I have flowed original headers at the moment, but paranoia is taking over again and i think I might have a leaking centre joining pipe.

I know some aftermarket tubular header are much larger in volume which doesn't help torque lower in rev range.

Does anyone have a experiance of how this single component helps / hinders power / torque?

I have a 97UK car with hybrid TD04 + supporting mods. It's 99% road use.

Thanks

 

Aftermarket headers move spool up the rev range and make more bhp, ported move it down and improve torque.

 

Depending on length/diameter of course, but yes, most AM tubular headers do as 500 says, ported headers with only a small diameter and volume increase have little effect on spool (maybe small positive effect) but reduce some of the higher end deficit to the tubulars.

Simon

 

Thanks guys.

Pretty much as I thought, although I remember seeing some AM headers advertised with low volume as a feature to help torque.

Just wondering if anyone had a before / after comparison.

To be honest I haven't the funds or time to swap at the moment, so it's a bit accademic until I really need to do something.

Thanks though

 

on my sti 8
on ported headers got 330 bhp and 351 bhp on tubular headers with 40mm uppipe

 

Thanks Ian

That's what I was looking for - did you notice drop in torque low down ie town driving ?

 

Why do you think your centre pipe is leaking clint ? I ask as I have the same suspicions - when they went on there was more 'flex' than I thought right....


Steve

 

I've recently swapped my ported OEM headers for some tubular headers from Zen. Significant increase in torque from 4K upwards and bucketloads more top end power, with virtually no loss of spool or low down torque. Very impressed and happy

(03STI running MD321H BTW)

 

My suspicion is down to noise - I can't pin point it - it's not that obvious but occasionally I think there's a leak from somewhere at the front and the link pipe is pretty flimzy.

I was porting some OEM headers (my original ones actually) and the link pipe just broke, it was pretty corroded so it didn't surprize me.

It might be because i don't stand outside the car with the engine running much and I have been recently, as I said paranoia kicking in again. I'd thought I'd finished so it's probably the 'mod bug' kicking in subconsiously

Interesting to hear your result Lunar trick - cheers.