ET and MPH

that hp chart an the calculators on TCI's website dont jive. On Fletchers he says the numbers listed are "net" hp and you X's by .85 to get required rearwheel hp. When you do that I believe the #'s are very low. I think the #'s in the chart are rearwheel hp already and that would jive with TCI's BUT I could be wrong!

The Moroso Power Speed Calculator shows that if a car is setup right and working, 11.35 seconds is indeed possible at 116mph (using the limited info we are given.) To get that would require getting all the available HP to the ground,which isn't always an easy task. If it was, my 121mph would give me a 10.9 ET.

11.70 would be 112mph.

These calculations typically are just averages, and it is indeed possible to run them or even a lower ET at a give MPH.


Do you know the weight of your car?

I am with 347lx. According to my times/speeds/weights the numbers in the chart are a little low. My rear wheel dyno numbers were about the same as the chart. But maybe I'm just not a very good driver

a old carb guy and drag racer told to tune the car mph. change the jets and if mph goes up you are heading the right way and keep jeting up until mph drop then go back to the last get size -1 or 2 and you have it set up

Originally Posted by radracing

a old carb guy and drag racer told to tune the car mph. change the jets and if mph goes up you are heading the right way and keep jeting up until mph drop then go back to the last get size -1 or 2 and you have it set up

That is exactly what my machinist (and drag racing neighbor) told me.

ET is an indication of how well a vehicle's horsepower gets transmitted to the ground.

We are running a 3000 rpm converter, but it seems to be higher than that with this bigger motor, a C4 with the typical mods,3.73 final ratio,the car is an 86 Mustang coupe that was a 4 cylinder car. I don't know the weight of the car. Its a 410 Windsor with C9 heads & solid roller cam.
We will be running it again Friday afternoon. We just got it back together
after bending a valve in number 4 cylinder last Friday. We are not 100% sure why that happened.

Originally Posted by n2omike

The mph tells you how much horsepower you are putting down, and the ET tells you how well that horsepower is getting used.

Fast mph, slow et... inefficient car.

Slow mph, quick et... efficient car.

You'd get more helpful data by posting the mph numbers... if you have any.

Amen...... quick times over mph. First to the line gets paided..MPH is for bragging in the pits.
Get the car to 60 foot.. that one 60' was a tenth faster (1.669)than them all and your 330' (4.80) was the fastest. Looks like you lifted. that was a mid 11 pass happening.
http://crayonmedia.com/wayne/Windsor_Forum/TIMES.pdf

You can chase jets all day, Use to do it and it was a pain. Buy a clamp on pyrometer and make a pass with the meter on max temp lock. The temp number is easy to remember for pefect jetting...How long is the 1/4 mile ...1320 feet. Well that is the same temp number for a gas engine with perfect jetting. Once your jetted to get that number then it's one jet richer on a cold day and one jet lower on a hot day. Or, make the first pass of the day with the pyrometer attached, jet accordingly and the second pass you dialed in... not the 10th pass.. and it's easy piezy..

Jeff

Originally Posted by MCCUTCHEON4

We are running a 3000 rpm converter, but it seems to be higher than that with this bigger motor, a C4 with the typical mods,3.73 final ratio,the car is an 86 Mustang coupe that was a 4 cylinder car. I don't know the weight of the car. Its a 410 Windsor with C9 heads & solid roller cam.
We will be running it again Friday afternoon. We just got it back together
after bending a valve in number 4 cylinder last Friday. We are not 100% sure why that happened.

Well, from the MPH at the 660' mark, I'd say you are off at least .3 at that point and maybe losing more down track. You're about 1000 RPM short on the stall for a better ET and 60'. But I see from the other thread that it's a little late.

Originally Posted by JN-Motorsports

Amen...... quick times over mph. First to the line gets paided..MPH is for bragging in the pits.
Get the car to 60 foot.. that one 60' was a tenth faster (1.669)than them all and your 330' (4.80) was the fastest. Looks like you lifted. that was a mid 11 pass happening.
http://crayonmedia.com/wayne/Windsor_Forum/TIMES.pdf

You can chase jets all day, Use to do it and it was a pain. Buy a clamp on pyrometer and make a pass with the meter on max temp lock. The temp number is easy to remember for pefect jetting...How long is the 1/4 mile ...1320 feet. Well that is the same temp number for a gas engine with perfect jetting. Once your jetted to get that number then it's one jet richer on a cold day and one jet lower on a hot day. Or, make the first pass of the day with the pyrometer attached, jet accordingly and the second pass you dialed in... not the 10th pass.. and it's easy piezy..

Jeff

Thanks Jeff, Good suggestions. I have two nice SW pyrometers that are
the type that have the sender mounted in weld on bungs. They do not have the max temp lock however. I do not want to be guessing at the mixture,
so this sounds like a reasonable fix for that issue. 1320!

Originally Posted by MCCUTCHEON4

Thanks Jeff, Good suggestions. I have two nice SW pyrometers that are
the type that have the sender mounted in weld on bungs. They do not have the max temp lock however. I do not want to be guessing at the mixture,
so this sounds like a reasonable fix for that issue. 1320!

Greg, the temp number is actually 1300 to 1350 for a gas engine using a pyrometer.. 1320 degrees works great for my 408 cleveland and is around 12.5 A/F and it's easy to remember.

Jeff