optimal cam duration for the intake cam is typically 30-40* of duration less than a normally aspirated camshaft for the same peak power RPM. The decision to reduce the intake cam duration rather than split the duration reduction between the intake and exhaust cams, is that the intake cam will flow air under pressurized conditions (due to the addition of the supercharger and the increase in intake manifold pressure) and so at a reduced intake cam duration the engine will still be able to get it’s full share of intake air. At the same time, the high rpm effeciency improvement from the reduction of overlap will also boost power production with a more conservative cam. Finally, if we would like to get more flow from the intake cam, there is still the option of using a higher lift camshaft (with a steeper profile due to the decreased duration) with supporting valvetrain modifications to make sure valve float doesn’t occur at higher rpms. |
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| Author: | drmini in aust [ Sat Nov 05, 2011 2:23 pm ] |
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^^ short version= there is so much valve overlap with big cams you will blow 1/2 the intake charge down the exhaust port whilst both valves are open. 
The usual fix for this is reduce the duration by heaps, or increase the LCA (which Graham Russell does for his turbo grinds). I would forgo using the 296, and get an RE13T, which is designed for boost and kicks a Metro turbo cam's arse out the window. 
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| Author: | Babes [ Sat Nov 05, 2011 2:51 pm ] |
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Ok, might just leave the SC engine it as is for the time being then. The moke has a metro engine, twin carbs, electronic dissy, extractors etc. Would this be better suited for it? |
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| Author: | KPV [ Sat Nov 05, 2011 8:12 pm ] |
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Dont be looking at your moke  You have a traveller that needs some lovin first 
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| Author: | Babes [ Sat Nov 05, 2011 9:03 pm ] |
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Yes must focus on the traveller but that short motor keeps looking at me. Your fault you should of taken it Mr hot 1100 build. |
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| Author: | KPV [ Sun Nov 06, 2011 9:37 am ] |
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A question for those in the know.Would more boost overcome the overlap problem?I know it wont eliminate the loss but if your losing half can you just put twice as much in? |
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| Author: | drmini in aust [ Sun Nov 06, 2011 2:00 pm ] |
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Um... No it won't.
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| Author: | KPV [ Mon Nov 07, 2011 9:03 pm ] |
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Thanks Doc
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| Author: | Babes [ Tue Nov 15, 2011 6:53 pm ] |
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Here are some pics of the short motor, what are the shiny rings around the bore? 
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| Author: | mini_mad_matt [ Tue Nov 15, 2011 7:05 pm ] |
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The "rings" around the bore are sleeves. So the block has been bored out then had sleeves put it. |
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| Author: | Babes [ Tue Nov 15, 2011 7:18 pm ] |
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Is that a good or a bad thing? |
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| Author: | norton [ Tue Nov 15, 2011 7:29 pm ] |
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mini_mad_matt wrote: The "rings" around the bore are sleeves. So the block has been bored out then had sleeves put it.
I'm thinking they flame rings coz its built for big compression |
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| Author: | lisian_1275 [ Tue Nov 15, 2011 7:33 pm ] |
| Post subject: | Rings in Block |
Hi No Sorry not sleeves.The rings in the top of the block around the bores is called 'O' Ringing. This is done to put more bite into the head gasket to seal better.Used to be standard performance thing to do for years. Thanks Ian |
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| Author: | mini_mad_matt [ Tue Nov 15, 2011 7:33 pm ] |
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hmm i just had a closer look at the picture and i think you're right norton. My bad. |
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