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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
8th Jul, 2012 at 09:21:07pm
Hey guys here's the 998 Pockets Tech Drawing for download
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 4619 Posts Member #: 20 My sister is so fit I won't show anyone her picture Lake District |
8th Jul, 2012 at 09:26:01pm
Nice one ! Thanks for sharing. I presume the cutouts are to provide clearance for the 29mm ex valve ? Edited by Turbo Phil on 8th Jul, 2012. |
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
8th Jul, 2012 at 09:29:12pm
I think so Phil not 100% sure
Edited by Chalkie on 8th Jul, 2012. |
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1391 Posts Member #: 1686 Post Whore Oxford |
9th Jul, 2012 at 09:36:18pm
Half the size of the diamater.
On 8th Jul, 2012 RidingLow said:
I think so Phil not 100% sure well exhaust valve is 29mm and the Radius is 18mm so if I remember right Radius is twice size of Diameter? On 19th Feb, 2011 Miniwilliams said:
OMG Robert that's a big one |
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 36 Posts Member #: 9909 Member Tyler, Texas |
11th Jul, 2012 at 01:22:21pm
Awesome! i was just looking for something like this! Greatly Appreciated -1974 Mini 1000 - BRG Turbo Build Soon to come
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 1750 Posts Member #: 10190 Post Whore belgium |
8th Sep, 2013 at 04:23:41pm
Idemdito as luke... so the valve centre sits 2, 24 mm more to the back as the bore centre... how deep would you go? you can do anything if you set your mind to it...
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 319 Posts Member #: 1742 Senior Member essex |
8th Sep, 2013 at 06:13:25pm
Depth depends on if the blocks been skimmed, piston crown to ring grove, how far down the piston is from block surface, how much value lift you got (valve above head surface) then give a little clearance. My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901 |
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
8th Sep, 2013 at 08:14:51pm
5mm the drawing gives |
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1750 Posts Member #: 10190 Post Whore belgium |
8th Sep, 2013 at 08:22:52pm
its all metro standard stuf. head been skimmed once. i have 1 mm clearance now. how much should i have to be ideal? i ran it once with that 1 mm for a week but inlets came white so took it back of. Edited by Rammie2000 on 8th Sep, 2013. you can do anything if you set your mind to it...
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 1767 Posts Member #: 9165 Previously josh4444 Australia, brisbane |
9th Sep, 2013 at 08:33:28am
surely if the big valve is in a small bore than the extra flow the valve gives is sacrificed due to the block shrouding the valve
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
9th Sep, 2013 at 04:40:06pm
On 9th Sep, 2013 Turbo This.. said:
surely if the big valve is in a small bore than the extra flow the valve gives is sacrificed due to the block shrouding the valve i think that the standard head/block arrangement is poor due the the std head being larger than the bore to start with surely this over hang is a bad thing? They do say not to put a Big valve head on. On a standard valve setup it be okay a little bit is sacrificed due to the block blocking it but not too much You could blend the pocket into the bore its self, gain some flow around the piston area but not sure how this will fair up |
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319 Posts Member #: 1742 Senior Member essex |
9th Sep, 2013 at 06:05:36pm
but the 998 head chamber over hangs the block also its only because the chamber depth is different. My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901 |
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36 Posts Member #: 9909 Member Tyler, Texas |
9th Sep, 2013 at 06:08:06pm
Shrouding will kill the flow of the head and cause less power on that head, but not necessarily less power for that motor. I don't know all the flow numbers for these heads, but i would guess on a smaller displacement engines it could cause an over all power loss. However when its boosted, its all being shoved in anyway so the effect will not be as pronounced. I am pocketing my block to fit a SC 7 port head and not just a standard big bore head. I know there will be shrouding, but its the best compromise for me. -1974 Mini 1000 - BRG Turbo Build Soon to come
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319 Posts Member #: 1742 Senior Member essex |
9th Sep, 2013 at 06:20:03pm
there was an article in one of the keeping a mini alive magazine specials they wanted to see what was possible with a small bore engine. they started off building a plus .040" bore "special cam" engine with 10.5cr but running a 1.5" carb and ported small bore head. They had pocketed the block ready for next stage. it was dyno'd and run in. then they swapped carb for hiff 44 re dyno then swapped head for a ported 12g940 keeping same compression ratio and then re dyno'd the head and carb conbo made large difference and I believe they peaked at about 90bhp. I will try to dig it out and confirm the figures My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901 |
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1750 Posts Member #: 10190 Post Whore belgium |
9th Sep, 2013 at 07:19:03pm
if i mesure the valve on the big bore and on the small bore i do see that although it over hangs the free part is still bigger than a standard 998 head. you can do anything if you set your mind to it...
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
11th Sep, 2013 at 12:23:31pm
I've seen this done before (Excuse the shit picture I used Paint)
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1750 Posts Member #: 10190 Post Whore belgium |
11th Sep, 2013 at 06:44:40pm
Wouldn't you expose evan more ring to hot gasseson this way? you can do anything if you set your mind to it...
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
11th Sep, 2013 at 10:03:58pm
I didn't come up with the idea :] why I asked
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1750 Posts Member #: 10190 Post Whore belgium |
28th Sep, 2013 at 05:49:42pm
Question. Getting the block pocketed tomorrow but for the build... do i use 1275 puchrods or the original ones? you can do anything if you set your mind to it...
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
28th Sep, 2013 at 06:15:44pm
No you use the 998 push rods
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1750 Posts Member #: 10190 Post Whore belgium |
28th Sep, 2013 at 07:23:57pm
Right its the block thats higher. . Deuuh. Forget that i asked. Big head ,twin 1, 25s... can't wait. you can do anything if you set your mind to it...
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1909 Posts Member #: 9764 Post Whore Northamptonshire. |
28th Sep, 2013 at 11:41:43pm
Nice!! Im tempted on a benross 12g295 or a 940 lightly done
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1750 Posts Member #: 10190 Post Whore belgium |
1st Oct, 2013 at 08:20:23pm
does it have to be drilled 5 mm? how much mm is there from deck of the piston to the ring? i have flat tops ( come fluch with the block deck made 11 cr with modded 998 head) in the block right now. going to drill them in but without removing pistons. ( they will be closed of by a rubber insert and grease so the debree cant fall in to the ring land)
Edited by Rammie2000 on 1st Oct, 2013. you can do anything if you set your mind to it...
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 361 Posts Member #: 114 Senior Member Porto/Portugal |
29th Aug, 2015 at 08:44:14pm
Can anyone tell if there is a minimum distance between the pocket and the top of the first ring? if so, what is the minimum distance? Pedro Silva
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1750 Posts Member #: 10190 Post Whore belgium |
30th Aug, 2015 at 08:06:58pm
i left about 3 or 4 mm as i remember. its been about 1.5 or 2 years now ridding it hard and still goes you can do anything if you set your mind to it...
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