www.RX7fb.com

Yeah I didn't wanna scare myself with compression numbers while it was working fine

It's a shame I never got round to getting a dyno graph for the stock fuelling set-up. I can say the acceleration was a dead heat with my friends aw11 mr2, and they are meant to be ~120hp and his is in reasonable condition so I can't be that down on power.

Life!

http://www.youtube.com/watch?v=nP4Q-j4tPgw

The map really really is a long way out, but the worst of it is over. The fact that it starts means I can start tuning the map with live readouts of how it changing AFR and alike, which makes life much easier.

Plan is to get her out of the garden saturday!

Well done Steve, must be a good feeling.

Awesome, truely awesome

Great stuff Steve.

One thing though - have you actually checked the vacuum readings stability on a gauge? With stock ports I think it would be steadier than you think as large overlap is the root cause of a lot of unstable map readings, which of course the stock port timing would have very limited amounts of.

This would allow you to run the speed/density 13b map, with a -15% trim to get started.

Sweet!

Cheers guys. Can't wait for saturday and to get out and drive her

RamoNZ wrote:Great stuff Steve.

One thing though - have you actually checked the vacuum readings stability on a gauge? With stock ports I think it would be steadier than you think as large overlap is the root cause of a lot of unstable map readings, which of course the stock port timing would have very limited amounts of.

This would allow you to run the speed/density 13b map, with a -15% trim to get started.

The vacuum is fairly stable for now, but with the ITBs its only pulling 50kpa of vac at idle and at about 10% throttle at low revs its already reading atmospheric, which leaves a big whole in the map really for 10-100% throttle at low revs. The beauty of using this hybrid alpha-n tuning method is that it basically means I use speed density till I reach only a few kpa of vacuum then it switches over to alpha-n.

As you say this means I can start with a 13b base map -15% and that is exactly how I got it started. It's running ok on light throttle as in that video, but when I throttle down it's struggling because thats when it moves to the un-tuned alpha-n.

Amazing stuff Steve, as my dad says "ther aint arf some clever bas***ds"

Steve-A wrote:Cheers guys. Can't wait for saturday and to get out and drive her

RamoNZ wrote:Great stuff Steve.

One thing though - have you actually checked the vacuum readings stability on a gauge? With stock ports I think it would be steadier than you think as large overlap is the root cause of a lot of unstable map readings, which of course the stock port timing would have very limited amounts of.

This would allow you to run the speed/density 13b map, with a -15% trim to get started.

The vacuum is fairly stable for now, but with the ITBs its only pulling 50kpa of vac at idle and at about 10% throttle at low revs its already reading atmospheric, which leaves a big whole in the map really for 10-100% throttle at low revs. The beauty of using this hybrid alpha-n tuning method is that it basically means I use speed density till I reach only a few kpa of vacuum then it switches over to alpha-n.

As you say this means I can start with a 13b base map -15% and that is exactly how I got it started. It's running ok on light throttle as in that video, but when I throttle down it's struggling because thats when it moves to the un-tuned alpha-n.

Interesting the low vacuum figure realised there, I know of plenty of cars running the 'injection perfection' style throttle bodies and aftermarket ecus which are map based. Of course these are generally turbo so boost figures are easier to capture and ultimately more important but having crap vacuum figures would surely affect these cars in part throttle/off boost situations too one would have thought.

Perhaps there is a more ideal place to take off a vac reference in the manifold? Or maybe it's simply the size of the tbs as you mentioned..

That is interesting. As you mention my throttle bodies are pretty big, I sized them expecting to upgrade to bigger ports sometime in the future, but not much bigger than those injection perfection set-ups.

I'll try some different vac points, I've got a few to choose from. At the moment I'm taking vac from as far downstream of the throttle plate as I can before the manifold splits for primaries and secondaries. I'm quite happy to run with this hybrid set-up either way as on the Megasquirt forums it seems to be rated as the ultimate way to run throttle bodies.

I'm all set to make a push to get her back on the road tomorrow then get some tuning done and I'll have a better idea of how its worked out and hopefully get on the dyno in a couple of weeks and see what numbers it's worked out at.