Brain Twister

Here`s one for the brain surgeons, Why? if a 2250 lb. car is sitting on the starting line Not moving yet, goes to the 1/8 mile and is going 207. mph from a dead stop. why is it only picking up 50 more mph when it gets to the 1/4 mile mark from a 207 mph flying start? i know thats the way it is but why? it don`t make sense. some one give me a reason so i can figuer out a way to beat it. come on Drazy, is it the jerk, the twist or the watusi, Gene Sr.

[ February 18, 2005, 05:27 PM: Message edited by: ttutubono ]

 

Increased leverage in lower gears and parasitic drag.

 

I personally don't think they have enough camshaft and enough gear. Think about it. Most are using the same camshaft when the roots blower was being used. I'm not sure what rear gear they were using, but I think the most common is 4:30's. How about a 4:10 or 3:90 gear?

 

Maynard and Alkyguy, I think your both on to something, I looked up that 3 dollar drag word,( parasitic)and found that the aero gets worst and worst the faster you go, and the cam thing got me to thinking of how back before we had gear drives, we used a simple timing chain, now after a few runs the chain would stretch and retard your ing. timing and your cam timing, so you bump up the ing. timing and this is what i`m thinking now, the cam timing would stay close to what it was untill the motor got to the top end and then it would retard, and the car would mph more, this i know because i could never run the mph i did afterr i changed over to the gear drive, so to over come the drag, we need more power from the 1/8 mile to the 1/4 mark,dose any one make a variablele retard gear drive?? so what do you think? gene Sr.

[ February 20, 2005, 10:45 PM: Message edited by: ttutubono ]

 

Gene wasnt there a device called a " Cam a Go " to change timing during a run? was hooked up to a morse cable. From what I recall this was in the seventies and was then outlawed.

as far as the Newtonian physics of acceleration past half track the best description that even came close I found at Momentum work and energy

[ February 19, 2005, 12:23 PM: Message edited by: Woodchip ]

 

gene,i dont usually get into these conversations,but in reading your posts, you seem to be a sharp person,so this is my 2cents worth.i must agree that gear reduction does increase torque,and also wind resistance at 230+mph makes that slick body seem like a brick wall.the bottom line is [in my opinion]hp=mph.the more power wou make the faster the car will go.also,i don,t know the other gents that posted,but my guess is that if they are on something,it,s speed,the speed i am refuring to is et&mph.also,i read your post about[the perfect engine]and i have some questions,email me your phone number,as i would like to pick your brain about fuelsystem for psi blower.motormant@netscape.net

 

When running an engine on the dyno, with a belt drive timing system (jesel,whoever). Have any of you guys ever watched the cam gear with a timing light when the engine comes under load?

[ February 19, 2005, 01:04 PM: Message edited by: rpmhiperf ]

 

In my opinion this is a drag racing question not limited to TAFC. If you look at the numbers, fuel funny cars have the same approximate speed increase the last half (50mph). Fuel dragsters are relatively close (60mph). They have much more power than we do, no gear reduction, a lot more clutch, and a lot more drag but the increase in speed is about the same. That should eliminate horsepower, torque, and aero, so WHY?
I think that it is just impossible to significantly increase the speed of a vehicle that weighs that much (who knows how much it weighs at that speed with the aero effects) more than 50 mph in less than 2 seconds. I guess the answer is like my parents used to tell me when they could't come up with a good answer: "It's because"

 

I think that "induced" drag (down force) increases dramatically throughout the run. That induced drag coupled with a rapidly rising "parasitic" drag is what is slowing the rate of acceleration per foot. The cars accelerate hardest only when these two separate drags are lowest.

[ February 19, 2005, 11:32 PM: Message edited by: Maynard ]

 

barry h said,more power_no gear reduction_a lot more clutch_a lot more drag,let,s think about this, more power=more speed,like 255mph vs 325mph.no gear reduction=not needed due to [more power]a lot more clutch=due to more power,a lot more drag,kind of like that slick body going threw 2 brick walls at 320mph.back to gene,s question[how to make the car go faster from quarter track to finishline]1-change that 2250lb car into a 180 gram bullit.or 2-cut wind resistance.i think barry h,s parents had it right-just because. anybody know how to cut wind resistance?

 

Mike you can`t cut wind resistance, nhra won`t let you. but the timing light that rpmhiperf said on the gear got me to thinking, how about a riffle drilled cam shaft, like Drazy`s distributor and oil pump drive, if that shaft is only driving the oil pump and mag, and deflecting, imagine what that cam is doing under the load of 1.000 lb.spring pressure. ( not sure if it`s all the springss @16,000 lb`s, or if some negate the others)but i`m sure that cam is twisting like that oil pump drive,( come on guys keep that brain going) we can fix this, (drag racers can fix anything but a broken heart) Gene Terenzio Sr.

[ February 20, 2005, 11:09 AM: Message edited by: ttutubono ]

 

To help cut down on cam shaft twist what about a belt driven oil pump? I know the reliabilty of the belt would be an issue (breakage, belt comming off)etc. The Pro Stock guys run a belt driven vacum pump and oil pump, I think on the latter of the two and it doesn't seem to be an issue for them. I know car weight, hp, torque & class etc. affects all of this but like you said drag racers can fix anything but a broken heart.

 

maybe some one needs to put a sensor of the front and rear of the cam and watch for twist to see how much and where it occurs

I believe the cars slow after 1/8 mile mark because all the torque multiplication has run out
clutch, gear changes, tire growth and all that is left is pure horsepower to accelerate the car from that point

 

Gene is correct about all of the torsional twisting going on with the cam however, I don't agree with the 16,000# thing due to the fact that for every valve that is opening, another is closing. Given that, I dont believe that a closing valve is exerting the same pressure as an opening one especially at high rpm. At rpm, I dont believe the lifter associated with the closing valve is in any real stable contact with the back of the lobe. Rather, I believe it may be bouncing down the backside of the lobe. Certainly, the valve is bouncing on the seat regardless of spring pressure, albeit more controlled with heavier springs.

I dont have any idea how you could eliminate torsional flex in a cam short of throwing it away and going to some type of electric or hydrolic valve operating/valve event timing process. I given alot of thought to this type of system and also the idea of using a different type of valve. The valves we use today, never get out of their own way. No matter how far you open em, they still route (restrict) flow out of the port and around the valve's face. I believe that a simple sliding door sliding forward and exposing the chamber to the port would increase flow dramatically to a point of even reducing the size of the port needed to make today's horsepower ratings. Obviously, the exhaust configuration would have to be modified to same extent as in bringing the gases straight up and out of the head. But that would be the easy part.

In addition, given that today's limitations to making horsepower is all flow related, with this type of valve, I believe that the amount of potential horsepower on a given motor would then be based on limitations of fuel provided at the chamber and limitations of what a lower end could possibly withstand for a couple of seconds.

But no matter, even if we did develope this, its against the rules.

 

Maynard , how about putting another gear drive on the back of the motor, insulated from the clutch? if it was posabule do you think the extra weight would be offset enough by the extra power?, and if there is any extra power! Gene Terenzio Sr.

 

i have always wanted to build a supercharged
2 stroke motor
no valves
but of course we know this would never get an approval

 

John if you could build a 500 cu.in. 2 stroke you wouldent need a blower, but maybe in ihra they would let it pass? Gene Terenzio Sr.P/S GREAT idea

 

Gene, at "first blush" one would suspect that an additional timing gear would help to stabilize the cam. However, if one were to consider that the crank itself is subjected to flex and twist arguably worse then the cam is subjected to, the notion of a secondary timing gear acting as a stabilizing platform would soon evaporate. I would almost believe that this second coupling could/would aggravate the problem. If you could run a hydrolic pump from the front of the cam and turn a small motor at the rear of the cam, then yes you could stabilize the cam somewhat I suppose.

Another factor to consider beside the errant valve event caused by torsional flex is the push rods "noodleing". Little has been done to eliminate this flex entirely. Despite the cam grinder's best effort to make a valve do what we want, when we want, it is still far from accurate.

 

Maynard ,You don`t think riffle drilling the cam would relive some of the deflection? Gene Sr.

[ February 20, 2005, 04:21 PM: Message edited by: ttutubono ]