grillhands Posted April 19, 2015 Share Posted April 19, 2015 I have a n42 block and a p79 head. I'm running stock 280zx turbo with front mount and all N/A electronics. I'm using a fmu to crudely control fuel. Air/fuel is at 11.8 at 7psi and timing is set at 10 tdc with mechanical advance its total 27-29. The pcv functions normally and the vent cover is venting to a brand new rubber boot. Car pulls pretty well besides this problem. It only happens when I really get on it. Any suggestions would be great. Thanks. Quote Link to comment Share on other sites More sharing options...
TimZ Posted April 19, 2015 Share Posted April 19, 2015 Do a compression check. I don't think you are going to like the answer... Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 19, 2015 Author Share Posted April 19, 2015 Oh man. I'll do it over the weekend. This happened to my built audi. I was constantly blowing out the dip stick. What I did to fix it was I ran a line right after the filter so the suction of the turbo pulled out the vapors. I daily drove it for 2yrs at 28psi on a t3t4 50trim with a .63 ar. Ran like a beast Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 I had mine like this Quote Link to comment Share on other sites More sharing options...
Enginerd81 Posted April 20, 2015 Share Posted April 20, 2015 Make sure any crank case ventilation is functional as well. Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 This pic is exactly what I did on the audi. I'll probably do this tobth 280z as well Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2015 Share Posted April 20, 2015 I have a n42 block and a p79 head. I'm running stock 280zx turbo with front mount and all N/A electronics. I'm using a fmu to crudely control fuel. Air/fuel is at 11.8 at 7psi and timing is set at 10 tdc with mechanical advance its total 27-29. Remember hearing "you can blow up your engine at 8psi of boost"? AFR is irrelevant if you are over-advanced and detonating (and NO YOU WILL NOT HEAR IT!) As TimZ says, you likely won't like your compression check results. My forecast is Cyl 3-6 have uniformly dismal compression from broken ring lands due to prolonged inaudible detonation. (AFR does not shield you from detonation.) Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 I will check compression when I get home if it's not raining. I'm curious to see. I'll update soon. Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 (edited) Cylinder 1 135 2. 132 3. 135 4. 125. With oil added 125 still 5. 135 6. 140 This was done cold at 60f at full throttle. The gauge was hand tightened. What do you guys think? Car runs well except for being rich at idle. Edited April 20, 2015 by grillhands Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 20, 2015 Share Posted April 20, 2015 Could be a bad PCV valve. Here's the basic concept. Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 I replaced the pcv during the conversion. I'm not sure what's going on but I think I'm gonna vent to a CC then send it to the atmosphere. I'll cap the pcv. Or just maybe my dip stick was shot and needed to be replaced lol. Quote Link to comment Share on other sites More sharing options...
malibud Posted April 20, 2015 Share Posted April 20, 2015 That looks good on the compression. mine were around 105 +- 5psi hot and varied more when cold Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 20, 2015 Author Share Posted April 20, 2015 Tony D got me nervous about turning my engine into shrapnel so I'm probably gonna dial down the timing. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 21, 2015 Share Posted April 21, 2015 That is a little steep. My max map was 24 psi at 8psi but that was on Japanese Gasoline (dashracer 104 octane) When I got to CA it would rattle on 87, and 91 so I had to back it off again some more. That was 8:1 CR Build though, not a 7.4...though that doesn't seem to make much difference. The compression looks OK, a leakdown test would be a good thing to verify engine health. Putting a manometer gauge in the oil cap will let you know what kind of crankcase pressure you are building up, it shouldn't be appreciably more than a few inches of water at full load and full rpms if everything is evacuating correctly. Even with an open upper cover and everything blocked it should blow out any excess pressure to meet that criteria. If you are getting enough pressure to push out the oil dipstick, something sounds plugged. Either that, or put a catch wire on the stick and lag it down when running. Though if there is pressure, you will start to see oil leaks... Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 21, 2015 Author Share Posted April 21, 2015 I ordered a new dipstick so when that comes in I'll be taking her for a run. I'll keep an eye on the rear main seal and the oil pan gasket. If I have to change either one then I'm gonna pick up a 5spd while I'm down there. The 4spd stinks on the highway. As for today, I'm going to check the pcv again but I'm not too sure where else to look for clogs. Quote Link to comment Share on other sites More sharing options...
510six Posted April 23, 2015 Share Posted April 23, 2015 Turbocharged big boost air cooled VW's used to launch dipsticks, a standard fix was to put a spring on the dipstick... they leaked oil anyways regardless. I had a similar issue when running a very large shot of nitrous with a turbo L motor, the solution was to use an aircraft style air/oil separator with a drain back with a 5 micron filter to the oil pan below the oil level a friend who was an aircraft mechanic suggested the solution and it worked like a charm, as I recall we used a Isuzu Diesel fuel filter housing and other than the drain back to the tank it was similar to the link below. http://www.autospeed.com/cms/article.html?&title=DIY-An-OilAir-Separator&A=110826 Tony mentioned something potentially clogged, I have seen the thick metal screen that is inside the block become clogged especially when a high paraffin oil was used . On your next oil change pull the pvc breather tube from the block and spray some carb cleaner into the hole I have had success with 4 cylinder L motors that were acting like the PVC was clogged . Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 23, 2015 Author Share Posted April 23, 2015 I'm going to install this seperator today. I'm going to run the crankcase hose to the inlet then run the outlet before the turbo so there is constant pull on the crankcase. I will be changing the oil today so I will spray some into the block. Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 28, 2015 Author Share Posted April 28, 2015 In 5 days I collected this much crap. This is way too much Quote Link to comment Share on other sites More sharing options...
grillhands Posted April 28, 2015 Author Share Posted April 28, 2015 What do you guys think. Quote Link to comment Share on other sites More sharing options...
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