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Improving Fuel Atomization

This is a discussion on Improving Fuel Atomization within the Computer & Tuning forums, part of the LSx Technical Help Section category; Does anyone know if GM has improved their injector design since 98-02? The reason I ask is because I saw ...

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    Senior Member Naaman's Avatar
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    Improving Fuel Atomization

    Does anyone know if GM has improved their injector design since 98-02? The reason I ask is because I saw another car that had newer injectors retrofitted in place of the 20+ year old design. The ECU was then tuned to account for better atomization (the injectors were also higher pressure, so presumably operated at a lower duty cycle...?). Anyway, the engine gained 35 lbs ft and 17 horsepower just from an injector upgrade.

    I'm wondering if anyone knows of a good starting point to look at different injectors as a way to improve the efficiency (burn more of the fuel) and thereby the output.

    Are the Gen 4 injectors compatible (physically) with the Gen 3 engines? Perhaps the new LT1's injectors will fit? But more importantly, are they better than the LS1 injectors? Any third party stuff that might be worth consideration?

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    Over time, injectors will get dirty or wear out just like any other electrical/mechanical part. Without knowing the condition of the stock injectors its hard to make an apples to apples comparison. Also, the tune probably took into account other variables and you cannot attribute the numbers to simply the injector swap. I think Frost can easily find 10-15 horsepower with a mail order tune on a stock engine without any supporting mods.

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    Senior Member Naaman's Avatar
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    Fair enough, but the situation I'm talking about is well documented in another forum with a thread spanning several weeks (maybe months... memory fails at the moment) with a baseline dyno and an after dyno. Others had the same upgrade done and saw gains as well. The issue, according to the tuners was that the older injectors would "squirt" the fuel into the cylinder, whereas the newer ones had several nozzles (like a shower head) and more psi and "sprayed" fuel more like a mist (improving its ability to mix with the air).

    Its worth noting that there were several nay-sayers when the experiment was presented before the results were posted. Once the results were up, everyone was impressed. I can PM you the link, if you care to see it.

    It's an experiment I'd be willing to try, but I don't know enough about how to evaluate an injector and the combustion process and tuning, etc to know the best place to start. Hopefully, I can find a solution that others can benefit from. Theoretically, a better injector will yield not only more power, but better economy and cleaner emissions, as well (assuming more complete combustion)... at least, I think that's right.... :P

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    There's definetely more advanced injector desings since the original LS1 injector design. The main goal would be to size the injectors to your application whether it be misting at existing fuel pressure or a smaller injector that needs higher pressure. Its just like a spray bottle in which you adjust the tip, you can reduce the pressure and get a plain stream, or increase the pressure and get a fine mist ... both using the same nozzle.
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    Moderator Firebirdjones's Avatar
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    Aftermarket injectors have been practicing this for many years. In the 80's all the buick guys were doing this on their GN's.

    I'm told, increasing fuel pressure sort of accomplishes this theory as well to some degree, which is a trick most of us did on our L98 tuned port engines and the ford guys were doing on their little 5.0 fox bodies back then. I did this on my L98 and on my Typhoon. All these cars seemed to run better with a 3-4 psi bump in fuel pressure.
    Now whether that was due to an increase in AFR, or better fuel atomization, remains to be seen.

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    Senior Member Too Fast's Avatar
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    LT1 injectors from the newest GM LT1 are incompatible, since that engine is direct injected, with fuel rail pressures at the injector in the neighborhood of 400-1500 psi.

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    Senior Member Naaman's Avatar
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    Quote Originally Posted by Firebirdjones View Post
    Aftermarket injectors have been practicing this for many years. In the 80's all the buick guys were doing this on their GN's.

    I'm told, increasing fuel pressure sort of accomplishes this theory as well to some degree, which is a trick most of us did on our L98 tuned port engines and the ford guys were doing on their little 5.0 fox bodies back then. I did this on my L98 and on my Typhoon. All these cars seemed to run better with a 3-4 psi bump in fuel pressure.
    Now whether that was due to an increase in AFR, or better fuel atomization, remains to be seen.
    In the case I mentioned earlier, the newer injectors had both more pressure and better atomization. The stock ones were 27 lbs, while the new ones were 42 lbs. I want to say that they were also from a direct injection design, but maybe not? I'd have to research it. The newer injectors came off of a 2012 RDX.

    Quote Originally Posted by Too Fast View Post
    LT1 injectors from the newest GM LT1 are incompatible, since that engine is direct injected, with fuel rail pressures at the injector in the neighborhood of 400-1500 psi.
    Direct injection would be nice, but in that case, we're looking at an engine swap... Is the 2015 Camaro supposed to get an LT series motor?

    *******

    Here is a link to the post with the results of the project. The thread is rather massive. I remembered incorrectly on the original data. The peak numbers were +17 whp and +13 wtq (peak). Although, you can see on the dyno that there are gains in excess of 25-30 ft.lbs at the lower end.

    http://www.nsxprime.com/forum/showth...=1#post1527059

    Anyway, a lot of the data is over my head. Does anyone think our cars can benefit from something like this? Is it really as simple as better injectors plus a tune? Can the stock PCM be used, or whould I need an upgrade? If stock PCM can be used, it seems like a no-brainer.

    I was looking at FAST 36 lbs injectors. Anyone have a brand that they recommend? I'd be interesed particularly in some GM injectors (Gen 4s, maybe?).
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    Quote Originally Posted by Naaman View Post
    Quote Originally Posted by Firebirdjones View Post
    Aftermarket injectors have been practicing this for many years. In the 80's all the buick guys were doing this on their GN's.

    I'm told, increasing fuel pressure sort of accomplishes this theory as well to some degree, which is a trick most of us did on our L98 tuned port engines and the ford guys were doing on their little 5.0 fox bodies back then. I did this on my L98 and on my Typhoon. All these cars seemed to run better with a 3-4 psi bump in fuel pressure.
    Now whether that was due to an increase in AFR, or better fuel atomization, remains to be seen.
    In the case I mentioned earlier, the newer injectors had both more pressure and better atomization. The stock ones were 27 lbs, while the new ones were 42 lbs. I want to say that they were also from a direct injection design, but maybe not? I'd have to research it. The newer injectors came off of a 2012 RDX.

    Quote Originally Posted by Too Fast View Post
    LT1 injectors from the newest GM LT1 are incompatible, since that engine is direct injected, with fuel rail pressures at the injector in the neighborhood of 400-1500 psi.
    Direct injection would be nice, but in that case, we're looking at an engine swap... Is the 2015 Camaro supposed to get an LT series motor?

    *******

    Here is a link to the post with the results of the project. The thread is rather massive. I remembered incorrectly on the original data. The peak numbers were +17 whp and +13 wtq (peak). Although, you can see on the dyno that there are gains in excess of 25-30 ft.lbs at the lower end.

    http://www.nsxprime.com/forum/showth...=1#post1527059

    Anyway, a lot of the data is over my head. Does anyone think our cars can benefit from something like this? Is it really as simple as better injectors plus a tune? Can the stock PCM be used, or whould I need an upgrade? If stock PCM can be used, it seems like a no-brainer.

    I was looking at FAST 36 lbs injectors. Anyone have a brand that they recommend? I'd be interesed particularly in some GM injectors (Gen 4s, maybe?).
    I suggest Deatschwerks injectors since I have them. They are very high quality injectors, one of the best in the industry and they come with a 3 year warranty as well as tuning data. However they are pretty pricey (mine were $679 for 95#) but you get what you pay for. Also they are Gen 4 style injectors and come with all spacers and harness adapters you will need which is nice.



    These are them with the injector spacer and harness adapter attached. You can use the stock PCM it just takes tuning for the different flow and injector type is all.
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    Senior Member Naaman's Avatar
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    Sweet. Now, with 95 lbs, is that "overkill" for a bolt-ons application?

    Also, from what limited education I have on the matter, I think I remember testing my fuel system back in school, and it specs out at 58 lbs or some such. But I think this is fuel line pressure, not pressure of the injector itself... do I have that right? The stock LS1 injectors are 28 lbs, correct? (Mine is a 98).

    I'm going to try and get a hold of NicD and see what he thinks and whether there are gains to be had based "merely" on the engineering of the injectors. What I'm assuming this all hinges on is achieving "more complete combustion." If combustion efficiency can be improved, then everything related to combustion should see an improvement... I think...

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    Your fuel pressure is measured in pounds per square inch (psi) and yes, our cars operate at 58 psi. Fuel injectors are rated at pounds per hour (lbs/hr) which is their maximum flow capacity at a specified fuel pressure.

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    Those increases can be seen from a tune and happy DYNO alone. Go DYNO the same exact car with the same exact tune on a different DYNO and you'll get different results. Do it on the same DYNO on a different day and you'll get different results. $700+ is a lot to spend on an "experiment" where the same results can be had for $150 (just a tune).
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    Senior Member Too Fast's Avatar
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    Quote Originally Posted by Naaman View Post
    In the case I mentioned earlier, the newer injectors had both more pressure and better atomization. The stock ones were 27 lbs, while the new ones were 42 lbs. I want to say that they were also from a direct injection design, but maybe not? I'd have to research it. The newer injectors came off of a 2012 RDX.



    Direct injection would be nice, but in that case, we're looking at an engine swap... Is the 2015 Camaro supposed to get an LT series motor?

    *******

    Here is a link to the post with the results of the project. The thread is rather massive. I remembered incorrectly on the original data. The peak numbers were +17 whp and +13 wtq (peak). Although, you can see on the dyno that there are gains in excess of 25-30 ft.lbs at the lower end.

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    Anyway, a lot of the data is over my head. Does anyone think our cars can benefit from something like this? Is it really as simple as better injectors plus a tune? Can the stock PCM be used, or whould I need an upgrade? If stock PCM can be used, it seems like a no-brainer.

    I was looking at FAST 36 lbs injectors. Anyone have a brand that they recommend? I'd be interesed particularly in some GM injectors (Gen 4s, maybe?).


    You can't swap direct injection injectors from a direct injection engine into a port fuel injected engine. Incompatible. I don't know if the newest Camaro is getting the LT1 engine, but I bet it will soon. Usually the 'vette gets the newest generation engine, and the Camaro follows a year of 2 behind.

    Jeff explained the injector flow rate/rating and fuel pressure well.

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    Moderator Firebirdjones's Avatar
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    Injector flow patterns and fuel atomization is really splitting hairs for a street car, especially a bolt on daily driver. The whole combustion process is pretty interesting stuff, but keep in mind the main reason the manufactures are experimenting with it are due to the governement tightening the noose every year for continually stricter emissions compliance.
    Direct injection is a result of that, however it's not without it's share of problems.

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    My CTS4 has a direct injection 3.0 and it is a noisy SOB -- even with all the under hood sound deadening and insulated engine covers it sounds kind of bad.

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    Quote Originally Posted by Naaman View Post
    Sweet. Now, with 95 lbs, is that "overkill" for a bolt-ons application?

    Also, from what limited education I have on the matter, I think I remember testing my fuel system back in school, and it specs out at 58 lbs or some such. But I think this is fuel line pressure, not pressure of the injector itself... do I have that right? The stock LS1 injectors are 28 lbs, correct? (Mine is a 98).

    I'm going to try and get a hold of NicD and see what he thinks and whether there are gains to be had based "merely" on the engineering of the injectors. What I'm assuming this all hinges on is achieving "more complete combustion." If combustion efficiency can be improved, then everything related to combustion should see an improvement... I think...
    Yeah 95# injectors are way overkill on a bolt on application. I have 95# for several reasons, my engine is stroked with a big cam and nice flowing heads through a FAST 102. That alone 95# is still overkill and the main thing is I am using e85 fuel which requires much bigger injectors and fuel pump than regular gasoline does. The only way on a stock cubed and using 93 octane you would need that much of an injector would be if you were FI pushing a good amount of boost. The company I suggested sells all different sizes and they are the same quality just different flow ratings.

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by pajeff02 View Post
    My CTS4 has a direct injection 3.0 and it is a noisy SOB -- even with all the under hood sound deadening and insulated engine covers it sounds kind of bad.
    I hadn't heard they were noisy. I was referring to the cost for instance. Expensive to replace, in some instances removing the cylinder heads to access them. The biggest reason I specifically bought an 05 duramax, since previous years had this issue, and in 05 GM made them accessible through the valve covers (no cylinder head removal).
    I also imagine the fuel pump might be a pricey one if it has to maintain that kind of fuel pressure.

    The other issue that I've heard alot about is carbon build up in the combustion chamber, not good for an injector down there. Cleaning a service is expensive too. I'd be running a crap load of fuel system cleaner through that sucker to avoid any future expensive repairs

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    Senior Member Too Fast's Avatar
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    Yes direct injected engines can be noisey. Those high pressure injectors make some amount of noise. There is all kinds of soundproofing on the engine.

    They do use a standard in-fuel-tank fuel pump like port injected vehicles, the high pressure pump usually is a mechanical unit driven by a lobe on the camshaft. Reminds me of the old school cam-driven fuel pumps.

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    There are companies that can flow match and blueprint your injectors.

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    Senior Member Naaman's Avatar
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    Quote Originally Posted by 35th-ANV-SS View Post
    Those increases can be seen from a tune and happy DYNO alone. Go DYNO the same exact car with the same exact tune on a different DYNO and you'll get different results. Do it on the same DYNO on a different day and you'll get different results. $700+ is a lot to spend on an "experiment" where the same results can be had for $150 (just a tune).


    So what you're saying is, if I tune my car, then "upgrade" injectors and tune it again, I'd see absolutely no difference (or, less than a couple horsepower, if any), between the two tunes. Correct?

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    No. I'm saying the numbers you posted as increases can be seen from a tune alone which makes one suspect how much upgrading injectors really adds. Especially at the cost of injectors.

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