I am very confused about my car right now. I had put quite a bit of money into the car and it seems like it was wasted eventhough I thought that what I was doing was well thought out and researched. With my car modded a 98 ITR with Skunk2 Stage 1 cams, cam gears, Kenji ECU, VAFC, AEM CAI, SMSP header/cat, custom 2.5" exhaust I ran the following quarter mile:
90 degree night 205/50/15 falken azenis @ 22.5 psi
R/T ... .531
60' ... 2.33
1/8 ... 9.477
MPH ... 73.44
1000 ... 12.28
1/4 ... 14.67
MPH ... 91.56

Now with my car almost completely stock, AEM CAI only on a 100+ degree night (hottest night of the year) my car ran the following:
R/T ... .621
60' ... 2.35
1/8 ... 9.55
MPH ... 74.00
1000 ... 12.65
1/4 ... 15.07
MPH ... 92.3

Now my question here is how can this happen? how can so many other things be almost equal and a car pull 4 tenths of a second but actually be going slower? All the runs were done absolutely full throttle thru the finish line. No letting up and all the shifts were clean. I am just a little intrigued. The car was fully dyno tuned. We spent almost 4 hours on the dyno (with wideband O2) tuning things and I left the place with a very linear power band. I was just wondering anyones opinion and/or suggestions. Might there be something wrong with the car?


[Modified by 98 ITR 815, 1:36 AM 10/6/2002] some people were missing the dyno tuning part


[Modified by 98 ITR 815, 3:49 AM 10/6/2002]

 

hmm. that really sucks dude.

today was my first time at the track and I did quite well. this is in quebec city. dunno the elevation but i think it's medium high up.

my best run was

reaction : 1.095 (i wasn't ready... really =P)
60' 2.333
1/8th 9.584
1/4 14.771
MPH 93.950

This is on a bone stock 2001 itr.

 

You gotta launch higher then, those 60 fts aren't too great, people have doen 2.2's with stock tires at like 25 psi, with 22 psi you gotta launch high and hard and try slipping the clutch really nice also, gotta stay in the vtec, your temperture obvoisly affected it your tiems big time also...way too low mph. Gotta get some 2.1's or even 2's with those tires and thats really possible also, just practise makes perfect...make sure your swiching gears right at red line also of course, yo should of gained way more time off the quarter mile, ive seen 4 tenths off it from like intake and header and cat easily....no exhaust even most of the time...jut those things...

 

your 60 ft is for sure killin you, they are the same with falken and stock almost, lol, gotta rev high with those tires for any differences at 22 psi i hears its like 7500 rpms to launch good and cut some 2's or at least 2.1's...i run my stock tires that are balding osrta at 22 psi and on good road like ashphalt and i gotta rev to like 6-6.5 rpms so i don't bog and get a crazy launch....like i said tho the hot weather is also affecting your times a hell of a lot and elevation too maybe, maybe theres something worng with the car but i dunno bout that...probably not, its the launch for sure tho....

 

With the stock car I was feathering the clutch off of a 6000 rpm launch rpm. If I dumped that high I spun all the way through 1st and bogged hard core in 2nd. On the modded car the torque was too much to launch that high. The car would spin the tires launching in the 6000rpm range so I ended up feathering from a 5000rpm launch rpm. ON the modded car I could go way past the stock redline if I so desired. However, shifting much higher than 8800rpm (stock tach indicated) netted slower times. With the stock car I shifted right at the fuel cut (8600 rpm indicated)

IN the stock car I actually got a 2.20 60' with those tires; my time at the 1/4 was faster but the mph was right about the same... actually a little slower. I didnt feel it was as good a representation in this particular post. The almost identical 60' times give a better estimate of how the cars are pulling on the top end. I wanted a good comparison. I realize people have gone faster and that I could in fact get faster times with this exact setup what I am wondering is why the trap speed fell but the time got faster? I was wondering if something could be wrong


[Modified by 98 ITR 815, 1:57 AM 10/6/2002]


[Modified by 98 ITR 815, 2:00 AM 10/6/2002]

 

ouch that trap speed hurt!

i hit 94mph with my vtec half working(no engine oil ) and running a 15 flat

 

Bad luck, maybe the car isn't running right, cause the times should be MUCH faster than that, way to low of mph, it must be wether and elevation for sure then....

 

.elevation of the track is around 900 ft. If there is something wrong with the car that would atleast explain something to me. As it is I am baffled I just want to know what is going on.

 

I'll have to find my slips, but I've done 14.48 @ 98mph with just an AEM CAI and no ps belt, everything else stock(A/C, full interior, on 15" Toyo T1-S). 2.3 60' is average...should be better with Azenis I would think. How are you launching, how were the track conditions(surface wise), how were your shifts? Also were you spinning the 1-2 & 2-3 shifts?

 

Tuning man, tuning.

 

I described the launching technique above. I was spinning the 1-2 shift slightly, and chirping the 2-3. All the runs were very consistent with the car in both states of tune. I also have the ACT Extreme pressure plate (had to go with the Extreme it was an emergency and it was the only one available) and SS disc clutch.

I dont know how you can just say tuning.... We were on the dyno and changing anything just didnt help. The cam gears like to be where they were (ended I +2, E +0). Setting the timing higher than 16 degrees netted big losses. Tuned the fuel curve and that gave me a horsepower here or there. The VTEC changeover ended at 5000rpm and that gave me a really smooth transition. For the amount of time we spent tuning we got very little. And everything WAS TUNED, I am not the kind of guy to throw something in a car and expect it to work. But I do expect a gain from the amount of money and work I put into this engine. Now that it is through with I just want an interpretation of the data. What went wrong, if it went wrong? What should I have done differently? etc... I just need to learn from this and so far I cant take anything from it myself. Like I said before I am at a loss, just looking for some answers.

 

Ok man, sorry but its one of 2 things then, one get a better 60 ft first, should hit 2.1's at least depending on track of course i guess, second maybe something is wrong with the car, cuz those are kinda bad times, its one of those things then, or maybe even both...

 

try to up your tire pressure to 32-33psi.. - might help a bit with trap speed...

what was your a/f ratio on the dyno and maybe top hp/tq? maybe you ran too lean once on the street?

 

I don't get it why the times are so slow with all those mods?

 

hmmm...i hit a 94.6mph in my gsr w/ a cheap intake and an old skool dc 4-2-1, something is definitely up w/ ur car...

my car had over 100K miles too

 

Definitely the 60'

 

dam you should be lauching higher..... may be some thing is wrong with your car .... with all those mods you should be running atleast high 13's... maybe its your clutching .... never know

 

Get the car dynoed, Your trap speed is very low. You can launch harder and use sickey tires , But the trap speed isn't going to change. With the mods you have you should be 100MPH + . Get it Dynoed!

 

It was dynoed. Re read the opening post

 

Yea i saw you run at Fireturd last week,and was SHOCKED to see how low your traps were.That was a BAD WEEK though for everyone i know.My friends were trapping on AVERAGE about 3-4 mph lower than they normally do in their Si's.(88-89 mph vs the normal 92-94 they normally trap at) Wierd night at Firebird,thats for sure.

 

98 ITR 815, what were your dyno #s after the tunning?your 60ft times are poor ive pulled better times on my stock michellens,but one thing i have come to learn about the drag strip is that track conditions can make or break you i would go back when the weather was a little nicer an see how you do before you get to upset about this an mabe drop the pressure on thoose tires next time also,but i reall ythin kthat that 100degree plus temp made a diffrnce.with my old car i went to teh track on a winter night where temp was probly around 40-50 i ran 14.0s went back with better tires on a sumer night here in FL where temp was probly around 85ish with really bad humidity an did no better then 14.4s

 

i would like to know what your shifting at, being i feel your prolly getting excited and either shifting too late or shifting too early, and not staying in ideal power band! And around every tenth improved in the 60 foot, is around a tenth and half in the 1/4!

i would also like your know your dyno numbers!! good luck, eric

 

I think you guys are taking my question a little off topic. I am really not worried about my 1/4 mile time. What is eating at me is that I improved .4 of a second and was going slower on the top end. I know the 60' times can improve, and I know improving them will improve my overall times. However between the two runs I listed, track conditions where realitively similar, 60' times were almost identical, same tires, and same car, just the engine was in two different states of tune.

Those cams are supposed to pull really hard on the top end, which would mean a faster trap speed wouldnt it. Wouldnt just a header give you a little bit more on the top end?

 

a/f ratio was right around 13.1:1 before VTEC. Was around 13.5:1 after VTEC and tappered to the richer side as the car revved higher ended at 12.8:1 @ 8600rpm.

The peak hp and tq #s are deceiving: car ended at SAE 178hp and 119tq at 8600rpm. Torque stayed really really flat through the entire run never dropping not even at 8600rpm. (it was a really hot day, correction factor was 1.11)


[Modified by 98 ITR 815, 6:30 PM 10/7/2002]

 

With 170/120 on the stock tires I ran 14.26 @ 98 (at sea level). With 175/125 on slicks I ran 13.87@99. Totally stock I was trapping 93-94. Somethings up .... 900 ft elev. isn't that much of a power robber .......

Check your compression, and check your valves. If they are out of whack, you could be getting enough blow by that you are losing power.

Your 60's should be in the 2.2 range. But 2.3 isn't THAT bad .......