J_sca001

I have a classic WRX running at around 300BHP. I was advised the next mod to go for would be new "headers" What are the benefit of them, the cost and would i need a re-map? Also, what does it mean to have "Ported" or "Gas flowed" ? ? ? Help a newbie!!!

orbix

What little I know on the subject i'm happy to share.

The choices are you can buy a new set of headers or you can have your OE's ported.

I don't know what "gas flowed" means I can only take a guess at a new set of headers wound be bent and tested with the gas flow in mind rather then just bent around the engine bay components.

You can have your original headers ported this is where you grind
excess material away to improve gas flow/velocity.

If your considering headers you may as well change your uppipe as well if you haven't done it.

Changing both you should find a improvement in spool, power and smoothness.

It's also a good idea to heat wrap them.

I don't know about a remap, I think you'll be looking best part of £400 for someone to do this work and heat wrap them.

bluerigster

iTrader: (9)

When porting cylinder heads and mainfolds etc this means the entry & exit points of either are polished to increase the diameter and to remove any rough edges which could restrict the flow of air or exhaust gases etc. To gas flow either of the above this refers to equally matching each manifold etc. This is done by flowing gas and mearsuring the output and comparing to the other, if any difference in gas flow is noticed. The manifold etc with the less flow would be ported (polished) further until the gas flows matched up. As for changing your manifold this would alter the spool up of your turbo and allow for more response when combined with a aftermarket down pipe. I personally would change your down pipe to one with a sport cat (pass MOT)and wide neck. Decat the centre section of your exhaust system an back box if not done so already to allow for better breathing. Fit a pipecross filter element to the original air box, change your injectors to 550cc items and fit a walbru 255l/hr fuel pump. Source a TD05 18g turbo and have a ECU remap. All these mods would return the best BHP increase for your money. I would not change your headers with the amount of mods carried out, no real gains would be acheived

J_sca001

MarkFitz

Porting the exhaust headers (US speak for exhaust manifold) is a great value for money mod and can be done for the price of a set of gaskets, if you've got some very basic tools and are up for a bit of DIY.

Otherwise you can pay someone to do it but could be costly in terms of labour time since the process involves removing the exhaust manifold and boring out the internal diameter of the pipework to match the size of the exhaust ports on the cyl. heads.

As a result, the exhaust system will be less restrictive and you'll see benefits in performance, driveability, fuel-economy, turbo spool-up, and best of all you'll reduce the exhaust gas temps!...

Gas flowing is a more serious proposition and well out of my league to comment on, ( check out ...CNC Heads ).

You could ditch your standard headers and buy any number of aftermarket versions (tubular, equal-length, ceramic-coated, bla, bla bla) but theres a good case to be had for just porting the one you've already got.

Proabably best to remap following any mod that'll increase the airflow through your engine...much cheaper than the cost of a rebuild, IMHO.