[Guest]

With a turbo car, whats the best way to impove torque, or make sure you don;t loose any torque when changing the exhaust.
I've had part of the front flexy baffle thing on the turbo downpipe break up (makes a hell of a racket) and it'll need replacing. Seeing as it is cheaper to have one made from SS than buy a new standard one I'm tempted to get a free-flow system built up and a full system to go with it (seeing as I'm still on the original standard system!)

The HKS ones are more expensive than a hand built one (unless anyone can do e a good deal !) but what sort of system is best.

What sort of size pipe should I be looking for, is some restriction advisable to help the engine work (back presure) or should I fit something akin to a howitzer ?
Or should I just get a Evo 3 group N system fitted ? (This is an Evo 1)

Any of the 4G63 tuning bods out there know ? (Wrecklford ?)

Thanks in advance....

TonyC

 

[Guest]

For any exhaust backpressure is bad because it increases pumping losses, i.e energy that is used as the piston pushes out the exhaust gases. The back pressure is proportional to the square of the flow and as flow is (almost) linear with engine speed you will get 4 times as much back pressure at 6000rpm than at 3000rpm. This is why a free flowing exhaust gives a greater power increase at high rpm. However you will still get a worthwhile increase at maximum torque.

In the past people have said that a certain engine needs some backpressure. this is ######. What they mean is that with a low back pressure exhaust the mixture/ignition timing needs to be changed for optimum performance.

The ECU in an Evo is smart enough to cope with an exhaust change as it measure mass flow of air into engine. what can happen is that the mass flow exeeds the fuel cut limit and you get fuel cuts.

Hence if you could fit a 6 straight through pipe from turbo outlet this would give better economy, torque and power than the standard system, although you would not be very popular with your neighbours .

 

[Guest]

2.5 diameter stainless steel custom is what I have on my VR4 - really gets the turbo to spin more easily.

Go for 3 if you want monster power.

If you want improved mid-range torque then a good boost controller to up the boost mid-range is the way to go. I'm a cheap-skate so I just use a bleed valve set to 1.0 bar.

The HKS is very overpriced for what it is.

 

[Guest]

Like I think I may have mentioned before I recently got a full 2½ S/S system from the turbo back for £340 (no cat, no darn flexi). Fit etc. is excellent and the difference in spoolup is quite remarkable, I'm still constantly surprised by the extra grunt available. I'd recommend the bloke who did it although he is rather busy - you'd need to make a wee trip up north for it though, he's based about 15-20 miles outside Edinburgh.

Drop me a line if you want more information [email protected]

 

[Guest]

The mongoose has a flexi piece built into the neck of the down pipe .