Chassis Dyno - Risk/rewards

[JIMOCO]

I am considering having my car dyno'ed. After reading the "Drive Line Loss" thread I realize that the results can vary but I thought it would be interesting to see the results. I have also watched a number of videos where the testing had catastrophic results - engine failure, breaking free from the restraints. What is everyone's thoughts on chassis dynos and the risks versus rewards?

[Bob Cowan]

What is your goal? Do you just want to see how much power you're making? Or do you want get the tune dialed in better?

If it's to get the tune dialed in better, I think it's probably worth it. You might be surprised at how much better and efficiently the car will run.

If it's just to see, It's probably not worth the effort. But that's just my opinion, I could be wrong.

[NAZ]

Hot Rod Magazine had a good article on dynos -- Google it here: http://www.hotrod.com/articles/hrdp-...is-dyno-guide/

I wouldn't worry about the car getting loose or engine damage. If you're just curious or looking for bragging rights then the cost vs reward is totally subjective and only you can determine the value. The greatest value from a dyno is in testing / tuning but you need a well thought out test plan before you go and have all the parts on hand needed. Discuss the plan with the dyno operator when you make the appointment. I've never heard of any problems with street tires but there are some issues using drag slicks on a chassis dyno.

Have fun and let us know how it went.

[walt mckenna]

What is your goal? Do you just want to see how much power you're making? Or do you want get the tune dialed in better?

If it's to get the tune dialed in better, I think it's probably worth it. You might be surprised at how much better and efficiently the car will run.

If it's just to see, It's probably not worth the effort. But that's just my opinion, I could be wrong.

Bob's reply reminded me why I dyno'ed my car at the Ford Nationals in the first place. I simply wanted to hear it run up the RPM scale under load. I track the car whenever possible and friends have told me that it sounds good at high RPM and I wanted to appreciate that sound without the helmet and wind noise. Some might say it was a waste of $80 bucks, but it was a bucket list item for me and now I can listen to it whenever I need a little music (almost every day).

[JIMOCO]

It is more of satisfying my curiosity and have a comparison point. The engine builder told me the horsepower rating at the fly wheel. I believe them but it was not dyno'ed and I would like to see what I'm getting to the ground while getting some reasonable assurance that the fly wheel number is realistic. Thank you for your replies, they have been very helpful.

[Papa]

I had my 1970 El Camino chassis dyno tuned and they were able to get about 20 h.p. out of it that I wasn't just by getting the jetting and timing dialed in. I think it cost me ~$210.00 and I think it was worth the money spent.

[GoDadGo]

Putting the car on a chassis dyno is great for bench racers; however, real world figures will uncovered on the 1,320' (The 1/4 Mile) and will scratch more than a few itches in the process.
My recommendation is to bring your roadster to the dragstrip and make a few solo passes so that you can concentrate on your car and your driving skills.
Just take it slow if you've never made a pass at the strip in a car as potent as your Factory Five.
You will learn more about your car and yourself than any dyno can ever tell you.

[JIMOCO]

I plan to do that as well. There is an 1/8th mile near me that I want to visit. I have had several high performance cars and have been down the drag strip many times. I am looking forward to finding out what my Cobra can do. I will try a 1/4 mile later this summer.

If the dyno results are unfavorable I will look into tuning but for now I just want to get a baseline. Thanks for all your thoughts.

[bobl]

I have an engine dyno and have tuned hundreds of engines. I've never had one leave making less power than it started with( a couple in a basket though)! It's well worth getting an engine tuned on a dyno. It's pretty common to see 20-30 hp gains from proper tuning, even on a good running engine. One of the most important things you'll come away with is exactly where your peak torque and HP numbers are. Then you can set up and drive the car around those parameters. It very well may be a lot different than you thought. So if you're going to spend the time and money to get it on the dyno, get the air/fuel data and tune as needed. It will be worth it. It doesn't really make any difference what the numbers are compared to another dyno or car. You just want to get your data and optimize your setup. If the numbers are way out of line then it could indicate some deficiencies worthy of looking at.

Bob

[JIMOCO]

Hi all. Did the dyno today. Results were favorable. Average of three pulls was 325.5 RWHP and 343.8 torque. Less than expected on HP but I am pleased. At a 15% rule of thumb loss, I though I would be closer to 360 RWHP. Torque was in line with expectations. It was very hot and humid here in PA so that will have skewed the results compared to a cold day. I now have a plan with the shop to do some carb adjustments (at a discount since they did the original pulls). They think they can get another 20+ HP with some adjustments and jetting changes. I think I will wait until the fall to make the adjustments. Thank you for all of your input. (GoDadGo, I called my local drag strip and could not run without a helmet. They do not rent them and since it was Sunday, I did not have a rental available. I will try again soon.)

Jim

[GoDadGo]

Jim,

Your Road Rocket Has Great Numbers From Only 347 Cubic Inches So Don't Fret!

347 Cubic inches yielding 325.5 rear wheel horse power are very respectable and in my book. If you calculate the drop at the wheels, then your flywheel HP figures get to the 370-375 range with over 390-395 lbs of torque.

Get an nice full face Snell/SA approved helmet, a neck donut, jacket, gloves, arm restraints and you'll be ready for any drag strip or autocross pad.

Happy MK-4 Motoring!

Steve