I'm installing a BS3 ecu for the 502 in my '69 RS/SS. In my previous car, I had a wideband AFR gauge that came with its own sensor, but since I'll be using dual widebands with the BS3, I'd have to find a gauge that I could connect in parallel with one of the BS3 sensors.

I was thinking of using a Pyrometer gauge instead of an AFR gauge. The turbo books I've read indicate that a pyrometer is more useful than air fuel ratio, but I'm not sure how to read one.. ie: how hot is too hot, etc?

During tuning, etc, I'll have a laptop, so I'm thinking more of something to keep an eye on down the track.

Does anyone have experience with pyrometers, and opinions on their usefulness?

Thanks,
Dave

 

Exhaust temperature is highest @ stoich. It falls off from either side of that. I don't find it useful for tuning, it is good however for giving you an idea of air/fuel distribution among cylinders provided you ran one for each hole, such as on an engine dyno. They're used on turbocharged diesel trucks to give an idea of the heat load being put into the system and allow the operator to make some kind of decision based on that.
A wide band is a great tuning tool and it will allow you to determine the most effective AFR at each point in the load map so you may duplicate the setup later on. It will also give you feedback on your ignition system and clue you in to any exhaust leaks that may develop on your boosted engine. If pre turbo installation is possible you might also be able to see idividual cylinder AFR. Because of heat and pressure pre turbo installation is not recommended however.

 

I was just faced with this very same issue. I had just about settled on a pyrometer when the local engine shop melted 6 pistons in a Whipple 3300 blown 502, at an EGT of only 1200 deg F. They normally tune NA engines to 1300 deg F. Another thing to consider is that retarding the timing will increase EGT, making it look unsafe, while directionally making the engine safer.

I think the best combination is a knock sensor and wideband, however, I've melted a piston with zero knock also so I question the knock sensors effectiveness.

 

I find an EGT gauge useful for tuning and easy to keep an eye on while part throttle driving. What temp to watch for will vary with engine set up, and I have gotten used to what to see on mine while tuning. I have seen the consensus to say 1500-1600+ is where you want to watch out for, and like mike said a low EGT can indicate problems too with detonation and/or incorrect timing.

 

You are assuming (and you shouldn't assume anything) not just equal fuel distribution, but 100% equal air distribution of the manifold as well. Without individual O2 sensors for @ cylinder along with balanced injectors, you will not be able to comfirm that. It is necessary to reduce the number of variables/unknowns to one.

It will also give you feedback on your ignition system and clue you in to any exhaust leaks that may develop on your boosted engine. If pre turbo installation is possible you might also be able to see idividual cylinder AFR. Because of heat and pressure pre turbo installation is not recommended however.

May I add that use of the word 'might' would apply if using a particular brand of WB controller? Not all are engineered equal.

Use of EGT devices is not useful on it's own for tuning, as it does not account for other variables. The best it can be used for is as a supplemental tuning aid.

Was the root cause of the piston destruction heat from a lean AFR or from ignition induced detonation? Was the KS a cheap OEM product? I question their effectiveness at higher RPM.

 

Well I tried to be clear on air/fuel distribution, I sorry if I wasn't clear and you felt I was assuming something.
You are correct in that the features I mentioned pertain to the Innovate line of wideband systems. Others may be just as fast and offer real time cylinder event monitoring, I just dunno.
I am pretty sure though that my post was clear in the spirit of the question posed, at least I hope so, and I think you're being a bit picky. : )

 

Yes.

 

Funny guy. Tough correcting the problem when you don't know the cause, isn't it?

 

Don't count on it.

... I think you're being a bit picky.

In this case attention is in the details. Unfortunately, if variables are not isolated, they go from something that can be determined or solved to sometime that remains unknown. If you consider that being 'picky', then I'm guilty. BTW, Innovate is now offering formal tuning classes. Those classes would reinforce what I stated in this thread and allow an individual to better understand where I am coming from. You'd then realize I wasn't being 'picky' but merely following a logical and methodical line of reasoning.

 

Are you serious Gary? Innovate has a great product and the forum is fun but most of us participating are already successful tuners in our own right. That's why we enjoy our affordable widebands.

Each to our own, and please try to remember to have fun.

 

Weeeell. . . when your Methanol pump fails, you suddenly have too much timing AND not enough fuel. So, to answer your question again, YES, the piston destruction was caused by lean AFR AND from ignition induced detonation.