Airboy results with different wheel/tire combos?

Has anyone experimented to see what effects, if any, different wheel combinations play on the Airboy dyno?

 

I swapped over to my summer wheel/tire package, which consists of Team Dynamics 18x8" Pro Race 1.2 wheels and Kumho 235/40/18 SPT tires, running 35 cold front and 37 cold rear. Compared to the stock set-up, I'm showing the following:

 

Down 30 ft. lbs torque

Down 23 whp

60-80mph took an additional 1/4 second and 50-80mph took an extra 1/2 second.

 

I changed the tire sizing in the spreadsheet and the 25.4" diameter is very close to the 25.25" that I measured.

 

I can get my plots to overlay by adding 600lbs to the vehicle weight.

Was the temp. much cooler the first time you used the sheet? If so, that's part of the problem, if not most of it. Also, did you use the same road for testing?

Yep, same road and IAT was within 2*F.

 

Timing was the same.

Load was almost identical, if not a smidge higher on the run with the larger wheels/tires.

Have you run a Learning View shot recently?

Both runs done after a fresh ECU reset and IAM back to 1.0. Obviously fuel learning was not set-up in either instance, they are always within 2% across the board, but there was no timing pulled in either log and there was no FLKC in either instance.

What did you change in the re-flash? Any parameters?

Any difference in wheel weight and amount of gas in the tank?

 

FWIW, when I swap from summer to winter 18x8 225/40/18 vs 18X7.5215/45/18..my whp number stay exactly the same give or take 4-5 whp.

The only thing I'm messing with right now is trying to get boost to come on a little quicker. After 3,200rpm, the maps were identical.

 

RE gas in the tank: Yes, the lower run was with approximately half a tank and the higer run was with approximately 1/4 tank, BUT these variations in weight have never caused that kind of swing in the Airboy dyno. It's usually a few hp between 1/4 and 1/2 tank.

 

RE Wheel weights: Yes, the summer set-up is noticeably heavier, but I have not weighed and comapred to give a definitive answer on the specific differences. I will try to weigh this weekend. From what I know of the wheels/tires, thier combined weight should be 46lbs. per corner. Anyone know what the factory 17" and RE092 weigh?

I wish i could help.. but mostly I just want your wheels please!

 

Where did you get your team dynamics? my favorite wheel of all time and I want a set in 18x8 and black... YUM

Has anyone experimented to see what effects, if any, different wheel combinations play on the Airboy dyno?

 

I swapped over to my summer wheel/tire package, which consists of Team Dynamics 18x8" Pro Race 1.2 wheels and Kumho 235/40/18 SPT tires, running 35 cold front and 37 cold rear. Compared to the stock set-up, I'm showing the following:

 

Down 30 ft. lbs torque

Down 23 whp

60-80mph took an additional 1/4 second and 50-80mph took an extra 1/2 second.

 

I changed the tire sizing in the spreadsheet and the 25.4" diameter is very close to the 25.25" that I measured.

 

I can get my plots to overlay by adding 600lbs to the vehicle weight.

 

Always measure the actual tires diameter.

 

I had a set of tires that were over 1/2 inch smaller then the numbers would suggest, got worse as they wore down.

 

I bet your old tires were a lot smaller then you though, and if you had accurate numbers for the diameter of both they would line up within 4 or 5 whp, assuming same road, temp, etc.....

LBGT, I will go and measure the stockers again. Yes they were quite worn. I'll plug that back into the spreadsheet and see what I get when I get home. How are you guys getting accurate diameter measurements? I was eyballing a tape measure across the outside diameter of the tire while on the car. Like I said, my measurement of 25.25" came very close to what was calculated (25.40") when I input 235/40/18 into the spreadsheet. I left it as 25.40" and even tried it back at the 215/45/17 size and the calculated power was not much different. Just a few HP.

 

LGTBiggie, a couple of my buddys imported these in specific Subaru fitment for a while back in 06/07. You can see the thread I started about them here: http://legacygt.com/forums/showthread.php/new-wheel-option-legacyi-45548.html?t=45548&highlight=team+dynamics

 

That venture has long soured. Not sure if you can still find these in the states with the correct bolt pattern, offset and hub bore.

I use a straight edge in the tire, hold it level, measure to the ground.

 

Don't forget to take wind into account.

I use a straight edge in the tire, hold it level, measure to the ground.

 

Don't forget to take wind into account.

 

Thanks!

 

IIRC, both days were calm.

Seems changing the wheel diameter is having zero effect on my results. I can even put in wild numbers for tire size with no change to reported power/acceleration. Any ideas?

Seems changing the wheel diameter is having zero effect on my results. I can even put in wild numbers for tire size with no change to reported power/acceleration. Any ideas?

 

You have to change the RPM to speed conversion in the spreadsheet.

You have to change the RPM to speed conversion in the spreadsheet.

 

Thanks LBGT. I'll try it tonight. It's the first time I've had to deal with a different wheel/tire package.

Same here...All my prior logs with the old setup was with the stock wheels/tire setup.

Well, that got me closer, but still missing about 13 ft. lbs. and 10 whp. Now my 60-80 mph is within ~ .1 and 50-80mph is within ~.2. Nonetheless, I have my new baseline.