Wo:Deep

Hey guys.

Due to my new engine build, I wasn't active in the forum since a long time..
But now, getting back into the Rx-7 business this topic started to interest me.

A little bit of "offtopic"
<OFFTOPIC>
Since I rebuilt my engine (Streetport, Mazdaspeed Rotor Modification, fine balanced everything) I thought about getting BNRs but you know what...
It's a pain in the *** for europeans shipping the old turbos there, getting them back, paying TONS of money for shipping and tax. So I decided to make my own twinturbos.

Luckily I'm working at the engine developement so it wasnīt only possible to search for the best parts (compressor wheel, turbine etc.) but also calculate a compressor map.
</OFFTOPIC>


With the engine running, and now mapped to 0.8bar (need another wastegate actuator) and no possibility to get on the dyno I tried to reacalculate some power numbers out of my logs.

There are two possibilities.

1. Phone app - "PerfExpert"
Lots of people say that this app is really good and should deliver quite accurate numbers

2. freeware Software "Virtual Dyno" (http://www.virtualdyno.net/)
It can automatically load the PFC logs.



About the setup:

Due to the fact that my setup is completely new and I have no experience and comparison with my new twinturbos, I donīt know if the numbers are accurate.

So, yesterday I've mapped another Rx-7 of a friend and we made some iPhone measurements and of course FC-Edit Logs.

We ran KnightSports EBS -controlled 0.7 bar which results in measuring in the PFC:
0.65bar with turbo 1
0.60bar with turbo 1+2 (>4500rpm)
(stock boost is 0.5bar measured inside PFC)

due to the fact that he runs stock injectors we are limited to this boostpressure.

With this setup (cold Air intake, bigger intercooler, 3" Exhaust turboback) I would have expected around 290-310hp and 370-390Nm (just a rough expectation).


The measurements:

We did 4 runs with 3rd gear (It's a bit tricky doing 4th gear runs on the street )
The result with the iPhone app was:

325,6hp and 393,2Nm (over all 4)

here is an example of a 3rd gear pull:
Perfexpert-Link

So the results are a little bit on the upper-limit of my expectations but nevertheless possible.

The problem:

when I'm loading the FC-Edit logs into the Virtual dyno and I'm using the (I think so) correct settings... I get completely different numbers:

Settings:
Car Weight: 1250kg (Itīs a JDM Type R2)
Occ. Weight: 200kg
Tire ht. : 25.04"
Gear: 3 (1.391)
Final Gear: 4.1 (manual)

Result:
The result in virtual Dyno is: 270hp and 320Nm

To get the same numbers I have to change the final drive to around 3.9 (which is the final drive of the automatic)

So does anybody know if the final drive of the JDM Rx-7 is 3.9 ?

With a changed final drive, the numbers are more expected: 310hp and 380Nm

here is the Virtualdyno plot of my friends car (red) and my car (green)
already with the "corrected" final gear.
As you can see, I have the boost problem on my car with the wastegate being pushed open on higher rpms.
Next year Iīll run 1bar to the top (can't wait to be April 2015 )
Maximum boost on both turbos after transition is now 0.85bar and falls quickly down to 0.75bar
mapping needs a finetuning, too. As you can see. this is only a quick and dirty mapping.





ToDo:

To be able to use the Virtual Dyno app We have to go onto a dyno to have compareable results...

and here you can help.

if someone of you has "real" Dyno results and could give me "real" Dyno Numbers and PFC-logs, I could tinker around in VirtualDyno to recheck my results.

I know... everyone of you would say that If anybody wants to have power figures, he should go onto a "real" dyno... but well... it might be helpful to get a rough information about the power without going onto a dyno.


So If you want to help checking the tool, please send me your dyno Info and PFC log to:

damnnice.motorsports@gmail.com

Iīll keep you updated about the settings in VirtualDyno to get the best results out of it.


Cheers, Marc

DC5Daniel

iTrader: (10)

We have used VD and Airboy for Subarus and Hondas, for the record they can be pretty accurate in comparison to when we strap these cars on real dynos. They do tend to read a hair high though.