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  #46  
Old 07-20-2005, 02:29 AM
Duckie Duckie is offline
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Oops, i meant 17's on my car...not 16's lol
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  #47  
Old 07-20-2005, 02:38 AM
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Quote:
Originally Posted by mbtoloczko
100% may be the true max, but no one who tunes motors will recommend running anything over 85% duty cycle. I've seen flow rate vs fuel pressure curves from an SVX fuel injector, and I'd bet anything that its impossible to get 350 BHP from a boosted (SC or turbo) SVX motor running stock fuel injectors without running at least 60 psi line pressure. I'd say a more realistic number is a line pressure of 70 psi, and that may not be enough.

I'm trying to make a clear point here and I'm not sure if you aren't getting it or you are trying to defend your #'s besides it confusing the point i'm trying to make. Fuel injector size calculations using bsfc and desired hp are a good way to decide what fuel injectors to purchase if you are purchasing fuel injectors; however, it is not valid to say that because a calculation using bsfc and desired hp says you should have larger fuel injectors that you can not use the fuel injectors you have. When flow rate is accepted as is the factor limiting how much power you can generate is how much time the injector has to inject fuel. If you give it long enough 1 small injector can fill a barrel with fuel. The time the injector has to inject fuel gets shorter as rpms increase and thus it is at high rpms that the injector will max out first. Maybe this will make it clearer. While the thing we are changing with forced induction is how much air we are putting into the cyllinder with each stroke it is not that the fuel injector can't put enough fuel into the cyllinder for that air it's a question of at what rpm will it no longer be able to put enough fuel into the cyllinder. I'm not going to redo the calculations so this will be ballpark # from the top of my head: at 2800 rpms you have 34 milliseconds to inject fuel into each cyllinder(a lifetime), at 4200 rpms you have 25 and half milliseconds (an awfully long time), at 5600 you have 17 milliseconds (a pretty long time). As your rpms increase the time you have to inject fuel into each cyllinder decreases and somewhere allong the yellow brick road your fuel injectors will not be able to keep up. I can't tell you exactly what rpm this will happen at. It will vary by system and you will not know till you get there. I can tell you though that your car will be plenty drivable while you decide if you want to adjust your boost down to a level the injectors can keep up with at the rpm you want to run or get an additional injector controller, or run higher fuel pressure, etc etc. I can tell you that with the additional power you'll have at low rpms you wouldn't find yourself even wanting to go into high rpms in around the town driving while you figure out what to do for additional fuel. And I can tell you that you will be better able to nail down any other bugs in your newly crafted custom system before doing anything about additional fuel. And I can tell you that you will understand things and be able to make a better choice about if and what to purchase for more fuel after you have driven your working system and nailed down any bugs. Reading is great but you don't really know what you are talking about untill you are there.

Your fuel injector size calculator may tell your injectors aren't big enough but what they don't tell you is:

1) they are big enough for the majority of operating time even if they aren't big enough for high rpms
2)you may be happy to turn down the boost to where they are big enough instead of increase fuel
3)you may want to do combinations of things like increase fuel pressure and bring down boost
4)an additional injector controller can be implemented easiest to get you into the higher rpm ranges after you have your system humming with all the bugs worked out

The short of it is that untill you have your system working you are really just speculating and the stage 2v3 software is plenty to get your system working and will handle all or close to all operating conditions. Then engine management is no longer a legitmate hold back. If you need additional fuel it will only be under throttle at high rpms and that can be done after your system is built and without screwing with the engine management.
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  #48  
Old 07-20-2005, 03:37 AM
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Quote:
Originally Posted by poweredx2
Well I have access to a few 90-96 maximas and two 94 na 300zxs.Do I have to switch connectors.
Does Maxima's MAFs are the same of the 300 ZX's ? i mean do they have the Z32 type? if it is so i can easily get it from here, if not i have to search for the 300ZX's which is very hard to find because this car was never imported to Lebanon by the Nissan dealership... any help?
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  #49  
Old 07-20-2005, 04:57 AM
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Quote:
Originally Posted by longassname
I'm trying to make a clear point here and I'm not sure if you aren't getting it or you are trying to defend your #'s besides it confusing the point i'm trying to make. Fuel injector size calculations using bsfc and desired hp are a good way to decide what fuel injectors to purchase if you are purchasing fuel injectors; however, it is not valid to say that because a calculation using bsfc and desired hp says you should have larger fuel injectors that you can not use the fuel injectors you have. When flow rate is accepted as is the factor limiting how much power you can generate is how much time the injector has to inject fuel. If you give it long enough 1 small injector can fill a barrel with fuel. The time the injector has to inject fuel gets shorter as rpms increase and thus it is at high rpms that the injector will max out first. Maybe this will make it clearer. While the thing we are changing with forced induction is how much air we are putting into the cyllinder with each stroke it is not that the fuel injector can't put enough fuel into the cyllinder for that air it's a question of at what rpm will it no longer be able to put enough fuel into the cyllinder. I'm not going to redo the calculations so this will be ballpark # from the top of my head: at 2800 rpms you have 34 milliseconds to inject fuel into each cyllinder(a lifetime), at 4200 rpms you have 25 and half milliseconds (an awfully long time), at 5600 you have 17 milliseconds (a pretty long time). As your rpms increase the time you have to inject fuel into each cyllinder decreases and somewhere allong the yellow brick road your fuel injectors will not be able to keep up. I can't tell you exactly what rpm this will happen at. It will vary by system and you will not know till you get there. I can tell you though that your car will be plenty drivable while you decide if you want to adjust your boost down to a level the injectors can keep up with at the rpm you want to run or get an additional injector controller, or run higher fuel pressure, etc etc. I can tell you that with the additional power you'll have at low rpms you wouldn't find yourself even wanting to go into high rpms in around the town driving while you figure out what to do for additional fuel. And I can tell you that you will be better able to nail down any other bugs in your newly crafted custom system before doing anything about additional fuel. And I can tell you that you will understand things and be able to make a better choice about if and what to purchase for more fuel after you have driven your working system and nailed down any bugs. Reading is great but you don't really know what you are talking about untill you are there.

Your fuel injector size calculator may tell your injectors aren't big enough but what they don't tell you is:

1) they are big enough for the majority of operating time even if they aren't big enough for high rpms
2)you may be happy to turn down the boost to where they are big enough instead of increase fuel
3)you may want to do combinations of things like increase fuel pressure and bring down boost
4)an additional injector controller can be implemented easiest to get you into the higher rpm ranges after you have your system humming with all the bugs worked out

The short of it is that untill you have your system working you are really just speculating and the stage 2v3 software is plenty to get your system working and will handle all or close to all operating conditions. Then engine management is no longer a legitmate hold back. If you need additional fuel it will only be under throttle at high rpms and that can be done after your system is built and without screwing with the engine management.

Thanks very much for all this meticulous explanation Michael. It makes it easier to see that a rolling test bed can be done, without harm.

One point I see that would be relevant for forced induction. Bolting on a turbo would seem to be easier than a supercharger. However, the turbo is normally giving its best power at high rpm, where the belt driven Roots or twin screw is delivering full pressure off tickover. This implies to me that anyone considering a turbo will be more likely to run into the maxed out injector problem at high revs, because that is where they are getting their best fun to money ratio.

The supercharger will give you all the power at low rpms where even the stock injectors will work. That is why I am going to fit a blower. I will be going with the bigger intank pump, higher pressure and maybe 550cc injectors anyway, but nice to know the stock system would work OK.

Thanks again,

Joe

PS I will be wanting the Stage 2 v 3 from you
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  #50  
Old 07-20-2005, 11:13 AM
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Quote:
Originally Posted by SilverSpear
Does Maxima's MAFs are the same of the 300 ZX's ? i mean do they have the Z32 type? if it is so i can easily get it from here, if not i have to search for the 300ZX's which is very hard to find because this car was never imported to Lebanon by the Nissan dealership... any help?
No I don't think it is the same meter; however, an infity j30 is the same.
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  #51  
Old 07-20-2005, 11:15 AM
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Just a quick question for ya Mike. Sometimes when I hit WOT in first and second my car seems to buck. i have a feeling it is because I am pulling too much air and maxing out the MAF. Is this possible for a car with few mods like mine?

Tom
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  #52  
Old 07-20-2005, 11:18 AM
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Chiketkd Chiketkd is offline
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Michael,

A lot of performance minded members have installed a 43.5psi impreza fpr in their SVXs. How hard and more expensive would it be to offer a Stage 2v3 for SVX's with this fpr?

As you can tell, I have little interest in your Stage 1 OBDII chip, and a lot more in the OBDII version of the Stage 2v3 chip whenever it's released. I just don't want to go back to the stock fpr as I'll be doing some fresh mods on my engine which haven't been undertaken before.

-Chike
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  #53  
Old 07-20-2005, 02:16 PM
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Quote:
Originally Posted by Chiketkd
Michael,

A lot of performance minded members have installed a 43.5psi impreza fpr in their SVXs. How hard and more expensive would it be to offer a Stage 2v3 for SVX's with this fpr?

As you can tell, I have little interest in your Stage 1 OBDII chip, and a lot more in the OBDII version of the Stage 2v3 chip whenever it's released. I just don't want to go back to the stock fpr as I'll be doing some fresh mods on my engine which haven't been undertaken before.

-Chike
As for the obdI line up I offer those products that best meet the needs of the most people. I think the stage 2v3 is a good product that will open up a lot of avenues for performance modification of the svx. You probably do get a performance benefit on your car from an imprezza fpr because you don't have our software and your car would otherwise be running too lean. I believe in most cases it will not improve performance to use an imprezza fpr with our software but that is up to each individual to test and figure out for his or her particular set up. If I tuned the software specifically for an imprezza fpr on a naturally aspirated svx it would be to the detriment of the tuning for forced induction or all those who have naturally aspriated svx's with svx fuel pressure regulators. I listen to all ideas from customers and potential customers to determine the needs, both actual and percieved, of the market and then make the best fit product line to meet those needs. I do appreciate your input but I do not feel that at this time there is sufficient merrit to creating a new product tuned for using an imprezza fuel pressure regulator.

Now let me give you my usual non-answer regarding the obdII stuff: I still can not share any information about when or what we will be releasing for the obdII svx but rest assured that I have listened to everyone during the product development process.
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  #54  
Old 07-20-2005, 02:36 PM
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Quote:
Originally Posted by tomssvx
Just a quick question for ya Mike. Sometimes when I hit WOT in first and second my car seems to buck. i have a feeling it is because I am pulling too much air and maxing out the MAF. Is this possible for a car with few mods like mine?

Tom

You are running a manual transmission so if you are refering to high rpms then yes it is completely possible. If you are referring to low rpms then no. I have not done any personal experimentation/logging/measuring the mass air flow readings on a stock svx. I only know about the software and hardware but I don't know about the airflow on the stock svx from personal experience. This was never needed information for me and this project developed after I no longer had a stock svx on hand to make measurements on in order to give you information to work with. I know the mass air meter maxes out somewhere right around the max output of a stock svx engine but not exactly where. The plots Mychailo posted indicate that the meter is also wildly inaccurate at high airlfows if his log is accurate and his specific case is the case in general then whether you are actually at the max reading on the meter or in the wildly inaccurate reading area of the meter then the maf reading should be suspect for any problems you are running into.
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  #55  
Old 07-20-2005, 06:56 PM
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Originally Posted by longassname
Now let me give you my usual non-answer regarding the obdII stuff: I still can not share any information about when or what we will be releasing for the obdII svx but rest assured that I have listened to everyone during the product development process.
Understood. I'll be waiting - with cash in hand.

-Chike
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  #56  
Old 07-21-2005, 12:08 AM
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Quote:
Originally Posted by longassname
No I don't think it is the same meter; however, an infity j30 is the same.
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  #57  
Old 07-21-2005, 03:21 PM
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Quote:
Originally Posted by Chiketkd
Understood. I'll be waiting - with cash in hand.

-Chike

DITO

I am just excited it is even a possibility. . .
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  #58  
Old 07-21-2005, 04:26 PM
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Quote:
Originally Posted by ssnsltd
DITO

I am just excited it is even a possibility. . .
The only other possibility is to go to a tuner shop w/ dyno and have them dyno tune your car. This will get around the maxed out maf as they can dial in extra/less fuel & timing at any rpm - but it will be much pricier!

-Chike
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Last edited by Chiketkd; 07-21-2005 at 09:20 PM.
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  #59  
Old 07-22-2005, 10:26 AM
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Quote:
Originally Posted by Chiketkd
The only other possibility is to go to a tuner shop w/ dyno and have them dyno tune your car. This will get around the maxed out maf as they can dial in extra/less fuel & timing at any rpm - but it will be much pricier!

-Chike
You mean using an air flow converter? that merey tricks the esignal. also im not aware of a program that can adjust timing on the stock computer.
phil
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  #60  
Old 07-22-2005, 10:47 AM
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Quote:
Originally Posted by Phast SVX
You mean using an air flow converter? that merey tricks the esignal. also im not aware of a program that can adjust timing on the stock computer.
phil
Maybe timing cannot be adjusted, but the stock ECU is always trying to maximize timing as long as no knock is detected. I do know this particular shop I have in mind has a machine that's able to flash the ECUs of OBDII cars. Either way, most people won't touch an SVX with a ten foot pole.

LAN is doing our community a great service, and I hope he services his OBDII customers as well as he's servicing the OBDI...

-Chike
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