4:2:1 v. 4:1 long header exhaust system

[Englishmaninwales]

Is there any significant gain in having a 4:2:1 over 4:1 long header exhaust when fitted to 1800 k with SS (correctly timed) cams, standard unported head and supersport plenum (old type)? Cost 2nd hand seem to be £300-500, and I wondered if this is cost effective.

 

malcolm

[Ash.Bailey]

🙆🏻deleted cos I was talking about a longer primary 4-2-1 vs caterham 4-2-1.

 

 

If ^It aint ^yellow, wonky ^and wobbly................ 😬

 

 

Edited by - wonkycustard on 28 Dec 2006 12:03:11

[Peter T]

Certainly a 4-2-1 exhaust promotes the torque to be lowered in the rev range as oppsoed to a 4-1.But whether you will gain much from just swapping them without a mapable ECU i cannot tell you. A before and after session on a Dynoe will give you the result.

 

R500 Mango Madness

[Howard R]

Hi Malcolm

 

The 4:2:1 is supposed to give more low down torque.

 

It would be worth putting your car on a dyno 1st - to see if it lacking in torque + power - not that I think it is (apart from racing blue Izuzu pickups through Wales 😳 )

 

Best wishes for New Year

H

 

 

 

 

[david nelson]

Malcolm

 

I did this mid season and there is a diffrence. It was the only thing I change but the car felt more alive. I am not sure that it made me any quicker.

 

 

David

[Rob Walker]

Come on Malcolm you know you want it, it is futile to resist. 😬

[CageyH]

Malcolm,

 

Buy this to stop me!

 

Only dead fish go with the flow....

[Bozz]

I've changed from a short primaried 4-1 with cat to CC 4-2-1 w/o cat and IMHO the increase in torque, especially in the midrange, is significant. Hope to do another dyno power run again sometime to confirm what I can feel through my 🙆🏻 😬

 

Not sure how noticeable or cost effective it would be to change from the long primaried 4-1 though.

 

Bozz

 

McLaren Orange and Black 1.6SS 6 Speed here

[Jason Plato]

I changed from 4-1 > 4-2-1 Caterham systems and there was an increase in midrange torque with no losses at peak, tested at Emerald. The 4-2-1 also filled in a hole at around 5500 of about 8ft/lb. You realy need to optimise the cam timing too, add a larger throtlle body and connect up a cold air feed to the plenhum .

 

 

 

here is C7 TOP

Taffia Area Rep

[Englishmaninwales]

Rob W 😬

 

Dave J:

You realy need to optimise the cam timing too, add a larger throttle body and connect up a cold air feed to the plenum

The cam timing is as set up by Dave Andrews. Are there better settings for the 4:2:1? I'm restricted (class 2 regs)to the standard TB as fitted to the SS aluminium plenum. Cold air is an easy mod for the forward facing TB

 

 

 

[Jason Plato]

I think the cam settings are the same unless you were to experiment on the dyno with the exhaust .

 

I think its more what the mems and IVAC can cope with as overlap and reverse pulse etc than the introduction of the exhaust.

 

are you using a forward facing 1400 plenhum then ?. That has a huge throttle body no worries there then

 

 

[old captain slow]

Malcolm,

 

It looks cool so what other incentive do you need.

 

Oh! If asked why you did it, the stock answer is it's a safety improvement.

 

C7 CDW