neit_jnf

iTrader: (17)

Went to a DynaPack Dyno today, temperatures in the 70's, raining (100% humidity). They have the dyno calibrated to read similar to Dynojet numbers.

Did 3 runs, the last one with the boost controller off (~8 psi) just to test how I normally drive the car. I only use high boost (13.5 psi) for fun runs

They put a wideband in the tailpipe, I leaned to 12.5 at the top of the rpm range at high boost and they recommended a fuel pump. The low boost and lower rpm high boost afr was between 11.1~11.5.

I've heard there's a difference between pre-cat and after cat O2 readings, anybody knows? I'm using the stock cat.

Here are the results:

13.5 psi
315 whp @ 6551 rpm
246 ft-lb @ 5150 rpm

there's a 50 whp/35 ft-lb jump at transition

8 psi
250 whp @ 6881 rpm
188 ft-lb @ 5308 rpm

almost no transition

Power Mods:

M2 Stage 3 ECU
KnightSports EBSIII Boost Controller
HKS Twin Power
M2 Aluminum Intake
M2 Large SMIC
Bonez Coated and Wrapped DP
Racing Beat Dual Tip Cat Back

41500 miles old stock Engine and Clutch
11500 miles old stock spark plugs

https://www.rx7club.com/attachment.p...d=122340&stc=1

https://www.rx7club.com/attachment.p...d=122341&stc=1

potatochobit

iTrader: (1)

well the cat uses oxygen to convert the exhaust so there should be more near the O2 sensor, and less afterwards. 315 WHP is nice for daily driving i think.

neit_jnf

iTrader: (17)

so it means I'm actually leaner that it shows on the after cat sensor?

wait, I still have the airpump also, don't this adds oxygen? So basically I can't trust the afr reading?

potatochobit

iTrader: (1)

airpump only adds 02 at low RPMS and idle and such. not sure how it affects dyno readings... im sure one of the knowledgeable guys can answer this.


EDIT:

here look lol

http://www.fordscorpio.co.uk/cats.htm

books

iTrader: (8)

It I recall correctly a few years back, I dynoed with a wide band O2 sensor installed before a Bonez High Flow Cat with the dyno wideband in the tailpipe. I believe the dyno AFRs were 0.4-0.7 leaner.

rynberg

1. The tailpipe sniffer will read leaner than actual due to the cat....but not that much leaner...0.4-0.7 is probably a reasonable assumption.

2. The airpump stops working at 3200 rpm, therefore it has no effect on dyno AFRs.

3. 12.5 is too lean, although the actual readings may be more like mid to high 11s. I would back her down to 12 psi for fun runs. Since M2 tuned that ecu conservatively, either your car just needs more fuel than most or this a slight problem with your fuel system (dirty fuel filter, old injectors with poor flow/spray patterns, etc).

4. Adding a fuel pump won't do ****, given your mods.

5. Your numbers are strong for the boost levels...I wonder what correction factor they used on the Dynapack.

6. Any dyno session in which you don't blow up is a good one! In all seriousness, try to run hi-octane (100 unleaded) before a dyno session, it will give you a safety margin.

neit_jnf

iTrader: (17)

1. & 2. Thanks for the info

3. First thing I did after the dyno was setting her back to 12 psi. The fuel filter was changed at 30k, car has now 41,500. Every oil change I put a bottle of synthetic fuel system cleaner in the tank (don't know if it does anything)


4. my future plans include a PowerFC and maybe bigger secondaries to run 15 psi, the fuel pump will be needed then, right?

5. I was pleasantly surprised by the high numbers, I actually expected lower. They said they made it comparable to Dynojet. For comparison, A stock EVO put down ~230 and one with turboback exhaust and intake did 260. A WRX with catback did 189. I don't know how much these cars get on a Dynojet.

6. I usually run Sunoco 94 and never lower than 93. I haven't seen unleaded higher octane around

rynberg

4. You will need bigger injectors (and therefore a fuel pump) to run above 13-14 psi.

5. Sounds about right for a stock Evo, the WRX number seems high.

6. Lucky bastard, we only get 91 here in fruit-and-nut land....most drag strips and racetracks have 100 octane unleaded available.....better safe than sorry, although you're pretty safe with 94....

DrunkenGimp

iTrader: (3)

Rynberg, where's San Lorenzo? We have a number of 100 octane stations that arent near any strips or racetracks that I know of near los gatos. I actually did a google map search to find san lorenzo but it didnt show up haha