The Lotus Cars Community banner

1 - 12 of 12 Posts

·
Registered
Joined
·
5,607 Posts
Discussion Starter #1
I thought I'd make this thread as I will be dyno testing mine perhaps tomorrow in anticipation of adding modifications. I want a baseling. I feel its rather important and I myself would like to know.

How does one dyno the elise? Standard dyno's usually strap down the A-arms. I've spent many hours on dyno jets but never with a car like this this that you cannot strap down the conventional way.

I'll be using a standard elevated dyno jet. However I know some here use Mustang.
How does it work with each particular type?

Suggestions from those who have done so already?


Thanks
Jenn
 

·
Registered
Joined
·
803 Posts
how to tie down an Elise

I do not think there is any good way and care must be taken.

I supervised the dyno runs on my Elise yesterday. If you look at the picture, you can see they did put loops of webbing around the bottom A arm as tie downs.

Since the Dynojets are elevated rollers, the car needs to track straight and needs to be secure. That means you need to put some stess on the tie downs. You need to have confidence that the person doing the work knows what they are doing. A minimum tension needs to be applied or you will start bending things.

Make sure the straps clear the body work and diffuser.

Worse, there are some large forces going on during the pulls. Make sure they remove the throttle at the end of the run gently. Also watch the engine move! I suggest stronger engine mounts might be needed for extreme exercises.

Also note the two big fans in front and the blue fan pointed at the intake. The little back box behind the tail pipes is the sniffer.

Sorry for the late response. I try not to live on this forum even though it is addictive. I try to read it ever other day or even once a week...

Michael
 

Attachments

·
Registered
Joined
·
5,607 Posts
Discussion Starter #5
Hmmm.

Where I dyno I am the one in the car. Not the operator.

Also, not strapping the car down tight is an old dyno trick. It yeilds more horsepower because there is less resistance to overcome. Some places will only lightly cinch the car down because it creates less drag on the car and yeilds more power...its an old trick of the trade and one I never understood.
Not saying people here would do that however due to the sensitive nature of the elise people are going to be using different pressures and strap down methods which are going to yield different numbers.

The good thing is that I wouldnt be bothered with what person A makes or person B on this forum. Just worry about your own baseline and stick with that same dyno as you make changes to the car.

Michael,
Even with those little blue fans ( power plus fans..we have several in our garage) the car is still going to heat soak. How did your runs look from start to finish?

And I wouldnt put too much salt in the air fuel ratio's you got from that sniffer. Some are close to accurate, some arent.







You know what we need for this car and there are only two in the US right now? The ROTOtest dyno. It bolts up to your wheels.


http://www.rollingroad.com/products/vpa/index.htm]

Ive wanted to purchase one of these for a long time. At one point I contacted the company in Sweden but it was difficult to converse because of the language barrier. They have a few guys who speak english that they send over when you purchase though. As far as I know there are only two in the US. One is in Colorado.
 

·
Banned
Joined
·
6,941 Posts
It can be strapped with care. And the front can be tied down through the wheels, but the shop may need to use some more strapping to be able to do this. Very good point about the tie down pressure and a possible effect on the results. BTW Dynapak dynos also use the no-roller-direct-mount-to-hub-approach. I suspect that part of the concern Lotus is expressing is more related to tying a car down for trailering in which case the bumps, stops and so forth can shift the weight around quite abit.
 

·
Forum Founder
Joined
·
29,083 Posts
Sorry Jenn, we (Shinoo and I) were kicked out of the area where they did the dyno, my second complaint about the company that did it (first was we had to wait 90 minutes to get on the dyno). I saw straps like Michael shows in his pics and everything seemed okay.
 

·
Registered
Joined
·
5,607 Posts
Discussion Starter #8
Not a problem. I'm not sure what we're going to do. I was going to dyno it today but we were both feeling under the weather.

I can't believe they kicked you out! Things must be alot different around here because all the dyno shops have the owner run the car while they man the computers. I dont think I'd ever let a shop just have my car to dyno. It would be like handing my baby over and letting them take it in a back room or something without me there.

I'll figure out something.
 

·
Registered
Joined
·
140 Posts

·
Registered
Joined
·
2,195 Posts
I love how the Rototest unit uses the car to drive the huge air blowers. Clever and elegant..

Since they've already measured the power, they're just going to throw it all away into friction anyway, might as well use it to move a huge amount of air.
 

·
Registered
Joined
·
5,607 Posts
Discussion Starter #11
I meant Rototest Not Dynapak, moreso for its software and mechanical features than simply the bolt to the hub deal.

Dont need to drive to Alabama, which is a LONG way from me.....There's a guy at the carnival that has two dynapaks that has "load" races with them. It guess maybe that turned me off. :)


I have 2 Mustang Dyno's and 3 Dyno jets within 20 minutes of my front door. I'll have to work something out.
 

·
Registered
Joined
·
803 Posts
more info on dyno run

OneFastLotus and others,

There was no slippage between the dyno drum and the tires. The car was tied down enough to prevent it. I suspect that you want a tight fit to prevent slipping but not so tight that you compress the tires more than if the car were sitting on the ground. The picture I posted here obviously shows the rear wheels in motion. I checked my high resolution pictures of the car strapped but stationary and noted that the tires were not overly compressed, but appeared normal like on the ground.

The software on the unit was recently upgraded and therefor more accuracy implied. They were using version 7 for those counting. I will be posting more pictures and the scan of the dyno sheet on my site in the next several days.

The operator noted that the runs were extremely consistent. This was unusual compared to other cars. In some cases the power developed varies 5-10 horsepower. My curves were almost identical. It might have been possible for heat soak to influence the third run. We did two runs, talked a bit and looked at the results and then did the third run. No change. They were impressed.

The sniffer was one of the more elaborate I have seen. I was impressed with the connection, the fact it was actually an active sniffer with its own fans, and its consistency. But you are correct, that all this equipment requires constant and correct maintenance if it is to provide correct and consistent data.

I agree about not putting much importance in the actual numbers. Ambient temperature, humidity, maintenance of the unit, operator variance, and the phase of the moon all play a part in determining actual horsepower. I just wanted some confirmation that I did not do anything wrong while breaking in the car and to provide a reference in case I decide to add go fast goodies later.

(I doubt I will add any go fast goodies any time soon. The car has plenty of power for my use. I know some of the tricks employed to get more power and the risks associated. Right now I believe Lotus did a good job tuning this engine and that it is not likely, but not impossible, for someone to do a better job.)

I agree with Stan that holding down the front end might be better done by strapping the wheel. I do not like pulling on the suspension pieces and do not want to stress them beyond what it takes to move the car. The suspension on the Elise is not like a lot of other cars, so the experience of the dyno operator is important. Do not hesitate to ask questions or take your car back if you do not like what they are doing.

Michael
 
1 - 12 of 12 Posts
Top