exhaust, 2 or 2.5 inch

[Ralphh85]

im building a full system for my car, currently 3.5 but may well end up 3.9 and would like to see at least 230bhp.

im using 1.5inch fr primarys and secondarys, going in to 2inch down pipes, then im wondering if i should bring these in to a single 2 inch or to go up to a single 2.5 inch.

if its not going to make much difference to power then i will go for 2 inch as it will probably keep noise down.

the range rover only had 2 inch ish exhaust?


Ralph

[RoverP6B]

Hello Ralph,

As you are using 2" downpipes, the pipe that they merge into should be slightly larger in diameter, so from all the research that I had done when I was sorting out my own, 2.25" would be the way to go.

You can always go to 2.5" further along, say 2.25" muffler inlet and 2.5" muffler outlet.

Ron.

[Ralphh85]

i have 4 in to 2 manifolds, then the 2 will collect in to 2inch pipes, then where i merge the 2 x 2inch pipes is the bit i have not decided.

im buying the pipe down the road (cause its free as work pay for it) and they only do half inch increments so its either 2 or 2.5 inch?


Ralph

[ian.stewart]

I run a single 2.5 pipe with just short of 300hp, and a single flowmaster rear box, Noise, not a problem!!!!.

[Ralphh85]

you rear silencer, is it a packed one? and how noisy is the car?

guess 2.5 inch is probly the way to go then.


Ralph

[kiwicar]

Ron is spot on, if you have 2" down pipes then you should use a 2.5" system, that is if you are going to run a single system (like Ian). If you are going to run an X pipe set up and twin pipe system , ie merge it and split immediatly then the 2 x2 inch pipes are ideal. To be honest at 58 bhp per litre then the exhaust isn't close to being the limmiting factor, provided it provides enough flow (2x2" or 1x2.5") overall it is fine.
Mike

[Ralphh85]

im not a show off so 1 exhaust will be fine for me

2.5 inch it is then!


cheers people!