MPGs run, Aspire SE

[Pu241]

Wonder if there is anyway to use a knock sensor and somehow hook it to a fast response photon emiting element to give you an indication of detonation?
anyone done or know how to do this?

[getnpsi]

Super afc fuel controllers had them but only worked with certain cars. Surprise surptise ive never owned a car that got to exploit that feature. If you can implement just that sensor and it come out the right data with key on voltage to be intetpretted...well now youre spending as much time and money as a standalone that has those features too.

[Pu241]

Thought the Capri had a knock sensor?
Now I don't know how or if it produced a signal that could be used to give us some sort of output.
Also, you make a good point, how much is a standalone knock sensor with some sort of output a human can use directly?


OK, per e-Bay knock sensors can be relatively cheap, but don't know enough about them to know if the output can be used directly or must be interfaced with some sort of transducer to produce a human identifiable signal.

[TominMO]

With 91 octane and 13 degrees BTDC, I am not worried about knock. I do wonder if advancing the timing might in effect give me a too-lean situation, with a non-stock-configuration cam, because some of the fuel gets burned up "too soon". Must call Matt about this.

[Pu241]

I'm sure you'll be fine with that advance and 91 Octane.
I'd just like to be able to see if you can tell the difference between 91 and 89 or 89 and 87.
If you can't, then you win with both MPG and lowest cost fuel.

I know in my OEM festiva's I get better MPG from 89, but in my BP it makes no difference.

[getnpsi]

Thought the Capri had a knock sensor?
Now I don't know how or if it produced a signal that could be used to give us some sort of output.
Also, you make a good point, how much is a standalone knock sensor with some sort of output a human can use directly?


OK, per e-Bay knock sensors can be relatively cheap, but don't know enough about them to know if the output can be used directly or must be interfaced with some sort of transducer to produce a human identifiable signal.

exactly. the modify vam/maf tricks via superAFC only work with certain mazda ecus to start with...i think the capri is one you cannot which sucks because that is the turbo one. Now, knock sensors use algorithm or piezo blah blah something i know nothing about, but enough to know you cant buy a supra turbo knock sensor that has the same npt as a plug in our head, and simply screw it in, wire her up. I WISH LOL..I think FB71 explained why the correct way in detail when it was brought up a few years back.

[TominMO]

I'm sure you'll be fine with that advance and 91 Octane.
I'd just like to be able to see if you can tell the difference between 91 and 89 or 89 and 87.
If you can't, then you win with both MPG and lowest cost fuel.

I know in my OEM festiva's I get better MPG from 89, but in my BP it makes no difference.

I can easily go to 87 by just dialing back the timing. But Matt said I might be able to use 87 even with advanced timing. At this point I am just being cautious, since I have had no opportunity to test the cam with different octanes and timings.

[getnpsi]

I would drive it uphill at less than full throttle and back timing off just enough on 87 so it pings only in the wrong gear. When you stab gas or downshift it richens mixture and knock goes away. That way you are pretty much maxxed out for 89, not really leaving anything on the table. If you are the only driver and know how it behaves you can probably be even more aggressive with this seat of pants pseudo threshold.

[TominMO]

Yeah, I'm thinking eventually 89 will be my octane of choice.

[jason_]

Octane is added to enforce/encourage spark ignition, not ignition from heat/compression combination. It does have it's limit, and more sensitive as CR/advance is increased. A major issue with high CR is it burns too fast and retarding won't help slow the chemical reaction. Also As throttle is opened pcm encourages sooner spark advance, even back when vacuum advance on a HEI was king dog..... Odb2 on a gm vortec real-time shows sometimes scaling 40* advance. Maybe you might need a different algorithm tune to really and fully play with octane/ignition values.

I shaved 048 off my head, then compression is so high, it pings on 93 when she's near calling for electric fan, regardless of my 160* tstat, and the cam timing is so goofy, with factory marks I can't advance then distributor enough to reach factory 10*, so best I can do is 8 and then she sounds like a box of marbles with more then 10 mins of stop and go traffic. Not to mention lugging gas farm equipment were always lower compression. So much easier on bearings, especially on starts from overnight with no oil in system. And back 40 years ago gas was hotter, not yellow, and wouldn't goo up carbs after the bowl evaporating a few times...

Octane is quite picky on heat, compression, and duration. Spark is irrelevant, fuel will ignite always with introduced spark. .

This is where the line is drawn between a gas and diesel, and indirect/direct injection, respectively.

Gas with direct injection is a different ball game, especially with hydraulically adjustable DOHCs... Mmmm...

Food for thought .



Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

[getnpsi]

Agreed. I was just stating how to deal with what youre dealt. Work it harder tune for more than you normally see and that is your safety margin. Pretty broad as we are talking n/a too. Put three huge gorditas in aspire, youll ping again.

[jason_]

Maha, fixed my ignition timing from head shave/dist not able to turn far enough..... DREMEL! I can do 12* comfortably on 93 if I don't work it and keep moving. Climbing 1mile grades making heat she'll occasionally chatter with throttle tease.

Next is someday I'll order an adjustable cam gear. Anyone want to go half's on a dohc order? I only need one.

Apologies for off topic.

Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

[Festevil3]

Maha, fixed my ignition timing from head shave/dist not able to turn far enough..... DREMEL! I can do 12* comfortably on 93 if I don't work it and keep moving. Climbing 1mile grades making heat she'll occasionally chatter with throttle tease.

Next is someday I'll order an adjustable cam gear. Anyone want to go half's on a dohc order? I only need one.

Apologies for off topic.

Sent from my rooted HTC Supersonic using Tapatalk 2 Pro

I would be interested in going halfs on a dohc order just let me know when your ready 704-794-2041 (pm box is full at the moment)

[TominMO]

OK, this is gonna take some explaining....

Went out early this morning and did a 241-mile MPG run @ 60 MPH, on the usual road course (I-70 in IL, east from St Louis). It took 4.6 gallons to refill, for a fuel economy of 52.4 MPG. With the stock cam under basically identical conditions, I got 51 MPG.

I had timed the ignition at 13 BTDC, and used 91 octane. I did that because Matt said there was a possibility that I would lose some power with the new cam, and I didn't want that to happen. But the system might be happier with 10 degrees, in terms of fuel mileage. So today I am going to return the ignition to 10 BTDC; I just filled it w/89 octane. My next run will be with 10 degrees, but Matt says I can safely go to 87 octane, so the next fillup will be with 87.

I called Matt and reported the results; we had a long discussion about the cam design, EFI, and how basically the system needs to get used to the new cam parameters, and that quite likely fuel mileage will go up. Also, since he will be sending me his adjustable FPR and the header, I can expect mileage to improve when I install them, and back fuel pressure off by about 10%. The header will improve flow. I am not sure what effect this will have on mileage, tho.

[mikeyjd]

OK, this is gonna take some explaining....

Went out early this morning and did a 241-mile MPG run @ 60 MPH, on the usual road course (I-70 in IL, east from St Louis). It took 4.6 gallons to refill, for a fuel economy of 52.4 MPG. With the stock cam under basically identical conditions, I got 51 MPG.

I had timed the ignition at 13 BTDC, and used 91 octane. I did that because Matt said there was a possibility that I would lose some power with the new cam, and I didn't want that to happen. But the system might be happier with 10 degrees, in terms of fuel mileage. So today I am going to return the ignition to 10 BTDC; I just filled it w/89 octane. My next run will be with 10 degrees, but Matt says I can safely go to 87 octane, so the next fillup will be with 87.

I called Matt and reported the results; we had a long discussion about the cam design, EFI, and how basically the system needs to get used to the new cam parameters, and that quite likely fuel mileage will go up. Also, since he will be sending me his adjustable FPR and the header, I can expect mileage to improve when I install them, and back fuel pressure off by about 10%. The header will improve flow. I am not sure what effect this will have on mileage, tho.

So initial results are inconclusive I guess. Thank you very much for your willingness to share your results with us. I look forward to following you future tests to see if there are any more notable increases. While your results (1.4mpg) is a 4% increase in economy. I was hoping for closer to the advertised 7mpg (20%). I think it's probably to early to tell what the results are, but it seems that initial reports at what % increase to expect might have been on the hopeful side.