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Have you figured out a price schedule yet? Any idea how this would respond to a more radical cam? I saw earlier responses to this question but was curious about your opinion.

Thanks
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Old 01-23-2004, 07:29 PM
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Quote:
Originally posted by Elombard
Have you figured out a price schedule yet? Any idea how this would respond to a more radical cam? I saw earlier responses to this question but was curious about your opinion.

Thanks
I'm getting closer to a price as I assemble the various parts. Cost is higher than initially anticipated and being in Canada I get dinged on purchases made in the US (duties, broakrage fees, etc...). Its looking to be around $1500. Until I have all the pieces I won't know for sure.

As for radical cams have a look at the meagsquirt yahoo group. Every question imaginable has been posted and answered. Megasquirt has the ablilty to run in 'alpha-N' mode for those running radical cams. In this mode the manifold vacuum is ignored and the throttle position sensor is used to determine engine load. I don't know if this will work for you, though. I think there are firmware versions that will run alpha-N mode for low rpms and then switch to 'speed density system' (manifold pressure) at higher rpms, but your getting into experimental firmware here.

Megasquirt Yahoo group is here:
http://autos.groups.yahoo.com/group/megasquirt/
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'78 911SC with BITZRACING EFI conversion kit
Old 01-23-2004, 07:44 PM
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Don't worry about wild cams, MAP-driven systems aren't so picky about that as those using CIS.

Alpha-N or mixed mode will definately work with wildest cams available.

Pure Alpha-N driven system will have responce of well-tuned carbed engine, but will have typical carb problems as well (it won't be able to compensate for altitude).
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Old 01-24-2004, 02:15 AM
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I have been aksing around about the Megasquirt and have been told that among other things it does not provide enough map resolution for a Porsche especially a turbo. Apparently the early Bosch EFI on the Carrera used to have a 12by12 map which was barely adequate. I can relate to the cost attractiveness of the Megasquirt but does any one know if there will be newer versions which provide higher resolution fuel maps and perhaps ignition control, boost control and a seperate. idle/warmup map. In additoin it would be nice to store more than one map "economy and power", and easily be able to switch between them.
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Old 01-24-2004, 07:31 AM
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Quote:
Originally posted by magic930
I have been aksing around about the Megasquirt and have been told that among other things it does not provide enough map resolution for a Porsche especially a turbo. Apparently the early Bosch EFI on the Carrera used to have a 12by12 map which was barely adequate.
Interesting information.

I know there are at least 3 different ways to control spark with the MegaSquirt, but I have not tried them. Check here, about half way down the thread for a link ("DIY Injection Page") to a lot of information about this:

EFI: Megasquirt question (future product)
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Old 01-24-2004, 08:38 AM
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Megasquirt uses a 8x8 VE table, which I have been running in my 911 and works fine. Note that Megasquirt interpolates between VE table entries using MAP & RPM , so in effect the table has infinite resolution. (If you want to get technical, the MAP resolution is 256 points and the RPM has resolution down to 100rpms). So Megasquirt will automatically generate a VE entry on the fly when the engine is running at a point not covered in the 8x8 table. It doesn't just pick the closest VE entry.

As for boosted engines the MAP sensor has a range of full vacuum to +22psi boost which should satisfy all the Hp junkies out there.

Ignition does exist for megasquirt. It is a spin off the standard software. It uses the idle control line (which will not be used in the Porsche 911 application) to retard timing based on a table of manifold pressure and rpm. I have not used this so I can't say how well it works. It's called Megasquirt'n'spark.

For the real turbo junkies there exists the "dual table" code which allows you to setup of a second 8x8VE table to drive water injection into the manifold to prevent detonation at high boost.
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Old 01-24-2004, 09:33 AM
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TPS update

I've spent the last few days trying to come up with a simple way to mount the throttle position sensor (TPS) to the stock CIS throttle body. The way I did it on my car (look on my web page below) works great, but is not practicle for production. I tried to think of easier ways to mount the TPS, but came up with nothing simpler.

I then though, well if I can't mount it then I should just get rid of it This was a true moment of eureka! So I did exactly that, removed the TPS from the equation.

Here is how. Megasquirt uses the TPS for acceleration enrichement. It looks for a high rate of change in the TPS (ie: pressing the gas pedal quickly) and when it sees it, it dumps extra fuel.

I thought the MAP actually changes when the TPS changes, so why not use the MAP for acceleration enrichement instead? I needed to first see how well the MAP tracks changes in TPS. Megasquirt (MS) has wonderfull logging abilities, so I started up the engine and logged the MAP and TPS sensors as I reved the engine. Here is a plot showing the two.



Looking at the graph it is clear the MAP tracks the changes in TPS perfectly. (remember change is what is important and not the absolute value, first derivative for the engineering types).

This made my day, because one could not come up with a simpler solution to the TPS problem than this. I was getting kinda depressed, and these results have given me a boost again.

So, the conclusion is no TPS is needed! This reduces the complexity of the kit and drops the price too.
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Old 01-27-2004, 06:03 PM
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Soooooo,

Without the TPS, what are we talking now for a full kit? I have a 914/6 (the one recently upgraded to a 2.7) that is begging for an upgrade.

James
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Old 01-27-2004, 06:47 PM
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Quote:
Originally posted by red-beard
Soooooo,

Without the TPS, what are we talking now for a full kit? I have a 914/6 (the one recently upgraded to a 2.7) that is begging for an upgrade.

James
I guessed about $1500 earlier, maybe $100 less now without the TPS. Maybe more or less depending on the rest of the parts.

Things that remain to be worked out are:
Injectors
Wiring harness
Connectors
O2 sensor
CHT sensor
MAT sensor
Fuel pressure regulator
fuel hoses
fuel fittings
Fuses

I think a partial kit of Fuel rails, brackets for the rails, injector bungs and the Megasquirt unit should be enough for someone with DIY capabilities to do the modification. I just need to test out the new software (MAP instead of TPS) and this partial kit should be available real soon.
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Old 01-27-2004, 07:09 PM
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How's the idle using the MAP?
Old 01-27-2004, 07:10 PM
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Quote:
Originally posted by Souk
How's the idle using the MAP?
Idle is unaffected by this change. TPS is only used during acceleration. Megasquirt provides a means of filtering out any small pulses in MAP that could trigger a false 'acceleration enrichement' event.

I've tested this new software with my car runing in the garage (winter here in Ottawa). I could not see any difference in how the engine responeded with TPS versus MAP as the trigger for acceleration enrichement.

I am going to try again tomorrow with the engine being dead cold from the start.
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Old 01-27-2004, 07:18 PM
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Fantastic!! This also means that those of us who want to use some of your parts with MFI TB's may have a prayer. Without the TPS to deal with one could use nearly anything for throttle bodies. Food for thought...

Alex
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Old 01-27-2004, 07:48 PM
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I was looking at my engine the other day, and just in case you still want to put a TPS on the system, you could consider putting it on the bell crank on the block. But sounds like you don't need it now.
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Old 01-28-2004, 05:00 AM
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Alex I am not sure but I dont think your statement will work. All the air still has to go through the MAF i.e. one point not multple points as in multiple throttle bodies. Just a guess??
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Old 01-28-2004, 05:04 AM
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Quote:
Originally posted by Elombard
Alex I am not sure but I dont think your statement will work. All the air still has to go through the MAF i.e. one point not multple points as in multiple throttle bodies. Just a guess??
There is no MAF with Megasquirt. You use MAP (basically just a pressure sensor) and/or TPS.

So yes, you could adopt Megasquirt on MFI stacks running Alpha-N instead of MAP. It will give as instant throttle response as any MFI injection with much better tunability and efficiency.

Of course, there will always be people talking about how ultra advanced MFI's high injector pressure will form special flux capacitor vector droplets to provide extra horsepower, better sound and longer Johnsson.
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Old 01-28-2004, 05:30 AM
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Wow plus no pulses interfering from other runners - and - I am in business with wild Cams!! I suppose completely different injector mounting system would need to be worked up?? Since the MFI stacks I imagine hold different injectors than the CIS runners??
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1994 Lotus Esprit S4 - interesting!
84 lime green back date (LWB 911R) SOLD
RSR look hot rod, based on 75' SOLD
73 911t 3.0SC Hot rod Gulf Blue - Sold.
Old 01-28-2004, 05:43 AM
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Quote:
Originally posted by Elombard
Wow plus no pulses interfering from other runners - and - I am in business with wild Cams!! I suppose completely different injector mounting system would need to be worked up?? Since the MFI stacks I imagine hold different injectors than the CIS runners??
Alpha-N systems doesn't care about pulses, interference or cams. Actually, it doesn't care about anything else but throttle opening and RPM. It's basically an electronic MFI system, but instead of space cam you have infinitely variable fuel maps.

Only bigger problem, as far as i see it, is mounting injectors at suitable spot in those thin resin stacks. I would rather clean Webers from all fueling and make them into throttles, then fit injector bosses at apropriate spot.
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Old 01-28-2004, 06:29 AM
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Thats right the injectors go in the heads, I forgot. How about a beat set of zeniths, they are so cheap? Are you saying drill a hole and braze on a boss? What about rigging up to have them suspended above the body - Like the jerry Woods Moddonna things but cheap? How does that work when the butterflies are closed? seems like the fuel would just spray allover the tops of them and drip every where? Obviously my unerstanding on this is limited... I appreciate your patience.
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1994 Lotus Esprit S4 - interesting!
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Old 01-28-2004, 06:38 AM
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Folks,

Alpha-N uses a TPS. The system I describe above removes the TPS from Megasquirt, so you cannot run Alpha-N mode. You can only run MAP (speed density) mode.

Note, however this is just a software change. There is no reason why people can't go to TPS in the future if they desire to do so. You can mount a TPS and easily download the original software that uses the TPS.

I hope this is clear.
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Old 01-28-2004, 06:42 AM
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Old 01-28-2004, 07:00 AM
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