Will Changing My Fmic Piping Increase Power Or Work

[4drftn]

high guys, i have 2 1/2inch intercooler piping on my rb25 and was wondering would it be alot better to up it to 3inch? As i have been told bigger piping will also reduce turbo lag...

Also my piping runs different to alot of peoples intercooler piping, as mine runs under my FMIC and up into piping to turbo...

i have attached a quick (um very quick) diagram of how it runs... will this be worse, cause im thinking the angles in the piping are bigger angles and may affect airflow...

just your thoughts on this situation will be a great help... cheers

[SKYHY]

high guys, i have 2 1/2inch intercooler piping on my rb25 and was wondering would it be alot better to up it to 3inch? As i have been told bigger piping will also reduce turbo lag...

Also my piping runs different to alot of peoples intercooler piping, as mine runs under my FMIC and up into piping to turbo...

i have attached a quick (um very quick) diagram of how it runs... will this be worse, cause im thinking the angles in the piping are bigger angles and may affect airflow...

just your thoughts on this situation will be a great help... cheers

you are going to lose psi if you go too big you will need to up the psi on the turbo, and dont have angles int he piping as it will be restrictive.

[MBS206]

A larger pipe means the turbo has to supply more air to get up to pressure.

So going to a larger piper actually increases turbo lag.

[Cubes]

Thats how I have my fmic setup.

All though not the best technically due to the great big dirty 180degree bend but it works. I prefer this setup as it keeps the engine bay clean.

[InterCooL]

high guys, i have 2 1/2inch intercooler piping on my rb25 and was wondering would it be alot better to up it to 3inch?

my thoughts = that's a lot of money that could be spent elsewhere. most likely will increase lag by a small amount with no payoff

buy a set of injectors or a boost controller or something that you will actually get some performance out of

[BHDave]

Changing the piping route will save about 60cm of piping, I've had a set up similar to yours and the more common across the top of the radiator way and to be honest there's not a lot of difference between them. In your case, the tightness of the 180 bend may be an issue but how much effect it has is anyones guess

Stick with 2.5 unless you have a front facing plenum and a 3 inch throttle body, then change it to 3 inch on the cool side so the diameter isn't decreasing then increasing for no good reason.

[mad082]

unless you have a bigger throttle body all you would be doing is increasing lag. boost pressure will remain unchanged. depending on where you have the wastegate and gauge getting its signal from the pressure your gauge is reading may change, but the pressure that the turbo is creating will not.

[W0rp3D]

This is also assuming you arnt making 300+rwkw, if you are then 3" pipe will probably be needed.

Maybe try to find a fmic that has the in and out on the same side, if you do find one let me know as i am trying to find one to get all the piping out of my engine bay.

[xRHETTx]

A 180 degree mandrel bend will only add at most 1.5 times its length in restriction.

So if the pipe in the bend is 40cm long, it adds the same restriction as a 60cm piece of pipe. So if you are reducing the piping length by 20cms but having the bend you are ahead.

[Cubes]

So which would be better from a flow point of view?

Having the hot air do the 180degree bend in to the fmic or having the cool air leave the fmic and push through the 180degree bend?

Are we better having the hot air travelling the longer distance or the shorter distance?

I 'probably' think its best to have the hot air do the longer run. But I really don't have much of an idea with regards to flow dynamics.

[mad082]

you are best of having the hot air travelling the longer distance. this gives the cold air the least amount of time to warm back up.

[Cubes]

Mad082,

But the cold air shouldn't warm back up because its out of the engine bay.

My thoughts of having the cold air run the shortest distance was to reduce so called lag as the cool air occupies less area so would take longer to fill the ic piping.

BUT in practice would there be a noticable difference. Probably not.

[mad082]

that too. yes cool air does occupy less space. which makes me wonder why all the aftermarket piping kits for ca18 and sr20 have 2" or 2.5" from the turbo to the cooler and then goes to bigger piping after the cooler. just doesn't make sense to me.

[Pal]

A 180 degree mandrel bend will only add at most 1.5 times its length in restriction.

So if the pipe in the bend is 40cm long, it adds the same restriction as a 60cm piece of pipe. So if you are reducing the piping length by 20cms but having the bend you are ahead.

its a choice i spose, i have mine this way too, i prefer a clean stock looking engine bay compared to 2 more rwhp due to more restrictions in my pipework

[xRHETTx]

OK my guess is that the cooler the air is, the slower it travels (as it occupies less volume).

As friction is a factor of the air speed squared, you are better off having the "hot side" of the cooler shorter with less bends than the "cool side".

But this is opposite to what you've shown above, so I'm probably wrong.

[djr81]

OK my guess is that the cooler the air is, the slower it travels (as it occupies less volume).

As friction is a factor of the air speed squared, you are better off having the "hot side" of the cooler shorter with less bends than the "cool side".

But this is opposite to what you've shown above, so I'm probably wrong.

You are correct. Pumping losses for airflow in piping systems are very temperature dependant. Therefore you are better off having the cool side on the longer run if you want to avoid frictional losses.

With regard to lag there are two different sorts:

1. Turbo lag, ie time it takes the turbo to build up tot he requisite boost.

2. Throttle lag, ie time it takes for all the air to go through the induction system, intercooler included.

As is self evident what helps turbo lag will hinder throttle lag. So you pays you money & you makes your choice.

Better off spending it elsewhere.

Edited July 10, 2007 by djr81

[DRD-00F]

plenum... much less piping, but then theres the flow and starvation problems that come along with it... especially if running low boost...

but still, HAWT

[W0rp3D]

http://cgi.ebay.com.au/Intercooler-Univers...1QQcmdZViewItem

Will a design like that be any less restrictive, planning on getting one made so i have maximum size for the space i have, that particular one is a bit small for me.