does the size of a exhaust manifold matter in turbo spooling

[pbwu1f]

does the size of an exhaust manifold matter in turbo spool up. i have a auto awd, with a Megan tube manifold. i noticed that the turbo does take quite awhile to spool up. im getting spool up right around 2800rpm, but i would like to be quicker. i do have a 18g, and i think that just the way it is. thanks

 

[My1GLaser]

Yes. I was porting my 2g mani last year and really hogged it out and it killed my spool. So I swapped it out with a mildly ported one and it spooled up a few hundred rpm quicker.

I recently switched to a FP race manifold and didn't notice any significant change one way or the other though.

What makes the biggest difference is timing IMO. I have ECMLink and have added about 10* of timing under the boost threshold, and the boost is much more linear. Normally a smaller turbo comes on all at once with a big torque hit, but mine doesn't quite act the same anymore. I am in boost as soon as I touch the gas in any gear. I really have to barely accelerate or I start seeing boost immediately. My full boost is still about the same...28-30 psi at about 4k.

Also, I retarded my exh cam 1* with adj cam gears and that brings boost on sooner.

 

[95redturboawd]

I would think that the more you ported it the quicker the turbo would spool, is that not the case?

 

[954TalonTsi]

My friend had the same problem when he heavely ported his 2g manifold. So no the more port in it dosent mean it'll spool quiker. My friend also found that he spooled quicker with 2.5" IC piping then with 3". Just another example that more isnt always better.

 

[LiquidX]

My friend had the same problem when he heavely ported his 2g manifold. So no the more port in it dosent mean it'll spool quiker. My friend also found that he spooled quicker with 2.5" IC piping then with 3". Just another example that more isnt always better.

That's because the turbo isn't pushing enough air to make it to the engine quick enough since the piping is bigger and needs more air to fill the piping.

 

[My1GLaser]

I would think that the more you ported it the quicker the turbo would spool, is that not the case?

The exhaust loses velocity going into the turbine housing and results in slower spool due to the bigger opening. I assume that it would be able to flow better at higher rpms where exhaust backpressure becomes an issue.

 

[1gDSM4g63]

It shouldn't be that noticeable especially when you're talking about a ported manifold vs. unported, although it provides more airflow and prevents less choking.

You have to ask yourself the question if you want to give up spool time for more power.

 

[d_hidayat2000]

Definitely,
- Exhaust Diameter
- Exhaust Length (from engine - Turbo)
- Bend, No sharp bend
- Equal length from cyl 1-4

those will affect how turbo spoolin
large diameter exhaust is good at high flow, but usually lack of mid range torque/spool up
so it depends on engine/turbo setup

 

[blowinsmoke95]

i didnt know that i thought bigger was better

 

[1990AWD]

Its just like how Mitsu went to a head and manifolds with smaller ports and turbo for 2g cars. It made much quicker spool up because the air was travelling faster but lacked the mass flow of the 1g.