jantore

So had the car on the dyno again last night and got some interesting numbers.

The tuning is not finished as we ran out of time due to some config issues on the converted map we got.

Specs
13b-Rew Bridge Port 10.7 studs
Ligthed rotors and balanced. NRS 1 peice 3mm seals.
Garret GT4094R 1.06 AR
Autronic SM4, Autronic 500R, Crane Cames LX92 coils
Siemes Deka 850cc pri injectors, 4x Bosch 1300 secondary injectors.
HKS twin plate clutch

And alot of other mods, the same car my 4 rotor was in

Due to how the staging is, it's not completely smooth around when the 2nd and 3rd bank of injectors come on, but it's a matter of tuning. But overal it's getting smoother.

Boost is 1.3 bar wich is 19.11 psi or so.

Im impressed of the power in this turbo and torque



JT

jantore

Howard any thoughts to why the engine wants to go rich? At this power the af is about 10.5 on E85. At 11.2 it dropped 100rwhp.

JT

JZG

Nice numbers JT. By my calculation that's 531hp at the wheels.

Depending on how much overlap the bridgeporting has the engine may want to be a little richer when compared to stock or street porting. Particularly if turbine back pressure is high.

Oxy sensor placement can have an affect too - generally a sensor placed near the end of the exhaust system will read leaner than a sensor placed in the downpipe.

The other consideration of course is that the AFR meter may be reading lean in general.

At the end of the day, the engine tells you (via the dyno) how much fuel it wants.

JZG

What fuel pump/pumps are you using? What base fuel pressure do you know?
I've seen some unusual AFR's when certain types or injector max out.

Howard Coleman

iTrader: (6)

Hi Jan,

w a bridgeport your motor should just be awakening about where the dyno sheet ends...

you do have the right amount of fuel injector capacity for your turbo.

i have a 4094 and am very happy w it.

i am puzzled by the power drop off and don't think it is due to the AFR. i run between high tens and low 11s and it makes very little difference. what plugs are you running and what gap? can you get a non smoothed dyno sheet?

are you running 9 degrees IGL and around 10/11 split?

what is the dwell on your coils.... ooops you are running a CDI.

are you logging fuel pressure and if so what do you see up top? what is the indicated IDC?

hc

jantore

It's quite the big Bridge Port and alot of overlapping. Not running nice on idle under 1400 rpm. At 1450 where it is now, it's a nice brap brap brap BP idle

The dyno showed 560rwhp and 563nm, so it's calculated from that.

The O2 sensor on the dyno was in the tail pipe. And mine is in the bottom of the downpipe. Should have moved the dyno o2 sensor to the top of my downpipe. EGT was about 840 C so about 1544 farenheit.

The boost was dropping back at 7500 rpm. So might be backpressure. Will get a sensor for that. Also the boost controller is set at 1.15 bar boost as my spring is a tial 60mm 1 bar. But it won't go lower then 1.3 bar. So it could be the wg working that is lowering the boost. As wg dutycycle was just 15% or so.

jantore

Im running NGK R7420-10 plugs all around, standard gap on these. EGT was 840 celcius on both rotors. They where completely even. On E85 i was up to 15 degrees IGL and 7 split. Goes from 0 at 0 psi to -7 at full boost.

Fuel pressure is stable and rising and dropping with boost. IDC was about 80%

jantore

Dual Bosch 044 pumps. Base presure is 3 bar.

arghx

iTrader: (3)

Just continuing on that thought: The short answer is, you may be leaner in the combustion chamber than you think. Part of that is because of sensor placement, which is well understood. The other part is that overlap = scavenging and blowing fresh air right through the combustion chamber without it being burned.

Longer answer: Just give it whatever displayed AFR it seems to run best at. When you have boost and lots of overlap you get scavenging, afterburn in the exhaust, etc. That makes the exact AFR reading from the wideband difficult to trust no matter where you put it.

When I tune piston engines with variable valve timing on an engine dyno with load control, we run with an emissions analyzer. So what you can do is adjust your overlap, adjust your boost, and adjust your injection pulsewidth. What you'll find is that you can often have a wideband reading some AFR, but because of the scavenging and overlap it's deceiving you.

As you add more overlap and get more scavenging from boost, it makes your wideband in the exhaust read leaner because of the fresh unburned air diluting the mixture from the combustion chamber. Then you as the tuner add more injection pulsewidth to bring the wideband back to your intended value. However, when you look at the CO emissions (which correlate to overall enrichment), CO2 emissions (which correlate to in-cylinder AFR), and O2% (which correlate to mixing capability and scavenging) you'll get a better idea of whether you're rich or lean inside the combustion chamber.

jetlude

iTrader: (9)

You run that much IGL timing with E85 at 19psi? Is this in the peak torque area as well?

BLUE TII

iTrader: (9)

Howard any thoughts to why the engine wants to go rich? At this power the af is about 10.5 on E85. At 11.2 it dropped 100rwhp.

I think it is just because you have good ignition/coils you are not getting "rich" misfires like most people when you run the rich AFRs the rotary wants to make peak power at.

I have a crane Hi-6 and LX92 per leading coil and my streetport has always made the most power in the 10s AFRs (on many different and sometimes simultaneous wideband readings).

On my last turbo I had to flat line the wideband (only reads to 10:1AFRs) to keep the boost up with manifold burn and actually made more power on the top end that way.

I am still flatlined below 10:1AFRs on the new turbo from 5,000rpm to 7,000rpm, but I think the graph will smooth out a bit once I lean it to 10.5 to 11AFRs as this T4 1.05 is tighter than my old hacked up divergent AR stock housing.

BLUE TII

iTrader: (9)

Hi Jan,

w a bridgeport your motor should just be awakening about where the dyno sheet ends...

i am puzzled by the power drop off and don't think it is due to the AFR. i run between high tens and low 11s and it makes very little difference.

Just run the #s. He is maxing out the turbo by 7,200rpm because his bridge flows much more.

You are making 575 Dynojet @ 26psi and he is making 615 Dynapack @ 19psi.

Yes, I know it says "Flywheel hp" on the Dynapack- that is how you make them read like a Dynojet.

My set up dynoed within a one HP on Jefferson State's Dynojet and BlackTrax Dynojet with the same exact setup and boost, and within a month's time.

Yes, people saw the "Flywheel HP" on my Dynopack sheet and told me it would make less on a Dynojet as well

jantore

Hmmm

So hmmm maybe it just want's to be this rich. Only problem is that it fills up with E85 in the oil too fast with so much fuel, so il hafo look into taking off some fuel and seeing what we can do. But will be next time on the dyno.

Howard what is your ignition timing on E85 and 19-20 psi full throttle?

JT

Howard Coleman

iTrader: (6)

not necessarily optimised but no knock and good power



spilt is minus nine to IGL



AFRs mid to upper tens to low mid elevens.

howard

jantore

Hmmm that's very conservative ignition table for E85, il have a look at mine again and compare.

Thanks