Cut-outs !

[Captainsilverback]

anyone ever did cut-outs on a FD? is it possible?

[a7xh7]

are u talking about using a hole saw to cut the rear bumper and venting the front to get air flowing to different things

[85rx-7gsl-se]

I assumed he was referring to exhaust cutouts?

[a7xh7]

or santa shapes :)

[SLOASFK]

given the tempermental nature of the FD, I don't think I'd want to risk instantly losing all back pressure in the exhaust at WOT.

[ObliqueFD]

Isn't back pressure a bad thing on turbocharged cars?

[RXtacy]

Isn't back pressure a bad thing on turbocharged cars?

In general yes, but if you have your boost at a set value with a given back pressure and all of a sudden that back pressure goes away... Well you overboost like crazy and your motor will probably not be in great shape afterwards.

[busted7]

To add the the above comment: You would need to tune for open cut out and also closed cut out. I guess it could be done but the only reason i can imagin would be if your in a state were you have to maintain stock exhaust but want performance at the switch. If you state your goals it would help!

[Signal 2]

....the only reason i can imagin would be if your in a state were you have to maintain stock exhaust but want performance at the switch....
^Agreed. Regardless, anyone comtemplating should understand that many States...probably most, have statutes outlawing exhaust cut-outs. In my State they aren't widely enforced anymore, especially with the Hot-rod's growth in popularity the last few years. But the statute is still there. And if a State has visual inspection, a cut-out is hard to hide.

[ledgebmx]

Here in NC one of the cars I used to work on had a 3" cutout on a 20b FD. The owner did it for performance, cost and noise reasons. It's expensive to purchase/fab a 4-5" exhaust that is quiet enough to pass noise laws but the 3" exhaust restricted the potential of the engine. He gained around 80rwhp with the cutout open at WOT. I think he dyno'd ~650rwhp @ 17psi all said and done.

I think the biggest factors are exhaust restriction and tuning issues. I would imagine you would tune with the cutout open and just deal with not racing with it closed very often. It's possible to tune for both if you're not running an exhaust that's too small (IE 3" on a 20B). You'd have to keep an eye on the tune but that's a given with these cars! :driving:

[cewrx7r1]

Some production sports cars now come with some form of exhaust bypass that open at full throttle. Ferrari and Corvette are two that use them.

[RXTASY]

Have a 3" Quicktime cutout on my exhaust.
One of the best mods I have ever done.
Turbo spools quicker and boosts a little higher, plus it sounds wicked as hell!