Results:

Went to the dyno this morning early and it was already really hot out. i got the car on the Mustang dyno and this is what happened. i decided to datalog the runs also with my laptop and make corrections on the SAFCII if i saw it was needed.

first run: 141whp
this was about what i expected, but looking at the AFRs it was much too lean! i was getting 14.0-14.5 AFRs which was much leaner than i have seen on the street. so i dialed back the correction a bit on the SAFC...

second run: 150whp
a noticeable improvement but still too lean. corrections made again on the SAFC...

third run: 153whp
still improving a bit, and still a little lean in some spots (i was aiming for 13.0, but was still getting into the high 13s)...

fourth run: 154whp
pretty much the same as the third run. a little lean in some spots but i didn't want to go any richer since i would not really see that kind of load on the street. at this point i think things were also getting a little hot since i didn't cool the car between runs, they were back to back, and that might have leaned it out a little also.

i've attached the dyno sheet of the last run (ignore the two blue straight lines) and also the wideband datalog.

also click my sig for mods...basically it's an NA S5 with a stockport S4 block.

 

Good stuff, so you what was your final AFR reading ? for the max power you made ?

mid 13's ? ;low 13's or the 13.0 you were aiming at, and what were your egts ?

 

see the attached graph for the final run AFRs Azad!
no clue about EGT, i don't have a sensor. i'm running stock timing, maybe a few degrees retarded last time i checked with a timing gun, so EGTs are probably fine.

 

Very nice ...

The power curve is very much like my car, just a little less flat.

Did you do your pull in 3rd or 4th gear?

 

mods?

 

thanks. looks like my VDI could open a little earlier which would maybe smooth out that little dip in torque in the middle.

i don't quite remember which runs were 3rd or 4th, but i am pretty sure he did both. i think the last run was in 3rd.

powertrain related, it's stock S5 NA, except:
- S4 stock 6-port engine (just the core shortblock, intake manifolds, etc. are S5)
- Racing Beat collected header
- Magnaflow stainless steel offset 4x9-inch oval muffler (2.5 in-out)
- custom 2.5-inch pipe
- single Magnaflow polished stainless steel race-series muffler
- Pineapple Racing 6pi sleeve inserts
- K&N XStream high flow filter
- Apex'i SAFC-II
- Zeitronix ZT-2 Wideband

I have a Megasquirt EMS that i've been meaning to put in when i get the time to replace the stock ECU and SAFC, but i don't think it will make too much difference.

 

well, I asked because we didn't dyno past 150 and my NA has slightly more mods that yours so I think I could squeeze a couple of extra horsies. Awesome dyno results BTW, did you do your own tuning or did someone help you out?

 

thanks, i'm definitely happy with the result. yeah a good condition NA with similar mods, good maintenance and tuning should be around the same power level.

i tuned it myself. the SAFC is fairly simple to tune.
i will have a harder time with the Megasquirt.

 

good luck and go do a 1/4 mile run to see how fast 154rwhp is at the 1/4.

 

probably not that fast, haha.
my car is more of a autocross/road course car. i don't see myself going to the drag strip anytime soon.

 

Advance the timing!

I know someone who's done the same thing as you basically that made 172 whp, stock ports, then again i dont know if the S4 has larger or smaller ports than the S5 and i dont know if you have S4 rotors.

 

yeah i didn't have time to really play around with the timing.

172whp is quite high for a stockport engine, what modifications were done? i have not heard of that high for a stockport NA.
both series have the same port area.
my engine is internally S4 (rotors, etc.). the S5 has slightly higher compression and less rotating mass, and usually is thought to have a bit more power just based on that, but from my results i doubt it's a big difference.
the S4 is rated at 146hp at the engine, and i am dynoing at 154whp. i think the S5 intake is the biggest factor for the increased output for S5 vs S4.

i also dynoed on a Mustang dyno which supposedly usually reads lower, and more accurate, than the popular Dynojet dyno.

 

Here's a log of an SCCA ITS class car we did for a customer. Stock port, 6-port NA. Stock injection, stock computer. Mid 170s is pretty common for a properly tuned stock port engine. We're now using the Rtek to fatten up the bottom end. We're seeing 10 hp gains in the 4-6k rpm range and as much as 18 hp gains just past peak power. Any questions feel free to email us. ludwigmotorsports at inightbb.com

http://www.ludwigmotorsports.com/rx7/denton_dyno.jpg

 

Who told you to shoot for 13.0 AFR's?
The ideal "power" AFR is something like 12.5 - 12.8 or something like that.
Any reason why you tuned that lean?
Mileage???

With the dyno, you should've just keep adjusting eveything until you get best power.
You really need to stop looking at the AFR's...
I think if you added more fuel, the power would've kept climbing.

Even with that said, 155's on an MD is easily over 160's on a DynoJet, and that's pretty good!


-Ted

 

"Ideal" in a text book maybe but that's just not true at all in this case. Best power on a stock port NA engine is going to be in the 13.7 range or slightly leaner. On the car in the link I posted above we made power gains in the 14s but the EGTs were nearing 1800* and we backed it down to safe up the tune. That car is currently leading the Mid-Div ITS championship and we won the Cen-Div title in 05. Trust me when I say peak power is not found in the 12s.

 

about 13.0 just from word of mouth and what some other rotary NAs have been tuned to.
i didn't try going below 13.0 AFR on the dyno, but my 3rd and 4th run were about equal, and i added quite a bit more fuel on the 4th run.

now with that said, the reason i didn't go any richer on the dyno is because i knew on the street the car runs generally a little richer anyways compared to the dyno. data logging on the street has confirmed this, i am usually seeing high 12s at WOT. the car is running well and making good power so i will leave it.

 

Sorry to get this sidetracked...

What kinda induction / intake system is on this car?

The 12.7 - 12.8 AFR is the general consensus of "best power", but I agree that it is not a strict rule for all applications.
It's just a rule-of-thumb of sorts.

I've heard of racers claim "lean is mean" theory also...


-Ted

 

Hey Ludwig,

This dynosheet you posted, which kind of dyno is it done on?

 

Mustang.

 

Sweet ...

As for tuning, are there anything done to timing on that ITS class car?

 

CAS was set to 27* total advance at WOT @ 7000rpm. We now have a programmable ECU that is ITS legal that allows us to just dial up whatever timing and fuel we need. We're not making real big gains at peak HP over a car with an optimized fuel pressure regulator because the cars already been tweaked to give good numbers there. But we can make some nive 8-10hp gains below peak HP and some real nice 10-18hp gains just past peak HP. Contact me offline if you're interested.

 

i'm looking at this again and it seems that the VDI is opening too late. the little kick at 5500 feels cool in the car, but looking at the dyno chart opening about 500rpm sooner would be a lot better.
any ideas? this might be a good excuse to finally put the Megasquirt standalone i have into the car...