All interesting stuff and fun to read regardless of universal results. I have removed the smog pump, AC compressor, and updated the cat with a 3" single exhaust but don't have any dyno info or gains to talk about. I am very curious about is the air pump's function concerning the plenum's trick powerband manipulation design.
From reading here: M5 engine is seems that the air pump charges the pressurized air necessary to control the resonance flap. With it removed, the engine would feel pretty lethargic until ~3,500 rpm then drop off again at 6,700. This is pretty much how my engine feels and I have removed the smog pump. Therefore I assume the air pump and the smog pump the same item and I should put it back. Am I off somewhere?
The secondary air injection system has nothing to do with the variable resonance setup of the plenum. In fact the only thing they share is a common EM valve part number to actuate via vacuum not pressurized air by the pump, the secondary air injection valve is mounted under the plenum on the black rail. Youre right that without the variable resonance the car wouldnt have as much torque at low rpms and would lose some higher up, have you checked the actuation of your variable resonance system?
Excellent responses, thanks for the info. I am glad because that smog pump weighs a TON and I didn't want to put it back in! I know my flap does the self check twice upon start up 100% of the time but haven't yet confirmed if it opens again at WOT or whenever its supposed to do its' thing.
Remove the hood, and drive without it. Then you can see if the flap is moving.
Thanks, I will either do this or glob test after the start up cycle check. I don't have any loose vacuum lines and believe my resonance system works correctly, just turns ballistic around 4k. Enough about me though, back to performance gain debate!
I can say that putting Mark Dsylva's (EAT) 91oct s38b36 chip in as a stand alone change immediately offered noticeably more power and seems to have spread the powerband out a little more. Call lme crazy but it also smoothed out my idle. I have been a long time user and believe in his chips where as I do not like Dinan's or Turners (from e30 experience anyway). I wish he'd make a 93oct version.
I applaud OPs attempts at establishing a baseline and then making a modification and remeasuring.
I would have been more interested in his findings if the story had gone differently.
Ie, after the first Dyno run, he should have realized from the AFR that his engine was not running properly. This means that something in the system, whether it was TPS, air meter, IAT, O2 sensors, coolant sensors, vacuum leaks (whatever) is suspect, and in fact can not be relied on. Essentially he did not have a stock car as claimed, he had a broken car, without a diagnosis. Until that is fixed, I don't see how any reliability or reproduction of baseline can be counted on. He may well have components that are transiently working, and then not working. This issue to me pretty much negates any findings he's made, he's got to fix his car first and take out the variable of a broken and hence unreliable system.
Is there ANYone (other than OP maybe) that believes his baseline run reflects expected AFR for an S38 with a healthy engine management system with all components working properly?
A second consideration is that even in the absence of a reliable engine management system, the actual condition of air pump and AC compressor are not necessarily representative of properly functioning devices. It may be that they are damaged and did in fact present a much higher than common parasitic drag to the system. In that case, OP's findings might be applicable only to his car, or people with similarly broken/worn or damaged air pumps and compressors.
I'd love to see this energetic new member fix his car, get a baseline that represents an S38 running properly, show a dyno run where the AFR is where it should be to confirm all is well with his engine management, and THEN cut the belt to see the difference. On the same day, after the cars fluids are properly warmed up in gearbox, diff etc....
You can't have it both ways, if OP wants to trust his first Dyno shop of choice, then the message from their AFR should have been "go fix your car"
Ie, their WB is probably accurate, his car is not functioning properly, or in my mind reliably.
The main benefit is an octane boost when required (if it's an on demand system) in countries where high octane fuel is difficult to get (like Indonesia) but performance gains are available on 95 and 98 RON octane if you're running high compression (11:1 +) and you can run more ignition timing advance. A nice bonus is it does a great job of decarbonising the cylinders apparently.
Can a knock sensor be added to the E34 M5's ECU and can the chip be programmed to process the knock sensor inputs ?