Chassis Dyno- eye opening!

[Drew Pojedinec]

This thread just makes me want to buy a chasis dyno.....

[plovett]

Yes, chassis dynos usually bring up more questions than they answer.  I do think they have some value, but the numbers generated are far less accurate and far less precise than the numbers generated on engine dynos.

JMO,

paulie

[Faron]

I know not everybody can or wants to run at a drag strip , but those numbers mean way more to me than any dyno sheet , be it engine or chassis , bragging papers I call them , Time slips don't lie , IMHO

[Drew Pojedinec]

I agree.  My focus has always been on street cars, where the real details are in how good it runs from idle to 4500rpms, so a dyno doesn't really mean as much.

I wish my local drag strip hadn't closed down (again).  It was a lil 1/8 mile strip about 6 miles from my house.  Made it nice to go off and mess around for a Friday evening.  There is another track an hour away, but that prevents the spotaneous 8pm "hey lets go to the track"

[Faron]

Agree , Ive tuned ( had to ) many big numbered dyno ( engine dyno ) that ran like crap on the street and at the track , the you don't drive a Dyno has more truth to it than is given credit :-) Dynos are great for trying and comparing different combos in an already proved combo , but outright not always the same

[fekbmax]

I'm with you guys on the drag strip deal, (although i still ha vent got my latest combo on the track, getten close though) chassis dyno's are a good ball park tool i guess but it seems like the same car on 5 different dynos gets 5 different results.  Especially those portable trailer mounted deals like the guy sometimes brings up to the truck stop on Saturday nights. At least i didn't have ta pay but who knows how far off that thing is and which way .

[Joe-JDC]

If, and IF a dyno test is actually done with accuracy and everything is adjusted to get the best torque and horsepower reading, IT WILL prove itself on the track.  It all comes down to the operators and if they maximized the combination on the dyno.  That means every combination of headers, intakes, spacers, carburetors, timing, cam timing to get the best results and then repeatability.  If all that is done properly, then the dyno sheet will be proven accurate at the strip.  JMO, but I have done both the chassis dyno scene and the dyno scene on many engines over many years.  Chassis dynos are just as susceptible to manipulation as an engine dyno.  Joe-JDC

[Heo]

My wifes uncle have a chassis dyno and do some high end
rally cars there im going to take the Galaxie there to tune
it.
What numbers i get in the end compared to another dyno
is not that interesting as i see it. Just to tune my combination
       

[2VNTG68S]

I can't take my car on the strip unfortunately (convertible and I don't want to put in a roll bar).  My ass-o-meter guess is that it would do low 12's.  Even though the chassis dyno numbers were a surprise it pulls plenty hard.

[Heo]

Well i hear the young guys with their turbo this and that talk about using a certain chassi dyno
beacuse it gives the highest numbers yeahh right

[Barry_R]

Chassis dyno numbers are only useful for comparison during tuning THAT car on THAT dyno.  We'd probably be better off is they just gave us a number in percentages from one to one hundred based on pull comparisons.

I once took my car to one of those chassis dyno "contests" at a Car Craft show.  At that time it would run between 10.40-10.80 depending on the track and weather.  It laid down a solid 385HP on the dyno.  Some guy with a 455 70 Grand Prix with a catalog cam and a set of headers made 400...car was three seconds slower in the 1/4...

[Heo]

Chassis dyno numbers are only useful for comparison during tuning THAT car on THAT dyno.  We'd probably be better off is they just gave us a number in percentages from one to one hundred based on pull comparisons.

I once took my car to one of those chassis dyno "contests" at a Car Craft show.  At that time it would run between 10.40-10.80 depending on the track and weather.  It laid down a solid 385HP on the dyno.  Some guy with a 455 70 Grand Prix with a catalog cam and a set of headers made 400...car was three seconds slower in the 1/4...

Yes thats what im talking about i can tune it  on that dyno what ever that numbers are.  What nr another dyno shows is of no interest for me

[ACHiPo]

I agree.  My focus has always been on street cars, where the real details are in how good it runs from idle to 4500rpms, so a dyno doesn't really mean as much.

I wish my local drag strip hadn't closed down (again).  It was a lil 1/8 mile strip about 6 miles from my house.  Made it nice to go off and mess around for a Friday evening.  There is another track an hour away, but that prevents the spotaneous 8pm "hey lets go to the track"

What is the best way to assess/tune performance for the street?  I was thinking a nice flat torque curve down to 2500 or so RPM was a good indicator, but even that would be run at WOT, so I'm not sure it indicates anything other than squeeling the tires at low RPM?

[Drew Pojedinec]

Drive it.

Drive it everywhere, take the kids to boy scouts.  Drive 50 miles in one direction and 50 miles back, try to improve fuel economy while not losing any power.  Get it really stupidly hot racing around then sit at a redlight for 2 minutes.  Go off into the country roads and tear them up and then pull into a gas station and park the car while the fuel boils and try to restart the engine.
Drive it 40 miles to the drag strip and get really horrible times because you have street tires and probably 500ft lbs of torque, then drive it home.
Let the car idle for 30 minutes as see how hot it gets on the hottest day.
Anytime a little issue pops up, fix it.

That's how I do it

[2VNTG68S]

Drive it.

Drive it everywhere, take the kids to boy scouts.  Drive 50 miles in one direction and 50 miles back, try to improve fuel economy while not losing any power.  Get it really stupidly hot racing around then sit at a redlight for 2 minutes.  Go off into the country roads and tear them up and then pull into a gas station and park the car while the fuel boils and try to restart the engine.
Drive it 40 miles to the drag strip and get really horrible times because you have street tires and probably 500ft lbs of torque, then drive it home.
Let the car idle for 30 minutes as see how hot it gets on the hottest day.
Anytime a little issue pops up, fix it.

That's how I do it

This is what I've been trying to do.  The chassis dyno helped with most aspects of the tune but now I'm playing around with cold start, warm start, seeing how it responds to different cruising parameters etc...  From my perspective the initial dyno tune at Barry's was a great baseline to make sure we were in the ballpark.  The chassis tune got me closer with all the variables of exhaust, intake restrictions, etc...  I feel that WOT is about as good as it will get.  Now I feel I'm 90% there and just filling in around the edges.