Afshin
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Posts posted by Afshin
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I'm using 280lbs/in front and rear springs rates and find the ride to be significantly better than I had expected. This is using a s13 stance coilover set up which I feel to be excellent dampers, that I modified for my 280 ZXT.
This car is a little more set up for track use, but it's still driven on the street. Ride on regular roads/highway is excellent, gets reasonably bumpy on some city roads, but still acceptable and with sufficient travel to keep good tire patch contact on uneven roads. I also feel that the dampers affect the final ride more than spring rates (within a reasonable range).
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I have also been using the superlites (same size pistons) with various Hawk pads over several years and have only noted minimal pad taper (approximately 1mm). I have not rotated the pads nor have I had any issues. Would buy them again.
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What are you goals for the car (daily driver, weekend car, track ...) and what's your approximate budget?
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The adapter for the miata is for a 10/1 fitting.
I was told and hence always thought that our cars also used 10/1 but I see that you said it is 10/1.25. If so, then I would be in error about the miata kit fitting our brake lines directly (I have not checked myself and was about the get the adapter from flying miata, so I can't confirm).
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You can get the adapters from flying miata:
http://www.flyinmiata.com/index.php?deptid=4539&parentid=0&stocknumber=14-76240
They stock the part now so you don't need to be part of the group buy anymore
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It's because side wall stiffness affects the tire patch size, independent of weight and psi, that it would cause some inaccuracies. Since we can't measure the stiffness, we can't account for it. Just picture a run flat tire that will maintain a decent contact patch at 10 psi to a rated H tire at the same psi, it would significantly affect the weight estimate.
I do agree that careful squaring of the cardboard to ensure accurate foot print measurement is likely the most important variable.
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Cool idea!
Temperature should not make at difference as it effects psi linearly and is accounted for in the calculation. The main variables that I can think of are tire side wall stiffness, distribution of pressure through out the carcass and measurement error in taking the actual foot print for each tire. Based on these we can expect it not be very accurate for total weight.
However most variables are fairly constant between all four tires, so this method could potentially be very useful in figuring out corner weight percentage, notably for those with coilover set ups. I will have to try it.
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I recently tried different potential fun and practical daily drivers (used 2004 to 2007 models) including some of the above mentioned one, here's my summary:
WRX (2007) and mazdaspeed 3, thought the speed 3 was more fun and responsive (less lag) and handled better (in stock form) but the wrx AWD power delivery felt better than the FWD (which I'm biased against). THe wrx would need better springs shock and then should handle appropriate to its well designed chassis.
Also test drove legacy GT (2006) and mazdaspeed 6. Liked both quite a bit but was not happy with gas mileage on legacy GT. Also thought the speed 6 handles better, at least with stock suspension.
Comparing the speed 3 and 6, the 3 is a little quicker and spunkier (weight related) and the 6 is more refined, subtle, better chassis feel, suspension with AWD vs FWD which is why I preferred it. If you don't mind FWD I would definitely go test drive the speed 3.
Comparing the legacy GT and WRX, I preferred the GT, all the fun but nicer interior, quieter and less of a police magnet. The wrx has advantage of greater availability and cheaper.
ALso tried 2004 BMW 330i, liked it, did everything well as expected, nice balance but also less exciting. At the end of the day, I'm a turbo junkie.
Also considered the Audi, but the reliability seems to be hit and miss. Many people like them but I know of enough who were unhappy with reliability).
I ended up buying the speed 6 about 3 months ago and absolutely love it. Only thing I did not like was the power drop off after 5500 rpm (from electronic throttle programming from factory, the ecu starts closing the throttle past 5500 rpm even when pedal is to the floor) which I remedied with a COBB re-flash, making the car much faster (much more power at high rpm, not much difference in peak power). Same applies to the speed 3.
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The mkIII intercooler is quite restrictive to flow. Turbo magazine had a review in the late 80's. I believe they found it to have close to a 3 psi drop at around 7 psi manifold boost. So you need to make 10 psi at turbo to get 7 out. That' quite a loss. This does not mean that it does not work, as plenty of people have used it successfully, including myself (I had a lightly modified mkIII). So if you're on a tight budget and already own it, its reasonable to use.
However if you keep pushing the car, bigger turbo, more boost.... as many of us do, it would be worthwhile at some point to replace it with one of the newer cheap and fairly efficient aftermarket intercoolers that have become widely available over the last 5 years or so.
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I also run a T03/04E 50 trim, 0.63 A/R with SDS fuel spark management.
Will it does spool to good psi at reasonable rpm, it is really slow before that. In other words it start spooling late but then ramps up quickly. This is in comparison to my previous T3/T4 with a stock turbine. SO boost come on about 300 rpm later, but feels like its' off by 500 or more rpm. Using this configuration for open track events, i find the lag a little excessive and modulation of power in the 2500-3200 rpm range a little tricky.
As such the car is much faster on the street, but not on smaller more technical tracks. This problem would only be amplified for an ATX set up.
Of note, a main problem with my set up is that I'm still on stock cam and the mismatch with the turbo is quite noticeable so as the turbo comes to life by 2000 rpm later the cam chokes it (I have 3" downpipe, good intercooler....). I can feel that the turbo has so much more room to go on the topend as opposed to my previous one which did not want to go past 15 psi as effortlessly.
In short, I agree with your thought process and would not lose sight of sacrificing top end power for a wider power band for any car aimed at autocross and would keep linearity of spool up in mind (to allow for proper throttle modulation) as well as what psi can be achieved at a certain rpm. In general, I would avoid larger turbine set ups more so than larger compressors (I wish I had spent the extra money for a BB turbo).
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I believe some of you are looking at the s13 stance photos of the rear unit which has the top adjustment knob. The fronts s13 have them at the BOTTOM of their inverted monotube.
I can definitively tell you that the pictures from AZC pdf http://www.arizonazcar.com/coilover.html are IDENTICAL to the stance units that I have bought and modified to put on my car. I actually followed some of his instructions when putting my front coilovers on, but with a different adaptation to adjust for the bottom knob (I used a flexible steel cable welded to a socket as opposed to the rubber hose that Dave used). I just want to point out that my claim is that they look the same, have the same knob, same nut under the knob and same number of adjustments. This does not guarantee that they are stance and as I said stance may be getting their components from Bilstein as may be other companies.
Clifton do you know for a fact that they are not stance or are you saying based on photos you saw?
If they are truly not stance, then I would surmise that this other company and stance might be outsourcing from the same company.
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They look like Stance units that he may have custom ordered. I bought a set for the 240sx (S13) which I have used and adapted to my 280 ZXT.
The strut housing, adjustment knob shape and 15 point adjustment all point to that as they look identical to mine, as far as I can see from the pictures on AZC how to install pdf.
The camber plate is his own and hence different, as may be the anodized perche locks....
Now regarding stance, they are excellent for the price, as far as I can tell (researched them for some time before buying the units) and have been told by a semi-pro racer and experienced custom fabricator at the track (no not John C.) that stance uses a custom ordered re-valved Bilstein unit. Considering their performance on my car, I certainly believe it. I was amazed of how reasonable a ride I could get, in face of ridiculously stiff springs, when paired with high quality dampeners. Their performance has been equally impressive at the track, but I have never compared them directly to other similar grade set ups on my car. If I'm correct, I imagine you will likely be quite happy with AZC's set up.
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OK so I have a nice offer for ya friend, how about $5000 cash, as-is, no questions asked, but only because I think you’re a nice guy…...
(It’s going to require a lot of discipline to slowly break in the engine)
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Well the tuning process has progressed nicely. It felt like the engine was bogging down with the large #10 nozzle combination and 50-50% mix, so I switched back to the #5 nozzle and set it to start injecting sooner at about 2-3 psi (after realizing that it was previously starting to kick in at 6-7 psi). The results have been quite good and the engine is more responsive, with no pinging at 22 psi boost, which is quite wicked, to say the least. I turned it back down to 18 psi for daily driving and engine longevity. I also took the car back for a full day at the track and it performed great! I think I will stick with the current tune and 50-50 mix for now.
In short, water/alcohol injection is simply amazing for our detonation chambers. Perhaps I can go ahead with building a higher compression engine
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Excellent results !! (though I always figured you had to be over the 400HP mark).
Nice to see the stock intake able to support so much HP at high RPM, even considering the extensively worked on head. I imagine that turbo can shove in quite a bit of air to make up for some of the restriction.
What about the exhaust manifold, is it still stock?
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boost set on "absolutely freaking kill"
I can imagine you hitting maximum psi and grinning ear to ear in a cloud of smoke as you disappear into the horizon. BTW, regarding those furry creatures crossing the road, there are better ways to hunt.
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The devil's own unit I have has a led light that lets me know when the pump starts kicking in and then also when it's at maximum output, which is quite nice.
There is a company that sells pressure switches to let you know if there is actual flow through the line:
http://www.enginerunup.com/shop.php/parts/injector-nozzle-pressure-sensor/p_13.html
Generally I'm not so worried about failure of the system as it should be no less reliable that the fuel injection unit. So knowing it's on and reading boost is enough to make me comfortable. We can just as easily have a fuel injector that flow less than the others causing lean conditions and loss of piston....
Bo, do you have an estimate of how much methanol you are injecting, such as 15 or 20% of fuel flow ?
According to general guidelines I should be using 12.5 to 25% water/meth or 1-2 GPH per 100 horsepower which comes out to about a 4 to 7 GPH for my application.
Bernard, you are running a LOT of meth, but in your case it seems to be more of a hybrid gasoline/meth fuel system than a traditional Meth/water injection system as a means to prevent detonation on a gasoline fuel injection. Obviously 50-50 mix would not work too well at those volumes.
Texis300, 50-50 mix is generally believed to be a good way to get both cooling, detonation control and good power output. It's clearly the mix most recommended by various manufacturers. I would recommend that as the starting point.
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Well you guys are certainly making a good case for 100% methanol. One thing that made the various tunes for me a little more work pertained to the fact that SDS does not have memory for different maps and I must manually reprogram each time. For changing peak timing, I can do it very easily, but changing the fuel curve is more of a pain in the neck. On track days I need more flow as the car is pushed so much beyond street application, requiring a different tune. With less methanol, I was able to make changes in other parameters (flow, boost…) with less retuning. But then I really have not tried that many combinations yet, which is what prompted me to ask about others experiences. I guess I could keep playing with it on 50-50 mix and then when happy with the tune re-try 100% meth from a better platform.
Bo, your set up sounds real nice. How did you choose the flow amount with the constant cycle pump set up? Did you pick a percent of the fuel injector flow? Do you approximately know how much meth you are injecting (in GPH or ml/min) at 15 or 20 or any given psi?
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I have a meth injection kit which I’m in the process of tuning for my car (work in progress). I have seen highly significant differences in nozzle size and tunes and wanted to poll members here regarding their set ups and see if we could share some info in an organized manner:
Application: open track (and street)
Engine: l28et
Turbo: T3/T4 50e
Boost: 16-20 psi
Fuel system: SDS
Air fuel ratio: ~10.8-11.1/1
Spark plug: NGK bpr 8
Timing at max boost: ~22
Meth injection: Devil’s own progressive unit
Start injection at 5 psi and maximum flow by 17psi
Nozzle size: M10 (10 GPH; 630ml/min)
Fluid: 50-50 water/methanol
I recently tried 100% meth, which has yielded good performance results for some members, such as Bernard who runs very high meth flows, aiming primarily at peak power for ¼ mile applications. However my goal is more for detonation suppression and combustion chamber heat management on longer open track events. So far, I found 100% meth to require a significantly different fuel curve tune than 50-50 mix (which can run closer to a non-meth fuel curve tune). I also drive the car on the street a fair amount and don’t want to run 100% meth at high volumes all the time and would like the flexibility of decreasing meth injection volume when off the track without having to re-tune the car…so I have switched back to 50-50 mix, with good results. Regarding nozzle size, I first ran a 5 GPH nozzle but still had to be very careful with timing advance, as I could get brief knocking and then switched to a M10 with good detonation suppression, but can’t tell if it’s larger than needed and have not tried any other size nozzles yet. It would be interesting to hear of various experiences with different nozzle sizes, tunes, mixtures….
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I also remember K-mac making a kit.
I have two SPC/MSA kits installed on my car, which have been critical for properly setting up my suspension. However, I think that slotting might be better and certainly easier. I also have continual rotation of the bushings (I marked the spot for proper alignment with white paint and then re-adjust once in a while, easy to do). Lastly, make sure you slot for toe adjustability and replace the bushings. A little bit of toe in (1/8-1/16") in the rear of the 280zx does wonders (actually it's a must in my opinion).
Here are a few links on slotting you can browse through:
http://www.az-zbum.com/modification.adjustable.camber.shtml
http://dimequarterly.tierranet.com/articles/tech_crossmember_slotting.html
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I got this digital gauge on sale from harbor freight for $15 (~$25 with shipping and tax..)
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As already mentioned in the thread, the 300zx harnesses appear to have better connectors, which are a common source of poor connections and EFI related "gremlins" in the 280ZX. So despite the easier/cleaner fit of the 280zx harness, I would select one from a 300zx, if starting from scratch.
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I bought a Forge unit after looking into various unit with little objective information at hand, despite much searching. I have a MAP based EFI and run my BOV as open, but got a recirc unit to ensure that the outlet was solely designed for flow and not noise generation. You can certainly hear it from inside the car as a whoosh but nothing loud, which was my goal. Had it for over a year now and can recommend it. Came with 3 springs and hence good adjustability, solid built and excellent customer service. My friend got a similar unit for his supra after my positive experience and is also very satisfied with his purchase.
S130 Suspension Tech
in Brakes, Wheels, Suspension, and Chassis
Posted
I don't mean to imply that the Tokicos are not good. I had the somewhat standard tokico/eibach combination for many years and was certainly satisfied with them and think they're appropriate for a street car with occasional light track duty. You would get your money's worth out of them.
I upgraded once I started to spend more time on the track. Suspension is mostly about balance and proper set up for each intended use, which is why it's soooo much trickier than increasing power/boost for example. When I first put my coil over set up it felt better (less lean and play..) but I also think it was slower around the track until I got to tune it some (change my alignment settings, camber, height, sway bar...) and then it finally performed better. So in short eibach/tokico is a reasonable start along with new bushings. I'm a fan of Bilstein's, but have not seen them for a stock ZX.