NC with Cosworth making only 150 hp????

[jboemler]

The cams were indeed different (AT/MT) in the earlier cars, and I wouldn't be suprised if they are in the NC as well. I don't have any solid info on that, though.

[fredmuggs]

The cams were indeed different (AT/MT) in the earlier cars, and I wouldn't be suprised if they are in the NC as well. I don't have any solid info on that, though.

Thanks for the response:

I just checked with the local Mazda parts guy and he says, according to his parts lists, the cams are the same for the NC AT and MT motors. I guess Mazda probably did more engineering on their engines than Ford did on the NC motor.

Ok, to date:

The blower makes 8lbs boost, measured at the pressure port in front of the bypass. There's no way to measure closer to the head.
Two shops and I have looked for leaks and found nothing and the car shows no symptoms of leaks
I have disconnected the vacuum feed for the bypass control, leaving the bypass closed, and that made no difference
It's not a blocked exhaust
It's not a blocked intake path or filter
Brian swears by the calibrator and I'm sure the tune is loaded
It's not the cams
It's not the compression

Anybody got a brainstorm before I start getting my tools together to pull the blower?

Thanks,
Fred

[JohnB082]

Just a thought, but is it possible that the bypass, even with the vacuum control disengaged, is stuck partially opened?

Thanks,

John B

[fredmuggs]

Just a thought, but is it possible that the bypass, even with the vacuum control disengaged, is stuck partially opened?

Thanks,

John B

Hi, John:

I wondered about that issue. As I understand, the bypass valve opens to bleed boost pressure when engine vacuum is high: part throttle, cruise and so forth. It must close and remain closed when there is no vacuum, or the vacuum actuator is disconnected, routing any boost pressure to the intake manifold only when it would be needed to increase performance.

In about my twentieth email to Cosworth, they finally offered that I could pull the vacuum line as a test of bypass actuator and linkage function, but they didn't suggest or even mention possible problems with the internals of the bypass valve which would prevent it from sealing or remaining shut when it was supposed to. That's could be because, with respect to this particular kit, Cosworth may not have any idea how it works.

Turns out, the supercharger is a Magnuson kit, which Cosworth distributed for a while and seems to be in the process of discontinuing AGAIN! That's probably why getting tech info from Cosworth on what I can do to test or examine the function of the bypass valve has seemed like pulling teeth. They probably don't know how the thing works -- but didn't want to admit they don't know enough to support the kit.

Brian contacted Magnuson to see if they offer any support. We'll see if they do. I may have wound up with something nobody wants to support. Think I'll pull the Cosworth decal off the car when I pull the SC.

Thanks for the interest,
Fred

[morrisg]

Ok, here's another total shot in the dark. You're pretty sure its making 8 lbs boost and that's getting to the cylinders and out the exhaust without excessive restrictions. The other side of making more power is the extra fuel that's supposed to be injected into the cylinders and the spark to ignite the mixture. I'll avoid any speculation on missing sparks as you would probably notice uneven firing just by the sound of the exhaust, though it is a quick check to remove each plug wire individually to see if it makes a difference in the engine sound or exhaust, just to make sure all the coils are working well. Of course, a new set of Denso irridium plugs might not be a bad investment for the future as they tend to fire under more extreme air/fuel ratios than normal plugs.

So, maybe the duty cycle of the injectors on the car is getting maxed out and not flowing enough fuel to keep up with the extra air? Air/fuel ratio going very lean would be a clue to this condition. I'd check fuel pressure at the injector rail to make sure it doesn't drop off or flutter under acceleration, too. Easy to check and if it's solid it eliminates fuel pump and filter problems.

Since this is a used vehicle to you and it came with a cracked cat, I'd check to make sure you have the correct injectors on the car as well. Maybe the previous owner put some other injectors in and got the wrong ones back in the car after all the goodies were removed? Perhaps the ECU doesn't actuate these injectors as well? Also, Mazda sometimes has problems with the wiring at the injector or spark plug coil connectors as vibration tends to take a toll on the wires and they can be intermittent.

Like I said, total shot in the dark.

[elloco54]

Look again at your dyno sheet. that saw tooth graph is being caused by some sort of restriction. You have 3 choices 1 the bypass valve 2 the exhaust after your new header 3 something left in the blower. If you disconnect the exhaust at the header and tie it to the side. Make a quick (and loud) run if you still have no power you need to pull the blower and look for a problem there. Check the blower seals ,look for packing stuck in the runners, you should also be able to verify the operation of the bypass with a vacuum pump.

[fredmuggs]

Ok, here's another total shot in the dark. You're pretty sure its making 8 lbs boost and that's getting to the cylinders and out the exhaust without excessive restrictions. The other side of making more power is the extra fuel that's supposed to be injected into the cylinders and the spark to ignite the mixture. I'll avoid any speculation on missing sparks as you would probably notice uneven firing just by the sound of the exhaust, though it is a quick check to remove each plug wire individually to see if it makes a difference in the engine sound or exhaust, just to make sure all the coils are working well. Of course, a new set of Denso irridium plugs might not be a bad investment for the future as they tend to fire under more extreme air/fuel ratios than normal plugs.

So, maybe the duty cycle of the injectors on the car is getting maxed out and not flowing enough fuel to keep up with the extra air? Air/fuel ratio going very lean would be a clue to this condition. I'd check fuel pressure at the injector rail to make sure it doesn't drop off or flutter under acceleration, too. Easy to check and if it's solid it eliminates fuel pump and filter problems.

Since this is a used vehicle to you and it came with a cracked cat, I'd check to make sure you have the correct injectors on the car as well. Maybe the previous owner put some other injectors in and got the wrong ones back in the car after all the goodies were removed? Perhaps the ECU doesn't actuate these injectors as well? Also, Mazda sometimes has problems with the wiring at the injector or spark plug coil connectors as vibration tends to take a toll on the wires and they can be intermittent.

Like I said, total shot in the dark.

Hi, morrisg:

Excellent thoughts. The longer I chase the missing horse power, the more I learn about how the parts works together. And some really knowledgeable folks have been chipping in.

Fuel -- The injectors are new, came with the kit and supposedly higher flow than stock to support higher fuel requirements. I have not checked the fuel pressure under load. However, the Air Fuel Ratio (AFR) has been right on, responsive to the calibrators changes and remained exactly where he set it during load conditions.

Ignition -- One of the early changes I made when I realized power was way down was suggested by the calibrator who ran the second dyno and confirmed by Mike the calibrator at Moto-East. I installed a new set of NGK plugs, one heat range colder than stock and gapped at only .030" Colder was to accommodate higher chamber temps in a better fueled/aspirated motor. The relatively narrow gap was to accommodate the possibility that a denser air/fuel mixture in the force fed chambers might stifle the spark under load (The jargon is "blow out the spark."). I have not followed the directions in the '07 Shop Manual for testing the coil on plug (cop) NC ignition configuration.

Changing the plugs was the only change between dyno run 1 and dyno run 2. I believe I did pick up 8 HP between those runs. At least some of that was probably from the plugs. The COP ignition will fire a wet cigar. But the original plugs did look pretty sad when they came out of the motor.

Yesterday, I finally got someone to discuss the "static" within the dyno curves. I have to wonder if that is not a symptom of either the ECU throttling back for some reason or responding to some other problem that I have not yet recognized. I've emailed Moto Mike, the principal calibrator, to see if the logged throttle position data would actually show the throttle plate closing down while the pedal position is still wide open. Moto Mike says the "engine load" is off by around 15%. Maybe the ECU is cutting power 15%. I'd never know unless we find it in the data.

Thanks very much for your insights. I've wanted to learn more about logging and electronic engine calibration. I'm getting the crash course. Think I'll dig out the multimeter and check those coils. I can also try to fabricate aa fuel pressure gauge. Seems like there's a fuel pressure test port at the fuel rail. No excuse for not touching all the bases.
Fred

[fredmuggs]

Look again at your dyno sheet. that saw tooth graph is being caused by some sort of restriction. You have 3 choices 1 the bypass valve 2 the exhaust after your new header 3 something left in the blower. If you disconnect the exhaust at the header and tie it to the side. Make a quick (and loud) run if you still have no power you need to pull the blower and look for a problem there. Check the blower seals ,look for packing stuck in the runners, you should also be able to verify the operation of the bypass with a vacuum pump.

Hi, elloco54:

I, too, really believe what you call a "sawtooth" in the dyno curve is a solid symptom.

I'll be losing the rear cat and resonator for a few days next week. Not so much worried about the new muffler from Brian.

Magnasun says they believe the internals of the bypass to be in good shape. Makes sense, since boost comes in with increased throttle. I have verified the extrenal components are not blocked or damaged and the actuator works fine. But, the next time I go to the dyno, I will disconnect the bypass actuator during the runs to see if the "static" still appears in the HP and torque curves. May the bypass is somehow blowing open. Calibrator says engine air flow is down by something like 15 percent. Just don't yet know WHY it's down.

I checked very thoroughly for foreign objects in the blower and runners during the install. If I wind up pulling the blower, I'm adding a pressure port in one of the runners.

Thanks for your interest,
Fred.

[fredmuggs]

Buenos dias from the Eastern Time Zone:

Brian:
I've been counting all the "legitimate holes" in the intake and SC. There's the: throttle body, PCV, brake vacuum, evap line, boost sensor port, and EGR. Beyond those, boost (in fact all the air in the intake system) is supposed to go to the head.

Seems like I should be able to block the throttlebody and other lines and do a sort of leakdown test for leaks at the EGR and head. I could pressurize the entire intake system by pumping air into, say, the PCV port on the intake tube.

Wha-da-ya-think?

Thanks,
Fred

[morrisg]

How about another shot in the dark? The EGR is exposed to the boost? Ok, it's supposed to flow exhaust gas back into the intake, but what if it's leaking boost inlet air into the exhaust? Can you block it off or use a clamp to close off the hose to test this? You should be able to feel 15% more power so you might not need a dyno for this test.