Scottie-GNZ

Nice going!! For others looking to match that, note the 60'!!

Hope I did not muddy the waters and since pictures tell a story better, here is what the spreadsheet would like and the corresponding graph showing the fuel curves. Do not take these numbers as gospel!!! I just quickly put this together as an example. In the spreadsheet you see RPM and Fuel values that would be programmed in the RPM FUEL map. In the 3rd column you see the % increase for each increment. The value of 122 was derived from the table above based on 290cc injs and 466cc cylinder displacement. Everything else anchors off that number. Note that there are no dramatic increases in fuel in this map as it is strictly for "normal" driving. I never used the TPS and would add just a little extra at the off-idle point for a crisper response. If you use the TPS, the SDS will handle that for you. Remember the TPS is only used to trigger a little extra fuel for off-idle (at least in the model I used). The SDS compensates for increasing RPMs and that is why this table looks so flat. Do not make big incremental jumps. In the 4th column I used an anchor number of 82 based on 466cc cylinder displacement and 440cc injs. I then applied the % increase number in the 3rd column to the anchor number in column 4 and let it generate new numbers for the map and round off those number. Next to the spreadsheet is the resulting maps visually and they are identical. Every other fuel map, be it for boost, cold start, etc, is also anchored off RPM FUEL. IOW, "add fuel to RPM FUEL to compensate for boost, cold start, etc.." So, do not change those other numbers initially if you change injs. Get the car to idle smoothly, have crisp off-idle and accelerate normally w/o boost by tuning RPM FUEL. Once you get that right, then program the others as needed.

Unless the concern is for brakes and suspension, the massive torque of a turbo engine makes the extra weight a moot point. If the concern is for brakes and suspension, I strongly recommend they be upgraded anyway to match the increased power.

I know you have the HP to do it but until you have that little piece of paper........ So, whats holding you back? Fear? :D

You say you are using a GM shaft but what u-joint are you using on the diff side? The NEAPCO adaptor I am referring to used the big u-joints on one side and bolted up to the R200 flange. I doubt that it was made specifically for the R200 and it is more likely that some other application uses a flange with the same bolt pattern as the R200. Rather than tell them R230 (HUH? WHAT?) you need to take an R230 flange in to them and have them find a u-joint flange that has the same bolt pattern.

I was waiting to give someone else a chance to jump in and relay their experience. All SDS fuel programming anchors off the base number derived from a combination of the cylinder displacement and the inj flow rate. The trick is how to maintain the fuel curve after generating the new base number. Here is my trick: Create a spreadsheet that has 3 columns: RPM, Fuel Value, % Increase. Put the RPM increments in the 1st, the fuel value for the corresponding RPM in the 2nd and a calculated % increase for each increment in the 3rd. Next, add a 4th column for the new fuel value and go to the matrix below and figure out your new base number. Put the new base number in the cell that represents 500 RPMs for your 4th column. Next, write a formula in the cell below that one that will increase the base number by the % increase in column 3, then copy that formula in all subsequent cells in the 4th column. You have now generated the same fuel curve using the new base. The new values will definitely have fractions, so round accordingly. Of course, if you are unfamiliar with spreadsheets, then what I just said probably means nothing Couple of things to keep in mind. Build the RPM FUEL curve to match the torque curve not the HP curve. That means your values should basically stop increasing after 5000 RPMs. DO not use the RPM FUEL map to compenstae for lack of fuel under boost. If you do, you will also have that extra fuel when not under boost. The numbers are not cast in stone so further fine tuning will be required. I have never been able to get a L28ET to idle correctly with the base number so play around with the number to get it to idle correct but still use that number as the anchor for off-idle and above. I suspect most of the time the idle problem is air leaks wanting it to idle richer. HTH,

I am using a custom 3" shaft with the Spicer joints and not having any problems. Only difference between the shaft I have now and the shaft I used when I ran the R200 is that the rear flange was a special NEAPCO adaptor to adapt the Spicer joint to the R200 flange.

That's crap unless it was meant to be a joke. jgkurz, your mistake is running Nissan u-joints. Since you have a GM tranny, have a 3" diameter shaft made with the big Spicer u-joints and have them put the NEAPCO adaptor flange on the end of the shaft. That adapts the big Spicer joint to the R200 flange. I forgot the part# for the flange but the driveline shop will know it.

NOT QUITE! It all depends on what terminology you use and how you define compression. Remember that for every 1-bar of boost, a turbo car has the potential to ingest twice its displacement. Lets say you are able to ingest twice the displacement, that means at 14.7psi boost the 2.8L has 5.6L of compressed mass stuffed in the cylinders. From a physical standpoint, the c.r. is still say 8.0:1 because of the physical displacement differences of the cylinders between BDC and TDC. However, think about the mass that is actually being compressed (remember, that mass is already compressed) and believe me, you have the equivalent of more than 8.0:1. I would venture a guess it is more equivalent to 13+:1. Ever wonder how a hot L28ET with lots of boost can have 450lb/ft of torque? Probably because it is stuffing the equivalent the of almost 7.0L of compressed mass into its cylinders and then compressing that mass again. As for the final drive ratio, Z-Gad is correct in that a turbo engine works best when under load for longer periods. That does not mean load as in dead weight . The actual ratio you need depends on the RPM limit of the engine, MPH thru the traps and the ability to spend a longer time in the meat of the torque range in each gear. A low-torque, high-revving turbo engine will demand different gearing than a high-torque, low-revving engine. The L28ET with the stock cam is not a high-revving engine despite many making it out to be one. It is pointless revving it pass 6000RPMs. The more boost you run, the more torque you make, the higher the MPH. With that you usually end up with less gears in the tranny or a lower numerical gear ratio or get the engine to rev higher. A perfect example of this is 240Z Turbo, when he ran 129+ with his 3.1L, he was pushing the engine upwards of 7200. I rarely push my engine pass 5700 (only 300 less that what a L28ET should run at) and at those speeds or higher, I run a 3.07. Granted, I have more torque, but if I was revving my engine to say 6200, I could and would run a higher numerical ratio.

I will give you a "success" story. I used to cut low-1.60s with 275x50-15 BFG and Nitto DRs and even had a couple of 1.55s with the BFG (good conditions and track prep). When I upgraded to the C4 IRS I needed to switch wheels for the 5-lugs and to fit over the big Vette brakes so I decided to go with 17s. 17x8.5 all around with 225x45-17s and 275x40-17 Nitto DRs in the rear. BIG MISTAKE!!! If I try to leave with any power at all, I could spin them up to the 330' if I wanted. I still need the big DR for a rear tire on the street because of the car's power, but I must say going to 17s was (FOR ME) an absolute waste of time and money. They do look cool, but I am one of those "function before form" guys and cool to me is blowing someone's doors off at the line. Having no choice, I switched to using track tires only. I ran a 26x9.5-16 Hoosier QTPs on 16x8 Z-28 and my 60' was back with consistent hi-1.40s to lo-1.50s and a couple of freaky 1.45s. After those wore out I switched to 27x11.5-15 QTPs (these tires are HUGE!) on 15x8" Draglites that just barely fit over the rear brakes. Last Wed I cut a 1.39 and a 1.41 and if I was running a solid rear I would probably have lots of air under the front tires. Zero wheelspin. NADA. BTW, I also run 25x4.5-15 Moroso skinnies on 15x3.5" Draglites. You said you are a straightliner so the questions are: how quick do you want to go and how much are you willing to compromise and sacrifice? The optimal setup is something like what I run but I absolutely do not recommend you drive with those on the street. If you have stock fenders then you have a limited choice in DRs and the BFGs are not a good street tire. My Z can be driven anywhere but it is not my daily driver and I do not rely on it for everyday driving. Lucky for me, the local track is only 9 miles from home on mostly backroads so I switch tires at home and drive there with the race tires. When I have to go race out of town, I have to rely on someone to go with me to take the race tires. Bottom line is, if you have serious HP and you are serious about going quick, then tires are critical. It is not about big or wide or what looks cool but about compound and the highest profile. Yep, the higher the profile, the taller the sidewall, the better a soft compound tire will hook.

I know this will probably generate hurt feelings, but lets be honest here. Let's see a show of hands of all the Zs and ZXs in the 10s with an L28ET, regardless of setup.

Welcome L-B. Just spent a week in Gainesville recently. I come up every year for the PLM at Road Atlanta and prefer to stay in Gainesville.

1SickZ, I can bring a spare if you are definitely coming, otherwise I do want that thing flying around loose in the car. Look forward to meeting some of the new folks in the area.

I plan to test my car this Wednesday night at Orlando Speedworld and maybe the Orlandoans will come out and meet each other.

That was your big mistake. Get a SS Dynomax Ultraflow and if it is a bit pricey, get the aluminized version. Try to get a minimum of a 6" tailpipe on the muffler.

At the Petit LeMans event at Road Atlanta last week, Jim Downing was there with his LMP675 powered by a 2.6L quad-rotor rotary. It made the most glorious noise but was slow as sh*t.

Whats wrong with zipties? Bet I have at least 25 under my hood.

Vast difference in their HP potential. If you are looking to go really quick but cannot afford to convert it to an intercooled setup, then I say pass.

Please tell me that comment was joke! BTW, a hybridZ is any Z-car that now has an engine it did not come from the factory with.

My springs are so old I do not remember the spring rate but I am sure it is in the 200# range. I bought my Illuminas from shox.com.

Mike, I think your problem is that you are probably unloading the rear tires too quickly.

Stony, you have it correct. I am having good success with Illuminas set on #1 (softest) setting when at the track.

I would think there is a higher demand for a quality, well-priced fiberglass hatch.

Think about this. There is actually a guy out there that looks at that and gets a WOODY!

Those numbers are in line but only if you can get the car to hook up. Forget it if you plan on trying with street tires.