Afshin

Obviously running rich won't make it safe is timing is high. The post asked about afr's. And there are reasonable guidelines for AFR's assuming reasonable timing and vice versa. If you run richer, you can advance timing a little more and if you retard the timing you can lean it out a little before getting detonation. Also, you can't find the limit of timing without proper afr's first. The timing you have seems reasonable, I pull back timing from about 2 psi boost to end up with total advance of 20 by 12-13 psi and keep there until max boost of 16. I find setting reasonable timing as you have then fine tuning afr's works well. It's hard to fine tune timing as well without a dyno or perhaps an accelerometer, if you are patient. An egt gauge could help as well. I would do as you originally planed and borrow the WBO2 meter, fine tune the afr's they play with timing again. I had to keep going back and forth with different combinations to find one I liked best. I now plan to get an egt gauge in addition to my WBO2 to help me fine tune my timing and afr combos, as it gets very difficult to fully optimize the set up once you get a decent tune. After that I may take it to the dyno to see what happens with different timing and boost combinations....

If going up to 15-16 psi boost I would definitely use 93 octane only. A tune with 91 octane and 15-16 psi will have to have very high ign. retard or excessive fuel to keep detonation at hand. Going from 12-13 psi up to 16 requires a lot more fine tuning than going from 8 to 13 psi, at least in my experience. The higher octane makes it much easier, I tuned my car at the safe limit for 15psi with 91 first and with 93 octane and back to 91 octane. The 93 tune was much much better as I could have a more reasonable timing curve and afr's. The cars detonate mostly at peak torque, which is often in the early 4000 rpm range. For my car I get the afr to high 10's little before peak torque from about 3700 to 4500 rpm and keep it in the 11's otherwise (only when boost is over 11-12psi). I think twelves may be to risky, specially for high boost in the 4200rpm range. However it may very well work fine before and after that critical point. Obviously each set up, turbo, boost gauge, WB02 meters are a little different...But generally afr of 12:1 at peak torque and high boost is too lean, 11's is a good goal, 10's provides the best safety margin but at the cost of less power. Running 10.5:1 for peak torque rpm range only has turned out to be a good compromise for me who is stuck with 91 as my daily gas. My current set up for this tune consists of: a healthy but stock engine, T3-T4OB, good intercooler, 440cc injectors, SDS fuel/ign system I recently got, 3"exhaust, BPR 7 spark plugs and the car is set up for street and demanding open track events....I hope this helps as you fine tune your set up. I got lots of useful info from Bernard and other HybridZ members which made tuning my car much easier and faster.

You're right bastaad, the 20-30 hp gain with better exhaust in turbo cars is mostly due to increase boost. More often when boost is kept constant before and after the exhaust, gains are more in the 8-10hp range, at least in the 2 tests I saw in some of the magazines. Off course that increase in efficiency has many other gains as you already pointed out.

Thanks Cody, the last pictures were very helpful. I need to get to the junkyard some day and compare some parts off the 300zx , toyota, with the 280zx....and see if I can do something similar to what you did, but maybe with a caliper with larger brake pads... I will certaintly post it, that is if I actually ever get to do it (I always have more plans than time)

Very very very nice!!!!!! I just love seeing this engine being used more in the Z's. I think it is a perfect match. Someone you should be selling mounts for this. You must be loving the ride

I'm using a 79 280zx 130mph speedo unit I picked up from the junkyard for $15 . It also reads about 5mph fast, works great and very easy to do.

I need a little more info before putting in my 2 cents: What octane do you run California 91 or non Cal 93-94 ? What are the ambient temperatures (Canada vs. texas....)? What is your fuel system? What temp range spark plugs and lastly is it only street driven or does it see track duty?

Hi Scottie, do you know if your downpipe had enough clearance for the 280ZXT?

If I were in his shoes I would not run less than 89 octane. California gas quality is lacking and so. cal. is warm enough. The savings from 89 to 87 is not worth the risk in my opinion (think hot day, someone in integra or golf pushing your buttons........fill in the blanks), even if you are broke. However I don't have first hand exprience of 87 cal. octane damaging a stock set up. Nor would I try to obtain the experience

Thanks for the pictures Cody, looks good The rotor appears significantly larger than the 280zx, it should improve the rear braking torque nicely and help it better match the new large front rotors. Would you have a photo of the caliper mounted to the bracket (from behind the rotor) ? Keep us updated.

Hi Vinh, I also just checked your web site, beautiful car and nice craftsmanship. Hey Yasin, have you mounted your downpipe and high flow head yet? if not I would be glad to help you out by taking them off your hands. I will have them on my car within 1 to 2 weeks max. Hint, hint

Hi John, the stoptech article is a nice one, I have a print out and had posted the link for it here on HybridZ a while back. The interesting thin when I got the wilwood rotors, is that they were warped brand new, before braking in the pads (so I could not have screwed that up). WHen turning the wheel after the install the rotor would touch the pads at the same point (like a warped bicycle wheel), I thought it was related to the pistons not being set in since I had not driven it yet. Then on the first drive around the block it knocked so hard I thought something was broken or that I forgot to tighten a caliper bolt..Made sure the hat/rotor bolts were properly torqued (they were done in proper sequence) and all was seating properly....Took it to the shop and indeed the rotor was warped, we turned it and it fixed the problem. I was quite surprised.

Hi Cody, glad you got the car back on the road. I absolutely love the big brake set up. Feels good every time. BTW one of my two rotors needed extensive turning when new. Also, I have noticed that the wWilwood calipers are pretty good at trapping air, specially as the pads thin out and the pistons are extended out. Make sure you tap on the calipers when bleeding them, it often can help dislodge some trapped air. Also don't forget to set some toe in on the rear suspension, it really cures the tendency for excessive throttle oversteer and stabilizes the back when pushed. Regarding pads I had a set of Portefield R4-S (aggressive street pad with reasonable track ability in a light car with big brakes that run relatively cool) which where pretty good. I recently replaced them with Hawk HP plus (real track pads, but not serious race pad and safe for street/cold use....) I was told that they work great but generate more dust and noise. I figured I would give it a try and if too much (I hate noisy pads on the street) I would use them on track days only. However, much to my surprise, not only did they work better than the milder portefields R4-S pads, as expected, both hot and cold, but they generate no noise whatsoever with my Wilwood set up (lots of grease on the back) and I can't notice any significant increase in dust. I have not had them long enough to comment about rotor wear, however with the big brake set up on a light car (that is compare to modern day cars, not a 240), I would not expect too much wear. Jon, if you don't mind what has your experience been with the pads? Lastly Cody, what happened with the rear brake set up?

I have always been a turbo guy and love high revving engines such as in the M3 and S2000. However, I certainly would not call anyone with a clear preference for high displacement engines as lazy. The whole point for grown men and women putting so much attention, time and dare I say affection for a silly machine is enjoyment. The instant kick and response from a V8 is always a blast and can generate a smile I would never tire from it. Yet, for me, building the power in a turbo car or a nice high revving engine (not a civic) helps me better connect with the machine and as such greatly enhances my driving experience. For others, powerful immediate thrust is the key. On the same token I love open track events and attempting to learn to balance my car's handling thru 20 minutes of high speed turns. In short, I somewhat prefer the element of pushing and controlling the car thru turns than pure push me in the back of the seat thrust, though I certainly want and appreciate both. Others get more kicks out of faster quarter mile runs (again more thrust). Some people prefer foreplay as for them it increase the ensuing pleasure, for others it is a distracting to the main event and a nuisance Calling a group lazy based on what gives them the bigger kick, to me shows a myopic perspective. Heck, if immediate kick and power puts the bigger smile on your face, IMO, you would be plain stupid to drive a S2000 and wait forever or having to drop two gears before you can accelerate. It's not about connecting with the machine, immediate acceleration, quarter mile runs, open track events, handling, low end or high end thrust...it's simply about what give you the most fun and help relieve the stress and or mundane routines of daily life. Failing to see this as to why we make different choices and have different preferences, would be a shortcoming.

I find it odd that the car went from 15-16 psi and no detonation to 10 psi with detonation because of the better breathing and less backpressure from the new downpipe. Specially when as Bernard pointed out JWT usually run on the rich side with AFR’s in the 10’s on boost. Even if the car was is now in the 11-12 afr’s because of the downpipe…..it should not detonate at 10 intercooled psi. I still agree with all that has been said, however I would suggest you try a few things first and systematically before you get your hands on a wideband O2 and the rest. My recommendation would be, in order: -Use up the gas in your car and fill her up from another station. Bad gas really does happen, and it could cause your problem. -Clean the ecu/efi connectors and so on.. it is a old Z after all -Re-gap plugs around .25-.30 -Use the seafoam (I know that is not the main problem, but it has the potential of significantly helping, should you have carbon deposits..) -Drive the car and see how she does. -Then increase fuel pressure in step. Never fully trust a new gauge, my brand new autometer fuel gauge reads 5 psi high so 40 is actually 35….. Keep making it richer by increasing psi by 3-4 lbs and then drive it and see if the detonation goes away. I f it is running rich and still detonating, it is less likely to be from fuel and JWT code. You changed the fuel regulator, so maybe this is your problem. -Then retard timing a few degree and see if still knock, then retard another few degree and test it again…., then you will have a idea about potential timing problem It won’t cost you anything to try these, and at the end you may end up figuring out the problem or at least better ruling out potential sources for the premature detonation.

The turbo suspension was a little better tuned. Interestingly as mentioned the springs where a little softer than the n/a, but the shocks were firmer as were the bushings in the rear control arm (so the ride was actually a litle firmer). Also the front anti-sway bar was larger by 1mm (23 vs 22mm). However, the original spring/shock rates for both cars was suited for a big sloppy 4 door sedan and not a sports car. They should not be used!!! Get a set of performance springs and shocks and replace the bushings. The only part worth taking of the turbo car is the front sway bar.

I wonder if they sell nomex boxer shorts What is the primary intended use of the car ? daily driver, street warior, 1/4 mile, opent track.....

It would be great if you made and sold the mounts, driveshaft.....the 7mgte is such a great engine and unlike the RB25, is quite cheap and abundant in the US.

when you say you swaped the harness with a 300zx one, do you mean you cut the wires before the ecu connectors ans soldered them to the 280zx harness vs. switching the entire harness....

Shauno, PLEASE be more considerate and post a WARNING for any such posts, e.g. not for those with weak stomaches, or have bucket handy.... I gagued and almost puked all over my kid. I will have to take some anti-nausea medication before looking at some of those again. To think that they pay to have that done and drive around in them, simply unbelievable!!!

The widest wheel I have heard for a stock 280zx are: 18x8.5 front with 245/40/18 and 18x9.5 rear with 285/35/18 these were from a guy in NY. Unfortunately I don't know the offsets he used. According to him these where the absolute widest he could fit. I believe him:)

Do unto others as you would like done to you.... I guess I have no choice but to reciprocate all that love!!!

Reference list of specs such as offset, lug patterns…..for all factory wheels http://www.discountedwheelwarehouse.com/Vehicle_Bolt_Pattern_Reference.cfm Long list of various wheel weights (slow site)... http://wheelweights.net/

If you want to minimize the body roll you need to get the sway bars, they will do much much much more for this than the strut tower bar (no comparison whatsoever). Also the rear strut tower bar will have very little effect on a ZX. The front one does help. Also I would nor worry to much about the squat, it does not effect handling nearly as much as you would think. DOn't forget to change the control arm BUSHINGS, the car will NEVER handle the way it is supposed to with 20 year old soft bushings. Changing to stiffer springs than you already have, IMO should be the last thing you try, if the goal is to improve handling in turns. Off course if you had the stock springs they I would recommend changing them first.

Grassroots motorsports mag had done a review of 4 wideband units including the LM-1 and the PLX units (I have one which works great and auto calibrates, which is why I chose the unit). I don't remember all the details, but the good news is that they found ALL of them to work VERY well (when calibrated, if needed). They also tested a narrow band unit which as expected faired very poorly and had very wide variance (non-repeatable) in addition to being inaccurate.