How to scale the HPFP pressure sensor

[Lex]

The reason free revving will result in higher pressures versus being under load is because under load you are flowing a lot of fuel through the motor so the relief valve is not overwhelmed. When you are revving with no load, the engine RPM allows you to build an equally large volume of fuel but you are not injecting any of it resulting in the relief valve having to flow a large volume. The orifice is not large enough for this.

This is why shrinking the orifice of the relief valve is the best approach to fixing the relief valve problem.

Interesting about the dipstick DJ, do you have a compression tester?

[djuosnteisn]

LOL, i was thinking the same thing, no i don't have one, but i can get one after pay day. I've spent too much money lately.

You think my rings are on their way out?

[KoukiS14]

While at DJs today, I took a look at the fuel pressure sensor and relief valve fittings. The sensor fitting is essentially a -4 AN fitting, but the sealing surface appears to be cut at 45* instead of the 37* like a true AN fitting. Although, if you look at the rail itself, it almost looks like it's double cut, with a 45* angle in the middle and possibly a 37* angle outside of that. Just a bit strange.

For the fuel rail, I didn't measure it at all, but it's either 12mm/1.25mm pitch, or possible 12mm/1.0mm pitch. From eyeballing it, I'd say 1.25mm pitch, but I'll have to bring along my thread pitch gauge next time to be sure. It seals with a copper crush washer.

I've never seen a relief valve quite like this. It almost looks like some type of reed valve setup. It's tiny, and doesn't appear at all easy to modify. You might try to restrict flow through it by putting a small piece of welding rod or something just smaller than the inside diameter inside of it. Make sure it's long enough to almost contact the inside of the rail, so that it's doesn't become dislodged and end up floating around inside the rail. Or, just plug it and hope for the best.

[Lex]

Originally Posted by djuosnteisn LOL, i was thinking the same thing, no i don't have one, but i can get one after pay day. I've spent too much money lately. You think my rings are on their way out?

I'm curious to see (as I'm sure you are as well) what your compression is like because it sounds like there's a bit of blowby there. I bought one for under $50 - it doesn't have to be special.

[djuosnteisn]

I'm gonna borrow one from a co-worker today, and hopefully do the test tonight.

I doubt it's a bad pcv valve, cause i have two of them in series essentially, but to be sure i'll check my catch can. If they were bad, the can should be pretty full. I'll also pressure test the intake tract again, cause that'd show if they were stuck open.

If the compression numbers are okay, i guess i'll keep going with testing lol. Just hope it's not a mistake haha.

I also want to order some new plugs and turn the pressure down alot on my wmi pump.

Lex, hit me up on gmail if you have time today.

[Lex]

I started having blow out with meth when the weather got colder. Spray less in the winter.

I may be on and off today, but drop me a line and I should be able to get back to ya.

[aaronc7]

Originally Posted by socks my dip stick didnt blow out? aaronc7's did...

haven't since I took out PTP's "smoking turbo fix"

[djuosnteisn]

Hahaha. Mine just popped up ever so slightly, and there was just a bit of splatter around the bay. Nothing like the shower yours had. I honestly don't think it's all that uncommon, esp with our poor pcv setup, but a compression check certainly won't hurt a thing.

[superskaterxes]

ok so i installed the DJCKT today. i was a lil weary about doing it because i hate soldering in tight places and i was afraid if i fucked something up and needed to put it back i wouldent be able to cause the wires would have been all hacked up. so with a lil ingenuity i came up with this!!!



i took the pins out of the connector and i soldered on the leftover pins i had from testing the Grimmspeed EBCS PnP and VOILA! (dont worry i heat shrinked everything and ziptied it to be pretty) ill tell u at 1/2 turn, the car fucking pulls like a beast. AFR dropped a lil more then a point and i no longer have this shitty studder near redline. i also tested the 2-3 shift studder and its GONE. i needa tweak my ATR map but shit looks silly promising. dustin your my hero

[djuosnteisn]

Okay, here's the compression data and some plug shots:

1 - 157
2 - 153
3 - 141
4 - 152

I cranked each cylinder about 8 times, in 4 crank intervals (poor starter).

I'm at 5500 ft, or roughly 12 psia.

Motor has 23k miles.

It was pretty cold in my garage, like maybe low to mid 60's at the highgest.

1


2


3


4


So i think my compression is pretty good! Cylinder 3 is only one that is a bit off target, but well within tolerance IMO, but by all means lemme know what you guys think.



Some plug shots:



4 & 3 head on:


2 & 1 head on:


1 up close:


2 up close:


3 up close:


4 up close:




And for the ms6 guys, you just have to pull this fuse for to disconnect the fuel injectors:


Oh yeah, i wanted to mention, if you look at plug #1 up close, you can see that the electrode is bent over a bit. Kinda odd. These plugs probably have like 10k miles on them or less.

[superskaterxes]

so wait those compression numbers are ok for your altitude?

FWIW my 1 step colders looked identical to yours when i took em out after 18k.

[socks]

i thought they were supposed to be up around 170?

shocker that 3 is the lowest of the 4.

i wanna check mine :-\

[SpeedSixxx]

LOL u must clean engine bay..looks like a spunked all over it lol

[djuosnteisn]

Na man, with a 10:1 compression ratio (i know ours is 9.5:1, just keeping math simple) 2 psi equates to at least 20 psi difference, so 150 would be 170 at least.


I think these numbers are actually not bad at all.

Originally Posted by SpeedSixxx LOL u must clean engine bay..looks like a spunked all over it lol

I think that spunk is on your computer screen, not my engine bay

[socks]

im gonna test mine soon too

[SpeedSixxx]

Originally Posted by djuosnteisn Na man, with a 10:1 compression ratio (i know ours is 9.5:1, just keeping math simple) 2 psi equates to at least 20 psi difference, so 150 would be 170 at least. I think these numbers are actually not bad at all. I think that spunk is on your computer screen, not my engine bay

LOL bro DJ....i didnt mean ur engine bay homie...i meant whats his name..superskates ....that shit is too dirty and all messy full of wires...

he is a kewl guy but that shit looks messy as all hell...
not u dj..you're a msf god and the spunk is on my hand and key board not screen but ty for the guess =)

[Lex]

Was the engine warmed up? The motor should be warm.

What is up with 3 and always being down on compression compared to the other ones??? This tells me the rings are losing their seal on that one first - more washdown? Meth ends up in #3 only.... hmmm so many thoughts.

[djuosnteisn]

Haha, I guess a rough scalar for 5000 ft is 0.8617, so at sea level, my numbers would be:

1 - 182
2 - 178
3 - 163
4 - 176


Cylinder #3 is the only one concerning, but not too bad considering my measurements before the altitude factor are easily within 15psi... right?

Engine was cold

[Lex]

Originally Posted by djuosnteisn Haha, I guess a rough scalar for 5000 ft is 0.8617, so at sea level, my numbers would be: 1 - 182 2 - 178 3 - 163 4 - 176 Cylinder #3 is the only one concerning, but not too bad considering my measurements before the altitude factor are easily within 15psi... right? Engine was cold

I don't mean to worry anyone but poorer compression can also be a sign of a slightly tweaked rod.

[superskaterxes]

yah plus cold rings arent nearly as sealed as warmed up, expanded rings.

and speedsixx, all those wires are from the DJ CKT u ninny muggins.

[SpeedSixxx]

Originally Posted by superskaterxes yah plus cold rings arent nearly as sealed as warmed up, expanded rings. and speedsixx, all those wires are from the DJ CKT u ninny muggins.

lol...i was juss trying to be funny and i'm always misunderstood..but thats my life so im used to it =)

i love u all =) i just figured out i have 42 hours of vacation time so i'll schedule a couple days off for my install and then i'll actually contribute some info...

[starscream]

I <3 This... Moar Fuel = Moar Boost = Moar Power = Moar Buttsecks = Moar Win = More EVERYTHING! MOAR!

[cpolly69]

or it could have something to do with the fact that the manifold flows the best to 3 - so it's the first to fail

[djuosnteisn]

welp i just bought an evo...














psych.

Okay, car wasn't warmed up in above compression check, so dis regard.

Here's a proper test:
DISI Compression Results

[socks]

Originally Posted by Lex Was the engine warmed up? The motor should be warm. What is up with 3 and always being down on compression compared to the other ones??? This tells me the rings are losing their seal on that one first - more washdown? Meth ends up in #3 only.... hmmm so many thoughts.

#3 showed more leak down on subparpunk's car.

Its not likely a bent rod in his case, its likely the rings. Even so, not much to worry about now.

#3 runs hotter, we know that from the MAP flow bench on the IM. although, the same applies, if your spraying meth, if #3 gets more air, it also gets more meth.

[cpolly69]

or is it #3 that has the metal in the way in the im and runs richer - i am always getting those confused - i know cyl #1 is one extreme and #3 is the other ....

[djuosnteisn]

#1 is farthest to passenger side.

#4 is driver's side, and has super glom blob to hold the vcts flappers in place. I think as far as "flow" goes, it flows the worst.

[cpolly69]

i'm just going off of flow testing discussed in other threads and i don't think it's a coincidence that #3 flows the best and sees more compression leak -
i wish i could just say - yeah i bought an evo...

[djuosnteisn]

So i'm gonna try to come up with a restrictor pill or something for the relief valve soon.

I found this flow calculator one line:
Flowrate Calculation for an Orifice Flowmeter

And used this site to get fluid density for gasoline:
Fluid Properties

And plugged in these values:
pipe inlet diameter: 0.5 inch
Orifice diameter (the pill): 0.05 inch
Pressure differential across orifice: 2000psi
Fluid density: 680 kg/m^3
Flow coefficient: 0.7

And i get a volumetric flow rate of 0.0472 gal/s

Would 50 thousandths be small enough?

[socks]

here are the intake manifold flow characteristics

Manifold _____Runner 1_____ Runner 2_____ Runner 3_____ Runner 4_____ % of Imbalance _____Total CFM
Stock _________218 __________258_________ 273 _________227___________ 25.23% __________976
MAP Modified___ 258 __________273 _________258_________ 251 ____________5.81 ___________1073
Percent Increase 18.35% ______5.81% _____-6.49%_______ 10.57% ________333.94%

Avg. Net Increase ___ 7.31%

[bf360]

Originally Posted by socks here are the intake manifold flow characteristics Manifold _____Runner 1_____ Runner 2_____ Runner 3_____ Runner 4_____ % of Imbalance _____Total CFM Stock _________218 __________258_________ 273 _________227___________ 25.23% __________976 MAP Modified___ 258 __________273 _________258_________ 251 ____________5.81 ___________1073 Percent Increase 18.35% ______5.81% _____-6.49%_______ 10.57% ________333.94% Avg. Net Increase ___ 7.31%

do you actually have the map manifold?

[socks]

No, subparpunk does, he's local to me. I helped him install it.

[djuosnteisn]

Steal it from him and send it to me

[superskaterxes]

so wait,

how do you loose flow to runner 3? is it just cause the other runners are now flowing better and stealing air from that runner? and where did most of the imbalance come from? if ron did my mani and did most of the runners and what he could reach was that where the problem existed or did u need to cut it in half to get to the real problem areas.

[djuosnteisn]

MAP offers two separate services, one where they cut the mani in half, and one where they port what they can reach.

I believe the above data is for the one they cut in half, off phil's motor right?

[bf360]

you loose flow because the other runners are getting more equal flow

[socks]

it is absolutely amazing the work they did on that manifold.

[spnkr21]

No, false. I believe they cleared this up already and it was a typo
It's supposed to be:
----Runner 2 - Runner 3
stock 258 273
MAP 258 273

And as far as whoosh's manifold. I dont think cutting it open really does anything. I think whoosh was supposed to get his flow checked, maybe you could PM him for the results.

Oh and the price tag on that MAP mani is rediculous

[Lex]

5 thou is probably much too small. Might as well plug it up at that size. I would reduce it to 0.25-0.5 of its original diameter if you want to retain the safety factor at all.

Originally Posted by djuosnteisn So i'm gonna try to come up with a restrictor pill or something for the relief valve soon. I found this flow calculator one line: Flowrate Calculation for an Orifice Flowmeter And used this site to get fluid density for gasoline: Fluid Properties And plugged in these values: pipe inlet diameter: 0.5 inch Orifice diameter (the pill): 0.05 inch Pressure differential across orifice: 2000psi Fluid density: 680 kg/m^3 Flow coefficient: 0.7 And i get a volumetric flow rate of 0.0472 gal/s Would 50 thousandths be small enough?

[KoukiS14]

Dustin, I don't think you necessarily care about the flow rate, but rather the orifice size needed to maintain a specific pressure on the rail side. Maybe this will help. Also, neither of those calculators consider the fact that there's a sprung pressure relief valve in place already.