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ET slip....opinions?


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#1 _LS1 Taxi_

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Posted 31 January 2016 - 09:27 PM

I'm looking for opinions on what's happening here. High MPH, slow ET.

60' 1.75
330' 5.01
660' 7.81
660mph 87.4
1000' 10.24
ET 12.25
MPH 115.53

Car info
LS1, 4 speed auto
3500 TCT converter
270rwkw
9" LSD 3.5 gears
225/50r15 rear ET radials (24" diameter)

I'm thinking I need to go to a 26" rear tyre (235/60r15) and hoping that alone will get me into the 11's.

Thoughts?

#2 SA EH

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Posted 31 January 2016 - 09:37 PM

Bomber would say you need a descent engine like a 202 to get into the 11s.... So just thought I'd beat him to it.

#3 _LS2 Hatch_

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Posted 31 January 2016 - 09:41 PM

I have those tyres here you can give a go.
However, what revs and gear are you crossing the line?
I went backwards when I put these tyres on.
I was crossing the line in fourth just under the limiter, then I put the taller tyre on and was crossing the line in fourth at about 5500, limiter is 6800

I am of the understanding that you want to be at the top end of your revs in fourth gear, so the tyres MAY not be the best to go taller.
I ran my quickest time of 12.08 on a 24" tyre. Lost nearly a second going taller. I am actually quicker on my street tyres as they are 25" tall.

Now I have gone from 4:11 gears to 4:33 the tyres may be better suited, but I'm still thinking that I need 25" sticky tyres to be optimum.


These are only my thoughts and should be used for fuel for thought, not as gospel.
Cheers

By the way, there's no need for you to go any quicker until I get into the 11's and make sure you can't catch me ;)

#4 wot179

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Posted 31 January 2016 - 09:41 PM

3.5s are ruining your ET.

It will be worse if you go to a 26.

I recon you need to go to a 26 with 4.11s.

It could be the way you are shifting, too.

#5 Ice

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Posted 31 January 2016 - 10:21 PM

Asked my racing buddy he said ditch the 3.5 s Daz
3.9s or 4.11 as above

#6 _LS2 Hatch_

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Posted 01 February 2016 - 07:06 AM

If it's diff gears as noted above, and you don't want to change them, tyre size (diameter) can play the same part and change the ratio for you

 

http://www.advanced-...ators/TireSize/

 

The calculator above will allow you to play around with different ratios.

By my calculations

225/50/15 is 23.86 inches rolling diameter

235/60/15 is 26.10 inches rolling diameter

at 6000rpm and 110mph with 225/50 your diff ratio would be 3.87

at 6000rpm and 110mph with 235/60 your diff ratio would be 4.23

 

so changing the tyre size works the same as changing doff ratio

so if you stop creating power at6500, and you cross the line at 6500 at 110mph you would need a diff ratio of 4.59 with 26.1 inch tyres

 

Thats my 5 cents.

time to actually do some work :)



#7 ido09s

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Posted 01 February 2016 - 07:29 AM

I have to say I reckon your et and mph are pretty much bang on.

 

Albeit with an SR20 Nissan 200SX, I used to run a 13.0/13.2@107mph so to run a 12.2@115mph I think is quite reasonable.....

 

Spare a thought for me, on average I run an 11.5 at a consistent 138mph ;) The only thing that's better than top ending 10 second cars with a mid 11 second car would be a decent 60 footer (ie under 2.0) and a low 10 second time slip :(



#8 _COSH_

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Posted 01 February 2016 - 08:27 AM

I agree with the above, MPH is on the money, get the 60' time down below 1.6.

 

I used to race a VX Calais LS1 with the same RWKW as yours.  I ran similar numbers until I changed the diff gears from 3.46 to 3.91; then the 60' times dropped and I was in the 11's.

 

Are you getting any wheelspin off the line?  That would be the only reason I'd move up to a larger diameter tyre.



#9 LXCHEV

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Posted 01 February 2016 - 08:35 AM

Agree with the above, your 60 foot and MPH are both good (easily good enough for 11's as they sit). Those numbers are actually quite close to my car back when it was at its peak - 60 foots anywhere from 1.62 to 1.69, and 114MPH, but I only had 245rwkw, and that saw me running 11.77's pass after pass with perfect traction. My stall is a 3200 with 3.7's.

Without knowing how it's revving over the finish line, sounds like your gearing is not ideal.

If you can pull another half tenth off your 60 foot time, you'll really be in the zone too (it'd be good to see you go a 1.70 flat).

Traction, tyre choice, and diff gearing... The 11 is hiding in there somewhere!

Just to add to the overall discussion, I've also heard a general rule of thumb in the drag world that a tenth off the 60 foot time can net as much as 3 tenths off the overall E.T.

#10 ido09s

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Posted 01 February 2016 - 08:53 AM

I don't know about 3/10's, but 2/10's is probably more on the money.

 

If I could run a 1.5 60 footer, which with 500rwkw it should do, it would make me a very happy man ;) From a low 11 with a 2.0 60 footer to a who knows with a 1.5 would be a vast improvement ;)



#11 _Bomber Watson_

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Posted 01 February 2016 - 09:02 AM

Bomber would say you need a descent engine like a 202 to get into the 11s.... So just thought I'd beat him to it.


Yes! My army is coming together slowly.

Advice above sounds on point, definitely don't go taller tyres, and be careful with shorter tyres, less sidewall will make it break traction quicker in general.

#12 Redslur

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Posted 01 February 2016 - 11:19 AM

26" ET radials and 3.9 gears and 11's it should be Daz.  Speaking from experience here mate :-)



#13 LC-GTR-1969

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Posted 01 February 2016 - 11:21 AM

The strange thing is, that going shorter in the gearing is no guarantee that it will run faster- in this case it probably will run quicker ETs with 3.9s but just for point of conversation, when I reduced my tyre size (effectively making shorter gearing), I lost ET even though I gained better 60 foots from the better off the line pick up. Basically it will depend on a few things.

 

I think though (from my limited experience), that most cars will get from point A to point B quicker with shorter gearing, unless the shorter gearing is just not suited to the setup (ie might make you need an extra shift (in a manual) and still not put the car in peak power rpm range, as I experienced). A lot of guys round here will know much more than me though.

 

Also, the MPH looks good for 11s, based on my observations at the track. If you can drop the 60 down to 1.6 with your current setup you may get close to a 12 flat, but I dont think it will get you into 11s unless you try some gearing changes to see how they affect pickup- with a 3.9 or 4.11 I think you will be well into the 11s, like 11.7 or 11.8 with a 1.6 60'.



#14 ido09s

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Posted 01 February 2016 - 12:02 PM

in order to go quicker, its going to need to go faster as well..... I wouldn't have thought that 115mph would be enough to get it into the 11's???

 

some of these may come in handy for people on here

 

wallaceracing.com/calculators.htm


Edited by ido09s, 01 February 2016 - 12:08 PM.


#15 _COSH_

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Posted 01 February 2016 - 12:20 PM

in order to go quicker, its going to need to go faster as well..... I wouldn't have thought that 115mph would be enough to get it into the 11's???

 

some of these may come in handy for people on here

 

wallaceracing.com/calculators.htm

It's fast enough, just needs a better launch.  

 

I was running 11.8 @ 115, but the 60' was 1.65. 



#16 ido09s

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Posted 01 February 2016 - 12:28 PM

wow, ok. I need to get my engine into something lighter and more suited!!!! I would be over the moon running an 11@ only 115mph!!!!



#17 _COSH_

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Posted 01 February 2016 - 12:34 PM

wow, ok. I need to get my engine into something lighter and more suited!!!! I would be over the moon running an 11@ only 115mph!!!!

That was in a full weight VX Calais too, 1600 odd kg.  Mid size cam, Short gearing and a 4200 converter helped.



#18 ido09s

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Posted 01 February 2016 - 12:40 PM

Apart from drag radials what am I doing wrong!!!!

 

Manual, 1400kgs and 500rwkw and I cant get it to 60 foot. runs low 11's@138mph all day :(



#19 _COSH_

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Posted 01 February 2016 - 12:50 PM

An Auto gearbox.

 

To run good times with a manual, you need full slicks, or at least drag radials, and 5000+ rpm clutch dumps! 



#20 ido09s

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Posted 01 February 2016 - 01:02 PM

I wish. I cant justify pulling the manual out given the box and clutch owes me almost $8000

 

I have drag radials (255/50/16's ET's) and an engine that will cop 9500rpm all day AND a 2 step :( damn thing wont run an et though will it!!!! don't know what wrong with it. It doesn't blow the tyres off it on launch, it just wont 60 foot. Gets minimal wheel spin but just top ends everything I race. Can give a 12 second car almost 100 metres head start and by the finish line I round him up like its standing still

 

sorry to the op for hi jacking the thread :(


Edited by ido09s, 01 February 2016 - 01:03 PM.


#21 _COSH_

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Posted 01 February 2016 - 01:15 PM

I wish. I cant justify pulling the manual out given the box and clutch owes me almost $8000

 

I have drag radials (255/50/16's ET's) and an engine that will cop 9500rpm all day AND a 2 step :( damn thing wont run an et though will it!!!! don't know what wrong with it. It doesn't blow the tyres off it on launch, it just wont 60 foot. Gets minimal wheel spin but just top ends everything I race. Can give a 12 second car almost 100 metres head start and by the finish line I round him up like its standing still

 

sorry to the op for hi jacking the thread :(

I take it it's got a large turbo that takes a while to spool?  I had a mate that used to race his A70 supra, had the same issue, shitloads of power but couldn't get it off the line.  He swapped the manual for an auto and built up the boost on the line and ran alot faster.  Try building up the boost and slipping the clutch using the handbrake.  Trial and error and you should get there.

 

Or just use NOS to spool it up :D  



#22 ido09s

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Posted 01 February 2016 - 01:28 PM

Its an RB26 with a Precision 6766 on it. Its responsive as to be honest, its got a decent head on it. For some reason I think there is something wrong with the setup though. It doesn't blow the tyres off it like most cars do. I can clutch it in 3rd on the street (i.e. rolling at 80kph and give it 9000rpm and side step the clutch) and it doesn't turn the tyres, it squats and takes off. Its great that it does, but it leaves me wondering why as similar cars can turn the rears at will. I run 265/18 Advan Neova AD08R's which aren't that stupidly sticky on the street, but they are good

 

its got plenty of boost as its got a 2 step on it. I probably need to figure out how to adjust it though. Its got about 8psi and 7000rpm in it at the moment which doesn't seem too bad, but I don't know how to change it. Tuner doesn't seem to be at the track when I have time to race and vice versa which sucks



#23 LC-GTR-1969

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Posted 01 February 2016 - 02:06 PM

Turbos are a different kettle of fish to N/A.  When I last raced a gemini turbo, we 60 footed the same, I was quicker to 1/8 track, he started catching me and passed just before the line, ETs very similar, but he had 8 more mph. Took some time for turbo to spool I imagine... good setup would offsett this I imagine



#24 Redslur

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Posted 01 February 2016 - 06:20 PM

I was running 11.9 ETs @ as low as 110MPH last year in my LX 355. That was with 1.7 60ft times. 115MPH is good for mid 11's in a well set up lightish car. I ran 11.3 @119.5MPH with a best 1.6 60 foot time as a comparsion. It all comes down to trial and error and of course your car set up.  Knowing Daz has a similar sort of power to my LX, It should run high 11's with a 26 inch tyre and 3.9 gears.



#25 gtrboyy

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Posted 01 February 2016 - 06:40 PM

As it is now with small tyres definately has a high 11 sec time in it.Stay with smaller tyres.

 

Good 60 foot says reasonable traction high mph says mid 11 capable BUT that would require significant changes you wont like.

 

 

I'd wonder if gear changes in 4l60e need tweaking or there's slippage in auto/convertor.

 

 

 

Few guys have cracked 11 in heavier less rwkw vy-z commodores with only standard engine/valve springs,5000rpm stally,3.9-4.11 gears & slicks...crude but works.






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