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Discussion Starter #1
I really want to whittle into a high 9 second pass.
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331 with a vortech s trim... had a max of 14.3lbs of boost.. really no slip on the whole datalog.. afr 11.3 to11.5 through the pulls.
The car is on E 85.. so ilept adding timing until mph stayed flat.. then puld the last 1.5 degrees out.

C4.. 3.31 gears on 275 50 15s.. cutting 1.58s hitting it off idle... cant get to launch off the transbrake without blowing the tires off... every time.

Car is at full weight... so do i just start to strip some weight out 1st? I was kinda thinking of trying a taller 275 60 15 bit unsure if that would slow me down.

Also was thinking of spraying like a baby 35hp dry shot??

Open for ideas I'm not thinking of.
 

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I really want to whittle into a high 9 second pass.
Combo
331 with a vortech s trim... had a max of 14.3lbs of boost.. really no slip on the whole datalog.. afr 11.3 to11.5 through the pulls.
The car is on E 85.. so ilept adding timing until mph stayed flat.. then puld the last 1.5 degrees out.

C4.. 3.31 gears on 275 50 15s.. cutting 1.58s hitting it off idle... cant get to launch off the transbrake without blowing the tires off... every time.

Car is at full weight... so do i just start to strip some weight out 1st? I was kinda thinking of trying a taller 275 60 15 bit unsure if that would slow me down.

Also was thinking of spraying like a baby 35hp dry shot??

Open for ideas I'm not thinking of.
We have a mid to high 11 second Foxbody, stock original 302 bottom end, heads, cam, C4 with a brake, 4000 stall converter. For the last year, we were running 275/50/15 Nitto 555 drag radials. We too had traction issues. It would hook approx 1 out of every 3 passes. When it would hook, it would lift the front tires about 6”, and mid to low 1.5s 60’ time. We were getting ready to install a shot of nitrous, and in the process went to a 275/60/15 MT ET Pro drag radials ( so we went from a 26” tire to a 28” tire, and we run a 4.10 gear). We put the new tires on prior to the nitrous, and thought we would give it try on motor with the taller tires, and I too thought it would slow us down. I was pleasantly surprised, the car hooked harder than ever, and ran our best ET ever on motor Which was an 11.61. Just my experience. Since the new tires were installed, we haven’t had any traction issues. The pic below was our 1st run on the 28” tires on motor. We now have a small shot of nitrous, but have only been able to make 1 pass, and it still hooked hard with no spin, running a 11.10, with a 1.47 60’ (launching with a 50hp shot of nitrous).
 

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Hopefully someone who knows drag cars will chime in. Get it to hook and drop the 60. You have the mph to run a very low 10 / high 9.
 

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Discussion Starter #5
Yeah... consensus seem stick a 28 inch tire under there and pull some weight out.
So that's gonna be my focus.
Maybe a hero pass in the fall
 

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What does the car weigh? What is your 60ft now? What does your rear suspension consist of? I would go with the MT 275-60-15 Radial pro's, that's what I run. If you cant hook now more power isin't the answer unless you spray it in 3rd gear.
 

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Discussion Starter #7
Haven't gottwn to scale it. So full weight full interior.
Strange 10 ways se full loose.
1.58 60 foot... it hooks off idle.
Can't get it to hool off the Tbrake.
 

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What stall speed is your converter? Also you said transbrake but no mention of 2 step... If you dont have a 2 step rev limiter you should get one as it sounds like you’re hitting the tires at too high of an rpm on the transbrake. For tires, go with 275/60/15 Radial Pro’s for sure.

Also sounds like you need some suspension adjustments. Its hard to tell without a video to see how much squat you’re getting in the rear. Drag radials don’t like a lot of squat. thats why big time radial race cars separate from the rear tire Instead of squating. On stock style suspension there isnt too much to do to change that. But as a starting point i would tighten up the rear rebound a couple/few clicks and loosen the front rebound by a click or two. The other side to that would be if you already have too much rebound in the rears and its hitting the tire too hard...

Recap: 275/60/15 tires, transbrake with 2 step at a lower rpm, more rebound in the rear shocks. Get a video and lets see what the car is doing.

(there’s also the option of tightening up the rear sway bar if you have an adjustable setup... but make one chane at a time and see how effects the car)
 

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Your optimum et based on trap speed is a 10.01 (Formula is 1320/trap speed so 1320/131.82=10.013)

In this case it means you're going to need more power or less weight. Preferably both in addition to improving that 60ft.
 

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Your optimum et based on trap speed is a 10.01 (Formula is 1320/trap speed so 1320/131.82=10.013)

In this case it means you're going to need more power or less weight. Preferably both in addition to improving that 60ft.
I never understood this equation. If it takes the entire 1320 to reach the trap speed how does it work? It’s not like you come off the line at 132mph and run that constant speed the entire time. Trust me I’d love to believe it! I had a little motor swapped civic with a 75hp shot and it’d trap 101 all day long but it never felt like or beat any legit 12sec cars. Not say the equation is wrong but I feel it leaves some room for embellishment
 

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1320/101= 13.06 and most fwd cars don't 60' well so that would hurt you some.

I would say this is a rule of thumb. My Personal best run beats the formula, but most come up a little short. Often time if a car spins the ET and MPH go up so that's going to help.

Most 10.0x car trap about 135.
 

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At least you get to race. Our track may not open this year at all. Best case scenario is Sept open date. That gives just 3-4 weeks of racing before it is shut down for winter.
 

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A video of it launching would help.

radial cars need a lot of anti squat to hit the tire and then you need to control the separation with the shock to keep it there.

what is your suspension setup? Unless you’re running relocated uppers in the rear, the lower you can get the car the better it should work.

full loose in the suspension is the wrong way to go about it. A single adjustable strange will adjust the extension and if it is full loose then you are letting the car separate too quick and probably unloading the tire just after the hit.
 

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the lower you can get the car the better it should work.
I've never heard this before but have noticed how low many cars do sit. Can you explain this?
 

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As far as tire size and gearing goes; isn't the goal to be at or just above the engine rpm where it makes peak power when you go through the traps?
 

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I've never heard this before but have noticed how low many cars do sit. Can you explain this?
I only know as much as I’ve read and I’ve read things that people much smarter than me have figured out but their explanation of it is,

You want the lower rear control arms as close to level as possible, if not just ever so slightly angled up. You want the rear upper control arm to be angled downwards toward the body side.

Having the control arms setup this way will give you a more ideal instant center and anti squat percentage.

To get the Lowers as close to flat as possible, you have to lower the car. Stock or near stock, the lowers will be pointing up.

Near stock height to around 28” fender height, The only way to get the uppers to slope downwards toward the body is to use Team Z or Baseline relocated uppers.

If you are using NON relocated uppers, the only way to get them angled downwards is to slam the car down BUT then the lowers will be pointed downwards so you will need relocation brackets for the lower control arms.
 

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I've never heard this before but have noticed how low many cars do sit. Can you explain this?

having the lowers pointed up will hit the tire very hard and unless you have the right shocks to control this, you will probably unload the tires right after launching. This is how the SSM lowers work, they let you hit the tire very hard.
 
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