LS1 RX7 build

[toplessFC3Sman]

Ha, that sounds like a fun winter project! For a V8 in an FC, where do you think you'll have room to mount the turbo so that it can be fed by both banks? Will it fit between the radiator and the accessory drive? Are equal-length headers a possibility to package?

[ITSWILL]

One bank will just have a longer run to the turbo, since the turbo will likely go behind the passenger headlight.  I'm not really all that concerned about it with the number of exhaust pulses from a V8. Should I be?

[toplessFC3Sman]

The turbo should be fine, it'll just create a little bit different exhaust residual tuning for one bank vs the other, so at some engine speeds the left bank (or the hottest cyl in that bank) will be richer with hotter exhaust & more prone to knock, and that will shift to the other bank at some speeds. If you're not tuning it to the ragged edge, overall it shouldn't matter much - you'll just notice different cyls getting hot at different speeds.

[ITSWILL]

I wish I could have 10 egts and 10 lambdas like at work.

[toplessFC3Sman]

Yea, me too! it would make things a lot easier, although trying to implement an in-cyl pressure transducer on a rotary would be tough. You'd need 3 per rotor, and would have to stitch together the traces from each based on rotor position. I've thought about it a few times, but I'm not sure I want to turn a fun hobby into a serious experiment

[ITSWILL]

Oops...

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On the left is the replacement, center is the good one from my diff, right is busted (notice the replacement has a different spline root without a filet)
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[murz]

That's crazy, you know i wonder if that replacement is stronger like that?

[toplessFC3Sman]

Ouch!  I know that the S5 turbo diffs had different lengths than the S4 (and a difference left vs right), but wasn't aware that there were differences with the S4 shafts

[ITSWILL]

I think some of you know that I have a wide band AFR display integrated into my idiot cluster where the clock used to be.  Now that I'm preparing to do a turbo I started looking for a similar gauge for boost/vacuum that could be integrated like stock. Unfortunately the company I bought the AFR gauge from does not make a similar gauge for boost and had no interest when I asked them about it.

So I decided to just make my own.  At the moment I have it all working on a proto board.  The heart of the gauge is an Arduino UNO.  I have the Arduino programmed to take in a 0 to 5 V signal like a boost pressure sensor creates and output a -10.0 to 30.0 reading on a 4 digit 7 segment display.

The plan will be to locate it in the lower portion of the Tach so it is front and center

I ordered a more compact Arduino with the same processing capability that I will ultimately be using but I am wondering what you guys thing of the 7 segment display.

Do you think having 1 decimal point is good or not needed?  Do you think vacuum should be shown in inches of mercury or just - PSI?  These items would determine the number of segments I need for the display, could be as little as 2 or as many as 4.

In the future the Arduino would be able to use a PWM output to control a boost solenoid with boost pressure based closed loop control.

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[toplessFC3Sman]

Thats really neat! But PSI or in-Hg? Really? I thought you were an engineer! kPa or bar all the way!

[ITSWILL]

I thought about KPA.  I may still go that way.  That would only need a 3 digit display.

[toplessFC3Sman]

If you went with bar, you'd be OK with 2 digits (and one decimal point) if you really want to minimize it, although you'd lose some precision when throttled (which could be useful if you're tuning it)

[fidelity101]

that is really clever! should be fine with 1 decimal point IMHO

[toplessFC3Sman]

I may be coming to you with some questions on the arduino and using the 7-segment display; I just got a starter kit and hope to do something similar for sensing additional temperatures and switching the e-fan and water-to-air IC system... free up some IO on the megasquirt for getting individual exh T measurements. Speaking of that, I need to start writing up some of these cooling changes. Maybe over Christmas break, I hope to get a day or two of wrenching in.

[ITSWILL]

Just let me know, I'm on to rev 2 of the boost gauge. I have the whole assembly down to about 1.25" x .75".