Leon Posted August 7, 2012 Share Posted August 7, 2012 Isn't the main issue that without an ECU it's not possible to optimize spark across the rev range, adjust mixtures at a variety of engine conditions, etc? Nothing wrong with going old skool, but to Mack's point, seems strange to spend so much on a premium bottom end and not take advantage of optimizing fuel and spark to get the most out of the motor. Right, those would be the main issues. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 8, 2012 Share Posted August 8, 2012 As Leon mentioned, the Tau Layer is fuel coating the walls of the runners. The KEY to proper mixture control is to keep the Tau Layer CONSISTENT. The problem that confounds ALL high-end EFI tuners is the transitionals to keep the Tau constant. For carbs....well... "Just go rich, and you will be safe"... I got 17MPG on my 350HP Blow-Through Mikuni L28 for YEARS. (Decades, actually...) Better than the SU's that were on it formerly, tell the truth. With EFI, my drivability problems went away, my transitional driving smoothed out immeasurably, and my mileage went up to high 20's. Cruise on the freeway went from 17 to 29-31mpg. On track mileage was identical: 4-5mpg if I'm lucky. And with all that being said...I revert to the original statement, REGARDLESS of your setup: You can have the best components in the world. It doesn't mean that ONE thing failing ONCE won't turn it all into a pile of scrap instantly. And you may never HEAR anything. The detonation you hear is 'safe'---you pull your foot. What about the thousands of miles you drove without ever hearing it? Quote Link to comment Share on other sites More sharing options...
280zex Posted August 8, 2012 Author Share Posted August 8, 2012 ok so the guy from the Portland shop stoped by and took a look. He agreed that the parts installed WERE NOT the parts I originaly provided for the lower end rebuild. However the issue is that I cant prove the lower end I currently have was the one his shop suposedly built for me. It has been 5 years. He did agree to re-hone the cylinders, press new pistons for me, and replace all the gaskets. Looks like I'm out just a set of pistons and some R&R time. This time I asked that the shop make a mark on the block, to properly identify it, just incase things go wrong again. In his opinion the damage was due to improper lubrication at high rpm's, or just way too many high rpm's in the first place. Gota keep it under 6500 if I want my engine to stay together. Yes I run a O2 sensor, with datalog. never had a lean out. The setup never showed signs of an issue until I noticed alot of smoke out the back when getting off the freeway. I had spunt it to 8k, so thats probibly where the issue came from. Atleast the shop in Portland is going to make things right, thats all I asked anyway. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 8, 2012 Share Posted August 8, 2012 Lucky for you. A shop that covers for 5 year old mistakes is a pretty good shop. Are you saying that you provided Wiseco forged pistons and the Seattle shop swapped them on you? Or they sold you Wiseco but put something else in? Or they are Wiseco but blew up due to high revs and/or poor lubrication? Doesn't improper lubrication and/or too high RPM imply scuffing/seizing and heat buildup? Where do the broken ring lands come in? Still curious. Quote Link to comment Share on other sites More sharing options...
280zex Posted August 8, 2012 Author Share Posted August 8, 2012 I provided the parts to the shop. They were not the parts I found in my engine during teardown. cyl's 23456 show signs of scuffing, not bad, you can see it with the eye but they mic ok. The guy from the Portland shop and I have been friends for 15 years, so I'm suprized that he didnt just fix my issue. However he does have a point that the engine lasted for 5 years and I cant realy prove anything other than I have receipts, but no real way to prove that the block in question was the block they machined for me. So its a stale mate on that issue. His best guess is that the excessive high rpm's and incorrect setup had caused the 2nd ringland on piston 3 to brake. Its a small piece, mabe 1.5 inch in length right under the 2nd compression ring that broke. I didnt even notice until I was checking to see if a ring had stuck or something, then a small piece came off in my hand. I had the Z on a dyno with plenty of equiptment checking fuel and spark curve, and the knock sensor hooked up. Nothing ever showed as a problem from the day I assembled the engine. My shop friend doesnt believe that detonation was the cause, but who realy knows right??? I never had a hickup, pop or backfire of any sort. I am changing out the air/water innercooler for water/meth spray, just to add piece of mind. The people who showed me how to turbo blown thru a holley had a mustang on the dyno with NO INNERCOOLER, NO METH SPRAY, 92 octane, NO SPARK ADVANCE/RETARD, pushing 25lbs of boost, on pump gas and ran 850rwhp. I am fairly shure my issue was too many rpm's/ improper parts / oil lubrication... Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 9, 2012 Share Posted August 9, 2012 (edited) Sounds like the owner is being reasonable given the long time that has passed and the visual indications of poor lubrication. Sounds like you need to verify oil pressure once you get the engine running again. You may need to shim the oil pressure relief spring in order to get enough pressure at high revs. Hopefully you're using something more accurate than the stock gauge ... Edited August 9, 2012 by Zmanco Quote Link to comment Share on other sites More sharing options...
280zex Posted August 9, 2012 Author Share Posted August 9, 2012 Sounds like the owner is being reasonable given the long time that has passed and the visual indications of poor lubrication. Sounds like you need to verify oil pressure once you get the engine running again. You may need to shim the oil pressure relief spring in order to get enough pressure at high revs. Hopefully you're using something more accurate than the stock gauge ... well the oil pump was new,turbo type, and the guade is an autometer mechanical type. idle is 10psi, freeway @3500 rpm's was about 60psi, or so says the guage. I'm wondering if there is a blockage somewhere?? I dont realy know, but this time the block is getting 2x the checks, thats for shure.. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 9, 2012 Share Posted August 9, 2012 5 years ago you had an L6 short block built, supposedly with parts that you had brought in. You've been revving it to 8,000 RPM with a blow-through turbo since then. It broke a ring land and the owner of the shop is going to help you out with free work and gaskets. I would like to know the name of that shop. This has turned from a shop-bashing thread to a shop-praising thread. Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 9, 2012 Share Posted August 9, 2012 Poor lube doesn't generally break piston ring lands; unless you have junk bonded to the bore. 8000RPM on cast pistons in an L28 is just bad juju all the way around. Might check the wrist pin holes for wear and stretching, bet you find some marks there. Those kinds of speeds are pushing the tensile strength of 90% of the cast piston material out there pretty hard, even if they have the steel braces inside. Quote Link to comment Share on other sites More sharing options...
280zex Posted August 9, 2012 Author Share Posted August 9, 2012 I got my new pistons and radiator in the mail. Now I'm off to find a shop to press the wrist pins for me as I dont have a press. The only thing that realy bothers me is that there is small pieces broken off the worm gear that drives the oil pump shaft. I didnt find them yet..... I am also picking up a MSD 6530 ignition box with adjustable rev limiter and fully programable spark curve. Quote Link to comment Share on other sites More sharing options...
Mack Posted August 9, 2012 Share Posted August 9, 2012 From how you describe the ring land breaking, it sounds like too many RPMs on a cast piston, so I and several others were wrong about the detonation, but still.... I know my cries are falling on deaf ears here, but for the price of that MSD box new at least, you could get a full EFI set up and be done with it. megasquirt for 180, an EFI manifold for 50, a fuel pump for 100 and various sensors and crap from the junkyard for probably another 100. then you could run COP and tune your spark AND fuel curves how you see fit. You could probably pick up a few HP and a lot of mpg. I am "just saying" Quote Link to comment Share on other sites More sharing options...
280zex Posted August 9, 2012 Author Share Posted August 9, 2012 From how you describe the ring land breaking, it sounds like too many RPMs on a cast piston, so I and several others were wrong about the detonation, but still.... I know my cries are falling on deaf ears here, but for the price of that MSD box new at least, you could get a full EFI set up and be done with it. megasquirt for 180, an EFI manifold for 50, a fuel pump for 100 and various sensors and crap from the junkyard for probably another 100. then you could run COP and tune your spark AND fuel curves how you see fit. You could probably pick up a few HP and a lot of mpg. I am "just saying" Ya I know, I actualy was running MS FI before the turbo/carb setup. I was after something different and I have that now. I'm shure there are others with the same type of setup, however I have only seen one other. Swecrazy I think has one, or atleast he has posted pix around here somewhere of a similar setup like mine. I just like the simple look of what I got and I'm sticking to it!! Quote Link to comment Share on other sites More sharing options...
seattlejester Posted August 10, 2012 Share Posted August 10, 2012 ^I applaud your steadfastness, I'll have to ask you some questions when I get around to doing a similar setup. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 12, 2012 Share Posted August 12, 2012 If you get a piston hot enough to close up the ring end gap solid, you can break ring lands. Our 2000+hp engine runs some pretty big ring end gaps. Quote Link to comment Share on other sites More sharing options...
280zex Posted August 21, 2012 Author Share Posted August 21, 2012 ok so here is the rest of the story. My friend at the portland shop found out what happened. The rods were installed backwards!! This explains the bad lubrication issue. So I got a new bottom end rebuild for free, new pistons, new rods, everything!! Other than a bottom rebuild, I'm only out the time its going to take for re-assembley, no money out of my pocket!! I should be running by this weekend Quote Link to comment Share on other sites More sharing options...
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