Where should I tap in for Boost gauge?

[nocwage]

I've got a 1988 Silvia K up here in Ontario and I just got a boost gauge for it. Which line should I tap with a T-connector to get the pressure?Obviously there are a few to chose from, what was your preference?(CA18DET)

[Ghettokracker71]

What you want to do,is ship the car to richmond,Va. Then wait until your next project, a KA powered 240sx is shipped to you as a trade:D

[nocwage]

Sounds fair enough to me!

Does it matter that my car already has 79,000km on it? The speedo also only has km, no miles since it's JDM tYtE y0!

[Ghettokracker71]

Oh ****! How'd you manage to find that baby?

IIRC you should run the tap in your cold pipe,thats the actual boost about to enter your engine.

[nocwage]

15 Year law in Canada.If it's 15+ years it just has to safety and pass emissions.

http://www.japaneseimports.ca

[Ghettokracker71]

Gotcha. Must have been expensive in that case...anyway,I think you should tap your cold pipe. Don't do it until you get some more responces,but I'm pretty sure thats right.

[Trppen37]

i thought you tap in between the internal wastegat?

[iliketocrash]

i usually tap it somewhere on the intake mani. some people tap the line to their FPR. There's a big line that goes from the outer side of the intake manifold near the strut tower that i believe is supposed to go to the evaporitave emission can but i threw that out so i have my boost gauge running from that.

[rico05]

I tapped into the line from the back of the intake plenum to the FPR.

[mazdaman]

I tapped into the line from the back of the intake plenum to the FPR.

I searched on hooking up a boost gauge on a CA and this Jurassic era thread is what I got...

So the gauge vac is hooked up to the vac from the FPR? I haven't looked to see where the gauge is currently tapped in to on this engine as I don't own the car (as of yet) but should soon. I want to be prepared for when I get it At any rate, the boost gauge is sloooowwwww to respond under boost so I want to make sure it goes to an appropriate vac source.

Anyone with the know-how can answer this... Please!

[rico05]

Dude, I totally responded to your PM already, lol.

[mazdaman]

Dude, I totally responded to your PM already, lol.

Silly me!

But in my defense, this was here BEFORE the PM!!!

[capowered240]

vaccuum port on the intake mani.

[CaEric]

noc its slys13 ...i taped my from the side of the intake manifold

[mazdaman]

Any pics of said tapped source(s)?

[Masterdebater]

i tapped into my wastegate vac line just t'd it off.i know its not supposed to be that way but ehh... maybe thats why im only getting a reading of 5 psi boost....

[rico05]

Jebus Christmas....I'll get a pic for ya when I get home here in a bit. I have to do EVERYTHING for you don't I?

[mazdaman]

Jebus Christmas....I'll get a pic for ya when I get home here in a bit. I have to do EVERYTHING for you don't I?

Can you wash my dishes for me too, Rico?

J/K!! Thanks for the assistance in this....

[ch187]

wow. im glad i dont ask questions like this on this board. the correct place to tap into is right behind your throttle body pulley. you dont need pics for that one, and if you cant find it you really deserve to be driving my 1990 hatch i should be driving that silvia.

reason you tap there is because you want the pressure reading that is in your manifold because that is how much pressure that will be forced into the combustion chamber as soon as your intake valves open. its the most accurate and the closest port to those valves.

the reason you dont tap into the wastegate vacuum is because thats the pressure inside the compressor housing of the turbo. and you dont tap into the hot pipe for the same reason. you dont tap into anything before the intercooler because that gauge will not compensate for the pressure drop from the inlet of the intercooler to the outlet which there is esp. with FMIC. and you sure as hell dont tap into the cold pipe or anything before the TB because of this. think of the numbers on a boost gauge, you have vacuum(negative pressure) 0 which is when the amount of air being forced into the combustion chamber is equal to the amount of air being sucked in. and of course boost (positive pressure) when the turbo is actually pressurizing the combustion chamber and the magic happens. the reason most companies call them TURBO gauges because it reads both vacuum which every engine in the world has AND boost.

now say you are at idle. your engine will be under vacuum because the turbo is not spooled up. if you are tapped into anything before the throttle body your gauge will not read vacuum and finally the reason you dont tap into the back of the plenum where the FPR and the butterfly controls are tapped into is simply because its not safe. for each tap the pressure gets less and less accurate esp. when that tap in the manifold is really small.

note: i figured all this out the hard way. i may young but its all the personal experience that matters. i have tapped into i think EVERY way mentioned and have not had success. it takes a lot of trial and error to get things right the first time you do it. i never had someone tell me how to do something, why thats the right way and why the other ways are not correct.

[Masterdebater]

i have my wastegate fed from the nippple behind the TB. i have that line split off for the boost gauge so i still get vacuum. its just showing what the wastegate is showing, somewhat. and i have the BOV t'd from the FPR. i doubt its the best way but its for now.

[ch187]

wow, thats pretty bad. yeah itll work for now..

[Masterdebater]

lolso what vacumm sources are their..one on the back of the mani and one by the TB pulley and what else?

[mazdaman]

I really appreciate the help and all, but I really feel snide comments aren't necessary. Your post wasn't really bad for the most part, but I am about 99.99999% sure you have asked someone for something before in your lifetime. Hell, at least I utilized the search feature instead of starting a new thread . I am still fairly new to Nissan engines and when someone references a "vacuum line behind the plenum" or as you mentioned "after the throttlebody" There is still much room for error as I have never seen so many vac lines on an EFI vehicle before these engines..

I have also seen applications where just about all the vac was ran from the brake booster vac line as well...

So at any rate, thanks again for the input, but go easy, ok?

[mazdaman]

I took a look at the engine today and I saw the place you were speaking of... Yeah, I can say it would take a complete 'tard to miss that one!

That is where the boost gauge is currently tapped... HOWEVER, it's tapped from the end of the 9,000,000,000 mile long stock tube that's there as well...

So, my other question is this... Providing I just T off right at the nipple, that should help remedy the sluggish gauge?

[ch187]

yeah man the amount of vacuum ports on the ca isnt that bad. haha. but i teed mine right at the nipple. ran the bov hose under the cold pipe and under the cas ( theres a metal clip which you can bend and i tucked it in there to keep it away from the fan) and right into the back of the bov.

i didnt mean for anyone to get offended by my post. and i have asked people for help and it often wasnt the right to do things. all i want to do is help because no one really helped me with my swap. i made thread after thread and no one had **** to say.