Help with fuel upgrade

[CheaCheaBoy]

I have a 20g turbo installed.
I need expertise on what to get so it runs right.

I want to have the car in a condition where I can drive it everyday getting good MPG.

All fuel mods are stock.

I do have
-720 injectors
-255hp walbro fuel pump.
-fuel pressure regulator and gauge

Im willing to sell this setup it for whatever setup, you DSMERS recommend me for.

 

[Mr Peepers]

What you have listed should support it nicely, just be sure to rewire the 255 while you're at it. All you really have left is to get something to control those injectors/tune.

Something like SAFC and a logger alone won't cut it at this point. The most user friendly option is usually to get a socketed Eprom ECU if you don't have one already http://www.dsmlink.com/faq-eprom.html and either a stage 3 chip from www.dsmcips.com or DSMlink. A chip would be cheaper, but DSMlink allows you to do a lot more such as change injectors while a chip would have to be sent in to be changed. SAFC and a logger is also recommended with a chip to fine tune it, although I've seen people run alright with only a chip. There are many other things you can do which I won't even begin to cover. Search is your friend

Edit: Maintenance is the key for reliability.

 

[CheaCheaBoy]

I do want to do the dsmlink but
money is a factor.

I also burnt my ecu,
if I get the socketed ecu for later upgrade,
will it for fine with my stock setup?

 

[Mr Peepers]

If you get the chip burned yes it will work fine for a stock setup in the meantime. Get it burned for the 720's and throw them on when you put the ECU back in. You cannot put the stock injectors when the ECU is burned for a different size though.

 

[CheaCheaBoy]

so when i get it burned(where can i do this? and is it on a socketed ecu?),
i throw in my 720 injectors.

my car will run fine without a tuning program?

 

[DirtyBirdRacing]

so when i get it burned(where can i do this? and is it on a socketed ecu?),
i throw in my 720 injectors.

my car will run fine without a tuning program?

No, you will need a tuning tool to get it spot on for your car. As you know every car is a little bit different so the chips will get you real close but not spot on.

Bill

 

[Mr Peepers]

No, you will need a tuning tool to get it spot on for your car. As you know every car is a little bit different so the chips will get you real close but not spot on.

Bill

Assuming the 255 and afpr is installed properly and set to the stock base fuel pressure: If he just wanted to run a basically stock setup I would think that is ok, right? If all cars are a little bit different, then the stock setup would be a little off too. With a chip you are basically making the ECU run the 720's like the stock 450's, so wouldn't there be little to no difference? Correct me if I'm wrong, but I don't see any ill effects, only a little protection from overrunning the stock injectors/fuel system. Just curious.

I recommend saving your money nevertheless, I don't see a need to get a chip burned now.

 

[oldman]

Assuming the 255 and afpr is installed properly and set to the stock base fuel pressure: If he just wanted to run a basically stock setup I would think that is ok, right? If all cars are a little bit different, then the stock setup would be a little off too. With a chip you are basically making the ECU run the 720's like the stock 450's, so wouldn't there be little to no difference? Correct me if I'm wrong, but I don't see any ill effects, only a little protection from overrunning the stock injectors/fuel system. Just curious.

Have you ever run a chip alone? They are never perfect and tuning/logging device is till needed for fine tuning, not to mention a big part of tuning is power gain through the leaning out process of the stock 9.5:1 AFR.

CheaCheaBoy, unless you already have a 95' eprom ECU, your cheapest option is to lower your AFPR so your 720s flows like 660s, then use SAFC/logger combo for tuning. Obviously it would be different if money isn't an issue.

 

[Mr Peepers]

No I have not, I was curious about the dynamics of the chip and if it was possible in his context; running it with a stock setup. If the boost was set to wastegate pressure, I was curious if he(anyone) could run larger injectors and a chip with no problems until they got a hold of an SAFC and logger to tune with when the boost was turned up. I know it probably isn't a good idea, I was just curious if it was possible/why it would be worse than a stock setup.

 

[oldman]

No I have not, I was curious about the dynamics of the chip and if it was possible in his context; running it with a stock setup. If the boost was set to wastegate pressure, I was curious if he(anyone) could run larger injectors and a chip with no problems until they got a hold of an SAFC and logger to tune with when the boost was turned up. I know it probably isn't a good idea, I was just curious if it was possible/why it would be worse than a stock setup.

1. I don't think OP has the eprom ECU yet so I don't know why this would be a viable option since he had said money is an issue.

2. There is absolutely nothing to gain if he is going to be running stock wastegate pressure, he can easily do that with the stock 450s.

3. Your assumption that a chip will automatically put you near stock is somewhat misguided, there simply too many variables in play going from car to car, setup to setup. Denso injector especially are know to flow differently than it rating. Case in point, I was trying to do exactly this years ago with a brand new set of Denso 720s and I was running crazy lean (Lukily I had a logger), 5 chips later (thank you steve) I got fed up, pulled the injectors and send them off to FIC for testing, 640cc @ 43.5psi.

Anyone who is familiar with DSMLink can tell you that the global compensation/dead time of the same set of injectors can vary greatly from car to car.

 

[Mr Peepers]

Thanks for the info Bruce If we only lived in a perfect world...

 

[oldman]

No problem.

 

[dsm-onster]

There are 3 variable preventing a MAF metering fuel injection system from reaching it's target A/F ratio in the flashed fuel maps: global fuel flow, injector deadtime, and maf metering.

Aftermarket injectors have been known to vary widely in fuel flow (global) from brand to brand. But not from injector to injector. So, if the flasher knows the brand and cc rating, then he can nail the global good enough to run like stock.

Deadtime has been know to vary widely in fuel flow (global) from brand to brand. But not from injector to injector. BUT!!! supply voltage determines injector dead time as much as brand. Here is where many guys see such distinct differences even w/ the same brand. Our charging systems DO very significantly. However, for WOT, deadtimes become a null issue. So, target a/f ratio is still likely to be achieved during open loop, if the global is accurate.

Mafs can vary in their transfer function (hertz vs. volume flow, baro voltage differences, IAT voltage differences). Yet, I've been able to swap between several working same generation mafs and seen no noticable difference w/ dsmlink. So how much difference does one oem maf have from the next?

Being off .1 or .2 from target a/f ratios is negledgible from my experience and won't cause you to run different from the ecu's intention (the intention of the factory or the intention you give it).

I've seen no difference in quality/consitancy between stock injectors and aftermarket injectors. I've run FIC, PTE, Denso. I've seen stock 450s to be off by 30cc per injector between sets. If injectors that have been tested 50cc different from their flow rating, then suspect an order mix up w/ the vendor. It happens often. In fact, Denso makes 660cc injectors: base injector data. This would explain why Bruce's 720s flowed like 660s (which flow 640cc according to the DSMLink wiki). I would have gotten an exchange and demanded not to have paid for shipping since the wrong injectors were shipped. That's the difference of over 50 potential hp.

Considering that ecus, oem alternators, oem injectors, and the cars on which they are installed are mass produced; then there are likely no real negatives to installing an aftermarket chip burn designed to alter global and common dead time for a particular brand and flow rating of an injector. There will be some difference, but remember that a maf reads the airflow value w/ in its accuracy no matter what upgrades have been done. That is the beauty of maf setups over speeddensity! If the maf is accurate (all DSM mafs are VERY accurate), then things like ±50 µsec deadtime or ±30cc flow is w/in the control of the ecu trims. MAFs read the actual airflow entering the engine at any given moment regardless of setup.

I have installed a vr4 maf and 1000cc FIC injectors. I used the DSMLink wiki to type in my global and dead time. I set dsmlink to know that I have a GVR4 maf and my fuel trims are w/in actually 6%. In a range the ecu can control. And my WOT w/ NO fuel tuning lines up w/ the OEM air/fuel curve fairly well.

If you want to burn a chip, get an safc to lean out and add timing. This will give you more power. But a reflashed chip will run like stock if you have the right injectors and maf for the flash.

Yea, it is far cheaper just to lower your fuel pressure to have the 720s flow like 650s. Then just run an safc.

Run your fuel pressure at 35.5 psi base to achieve this. . .

Adjustment = [(stock injectors) / (new injectors)] - 1
Adjustment = (450 / 720) – 1
Adjustment = 0.625 – 1
Adjustment = -0.375 or –37.5%

Flow factor adjustment for different fuel pressure:
2G Flow Factor = sqrt[(new fuel pressure) / (stock fuel pressure)]
2G Flow Factor = sqrt(35.5 / 43.5)
2G Flow Factor = sqrt(0.816)
2G Flow Factor = 0.90​

What to tune the safc to once you bring your base fuel pressure down to 35.5 psi:

Adjustment w/ new fuel pressure = [(stock injectors) / (new injectors) / (2G Flow Factor)] - 1
Adjustment w/ new fuel pressure = (450 / 720 / 0.90) - 1
Adjustment w/ new fuel pressure = -0.305 or -30.5% w/ the safc

A tdo5h 20g w/ no clip will not likely out flow a set of 650s. However, any upgrade to the turbine (td06h turbine, clip, or bigger turbine housing) will not be usable w/ that small of injector flow. 720s won't be enough, if you clip your wheel significantly or run the td06h turbine. a 20g can flow as much as a 50-trim (w/ the right turbine) if it has proper exhaust flow.

 

[oldman]

This would explain why Bruce's 720s flowed like 660s (which flow 640cc according to the DSMLink wiki). I would have gotten an exchange and demanded not to have paid for shipping since the wrong injectors were shipped. That's the difference of over 50 potential hp.

Couldn't, bought it from ebay and sat on it for almost a year before installation. However, the part number on the injector corresponds to 720s. Mine was an odd case as most Denso's actually flow more than its rating, 660=700ish and 720=760ish, I suspect my set were 720 rejects from the factory.

Yea, it is far cheaper just to lower your fuel pressure to have the 720s flow like 650s. Then just run an safc.

Run your fuel pressure at 35.5 psi base to achieve this. . .

Adjustment = [(stock injectors) / (new injectors)] - 1
Adjustment = (450 / 720) – 1
Adjustment = 0.625 – 1
Adjustment = -0.375 or –37.5%

Flow factor adjustment for different fuel pressure:
2G Flow Factor = sqrt[(new fuel pressure) / (stock fuel pressure)]
2G Flow Factor = sqrt(35.5 / 43.5)
2G Flow Factor = sqrt(0.816)
2G Flow Factor = 0.90​

What to tune the safc to once you bring your base fuel pressure down to 35.5 psi:

Adjustment w/ new fuel pressure = [(stock injectors) / (new injectors) / (2G Flow Factor)] - 1
Adjustment w/ new fuel pressure = (450 / 720 / 0.90) - 1
Adjustment w/ new fuel pressure = -0.305 or -30.5% w/ the safc

Show off!!!

You never did show him how you got the 35.5psi which is the most important part of his calculations.

2G flow factor = sqrt (new pressure / old pressure)

Since

new flow rate = old flow rate * 2G flow factor
650 = 720 * 2G flow factor
2G flow factor = 650/720 = .903

Therefore

.903 = sqrt (new pressure/43.5)
.816 = new pressure/43.5
new pressure = 35.496 = 35.5psi

To calculate compensation is much easier since the new flow rate value (650cc) was a given value right from the start.

adjustment = (old rate/new rate) -1 = (450/650) -1 = -.3077 = -30.8%

 

[dsm-onster]

Show off!!!

I know what i know and I don't know what I don't.

You never did show him how you got the 35.5psi which is the most important part of his calculations.

2G flow factor = sqrt (new pressure / old pressure)

Since

new flow rate = old flow rate * 2G flow factor
650 = 720 * 2G flow factor
2G flow factor = 650/720 = .903

Therefore

.903 = sqrt (new pressure/43.5)
.816 = new pressure/43.5
new pressure = 35.496 = 35.5psi

To calculate compensation is much easier since the new flow rate value (650cc) was a given value right from the start.

adjustment = (old rate/new rate) -1 = (450/650) -1 = -.3077 = -30.8%

Yea. I thought I'd do the math for him.