ET Vs MPH

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69valiant21

69valiant21

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So, Im starting to see a lot of time slips in the mid to low 14s running 95-100mph. Ive even heard high 14s around 100 MPH. Compared to my time slips last year I run 13.80s at about the same MPH, 97ish. I know ET is made in the 60' but the difference just seems odd to me. I dont recall my 60' times unfortunately.

Ill try to post some slips when I get the chance.
 
The difference between low ETs with high MPH and high ETs with high MPH is iether gearing (starting out below the power band of the engine) or traction
 
69valiant21 said:
So, Im starting to see a lot of time slips in the mid to low 14s running 95-100mph. Ive even heard high 14s around 100 MPH. Compared to my time slips last year I run 13.80s at about the same MPH, 97ish. I know ET is made in the 60' but the difference just seems odd to me. I dont recall my 60' times unfortunately.

Ill try to post some slips when I get the chance.
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The guys running 14s at that mph are likely spinning off the line.
 
Years ago, when I was a Mopar pup, my car was finishing at 95 MPH. My Mopar friends were telling me that I needed to change gears and get some slicks. I borrowed a set of slicks from one of them and my et improved just by getting a better hook up off the line. I then went to the expense of getting taller gears.
 
DFX 340 Duster said:
Years ago, when I was a Mopar pup, my car was finishing at 95 MPH. My Mopar friends were telling me that I needed to change gears and get some slicks. I borrowed a set of slicks from one of them and my et improved just by getting a better hook up off the line. I then went to the expense of getting taller gears.
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I'm running 3.91 gear and MT drag radials. I hook up pretty good.
 
Time vs MPH is two different animals, but they will run hand in hand..... sort of. My 318 ran 14.95 at 95 mph. Why does it make sense? I have 2.76 gears, factory stock stall, and full weight car. And..... and.... with my home ported heads and a little more cam, I moved my RPM range up a little. I also lowered the factory "already" low compression by using thicker head gaskets than the factory ones (another low end killer). This makes "better mph vs E.T.".

Example, for instance, 3.91's with a 9.5 converter would drastically drop the E.T., but only move the MPH up a little. I bet it would drop a second off the E.T., but only add about 2-3 mph. So now I'd have a 13.9 car but only 98 mph. In this illustration, I made the car alot quicker, but didn't add 1 horsepower.
 
Drag racers say that MPH is an indicator of HP, ET is The result of how efficiently you use it. (torque converter, gears, and chassis) Obviously HP gains make you faster, but to get the most out of your MPH you need a good set up...

My car when I first got it running had
Best of 13.80 @ 103.7ish

Changed from 2200 stall to 3000 stall
Best of 13.21 @ 103.7ish

Changed to adjustable shocks and 4:10's
Best of 12.99@ 103.7ish

Overall I Gained 8/10 without touching the engine or tune at all... mph unchanged.

I'm hoping to add some power this yr now that the chassis is sorted, and see what gains I have now...
 
I ran my old '71 340 Cuda s/strip car with 3.55's, 3500stall, 8x26" slicks and ran 13.3's@101 I then added around 65hp to the motor, + a 4200 stall, 4.30's/10x28's and went 12.4's@108 almost 1 sec faster but only 8mph more in speed. Basically the longer you spend on the track time wise with slower 60's the longer in effect the track is giving you more time to build speed. Cover the distance quicker with a better chassis and the track becomes shorter effectively and you have less time to build speed, HP/weight is speed, your chassis is your 60ft/ET. Once you've been doing it for a while you'll get to know what a good ET/mph is, and then you watch some stockers going down the track, then it all gets thrown out the window as they will ET real good and mph will be weak because their 60fts are real quick, example of that is say a bracket car with a good chassis will go say 9.85 at around 135+, a stocker with wheels way in the air may run that at 132....we won't get into throttle stop cars, thats another story....just my 2C's.
 
joeboy said:
Drag racers say that MPH is an indicator of HP, ET is The result of how efficiently you use it. (torque converter, gears, and chassis) Obviously HP gains make you faster, but to get the most out of your MPH you need a good set up...

My car when I first got it running had
Best of 13.80 @ 103.7ish

Changed from 2200 stall to 3000 stall
Best of 13.21 @ 103.7ish

Changed to adjustable shocks and 4:10's
Best of 12.99@ 103.7ish

Overall I Gained 8/10 without touching the engine or tune at all... mph unchanged.

I'm hoping to add some power this yr now that the chassis is sorted, and see what gains I have now...
Click to expand...


NICE! That's how you get it done.
 
yellow rose said:
NICE! That's how you get it done.
Click to expand...

Thanks! I'm really happy with it! It's funny, I bracket raced a bunch in my early 20's and was always obsessed with making power to get quicker. I never went to far past "if it hooks you're good"...
I'm amazed with what taking time matching and dialing in my set-up has done.
 
Another big deal is selecting gearage to trap at an rpm that has let your engine put down all that it's got. As in;if your engine powerpeaks at 5500, there's no sense in gearing it to trap at 4400; you have not taken advantage of all that pulling power from 4400 to say 5800 or 5900 depending on the shape of your power curve.You have given up average power during the run.
This is different from selecting a gear to help your car 60ft well.You need both.
With a stick-car,this usually means a 12 or 13 to one starter gear, all four gears, and 4.56s to 4.10s at the other end, depending on your combo. This is where a 3.09 low gear in the tranny can be a big help. 3.09x4.30=13.29; and 4.30s are good for 112=6000rpm, very nice for a 230ish cam in a 360.



My factory stock Swinger 340 with a 4 gear and 3.55s and the factory 268* cam,went [email protected] back in 1971, trapping in fourth at about 4600.

My 68 Barracuda (350 pounds heavier) with a 360 with a 4gear and 3.55s, and a 270* cam, went [email protected], back in 2002 or so,trapping in third @ 6500.

In both cases I had the wrong starter gear;3.55x2.66=9.44. And in both cases I had the wrong trap-gear;3.55x1.39=4.93. And in both cases I only ran 3 gears.

In the 340 case; the mph says I had about 254hp, and the ET translates to about 198hp. The 254hp says I should have ETd at about 13.3. I lost about 1.1 seconds in the suspension,tires, and wrong gearing,etc.

In the 360 case; the mph says I had about 338hp, and the ET translates to about 303hp. The 338 hp says I should have ET'd at about 12.3. I lost about .6 second in the suspension, tires, and running waaay past the power-peak.

My latest combo ran 93 in the 1/8th.
Mr Wallace translates that to 118 in the qtr, and with SS suspension that might be 430 hp and might be 11.3 seconds. Adding time for my crappy street suspension, this might be 11.8 to 12.1 say. The street suspension is staying; I could care less about ET.
 
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Here's some to scrutinize.
The group of three where I was car 27x, it was starving on the top end.
The two together where I was car 6, one was my second quickest run. The other was a wash.
The crumpled one was my quickest so far.

What can you tell by these slips, especially the 105 mph one, and what do you think the car should run?
410ci stroker, COMP XE285HL, 28" tires with 3.23s, Turbo Action "Tight 10" converter. TCI Street Fighter trans. Espo +1" springs and Monroe shocks.
All these runs were letting the trans shift itself. I know the 60ft times are not impressive, I was trying different things off the line trying to get a good launch.
Not out to hijack the thread, just trying to understand how I can run such similar times at such different miles per hour, and thought it might be an interesting case study for you guys.

20170401_075333.jpg


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20170421_202436-1.jpg
 
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A car that runs 105 with a good chassis should run around 12.8, virtually impossible to decipher what happened on those runs with tyre spin and being in auto mode. Get some drag tyres on there get them hot, get some grip and shift it manually at or just above max engine hp/rpm which is probably around 5500? with your motor/cam..and keep it up there till it traps, if that means trapping in 2nd at say 6000 so be it, shift again and you'll hurt the run.
 
I always want to know the MPH. To me, MPH is how much potential for a certain ET there is within a car. ET is how well the owner/driver can live up to that potential. 100mph means with effort and properly matched components and a tuned chassis you should be in the 12s. How deep is a result of how well it sticks.
 
here is my first combo, 66 barracuda, 2840lbs, 440, 600" lift solid, home ported heads, 12-1 trw's, 850 dp holley, tm7 intake, 8" convertor, manual shift 727, 3.55 dana, ladder bars, 14x32 slicks. i bracket raced this to the tune of 11.70et at 121mph. won alot of races with the thing. the mph has a correct et of 10.90. this was the perfect set up for bracket racing where the et and mph are so for off the competition doesn't have a clue.
 
Thats cool bOb, I bet the quicker dials thought they would run you down easy:thumbsup:, but you had 7mph in the bag, so how did you slow it down from the 10.0's it was capable of running it through
 
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He had 3.55 gears and 14 x 32 slicks....probably did not 60 ft very well....
 
Yeah I get that but thats not gonna get rid of 12mph and 1.6 secs in ET from what that car is capable of...with an estimated 550hp@2840lbs, perhaps bOb can enlighten us?
 
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This thread is really making me jones to go try again!!
I really think this car has mid 12's in it if I can learn to drive it. After all the waiting in the lanes, I get excited and forget stuff, lol...I need to slow down and concentrate on building a good routine.
I would like to put a detent in my shifter to lock out neutral and reverse, or get another shifter, but that costs too much right now. Afraid I'll nudge it one too far.
 
KnuckleDuster said:
This thread is really making me jones to go try again!!
I really think this car has mid 12's in it if I can learn to drive it. After all the waiting in the lanes, I get excited and forget stuff, lol...I need to slow down and concentrate on building a good routine.
I would like to put a detent in my shifter to lock out neutral and reverse, or get another shifter, but that costs too much right now. Afraid I'll nudge it one too far.
Click to expand...
I'll be out there next Friday, look for me.
 
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