jumpbike Posted December 6, 2014 Share Posted December 6, 2014 So before my rebuilt 2nd turbo failed after 20 miles the engine was never quite running right, was slightly missing at idle but was smooth when driving and revving. About to put the turbos back on again and thought hmmmm I'll check the plugs because I suspected the rear cylinder was at fault after unplugging the coils to find the faulty cylinder. Removed the plug and half the ground electrode is missing along with some of the insulation material. All others seemed fine. Boroscoped the bore and the piston doesn't look too fresh, very pitted and lumpy round the edge. Couple the others have the odd bit in 1 place but number 6 is the worst. As I said it was running very smooth and I'm half thinking with a new plug might it be okay? Worse case, the scoring doesn't seem deep, just faint lines up the bore, is this likely to hone out and also are NA pistons a match because I have a GE engine to break if needs be and add some fresh rings. Cheers Quote Link to comment Share on other sites More sharing options...
JamieP Posted December 6, 2014 Share Posted December 6, 2014 Might be ok, no harm trying. NA Pistons are different. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 6, 2014 Share Posted December 6, 2014 I would suspect the damage is already done if your seeing det damage on the piston tops, its quite likely that the ring lands are damaged, personally I would play safe and rebuild/hone. Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 7, 2014 Author Share Posted December 7, 2014 problem is, engines not in a supra so it's engine out to get the turbos off, so its currently out, still a massive faff to rip it apart to get at the bores, maybe I can leave it half built with crank in etc. to swap pistons and clean up, leave head as complete as possible and list in 1 go. Not a fan of going into winter with my only mobile car being my track car so that's why I was hoping it might survive even for 6 months. Can anyone confirm the NA pistons are different? Quote Link to comment Share on other sites More sharing options...
np89 Posted December 7, 2014 Share Posted December 7, 2014 Obviously they will be different as the NA will run a much higher CR Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 7, 2014 Author Share Posted December 7, 2014 Not so obvious because people have sat them side by side with a pin between the holes and the tops look identical, if I get a used set of TT ones I'll strip the GE and do it for reference Quote Link to comment Share on other sites More sharing options...
np89 Posted December 7, 2014 Share Posted December 7, 2014 Lol......ok.......dead on Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 okay, it's in bits, I don't think I've had detonation but rather some foreign objects in the rear 3 cylinders, I've got matching damage on the edge of the pistons and the head. Because the edge of the pistons have been broken off this has scored the cylinder walls. Also the head gasket had blown between the rear 2 cylinders which I wasn't expecting so there is also a slight groove in the head where it has been blowing past that I need to polish out. Question I have now is i'm going to change the pistons and hone the bores best I can but as I do not have the time/money to go for a re-bore at the moment, will new piston rings seat okay in scored bores. There's the odd long score in each bore but in one of them there's a lot all bunched up together about an inch long. Obviously not perfect and I don't expect it to be but I need it working ASAP, a fresh head gasket it going to make a massive difference to a blown one. It was running fine before just missing slightly at idle (obviously the head gasket) So far, some tidy used pistons, new rings, new big ends and hardware to bolt it all back together. fingers crossed it gets me into the summer Quote Link to comment Share on other sites More sharing options...
Mk4Gaz Posted December 23, 2014 Share Posted December 23, 2014 Not a chance mate, you cannot rebuild the engine with damaged cylinder walls! The bores need measuring to see if they're still round, and a rehone will be the very minimum needed. However, with scored cylinder walls, it'll need a rebore and oversized pistons - or new liners fitted. There is no cheap way out of it I'm afraid, I'd get the block to a specialist, along with the short block components, and have it rebuilt and balanced properly. Please don't rush into it or cheap out, you'll regret it later. Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 okay, it's in bits, I don't think I've had detonation but rather some foreign objects in the rear 3 cylinders, I've got matching damage on the edge of the pistons and the head. Because the edge of the pistons have been broken off this has scored the cylinder walls. Also the head gasket had blown between the rear 2 cylinders which I wasn't expecting so there is also a slight groove in the head where it has been blowing past that I need to polish out. Question I have now is i'm going to change the pistons and hone the bores best I can but as I do not have the time/money to go for a re-bore at the moment, will new piston rings seat okay in scored bores. There's the odd long score in each bore but in one of them there's a lot all bunched up together about an inch long. Obviously not perfect and I don't expect it to be but I need it working ASAP, a fresh head gasket it going to make a massive difference to a blown one. It was running fine before just missing slightly at idle (obviously the head gasket) So far, some tidy used pistons, new rings, new big ends and hardware to bolt it all back together. fingers crossed it gets me into the summer When will people realise you can't build an engine on a buget and skimp out. And yes you have had detonation, piston edges breaking off and pitting is a classic sign of detonation. If you dont have the money right now save up and do it once and do it right. DO NOT REBUILD WITH USED PISTONS that have signs of damage on them as I suspect you are going to try and do and even if they are a new set you will still need the bores rehoned and sized for THAT SPECIFIC piston. I suggest you consult an expert or just give them the lot and tell them to make it right because, no harm to you, it doesn't sound like you have a clue about building engines. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted December 23, 2014 Share Posted December 23, 2014 If the scoring cannot be removed with a light hone...which I doubt, then its totally pointless going forward without a re bore and new pistons and rings, Leaving the scoring will just loose cylinder pressure and create hot spots, The very fact that you say you have two turbos fail in a very short period would indicate that you have serious problems, and this should be investigated comprehensively before proceeding any further, or you will just be wasting your money and time. Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 A rebore means new ecu etc. To map it corretly. And as its auto and basically bpu I can't justify an ECU that will control the auto as well. I can't be driving round in a track ready 200sx any more so looks like engines going on the scrap pile and I'll just buy something else. Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 Have you actually lost your mind? Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 Like i said, give it to someone who knows what they're on about and never worry Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 I got the complete engine with auto box turbos ECU the lot for under a grand, the scrap pile is the most financially viable option for it after wasting a year on the trash Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 Ill buy it for the scrap value then if you like Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 23, 2014 Share Posted December 23, 2014 A rebore means new ecu etc. To map it corretly. And as its auto and basically bpu I can't justify an ECU that will control the auto as well. I can't be driving round in a track ready 200sx any more so looks like engines going on the scrap pile and I'll just buy something else. There's no reason whatever for a rebore to the next oversize that will clean the bores up requires a new, different, or mappable ecu. However, i do get the impression that you are not willing to spend the required budget on doing it right. These are expensive engines to rebuild, and a lot of work. Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 Well there you have it jumpbike, from one of the best tech minds on the forum Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 But if I over bore it the displacement will be 2.3% bigger so will it not need 2.3% more fuel to account for the extra air that's being dragged in to. As it has no maf sensor it can't just adjust based on airflow. I'm gonna push it all to 1 side and fix a different car so I can think. A big reliable 1HD-FT engine instead for now Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 23, 2014 Share Posted December 23, 2014 (edited) For a start you have the maths wrong I think. Not that it's at all a strong subject of mine Stock bore and stroke = 86 x 86 mm Overbore to first oversize, which is 86.5mm Capacity of engine increases from 2.997 litres to 3.032 litres. That's a percentage capacity increase of 3.5% No matter, the stock ecu will not be concerned, the MAP sensor will see the tiny additional depression at X RPM and with the bigger capacity, and compensate. What's a 1HD-FT when it's at home please? And air is not "dragged" into an engine, atmospheric pressure pushes it in, or in a supercharged engine, the supercharging device(s). Edited December 23, 2014 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 ....owned lol Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 ^^^^ nob... who hasn't made 1 positive contribution and if all your going to do is throw shit maybe you should go back to the monkey cage and carry on with what you're good at. @Chris - Maths is one of my strong points and based on a 1mm over bore which gives 3067 cc, this in an increase of 2.33...%. I understand what you're saying now that the manifold pressure will vary slightly with the new capacity simply causing the MAP sensor reading to change and alter the fuelling to compensate. A 1HD-FT is a 4.2 24 valve turbo diesel engine from the larger Toyota Land Cruiser. Mechanical fuel pump, no electronics, just runs and runs. The none turbo variant the 1HZ is used in most military Land Cruisers all over the world in the desert and is probably 1 of, if not the most reliable engines ever made. I'm coming around a bit now to a rebore, 1mm over size utilising my trip to America in Jan to get a set of pistons and then fresh shells for every thing else. Yet to inspect the valves and seats for damage but there's no obvious damage visible around the closed valves. thanks for your input Quote Link to comment Share on other sites More sharing options...
np89 Posted December 23, 2014 Share Posted December 23, 2014 ^^^^ nob... who hasn't made 1 positive contribution and if all your going to do is throw $#@! maybe you should go back to the monkey cage and carry on with what you're good at. @Chris - Maths is one of my strong points and based on a 1mm over bore which gives 3067 cc, this in an increase of 2.33...%. I understand what you're saying now that the manifold pressure will vary slightly with the new capacity simply causing the MAP sensor reading to change and alter the fuelling to compensate. A 1HD-FT is a 4.2 24 valve turbo diesel engine from the larger Toyota Land Cruiser. Mechanical fuel pump, no electronics, just runs and runs. The none turbo variant the 1HZ is used in most military Land Cruisers all over the world in the desert and is probably 1 of, if not the most reliable engines ever made. I'm coming around a bit now to a rebore, 1mm over size utilising my trip to America in Jan to get a set of pistons and then fresh shells for every thing else. Yet to inspect the valves and seats for damage but there's no obvious damage visible around the closed valves. thanks for your input Lol....ok, I think you'd find your response there a bit more in keeping with that spectrum if you knew what I actually did day to day but anyway. Good luck, sounds like you have it sussed ! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted December 23, 2014 Share Posted December 23, 2014 jumpbike, yes, apologies, your maths is spot on, I was basing the percentage increase in capacity on an over bore of .5mm (you can get 86.5mm pistons from some companies, as well as 87mm). So that should have been about 1.16% increase in total capacity. How I got 3.5% I don't know, probably time for bed The all mechanical Toyota diesel sounds my sort of thing, modern direct rail diesels are a nightmare and hugely expensive if they go wrong! Anyway, happy Christmas and a healthy and prosperous New Year to you. If you are going to the US you should be able to pick up some Wiseco, JE or similar pistons very reasonably. Be wary of any that run Spirolox fasteners for the pins, and not proper round section wire circlipos, I have had some terribly expensive issues with Spirolox coming out. Good luck with it. Quote Link to comment Share on other sites More sharing options...
jumpbike Posted December 23, 2014 Author Share Posted December 23, 2014 okay, thanks for the heads up, I was looking at the Wiseco as they seem recommended and also relatively cheap compared to some. funny thing about my engine when I took it apart, I removed the rear piston first, slid it out and sat resting half in the pin hole and half just on the side of the piston was a pin fastener thing. I looked at both sides of the piston, hmmmmm okay both still in. Haven't looked closely at the others but i'm sure id know if 1 came out. What the hell! How did it get there, how long has it been there?? How was it not just sat in the sump... Quote Link to comment Share on other sites More sharing options...
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