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| Home > Help Needed / General Tech Chat > Headgasket failure and deposits on valves and plugs | |||||||
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113 Posts Member #: 11786 Advanced Member |
9th Oct, 2020 at 04:35:19pm
I keep you guys updated - but wont be able to get it oit soon - this is going to be my winter project |
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 2618 Posts Member #: 1246 Post Whore Lowestoft, Suffolk. |
9th Oct, 2020 at 06:34:04pm
Does the Wideband that you are using have a 0 to 5v output that you can connect to the SC engine management and use to adjust the fueling?
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113 Posts Member #: 11786 Advanced Member |
10th Oct, 2020 at 06:29:49am
hey, yeah i am feeding the afr gauge in the ECU but didnt use the closed loop. i was plannimg to use the closed loop in the off boost areas below 4000rpm once i habe a good setup otherwise |
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 (2)[/url] by [url=https://www.flickr.com/photos/150672766@N03/]Rod Sugden[/url], on Fli) 5988 Posts Member #: 2024 Formally Retired Rural Suffolk |
10th Oct, 2020 at 07:33:34am
On 8th Oct, 2020 Joe C said:
a few scratches... id say the bores are toast, if those marks were from the last build then oils getting up past the rings, if they are fresh then, either the rings have not got enough end gap, or theybe been mega hot, or det has taken the ring lands out. Agree with Joe, but I'll just add one to the list - insufficient piston to bore clearance. What make of piston (cast or forged), what was the bore clearance set to, and what were the ring gaps ? Also I'm not clear if it is already +60 or you are intending to go to +60 because I doubt you will get away with just a hone to remove those "scratches". Can't be certain until the pistons are out and you see the full length of the bore plus the camera has picked up some funny reflection of the top of the piston, but I doubt it. Schrödinger's cat - so which one am I ??? |
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2618 Posts Member #: 1246 Post Whore Lowestoft, Suffolk. |
10th Oct, 2020 at 08:44:54pm
On 10th Oct, 2020 JackZwiebel said:
hey, yeah i am feeding the afr gauge in the ECU but didnt use the closed loop. i was plannimg to use the closed loop in the off boost areas below 4000rpm once i habe a good setup otherwise Shane |
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113 Posts Member #: 11786 Advanced Member |
12th Oct, 2020 at 07:28:42am
since i didnt build the engine in the first plave i dont know what make the pistons are - but the are forged pistons. I dont know what the clearnce is but my engine builder told me he uses a bigger clearance on turboed engines.
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5988 Posts Member #: 2024 Formally Retired Rural Suffolk |
12th Oct, 2020 at 10:24:55am
On 12th Oct, 2020 JackZwiebel said:
....... but the are forged pistons. I dont know what the clearnce is but my engine builder told me he uses a bigger clearance on turboed engines. The bigger for turbo is good but some builders would even add a little bit more for forged pistons. Personally I would so it will be interesting to see (when you get to it in winter) if they have had a clearance issue. On 12th Oct, 2020 JackZwiebel said:
From measuring the bores (71,5mm) i assume it is at +40 right now. So i would go to +60. Is a offset bore necessary at +60?. Theoretically no as it's a quoted factory size. It's very necessary if you were using the non-standard very large oversizes, like 73mm pistons (which is +094) or larger still because the wall thickness between 2 and 3 would not hold a gasket (and would flex under cylinder pressures stopping the rings sealing properly). At +60 you have still reduced that wall thickness where the gasket sits by 60 thou (30 thou removed from either side). Some people might say do it at +60 just to help the gasket, but you're too late anyway - well, too late to do it in any meaningful way. With a used bore, and particularly one with "scratches" in them, they would still have to take a certain amount out of that middle wall just make sure it cleaned up and the cutting tool left a circular bore. So the offset achievable starting with a damaged +40 would be negligible. I had mine done on a +nothing, just slightly worn, block (I'm 73mm, ie 1360cc). Schrödinger's cat - so which one am I ??? |
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113 Posts Member #: 11786 Advanced Member |
13th Oct, 2020 at 06:11:11am
Thanks for all that info.
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4300 Posts Member #: 1321 Post Whore Wiltshire |
13th Oct, 2020 at 07:15:15am
7 port set up should be suitably fun. Cast pistons should be more than adequate for that set up.
On 7th Oct, 2010 5haneJ said:
yeah I gave it all a good prodding |
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242 Posts Member #: 11017 Senior Member Shropshire |
13th Oct, 2020 at 08:25:03am
On 13th Oct, 2020 JackZwiebel said:
Thanks for all that info. I am currenty calculating the costs if i go the n/a route - mostyl because there are more people around who have experience with n/a than with turbo minis. And since i always wanted a n/a 7 port engine this would be a good occasion to go that way 
I am in contact with SC aleady about the stuff i need. Would you guys use forged pistons in n/a applications as well? Aiming for a CR of 11.25:1. Also i want to get rid of my straight cut setup since its simply too loud for longer trips. I am thinking of replacing just the drops, but i am not sure how much it gets the noise down? Are helical drops with SC gearbox bearable or should i go right to the helical evolution gearbox from minispares? Go MS Evo Helical. Loads of high powered engines beginning to use these now and showing good results. |
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113 Posts Member #: 11786 Advanced Member |
13th Oct, 2020 at 01:00:20pm
Really depends if they are still in the budget. Guess going for helical drops will cut a lot of noise already.
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