thanx
jtfx6552 said:Cars were very similar, only difference was the gearing, and the 4.10's were slower. Comparing the ETs then and comparing with the ETs "on the list" now, The results were the same, there were just less differences to obscure that fact.
AT BG, track prep was outstanding, still the 4.10 cars could not compete.
An 03/04 with driver weighs in at 3800 lbs plus, staticly, much less than half that weight on the rear wheels. As you know friction depends on the "normal" force. Even if the 03/04 transfers enough weight to lift the front wheels, and given the moment arm on stock sized tires is about 1 foot, what coefficient of friction will you need to hook up 5000 lb ft?, looks like 1.31. Now that is with 3.55's! Now with 4.10's the numbers grow to 5774 lb ft and a cf of 1.51. On a super prepped track with slicks front wheels in the air, maybe. On a car with "stock" suspension with weight on the front wheels...sounds like spinning to me. For comparison, it looks like you 99 routinely held about 1.38-1.46 (300 lb ft at the engine, 15.26:1 reduction 3300-3500 lbs total weight). Of course, in actuality with all cars on launch, there is the added smack of the inertia of the rotating engine and flywheel. VHT is a racers friend...
Agreed
Agreed, the issue is traction and what it takes to get it. First you need to transfer weight so whatever tires you have in the back can get the grip to transfer even more weight, Since my car is a street car that I like to be able to go around turns and over bumps, transfer and hence traction are limited. For a purpose built 1/4 mile car, I'm sure the suspension can be tweaked to take advantage of the extra T in 1st.
I have heard numbers that high talked about ($800 does seem more typical), the pumkin needs to come out they say, so it is pricier than on a straight axle.
You implied I had never taken a car and upped the gears. While I learned form others mistakes and haven't done it on my '03, I have done it in the past. The theoretical results were the car would be faster, in actual racing it wasn't.
Agreed, however, the auto '03 I was in launched hard on 3.55's since the convertor gives some multilplication.
Since the ability to translate rotaional force into movement depends on the normal force and friction, the distribution of weight and "tightness" of the suspension is critical. If the weight from the front can't be transferred to the rear then the required cf goes through the roof, i.e. trying to move 3800 lbs with only 1750 on the rear axle is a recipe for tire smoke.
I know a few who shift their T-56's as fast as they can be shifted, so I know it isn't that. The lack of transfer does hurt, though, because quick shifts, especially the 1-2 can really break loose the tires, I have seen ET drags, ET streets and BFG dr's all go up in smoke on a good shift.
Once you do those mods, then the car is no longer the typical '03/'04 Cobra. I am sure more gear won't hurt in that situation. It is ashame we will never know how much, exactly it helped. What do you think just the ratio change will take off your ET?
I like to drive my car to the track, which means DR's in the rear, normal sized wheels and radials up front, non drag shocks and springs. Even on the best prepped tracks, the car is traction limited.
Thanks, I did. I hope you did, too.
JT
projekZERO said:theres an old man out here that has a white cobra coupe dynoed 420 hp and 420 tq.
yet he managed a 11.5 @ 116 mph. hows that for e.t. vs. mph and his cobra is stock weight this is off a 1.6 60 ft.
Oh by the way. he has 4.10's
enough said.
jtfx6552 said:Ok, how about me, 11.41 with 441 rwhp, stock gears. Enough said.
2003Slobra said:I have seen enough from the track point of view, but for someone who just wants to SOTP feel on the street, would 3.90's be just about right. I will still go to the track, but not enough for me to worry about if I am going to be running out of room in 4th or not. Other than that the information is great! :banana:
jtfx6552 said:Ok, how about me, 11.41 with 441 rwhp, stock gears. Enough said.
projekZERO said:you ran a 11.4 @ 122.98 mph thats 6.5 mph faster but u didnt mention that
and cecil dragway is 320 ft alt
he did this at fontana 1,100 feet alt.
not to mention u pa guys usualy have better da then us west coast guys.
so 700 ft less alt
21 more hp
and 6.5 mph faster
and all you could do was 1 tenth quicker?
you just furthered my point!
11secCobra said:i went 11.11 on 445rwhp and 4.10s. enough said :thumbsup:
Bob Cosby said:Or me. 11.43 with 355 rwhp, 4.56 gears. Is that enough said?
jtfx6552 said:I have already said that I agree 100% the n/a Cobras need a very steep gear...
projekZERO said:chip. intake. cat back. pulley, thats it.
no midpipe. no port work. no throttle body
projekZERO said:the gears dont hold your mph back.
its in my opinion the gears gears drop your e.t by .2 and change your mph marginaly if not at all.
u cant compare one car and one driver to another.
u need to compare 1 car with same curcumstances. before and after a gear change.
projekZERO said:yes gears will leave u with less traction.
that just means you need to adjust to the change.
projekZERO said:this guy trapped 119.8 mph at a track with a alt of 200 ft. with the 410's. but the prep was poor at only manages a 11.8
so near 120 mph with 420 rwhp downt sound to me liek the gears are keeping his mph down.
projekZERO said:dont forget us socal guys dont have fast tracks like you guys have. and the da makes it even worse.
my local track is 2710 ft. and in the summer da can be around 6000.
try pullin some mph with that!
Bob Cosby said:JT...the majority of the facts you present are accurate and indisputable. Also, I agree that if a car is traction-limited, lower gearing can have a detrimental affect.
~*"Optimal gearing" for the 1/4 mile typically means that you gear the car to run several hundred rpm above peak HP at the end of the run in 4th gear.
Again - this assumes traction. If you race on street tires or are otherwise traction-limited, then you may or may not go quicker with an optimum power gear.
~
Bob