Throttle position sensor

[azgearhed]

What kind / type of tps works well with carburetors? I have a Racepak v300 logger and dominator with mechanical linkage.

[manta22]

I think most TPS are simply variable potentiometers with +5V on one end, ground on the other and the wiper arm is the throttle position output. Probably a basic sensor will be some generic manufacturer.

Regards, Neil  Tucson, AZ

[Stainless1]

You may want to use a generic linear sensor rather than a rotational sensor, depends on what you can get mounted on your setup.  Anything that varies with throttle or linkage position will work to feed your data system.

[Milwaukee Midget]

Go to the Holley catalog - I'd bet their Pro Jection throttle position sensor would be an easy adapt, if it didn't bolt right on.

[kiwi belly tank]

Why are you wanting to record throttle position with a carb other than just WOT?
  Sid.

[entropy]

Racepak String Potentiometer TPS Sensor
http://www.hrpworld.com/store/default/instruments/racepak-data-systems/racepak-gps-based-data-system-expansion-sensors-and-cables/racepak-string-potentiometer-tps-sensor-and-vnet-module/show/all.html

It's expensive but it seems to be exactly what you are looking for.

[Sumner]

Why are you wanting to record throttle position with a carb other than just WOT?
  Sid.

We ran one with the mech. fuel injection with the roots blower and now with the C & S blow thru carb.  It has shown in the past how much throttle we can run in 1st and 2nd before finally going WOT in third.  It was way less than the driver thought.  With that info we have gone to taller 1st and 2nd gears.  We also have the data of throttle opening vs. boost levels.  One of the main benefits is seeing the throttle position vs. the air/fuel ratio.  I'm not to concerned about leaner at part throttle settings vs. WOT.  Without the TPS and just the air/fuel data we wouldn't know near as much if the jetting was right or not.

Of course the bad thing is seeing how little WOT you might be running vs. what you felt you ran  .

We have run them a couple different ways.  Off the end of the bellcrank was the best as it was the most linear.  Now we have it a couple feet ahead of the motor on a backet with a cable going back to the carb and it isn't as linear but still like the data from it.  I'm thinking the one we are using now is from a Dodge as it was about the cheapest one the parts house had.  I should know as I bought a new one last summer.  I probably have the box out in the shop if anyone is interested and the car is here if anyone wants a picture.



Above is my last run last summer.  The orange bottom line is the manifold pressure, the blue is TPS and the top red is rpm.  We data logged 16 items, but I just showed 3 of them above.  To the left is the end of second gear, then third and finally part of 4th to the right.  You can see the shift points and the vertical lines at the right and left give the values at those lines.

Notice at the left at 71% throttle it is making 7 1/2 lbs of boost.  We could see that we couldn't really regulate the boost much once in the throttle.  It was nothing or 7-8 lbs and the tires would break loose.  The wastegates had 8 lb. springs.  From that info we now have about 2 lb. springs and will use the wastegate controller for more when we can in up to 6 increments.  That should help the car accelerate better.  Note this was a license run so no major effort to go fast, just get it done.  All of the runs had very little WOT due to the fact they were all license runs.

On the right you can see the car was running between 210 mph and 217 mph for the last 1 1/2 miles at right at 50% throttle and actually under vacuum most of that time.  At the right vertical line the car is at 46% throttle and -2 lbs. of vacuum with a speed of 210.

You can view the chart better if you like in another window here....

http://purplesagetradingpost.com/sumner/bvillecar/A%20license-2013-1.jpg

I'd strongly suggest data logging throttle position if you are data logging at all,

Sum

[entropy]

Sumner
great info, and you just tipped me over the top on running manifold pressure. 
TPS is a given.

BTW: looks like you are running Innovate Logging system?
If so, you have good grounds, very clean traces.  kudos to you.
Karl

[Sumner]

....BTW: looks like you are running Innovate Logging system?
If so, you have good grounds, very clean traces.  kudos to you.
Karl

Yes it is all Innovate and was purchased from a land speed guy, Jerry at DIYAutotune.

I spent more time with it than in the past trying to work on better connections and so forth, especially the way the grounds were handled with the two LMA-3's using a separate terminal strip located above each.  I hope to have a lot of the data logging info up on my site eventually.  I also hooked it all up on the bench and tested all of the sensors and data logged them that way before going into the car.  That helped a lot vs. doing it piece by piece in the car.

In addition we run a separate smaller wet cell battery for all the data logging and the wastegate controller.  We do have the MSD box next to the data logging and even though it didn't appear to be a problem I'd like to move them further apart.  The separate battery eliminates any of the data logging dropping out during low voltage when the motor is cranking over,

Sum

[azgearhed]

Why are you wanting to record throttle position with a carb other than just WOT?
  Sid.

We want to compare throttle position in each gear from run to run-and we have three drivers. Wide open throttle is not an option in second and third gear with the hp we are making.

[azgearhed]

Thanks for the info Sum-I'll be digesting it for a while

[Stainless1]

Wide open throttle is not an option in second and third gear with the hp we are making.

I think I just figured out our problem with the lakester... we are not making enough horsepower....

we have the throttle to the stop about 5 seconds after letting the clutch out and let off after the chute pops...

[SPARKY]

    sounds like you guys have it about geared about right

[kiwi belly tank]

Why are you wanting to record throttle position with a carb other than just WOT?
  Sid.

We want to compare throttle position in each gear from run to run-and we have three drivers. Wide open throttle is not an option in second and third gear with the hp we are making.

Ok, the difference between multipul drivers makes sence. Hooking up the power with out traction control is a seat of the pants thing that I'm sure you know is different on every run.
I've seen a lot of smart people on the salt over the years unwilling to take some power out to get it to go faster. If you can't use it, lose it!
My backyard approach to a three position throttle stop in the past was using three Q-jet idle solenoids & three toggle switches in a row & a spring on the end of the throttle cable so lead-foot-louie didn't crush the thing.
  Sid.
 

[Dean Los Angeles]

It's pretty clear for the high HP and boosted motors that killing power in the lower gears will make it easier to accelerate.

http://www.youtube.com/watch?v=qx_7fFQbV1Q
Here is an example of a stupid fast car. Black Salt racing with in-car camera and data didn't really start to accelerate until the two mile mark. Ok, so that's 275 mph, but . . .

Still hit about 387, but not how you want to manage your run.

Only 64 in first gear, spinning the tires when boost hit. 6 seconds.
Second gear accelerating out of boost from 64 to 94. Boost kicks in at 6,000 rpm and spins the tires for a few seconds and at 111 shift to third. 8 seconds. 1/4 mile mark.
Third gear from 111 to 164. Spins the tires twice. 8 seconds. 5/8 mile shifts into fourth.
In fourth at 4,000 rpm. 10 seconds to gain 30 mph. Next 30 mph in 6 seconds. Next 30 in 5 seconds. Next 30 in 4 seconds. Can you tell when the boost kicks in?
Still pulling strong when the rev limiter kicked in at the 4 1/2.
Still stupid fast.
Holds the C/BFMS record at 364. Another universe faster than anyone else. When they get over 400, and they will, it will have to be with better acceleration in the first two miles.
Acceleration in the lower gears without traction control either needs a throttle stop, variable boost or something that will allow smooth acceleration.