Exhaust Manifold.

[Mr Whippy]

Right now no one that I know of has done head work AND has any results to show it was worth doing at all... Ie, car is at 220bhp, they can't seem to tune beyond it, turbine intake pressure isn't going up despite more fuelling, maybe it's bad flowing ports? Open up ports and suddenly they see 235bhp. Great. Tune more, 250bhp. Wow, glad I ported the head!

Until you see that kinda thing happening, or work through methodically like that, then you may as well just burn a wad of £20 notes.

But until someone has tried it, how are you going to know.....someones gotta man up first.... I know you can go so far with calculations...but meh...maths / calculations say that 90% of the things I do are wrong...but if i crank things back to where there "meant to be" it looses power...its just swings and roundabouts

Indeed, I'm all for supporting people trying it... 100%

But don't just do it alongside some other mods while your at it. Do it scientifically. Do a before/after check on pressure/temps and leave everything else the same.

Find out the actual difference it makes and then you can quantify the benefits of the mod for your needs.

But to be honest there is a list of other stuff that is important to get done first for even getting to 200bhp, so I'd be wanting to get a solid performing 200bhp car first before looking at doing anything with the manifold.

If you just do a mod that no one else does but can't attribute any specific benefits to it then how do you know it was a mod worth doing? Magic? Guessing?



Porting MIGHT be a hindrance to performance, that is the problem. Exhaust gas velocity down the ports will decrease and that might impact all manner of turbo performance variables for your needs... ie, under 200bhp of exhaust flow the turbo might be less responsive, and generally you might find yourself optimising for over 3000rpm+ power.
Considering diesels have a limited power band any way, over-sizing ports might be a *bad* thing depending on the other things you want to do.

I'm not 100% on that, but until you are I wouldn't waste time modding something when you have a PROVEN list of mods you should make right now that you can be getting on with and perfecting before messing with unknowns


By all means DO do the mod, but check what changes before/after... only then will you know if it's a mod worth keeping on the car!

Even if the only test you do is a dyno run... it's at least something.

The amount of people I have seen make mods (good on them for trying) but failing to test before/after is the number one reason why a lot of cars fail to make the power the owners expect on a dyno!


You don't have to be clever or do maths/sums/calculations, I rarely do it beyond fag packet maths as there are so many variables at play.
All I'm saying is do some testing to isolate that mod as the single variable and then see what it's like before/after

Dave