andyfloyd

Hmm well maybe I'm not hitting 125 when I think I am according to logs then. I'll have to gps speedo it to really know.

Erat

iTrader: (5)

All I really have to go on is gearing calculator. The speedo in my car is not at all accurate and I wouldn't trust it anyway if it was. I do know that the gear calculator is pretty accurate (at least at normal driving speeds). I do not think my tires are standing up at 120mph. Maybe big balloon drag tires, but not R1Rs.

I ran another test but started in 3rd which was stupid because I was half way through the power band at 60mph with my little turbo. This run I started at about 50mph so I had a rolling start through 60. I lost a ton of time with a 1.0s and 1.2s (3-4 and 4-5) shifts. 14.5 seconds 60-125. So it does validate my first time I got, or at least, the time I got from X speed to X speed. Since I don't have anything better to datalog with, this is about the best I can do.

andyfloyd

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The shifts kill the time, just roll out in 5th long pull. Trust me bro

andyfloyd

just for reference

Erat

iTrader: (5)

Super bikes are outrageous.
In fact that entire list makes the ~13s I did in the SS look like a slug.
Ill try and get some data tomorrow morning.

andyfloyd

Start in 5th like I said way before 60. Then when you roll through it you're already in boost. I'm not sure if this list is supposed to be hit the gas at 60 and count from that point, I would lose time waiting on spool. I do a lot of tuning on my car with 5th gear pulls because it gives you really good data, so I literally have like 20 logs to pick from. 7 seconds seems crazy fast but my car isn't slow either. I like this more people need to hop in this

Newaza

Pick up a dragy. They are pretty cheap and VERY accurate. I've tested it at the track and its almost always within a few hundredths of a second and 1/2mph of the timeslip.

andyfloyd

I may do that, they are a little over a 100 bucks so it's not just a oh cool I'll buy it purchase ya know. But I do want one

Newaza

Since its accuracy is proven and its repeatable its a good tuning tool. Pretty cheap for what it can do imo,

sonofthehill

iTrader: (1)

My logs from the dragstrip show 7.6 seconds from calculated 62-125, shifting of course. Both high 11's and low 12's.

andyfloyd

Nice! That's about what I was expecting from your car. I need to get to the drag strip I've been able to keep up with cars that run mid/low 11s and that would back up my 7 second 60-125 time.

Erat

iTrader: (5)

Somehow what I wrote got deleted. Anyway.
Rolling through 3500rpm(60mph) to 7000rpm(125mph). Not sure how much more i'm going to get out of a 2560 at 12psi. I could add boost, but I blow out spark in the higher RPM with the stock coils. And my duty cycle gets spicy with more boost. E85 life. It seems to be at full steam around 3500rpm in 5th.



What do we think? Add more timing? It's at like 15* now. Maybe 17* at this lower boost. This engine is kind of high compression, I don't want to push it.

andyfloyd

So you're running e85 and only 17* timing? Is that a built motor? You could literally be running 22-24* no problem imo. Also why is your spark getting blown out, I run stock nb1 coils at 22psi they are just fine.

Newaza

I run stock coils too and well over 30psi. Close your plug gaps a bit and you should be fine at your boost level. For bigger boost I run solid copper core plug wires, and solid core non-resistor racing plugs gapped at .020ish.

Erat

iTrader: (5)

Naw I run 15* of timing. And yeah it is a built motor. I have a hair dryer 2560 with like 9.5:1 compression. 94 coils blow out at 20psi with a .025 gap.
Edit* this car is kind of built just to thrash. Just rip it at every opportunity. I could do endless 60-125 rips until I ran out of gas if I wanted. So it's tuned rather safe. I'd also be far more confident if I had a knock sensor.

kamel6k

Andy, you have to correct your megasquirt speed with a gps reference. From straight math you usually see 6% diference from true speed versus teorical speed. Than you have tyre diameter diferencees from manufactoring and simple tyre wear. Go to tunerstudio and tweak your tyre diameter until tunerspeed shows GPS speed. Other factor Dragy corrects is slope. It invalidates any run over 1% slope, and bellive me, it's easy to go to a straight you think it's uphill and it's actually downhill.

Regarding beeng faster with using only fifth gear, just do the math of average HP from 3500 to 7000 vs 5500 to 7000, there's no way your faster with single speed run, even adding 0,25s to a shift.

That last table only shows how diferent 400hp are different in different countrys, i have a 400hp miata faster than a 997TT, 18PSI is faster than a veyron with the "same" 400hp.

der_vierte

I was really looking forward to the discussion we are having here. Good points were made.

If anyone has a dragy or driftbox, please let us know and post your setup.

For the guys, who can only take datalogs (including me), we should make 1:1 gear runs from say 2000rpm to fully spool even the laggiest setups and compare from there.
My run posted above was 50mph all the way to redline at 7300rpm in my 1:1 gear and a 4.1 diff.

Please go on guys, I like where this goes

edit:
We should all buy dragys and keep it at 60-125mph

Newaza

I have a dragy and have used it while at the drag strip. The dragy is always very close to the timeslip from the track. However the track I go to is only an 1/8th mile track. I have run a best of 6.88 seconds and 107.88 mph, the dragy said 6.86 seconds @ 108.09mph so was only 2 hundredths of a second and less than 1/2 of a mph difference, so very close. According to dragy i did 40-100mph in 4.15 seconds on that pass. On that pass it also recorded 11.51 seconds @ 75 mph, of course I was slowing down and on the brakes shortly after the 1/8th mile, but the dragy was still recording data. That pass would have been well in the 10's in the 1/4 had I room to run it out and still stop before end of track. I havent set up my dragy to run 100-200kph yet but may next time I go to track, Im just not sure if there is enough room in shut down area. Going by standard calculations for power adder cars of 1/8 mile trap speed x 1.26 (usually at minimum for turbo cars) 107.8 mph in the 1/8th should be roughly 135mph minimum in the 1/4mile so I'll likely have to run up to near the 1000' mark for 125mph. I don't plan on running that fast on the street. You get caught going that fast on the street you will go straight to jail.

sonofthehill

iTrader: (1)

Ok, I measured my wheel radius with a yard stick on my crappy uneven garage floor and it is almost 11". That gives roughly 22" diameter, a bit different from the 23.1" on the calculator. If I use a 43 series tire in the calculator I get 21.9. This works much better, nope I can't do 125 in 5th.

Newaza

Hey Andy I just looked at you head replacement video. On that video you "timed" 60-120 in 5.8 seconds. After watching that I have to agree with kamel6k that you may want to check your logging software speed against a gps. I'm still a firm believer in the dragy data though against most other forms of diy measurements for performance metrics. I've tested the dragy, the g-tech (older version), and the perfexpert app. (its a paid app) while at the track. The dragy was by far consistently the most accurate to timeslips from the track, and yes you would trust the timers at a nhra sanctioned track over other forms of diy timing measurement. Prize money is on the line so it has to be accurate. The dragy is also the only one that I've tested so far that shows road slope. If money is tight The perfexpert app wasn't too terrible. The perfexpert did require a little practice to get the start sensitivity correct for the most accurate results. It also was the least accurate of the three a tried so far. The perfexpert app consistently displayed a higher trap speed by several mph in the 1/8th than track slip. However once you set it up right the 0-60mph measurement was usually within a couple tenths(perfexpert usually displayed 1 to 2 tenths quicker) of the others, so not great but not horrible either considering the price.