Extra injector before TBI - How can I control it?

[Ricardo_Penteado]

Hi guys, this is my first post here. I´ll ask for your apologizes, because you´ll see that my english is a little bit rusty .

I had just bought a MSIIV3.0 kit. For instance, I´m still studying the best configuration to use in my car (VW 1.8 turbocharged - 14 PSI of boost).

Here in Brazil (where I live) is quite common to use the configuration I use nowadays: four injectors to feed just the aspirated phase, and an extra injector controller by a piggyback module to feed the pressurized phase (under boost).

I was thinking about using this same configuration (talking about the injectors), but of course without the piggyback module. The advantage of using this extra injector in the pressure line is that it provides kind of a "intercooler effect" in the moisture, especially due to the fuel we use here (alcohol).

I was thinking about using one injector output to drive the four primary injectors, and the other output to drive the extra injector. But I believe that I´ll have some problems with this configuration: I noticed that there´s no way to configure two different kinds of injectors in Megatune, and also there´s no way (at least I haven´t discovered until now... ) to configure the extra injector to work only under boost.

Do anybody here had already tryed something like this?

Any kind of help would be welcome!

[schmidt]

Bump !

I'm interested too !
I noticed that in MsNs-Extra it's possible to use 2 constants (one for each VE table)... But in MS-2 I don't know !

Cheers

[efahl]

Sounds like Roger's staging algorithm in the Extra code is exactly what you want. Wire the four tpis to one bank, the tbi to the other and start tuning.

Eric

[schmidt]

Hello Guys,

Ricardo is a friend of mine and we have similar cars (both VW, but I'll "squirt" a turbocharged 1.6L).
The idea of the injector is very used on the streets... About the big injectors, this is not a problem... We have TBI injectors (Rochester) with 925cc/min @ 3 BAR (100% DC) !
Take a look on them :




Of course that you guys will think "Such a terrible solution" but with ethanol works pretty fine ! I can't say that's the best thing since sliced bread, but under 18 PSI in a Garrett (.42 Compressor with 46mm rotor (??)) the IAT stays under 45 Celsius (without intercooler) with an external temp of 25 celsius ... And I must say that the compressor was taking loooots of hot air !

We bought 2 MS-2 Kits, but it's possible to buy 2 HC908 and run MsNs-E, which is quite interesting due all the "add-ons" for the "Turbo guys" !!

Well, changing the MS2 code is an idea too, but in my case, I don't know if I can do that !
I think that soon will be many new features in MS2 like in MsNs-E... But we'll have to wait, or use HC908 until then...

I hope that you guys can understand my english...
Cheers
Daniel Schmidt

[racingmini_mtl]

Daniel,

English is not my first language either (French is) but I don't have any problem understanding you.

Like you say, I think that going with the HC908 and MSnS-extra is probably the best for now for all the turbo features. Since you already have the MS2, you'll be able to upgrade when the features are ported to it.

Since you want to use a 925cc/min injector as the secondary injector, to be able to use the staging in MSnS-E you need to have 4 primary injectors no bigger than 231cc/min. If your primary injectors are larger than that, you will either need to change the code, use dual table mode, or use 2 (or more) large injectors to be able make this work.

Hope that helps.

Regards,
Jean

[schmidt]

Daniel,

English is not my first language either (French is) but I don't have any problem understanding you.

Like you say, I think that going with the HC908 and MSnS-extra is probably the best for now for all the turbo features. Since you already have the MS2, you'll be able to upgrade when the features are ported to it.

Since you want to use a 925cc/min injector as the secondary injector, to be able to use the staging in MSnS-E you need to have 4 primary injectors no bigger than 231cc/min. If your primary injectors are larger than that, you will either need to change the code, use dual table mode, or use 2 (or more) large injectors to be able make this work.

Hope that helps.

Regards,
Jean

Jean,

It's perfectly possible to use 2 or more of these big injectors. Those 2 in the pics are in my desk ready to run!
The problem running on ethanol (our ethanol isn't pure, contains 8% of water) is that the stoich AFR is 8.22... So we need REAL big injectors to supply the engine demand... Then people usually use the original injectors 50% bigger and 1 or 2 in the "pipe"...
But there's a BIG con ... If the big injector fail you'll run lean and can melt down your piston head !
Well, In my case I still have some time to think and plan the things (like 7 months), but Ricardo's car is already running and it's more "urgent" !

Cheers !

[Ricardo_Penteado]

Still about the doubt I exposed in the first post, isn´t that possible to be made using two VE tables? The first of them would control the four primary injectors, and the other table only to control the extra injector under boost...

[mops]

alternatively, i believe it will be possible to turn fast idle outpu on ms2 into driver for such injector. it's a pwm output, i'm just not sure whether software allws you to configure it that way (without any modifications to the code).

i vaguely recall somebody was talking about it on those forums at some stage....

[fscott]

I don't know if this will work, so don't blame me if it blows up.

Set up each bank to run two of your main injectors.

Wire the extra injector to one of the two banks through a pressure switch that activates when the boost rises to the right level. As boost comes on, the extra injector starts pulsing.

Tune the VE table normally. When you tune the high MAP parts of the VE table, you'll be adjusting to compensate for the extra injector coming on.

Your table will look kind of wierd, but I think it'll work.

Fred

[mops]

just out of intrest, do you position that extra injectors before or after turbo ?

I'm asking cos there's this theory that before turbo gives you better results in terms of lowet charge temp and better fuel atomization, but can damage the turbo....

[Ricardo_Penteado]

I don't know if this will work, so don't blame me if it blows up.

Set up each bank to run two of your main injectors.

Wire the extra injector to one of the two banks through a pressure switch that activates when the boost rises to the right level. As boost comes on, the extra injector starts pulsing.

Tune the VE table normally. When you tune the high MAP parts of the VE table, you'll be adjusting to compensate for the extra injector coming on.

Your table will look kind of wierd, but I think it'll work.

Fred

Thanks Fred, I also think that this should work, but I´d like to use a "cleaner" solution, without pressure switches. I am still thinking about using two VE tables, setting 0 value to the boosted part of the table, but I´m not sure if this will work...

[Ricardo_Penteado]

just out of intrest, do you position that extra injectors before or after turbo ?

I'm asking cos there's this theory that before turbo gives you better results in terms of lowet charge temp and better fuel atomization, but can damage the turbo....

Well, in my car, the extra injector is positioned after the turbo. Take a look:



But it is also quite common here in Brasil to use the extra injector before the turbo, most cases in drag racing cars. In street cars I believe that I´ve never seen it.

But about the charge temp, I think that after the turbo is the best solution, because here we use alcohol, not gasoline. Just to have an idea, after riding under boost for a certain period, if I pop the hood and place my hand over inlet manifold, it is possible to notice that it is quite cold!

[Ricardo_Penteado]

Sounds like Roger's staging algorithm in the Extra code is exactly what you want. Wire the four tpis to one bank, the tbi to the other and start tuning.

Eric

Eric, can I use this algorithm in MSIIV3.0? Where can I find it?