ET in relation to MPH

[Stock Josh]

Im not sure if this should be here or in track talk.

I dont necessarily have one question, but wish to start a discussion per say. The topic is ET in realtion to MPH. For the sake of the discussion it is pertaining to AWD cars only. I see certain cars that ET 12.5 at 107 mph. Great ET for the mph. 60 foot of 1.8 to 1.7. Then there is my car. High 1.8 short times, but an ET of 12.5's @ 112. This MPH is "high", so to speak, for the ET. What I'm getting at is, what have you found that effects this in YOUR situations, and what did you do to counter it. I'm hoping some of you experienced this and found certain factors were leading to the high mph but poor ET. I realize the short time is a factor, and I feel that 1.7's should be closer to what I should aim for. The car has trouble hooking up due to huge weight transfer off the front tires. Im thinking I could hole shot a tenth or so harder if I can eliminate the weight transfer. But I feel I would still be missing 3 tenths. Ive eliminated lag between shifts, the car had a poor tune and used to lag between shifts, and would run 12.9's at 112. But at this point Im somewhat stumped.
Thanks for any input.

Josh

 

[hyboost]

hey don't fell bad i've ran12.1 @ 127.8 with 1.8 60 ft
i scratch my head all the time

 

[Black95GSX]

Shift harder/faster..... "drive it like you stole it".. and be prepared to break stuff.


I went from 13.2 at 107 to 12.7 at 107 just by forgetting to take my foot off the gas when I was shifting..... (rev limiter is your friend).....

I know wheel spin can also be a large part of it...
I ran a 12.09 at 119.22....... that should of been 11's easily. Furthermore that was with a 1.8 60'

My problem was traction... I had none in first and second gear.. that track sucked something horrid for traction...

 

[GRNDSM]

Lets put 60’ times aside as it is pretty clear. .1 sec improvement in the 60’ time will give you .2-.3 in the ¼ mile ET, while making almost no difference in the trap speed (actually, if anything, poor launch increases you trap speed).

Then, it comes down to speed of your gear shifts. Fast gearshifts are EVERYTHING when it comes to making good ET’s. I have seen many drivers disappointed with their ET’s because they ether couldn’t shift fast (lack of skill) or their tranny didn’t allow them to shift fast (mechanical issue). Oftentimes you can get a known good driver to driver to drive your car to see where your problem lays. I often perform such service in the area for the local drivers .

Lifting and not lifting is not all that important in smaller turbos (14b, 16G or even 20G). But with larger turbos you can not afford to lift the throttle (no matter how fast your actual gearshift actually is). Your turbo slows down too much and then takes a lot of time build up the boost back to where it was before you closed the throttle.

When I was using a huge T3/T4 60-1 Stage 5 Garret, I could not lift the throttle. No matter how fast I shifted, as long as I was lifting the throttle, my runs were in the 11.7-12.0 @ 121-123 range. That made me look as an incompetent driver . Re-adjusting my driving style to not lifting gave me 11.4-11.5 @ 121-123 with otherwise the same gear shifts. This still was not perfect, but as good as I could do on that huge turbo with out N20.

For comparison, prior to installing this turbo, I was using a 20G, I was able to several passes in the 11.3-11.4 range at 121-122mph with lifting (and just a fast gear sifts).

My point is lifting (or not) is not as important on a small turbo as long as you can still shift fast.

Leon
RR

 

[Stock Josh]

What about weight transfer? I have a lot of weight transfer when changing gears. Has anyone changed their car for less weight transfer an noticed it improving ET? Im thinking of the inertia being used to lift the car instead of drive it foward with every gear change. Considerable. I have 3/4 inch drop springs. Not anything aggressive. I scratch my head wondering if this is an issue. Or overall torque curve. I still have stock 90 cams, and I shift the 1-2 at like 7800 (TMO ECU, cant seem to shift any earlier out of first), 2-3 at 7000, and 3-4 at 7500.
My 1/8th mile is really poor. 8.0's at about 89-90. MPH is good, but 8th ET is down.
Others who have high mph but poor ( when compared to mph ) ET. What do feel contributes?

Josh

 

[GalantVR41062]

shift faster, but dont break things or miss because it sucks, I ran a 13.4@100 with out lifting in my Galant, 16psi pump gas "Knock" of 45 or so 8deg timing, 85deg out and at rock falls raceway in Wisconsin which is not a good track it is said by many racers to produce almost 1/2sec slower times then other tracks(thats what I have heard hope to see if thats true next year) then with my brothers tranny, bad syncros a best of 13.0@104 a little better boost less knock still on pump gas 20psi. Shift Shift Shift. Try no lift if your tranny will shift at 7500RPM and thats where you should shift to get the engine more twards the power band in the next gear unless your car looses a lot of power its your choice, whats your set up?? mine was stock week motor, mutt 1, fmic, walbro255, afc, act 2100 6 puck, jun flywheel, 3"turbo back exaust. Good luck and dont break.

 

[KRAZYKOREAN]

Josh,

I no exactly what your talking about with the shifting dude. When I first ran my car with my current setup I was getting 12.9-12.8@108 mph. I saw all kinds of peole yielding better times with the same mph and I was like WTF I did have stock suspension at the time and spinning in first and getting squirly in second was an issue. It comes down to what GRNDSM said basically. Even though I do have a relatively small turbo (big16g) it would still loose spool in between shifts when i lifted. My tranny is very delicate and I didnt want to "no lift shift" as I was scared Id brake something. I could get consistent high 1.7-low 1.8 60fts with stock (blown front struts which didnt help weight transfer ) and stock bald tires. I since returned to the track after getting some sportline and agx's (stiffening the crap out of the rear ) with the same driving style (little bit colder ~75*) and yielded mush better times with just the suspension as my mods since the last visit. I was consistent in high 1.7 60ft's, but i was now getting 12.5-12.6@110 ( colder out less knock ) with the exact setup except with some stiffer suspension. This really helped my 60ft's and also my 1-2 shift felt much more solid and got less weight transfer between every shift. Im actually getting a new motor in 3 days and will return (even colder now =)) and will try to "no lift shift" to see if my tranny can take it. With all things equal except new motor Ill be shooting for 12.3-12.4.


Austin (friend of KRAZY KOREAN...aka "candela" on tuners)

 

[TSi92]

Originally posted by Stock Josh
What about weight transfer? I have a lot of weight transfer when changing gears. Has anyone changed their car for less weight transfer an noticed it improving ET? Im thinking of the inertia being used to lift the car instead of drive it foward with every gear change. Considerable. I have 3/4 inch drop springs. Not anything aggressive. I scratch my head wondering if this is an issue. Or overall torque curve. I still have stock 90 cams, and I shift the 1-2 at like 7800 (TMO ECU, cant seem to shift any earlier out of first), 2-3 at 7000, and 3-4 at 7500.
My 1/8th mile is really poor. 8.0's at about 89-90. MPH is good, but 8th ET is down.
Others who have high mph but poor ( when compared to mph ) ET. What do feel contributes?

Josh

You have TMO ECU. You should be able to shift with the pedal to the floor with no fears. When I shift with the stutterbox sometimes I look at the boost gauge in between shifts and the boost won't go past 10 psi from a 14 psi setting. You can feel the hard jerk when the car catches the next gear because the turbo is still spooled up. My ex's car I used to run 12.7's@105-106 mph with 1.7-1.8 60 foots. Shifting fast has a lot to do with quick et's. Think about the ammount of time the car is in zero acceleration in between shifts. I wish I had a way to measure the ammount of time I spend with the clutch on the floor. I bet that going through 4 gears your car is about 1 full sec in "neutral".

 

[T6Rocket]

Sounds like you need drag radials or green dots! Replace the struts if they are old. It is not only what you gain in 60', you gain in the 330' also with better traction. Some weight transfer is okay, but not with worn struts!

Not sure which turbo you are running, but 7500 3-4 shift is too high. It should be 7000 like the 2-3 shift. That is where some extra MPH is coming from - esp the 1/8 mile MPH. Shift lower and you should gain a little ET.

Al

 

[chrisAWD]

it all comes with practice. I'm a little disappointed with my cars 100mph trap average(stock 14b, ic,injectors), but after a little while got my best et of 13.32 on a 98 mph run. this was lifting between shifts, and a low 1.7 short time(i don't remember it exactly and i don't have the slip on me)

 

[Stock Josh]

A little reflection. My car has now ran a best of 11.7 at 119. A couple months ago it was running 12.2 - 12.0 at 118. The 11.7 was with a 1.81 sixty foot. What was the difference? The launch. I was cutting 1.8's when running 12.0's as well, but the car would come out sideways, the tires were loose, and then the 1-2 gear change was difficult. I've found, that when the car leaves straight, and the tires aren't spinning, its MUCH easier to nail a smooth 1-2 gear change, which dropped my 330 time by a ton. All the suspension is the same, and it still weight transfers like crazy, but that didnt seem to matter. And I began shifting at a lower rpm. I shift the car at 6500 now. It still has stock cams. I'm actually in 4th about 100 feet before the 1/8th. Then I just load it against 4th gear for half the track, and run through the traps at about 7000. Now, it appears what I need to address is 60 foot times. If I could cut 1.6's, the car would run a .50 . My best sixty to date is a 1.77, so thats my next target.

Stock Josh

 

[Bohrn]

Josh, how the hell do you go thru the trap at 7grand in 4th!!!???

 

[Laser0385]

The launch for FWD is key. Bad launch: 15.016 @ 101.32 MPH.

Jake

 

[DV8tion]

I also run a stock engine. My car 60fts like crazy and somehow I was lucky enough to get a tranny that shifts like crazy. I have never granny shifted my car at the track, but I am sure it would not run well at all.(TSO4) I have stg 3 TMO. I cannot say enough about 2 steps and 60ft times. My car makes ~5psi sitting still.
I have noticed that an open face helmet helps my ETs by about a tenth. I guess my Full face helmet mutes out too much information i.e. sound and peripheral vision. Just something to think about.

Back to the topick. Here are my two best passes.

60 FT 1.66 1.68
330FT 4.99 4.87
1/8ET 7.65 7.51
1/8MPH 91.94 92.67
1000ET 9.94 9.81
1/4 ET 11.86 11.80
1/4MPH 117.95 111.11

The first pass was 23psi, second pass was 26psi w/spark blow out at ~5000RPM so I had to coast through at ~1/2 throttle. This pass sounded like shit popping and blowing black smoke etc. So basically the car hauled ass to 111MPH then would do no more.