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Discussion Starter #1
I am running Hoosier quick time pro's 27x11.50-15 and just got back from the track yesterday. The best time of the day was [email protected] on 28-29psi. I am still spinning the first part of 1st gear. It seams to hook the second half of 1st gear and then its fine. I was running 15psi cold in the tires. The 60' was around high 1.7's. Just wondering what you guys with similar tires are running for air? I am going back next Wed to better the 60' and am going to try 13psi and see if that helps.

Here are the specs of the car.
93 Sc300
Bl67 .68
Aem
Bl400 4k stall?
TT auto diff
28-29psi.

I left the line around 4,100rpms and 15psi off the foot brake. That was pretty much all I could get it to hold before the car started pushing through the brakes.

Thanks
Lawrence
 

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Inline6Performance
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1,482 Posts
Lower the tire pressure. I usually run 13-13.5 psi and cut 1.4x 60'. Keep lowering the pressure until you hook. If the tires wrinkle while sitting, they are too low and will get sway on the top end.

Mike
 

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1,150+ rwhp club
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rear alignment makes a big deal on these IRS cars. The easiest way is to get a alignment with 200-300# of sand bag in your trunk so it is squatted when getting aligned.
 

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9's Club
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How are you launching your car??? What kind of suspension are y ou running?? If you get a 28" tire you will drop at least .4 of that time just because fo the better top end acceleration from the taller gearing. And a TRD diff is going to save you a lot of wheeling.

But if you continue to run those tires try knocking 1psi out of the tires every pass until it hooks
 

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Discussion Starter #5
rear alignment makes a big deal on these IRS cars. The easiest way is to get a alignment with 200-300# of sand bag in your trunk so it is squatted when getting aligned.
I just aligned it the other day, but didnt add any weight in the trunk. I was trying to get as much positive rear camber as possible. With the car lowered I ended up around -1.5 degree negative camber.

How are you launching your car??? What kind of suspension are y ou running?? If you get a 28" tire you will drop at least .4 of that time just because fo the better top end acceleration from the taller gearing. And a TRD diff is going to save you a lot of wheeling.

But if you continue to run those tires try knocking 1psi out of the tires every pass until it hooks
Rear suspension consists of..
Auto TT diff
Tein HA's ( rear set 4 clicks hard)

I am launching the car off the footbrake and e-brake for now. Just stalling it up and regulating the boost around 14-15psi to not push through the brakes.

Here is the video of the 10.7 pass.

http://www.youtube.com/watch?v=GVqJCkWesHc

The auto is a bit different to drag than the 6-speed was. Still trying to get used to it. Is it possible I need to leave with more power?

Thanks guys for the help.

Lawrence
 

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9's Club
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I just aligned it the other day, but didnt add any weight in the trunk. I was trying to get as much positive rear camber as possible. With the car lowered I ended up around -1.5 degree negative camber.



Rear suspension consists of..
Auto TT diff
Tein HA's ( rear set 4 clicks hard)

I am launching the car off the footbrake and e-brake for now. Just stalling it up and regulating the boost around 14-15psi to not push through the brakes.

Here is the video of the 10.7 pass.

http://www.youtube.com/watch?v=GVqJCkWesHc

The auto is a bit different to drag than the 6-speed was. Still trying to get used to it. Is it possible I need to leave with more power?

Thanks guys for the help.

Lawrence
I have the same car the same tranny :) adding weight is NOT a good idea there is plenty of weight already on that thing!! you need to make your rear suspension as soft as possible for better weight transfer onto the rear tires, do what you are doing now but try 14psi (then 13 and so forth) and you may be able to add some more power off the line. When this tires waste order hoosier 28x10.5x15 full slicks you will thank me for it :) And think about a TRD Diff in your near future, is a safety thing more than anything, i have been wrestiling my car away from the wall for many years now! i finally got mine.
 

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Discussion Starter #7
I have the same car the same tranny :) adding weight is NOT a good idea there is plenty of weight already on that thing!! you need to make your rear suspension as soft as possible for better weight transfer onto the rear tires, do what you are doing now but try 14psi (then 13 and so forth) and you may be able to add some more power off the line. When this tires waste order hoosier 28x10.5x15 full slicks you will thank me for it :) And think about a TRD Diff in your near future, is a safety thing more than anything, i have been wrestiling my car away from the wall for many years now! i finally got mine.
Yeah, I definately plan on running a TRD and maybe a GS400 diff with 3.27 gears in the future because I like to drive my car every other day. I will Try lower air pressure and report back after Wed. I acually have a buddy with a set of 28" hoosier slicks that he said I could borrow. I may try those out after I give these one more try.

Thanks for the help man. I would like one day to get this thing close to where you are so your car Is an Inspiration:bigok:
 

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9's Club
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Yeah, I definately plan on running a TRD and maybe a GS400 diff with 3.27 gears in the future because I like to drive my car every other day. I will Try lower air pressure and report back after Wed. I acually have a buddy with a set of 28" hoosier slicks that he said I could borrow. I may try those out after I give these one more try.

Thanks for the help man. I would like one day to get this thing close to where you are so your car Is an Inspiration:bigok:
Hahaha, your car will be there in no time, DX3 did a lot of nice things to it, so i know you have a solid car, make sure you loosen that back suspension to its softest setting.
 

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EZ2CYI1
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Hahaha, your car will be there in no time, DX3 did a lot of nice things to it, so i know you have a solid car, make sure you loosen that back suspension to its softest setting.
It's my understanding that you want the rear shocks to be set stiffer so as the car transfers weight (from our naturally soft springs) it's pushing the tires down to the pavement harder. I messed with a friend's car (the RSP stock twin car that lost to Anna in the TX2K8 finals) last spring and just from firming up the rear shocks the car hooked a LOT better.

To the OP, do you have the rear sway bar connected still? I have my front and rears disconnected and the car transfers weight like crazy and sticks great on stock suspension on the street with my 67, though I'm not running 28-29 psi like you are. Disconnecting the rear sway made a big difference for me.

Just my two cents from personal experiences.
 

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Discussion Starter #13
It's my understanding that you want the rear shocks to be set stiffer so as the car transfers weight (from our naturally soft springs) it's pushing the tires down to the pavement harder. I messed with a friend's car (the RSP stock twin car that lost to Anna in the TX2K8 finals) last spring and just from firming up the rear shocks the car hooked a LOT better.

To the OP, do you have the rear sway bar connected still? I have my front and rears disconnected and the car transfers weight like crazy and sticks great on stock suspension on the street with my 67, though I'm not running 28-29 psi like you are. Disconnecting the rear sway made a big difference for me.

Just my two cents from personal experiences.
Yeah, sway bar still connected. I may try and disconnect the sway bar next week.
 

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EZ2CYI1
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I don't know if it works as well on an auto car as it does the manual cars, but it's worth it to at least disconnect the end links on the front and back and just see what it does in a parking lot or something.
 

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The Red Beast
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Hey, Lawrench hope u do low 10sec with u SC300. I"m happy if I can run mid 11sec with my 6spd 61mm turbo. good luck and give a update.
 

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9's Club
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It's my understanding that you want the rear shocks to be set stiffer so as the car transfers weight (from our naturally soft springs) it's pushing the tires down to the pavement harder. I messed with a friend's car (the RSP stock twin car that lost to Anna in the TX2K8 finals) last spring and just from firming up the rear shocks the car hooked a LOT better.

To the OP, do you have the rear sway bar connected still? I have my front and rears disconnected and the car transfers weight like crazy and sticks great on stock suspension on the street with my 67, though I'm not running 28-29 psi like you are. Disconnecting the rear sway made a big difference for me.

Just my two cents from personal experiences.
You want the rear of the car soft, this is why the HKS drag's work so well azmmong other things their spring rate is almost ecxact as stock, and they have a very stiff front spring. There is a tech article in mkiv.com that compares all spring rates that gives a great insight in drag suspensions.

As far as the sway bar, it helped my car a lot :) I forgot that one
 

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EZ2CYI1
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You want the rear of the car soft, this is why the HKS drag's work so well azmmong other things their spring rate is almost ecxact as stock, and they have a very stiff front spring. There is a tech article in mkiv.com that compares all spring rates that gives a great insight in drag suspensions.

As far as the sway bar, it helped my car a lot :) I forgot that one
I think we're on the same page. I was talking about having a soft spring rate to let the weight transfer, but a stiff shock to push the tires down as the weight comes back.
 

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You are leaving with too much boost. If you can get 15 psi that easily, then you have a really loose stall and/or too small A/R on the turbo. And if you spend time to "modulate" the boost back to 14-15, you are on the converter too long.

Either modify the launch technique for maybe 10 psi, depending on track conditions, or put a bigger exh housing, which will give you more power to boot!

Al
 

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Discussion Starter #19
The stall is pretty loose and the A/R is definately small (.68). I would imagine my car is not making that much power at 4K and that is where its leaving the line at. It ramps up on boost pretty fast and seams like its starts spinning. I will try and launch the car at 10psi and see if that helps. Thanks for the input.
 
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