Should I dyno tests after installing lighter wheels?

[makesdrivingfunagain]

Obviously I am an amateur (at best) however I have considered renting a dyno after I install my new wheels. hopefully this year, it would be a dyno jet. My new wheels will definitely be in the 5.5lbs lighter per wheel plus 1 lb lighter per tire. they will be 16" with a 205/55/16. So a total of 6.5 lbs per corner or 13lbs for the rear, which is where the power is measures. I was wondering if you think I should dyno test to see if there will be any gains? I dyno tested my car in the Automatic transmission on a dyno jet and made 169.44 hp and 144.44 tq with very near 100% octane . I could do this next test with just 91 octane and the new lighter wheels and compare. Or I can run 91 with the new tires on and then change to the stock 17 with michilins and compare immediately. Do you think or know if I will see a difference or a waste of money? Any help would be appreciated. I will be taking this car to the same dyno to make the test as accurate as possible to determine the differences before and after. There has been no other modfications to this car as it is 100 % stock. The car had around 2000k before and will have well over 11,000 miles when the next test takes place Seriously I would appreciated your help!! sincerely thanks for your help!!

[gramicci101]

If you've not done anything to change the power, I can't see it being beneficial.

[Model Citizen]

Are you doing this for science? Bragging rights? World peace?


Ive never dynoed a car ever. Why? Because as much as i like the idea of subjective numbers i like money better.

[kiichiro]

Just do it

[ZionsWrath]

Well if you add any performance parts that are supposed to add power you should get a dyno (+tune)

Wheels? not so much...

But I'm sure a lot of people on here would be interested in a dyno of heavy wheels vs light wheels with no other mods.

[GrippinandRippin]

True. It would be something you pretty much never see. Curious.

At least you would have a decent baseline with no other mods. Any power mods would make the before and after on the wheels irrelevant.

Sent from my SCH-I545 using Tapatalk

[mlinder]

I would leave the gas quality the same so your not changing that variable. Then you'll know for sure how much improved performance you have. If you go with a lower octane fuel with the lighter wheels than your first dunno it won't be a true comparison. Either that or so wimp with stock, test them then switch out to the new and test. I'd like to hear about your results.

[makesdrivingfunagain]

Yes, I am personally interested in the science or the data of changing wheels. It seems many say that unsprung weight is huge and that it has a multiplying affect of weight loss (like 1 lb of unsprung is equal to 2-3lbs of sprung weight). I have seen a while ago a Honda in a magazine article lose power do to a big brake kit, it was like 1-3 hp or something. I am an amateur at best but would like to see the truth of light wheels etc. These new wheels would be 16% lighter than stock. If I get the new wheels I will do this experiment. The wheels and tires in 16" inch form will lose 6.5lbs per wheel.

[stugray]

Originally Posted by makesdrivingfunagain

Yes, I am personally interested in the science or the data of changing wheels. It seems many say that unsprung weight is huge and that it has a multiplying affect of weight loss (like 1 lb of unsprung is equal to 2-3lbs of sprung weight).

Lightening the wheels (and corresponding change in unsprung weight) helps in the handling of the car because it makes the suspension more responsive to the road because it can "get back to the road faster" after small bumps.

Reducing the rotational inertia of the wheel itself will not make a noticeable difference in horsepower because the tire makes the greatest contribution to rotational mass of the tire/wheel system.

So my bet is that any change in effective horsepower by lightening wheels will be within the margin of error of consecutive dyno pulls.

[fatoni]

There is a grm article about this kind of thing. Much more informative than a dyno. The difference you would see on a dyno is going to be much smaller than the margin of error

[makesdrivingfunagain]

Originally Posted by fatoni

There is a grm article about this kind of thing. Much more informative than a dyno. The difference you would see on a dyno is going to be much smaller than the margin of error

Thanks for your help...!! As I didn't think about the margin of error issue. When I did my dyno runs they all varied by a horsepower and one or 2 ft lbs.


Fatoni, I am unfamiliar with grm, is that a magazine or an abbreviation? Thanks, seriously!!

[fatoni]

Originally Posted by makesdrivingfunagain

Thanks for your help...!! As I didn't think about the margin of error issue. When I did my dyno runs they all varied by a horsepower and one or 2 ft lbs.


Fatoni, I am unfamiliar with grm, is that a magazine or an abbreviation? Thanks, seriously!!

grassroots motorsports. they took a miata to an autox with two sets of rims with a 3lb/corner difference in weight. the heavier rim was actually faster that day. i dont believe that a heavier rim is faster but i believe that the concept is highly overrated as far as performance goes. maybe subjectively there is something to be gained but you arent going to discern that from a dyno or laptime.

[makesdrivingfunagain]

Yeah I saw something on the net about dynoing a 3lbs per tire difference and there wasn't one. I would like to see where the barrier can be broken. In my unprofessional opinion I would like to use a lighter wheel say a TWS 10.7lb 16x7 rim or a volk 16x7 vs the stock 20.1 lb rim and the 20lb tire vs a 19lb 205/55/16 tire. We would lose nearly 20lbs verses stock on the rear wheels. Then we could put on a 17x8-or 9 (17x9 enkei rpf1 black weighs 15.9)lbs with a good xtreme performance Bridgestone RE11A 245/40/17 weighs 27lbs. So in this case a total weight difference verses the stock 40lb setup (17x7 wheels and michiline tires) compared to the enkei 42.9lbs setup with bridestones we are only talking 3lbs. But compared 42.9 or 43lbs compared to the set up I am going to run a 33.6lb we are talking nearly 10lbs per wheel, If I was to change to a TWS 16x7 I would lose an additional 4lbs so a total of 14lbs per corner. It makes me wonder when we can see a difference on the dyno verses feel a difference.

[D K]

Going to heavier wheels is like adding weight in the car.
Might accelerate slower but engine power is the same.

D