My turbo build: 1970 Mustang Grande

ForceFed70 · Jan 25, 2008

10secgoal said:
Looks REALLY good. Here the turbo whistle yet ?

Thanks!

It's hard to rev up the engine much because the tune is so far out, but yes I've been hearing that whistle... makes me giddy.

10secgoal · Jan 25, 2008

Amazing how much pumping loss is gone just by that little pressure in the inlet tube, huh.
Man, just realized I can't even spell ''hear'' correctly.

ForceFed70 · Jan 25, 2008

10secgoal said:
Amazing how much pumping loss is gone just by that little pressure in the inlet tube, huh.
Man, just realized I can't even spell ''hear'' correctly.

Yeah, I was a little surprised at how much the tune was out. But I also did a bunch of different stuff to the ECU (upgraded firmware, changed the injection scheme to "4 squirts alternating", switched to X-tau based acceleration enrichment, etc) so I suppose having to re-tune is to be expected.

As for the spelling... Bah, we're all a bunch of grease monkeys. So long as it's close enough to understand it's good enough for me.

wicked93gs · Jan 25, 2008

x-tau? is that MAP based? because if its not, it will never work very well with a boosted car, and how do you know the tune is so far out? as long as the constants are correct for a v8 with TBI(I only know what they should be for 4 cylinders so far) it should run fairly smooth, regardless of how far off your enrichments are, idle should be fairly smooth...also, revving it up in idle, the turbo wont boost anyway, you'll be lucky to hit 100KPA, so in theory you should be able to rev it up to 3000RPM or so at least as long as your tune is somewhere in the ballpark

65ShelbyClone · Jan 25, 2008

Extra! Extra! Read all about it!

http://www.megamanual.com/ms2/xtau.htm

The short description is that xtau time is proportional to MAP, but inversely proportional to RPM. It appears to take both into consideration.

ForceFed70 · Jan 26, 2008

wicked93gs said:
x-tau? is that MAP based? because if its not, it will never work very well with a boosted car, and how do you know the tune is so far out? as long as the constants are correct for a v8 with TBI(I only know what they should be for 4 cylinders so far) it should run fairly smooth, regardless of how far off your enrichments are, idle should be fairly smooth...also, revving it up in idle, the turbo wont boost anyway, you'll be lucky to hit 100KPA, so in theory you should be able to rev it up to 3000RPM or so at least as long as your tune is somewhere in the ballpark

A turbo acts as both an intake and exhaust restriction which in turn effects volumetric efficiency. So yes, needing to re-tune is quite common. I also mentioned I made a bunch of programming changes which will also effect the tune. The tune was close enough to get the car started, but needs a bunch of tweaking.

65shelbyclone already posted a link to the X-tau megasquirt info. It's a good spot to start learning about it. In short, X-tau does take the map signal into account but it's a completely different acceleration enrichment scheme that would take me too long to try and explain. Check out this video clip on a presentation about X-tau, it's 20 min long but does a good job of covering the basics.
http://video.google.com/videoplay?docid=-1671092540772647555&hl=en

ForceFed70 · Jan 26, 2008

Dbl post

wicked93gs · Jan 26, 2008

I have all my acceleration enrichments on the neon based on MAPdot, in fact, the car runs exclusively on MAPdot and currently doesnt use the TPS sensor at all(I have other uses I'll use that for eventually) I'd rather have my enrichments based exclusively on MAP simply because i dont care what RPM the engine is turning(I only care about the boost pressure going into the engine), the only RPM based tuning I do is in the VE tables, to me it just seems the safest way to go on a boosted car

ForceFed70 · Jan 26, 2008

wicked93gs said:
I have all my acceleration enrichments on the neon based on MAPdot, in fact, the car runs exclusively on MAPdot and currently doesnt use the TPS sensor at all(I have other uses I'll use that for eventually) I'd rather have my enrichments based exclusively on MAP simply because i dont care what RPM the engine is turning(I only care about the boost pressure going into the engine), the only RPM based tuning I do is in the VE tables, to me it just seems the safest way to go on a boosted car

You don't have a choice about RPM based tuning vs some other method if you are using a speed density ECU. X-tau isn't "RPM based" it takes multiple factors into account, RPM is just one of them. Seriously... watch that video, you'll learn why it's a better enrichment scheme.

There is more at work inside an engine than just manifold pressure. If you want the best tune, you'll look a little deeper into what's going on. Trying to ignore RPM is just silly as it has a big effect on what your acceleration enrichment should be.

wicked93gs · Jan 26, 2008

My tune its great, a good solid 12:1 AFR all the way while I'm under boost, 14.7:1 under cruise, I'll look into x-tau though...I havent used MS on a v-8 yet, but I plan to when I can finally work on the 66 again

stangme · Feb 7, 2008

Great project!!!
Looks like you have plenty of room on the drivers side for another turbo
your already building and tuning what I am planning.

BottleFed70 said:
Well, most of the work under the hood is now complete! And I started the car last weekend. I'm very happy with the outcome. Everything worked out great, it looks good, and everything looks like it "belongs".

Only work left to do under the hood is to put in a new ignition coil (and get rid of that yellow plug wire), and to put the hood on.

The next steps are to install boost and AFR guages, as well as re-vamp my existing guage panel. Then comes tuning.. I'll have to completely re-tune the megasquirt ECU due to all of the changed made.

Here's a pic of the new engine compartment:

My turbo build: 1970 Mustang Grande

ForceFed70

That's why they call it "dope"

10secgoal

Active Member

ForceFed70

That's why they call it "dope"

wicked93gs

65ShelbyClone

ForceFed70

That's why they call it "dope"

ForceFed70

That's why they call it "dope"

wicked93gs

ForceFed70

That's why they call it "dope"

wicked93gs

stangme

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