[jd2021]

Hello All,
Hope you're doing well today. As the title states, I am trying to figure out how port injection allows for more fuel availability. I understand how PI works, as in you get an extra set of fuel injectors on the intake ports, but how does it add more fuel if your fuel system is already limited on DI? How is more fuel available to be driven to the PI fuel injectors with the same pump? Just curious is all.

Best,
J

[KingLT1]

Basically, you lean out the DI side so the IPW's are in range, then add back the fuel needed on the PI side to hit desired AFR target. You need enough injector on the PI side to compensate for leaning out the DI side and being able to add additional fuel on top if power is increased further. It's a non-issue because even a set of 60lb PI injectors on top of the DI will support quite a bit of power even on full E85.

[jd2021]

Originally Posted by KingLT1

Basically, you lean out the DI side so the IPW's are in range, then add back the fuel needed on the PI side to hit desired AFR target. You need enough injector on the PI side to compensate for leaning out the DI side and being able to add additional fuel on top if power is increased further. It's a non-issue because even a set of 60lb PI injectors on top of the DI will support quite a bit of power even on full E85.

So just out of curiosity, if you're targeting higher power with full e and boost, do you still have to lean out the DI side?

Also, I understand that there's only really 2 options to upgrade DI injectors on the LT1 fuel side (LT4 and 30%+), but theoretically if we had more injector options would just adding bigger injectors to DI work?

I guess I am trying to wrap my smooth brain around how adding PI to an LT1 fuel system will allow you to safely run more power without tapping out the high side LT1 fuel system if it already gets tapped out solely on DI, as in why people upgrade to LT4 fueling for boost if the LT1 fuel system on PI can produce more power just with more injector, which makes my brain think that you would just need to upgrade injector to get more power for DI only instead of having to upgrade the HPFP and injectors.

[ste6000]

Originally Posted by jd2021

Hello All,
Hope you're doing well today. As the title states, I am trying to figure out how port injection allows for more fuel availability. I understand how PI works, as in you get an extra set of fuel injectors on the intake ports, but how does it add more fuel if your fuel system is already limited on DI? How is more fuel available to be driven to the PI fuel injectors with the same pump? Just curious is all.

Best,
J

nice little video that might help explain it some.

[Katech_Mike]

Originally Posted by jd2021

So just out of curiosity, if you're targeting higher power with full e and boost, do you still have to lean out the DI side?

Also, I understand that there's only really 2 options to upgrade DI injectors on the LT1 fuel side (LT4 and 30%+), but theoretically if we had more injector options would just adding bigger injectors to DI work?

I guess I am trying to wrap my smooth brain around how adding PI to an LT1 fuel system will allow you to safely run more power without tapping out the high side LT1 fuel system if it already gets tapped out solely on DI, as in why people upgrade to LT4 fueling for boost if the LT1 fuel system on PI can produce more power just with more injector, which makes my brain think that you would just need to upgrade injector to get more power for DI only instead of having to upgrade the HPFP and injectors.

It's exactly how KingLT1 described.

You target a safe injector pulse width and/or pump angle on the DI side and you use PI to add the additional fuel needed to hit your target AFR.

[laynlo15]

The real big deal is the amount of HP you can gain running E85 on a stock Lt1 fuel system. For example my 2016 1 SS with a 2300 Maggie made 550 hp on 93 octane, we ran our best of 10.82@130. No tuning to the trans on that car, now that was with a drag pack. Go ahead 5 years, I bought a 2022 Lt1 Camaro, ran it NA for a while and then ran across a 2300 Maggie (used from Superchargersonline). I let Mike know at TooHighPsi and he wanted to do the Port Injection on mine with the new reflex controller. We got it all setup and ran our first pass 10.34@135 on 8 psi of boost. That setup made 632/559 rwhp, we stepped up to a smaller pulley and made 707/669 rwhp and ran 9.80@142.96 on 10.5 to 11 psi of boost. So, adding the port and E85 allowed us to make 157 more rwhp with no other mods except a JMS boost a pump. Both cars had only a RotoFab CAI. The 2022 did have a drag pack for the 9.80 run. We ran the 10.34 on a Nitto drag radial on stock 9.5 GM 20" wheels. So, the benefits are obviously evident in my two comparisons.

[Megahurtz]

Port Injection uses much lower fuel pressures and is fed from your low side pump only. DI must have very high pressures and must be fed from the high side pump(which is also fed from the low side).

So you lower the fuel delivery on the DI side which keeps the high side pump happy and reduces the load on the low side pump. Then you spray the port injectors using the low side pump pressures. Same way the Corvette ZR1 does it.

I've tuned a few Too High PSI port cars already. It works really well. I'm waiting for the DSX kit for my personal car so that I don't have to tune a separate controller. I've also tuned quite a few cars with the LPE Big Bore and XDI Injectors. Both are viable paths to make a lot of power considering the goals and mods. Without a cam, the port setup has a much higher ceiling than the DI stuff.

[cjperformance]

Originally Posted by jd2021

I guess I am trying to wrap my smooth brain around how adding PI to an LT1 fuel system will allow you to safely run more power without tapping out the high side LT1 fuel system if it already gets tapped out solely on DI

If i understand this part of the question correctly.... the PI runs on low side pressure, not fed by hpfp. So increasing the capacity of your low side may be required, but burden will be less on high side due to lowering the demand on DI.

[laynlo15]

So my 2022 Camaro was running about 74 psi on the low side on E65 and 2500 or so on the high side. When did the port and got to 11 lbs Mike (Thpsi) dropped the low side to about 60 psi and the high side to about about 2200 psi. There is less stress on the DI with the port, doesn't have to work as hard as the PI is running 30 percent of the fuel and the DI is 70 percent instead of 100 percent without PI. This allows an Lt1 with the stock fuel system to run a boosted application without spending thousands on upgraded fuel systems such as converting the DI to Lt4 HPFP and Injectors. Obviously it would be better to run a low side upgrade such as Katech's. We had enough fuel where I could have run more than 11 psi off boost and could have probably made 730 on the stock fuel system, but we are dealing with an Lt1 with 11.5 compression and cast pistons. Believe me I know what high boost does to an Lt1. I think you know what I'm talking about. So, in a nutshell DI is worth every penny you spend on it for making good clean rwhp on E85 with a boosted application.

[GAOLDGUY]

Originally Posted by laynlo15

So my 2022 Camaro was running about 74 psi on the low side on E65 and 2500 or so on the high side. When did the port and got to 11 lbs Mike (Thpsi) dropped the low side to about 60 psi and the high side to about about 2200 psi. There is less stress on the DI with the port, doesn't have to work as hard as the PI is running 30 percent of the fuel and the DI is 70 percent instead of 100 percent without PI. This allows an Lt1 with the stock fuel system to run a boosted application without spending thousands on upgraded fuel systems such as converting the DI to Lt4 HPFP and Injectors. Obviously it would be better to run a low side upgrade such as Katech's. We had enough fuel where I could have run more than 11 psi off boost and could have probably made 730 on the stock fuel system, but we are dealing with an Lt1 with 11.5 compression and cast pistons. Believe me I know what high boost does to an Lt1. I think you know what I'm talking about. So, in a nutshell DI is worth every penny you spend on it for making good clean rwhp on E85 with a boosted application.

The reasons above are why I think your last build is one of the best for high reliability and reasonable HP. I somewhat feel that if I had, (1) a Maggy, (2) Port Injection, (3) Front Crank Seal + The Larger Vent Hose that Jannetty promotes, (4) Extra Booster for low pressure side, I could be content not to not have any other engine mods.

[laynlo15]

Originally Posted by GAOLDGUY

The reasons above are why I think your last build is one of the best for high reliability and reasonable HP. I somewhat feel that if I had, (1) a Maggy, (2) Port Injection, (3) Front Crank Seal + The Larger Vent Hose that Jannetty promotes, (4) Extra Booster for low pressure side, I could be content not to not have any other engine mods.

I would totally agree, remember I ran the larger crank hoses way back in 2018. But it was too late to save the first engine, we actually changed the hoses in the staging lanes at the 2018 Camaro Fest as Mike had brought with him from California after he'd figured out that they worked so well on his own C7 Z06. I had already pushed the front seal out of the 16ss, that's when he started working on the larger hoses. The hoses are easy to change for anyone wanting to try them, they work.

[jd2021]

Originally Posted by Megahurtz

Port Injection uses much lower fuel pressures and is fed from your low side pump only. DI must have very high pressures and must be fed from the high side pump(which is also fed from the low side).

So you lower the fuel delivery on the DI side which keeps the high side pump happy and reduces the load on the low side pump. Then you spray the port injectors using the low side pump pressures. Same way the Corvette ZR1 does it.

I've tuned a few Too High PSI port cars already. It works really well. I'm waiting for the DSX kit for my personal car so that I don't have to tune a separate controller. I've also tuned quite a few cars with the LPE Big Bore and XDI Injectors. Both are viable paths to make a lot of power considering the goals and mods. Without a cam, the port setup has a much higher ceiling than the DI stuff.

Ahh yeah that explains it. I didn't know PI ran off of low side. Makes sense now .

[laynlo15]

Yes, DI and Port get the fuel from the same source. I guess you could say it's divided up into two portions, the PI gets about 30% as it comes thru the fuel rails and the DI gets it right after the FF sensor when it enters the HPFP. I guess you could say the DI doesn't have to work as hard as the PI takes up some of the burden on the DI. It's a miracle. Right? Best thing since Pepper Jack Cheese.

[Black16]

I have a question about fuelling. If all that is available is 93 octane what would you advise for say a 2650R on a stock motor setup.

Thanks in advance for your answers.