Dumb Question Thread!

[kamineko]

yeah, black to back. a common error is to plug the cam sensor plug onto the front injector. same plug, similar colour

[ultima1691]

???why do subarus have rear cvs? ???

[rex-leggy]

because they are 4wd

[ultima1691]

but why cvs? seems strange to have cvs on wheels that dont turn..

[Kiwi_Fozze]

suspension travel

[Koom]

 kwi_fozze said:

suspension travel

Independent Suspension travel to be even clearer.

[Kiwi_Fozze]

[kamineko]

 ultima1691 said:

but why cvs? seems strange to have cvs on wheels that dont turn..

also remember that the rear wheels do have the ability to 'steer' a small fixed amount, most cars are set up to run some rear 'toe' to help stability at speed, as well as camber. this and the suspension travel of the wheel relative to the fixed diff requires the Constant Velocity joint.

you could probably use a different joint but CV's fairly reliable, and already manufactured for the front, why make something different for the rear when it works.

what joint did you expect to find? there is a universal joint on the driveshaft, but its expected articulation is quite limited.

[Divine]

What does this thing do?

Drivers side of the passenger bay, I'm holding the hose that was tucked away, other side is that small pipe.

[Guest]

Looks like a vacuum line for the factory boost controller

[Divine]

Ok thanks

[reaperblitz]

Do you unplug all vacuum lines from stock boost controller if you have an aftermarket mbc?

[Kiwi_Fozze]

no. the line between the churrbro and the wastegate should have the mbc in it. the tee piece that was there, plug it up. done. dusted.

[QRAF]

silly question but as i have two left hand fuel rails should i have my injectors up the other way?

[funkytown]

no thats all correct QRAF. You need to make sure the plumbing is correct

[Kiwi_Fozze]

reaperblitz, yep thats what i did. only line you need to touch is the line between the compresser housing and the wastegate.

[Jimbob]

anyone got manifold diagrams for a v3/4 setup? ie vac lines fuel lines etc

[subi4snow]

 Jimbob said:

anyone got manifold diagrams for a v3/4 setup? ie vac lines fuel lines etc

+1, looking for the same here

[QRAF]

 subi4snow']

[quote name='Jimbob said:

anyone got manifold diagrams for a v3/4 setup? ie vac lines fuel lines etc

/quote]

+1, looking for the same here

i'm looking for it for the ver5/6 setup

[Divine]

How fast does air pass through the intercooler? In regards to say, the piping on a front mount, at 700rpm and 7500rpm?

[Joker]

http://autospeed.com/cms/title_TopMount-Trial-Part-Two/A_1619/article.html

and

http://autospeed.com/cms/title_The-Worlds-Biggest-Intercooler-Comparison-Part-Two/A_1946/article.html

may not have the answer to that

[wrx_lou]

Too many variables in that question. Would depend on pipe and inlet sizes, intercooler size and boost levels. Obviously there would be a huge difference between 700 & 7000 rpm.

[Koom]

 Divine said:

How fast does air pass through the intercooler? In regards to say, the piping on a front mount, at 700rpm and 7500rpm?

If you can estimate the cfm at various rpm points (squirrelpf have an excellent online turbo compressor map estimator that gives cfm across a range of points, also so does Matchbot, the BorgWarner turbo estimator thingy), then you can easily estimate the velocity given the diameter of the part of interest.

i.e. given 450cfm (estimated flowrate somewhere around 300hp), then the velocity of the air through a 3" intercooler pipe would be V = Q/A

[Where V = the velocity in ft/s, Q = flowrate in cfm, A = area in square inches]

Can then convert to metric (onlineconversion.com)

So 450cfm through a 3" pipe gives ~153ft/s which =168kph.

You want to keep most airflow situations to less than 0.5 the speed of sound as there is all sorts of horrible drag restrictions once you get up to too high of a speed.

p.s. All of this is just quick estimates off google, I haven't checked any of those numbers.

p.p.s. to estimate velocity through the core itself, will involve a whole bunch more estimations unless you want to chase the thermodynamics super accurately.

[Divine]

Awesome thanks, will have a bit of a read

[aim]

The air will stop behaving adiabatically at higher velocities, erosion and heat start to become massive issues. Your intercooler won't be able to keep up... wouldn't start worrying about that until about 100m/s though... ~360kph.