how do i safely monitor my motor?

adomakin · adomakin's Garage

Im wondering what the best way of monitioring my 930 engine from detonation would be. im thinking along the lines of an egt gauge and an a/f gauge, what about a rev limiter? (seems like a sensible idea to me) what do you lot think? are these generally the most widely accepted means of keeping track of things? and what am i looking for? I know that reads like a pretty dumb question but ive never run a modified turbo before (especially one thats cost so much money!). does the egt spike real quick when an engine is close to detonation or will it creep up like an overheating engine? will the a/f gauge flick around or steadily go leaner? are there gauges that you can set to a required max temp/ min a/f ratio that give an audio alert? are the answers to these questions that clear cut? I doubt it but I thought id ask!

Thanks,

Andy

cnavarro · 05-19-2005, 11:11 AM

Head temperatures would also be a great one to monitor; I usually run one in conjunction with an a/f mix guage. MSD makes a knock sensor and guage that just records the knocking for relatively little money, although I have never used one myself personally except for the J&S Safeguard.

TimT · 05-19-2005, 03:29 PM

get an aftermarket knock sensor. The J&S is an impressive unit. You can mount a sensor on each cam tower quite easily.

cnavarro · 05-19-2005, 04:00 PM

How has the J&S worked for you then attached to the cam towers with the valvetrain noise?

350HP930 · 05-19-2005, 04:06 PM

+1 on the j&s

http://jandssafeguard.com

It would be better to mount the sensor to the top of the engine case to avoid valvetrain noise and have a better listening post for all the the cylinders.

I had a tweaked 930 that I tore down at 130K miles. Pistons and ringlands were still all in spec.

What is a better testamony to the effectiveness of closed loop knock control?

TimT · 05-19-2005, 05:05 PM

the tower that you mount the throttle lever to next to the oil breather is a good place to mount a sensor if you only choose to use one.

From what I gather from J&S their system only looks for knock X amount of degrees prior to each ignition event. Also Valvetrain noise is a different frequency than pre-ignition.. The transducers listen for a frequency that knock usually occurs at..

350HP930 · 05-19-2005, 05:11 PM

J&S is also cylinder specific. If one cylinder is more prone to knocking than another it only retards the timing for that cylinder.

cnavarro · 05-19-2005, 05:18 PM

Is it possible to use the safeguard with the CDI, as in a '70 911T?

350HP930 · 05-19-2005, 05:24 PM

Yep, it intercepts the inductive pickup or points trigger signal and passes on a delay trigger to the CDI.

cnavarro · 05-19-2005, 05:28 PM

Sweet! Who markets the Safeguard for the 911 guys?

350HP930 · 05-19-2005, 05:33 PM

You can buy a new one off their site for like $450.

Its too bad for you that I just sold my used one for half of that to a fellow pelican member a week or two ago.

cnavarro · 05-19-2005, 05:49 PM

That's what I thought that you were selling yours. Oh well. For that price, you'd think more people would be running them. Where exactly did you mount the sensor on the case?

350HP930 · 05-19-2005, 06:03 PM

Mine was mounted on the top of the case, between cylinder 2 and 5 on one of the case perimeter bolts.

kenikh · 05-19-2005, 06:10 PM

If it intercepts signals, it sounds like it could be used inline with EDIS on an MSnS/MS-II system. Why'd you sell it then?

350HP930 · 05-19-2005, 06:53 PM

The J&S intercepts one signal per spark event, the EDIS is six signals per timing event. For that reason I was not sure if it would work.

MSII has integrated knock control so that was my other reason to get rid of it.

adomakin · adomakin's Garage

hmm...knock sensors eh? I always assumed that because of the air cooled noiseyness of the 911 engine you couldn't successfully run a knock sensor. so you guys think that this is the best solution for detonation probs then? and running in closed loop i assume it just does it all for you? you put your foot down-it sorts things out if they get too hot, right? how about the other sensors i talked about then. are they worth having, just to monitor stuff?

Andy

350HP930 · 05-20-2005, 02:47 AM

A 911 is a noisier motor to an outside observer due to its lack of a waterjacket, but the sounds the motor makes on the inside are no different from a water cooled motor.

That being said the later model air cooled motors came with knock control from the factory to prove to the skeptics that it works.

adomakin · adomakin's Garage

cheers 350, are you running a/f monitor- egt-cht gauges?

Andy

beepbeep · 05-21-2005, 03:16 AM

I believe that best way of keeping and eye on your engine is by following means:

1. Start with conservative ignition map.
2. Carefully tune ECU to prevent lean conditions @ wot or high load.
3. Tweak the ignition untill knock occurs, than back off to gain margins.

So I would start with wideband O2 sensor and EGT probe to begin with. Innovative LM1 with AuxBox is a good start. It can also provide simulated narrow-band output for ECU that cannot accept WBO2 sensor.

As for installing aftermaket knock-sensor I wold leave that unaswered. Frankly, your engine should never be able to knock. If it does, you did something wrong. Also, those acoustic pickup electronics must me tuned to specific motor. I'm quite sceptic that "one size fits all" can provide anything else but basic knock indication.

With other words, these ae the factors that influence longevity of the engine:

- Twin plugs
- Moderate boost
- Good cooling
- AFR's in check (14.5 when cruising, 12.8 at WOT)
- Not too advanced ignition curve

EGT is also good to have but it's usually a function of boost and AFR.

So I suggest Innovative LM1 with AuxBox to begin with. When engine is up and running, you can fiddle with knock detection circuitry etc. when you stat playing with the bost.

adomakin · adomakin's Garage

cheers Goran, makes sense. what are you up to?

Andy