Why bigger injectors?

[Decible]

xdi sells an upgraded gdi pump, which I happen to have. On stock injectors you can get about 10% more gdi flow and run a higher pressure. But you still can’t get by on stock port injectors.

Mike was is the cc’s of the stock DI injector. I read somewhere a year or so ago xdi was going to offer an upgraded di injector with the pump. Not sure the ever did.

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[engineermike]

most tuners hate the gdi, and we have found the cars typcially make more power as you lower the di mix, we just went through this on our 22f150 truck

as we decreased the di mix , power would climb, you wouldn't think that would be the case but the dyno doesn't lie

I'd be really interested in comparing your dyno pulls, log data, and calibration to reconcile these results with my own. I have found that power is sensitive to SOI and GDI pressure, and VERY sensitive to EOI which is also related to pressure. If any of these are less-than-optimal, then reducing blend will reduce the negative effects for sure. I've lost over 100 hp on the dyno just letting the EOI fall too late, but that doesn't directly mean the blend is too high.

A greater GDI blend (optimized within the limits stated above) will allow more spark timing before knock, which as we know is critical to making power in these 12/1 engines.

 

[engineermike]

Mike was is the cc’s of the stock DI injector. I read somewhere a year or so ago xdi was going to offer an upgraded di injector with the pump. Not sure the ever did.

If my conversion is right then they are about 17 Cc/s or 1000 Cc/min at 100 bar.

Supposedly xdi was going to sell them and I’ve heard of dealers getting their hands on some but they still don’t show up on the xdi website.

DW makes some 1700’s but I’ve heard rumors of issues. I even went down the path of converting to ecoboost injectors but every one I found either didn’t fit or I didn’t have access to the correct cal data.

 

[Decible]

If my conversion is right then they are about 17 Cc/s or 1000 Cc/min at 100 bar.

Supposedly xdi was going to sell them and I’ve heard of dealers getting their hands on some but they still don’t show up on the xdi website.

DW makes some 1700’s but I’ve heard rumors of issues. I even went down the path of converting to ecoboost injectors but every one I found either didn’t fit or I didn’t have access to the correct cal data.

I just saw the DW’s last I looked xdi did have a set for the EcoBoost at one time on their website and I didn’t even think about the cal data for the injector

 

[engineermike]

@Decible this is why I wanted to go with ford oem injectors. I have access to the injector data in the other stock tunes. However, it has various levels of completeness just depending on how much effort hpt put into os table definitions. As luck would have it, an injector of the right size, right connector, and with all data defined doesn’t exist.

 

[Decible]

@Decible this is why I wanted to go with ford oem injectors. I have access to the injector data in the other stock tunes. However, it has various levels of completeness just depending on how much effort hpt put into os table definitions. As luck would have it, an injector of the right size, right connector, and with all data defined doesn’t exist.

isn’t that usually how it works out in the car world

 

[bankyf]

If my conversion is right then they are about 17 Cc/s or 1000 Cc/min at 100 bar.

Supposedly xdi was going to sell them and I’ve heard of dealers getting their hands on some but they still don’t show up on the xdi website.

DW makes some 1700’s but I’ve heard rumors of issues. I even went down the path of converting to ecoboost injectors but every one I found either didn’t fit or I didn’t have access to the correct cal data.

Hellion allegedly had some larger injectors on the car they used to make 1000hp on pump gas. I wonder what they use. They were supposed to offer a kit with pump, cam, and injectors, but that never seemed to happen.

 

[engineermike]

Hellion allegedly had some larger injectors on the car they used to make 1000hp on pump gas. I wonder what they use. They were supposed to offer a kit with pump, cam, and injectors, but that never seemed to happen.

They probably were planning to offer the xdi branded injectors. You can get the exhaust cam and pump off the xdi site as of now, but no injector is listed. It’s weird because you can’t take advantage of what the cam offers without injectors.

 

[cognum]

If you find one I’d like to know who it is. I had to learn it and do it myself. Even xdi was very little help. They knew how to make the pump work properly but no idea how to tune to maximize its performance or optimize the gdi parameters.

Thats really amazing that you figured it out yourself. I'm in the UK and there are some that say they're experts so I'll look around if I go down this route. I would have thought bmw, vw, Toyota etc are all big tuner cars that have been using gdi for 2 decades so they must know a thing or two about it, which should be almost all tuners over here.

 

[engineermike]

Not all the knowledge is able to be transferred from one platform to another. I tried learning from gm and everything in the calibration is defined totally differently. It’s very hard to cross it over. Also the engine characteristics get a vote. I’ve read the Subaru tuners can inject fuel up until like 45 deg btdc-compression or later. I found I lose power if I inject past about 110 deg btdc. I lost over 100 hp injecting to 60 deg btdc!

 

[cognum]

Not all the knowledge is able to be transferred from one platform to another. I tried learning from gm and everything in the calibration is defined totally differently. It’s very hard to cross it over. Also the engine characteristics get a vote. I’ve read the Subaru tuners can inject fuel up until like 45 deg btdc-compression or later. I found I lose power if I inject past about 110 deg btdc. I lost over 100 hp injecting to 60 deg btdc!

That's a big difference, I guess they are completely different engines though.
Either way I'll let you know if I come across anyone that thinks they know gdi.

 

[engineermike]

Resurrecting an old thread to share something Ford added to the 2024 engine calibration. You may know that borderline knock spark timing has all sorts of corrections and modifiers such as charge temp, engine coolant temp, lambda, etc. I already knew that GDI suppresses knock but there is no table that relates GDI blend to knock in the 2018-2022. However, Ford added this relationship to the 2024 and here it is:

I can't say that I fully understand the row axis, but at any rate you can gather that GDI can add anywhere from 1.5 to 3 deg of borderline knock resistance at high rpm. Based on some other rules of thumb I've come to know, I believe the 3 number is more accurate.

 

[Angrey]

Resurrecting an old thread to share something Ford added to the 2024 engine calibration. You may know that borderline knock spark timing has all sorts of corrections and modifiers such as charge temp, engine coolant temp, lambda, etc. I already knew that GDI suppresses knock but there is no table that relates GDI blend to knock in the 2018-2022. However, Ford added this relationship to the 2024 and here it is:

I can't say that I fully understand the row axis, but at any rate you can gather that GDI can add anywhere from 1.5 to 3 deg of borderline knock resistance at high rpm. Based on some other rules of thumb I've come to know, I believe the 3 number is more accurate.

In fairness, it looks as though on a straight PI setup, you're getting 6 degrees less than if you ran 100% direct.

That's pretty compelling to increase or run as much DI as possible. It's curious that Terry's posts indicate they observed a drop in power heading that way. Something offsetting and even more impactful must have been at work.

Can you explain "EOI"?

 

[engineermike]

It's curious that Terry's posts indicate they observed a drop in power heading that way. Something offsetting and even more impactful must have been at work.

Can you explain "EOI"?

EOI, I'm betting, is what led to an incorrect conclusion regarding GDI blend vs power.

EOI is the GDI end-of-injection, and there is an EOI clip in the tune. GDI injection starts on the intake stroke at a simple programmed crank angle "SOI 1-shot intake" time. The end time "EOI" is controlled by high-select and the greater of a number of values: warm blend x fuel demand, max injection angle x safety factor, or EOI clip. I've dyno tested different EOI clips and found a huge power loss if you let EOI go too far into the compression stroke, up to 100 hp lost.

So it turns out that it's published that EOI clip should be lowered in order to get that "limit" out of the way. Stock I believe is around 100 deg BTDC (though the final clip is a more complicated calculation output based on, and typically higher/earlier than, this number). I've seen it published and popular aftermarket tuners set this to 49 deg. On the dyno, I've lost power at anything under about 70 deg. If the actual EOI is extending far enough back to hit this clip at 49 deg, then you are definitely losing power. Lowering the blend can pull EOI earlier off the clip, and result in more power. However, the increase in power wasn't due to less blend, it was due to earlier EOI.

So my years of experience on this, take it or leave it, is that the warm 1-shot SOI can be tweaked to optimize. Too early like in the 330+ range sprays fuel onto the piston and loses the GDI advantage. The stock numbers or close to them can generally be used here. EOI clip shouldn't be less than 75 or 70 at the lowest. Warm blend should be set to 90%. If the other limits of the system won't allow it to reach 90% then it will run as high as possible. The logic automatically sends all fuel flow the GDI system can't support through the port injectors. One other thing that can be done to improve blend, power, and knock suppression is to increase the GDI pressure. In the past I'd felt pretty comfortable increasing this from 2900 to 3100 or 3200. However, the 2024 increased the pump-protection pressure limit from 3000 to 3600 and the GDI pump is the same part number as before, so maybe there's a little more to be had there. Increasing the pressure will achieve more flow/blend within the available GDI window.

 

[K4fxd]

Some good info there, thanks Mike.

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