KCIR today-new PB-13.158/104.1-it's time to tune it!
 

Another beautiful day in Kansas city - mid 60s and partly cloudy. I had set my second-stage fuel jet to 22 from 24, and wanted to test things. Here's a summary of my times - and a surprise. All runs 75-shot + 75-shot, 3300 lbs on the line, with spare tire and jack.

Shift_Fast....6400......6400......6400........6400 ........6300

R/T...........-.105........163......-.003.......-.202.......-.014
60'............2.055......1.918......2.038.......2 .026........2.057
330'..........5.622.......5.403.....5.601.......5. 597........5.666
1/8...........8.576.... ..8.372.....8.589.......8.589........8.673
MPH..........83.37.......81.24.....81.28.......82. 27.......11.278
1000'........11.145.....10.971....11.192.....11.18 1......11.278
1/4...........13.317.....13.158....13.382.....13.370......13.477
MPH..........104.66.....104.10....103.93.....103.86......"50.38" - bogus speed

driver/passenger tire pressures
Tire.pres..18.5/22.5...18.5/22.5..15/15.....18/18.......18/18...

On the fifth pass, the nitrous tank was getting empty, and time was running out, so I put the car back on the trailer.

With the re-jetting of stage two, my trap speeds went up, traction was still lacking at launch, and I had forgotten to set tire pressures until someone asked what they were. I should have left them alone.
:nod:

Congrats on the new best, Harry. It sounds like you've got tuned pretty good seeing that you ran a new best in far worse conditions (1800' DA today). Sorry I didn't make it out. I've spent all day doing "homework" because things have been so nuts at work. I guess I'll see you at KCIR next season or maybe in December. Every once in a while they'll be open for runs in December if the weather is good.

Hi, Dave B , you missed a pretty good day in the sun.... The tower said that they would be open next Sunday if the weather was OK !!! Guess they have some hot dogs and beer to sell...

Leaning out the second stage did give me some top-end, it seems. There's more there if I can figure out the 330' issue with lack of traction.

I am glad the second stage is working better for you. Any ideas what the a/f ratio is? Also try launching at lower rpm and if that dont work try a lower pressure for the slicks. Maybe 13psi.

I'll have to get some dyno time and tune it the right way.... A/F = ??

I do launch at 2800 w/the Edge TC. That worked better than the stock TC. I've tried lower tire pressure and no change - I've been down to 12psi but just lost steering control and stability.. 15psi is stable at launch, at least... No combination of launch technique and sprays seem to make a difference. :wtc:

Running w/ 18.5 psi in the driver's side and 22.5psi in the passenger side tire seems to work the best... :bustrun:

Maybe you are not warming the tires up enough.

awsome new times. If you got urself a wideband you can be alot quicker and defently get deep into the 12's. You can probably slightly lower fuel pressure just a tad bit to lean out ur n/a mixture therefore leaning out nitrous mixture. or you can do the same u did with the second stage and lean out the 1st stage as well. but not untill you get wideband or dyno.

I wouldnt touch first stage. The fuel setup is good on that stage. Its the second one that needs work. But yes hit the dyno to see what you are getting with the second stage. Also I believe that you are using the same slicks that jime used to use and I believe that he used to get the air pressure down low to get them to hook well.

You might be right - the slicks keep pulling me out of the water box, even with the rear wheels locked. I usually can't get a long burnout, just some smoke, although when I come out, the car leaps out hard. I just can't keep it there very long.

This track is kinda casual on T-n-T days, and the water "strip" gets spread out some. I watched a turbo Honda do the same thing - his rear wheels were locked, but his slicks pulled him out of the box and into staging - with the rears locked.

I did wipe down the tires before each run with acetone - partly to get all the rocks off, and to "sticky" the slicks. The pits and staging area is asphalt, but small rocks are everywhere....

I'm going to order some VHT for wiping down the tires....

I wonder if using a common nitrous feed tube for both stages is dragging down the amount of nitrous actually getting to the nozzles - I plan on running two of the new solid feed lines (in parallel) from the trunk to the engine, so hopefully I can keep pressure up at the nozzle. I use a heated 15lb bottle in the truck so that pressure doesn't drop much during the 1/4.

Once I do that, then it's off to a tuner dyno shop for dial-in. Just changing the second-stage jet from 24 to 22 raised my trap by 1 1/2 MPH. Obviously there's work to be done here...

I think the line is maxed out for 150 shot. I am pretty sure that you will either need a bigger line or hook up the second bottle for second stage with its own line. Thus each bottle for each stage. I think that will help a lot.

I think your lack of traction is due to having too short of a slick and too much air in them. 18-22psi is insanely high for slicks in my experience - and I have a bunch of it from my NA car. I ran my M&Hs down at 11.5-12psi hot.

I can't give any real advice as to how to size the slick for your auto because I have no idea where different size slicks would put you at with your gearing further down the track and I haven't run any CarTest sims on it, but that is my hunch. Taller slick and less pressure = better times for you unless it severely screws your gearing up top. What RPM and in what gear are you crossing the line?

EDIT: I made this post assuming you were spinning wildly in the first 330' - then I realized you never stated whether or not you are spinning your tires like crazy or not. If they are NOT spinning, then ignore everything I just said above.

I would also try to replace the air in yout slicks with nitrogen. I believe jime tried it and it would actually hold pressure a lot better. Like Neal said, lower your pressure to 11-12 psi. Ask them if they could put extra water int eh box when u pull up for your burnout.

I agree, i think taller slicks might be worth a shot. on 22" slicks on auto would go into 4th gear before end of 1/4. dont kno if with the shiftfast mod he can stay in 3rd. but gearing might not be hurt too much since he can rev out each gear lil more than stock shiftpoints.

1. Tire pressures - I have usually run between 12 and 15psi - I forgot to check tires last Sunday, due to drama with another racer, but first two passes were with the 18.5/22.5psi imbalanced tires. The second one of those produced the 13.158 ET. Go figure. I went to 15 psi - no improvement. Went to 18psi - no changes. Go figure. 12psi makes the car "bulldog" - shake it's head on launch - 12psi too low to drive safely. Slicks spin and shudder. Wrinklewalls are wrinkled from tread to rim, and I swear the car drops lower.

2. The 23/8.5/15s give me a good low gear to launch and I still go into third gear at 6400 well before the traps. Dunno trap RPMS - never looked. A taller tire would leave me in 2nd gear at the traps - bad idea. With the MEVI/Ingen intake, HP does not drop off before 6500.

3. Slicks are spinning and pulling hard at launch, spraying 75-shot right after launch, goes to second stage right after first stage, Shift_Fast shifts to 2nd at 6400 and cuts 2nd stage at that moment, continue to spray 150-shot combined through traps, Shift_Fast goes into 3rd gear at 6400 w/spray-cut at shift. During the 2nd pass, the 13.158 run, I drifted badly to the right, I assume because tires were spinning madly. I have tried using just 75-shot through 1st gear - went slower. Haven't tried just a 75-shot pass - probably won't try it.

Remember, this is Test-n-Tune track prep, which usually means one cleanup and VHT spray before runs begin - and that's all. I've run on well-prepped tracks - this wasn't one of them.

All ideas/suggestions are welcome - probably, some I've tried or some I never though of or understand yet.

???

Nitrogen supposedly stabliizes pressure when hot - a good thing. I would have to locate a source of nitrogen - M&Hs leak a lot.... I've tried 12psi and found that pressure too low to drive safely.

The extra water is a good suggestion - I noticed there wasn't much wet left there after a few passes by others - probably why I couldn't stay in the waterbox ????


I'm leaning toward a rubdown with VHT before every run. More sticky than the track can provide....

Nope - see above. I need more traction. Wider slicks? not available in 22-23" diameter. I can build the MSD Shift_Fast to shift all four gears at any RPMs, but why?

Maybe 28" slicks shifting at 5000 ?? I've done better by letting the Shift_Fast do its thing at higher RPMs, with the smaller tires.

I tried the 255/50/16 BFG DRs, since they are 26.1" diameter and 9.7" on the ground, but they just spun and smoked - they did NOT like the 2nd nitrous stage,. spinning up to 3/4 of the track.

???

I think i know the solution to your problem.----> NX Maximizer. although im not 100% sure how it works, but you can program it to spray progressively instead of instant burst of tq and hp n make u spin. Jime can give you more details on this.

Also, what is your suspension setup. You might want to consider workin on that, Do you have your illuminas adjusted to the most stiff setting? Maybe use zip ties on the front springs to keep front end from lifting at launch (few guys do this and say it works.) also theres this rubber pieces you can put on your rear springs to keep the rear from sagging when launch. Slicks and Power is not always wat gives you the best time, suspension is very important. dont know wat your setup is though, but im just saying what you should look into if u havent.

The Maximizer has its' own problems, like pulsating solenoids wearing out - committing to a preprogrammed spray program doesn't let you drive it. I looked into that, and chose not to make my life more complicated.... this is the guy with no A/F meter, remember? :naughty:

My suspension is already set up for zero movement on launch. The car doesn't move up or down (unless the slicks "bulldog" w/low pressure).. It's been this way all this season. Traction bars are preloaded, Illuminas are set to maximum dampening, and the rear is set higher with multiple pair of rubber blocks. Plus the rears are set to 35psi = no bounce in the rear and no lifting of the nose.. Launches are ....very abrupt ... :doublethu

Actually, the car drives very well this way - I really want to put the big DRs on the front and go to Heartland Park next season for some roundy-roundy track experiences - I wonder if I can use nitrous on the straights ??? Heh. :chebosto:

The Skip Barber Racing School was a lot of fun a few years ago - maybe the Road Warriors biweekly track event would be fun, too....

OK fine i guess you've covered everything n shut me up lol. At least im on the right track to knowing how to set up the suspension. :rollsmile

It was a good point to cover - but I already had it covered....

But when you get serious, you'll need to do the same things. An important part of solving your problems is to ask the right questions ("what are you really trying to do here?") and then finding the answer - or answers - until you solve the problem. Then, "repeat as needed" until you're in the 11s. Then you can buy a BB Chevy and head for the 10s or 9s. :nervous:


Last Sunday, two new modified Z06 'vetts checked in, rumbling and shaking, and ran each other. I heard the times on the radio station, and one ran 13.04 at 106 and the other was 13.11 at 104. Maybe on a good day, I could beat either one! Not bad for a stock-bodied furrin' car with a junkyard motor and tranny, eh? With "MAXIMA" spelled on the rear window with shoe polish so the tower knows what kind of car is whipping up on the locals..... :woot:

23's are too small for you. I know how it is (gearing vs traction) but I just got TIRED of the 23's when I had the 3.5. A set of 24.5x8 would fit much better on your wheels, raise the front end somewhat, and provide more traction and consistancy.

You may have a point - I see M&H makes the same slick in 23", 24.5" ,and 26". All fit on a 15x8 wheel, and are identical except for the diameter. Hummm...

If I don't do the 3.5L conversion, but install long-tube headers feeding the 3" Warpspeed cat-back and ditch the 3" W.S. y-pipe, what's your opinion about the slicks then? By the time I update the nitrous plumbing and dyno-tune, there will be some more HP there. Adding headers over the stock manifolds will be worth a little more, I think.. Traction would be a bigger problem..

Of course a 3.0 on spray will never have the brute HP of a 3.5, but all the work won't be wasted when I replace the 3.0 with a nice fresh 3.5.. :bustrun:

Try spraying first stage after you get traction in first gear. Basically like a 1 second delay.

nice job, did try a run with just the nitrous changed to see if you were getting better nitrous pressure then a 2nd run with the fuel jet changed to lean it out.

And maybe for better traction you could try leave on the motor then go right into the nitrous

I've done that - most every combination you can do - and as soon as you hit spray, I light 'em up... which is what slicks are supposed to do - I'm just not hooking up well - most of the time... I wonder about track prep..

Only thing that helped was changing the 2nd stage fuel jet from 24 to 22. That really helped the top end. That, and having the Shift_Fast shift and switch off the second stage when shifting..

Maybe you are over geared? Anyway I wish someone would do cartest with your slicks size, rpm shiftpoints, and power that you are pushing.

hey remember the header and 3inch exhaust will free top hp upstairs + with the leaned out 2nd stage this will help and allow you to pull the taller gear(24inch tire)

The slicks are 73" circumference, the Shift_Fast changes gears at 6400, and:

According to the Maui HP calculator: http://www.mrp.org/

"Horsepower Results - 1/4 Mile Method

Your nissan maxima weighs about 3300 pounds and can complete a 1/4 mile in about 13.158 seconds. That means that you've got about 286.31 HP at the wheels, and about 372.20 HP at the flywheel. "

Don't know how accurate this is, but there it is....

That sounds pretty accurate a bit low if anything. I dynoed n/a 167whp, then sprayed 50shot and gained exactly 50whp putting me at 217whp (without bottle warmer). so assuming i sprayed a 150shot like you, that would put me at 317whp, and the torque, through the roof!!!! almost 400lbs probably (wonder why you spin so much :bowdown1: )

Yep, HP don't work good if you can't hook.... So close to the 12s, too.. I want to clean up the nitrous feed line issues and then dyno-tune the car. Maybeeee try a 175-shot at the same time, if plugs look good on the dyno. I can always load the smoking wreck back on the trailer if things don't work out jest right..

speaking of dyno, i will be doing dyno this Saturday. going to do 3 pulls. im going to dyno all motor on the first two to see where my new found uber n/a power is at :doublethu and then make few adjustments and spray 75shot on the 3rd pull. just for show, since theres going to be alot of skittles there (wanna shut them up since they always talk sh!it cuz they feel threaten) :)

I really think the slick diameter is too small, resulting in too much torque multiplication and thus wheelspin. It seems you have the suspension as optimized as it'll get, etc. I think you are overgeared. If you know of a dyno you think is similar to what your car puts down I can try to cartest it.

Good for you - this should be a great learning experience. Dyno pulls take most of the random stuff (like burnouts) out of the picture, and leave you with the hard cold facts...... Note: be sure the car is strapped down tight, and tire pressures are equal. Tire slippage happens with a casual hookup, and that blows your numbers out the window.

Please share what you can - there's always something new to learn.....

I think I agree about the tires' diameter - just hitting the first stage spins them up, and using the second stage in first gear doesn't really move the car much quicker in the first 330'. That's my clue that tires are not hooking well, except for the rare occasion when they do hook - then the car pulls a lot harder in the 330'... :nod:

I'll have to do a dyno next, after I change out the nitrous line from the trunk. I did find the cartest module last night, downloaded and installed it, and played a bit. I used the existing 1995 Maxima Automatic and set some of the numbers to match tires and Maui-calculated horsepower - kinda cool to watch cartest showing massive wheelspin at launch. I played with the Optimize function and it kept telling me to launch at 700 RPM instead of 2800 RPM, which creates the wheelspin. The 24.5" slicks helped some, but not enough to really matter - 800 RPM launch indicated. Obviously I don't know what I'm doing w/cartest, but I may have to re-think my entire launch process.... :hmmph:

When I ask jime for some tips in the other post, he posted that he launches from idle spray right off the line

this does not help you since you already have the high stall converter

That was his old car(s), betcha... He's got a 3400-stall converter now... Most serious folk seem to do a TC mod.

If you keep the 3.0+spray, 24.5s.
If you do a 3.5 with 3.0 timing chain and ECU, 24.5s still.
If you do full 3.5 with 02 ECU and VTC+spray, 26s.

Thanks for the advice - and without your Jbars, we wouldn't be having this conversation ! :ben: