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Chassis Dyno...

Posted By: Al_Alguire

Chassis Dyno... - 12/23/10 04:27 PM

Anyone here use a chassis dyno to sort out thier cars?

I elected to not dyno my engine this time as it is basically a freshen up with a couple of small changes to the combo. However the weather has not been cooperating with getting it out and making some laps. The first race for me of the season is slowly creeping up and I would like to be ready to hit the ground running. made some other changes such as gearing and need a good idea where to start once we finally get out there. So the car has been sitting ready to rock. I would like to get it broken in and the fuel curve sorted out. Just wondering if this is a viable option or not? Any input?
Posted By: sg66mopar

Re: Chasis Dyno... - 12/23/10 05:08 PM

I ran mine on a chassis dyno this year. It really helped getting the jetting and timing dialed in. I also found a major glitch that had been causing a high speed miss. Never would have found that running the car down the track.

You probably already know that the numbers might not be very realistic but that's not what you're looking for anyway.

I found out the hard way that the chassis dyno can be hard on the car. I didn't have a fan on my trans cooler and should have let the engine idle a lot longer after every pull to get the trans fluid cooled down. The fluid got hot enough to burn the paint off the converter, cook the fluid and damage the high gear clutch pack.

Maybe in a way that was good because now I have a new cooler, twice the size of the old one with a 10" fan mounted on top of it, plus a trans fluid temp gauge.

I used an old pair of slicks that were about gone and I'm glad I did. The rollers will do some damage.

All in all I think it was worth the time and money. I don't know what you'd have to pay but my dyno guy didn't even want to take any money. He just wanted to see the car on his dyno. My wife left $125 laying on his desk and I hope that was enough to pay for his effort.

Posted By: TheOtherDodge

Re: Chasis Dyno... - 12/23/10 05:11 PM

I just had my junk on a chassis dyno last week and got everything tuned nice. The other option was to make a top gear blast on the street with the laptop, which was not an option! I paid $125.
Posted By: dannysbee

Re: Chasis Dyno... - 12/23/10 05:44 PM

Sorry to side track your thread Al but it looks like someone is holding out on us. What kind of numbers Theotherdodge.
Posted By: TheOtherDodge

Re: Chasis Dyno... - 12/23/10 06:04 PM

lol... I was wondering when someone was gonna ask that!

The numbers themselves were not great. After the pull, both the dyno operator and tuner (person that did my turbo and FAST system) asked how big my converter was. When I told them it was around 4500 they both said, "that makes sense"...

411 rwhp.

They said a big converter like that will "hide" the true power numbers. He said don't worry about the numbers, just go run it. If someone asks what hp did it make, tell them "411 rwhp, do you want to run?".

I was told a tighter converter would show much bigger numbers on the dyno but could hurt et if I was not able to spool enough on the line. And, I may have too loose of a converter but suggested I try it anyway to see how it does. Also, I don't know the shape of this converter. It may be slipping alot in upper rpms. Im thinking about getting a 3500 Precision Converter.

Right now, the truck rips the tires and runs killer. I was thinking it made around 500+ rwhp..

so anyway...I will report what it runs when our tracks open next year.
Posted By: Edge

Re: Chasis Dyno... - 12/23/10 08:04 PM

Sorted out my last combo as far as baseline jetting and timing also found a gremlin in the fuel system on the chassis dyno. Well worth the time and money. Did also damage a slick on the rollers as well.
Posted By: MegaDart

Re: Chasis Dyno... - 12/23/10 08:16 PM

As already mentioned they can be a valueable tuning aid but can also be hard on parts. I am like you and prefer an engine dyno on a new piece but not on rebuild, unless it's free!

After 3 unsuccessful trips to the track I finally put the Dart on chassis dyno when I first put it together. It would drive around and idle fine but would die in the water box

During a pull on the chassis dyno to figure out the constant flow mechanical injection I could see enough flames to cook a hot dog inside the injection hat
So we pulled the heads off to find the material between #2 and #4 was not there! Fixed that and severe valve float and the rest is history!!
I don't like the engine braking with that #2k drum driving the tires, pretty hard on parts.

check the video

[image][/image]
Posted By: Quicksilver440

Re: Chasis Dyno... - 12/23/10 11:15 PM

The key to the tires on the chassis dyno is to run them with lots of air pressure. I've never hurt a tire like that...and my brother owned a chassis dyno and ran cars on it daily.
Posted By: sg66mopar

Re: Chasis Dyno... - 12/23/10 11:28 PM

My slicks were at 11 PSI when we did the dyno pulls. That's as much as we could run in a 16 x 32 tire and still have most of the tread in contact with the roller.

I just wouldn't run a new set of of $700+ tires on one of those things.
Posted By: Old School

Re: Chasis Dyno... - 12/23/10 11:44 PM

when you use sticky tires, the readings will read much lower. even with drag radials.
Posted By: bonefish

Re: Chasis Dyno... - 12/24/10 12:08 AM

i ran mine on a chassis dyno and the guy made me put 23lbs in the tires and it hit the top of the tubbs and slit both my new goodyear 14x32,s but all in all we did get it dialed in pretty good.
Posted By: 2QUICK4U

Re: Chasis Dyno... - 12/24/10 03:10 AM

SCHOOL ME HERE.ON A ENGINE DYNO ITS ALL THE MOTOR. WHAT IF CONVERTER OR TRANS IS HAVING ISSUES,OR TRANS IS SLIPPING ENOUGH THAT YOU CANT TELL ON A DYNO. HOW ACCURATE IS THE CHASIS DYNO AT THIS POINT? THESE WILL AFFECT THE MOTOR HP AND TORQUE.
Posted By: Jeepmon

Re: Chasis Dyno... - 12/24/10 07:44 AM

Al, you know me and how inexperienced I am with racing.. but when we installed the nitrous in the 73 for PAO, we used the chassis dyno to set the timing and a/f ratio..

So for you and your car, I would recommend buying some time.. and if would help to cut the cost, I could bring the 70 up and tune it at the same time..
Posted By: DaytonaTurbo

Re: Chasis Dyno... - 12/24/10 08:01 AM

Quote:

SCHOOL ME HERE.ON A ENGINE DYNO ITS ALL THE MOTOR. WHAT IF CONVERTER OR TRANS IS HAVING ISSUES,OR TRANS IS SLIPPING ENOUGH THAT YOU CANT TELL ON A DYNO. HOW ACCURATE IS THE CHASIS DYNO AT THIS POINT? THESE WILL AFFECT THE MOTOR HP AND TORQUE.



I'm not an expert on the subject, far from it, but they can calculate converter/trans slip based on engine rpm versus rear wheel rpm.
Posted By: dthemi

Re: Chasis Dyno... - 12/24/10 03:38 PM

I have a chassis dyno in my Conyers shop and it's a great tool for set up, and finding problems. Everything from drive train, to A/F. I really don't care how accurate the power reading is. I use it more as a comparison of where we start, to where we finish. Jetting, nitrous, timing curves, and so on are a snap on the dyno. For sure a good data logger at the track can’t be beat, but at least traction is no issue on the dyno. I can grab the motor under full load and make sure everything holds together, and that the mix isn't going to be destructive. Better sitting still and finding a weak point than at 100 mph.
Posted By: MR_P_BODY

Re: Chasis Dyno... - 12/24/10 03:52 PM

Quote:

SCHOOL ME HERE.ON A ENGINE DYNO ITS ALL THE MOTOR. WHAT IF CONVERTER OR TRANS IS HAVING ISSUES,OR TRANS IS SLIPPING ENOUGH THAT YOU CANT TELL ON A DYNO. HOW ACCURATE IS THE CHASIS DYNO AT THIS POINT? THESE WILL AFFECT THE MOTOR HP AND TORQUE.



If the trans is slipping(for what ever reason) its
not giving a true number.... remember that the HP
number is just a calculated number based on the torque
reading at 5252... so if its slipping you wont see
the torque applied to the roller... all the chassis
dyno's that I have seen do the pull in high gear so
its a 1:1 pull for the torque reading.... they are
a useful tool and can save alot of time

Also.... turn off your caps lock... thanks
Posted By: HardcoreB

Re: Chasis Dyno... - 12/24/10 04:43 PM

Merry Christmas everyone!!! The only thing I might add is the effect of hoodscoop air pressure at speed will effect jetting. I have an old set of 14X32's with plenty of rubber left you can have Al if you want to pay shipping.
Posted By: Al_Alguire

Re: Chasis Dyno... - 12/24/10 05:56 PM

Thanks for the input guys. I dont care what the numbers are power wise. I know what the engine makes, it was dynoed last time and should be close to those numbers. I am more concerned with getting it broken in and making sure all is well and the tuneup is close. Also how hard it can be on the car itself, tires converter etc. I have a big cooler and fan so no worries there. I just wantto find the best tune up I can. If it dont happen I am sure we will be fine, after all it is basically the same engine and we have the old data.

Now gotta runa dn start and finish my Christmas shopping. Good thing I am a big ticket guy, usually makes it go quick. One gift a piece ya know
Posted By: bigtimeauto

Re: Chasis Dyno... - 12/24/10 08:01 PM

A dyno jet chassis dyno is a inertia dyno and thus measures power by rate of exceleration and engine RPM,(That is why you do the pull in high gear 1:1) then computes torque if you so ask it. Remember that the horsepower is what the dynojet is made to read first so as long as the operator sets the parameters correctly and the spark is clean and not erratic its results are usually correct .

I take EVERY car that leaves my shop to a friends dynojet before it goes racing. I would rather spend a hour or two on the dyno then a day at the track looking for a issue. The other bonuses of the chassis dyno is you are logging way more than the average car has, you can watch gauges, you are using the cars ignition and fuel system, you can video blower belts and....., you can make instant changes without worrying about the track and or the weather. I could go on but you guys see what i mean.

Tire pressure is critical, you need a minimum of 20lbs or the tire is not round!! and we tie he car down tight unlike a car sitting free going down the track. I use 25lbs. Do not use new slicks or the webbing on the rollers will tear them up. High power cars with drag radials or slicks need to be screwed to the wheels because when the dyno gets loaded they will slip on the wheel's and may come off the rim.


Its like other tools, when used correctly its great. Unfortunately it may not always be the *number* you are hoping for.

Quick example. Car is on the dyno and looking at the plugs versus the AFR we are lean at the top of the pull. We put more jet in it make another pull car is the same, we scratch are heads go back and look at all of our data fuel pressure, AFR, boost. Nothing there ok we measure our jets and throw in a even bigger set of mains, smaller air bleeds to, now we are way fatter up until 1000 rpm to our rpm limit. Hmmm fuel pressure is good, were fatter GUESS what, the single needle and seat holley bowls would not let enough fuel by them and the bowls were emptying out. this took 2 hours at the dyno. Nothing got hurt and the problem was found. New bowls a week later one pull all is good. So how would you have ever figured a problem like that out driving up and down the track making attempts every hour or so without a data logger on this guys 1200 RWHP street car??
Posted By: actionange

Re: Chasis Dyno... - 12/24/10 08:10 PM

These guys didn't have much luck on the chassis dyno...

http://www.streetfire.net/video/fail-900hp-dyno_2181566.htm
Posted By: bigtimeauto

Re: Chasis Dyno... - 12/24/10 08:17 PM

Quote:

These guys didn't have much luck on the chassis dyno



At the track he would have been in the wall on fire. So there you go another reason to use one.
Posted By: bigtimeauto

Re: Chasis Dyno... - 12/24/10 08:20 PM

Quote:


411 rwhp.

They said a big converter like that will "hide" the true power numbers. I was told a tighter converter would show much bigger numbers on the dyno but could hurt et if I was not able to spool enough on the line.



The dyno software should have show you/them exactly where the converter was slipping and where it locked up
Posted By: Al_Alguire

Re: Chasis Dyno... - 12/24/10 10:04 PM

Well I have new tires so that will be an issue for sure. Maybe I can find a set of 33x10.5's or soemthing to throw on there.

Thanks again for the info guys...
Posted By: Quicksilver440

Re: Chasis Dyno... - 12/26/10 05:04 AM

Quote:

These guys didn't have much luck on the chassis dyno...

http://www.streetfire.net/video/fail-900hp-dyno_2181566.htm



Those guys are idiots....
Posted By: Kam*Kuda

Re: Chasis Dyno... - 12/26/10 04:47 PM

Quote:

A dyno jet chassis dyno is a inertia dyno and thus measures power by rate of exceleration and engine RPM,(That is why you do the pull in high gear 1:1)



Any thoughts on the different of dynos and the type of tuning you can achieve.

The one with the 2 rollers (steady state?), I understand that you can hold a load at any given rpm and tune to that area

The one with the big roller (inertia?) would it extrapolate the data over the acceleration curve?

Are there benefits of one over the other
ie street/ strip (steady state)?
race car (inertia)
Carb versus Efi tuning?

I say tuning of an efi system on a 2 roller system dyno (street car) and there were able to hold load over a series of rpm ranges and adjust the timing/air-fuel for low to mid range and see immediate changes in #'s output.

This looked like a great system for a street strip car

Any thoughts?
Posted By: bigtimeauto

Re: Chasis Dyno... - 12/26/10 05:28 PM

Quote:

Quote:

A dyno jet chassis dyno is a inertia dyno and thus measures power by rate of exceleration and engine RPM,(That is why you do the pull in high gear 1:1)



Any thoughts on the different of dynos and the type of tuning you can achieve.

The one with the 2 rollers (steady state?), I understand that you can hold a load at any given rpm and tune to that area

The one with the big roller (inertia?) would it extrapolate the data over the acceleration curve?

Are there benefits of one over the other
ie street/ strip (steady state)?
race car (inertia)
Carb versus Efi tuning?

I say tuning of an efi system on a 2 roller system dyno (street car) and there were able to hold load over a series of rpm ranges and adjust the timing/air-fuel for low to mid range and see immediate changes in #'s output.

This looked like a great system for a street strip car

Any thoughts?




The dyno jet has a eddy brake that is how we do the steady stat efi tuning. Make sure you have a LOT of air flow to the radiator because they try and get hot quick!
Posted By: smokinwoody

Re: Chassis Dyno... - 12/26/10 07:03 PM

ya know AL I realy dont have faith in chassis dynos..I know I'll get flamed for what Im going to say but its thru experience that I have had..

one thing...who ever is going to do or does chassis dynoing had better know what they are doing...know the car first or whats in the engine like operating RPM...thats another key

we had the duster done when it had the 448 engine...we trusted the guy...were we wrong...he buzzed it up and said it was down on power from the year before...now how can this be...he changed jets and picked up some...then he adjusted the valves..and this is where it all went wrong..

he buzzed the engine so much...splitting my ear drums...like RPM I have never heard out of this engine...we were down on power so he popped the valve covers after he said he heard a noise inside while it was idleing...sure enough..spun bearings and now a slight vibration..

I pulled the engine to find a snapped rod and all sorts of internal damage...those were LY rods..told him they were...he buzzed that engine passed 8 grand...nice guy HUH??

I can see if the operator knows the engine or whats in it and knows how to tune...and has a good following..then I say fine...but I am still a firm believer on dynoing an engine after its been built to tune... and see how its all working together and to break it in...at least the bearings...and if its a flat tappet cam...

I know Im long here but that chassis dyno guy realy cost me a ton...and Im still Pissed..

Posted By: instigator

Re: Chassis Dyno... - 12/26/10 07:17 PM

Quote:

ya know AL I realy dont have faith in chassis dynos..I know I'll get flamed for what Im going to say but its thru experience that I have had..

one thing...who ever is going to do or does chassis dynoing had better know what they are doing...know the car first or whats in the engine like operating RPM...thats another key

we had the duster done when it had the 448 engine...we trusted the guy...were we wrong...he buzzed it up and said it was down on power from the year before...now how can this be...he changed jets and picked up some...then he adjusted the valves..and this is where it all went wrong..

he buzzed the engine so much...splitting my ear drums...like RPM I have never heard out of this engine...we were down on power so he popped the valve covers after he said he heard a noise inside while it was idleing...sure enough..spun bearings and now a slight vibration..

I pulled the engine to find a snapped rod and all sorts of internal damage...those were LY rods..told him they were...he buzzed that engine passed 8 grand...nice guy HUH??

I can see if the operator knows the engine or whats in it and knows how to tune...and has a good following..then I say fine...but I am still a firm believer on dynoing an engine after its been built to tune... and see how its all working together and to break it in...at least the bearings...and if its a flat tappet cam...

I know Im long here but that chassis dyno guy realy cost me a ton...and Im still Pissed..





Sorry to hear your bad incident...but I have always been the one in the car...doing what I feel needs to be done....I have always been friends with the dyno owners and they trust me to run the show...when I was on my buds mustang dyno the other month I spent about an hour just cleaning up the VE graph before I ever even let the motor up enough to make boost....

IMO the chasis dyno is a great tool to get a new combo worked out before looking like a dumbbutt out on the track.

I'll be going back next week I hope with the new megasquirt controlling the motor this time.
Posted By: MR_P_BODY

Re: Chassis Dyno... - 12/26/10 08:49 PM

Quote:

ya know AL I realy dont have faith in chassis dynos..I know I'll get flamed for what Im going to say but its thru experience that I have had..

one thing...who ever is going to do or does chassis dynoing had better know what they are doing...know the car first or whats in the engine like operating RPM...thats another key

we had the duster done when it had the 448 engine...we trusted the guy...were we wrong...he buzzed it up and said it was down on power from the year before...now how can this be...he changed jets and picked up some...then he adjusted the valves..and this is where it all went wrong..

he buzzed the engine so much...splitting my ear drums...like RPM I have never heard out of this engine...we were down on power so he popped the valve covers after he said he heard a noise inside while it was idleing...sure enough..spun bearings and now a slight vibration..

I pulled the engine to find a snapped rod and all sorts of internal damage...those were LY rods..told him they were...he buzzed that engine passed 8 grand...nice guy HUH??

I can see if the operator knows the engine or whats in it and knows how to tune...and has a good following..then I say fine...but I am still a firm believer on dynoing an engine after its been built to tune... and see how its all working together and to break it in...at least the bearings...and if its a flat tappet cam...

I know Im long here but that chassis dyno guy realy cost me a ton...and Im still Pissed..





I've only been on a chassis dyno once and after it
was strapped down and the sensors were in place...
the first thing out of the operators mouth was....
what do you want to turn it to
Posted By: bonefish

Re: Chassis Dyno... - 12/26/10 09:34 PM

the time i did it i was sitting in the car controling the rpm,s
Posted By: MR_P_BODY

Re: Chassis Dyno... - 12/26/10 09:48 PM

Quote:

the time i did it i was sitting in the car controling the rpm,s



I forgot I did it twice... once on the Woodward cruise...
they asked if I would display and run on the dyno...
in that one I was behind the wheel... but the second
time a operator ran it with me standing there
Posted By: bigtimeauto

Re: Chassis Dyno... - 12/26/10 09:50 PM

Quote:

ya know AL I realy dont have faith in chassis dynos..

he buzzed the engine so much...
I pulled the engine to find a snapped rod and all sorts of internal damage...those were LY rods..told him they were...he buzzed that engine passed 8 grand...nice guy HUH??




C'mon now, you had bad operator not the dynos fault!


First question is always what's done to the engine and how high do you want to take it. If its a new tune we always do pulls in 500rpm steps after 6K to see where it falls off without going past. As for where they make HP you can tell when the car isn't making power and you should pull your foot out of it.


Maybe this topic should have been titled *Chassis Dyno operators!*
Posted By: smokinwoody

Re: Chassis Dyno... - 12/26/10 10:30 PM

Quote:

Quote:

ya know AL I realy dont have faith in chassis dynos..

he buzzed the engine so much...
I pulled the engine to find a snapped rod and all sorts of internal damage...those were LY rods..told him they were...he buzzed that engine passed 8 grand...nice guy HUH??




C'mon now, you had bad operator not the dynos fault!


First question is always what's done to the engine and how high do you want to take it. If its a new tune we always do pulls in 500rpm steps after 6K to see where it falls off without going past. As for where they make HP you can tell when the car isn't making power and you should pull your foot out of it.


Maybe this topic should have been titled *Chassis Dyno operators!*



good point...
Posted By: sg66mopar

Re: Chassis Dyno... - 12/26/10 10:38 PM

I think we all know Al's sharp enough to be the one in the car. My Dyno operator asked ME what RPMs I wanted to go to on every pull and I kept my eyes glued to the tach. As soon as the HP started dropping off he'd wave for me to shut it down.
Posted By: smokinwoody

Re: Chassis Dyno... - 12/26/10 10:43 PM

the guy that did mine was a very arrogant owner/operator...I even told him that I would like to be in the car..he wouldnt hear of it..said insurance reasons..

I know AL would never let that happen..
Posted By: Quicksilver440

Re: Chassis Dyno... - 12/28/10 07:37 AM

Most chassis dyno guys will let you be the one in the car.....that way if anything breaks, it's on you.

I'd be pissed if they buzzed mine to 8K too...but thats why I don't let anyone else do it...but I would let my brother (on his dyno).
Posted By: 70Cuda383

Re: Chassis Dyno... - 12/28/10 07:46 AM

Quote:

the guy that did mine was a very arrogant owner/operator...I even told him that I would like to be in the car..he wouldnt hear of it..said insurance reasons..

I know AL would never let that happen..



then my next question would be "does YOUR insurance cover MY vehicle when it breaks on YOUR dyno when YOU'RE sitting in the driver seat?"


When I went to the engine dyno, he spun it till the power dropped off, but that was right at 6K. even stock parts should be good to 6K, I would imagine he would have asked what rods I had, piston weights, etc. had the motor kept pulling through 6500 rpm.
Posted By: Al_Alguire

Re: Chassis Dyno... - 12/28/10 04:19 PM

Well 8K will not be an issue. Last time on the dyno it was spun to 8500. All out I shift at 8300 Oh yeah if I cannot be in the seat it will NOT happen period. I went by my local shop yesterday and they are closed forthe week. So will go back next week and see whats up. Does not look like the weather will cooperate for this weekend either
Posted By: TheOtherDodge

Re: Chassis Dyno... - 12/28/10 04:32 PM

Hey Al, I like your hotdog!
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