The FFR website quotes a 1/4 time of 12.3 for one of their street roadsters, with a 302/348 hp. (298 RWHP), and a 3.55 final drive ratio, with a speed of 113 mph. It seems the SB are able to get the better hole shot, due to the traction issue, but the BB come up with the higher speeds.:o

I ran a 12.91 at 107mph with a 2.0 60 ft. If your car is running an 8.0 in the 1/8 mile your losing power after 660 ft. My car with a 302 runs 8.33@85 in the eighth mile. With a stroker windsor your mph should be higher in the quarter unless your at high elevation. Have you dynoed your motor? All of my pass where on the stock BMW diff and I would let off in second to prevent wheel spin. Good luck the Cobra is a hard car to launch on street tires. I've not tried drag radials.

later

dennis

MDP:
I don't think you're turning that bad a time's for what you have. I'm assuming that's a stroked Windsor. You didn't mention your cam but if the car is light you don't need as much torque. You only (LOL) want to pick up .6 and you are there. You didn't mention how many times you have run the car but I assume, enough that the 12.5 is your benchmark. Unfortunately, increments of improvement from a benchmark are usually measured in .01's and not .1's. Your 60ft's are killing you for sure. I think it's attainable with what you have. If you are serious, some suggestions with limited information on your vehicle would be:

1. (REAR)The rear is too high. 3:50's would definitely make a difference and may be worth a lot. Unless you're motor is high winding; 3:70's will be too low. I don't know where you're shifting. In a BB, shifting at redline usually hurts more than helps. If you have enough ratio to get you through the 1/4 without redlining before the trap; I shift at just over peak of the torque curve; i.e.; my motor flattens out at 7000. My peak torque is around 5700 and the shift light pill is at 6000, which means the shift is completed at 6200 by the time my feeble body reacts.
2. (Tires) Go around the water and definitely do NOT do a burn out. Drag "radials" are radials, so the walls don't wrinkle and they get SLICKER with a burnout. I've been to that show. Clean them off for a couple of seconds. That's ALL. Call the manufacturer and get a warning base line on lowest air pressure. Mark the tire and the rim with 2 white lines touching. Drop the air in increments within their range. First time it slips a little, it should "settle", so don't panic if it moves a tad (tire slipping on the rim). Launch it again after the first line move and see if it "seated" at that spot. It usually does. If it moves again; then go up a couple pounds. It should stay there. That will squeeze as much efficiency out of the tires you own. Suggest you test at home; don't want you losing a bead at 100mph.
3. (Shocks) Have one of your sidekicks watch you launch or film it. You gotta squat for traction (and hold weight transfer to the rear). I went to adjustable coil overs and it made a big difference. The front end never drops with my foot in it, once the weight transfers. Big difference with adjustablity.
4. *(SHORTIES)* BIG time transfusion. Take off the side pipes and buy a set of 12" to 16" shorties. Slip on's, held with a sleeve buckle. DRAMATIC increase in HP, probably worth 60HP to 90HP on mine. The difference in accelleration is shocking and it will help you with a SB on the back end of the track. That being said; Re-JET it with the shorties on it and the air filter off. NO restriction. It's a cheap date and not a big deal for major gain.
5 (Distributor) With MSD; two "light" springs to bring total advance in ASAP.
6. (Shift light) If you don't have one; get one. Their cheap and you can hook them up in 1/2 hour. I used a 6" band and attached it to the steering column. I wired it with a male/female plug "in-line". Makes it portable. You will be consistent and can experiment with shift points by changing pills. You can NOT look at a tree, a tach and launch and THINK and then move your hands and feet with all that **** and be consistent. Not if you're trying to improve times and dial-in track efficiency.

These are all cheap mods, excluding the rear. All of it is cheaper than radical mods to the motor. You mentioned a bottle. Personally; I won't do it to mine. Neat stuff, but nitrous pushes the motor beyond the design limit and things BREAK . It's brutal on the engine. Will it get you there? Probably! I raced all summer and last year too with a street / strip car. I ain't broke nuttin yet. Two reasons I believe. NO BOTTLE and I don't stress my motor. I have a rev pill at 7000 and I haven't touched it yet. BTW: that rev limiter is also brutal on your motor. I live by the shift light.

My Cobra's a porker at 3200lbs wet:

Average 60 fts: 1.6's and best at 1.52
Average 660's: 7.0's
Average 1/4 mile: 11.1's all day. Best ET in 2006: 11.03
Average MPH: 118 to 123mph, contingent on track. Best was 126.

Example of a new tweak. My rear at 3:73, is too low (based on my trans gearing) and I'm out of the "real" power curve 100ft before the trap. My shift light stays on through the trap but I don't hit the limiter. I just bought 28" used drag radials which are 2" taller than my M/T ET's at 26". That will raise my rear ratio a tad. When my rear blows (28 splines) then I'll go to 3:50 gears and 33 spline axles. The 3:50's should put me in the 10.8 et area. Slicks would do it now but I don't feel like leaving the rear at the tree on launch. I'm trying a cheap tweak to slip in there.

IMHO, I think you can get into the 11:00's with the motor and car you have. This game truely requires calculated tweaking and you haven't experimented much yet. I have a goal of the 10's, like you want the 11's but I can't afford a Winston Cup motor either. I started out in the HIGH 11's, but NOTHING on my motor has changed. I got .7 by tweaking. (I didn't mention RT's either. Minor detail.) It's time consuming but making subtle changes DOES make a difference. Have fun with your car and the challenge. Gotta go.

Bernie

Bernie,

One of the best written advice comments on drag racing that I have seen. A big help!

Thanks!

Cheers!
Dave

Here is my drag racing story.

I had a mild 351 that put out 326 RWHP. My rear was a 3.10 (which is the stock BMW E-36 ratio) open rear. I turned 12.3 at 116 mph oh yea I have Nitto drag radials.
I trashed that engine on the track (see my photo's). I replaced it with a Dart block 408 with a forged steel bottom end. I used the heads from my 351 which were AFR 185's, so they may be a bit small for the larger displacement. Any I dyno'd 418 RWHP. I then had a 3.73 limited slip differential assembled by a local shop.
I went back to the strip to break 12 seconds. Well I only got 3 runs in and missed a shift to third twice. But my best run was 12.3 but with a speed of 120.
So I guess the big cubes do give you give you better top speed.
But the good news is the car is a beast on the track. I run with big blocks
427's and 460 without any trouble at all. Maybe if the straights were a mile or so they would pull away but in a half to 3/4 mile straight we are running together. Of course speed out of the corners gives you a bit of an edge on the straights, thank's to the great handling of the Backdraft. BTW I run slicks sometime but mostly run Nitto drag radials on all 4 wheels. They are great RR tires you just need to aid a bit more air to compensate for the soft sidelwalls.

I have the TKO600 which is a bit of a problem. I have the street model with the .68 overdrive. On a long straight away I redline 4th at about 120 and when I shift to 5th the engine almost lugs, or if feels that way. The rev's realy drop. If I had to do it again I would go with the T-56, 6 speed, you get a .86 or so 5 gear and then for road cruse 6 is .68.

Hi Dave:
Thanks for the acknowledgement. It's kind of hard to give meaningful suggestions without knowing the vehicles specs, and I only touched on the tip of the iceberg. You make a lot of adjustments based on the time slips; they're like reading plugs. Carbs, jetting, plugs, manifolds, fuel pressure, fuel, shock dial in, tire pressure, track temp, air density, etc. It's a bottomless pit too, if you really get into it. But some basic stuff gets you into the ball park and then you get into serious tweaking.

As Ernie said; most Cobra's run in the 12.00's and a reasonable percentage will run in the 11.00's with some adjustments. 10 second club is serious. The Cobra problem is predominently "wheel base", followed by suspension. BB or SB doesn't matter. A high winding SB with the right cam, gears and weight can get there just as easily. However, the average Cobra is a 90" wheel base (+or- an ") which is too short to be conducive to stellar weight transfer in a standing start, hot launch. 12" in wheel base makes a HUGE difference. Plus the chassis is low and the transfer tends to push parallel to the deck instead of down on the rear wheels. Path of least resistance is for the tires to spin, instead of bite (unless tubbed with huge rubber). That's why a lot of "mid size" body cars with wheel bases in the 110/115" range are the most efficient at the drags, regardless of whether it's 60's Falcons, Fairlanes, Chevelles, etc. or 2006 body styles. The altered class with a tube chassis have short wheel bases like a Cobra but they set the engine back to compensate and assist the weight transfer. They also see the sky line on launch. We're building a tube chassis 64 Falcon, naturally aspirated 427 powered for "race only" for next year. It will be a 9 second car. Some guys knock the drags VS track but going in that straight line for 440 yds as fast as you can get there, isn't as simplistic as some think. As Ernie noted; the driver factor is in the equation too. There is just as much technicality involved, as in road racing and they are both a hell of a lot of fun. I'm running at Mt. Pocono Speedway next month on a banked oval track which I'm also looking forward too. I just like to go fast, stay within my physical limitations and not kill myself in the process. Anyway; if anyone else is interested in D-strip opinions, don't hesitate to email me if they would like a sounding board. I've made my share of mistakes chippin away at the 10 second club in a Cobra. No point in someone else making them too. I'll get there; hopefully before the snow arrives this year.

Bernie

I took my Cobra to the drags last night, (first time back since high school 23 years ago). On my 3rd run I did 60' 1.94, 1/8 8.3, 1/4 12.9 at 107. Lots of room for improvement, but what a BLAST!

A few years ago, I took mine to the 1/8 mile drags having not dragged since 1969 in HS. I ran almost exactly 8 seconds @ 90 mph. Great fun

I haven't run the 1/4 'that many' times, mostly to verify what the old motor did and a few runs with the new motor to compare. An expert I'm NOT!

One thing that I really enjoyed was that virtually EVERYBODY I ever ran against got the 'hole shot' on me, including near stock FFR's with a 302. Why enjoy THAT? Because I would HUNT THEM DOWN and PUT THEM AWAY before it was over. :LOL:

If you are only trapping 105 mph you either are running out of fuel, don't have enough timing in the car or both. Get the car dyno tuned, check you A/F to see if you are going lean up top. Detonation is hard to hear sometimes with the noise of the motor, but will show up on the graph. 60' isn't bad, gears may result in more spin if you not hooking now. You should be able to knock 1 or 2 tenths off that on drag radials and even more if you throw on some et streets or slicks, every tenth cut in the 60' can be worth 2 at the top.

I agree with Jay, a 408 with 500 hp should be putting up closer to 120 mph trap speed. Belive it or not, your trap speed doesn't change that much with wheel spin and is a very good judge of how much power you are making. You need to get your mtor over to a dyno and see what the true story is. From the way your car is running on the fisrt half of the track vs. the balk half you may just want to get a friend to check and see if you are getting full throttle on the carb.

Justin

Cashburn/jay

Said it all. You have a HP problem at the top end Get to the dyno.

later

dennis

you might not have a hp problem---

A speed problem in the area of 10-20 mph from expected performance can many times be traced to alighnment, dragging brakes, unusual aero drag, slipping clutch, or letting off the gas and early braking

Let some one else drive the car so you can see whats going on with it and get the second opinion

One of my friends pro-stock Camaro( 1980's) had such a screwed up suspension that it ran over 15 mph faster after a set up

Check to see how hard the car rolls by gently pushing it on level ground , straight ahead and in a rt and lt turn

Jerry

11.9 @ 113
Jag independent rear with open diff (for now)
Consistent 1.7s in 60'

SBF stroker that last dyno'd at 352 rwhp. Honestly, I expected more trap speed. I've done several mods since I got the car, dropping my time from 12.6 to the 11.9, but interestingly enough my trap speed has stayed at 113 for damn near every run. All the gains (time and mph) have been in the first 1/8 mile.

I haven't run the 1/4 but in the 1/8 mile I was consistantly turning:
1.7 sec 60'
7.43-7.50 1/8 mi
95-98 MPH

I usually start off with slightly above idle rpm and hit the gears about 4 out of 5 passes. With a clean run I'm in the high 10s to low 11s, 125 mph to 130ish mph with times and speeds relevant to DA of 1500 to 4000 ft.
Here's my set up.

Superformance 2040
Roush 427R-095
3.73 rear end
TKO 600
Mickey Thompson ET street drag radials, actual height 27 inches
Superformance side pipes
set of headers from Olthoff
Pro-Systems carb
large 2 1/2 inch tall oval S & B air filter

I bought a new set of side pipes. I'm excited to put them on the car for testing. I don't know much about exhaust theory and facts, but we'll see how they work on the car.

My Cobra with IRS and a 3.08:1 gear cuts a solid 1.6 sec 60' time every run. Do not try to tell folks that IRS will not hook. I do not run slicks either. My 1.6 sec 60' times are on 275/40-17" Toyo RA1 tires (DOT road race tires).

I think most folks do not have a good enough tire for a launch (still you do not need drag slicks for 11 sec runs), they do not have the power they think (as-installed losses and lack of perfect tune), and they are not used to finessing a high-power car off the line.

I know my comments will make me popular, but as I've said before:

"The cheapest, easiest way to improve your car's ACTUAL (not bench racing) performance is to put on a good set of tires" - Then you have to actually go out to a track...

I have to agree with Itbites with a couple of exceptions. Tires are very often overlooked and are one of the single most important components of any kind of racing. Most of my tickets show high 1s to low 2s 60' times with BFGs. My best time was 12.1 @ 116 with a 60' of 1.845 and that was when my IRS was a 3.47 open diff. Now it is a 3.64 IRS limited slip.

The chassis dyno shows the rear wheel hp and torque around 450. All the above was with a 750 demon that would not hold a consistent tune. I have now built an 850 with several different companies’ parts and now this thing is motorcycle fast. I can not tell you guys how important a good carb is and a major part of that is air bleeds. Make sure you get a center section with "screw-in bleeds" and get your air/fuel between 12.7 and 13.0, all the way through the curve if you want to race for the sake of a little economy.

How do I disagree....drag radial are the best tires to drag with. However, you can narrow that gap with exceptional street tires. My average 60' times are let's say 2 seconds, that's 4/10 slower than Itbites in sixty feet! That's nearly half a second. You can't spend 20% of your time on 5% of the track and expect a decent run. Spinning tires is for show, not for go. The other is the IRS vs. straight. IRS can perform pretty well but with all the uneven loading, wheel hopping and inferior energy transfer they can't compete. Straight axle dominates drag race and IRS dominates road race. I would say this though. IRS can do both road and track better than a straight axle can.

This is a good thread so let's keep it up.

Here's a good run I did last Saturday. I think there's a bit more in there with some jet fiddling.

DA 2100 ft.
10.913 @ 128.759 time slip

The date on the time slip is off by a day. It was 2 December 2006.

Superformance 2040
Roush 427R-095
Olthoff 2" primary headers
Buckshot Racefab side pipes, 3 inch internal
Pro-Systems 1000ish CFM carb
1/2" and 8AN fuel line from tank pick up to carb
Aeromotive fuel filter
Carter mechanical self regulating fuel pump
maid in Taiwan oval Cobra type intake with 2 1/2" inch tall filter
Mickey Thompson ET Street Drag radials, 325/50 15
Detroit Truetrac 3.73 rear end
TKO 600

Greg, Nice times, glad it continued to run faster as the day went on.

Jeffko, Straight axle does dominate drag racing (primarily due to KISS design and ruggedness), but I know of many IRS cars in the 9s, so until we're talking about 9s, I do not think there is the difference in performance (maybe breakage) that is purported. When our cars are running 9s, then we can have the IRS is no good for drags debate...