3" catback - Good idea or bad idea on a N/A Protege?

Thinking about the Corksport 2.4" or the 3.0" for my N/A 2.0 Protege. The reason I'm even CONSIDERING the 3.0" is that I want to go from N/A to turbo and don't want to have to buy the exhaust twice (i.e., first the 2.4" and then upgrade to the 3.0" when I go turbo).

I could hold off on the exhaust until I go turbo, but I am trying to upgrade everything but the turbo so that when I go turbo, I don't have to subsequently spend a lot of money.

Thoughts? Will I lose a lot of low-end if I use a 3.0" exhaust prior to going turbo?

I had a 3" cat back on my NA 2.0, I had the same idea.... I knew I was going turbo so I just bought the exhaust I wanted. I didnt feel any loss in power.

Rob

Thanks for the reply. Hoping some others will chime in with their experiences as well.

Btw, I took a look at your build thread . . . impressive to say the least. I don't think I would have the patience to do all of that, nor the energy. But kudos to you.

On my "list" (this mythical list in my head about where I want to take my 2002 Silver Protege ES in terms of mods) are many of the things you've already done. Namely, in terms of sequence of events: Stoptechs go on next week (had a new set of rear calipers power coated to match . . . they'll go on at the same time), as well as a Corksport front and rear set of strut tower bars (had the ends power coated red . . . as that's my accent color of choice), new front and rear wheel bearings/hubs, a new billet battery tray for my red top Optima battery, a red wire NRG grounding kit (trying to get rid of that annoying engine wine in my recently installed Avic Z-120BT) and some Momo pedals to match my Momo shifter and ebrake handle.

Next up is a HID project retrofit, then a new exhaust (probably 3" based on your feedback and hopefully others). And then it's probably time to move on to my transmission. My transmission is probably getting a little "long in the tooth" anyway (165k+ miles), so a new clutch, flywheel, a Quiafe LSD, and new half-shafts . . . may also go the 3rd-5th gear heavy duty route, but don't know. And then . . . the engine. Probably just buy a built one from SpeedCircuit as well as their new turbo kit and BAM! I'm "done" . . . The good news is that everything up to and including the transmission should be done by March/April. Motor + turbo will likely take until next year. I've toyed with the idea of a c/f hood (and I like the way yours looks) but this car will likely be (eventually) handed down to my niece, and I don't want to do ANYTHING to potentially compromise the structural integrity or safety of the vehicle. And like it or not, a c/f isn't likely crash tested or approved.

Anyway, your build is very nice and inspirational. Can't wait to see your dyno numbers. Personally I'm shooting for a more modest 325-350 whp, not your 400+.

You may lose a little pep from a stop but honestly with 100hp would it make a difference.

Another thing worth mentioning is instead of a Quaife look into Mfactory for nearly 1/2 the cost.

Just so you know your modest 325-350 with the list you made (sc block + turbo kit) plus fuel pump, injectors, engine management with fuel and ignition control, stiffer motor mounts, KNOCKLIGHT!!!... Minimum $12k

I had read some not so encouraging feedback on the MazdaSpeed LSD (even the welded on) at higher HP levels, which is why I want to go with the Quaife . . .

Yeah, it's gonna' be a pricey upgrade path, that's for certain. But I've had this car for 7+ years and am buying a new vehicle (CTS-V) so this will be my second car and I just want to have some fun with it. I probably will try and figure out a way to do the built motor + turbo at something less than "retail". Maybe have the motor rebuilt locally and see if I can piece together a turbo kit on my own . . . we'll see. I will be about $8k-$10k deep in mods/upgrades at the point that I will likely be considering the motor/turbo combination . . . so who knows, maybe I will have reached my limit by then, I don't know.

My welded msp lsd is still holding for now at 350-400whp but Mfactory is rated at 1000hp and has lifetime warranty like the quaife and is only a little more than a welded msp lsd.

Ok, so what's the difference between a Quaife and an Mfactory ("I like savings da monies . . . " so you have my attention)?

Do they function similarly? One thing I'd always read about a Quaife is that they're relatively easy to maintain/rebuild. Is the same true of the Mfactory? What's the best place to buy the Mfactory? And by best, I mean lowest price. ;-) I've seen it online for $669 + and additional $140 for an installation "kit". . .

I'd not 3in catback it... loss in velocity will be pretty extreme. Even 2.5in for NA is "serious business"... and need only be used if you are chasing big NA numbers....

But since you are turboing at some point... *shrug*.

Is that based upon experience (i.e., you've seen this on a Protege and it didn't work out well) or is it opinion? Not challenging you (because your reasoning IS sound, IMHO), but I am trying to understand whether or not what you're saying is "tried and tested" (on a Protege) versus theory.

dhodory said:

Is that based upon experience (i.e., you've seen this on a Protege and it didn't work out well) or is it opinion? Not challenging you (because your reasoning IS sound, IMHO), but I am trying to understand whether or not what you're saying is "tried and tested" (on a Protege) versus theory.

Click to expand...

Bit of both...
i know a 2.5in will seriously diminish the bottom end (noticably so) - and should only be done if you are chasing big peaky top end. You can do things that build that low end back in, such as cam work, head work, and the ECU...

I know from experience on simillar 2L motors that 3in NA is over the top...

but then, go ask any DECENT performance exhaust shop - rule of thumb is displacement + 125% = pipe size... so 2+125% = 2.25in exhaust

2.5 is well and good though if you are worked a bit... and 2.5 will flow a reasonable enough power for a nice peppy, but not over the top turbo build also.

p.s. er... displacement + 25%... stupid...

and thats just a rule of thumb... power goals are more in tune with how big the pipe should be to achieve highest velocity with no nominal backpressure.... i believe from memory a 2.25in will be good enough for 200 engine horsepower... 2.5 will be more than an NA 2L is likely ever going to make... 3in you are sacrificing far too much velocity.

Thanks for the info (and experience). So, it sounds like, for the time being, my choices are: a) sit tight and don't upgrade to a 3" exhaust until I go turbo, or b) get the 2.4" exhaust while still N/A and live with any limitations this creates if/when I go turbo. Sound about right?

When are you going turbo?

If you're not going turbo for a couple of years, either don't do anything, or go for a 2.25in.

a 2.5 on a turbo should still give you a reasonable amount of head room.... unless you're after 300+hp...

Yeah, that's the thing "when" I go turbo is pretty up in the air. A lot depends upon budget and time -- sometime in the near future (May or June?), this Protege is going to be my second/spare vehicle, which will make working on it a LOT easier. Right now, since it's my only vehicle, I can't really work on it myself . . . any mods have to be DONE come Monday so I can drive to work.

I am going to be shooting for about 350 whp, so will a 2.4" exhaust be a barrier to accomplishing that?

if you are that close to doing it (4 or 5 months)...just leave it until then and go to 3"

Slight clarification: my car will no longer be my daily driver in 3-4 months, I WON'T be going turbo in 3-4 months. More likely: going turbo in 12-18 months.

Would a 2.4" catback be a problem if I was going after 350 whp?

Yes unless you do a cutout. I had 2.5 turbo back with an electric cutout right below the motor.

Now I have 3" from the turbo all the way to a reducer to the 2.5 catback. With a boost activated cutout below the motor and opens at around 8psi.

So, what is the "upper limit" (in whp) for a 2.4" exhaust. How high can I go before I hit a ceiling in whp on a 2.4" exhaust? 275? 300? 325?

Might be worth looking at what other 2L turbo motors are doing with 2.5in exhausts... many chose 2.5in to keep the noise under control...

I imagine 300hp wouldn't be out of the question with other mods...but i really don't know on the FSDE sorry....