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Greetings,
well, the turbo conversion on my 87na 2+2 is complete. finally.
that being said, I just wanted to talk a bit about it. long story short, some minor problems during the project that were unexpected, but resolved with slight modifications. will talk about these items later.
as far as running and performance, it runs. a few issues exist however. turbo spools up nicely and no strange abnormalities during acceleration accept for a few hesitations that I noticed, thought very short. the idle is not very good, and I'm still trying to tune it and make adjustments. some of the issues that I am attempting to correct:
engine does not start initially after sitting cold. I have to crank it several times before it will start… I believe this is due to the 84 ECU and the lean/surge problem that the early Zenki cars have.
for a test, I swapped back to my 87na ECU and she fired right up, no excessive cranking or hesitation. didn't idle well of course. plugged the turbo ECU back in and same thing happened -hard time starting.
once it warms up, it seems to start and run fine. I have sourced out an 87T ECU that I am going to use as I think it will be a bit more compatible with my setup, plus it will give me a spare.
hopefully the no start issue goes away.
timing and idle. I checked my idle timing and it is sitting right around 25 degrees BTDC according to the marks. 87na and 84-85T application calls for 20 degrees. the 87T calls for 15, all +/- 2.
so, I plan on setting it to 15 when I get the 87T ECU. I'm hoping to see a better idle and smoother running. I have the turbo idle control valve installed, but the idle seems to stay high (above 1000) and seems to fluctuate as well, but when the a/c kicks on it goes down to about 900. still high. for testing purposes, I am thinking about removing the valve completely and them see how it will run. I just want it to be steady with no hesitation.
oil and water temps. the cooling system was replaced with as much stuff as I could possible replace or repair while the engine was out. so far, so good. the temp gauge stays on the cool side and barely even got up to mid temp even after an hour long freeway drive. I did install a 160 degree T-stat in hopes that it will open quicker during the hotter summer season here in the UAE. one thing that I did change (and I was very hesitant at first) was going from traditional 50/50 green to BMW blue coolant. this was not an easy decision, but based on my mech's recommendations for the best cooling possible, I am trying it. I was reading some stories and hearing awful things about the new orange Dex-cool (Dex-Kill) and was horrified to learn that they use it a lot over here. apparently some folks have had damaged cooling systems after using dex-cool and so I have decided I will never put that in my car! maybe its only good for the newer GM vehicles? I don't know. anyways, the green pre-diluted coolant is not the best quality here, so I'm sticking with the blue. so far, so good. btw, the new dual core turbo radiator seems to be flowing and cooling nicely, much more so than the single n/a core that we pulled out of the car… I am truly amazed that it lasted this long and that I drove through three ridiculously hot summers with it and it still managed to keep things cool. based on visual inspection, looks like a factory original from 1987. dinky thin core too. again, amazed at its longevity.
oil seems to be holding up well. now that my oil temp gauge works due to a new OEM Nissan sensor installed, it hasn't gone past mid-range during driving. I fear that it will however when the summer comes.
I'm not using an oil cooler, but I think I may install one at later time depending on how the temperature goes. I do smell of hint of burnt oil after running (I don't know if this is normal, but I smell the same thing on my 280z NA2T as well) I hope the oil is not getting cooked in that turbo. is this normal?
performance overall. its not as powerful as I thought it would be, however this could be due to the turbo being a TB250 which came from the JDM VG20ET engine. I don't have a boost gauge as of yet, so I don't know for sure how much boost is going through. I can say that it does spool nicely and pushes hard when I open the throttle. high speed pulls on the freeway seem strong. its nice to have the extra boost, as I was not able to gain much extra power going that speed (120K/ph - 140K/ph) with the N/A. the pull feels great, even for a stock setup with stock boost.
one thing that does concern me, is if I really get on it and rev high during boost, I can hear a slight rattling sound… like taking a soda can filled with small pebbles and shaking it, the best way to describe it. I'm not sure if it detonating as I don't yet have the ear for it, however it only does it when its boosting and at high RPMs. (I am new to turbo driving, and still learning how to drive it properly, so please forgive that)
I read another post about some guy/kid who blew his motor up by driving like a maniac at high speeds, so I don't want to end up like him or his car.
no offense, kid.
exhaust. nothing to complain about really. I got the 2.5 turbo back from CM with the dual muffler pipes. I didn't go 3" because I was only wanting a stock setup for my car. I did however go with the off-road pipe and do away with the CAT as it is not required here for emissions, however I am coming to regret this, as the system is loud at freeway speed with an unmistakable "drone" that gets annoying after a while. I might change this and go with a high-flow CAT from CM, if it will quiet things down some.
final thoughts. though I am happy with the setup, it is taking a bit to get used to. I have found that as far as drivability is concerned, I have traded comfort for speed. I like the extra power and get-up speed, but I do miss the comfort factor that my car had when it was N/A. I never once had trouble starting, or ignition issues, or idle issues. driving and shifting was more smooth and comfortable. my car may not be very comfortable during long drives and doesn't seem to be as reliable as was before. that being said, I don't regret foregoing the comfort in exchange for power.
in hindsight, financially-wise and reliability-wise, it may have been better to have just stayed N/A, and just repairing the cooling system and getting a good 3" cat-back exhaust and enjoying the high compression, zip-around-town, smooth driving pleasure.
I am still in testing phases, looking for problems, and observing the behaviors of my car and its new setup. I am hopeful and optimistic that it will not experience any major problems or have a catastrophic failure.... but if that does happen, well, there are plenty of RB motors sitting around that I could try
Your thoughts and observations, please.
Cheers,
Bon from Abu DhabiLast edited by bonfire79; 02-16-2017, 12:38 AM. Reason: additions -
The cat is only going to stifle performance and do little to reduce the noise.
The car is detonating. You will melt your pistons soon if you dont stop beating on it and address the issue.
"I can hear a slight rattling sound… like taking a soda can filled with small pebbles and shaking it,"
This is detonation.
You need an intercooler, higher octane fuel, and possibly 1 step colder spark plugs. -
You need a boost gauge yesterday. It's vital. I'm trying to find someone to rebuild my motor due to detonation. I never heard a thing but I'm now blowing a quart of oil through my exhaust every 150-200 miles. I was running too much boost. Shouldn't have gone over 10 or 11 lbs. I wouldn't even get into boost until you have an idea of how much you're getting.1986zxt w/ '86, 56k mile, na engine (turbo bits swapped), K&N intake, 3" CM Performance turbo-back exhaust, Eibachs, KYB shocks, Front Mount Intercooler (2.5" plumbing), Turbosmart MBC/9 lbs, recirculating BOV, ASCO plenum, dual fans, Maxima alt, Champion 3 row Radiator.
2013 Ford Taurus SHO Performance Package -
Gentlemen,
Thank you for your replies.
86T, how did you know the engine was detonating? I mean what happened, did it blow and seize up during driving, or just stop working? I am getting a boost gauge ASAP as I want to know what this turbo is running at. I don't think it is any higher than a stock T3, but maybe it is. I don't hear it over-boosting at all… it just spools up like normal and sounds normal (no strange noises or fluttering). will find out more once the gauge is hooked up.
Max Birdy, I got NGK plugs for the turbo car when I had my engine rebuilt (when it was N/A). I am not sure if these are the cooler type. I am running the highest octane fuel available over here which is Super 98.
and the intercooler was going to be in the baby-step process after the initial turbo installation. trouble is finding a decent kit that won't break the bank and can fit in the Z31 with ease. I was thinking about just cutting a hole in the fender and routing the pipes that way and using a recirculation-type blow off valve (I don't care for the sneeze sound during shifting).
this will clutter things up, but I'd rather run cool, safe, and cluttered rather than hot, broke, and sorry.
the rattling sound is not loud. its very subtle and only occurs when pushed hard and at very high rpms. it doesn't do it during normal take-off boost and normal driving conditions. only when I really get on it.
I am going to adjust the timing down to around 15 or 13 and see how it does. it may help with cold start and idling issue as well.
I wish I could really capture the sound on it. I might try and secure my GoPro cam in the engine bay and maybe I can get a good audio of the noise. I'm not driving the car daily… just during troubleshooting and testing during my time off.
Thanks for the info, guys. Will keep updating.
Cheers,
Bon
Last edited by bonfire79; 02-24-2017, 01:21 AM. -
Back timing down to 15*. The rattle sound you hear is detonation, from either running out of fuel up top, timing to far advanced, or the air temperature in the cylinders is too high.. You also need to install a wide band. Keep it up and a sparkplug will break and damage a piston. Worst case is you melt a piston or valves and have a loss of compression as a result.
1986 300ZX Turbo…sold
1990 Skyline GT-R…new money pit
2014 Juke Nismo RS 6-speed…daily -
Hi Egg,
Thank You for the reply. I understand about the dangers of running it and doing any damage to detonation. as of now, i'm troubleshooting things in it's covered parking spot. trying to get the idle valve where it is supposed to be, working on a new turbo ECU, and i'm going to adjust timing this weekend. I'm going to back it down to 15 degrees and see how it runs and then make a short boost drive around the block. maybe, the detonation sound will go away. i thought about using wide-band, but then I thought it was only with a management system installed?, like NISTUNE. how can I manage the monitoring of it without having NISTUNE or other FMS? right now i'm using the Zirconia sensor that came off the turbo car. will a wide-band be compatible fit-wise and ecu-wise as the stock sensor?
Thank You.
Bon -
Wide band is separate from oem sensor. You drill hole in downpipe and weld in bung for the wide band sensor. It is basically for you to see what the car is doing really time while driving. You can use a wide band with Nistune to eliminate the oem sensor. It is safe to have a wide band installed on any turbo car regardless if it is stock or modified.
1986 300ZX Turbo…sold
1990 Skyline GT-R…new money pit
2014 Juke Nismo RS 6-speed…daily
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