Up The Boost - With Controller Or With Exhaust

[nuffsaid]

Hi all

I have a question.

Say if you up the boost of your car by using a boost controller and boost reads 10psi,

is it the same as your boost getting upped by a full exhaust to 10psi?

ie. is the effect of a full exhaust increasing boost the same as actually boosting it up via some controller?

I ask this because I have read on these forums that a boost increase by an exhaust isnt actually different to a controlled boost increase. Some have mentioned that an exhaust boost increase is not an actual increase in turbo pressure, something about the boost in the engine being different to boost in the actual turbo itself?

*confused* maybe Ive read the posts wrong.

Thanks

[GreddyGo]

You could do it with a controller, but boost may drop at high rev's due to the restriction.

If it's more power that your after I would go for a full exhaust system!

Cheers

Josh

[nuffsaid]

Hmm I already have one and boost has gone from 8 to 10psi because of it.

Just wondering whether getting an EBC will give me more power if I set boost to 10psi, ie. will I be able to run "more" boost in the actual car if I dial it in at 10psi.

Or will I have any other significant gain.

[ryan_o_grady]

I think you forgetting the fact that you guage should be reading maifold pressure.

10psi is just that.

It is a figure there is no diff between 10psi achieved through any boost controller or by an exhaust.

[nuffsaid]

Its a stock R34 GTT boost gauge, where is that reading from?

So 10psi manifold pressure = 10psi turbo pressure?

[CEF11E]

except that pressure is measured as a resistance to airflow.

10psi with a full 3" exhaust will flow more air as the resistance is less.

[satanic]

Don't forget that a boost controller does just that; controls the boost... if you set it at 10psi then it will constantly stay at 10psi.

However, if you think about it, controlling the boost with the exhaust mod will not be as accurate, there will be fluctuations.

[nuffsaid]

So do i gain anything out of getting an EBC over using the stock boost control system seeing as I am already on 10psi?

Dammit was hoping to get more out of the car by upping the boost, darn exhaust has already done that.

[Munna1]

Thats interesting how boost seems to increase on peoples cars after an exhaust is installed it made to difference on my car at all boost was still 7psi before and after.

[Munkyb0y]

mine reaches around 9psi, stock boost solenoid, exhaust and pod.

r33

have u got turbo back? or cat back. that may be the difference. also, highflow cats etc.

Edited September 29, 2006 by Munkyb0y

[Lachlan33]

Hmm interesting thread, im waiting for tax return then its full turbo back with hi flow cat.

I want my extra boost!

[Race__24]

You'll gain power down low with an ebc due to the boost coming on earlier.

[mad082]

if you are only going to run 10psi i wouldn't bother with a EBC. that is a lot of money to spend to gain a very small amount. i'd get one of the $22 boost controllers. that will bring the boost on earlier.

[TTT]

Make sure you understand boost first.

Your engine burns fuel and air and send it out the exhaust manifold which flows past the turbine which it spins along the way.

Which in turn spins the compressor wheel which sucks in the air. And the whole process flows through.

Now, you get a larger exhaust, the gases coming from your engine has more room and can flow more, and there is less back pressure at the exhaust wheel of your turbo, which means it spins more, which in turn spins the compressor wheel, which sucks in more air to the engine.

That is the increase in boost pressure.

No factory set up measures the boost pressure at the turbo.

It is always measured AFTER the throttle body.

So with the intercooler in the way, your turbo might actually be spinning up 12psi of pressure but the intercooler is a restriction and by the time it gets to the engine, it is only 10psi worth.

All the factory restrictions like the back pressure caused by stock dump pipe etc, and the restriction in the intercooler, or the stock air filter maybe..

Once these are freed up, you will see a higher pressure amount.

Is there a difference between 10psi via a boost controller or via the free flowing exhaust?

NO.

Is there a power difference? you bet there is.

Do a search for “ BOOST+SYDNEYKID” from any date.

He had a really good explanation of boost and so on.

Unless he sees this and posts it here himself.

[wolverine]

hang on GTST, higher flow due to lower restriction should lead to a decrease in pressure. (depending on where you are measuring it). then you load up some pics of Bernoulli's Effect and your head gets more messed with.

Edited September 29, 2006 by wolverine

[mad082]

theoretically the boost pressure shouldn't rise with an exhaust size increase. why? if you start flowing more air out of the exhaust, the turbo will spin faster, and compress more air into the intake. the wastegate should see this and open sooner, but still at the same pressure, slowing the turbo back down. the only way that the pressure could increase is if the wastegate can't flow enough air due to a higher restriction.

[WazR32GTSt]

you're all forgetting something guys... what about "wastegate creep"?

yes a boost controller and exhaust will both work to increase MAX boost level,

BUT

with a full exhaust, the wastegate still creeps open at low-mid rpm giving you a gradual increase in boost

a boost controller stops any manifold pressure getting to the wastegate actuator until max pressure, so it will build boost faster than simply having a free-flowing exhaust

of course having a boost controller with no aftermarket exhaust is also kind of stupid as throwing all that exhaust gas into a restrictive pipe isn't going to yeild as much power so why bother upping the boost at all?

Warren.