Miata Mailing List: December 1997, Message #251
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From: 	GibbP@aol.com

Subject: More Dyno Data.....14 psi

Date: 	Tue, 2 Dec 1997 23:40:32 +0000





I just got back from the HMS Motorsport dynojet and thought I'd post the most

recent results......even though they are a bit disapointing!



I increased the boost on my 92 1.6 Autorotor Plus to 14 psi today by going to

a slightly smaller pulley. The results are as follows.



All numbers are corrected for temperature and pressure and are at 14 psi max

boost, backing down to about 13-12.5 above 5k. I used regular 93 octane pump

gas.



Max HP          226.1 @ 6850 rpm

Max Torque     212.6 ft/lbs @ 4750 rpm



While the torque numbers show a very nice increase, the peak HP numbers are

low by about 15-20 HP......we'll be working on that next! :)



In real world terms there is a SUBSTANTIAL gain in torque ( as compaired to

the 12psi numbers ) from 2200 rpm to about 4800 rpm. Above that the

differences are smaller. Indeed, the bottom half of the power curve shows the

expected 20-23 hp gain while the top half netted only about 10-12 hp. I think

we may know the reason for this.....



At this point the car is producing over 200 ft/lbs from 3200 rpms to about

5500 rpm. this translates into a very drivable car, as maximum acceleration

is available right in the range you use most in street driving. Indeed, the

"torque curve" is really very flat with over 175 ft/lbs available from2500

rpm to 6700 rpm. Boost is instantanious from just off idle, to redline at

7500.



In real world terms, the car, as currently setup is faster than most anything

out there. Monday a "fellow" in a Supra Twin Turbo tried to pass me on the

right as I was going about 70 mph. As he closed to about 1 car legnth I

simply floored the throttle in 5th and reeled him in in the space of a few

hundred yards. He then downshifted to 4th, but to no avail.....I simply

stayed in 5th and easily pulled away. Later that night ( must have been a

full moon ) some kid in daddys' Saab Aero cut in front of me at 80 mph and

then proceeded to slow to 65. I simply pulled to the left, came up even with

him, smiled and waved and quickly left him fading into the dark......so much

for $45,000 "sports sedans". 



CAUTION!!!!!! BORING NUMBERS BELOW!!!!!!!



rpm       ft/lbs       HP



2100     138.5     55.4

2200     154.3     64.6

2300     162.8     71.3

2400     172.3     78.7

2500     175.8     83.7

2600     178.8     88.5

2700     184.7     95.0

2800     187.2     99.8

2900     189.4     104.6

3000     194.7     111.2

3100     196.5     116.0

3200     201.5     122.8

3300     200.6     126.0

3400     203.7     131.9

3500     205.2     136.7

3600     205.8     141.1

3700     207.0     145.8

3800     206.8     149.6

3900     209.8     155.8

4000     208.6     158.9

4100     209.5     163.6

4200     211.2     168.9

4300     210.7     172.5

4400     210.7     176.5

4500     208.5     178.7

4600     210.6     184.5

4700     212.3     190.0

4800     211.0     192.8

4900     204.8     191.1

5000     203.3     193.6

5100     203.3     197.4

5200     203.1     201.1

5300     201.6     203.4

5400     202.3     208.0

5500     199.6     209.0

5600     196.2     209.2

5700     193.3     209.7

5800     194.4     214.7

5900     193.2     217.1

6000     189.8     216.8

6100     190.3     221.0

6200     188.1     222.0

6300     186.5     223.7

6400     184.9     225.3

6500     182.8     225.5

6600     177.5     223.1

6700     174.9     223.1

6800     173.1     224.1

6900     171.9     225.9

7000     166.7     222.2

7100     162.3     219.4

7200     159.6     218.8

7300     154.2     214.3  





What these EXTREEMLY boring numbers tell you is that the Autorotor Plus

supercharge is making SUBSTANTIALLY more power below 3100 rpm than any of the

published results of any of the turbo Miatas! Don't believe me? Look at the

dyno charts. Even Shiv's "torque monster" doesn't match the output of the

Autorotor Plus untill 3300 rpm. Bills' FM Turbo doesn't exceed the torque

produced by the Autorotor Plus anywhere on the curve. Now when Bill uses

nitros all bets are off! :).....Oh NOOOoooooooo!!!



At least untill Shiv gets his new turbo to a dyno I can confidently say that

a well designed supercharger WILL make more power on the bottom and offers a

real drivability advantage in this range when compared to a turbo......(flame

suit on, marshmellows ready)



Gibb Phenegar

92 Autorotor Plus @ 14 psi  



ps. Don't you just love competition.......:)