[Vrodviddy]

Just curious if anyone has notice gains upgrading fuel system to lt4. It will be my next upgrade.

[grampa_ss]

I'd say zero as it's a supporting mod for when you're above 600RWHP or so and your engine wants more fuel than the stock fuel system can provide. This is an assumption based on reading this forum. So if i'm wrong...blame them.

[GuywithL86]

Your engine needs so much fuel with so much air. So unless your at the limits of your stock fueling it will not help you.

[Vrodviddy]

Originally Posted by GuywithL86

Your engine needs so much fuel with so much air. So unless your at the limits of your stock fueling it will not help you.

I short handed and left the details out cause i am at work and got pulled away. lol.

Anyways. I have stage 3 cam 235/239 with 32% fuel lobe. I have noticed that i am not getting enough fuel.. spark plugs are are lightly brown so tells me running on the lean side. So fuel upgrades will be next. Now the question i meant to ask. lol. Tsp claims 110 hp gain. Well my tune only got 65 hp. But i think i am leaving some gains on the table cause engine not getting the fuel it needs. Has anyone had this problem and.. if so when corrected were you able to reach those claimed numbers?

thanks. and sorry for the misleading question.

[Dads1le]

Just upgraded my stage 1 h/c build with lt4 injectors (already had low side pump as it’s a 1le). Last dyno was about a year an 4 months ago at same shop that installed the injectors
Net peak hp difference was -3 hp loss 557 now vs 560 before and peak torque is same at 500 but... there was a big torque bump on the low end averaging about 10 ft lbs from 2500 up to 5250 cross and averaged around 5 hp bump along the entire curve. If you pm your email I can send dyno chart to you. Don’t know how to post pics on here
Drivability is much better now Really jumps at low rpm

[Vrodviddy]

Originally Posted by Dads1le

Just upgraded my stage 1 h/c build with lt4 injectors (already had low side pump as it’s a 1le). Last dyno was about a year an 4 months ago at same shop that installed the injectors
Net peak hp difference was -3 hp loss 557 now vs 560 before and peak torque is same at 500 but... there was a big torque bump on the low end averaging about 10 ft lbs from 2500 up to 5250 cross and averaged around 5 hp bump along the entire curve. If you pm your email I can send dyno chart to you. Don’t know how to post pics on here
Drivability is much better now Really jumps at low rpm

Ok. See that's what's what I heard and looking for. Need more take off power. All the upgrades I did.. while a little better. Not what I hoped for. Want more power off the line. Besides super charger I'm thinking this the only other thing for more low end power.

[Dads1le]

For me was noticeable difference for sure. The other thing that made it feel noticeably more peppy on the low end was my 19 inch apex race wheels. They look
Like ass but but about 6lbs lighter let corner and you can feel it
Also would do ati underdrive pulley if you haven’t. All the little things add up

[s346k]

i highly doubt the car needs any fuel system upgrades. are you using gasoline only? what’s the injector duty cycle, fuel pressure, and afr on a wot pull?

stop trying to read plugs on a fuel injected car and judge the available fuel. that’s not how it works.

[Joshinator99]

Originally Posted by s346k

i highly doubt the car needs any fuel system upgrades. are you using gasoline only? what’s the injector duty cycle, fuel pressure, and afr on a wot pull?

stop trying to read plugs on a fuel injected car and judge the available fuel. that’s not how it works.

Good points. Low side fuel pressure, high side rail pressure, and injector pulse width will tell you if your fuel system is keeping up. Look at commanded values and see if you’re getting there.

[MP3BOOSTED]

Their ratings are at crank not whp for TSP vvt3 cam

[Vrodviddy]

Originally Posted by s346k

i highly doubt the car needs any fuel system upgrades. are you using gasoline only? what’s the injector duty cycle, fuel pressure, and afr on a wot pull?

stop trying to read plugs on a fuel injected car and judge the available fuel. that’s not how it works.

I am running 93 right now, but going back for another tune for e85. I'm going to talk to my tuner and see what he thinks. I don't have hp tuners. Just noticed the spark plugs a tad on brown side, so figured that engine running lean. But that i guess could be addressed when i go back for a tune.

[Dads1le]

First try at posting a pic Red line is current with lt4 injectors added. Blue line is after adding prays ported msd a year and 4 months ago. Orange line is prays ported stock Intake.
This is on a 17 1le with prays h/c stage 1 ported msd. Milled ported heads. Underdrive pulley. E85. 17/8 arh to borla s type

[wnta1ss]

Originally Posted by Vrodviddy

Just curious if anyone has notice gains upgrading fuel system to lt4. It will be my next upgrade.

LT4 fuel parts by themselves do not add torque or horsepower. They are only useful if your current fuel system is not keeping up and you have the ability to run the engine harder if fuel supply allows, like having a supercharger for example.

[TJay74]

Originally Posted by s346k

i highly doubt the car needs any fuel system upgrades. are you using gasoline only? what’s the injector duty cycle, fuel pressure, and afr on a wot pull?

stop trying to read plugs on a fuel injected car and judge the available fuel. that’s not how it works.

I am gonna disagree, vast majority of the cars that are modded will need some sort of fuel system upgrades. Injector duty cycle and low side / high side fuel pressures will dictate this more than anything else.

Until the OP logs the injector duty cycle, low side FP and high side fuel pressure it will be a guess if he needs anything else. E85 will only make this problem worse due to the extra 30% fuel needs.

As said though to the OP, the fuel system will not in itself gain you any power, it will give you more headroom to be able to make more stable power and not take a chance of going lean and blowing the engine up.

You current and future power goals will dictate this more than anything else, without those no one can really comment. The 32% lobe on that cam only helps the high side of the pressure feeding the fuel pump under the intake (HPFP). It does nothing for the low side which is the pump in the tank (LPFP).

If money isnt an issue and you have time on your hands then I will say sure, go ahead and drop in the LT4 LPFP, HPFP and the LT4 non restricted fed pipe for the HPFP and the revised cross over fuel lines for the fuel rails. At least at that point you will know that you can support near 700rwhp with no worries.