Exhaust diameter?
- Thread starter sujomatt
- Start date
yea im thinking 2.5" exhaust is the biggest ud really need even with a gt25 or gt28 turbo
laborsmith
New member
I believe the 1.8 is 2" and the 1.4T is 2.25."
Solo Performance is scheduled to ship a cat-back exhaust to me Tuesday, so I should be able to give a more certain answer next week.
Laborsmith
Solo Performance is scheduled to ship a cat-back exhaust to me Tuesday, so I should be able to give a more certain answer next week.
Laborsmith
Thank you for the clarification, was a bit confused by 2"
Look forward to seeing what u get next week
opcorn:Dave@ddmworks
Supporting Vendor
Not sure of the 1.8L yet, but the 1.4L has the following dimensions -
The front of the secondary cat is 2.125" OD
The back of the secondary cat is 2" OD
The rest of the exhaust behind the secondary cat is 1.75"
So the stock 1.75" has an internal area of 2.07 sq/inch (with wall thickness taken into account) and our 2.25" system has an internal area of 3.54 sq/inch or about 70% larger.
laborsmith
New member
Wow, Dave. I would say that counts as a more certain answer!
Laborsmith
Laborsmith
i will have my 3in turbo back on in a week and will be on dyno for testing to see how car reacts to to size. i know some are againest this but we will see what happens. i think most will be suprized at the #s because i have never seen a turbo car have major problems from a let better air. and yes i know about the self learning. i already have a couple ecotecs running alot bigger piping with no problems but big power.
Danny5
Its over 39000!
Heh, was going to say that I am pretty sure the exhaust is 2", as thats what my muffler shop installed when I removed the resonator.
Thanks for the heads up Dave!
SonicChris
Banned
If your tuned, then the self learning shouldn't be an issue. Neither will the 3in, but if your not tuned for an exhaust that big, it's kind of a waste. Yeah, you may see some power gains, but not as much as you could with tuning.
Has anyone seen what kind of mpg gains can be had when opening up the exhaust? I wnt more power, but better efficiency would be icing on the cake. The turbo diesel guys say you should add as much exhaust as you can fit and afford. It's only a 13ft long car so the expense is less.
laborsmith
New member
I have not noticed an appreciable difference in mpg since installing a freer flowing increased diameter exhaust, but I am not a good source as I do not try to keep track except for short periods, such as checking highway mpg while on a freeway.
What I have noted is a slight increase in the engine operating temperature, and that may relate to fuel economy, but there again I do not know. After putting the heat extractor hood on the average tempt dropped to 197 plus or minus 2 or 3 degr3es and now with the exhaust it around 200 plus or minus 2 or 3 degrees. Before the hood it was up to around 210 degrees.
I believe one member with a 1.8 and one other with a 1.4T (which I have) have also gone to 2.25 and perhaps they are better at record keeping than I am.
Laborsmith
What I have noted is a slight increase in the engine operating temperature, and that may relate to fuel economy, but there again I do not know. After putting the heat extractor hood on the average tempt dropped to 197 plus or minus 2 or 3 degr3es and now with the exhaust it around 200 plus or minus 2 or 3 degrees. Before the hood it was up to around 210 degrees.
I believe one member with a 1.8 and one other with a 1.4T (which I have) have also gone to 2.25 and perhaps they are better at record keeping than I am.
Laborsmith
laborsmith
New member
No.
In my opinion, 3" would be overkill, because you would be running too lean.
Above answers based on reading too many threads on this subject in a variety of performance car forums, not personal experience.
I am also thinking 2.25 was a direct hook up, at least to the cat.
But running lean would scare me, so the need for a tune would be exponentially increased.
Laborsmith
In my opinion, 3" would be overkill, because you would be running too lean.
Above answers based on reading too many threads on this subject in a variety of performance car forums, not personal experience.
I am also thinking 2.25 was a direct hook up, at least to the cat.
But running lean would scare me, so the need for a tune would be exponentially increased.
Laborsmith
BrentnKC
New member
In my experience as a Trifecta reseller working with folks before the car is retuned an aftermarket exhaust may make more HP higher in the rpm range but lose TQ in the low end. When retuned the power can be increased on the low end.
Especially, for Turbo cars the opened exhaust reduces back pressure subsequently increasing spool up time. I am guessing a low end timing increase will help but will have to defer with Vince on that one.
More relevant, as a dealer for DDMWorks Sonic parts, I installed their cat back exhaust. The fit and finish was excellent and fit right up to the First high-flow cat downpipe. I installed with a resonator but without the muffler. The sound is good in my opinion and not too loud. My "butt dyno" felt a loss in low end TQ and increase in top end power. I am working with Vince to review and fine tune and I will let you know what we find out. I will also try and get a real Dyno soon with this package.
As far as my understanding, aftermarket air intakes can cause leaner than stock conditions and degradation of idle quality. This is another good application for a tune.
DDMWorks new intake that is in beta testing does not create a lean A/F ratio.
Especially, for Turbo cars the opened exhaust reduces back pressure subsequently increasing spool up time. I am guessing a low end timing increase will help but will have to defer with Vince on that one.
More relevant, as a dealer for DDMWorks Sonic parts, I installed their cat back exhaust. The fit and finish was excellent and fit right up to the First high-flow cat downpipe. I installed with a resonator but without the muffler. The sound is good in my opinion and not too loud. My "butt dyno" felt a loss in low end TQ and increase in top end power. I am working with Vince to review and fine tune and I will let you know what we find out. I will also try and get a real Dyno soon with this package.
As far as my understanding, aftermarket air intakes can cause leaner than stock conditions and degradation of idle quality. This is another good application for a tune.
DDMWorks new intake that is in beta testing does not create a lean A/F ratio.
