12ht faster on boost fuel delivery, full boost quicker (1 Viewer)

[MCJakeCrim]

After replacing all my vacuum system on my 12ht, i experimented with the boost pressure delivery to the on boost fuel aneroid.
i replaced the yellow T valve between the manifold boost supply and on boost aneroid and boost light solenoid lines with a straight through vacuum T fitting.
The yellow factory T fitting meters boost to the fuel aneroid via restriction through the aneroid T fitting side.
Not sure if this has been done or talked about.
But i get faster maximum boost (about 100 rpms sooner) also fuel delivery from the on boost system hits faster and harder where i can noticeably tell. it just rips harder faster.
has anyone played with this? would like someone else to try it out and see if im just feeling a "placebo effect".
i have 3 inch exhuast, EGT, Manul boost controller, 5 speed, pyro and boost gauge running 12 lbs boost.
wouldnt recommend trying without pyro and boost gauge, larger exhaust, as EGTs climb faster in the higher rpms.
i dont believe this allows anymore fuel than the pump is capable delivering, i think it just allows the aneroid to meter a larger volume delivery faster and more responsive.
thoughts?

 

[MCJakeCrim]

bumping,
anyone game for trying this out and posting feedback?

 

[FordPrefect]

I had a look at mine but I'm unsure which yellow t piece
Thanks

 

[MCJakeCrim]

Fordprefect,
ill post some pics tomorrow after i get off work.

 

[FordPrefect]

Thanks
Alex

 

[davegonz]

Any chance that you tell me the ID of the hose/tubing on the aneroid and wastegate?

 

[MCJakeCrim]

the T fitting that has the restricter in it is
90413-04004
the tubing is generic 4mm tubing, so the part id is the same for all Vac tubing.
if you look at the intake manifold where it connects to the shutoff butterfly valve follow the boost vacuum line off the manifold, it connects to a small filter then runs into the said T fitting. the fitting splits the vacuum to the on boost fuel aneroid (restricted) and the other vacuum line gets split off to your low and high boost pressure solenoids (green and red turbo pressure lights).
i refer to these lines as vacuum, but they are actually flowing boost pressure, but the lines are found in the vacuum diagram.
Ive been consulting with Tim Law from AUS, this is a common setup for guys running Gturbos or modified turbos, as they actually put their boost controller in the loop there. feeding boost and controlling boost closer to the aneroid.

 

[MCJakeCrim]

 

[MCJakeCrim]

robbed from another member of Mud ^^

 

[MCJakeCrim]

 

[MCJakeCrim]

my setup before i removed the T fitting and replaced all my vacuum lines.

 

[MCJakeCrim]

the lines firm the manifold are red. zoom in to the pic and youll see the yellow fitting im talking about.

 

[MCJakeCrim]

my setup is a little difdernt than a HJ. i have a FJ60 12ht conversion. so no boost lights in my dash so i dont run boost from the manifold to anywhere but my boost gauge and fuel aneroid.

 

[Feistl]

So what do we reckon the restrictor is for?

Is that to just smooth out any spikes in boost and stop the pump from having to adjust wildly?

I am in the process of rebuilding a 12ht and was planning on running a dedicated line from the intake manifold direct to the pump for maximum responsiveness, however I don't want to damage the pump...

Cheers

 

[MCJakeCrim]

I believe the restrictor slow and meter boost pressure to the aneroid diaphram, as it controls amount of boost signal pressure to your "on boost maximum fuel" delivery system within the IP.
when you remove this restrictive t fitting ive noticed i get a more responsive on boost fuel delivery.
what havale also notice is a small degradation in fuel economy, about 10-20 less miles per gallon every 10 gallons.
i also notice that when i drop off throttle and drop boost pressure it reponds faster with no boost fuel also when decelerating, and have also noticed i get the slight, small common idle rpm dip at the bottom of rpms when coming to idle. This T fitting may be a part that helps keep throttle stable at the bottom and not dip. but... im going to put the T fitting back into the system to see if this is actually what its doing (and check my paranoia). if it is indeed this T fitting that assist with throttle dip by holding boost fuel pressure for longer and more stable, i may setup a custom boost pressure system with check valves that allow for faster maximum boost pressure but restricts and slows down the pressure release side. out of town for the weekend, but ill post results when i return the fitting to original setup and so forth.
i dont think taking the T fitting out will damage your aneroid or pump, as lots of guys are running high boost with modified custom turbos and no t fitting.

 

[FordPrefect]

I gave it a try but I have retuned to the yellow valve,
I have an auto and did not notice much difference.
I think it brought on some early black smoke under heavy acceleration.
But it really did not feel much different.
I think the converter probably absorbs any small rpm boost changes.
Regards
Alex

 

[MCJakeCrim]

ok. great. thanks for the feedback.
i havent had time to fiddle with it. but ill probably get back at it next week.
i still eant to put the yellow t back in and see the difference.

 

[MCJakeCrim]

Alex,

Are you running higher boost or aftermarket exhuast, etc?

 

[FordPrefect]

No standard

 

[Jentuh]

I thought the pressure line on the crossover pipe was only there for the tubo indicator on the rpm gauge.
I plugged it when I installed my intercooler, and had to take the crossover pipe off.

No that I see this, I'll need to rethink this and find a spot to get this pressure signal I guess?