My 1990 300zx Twin Turbo build by megaDan

9 minute(s) of a 731 minute read

First off, I realize I'm doing a crappy job of getting pics up. The car isn't that nice looking, but I still haven't got a shot of it fully assembled.

During the week I performed a boost leak check and had to use....unconventional methods to stop the airflow. I couldn't find anything in my garage with a 3" OD. So mayo had to do the trick. The only boost leak I could find was around the VTC solenoids. I must not have sealed them up enough when I checked the head stud torque. This required me to pull the plenum after getting everything set up and plugged in. Luckily this didn't take too long. I know I've done this probably 50 times at least now, but I'm still amazed I got all the vacuum lines and electricals hooked up without any mistakes on the first try. And no boost leaks after removing ALL the intercooler piping.

I put another two hours yesterday and two hours today getting everything wrapped up. I attempted to put the bumper on yesterday but wasn't able to as the air filters got in the way. I had to adjust the positioning of the recirc valves and all was well. The bumper went on smoothly and I managed to not lose any additional screws! I didn't put TOO much time in yesterday as it was my moms birthday and for the first time I decided to check out the 24 hours of Le Mans. Never watched it before, and realized I'm missing out. Since I don't follow racing it was mostly a bunch of people I've never heard of driving around a track I've never seen, but it was a ton of fun to watch.

I got up early this morning to watch the end of the race, and went back in the garage to finish attaching the bumper and get the oil changed after a winter of sitting. Nothing unusual this and no problems. Yay! That doesn't happen often. I do have a power steering leak though. I took the time to clean up everything below the car to see what was leaking, and I think I need a new PS reservoir. Damn.

I got the car warm, checked for leaks, didn't see anything too drastic, I think much of the oil is from when I pulled the valve covers originally and made a mess. This morning I went for a drive, pulled over when the car got up to temp...and saw some smoke from right around the PS turbo. Uhoh, and I didn't have my extinguisher with me. I got home and popped the hood and got a flashlight, and it looks like it was some oil that collected on the top of the turbo and had been sitting there. Later in the day I went for a longer drive, and the smoking was gone (after wiping everything down with carb cleaner).

BUT, when I finally mustered up the courage to get on it a little bit....the car hit about 5k in first gear and lost power. It ran fine part throttle, but once I hit boost around 4k rpm it felt like I hit a wall. I thought it was a problem with the recircs, but when I got home I discovered some hose clamps had moved on me and it was likely just massive boost leaks. I moved some piping around (some hoses and clamps are not at ideal angles) and I think I've got it squared away. The car runs great, I still have that annoying rattle with the clutch in or with the car in gear....but the engine itself runs great. I can't wait to get this last bug sorted out and get it tuned. I know my current tune isn't really adequate anymore and I would really like to get everything dialed in asap since its so late in the year. Time to look into area dyno's!

OH boy....

It's been about a year since my last update, and life has only gotten busier.

I finished last years upgrades mid summer last year and got a little enjoyment out of it, sold the mini in October and rushed to find a car before the snow fell. Ended up picking up a 2002 Jetta TDI that just put down 53.5mpg last tank (if I say 'put down' it makes it sound like the car could be enjoyable).

I got the car on the road a little later than planned this year, I got the car out of storage in early April to replace my rear main seal due to some slow oil drips and the rear DS tie rod needed replacing (4 wheel steering!). I had some hiccups with the RMS (forgetting protector plate AGAIN, ugh) even with a helper. It's not just me! I didn't get to the tie rod, because while the trans was still on the ground I learned I had 9 days before Ztuner was coming to Chicago for a dyno day. But I DID swap to a 12lb flywheel. I put the car back together ASAP to start testing the car to make sure everything would go smooth for the tune I've been waiting years for.

The tuner requested I do a WOT pull ahead of time so he could have maps ready when we got the car on the dyno. I obliged and to make a long story short...found out my current clutch was incapable of holding my current power levels much less the gains I expected to see. I tried adjusting the clutch pedal and didn't see any improvement. Ugh. 2nd day aired a much improved clutch for alot more than I wanted to spend and did the entire swap in under 3 hours, with my girlfriend helping get the trans down and myself doing the rest. Not bad! The clutch was in on Wednesday, and the dyno day was saturday...cutting it close!

I took the long way down to chicago to break the clutch in, and drove it as much as possible during the week without getting on it to much. 300+ miles without a single issue was a good sign. I wasn't able to find new plugs at the suggested 7 heat range, so I stuck with the NGK Iridiums I've been using. When we got to the dyno saturday at 8am, we saw many familiar faces. My buddy Pat tagged along (who had a slicktop Z32 which inspired me to buy mine) and the guy who organized this turned out to be the guy Pat sold his Z to...and it was there with a 800hp ethanol burning VG30DETT. A guy I had met before had some spare plugs, and the tuner suggested I swap them over, which was done in short order. The first car up was running a setup similar to mine without the 2.5" intercooler piping and without the massive intercoolers and he put down 415whp...impressive!!!!!!

I went second, and immediately started misfiring. After an hour of troubleshooting we swapped plugs and found TWO of six brand new plugs to be cracked. Yikes. Everything went smooth again until I blew a vacuum hose off at 13PSI, the car has been run up to 18psi on the street before with no issues. I guess the dyno really IS quite a bit more stressful on the car. By the time I was done I finished with 427WHP 442TQ, a little disappointing as I was hoping for 450+. And I didnt't seem to get any gains at all from the 2.5" piping, I've overlaid my previous dyno plots and the powerband doesn't seem to have shifted to the left at all. However, I'm super pleased driving the car, the power comes on MUCH smoother now and it pulls much harder. I've gone from 12/15psi on the EBC to 14/18. 14 is plenty 99% of the time, as if the tires aren't warm and the street isn't warm, the tires won't hold above 4500RPM in 2nd.

We stuck around to help a few other cars get their issues sorted out, and the potential 800hp ethanol monster wouldn't start with its new wiring harness. We ended up leaving at 1:30AM the next day completely exhausted with Pat's old slicktop on the dyno, but still having issues even idling consistently. The day was an absolute blast and I'm so happy with how the Z has turned out. A little frustrated at the power level and lack of improvement, but at the same time....I don't have to worry about it any more...I'm done doing power mods, and almost done modding the car itself. I've been cleaning up and powdercoating tarnished items in the engine bay and I have new leather bits waiting for the interior. Eventually when the suspension starts to show its age I'll bite the bullet and replace it, but as of right now the only changes on the horizon are lightweight driveshaft for next year as my carrierbearing is showing a slight amount of play and HOPEFULLY new seats. I swapped to a spare DS seat I had that is still torn, but in much better shape than my old one. I'm really looking forward to just pulling the car out of storage the next few years and driving it...without having to change anything. And hopefully get decent gas mileage. The tank I got dyno tuned on was 20mpg, some highway, lots of WOT pulls on the dyno, and lots of WOT pulls on the street. Hopefully I can get in the area of 22-24 now that everything is leaned out a bit.

I'll get some pics up soon with the items I've been powdercoating and new dynoplots so everyone can see the changes.



Might take a little bit, work has been crazy and with all the rain I haven't driven the Z since it was tuned