Fuel line mod for fk8

[Fk8_tuning_development]

This isn’t something new but I couldn’t find any data on this mod on an fk8. So I tested it running hondata. I do know accord owners did do this already. I have heard motec fk8 owners have tested this but couldn’t find anyone on hondata. The oem fuel line from the high pressure pump to the fuel rail has an extremely small outlet. The side coming out of the pump is far smaller. In fact less than. 1/16th if an inch.
Here’s a pic after drilled has to put the before pic and initial pic cause page would not cooperate. Kept throwing it to the bottom.

You can see in the last pic I added a recessed taper and a top taper. The actual hole diameter was increased to 1/16tg of an inch. Test results show it’s 5 percent more fuel from 5000 to 7000 rpm with less pressure loss than non modded line. Many of you already know the Fk8 even though the pump duty cycle isn’t maxed out drops up to 200 psi above 4500 rpm.
I added the recessed taper cause after it was drilled the fluid had a tendency to spray a bit instead of flowing right through. The recessed taper was done with 5/64 but abs the top with a 50 degree countersink but. Then sanded off the rough edging with 1000 grit. then 1500.
Here’s a pic if two different e25 logs.
First is one that doesn’t have fuel line mod.
Both logs had super close fuel pressure and sane exact 12.4 afr and rpm super close.

although it’s 2 different cars both are full bolt on Prl intake with Mishimoto and Prl intercoolers

you can see with the modded line more fuel cause 20 percent aircharge increase and less duty cycle.
it was extremely hard to find a matching rpm with exactly 12.4 aircharge on e25 tunes. It’s not commanded 12.4 it’s actual 12.4 cause commanded means nothing if the car doesn’t hit the target fuel. The first log is not from my car it’s a person who had problems that I had to fix his tune.
The fuel pressure drop is usually less but the modded line car was spinning in 3rd on above the highlighted rpm point.

when traction is solid fuel pressure looks like this with modded line. 100-125 psi loss but better than 200. You can see fuel spiking is not an issue.
Airway done 1500 miles and many different fuels variations.
93
93 plus 500cc meth.
E12 no meth
E12 plus 500c meth
E25 no meth
Renegade e85 race fuel was basis for testing due to it’s consistency and cause the nearest e85 pump is 60 miles.

I personally purchased a new line just in case the ecu didn’t function with the mod. The line will cost between 200 and 300 depending on where you get it. It’s shown as discontinued on Honda parts sights but it is absolutely NOT discontinued.

Yes fuel pulsation is a possible risk but a few accord guys are running bigger 5/64 hole no issues. Going too big can actually cause pressure loss. I’ve found no issues with fueling pressure fuel pulsations or any codes. Started right up.
The mod is involved I suggest you have higher level experience. If you’ve never pulled an i intake manifold off this mod isn’t for you.

if you want to try it I suggest you follow radium port injection for most of the removal. You will still need to remove solenoids and brackets to get to the line. You can NOT sneak it out like accord fuel line mod video the lines and pump are different.

You will need to get the 3 circled items out of the way. The right circle is pointing a bracket on the back of the head and the arrow points to a bracket behind the wire loom.
It takes about 3 hours for a skilled Individual not including drilling the line. If you snap a bit off in the line you’ll ruin it cause you can’t drill it out. Also use a new clean drill bit and don’t push to hard if you cut to fast it will be rough reducing fuel flow.
This mod will not help your current tune you must tune to see hp gains. I may very likely throw it back on the dyno to test hp limits with fuel mod. I’m very busy lately so if I don’t answer right away sorry.
I’m also on Instagram fk8_tuning_development
Email [email protected]
Inquiries are best through the email including custom tunes and dyno tunes. I’m in Myrtle beach SC area for dyno tuning.

heres a pic of most of what needs to be removed.

Before and after just 1/16th hole .

 

[Fk8_tuning_development]

Update I went to a 5/64 hole and I’m testing e25 at significantly higher aircharge than before. It’s as far as I’m willing to go in size cause any larger will risk pressure control issues. I have not had time to put it back on the dyno. The speeds required for traction are far beyond what I can do safely on the street. Fuel gains are about 7 percent just from modifying the line. It does not require any special tuning but there are a few adjustments that will get you more power at high rpm with no changes to fuel, cam timing or ignition timing. One significant benefit to better pressure at high rpm is shorter injector open time. This helps give the fuel more time to atomize and better burn.
here is a pic of the increase in size.I added taper again for same reason as before. I talked to an engineer about this. He has seen logs from TCR car and believes they are likely doing this.

I was mostly certain that the new xdi pump for the civic type r was the evo version. Not Mitsubishi evo just the design xdi calls evo.
I figured I’d ask anyway to be 100 percent.
With me 1 percent of doubt will drive me crazy. I got a response from an engineer that even after you buy an xdi pump for fk8 that one mod besides injectors was still needed. He’s an engineer for a big company. The company he works for deal in race cars only including rally circuit and sell not just motec ecu but everything from harnesses and so on. I prefer not to give his name cause he was kind enough to share valuable information and I don’t want him getting random messages. He’s a busy person and if you have any questions I’ll gladly ask him myself.
here’s a photo of the message.

Do not raise the fuel pressure on your car this will shorten the life of your high pressure fuel pump. I am testing this at my own risk.
The higher rail presure is cause of an issue with direct injection spraying too long and not allowing full fuel atomization. I suspect based upon the information the tcr most likely makes more power than the 340 states in articles I’ve read. The stock fuel system doesn’t need to be modified for 340 hp.
Thanks for reading message about tunes or questions at the email.
fk8,tuning.development @gmail
Follow me Instagram fk8_tuning_development.

 

[turbociv910]

interesting stuff. I wish the hondata could log proportional and integral of the pump control. Would show what its really doing. I would test this, but like you said, not a quick job and juice isnt worth the squeeze for me.

The higher rail presure is cause of an issue with direct injection spraying too long and not allowing full fuel atomization.

i do believe you mean your injection even is lasting too long and intersecting with your ignition event? have you done the calculation to see how much of your injection window you are using? I wouldn't blame this on poor atomization, as a 2900 psi system is probably the best atomization we (honda guys) have ever seen.. i bet running Ethaol with no port injection will make your injection too long.. when i get home ill share a excel file i made to easily see your injection limit

I know with my shitty q300 muffler, i had to move injection timing to 345 because the oem was too much back pressure and heat not leaving the cylinder, causing it to pick up slight knock after 5000 (where it goes to 360 injection time). only injecting fuel with the valve closed during that time allowed me to run more timing.

 

[turbociv910]

enter your info in and see where youre at

 

[ebatr24]

This is interesting stuff, if this mod can provide a little bit of added headroom I would be all over it. I have an FK8 with a crappy HPFP, my car tapped out really quick just FBO. (quicker than other FK8s) I don't have the finesse or experience to drill out my line though without potentially messing it up. You should consider selling these, I'd be a customer.

 

[elmerzasty]

enter your info in and see where youre at

Very cool of you to share the spreadsheet, however I think you would have to take cam specs (durations) into account to determine when valves close/open.

 

[Fk8_tuning_development]

interesting stuff. I wish the hondata could log proportional and integral of the pump control. Would show what its really doing. I would test this, but like you said, not a quick job and juice isnt worth the squeeze for me.



i do believe you mean your injection even is lasting too long and intersecting with your ignition event? have you done the calculation to see how much of your injection window you are using? I wouldn't blame this on poor atomization, as a 2900 psi system is probably the best atomization we (honda guys) have ever seen.. i bet running Ethaol with no port injection will make your injection too long.. when i get home ill share a excel file i made to easily see your injection limit

I know with my shitty q300 muffler, i had to move injection timing to 345 because the oem was too much back pressure and heat not leaving the cylinder, causing it to pick up slight knock after 5000 (where it goes to 360 injection time). only injecting fuel with the valve closed during that time allowed me to run more timing.

Well running motec helps you see those things I have to watch for sudden lean or Increased injector duty cycle. You can also alter spray timing in motec so that it can automatically advance spray to not run into spark.

I had more power moving exhaust cam a few degrees retard but after that I needed to put it back in. This was to be able to move injector timing at higher rpm to get more power. At least running a richer mixture using a basemap as a test bed for increased fuel volume. Running 11.8 at 4000-4500 rpm with pressure drop will run into spark.

I was able to get 17 degrees ignition up at high rpm no indication of fuel into spark running my mixtures. Of course this was my tune not hondata basemap. Any more timing was useless even with no knock.

Again using basemap as test bed. Running a higher pressure at upper rpm still left the fuel pump below 90 percent. Note the e25 basemap is NOT meant to be run on a full bolt on car as it will normally lose too much fuel pressure.

As you know higher pressure increases pump duty cycle but lowers injector duty cycle. The hondata e25 basemap leaves injectors open too long on a fbo car with the rich 11.47. Normally fbo cars see misfire around 4500 and clears up. Instead of running into low rpm too much iniector open I literally had the opposite problem.
At high rpm it ran into spark. Gap was plenty sufficient at .022. Bumping the pressure solved this.

A bit of moving the SOI allowed more timing that actually made more power running a richer mixture. Only because allowing more time to atomize.
after a lot testing the line mod on e25 I threw methanol at it.
500cc of straight methanol is a lot for a stock turbo fk8. I add some water running 750cc and I don’t spray 100 percent.

After adding about 650cc of methanol the cars injector duty cycle is literally about 22-23 percent. Trims are maxed out and unable to go any further. I could add more than 18 degrees timing right now but there’s no more power doing this on stock turbo. Right now I’m waiting for a g25-660 kit from full race.

So I know the first thing I’m going to hear from someone is why not run 1000cc??
read below.

You can run 1000cc of methanol if you enjoy putting your car into a danger areas by playing with MAF scaling and/or fuel offset. 750cc can flood it. This is 100 percent the WRONG way to do this. I’m not going to mention who does it but just to make numbers this is dangerous way to tune. The ecu may correct fuel to a point but it’s not instant. Just cause you are hitting afr doesnt mean you have fuel pressure. I’ve seen logs with 1000 psi presure drop. That’s not a typo.
It’s counter productive cause the terrible fuel spray reads as knock running into spark. On the street the engine will have more load compared to most dynos.
Most likely full on detonations are occurring with 27 psi and a seriously poor spray and mixture.
1000cc can literally flood a stock turbo fk8 to the point of misfire. Misfire at high loads is very dangerous.
The right way is a way to find more
NON-SUPPLEMENTAL FUEL.

I run some water because even though the meth can cool it can all burn. Water is inert and does not produce any extra heat and solely absorbs it. I’m not adding more btu back into the equation

Think about this when you want to break stock turbo records. Do you want a car that could blow up on a power level that it normally could easily handle??

Merry Christmas. Happy tuning and modding any questions
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[shadow]

Did you drill out both the inlet and outlet sides of the fuel line? Also, could you show me where you got the 50 degree counter sinking bit? Most of what I see online are of the following angles:

Thanks.

 

[elmerzasty]

You only drill the outlet, the inlet is of full line diameter.

 

[WhiskeyTango]

Did you drill out both the inlet and outlet sides of the fuel line? Also, could you show me where you got the 50 degree counter sinking bit? Most of what I see online are of the following angles:

Thanks.

Google took all of about 10 seconds to find an 1/8"

https://www.carbideanddiamondtoolin...luded-Angle-HSS-.125-3-INCH-Diameter-ID-3226-

 

[shadow]

Google took all of about 10 seconds to find an 1/8"

https://www.carbideanddiamondtoolin...luded-Angle-HSS-.125-3-INCH-Diameter-ID-3226-

I saw that too, but was wondering if the 50 degrees mentioned by the OP was the centerline angle or included angle.

So I guess it is a 50 degree centerline which is equivalent to a 100 degree included angle.

Thanks.

 

[BrokeCTROwner]

Who can I pay to get this done for me

 

[ebatr24]

Who can I pay to get this done for me

I will have a spare line once I throw mine in tomorrow, if you want to get one.

 

[BrokeCTROwner]

I will have a spare line once I throw mine in tomorrow, if you want to get one.

I’m assuming it’s an undrilled line correct? Did you drill this new line yourself?

 

[ebatr24]

I’m assuming it’s an undrilled line correct? Did you drill this new line yourself?

Correct, I had a modded one that I am going to throw on tomorrow. I intended to have it installed when I installed my XDI pump but ended up not doing so at that time due to time constraints. Once I swap my stock unmodded one out, I will have a spare.

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