Help me out with my ET

[lukecp]

I got a G-tech for Christmas today, and went out and made a run with it.

The run was a 15.66@91.9 mph and the 0-60 was 7.19 seconds.

I couldn't make any more runs due to traffic....really suprised me how many people were out on a 2-lane road in the middle of nowhere on Christmas day.....

A little slower than what i expected, but not too bad for a 4200 pound (with me in it) truck that has 3.07 gears.

Now, isn't the mph a little high for the ET? I would like to have more like a 15.0-15.3 1/4 mile ET, and i think my truck is capable of that. I did spin for about 15-20 feet off the line, even with 275/60 tires and the highway gears. I shifted at about 5200 rpm.
I was barley into 3rd gear when the 1/4 mile was over.

My engine combo is a .060" over 350, about 9.7:1 compression, pocket ported 186 fuelie heads with 2.02/1.60 valves, 204/214, .420/.443 cam (bascially an old-shcool RV grind), 1-5/8" headers, 2-1/2" true duals with Flowmasters, Performer intake, stock HEI, and a 1406 carb jetted about 6% rich. My tranny is a completely stock TH350.

Any suggestions for a low 15-second ET would be appreciated

[bow-tie-bandit]

1. Lower the tailgate
2. Take all the winter weight out of the bed.

Just kidding

Go to your local track and go for it, its safer and probably more accurate. Merry x-mas

[dinnut]

try the tailgate thing... maybe put some weight for traction in the back. you need the weight to transfer the rear of the truck to get good traction and better times.try not to spin the tires if at all possible

[dinnut]

http://www.prestage.com/Car+Math/ET+...t/default.aspx

remember that from the engien forum? assuming 15.66 at 4200 pounds it says youre making 216 horsepower so your et should drop a bunch

lets say your engine make 300 hp which is probably close--- you should run a 14.
try the tailgate down better aerodynamics. the 3.73 youre gonna get one day will probably help that number out a BUNCH anyway

ru running premium gas?

[Class of 69]

Luke, the 3:07's are whats killing the ET and giving the high MPH. You have plenty of engine. You just need to wait for the 3:73 posi, and the times will down into the high 14 sec range.

[cableguy0]

i agree the 3.07's are killing you just wait till you get the 3.73 to even worry about it.

[68racer]

The G-Tech will give a higher mph as it shows actual speed. The mph at a track is averaged over the last 100 feet(?) and is always slightly slower than your actual speed across the line. This is because you are still accelerating.

The best way to hook up is slicks, but you'll have to get to the track!

[cableguy0]

slicks in a close to stock truck arent going to do anything but breaks parts such as ujoints rears trannys. they arent needed. when he put the 3.73's in the truck it wont spin near as much because the lower gears will plant the tires better

[lukecp]

I know 3.73's would help out tremendously....but the truck is my daily driver much more than a hot rod, and i drive on the highway most of the time so i need to keep the 3.07's right now. Plus i just put in anohter 3.07 rear, lol.

3.73's with posi will come with time...just awaiting funds for an OD tranny, so it will be awhile.
I suppose i could take all the junk and tools out of my bed and try again....then play with the timing and carb jettings a little bit...
I'm just kinda looking for close to free help, lol.

Thanks!

[cableguy0]

take your timing to about 40 degrees total and see what happens. i bet it will get ya a tenth or two

[cableguy0]

also if you figure up how long its going to take you to make up the gas cost with the od tranny and 3.73's the od tranny wont look so great an alternative. plus that th350 is stronger than a 700r4

[lukecp]

Yeah, i know it will take a long time for the OD tranny to make up for the gas cost. That is why i'm not in too big of a hurry to do it, lol.
My TH350/3.07 works for now, and i am happy with the performance....but there is always room for improvement
I would mainly like the OD tranny so i could comfortalby run 3.73's on the highway....right now my truck can comfortable cruise 75mph at 3,000 rpm's....with the 3.73's i would be only going about 65mph at that rpm. With 3.73's and OD i would be going around 100mph at that rpm
I've been dreaming about a built 200R4 latley....i wouldn't mind a TCI unit, but they cost $1300 (!).

Well....if i have 216 hp at the rear wheels, assuming 20% drivetrain loss that puts me at ~270 at the flywheel....now, is that the old style gross HP, or the real HP my engine is putting out?
If so....270 net HP is pretty good...same as a Vortec 5.3.

[cableguy0]

that number would be your real horsepower because it was measured with the truck driving and all accesories bolted on. the old numbers were taken with no accesories at all on the motor

[lukecp]

Sweet then....so that would proably give me 300+ old school HP at the flywheel.....of course the real net HP is what really matters...gross is just for bragging rights

Thanks again!

[cableguy0]

your combo is probably making right around 3 would make a bit more with a holley

[Stroker]

yellow72custom using a virtual engine calculator freeware
http://www.virtualengine2000.com/DynoOverview.htm
and your 91mph and 4200lbs data ,Horsepower is calculated to be 297 HP, very much in line with your estimates. With good traction and ideal gearing and converter you sould be able to run about a 14.8 1/4. These calculations are probably just a little high because of the way the G-tech calculates your speed as pointed out by 68racer. If your going to stick with the turbo350 and 3.08 gears for awhile a little looser converter 2,400rpm and some sticker tires would help the et out. Maybe someone has one of the drag calculators and could see how much.

[dinnut]

according to the virtual engine calculator on the link stroker provided ( i dl'ed the free program). to run 100 mph in the 1/4 in a 4200# car 394 horses are required?

a 300 horse 4200# car could run a 14.76 in 1/4 mile

[Stroker]

yellow72custom, have you had a chance to gather any braking data? It would be great to have a data base of different brake configuration performance. Factory drums, factory disks, aftermarket upgrades, ect.....

[djracer]

Sticky tires would definately help! You might try removing your air cleaner and shifting at a little higher rpm. I have a similar motor with a holley and a small convertor and I have been 14.31 at the track with a 3.07 gear. My 3.73's and posi should be done any day!

[dinnut]

Originally posted by djracer
Sticky tires would definately help! You might try removing your air cleaner and shifting at a little higher rpm. I have a similar motor with a holley and a small convertor and I have been 14.31 at the track with a 3.07 gear. My 3.73's and posi should be done any day!

of course your truck is going to run faster... its a shortbed. his is a longbed good suggestions tho

[68racer]

slicks in a close to stock truck arent going to do anything but breaks parts such as ujoints rears trannys. they arent needed. when he put the 3.73's in the truck it wont spin near as much because the lower gears will plant the tires better

If the truck is not capable of the extra loading of a pair of slicks it's probably best not to be taking it to the track at all. They are one of the most cost effective additions I ever made.

All other factors being equal (i.e. no posi fitted) the deeper (3.73) gears will produce greater mechanical advantage and are therefore more likely to create wheelspin.

How does gearing plant tires? Suspension and load tranfer does this.

3.73's are a good way to lower ET, the posi will greatly reduce wheelspin.

Try bolting ballast in the bed, tractor weights are good! The increase in weight is more than offset by the better launch. Cheap too!

[lukecp]

Originally posted by Stroker
yellow72custom, have you had a chance to gather any braking data? It would be great to have a data base of different brake configuration performance. Factory drums, factory disks, aftermarket upgrades, ect.....

Yeah, sure i could get some braking distances (factrory disc/drum setup). I bet the distances won't be that great though...i need to adjust the rear drums and i haven't gotten around to it yet, lol.

A 14.8 1/4 would be pretty cool.....can't wait for 3.73's. Too bad it will be awhile though.

I'm going out of town for a couple days right now...when i get back i will start to play with it a little more