TR2/3/3A TR3untapped power from SU needles re Oxygen Sensor

[TR3driver]

Re: TR3untapped power from SU needles re Oxygen Se

Though I s'pose one could be as accurate by just setting a finger athwart the space between piston and block at near TDC and feel the piston hit the full height.

If you can do that while driving down the road and accelerating; you've got a lot more guts than I have !

 

[DrEntropy]

Re: TR3untapped power from SU needles re Oxygen Se

Stickin' a sendin' unit in there wouldn't be advisable either, would it? That'd mean drillin' a hole in the piston chambers or finding some magic way to NOT impede the piston travel or flow characteristics yet ATTACH the sender arm to it...

I was speculatin' on a way to find ENGINE TDC with head off, engine on a stand... segue. My bad, huh? Should I go stand inna corner now? /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

 

[martx-5]

Re: TR3untapped power from SU needles re Oxygen Se

Here's some really good info on using O2 sensors and Air Fuel Ratio gauges to tune SU carbs. And that means finding the right needles, not just playing around with jet settings and Unisyns. This is the plan I'll be following once I'm up and running.

 

[BryanC]

Re: TR3untapped power from SU needles re Oxygen Se

Are you planning any sort of check to see if you've made an improvement in power or acceleration? If not a real dyno, you could use StreetDyno or HomeDyno or equivalent to measure how the car accelerates to see how much of an improvement you've made.


Bryan

 

[martx-5]

Re: TR3untapped power from SU needles re Oxygen Se

Are you planning any sort of check to see if you've made an improvement in power or acceleration? If not a real dyno, you could use StreetDyno or HomeDyno or equivalent to measure how the car accelerates to see how much of an improvement you've made.


Bryan

This is a very interesting question, and one that I hadn't given much thought to. If my initial AFR's are way off, getting them in balance will produce a noticable result in the seat of the pants dyno. If they are close initially, and are fine tuned to the optimum AFR, then the effect will not be as noticable. But, that's OK. After you've done all the other things neccessary to get power from the engine, the carb tuning is the frosting on the cake. Get that right, and the engine will just come alive and be very responsive. Your engine will thank you in the long run also. Running too rich or too lean is not good for longevity.

A little story here. I have a '92 Miata that is supercharged, and uses an auxillary fuel pressure regulator (AFPR) to raise the rail pressure on the injectors to supply more fuel when under boost. For every pound of boost, it adds six pounds of fuel pressure to the rail. My supercharger puts out 6 psi, so I need an additional 36 psi of fuel pressure over the basic 50 psi. That's about 85-90 psi that I need at full boost. One day I noticed that my AFR's were dropping into the 13:1 ratio while under full boost. I took fuel pressure readings, and only had 80 psi available from the pump. New pump, fuel pressures up, and the AFR's went back to 12:1. I couldn't feel any difference, but if I continued to run lean, I'd probably put holes in the pistons.

Like I said, all of this might net some great improvements, or maybe you won't notice the difference. But, running with the proper AFR's, at least you know your engine will be happy, and you will be getting the most out of it.

The nice thing about using O2 sensors and AFR gauges, is that there is NO GUESSWORK.