New DYNO pulls

[karmavore]

Boost is all over the place and I'm worried about the A/F. Thoughts?

[Jonathan]

Yeah dont seem right at all - what chip, turbine etc ? (cant remember what you done to it now)

Lots of power but it's all over the shop - 20psi is 1.37bar boost - std ECU cant read that so anything past 16psi is playing with the A:F no doubt

20-21 psi is dangerous levels ? ergo 330BHP

[karmavore]

I'm embarrassed to say I'm not sure on either account, Jon

John Welch explained it all to me but I forgot. It's a new version.

[Rich H]

Surely although it's off it's to the safe side ie too rich.

At least it's not going to melt down, but it will drink heavily!

[f1karting]

Mixtures seem OK (ie:<12.5 is best IMO) I am not familiar with the OE ECU.. perhaps with the ECU max read at 16psi, once you get over 16psi boost, the ecu delivers fueling for 16psi and not 20 .. perhaps thats why over 16psi, you go lean?? just a thought.

Other reasons for being all-over-the-map could be the quality of signals from the sensors to the ECU.. make sure your electrical contacts and grounds are VERY good.

[Artie]

Lucas,

Your AFR's should be no higher than 12.3 with that kind of boost. You hit 13.87 at one point at 20+ Psi. You only made 330HP cuz I bet the ecm is pulling crazy amounts of timing! I know you have a fuel system fit for a king! I am currently working on a bypass feed 12V source and relay for the Sport 300 pump I have installed. In 3rd gen RX7's the fuel pump runs great until about 16 psi then starts to lose pressure because the ECM starts divying up power to other things like ignition to keep the mixture burning. I'm not sure this is the issue, but you are not getting enough fuel delivered! I am frantically trying to figure out a way to crack into the lotus code to be able to tune these cars the correct way! There is so much more power to be had with this engine and it's being locked inside that box! Anyway, check your base pressure, which I am sure you have before, but if you can buy a vacuum pump and a cheapo boost gauge, start running the engine with the fuel gauge on the fuel rail schrader valve, then hook up a vacuum hose to the exhaust port on the vacuum pump and run it to the FPR. U can T in the boost gauge(I got one from autozone for like $35 and use it for testing the various turbo cars I work on periodically) into that line so you can see how much pressure you are applying to the FPR. for each PSI you should see an equivelant psi of fuel pressure. Usually you can only get about 5 to 8 psi from a vacuum pump outlet port but if the FPR isn't raising pressure accordingly then you aren't getting fuel delivered appropriately. Also, what sized secondaries are you running? Primaries? Have you checked to see that the secondaries are coming online? I had an issue a while back where the resistor had shot craps on me and my secondaries weren't kicking in! YIKES!

Also, Another great reason to use a good quality electronic boost controller! My boost will vary on the dyno maybe .5psi from start to finish of the pull, unless my clutch slips or the tires spin.....Less load means less exhaust energy for the turbo, very common on light cars, especially on the street or at the drag strip where tirespin is common!

Rich,

I'm afraid you have the AFR values backwards my friend. The higher the AFR value, the leaner the mixture. The more O2 in the mixture, the more volatile the mixture becomes. Think of it like a can of gasoline! If you throw a match onto the open can of gasoline, it most likely will just catch fire.....Now, conversely, if you have very little gasoline in the can, but lots of vapor and oxygen and throw on that same match.....BOOM!!! You will get a much more violent explosion! Rich values are 11.XX and lower. 12.3 for this hemispherical combustion chamber is ideal, lots of propogation and good burn characteristics. too rich like 11.5 or lower and you risk washing the cylinder walls of their oils and lubrication! But you can run rich all day long, but can run lean once and blow the head gasket or worse!

Edited January 27, 2011 by Artie

[karmavore]

Thanks for the long reply, Artie. I asked John Welch to help me diagnose the issue from some freescan logs and his theory is along the same line as yours. He suggested a new alternator and maybe a battery.

The new alternator and boost controller are being installed now. I'll let you know the results!

[Artie]

Lucas,

Sounds great, keep us posted. Batt voltage is paramount as we push the ignition system harder to burn more boost/fuel/air. Usually at the expense of battery voltage to the ecm/fuel pump. Very common on high performance turbo cars as you push the system to it's maximum. What boost controller did you decide to go with ? Have you considered installing a wideband in the car so you can monitor the afr's realtime? Just a thought. I have one in my RX7 and the Esprit. If the afr's go past 12.5 I get out of it and adjust. At least on the RX7 I can tune in more fuel at a given rpm but the Esprit just turn the boost back some on the controller. I'll be interested to see what your power looks like when you get it sorted out! I'll buy the popcorn! Video?

Artie

[karmavore]

Artie,

For the boost controller I went with this: Tru Boost

It's not quite as sophisticated as I might like, but that fact that it will replace the factory boost gauge and not take up additional room is a huge bonus to me.

Re: A/F meter, I was considering one, but I honestly did feel like I could reference it close enough for it to be effective. I'm hoping once I get it dialed in on the dyno it won't be an issue. We'll see.

Re: Horsepower, The dyno above was a Mustang measure at the hub, not at the wheels. 330 seems pretty health to me!

I've also been toying with Water injection using the AEM system. It seems like it's well designed. I just don't know if I want to push the engine that far.

[Artie]

Yes, that's great on a mustang dyno, usually about 8% lower than a dynojet. Ill have to look into that controller. Sometimes sinpler is better in my experience

[Tony94S4]

dangerous afr on peak torque,

try to let off on the dyno next time u c those mixtures,

hope you figure the problem out

[karmavore]

New pulls from yesterday with new alternator and AEM Tru Boost. I'm very pleased with the boost curve, and the fuel is better too. Now I want to clean up the dips in power and torque @4500. Any thoughts?

This is the BC's "B" setting. We were striving for 15PSI at redline.

This is the BC's "A" setting. We were striving for 13PSI at redline.

[Artie]

Definitely looks better Lucas. The power seems reasonable for slightly more than 1 bar. You may try a slightly hotter spark plug to give you a little more burn for the dip in torque. The Afr is a bit lean on the 15psi run, maybe try a bit of octane booster next time, Lucas(what a coincidence) brand booster seems to work best in my experience, but I always use 2 bottles since octane boosts points in the tenths position. Ie, if the octane booster claims a 6-8 point increase and you fill up with 92 then you will only see about 92.6 to 92.8! Not 100 as mislead by most labels. Also, how do you like the controller? Is it holding the boost steady or does it still drop off?

Artie

[karmavore]

Thanks a million Artie, as always.

Boost cure was fairly flat on the 13PSI run, but spiked and tapered more dramatically on the 15PSI run. It's odd to me that this would occur. The AEM runs at a constant duty cycle (above the waste gate spring pressure) so, if anything, I'd expect the boost to climb with REVs, not fall. Anyway... but yeah, I love the control and consistency the controller allows.

I might up my secondary injectors, add meth, or both. I'll also give the octane boost a try!

[Artie]

Well, as you increase boost, the wastegate door is kept closed longer so the controller was holding the door closed then allowing it to open slightly and keeps adjusting open/closed to hold boost. It may be easier at a lower setting to just "crack" open the wastegate a little bit and "hold" it there to maintain 13 whereas 15 is closer to the max efficiency of the compressor/exducer so therefore having to adjust more. Just a theory but seems plausible

Artie