TT Exhaust Review + Dyno Results

[Kor]

Well, I got my exhaust installed. For those of you who don't know, its a Brullen 2.5" Downpipe mated to a Techtonics Tuning 2.5" Cat-Back.

There was a LOT of traffic on my way home at 6:00pm so I have not really driven it. This is only a preliminary review.

I will start with the bad news.

The Cons:

- The exhaust is loud. I mean it.

- I am getting MAD surge again. I don't know how I am going to fix this.

- The fitment is bad. C1 is going to get a custom piece made and I will go back in a couple of weeks to have it refit. Right now it is hanging *below* my valence (and I have a cutout).

The Pros:

- The performance is GOOD. I mean it.


Summary:

I can get used to the louder tone, and of course I can always turn my stereo up louder. The fitment issue will be fixed by C1. I need to figure out how to fix the surge. Its really bad.

Dyno Summary:

As we have already discussed, surging generally doesn't effect Torque too much but it makes your horsepower quite a bit lower. From the amount of surge and from the curves on the dyno plot, I would estimate another 15 hp will be gained from fixing the surging. This is not just a seat-of-my-pants estimate, you can use a pencil and extend the hp curve of the graph where it drops due to the surging.

Numerical results:

I really have made you wait for these, haven't I?

Horsepower: 185.1
Torque: 256.0

Conclusions:

I should easilly be able to reach 200hp and 250+ ft/lbs of torque if I can solve the surging problem. However, even with severe surging the car is much faster than before. This is not a fluke.

Discussion:

I need ideas about how to reduce the surge! You should see my boost gauge, its crazy.

[R_Ethug]

thanks kris.. your numbers are what our cars should be pushing.. i have no idea why peters weren't like this but yours are fantastic.. i hope to acheive your results with a revo setup. I'll have to hear your exhaust and compare it to my brullen..
shitty to hear about the surging.. switch chips? i dunno

[Holksvagon]

nice #'s kris.... very impressed

[Kor]

Looking at my boost gauge, I must be requesting a TON of boost... or something. It is spiking really high. Like off the scale high. I don't know why I am getting such huge spikes now.

I am not exactly sure what it could be, but I have already tried the N75 thing so... I will obviously need to try other modifications... I am not too optimistic for a quick fix but I will say that I am confident I can fix the problem in the long run.

Edit: Maybe I just killed one of my sensors... it was already kind of flakey... MAF?

[Simon]

hot numbers man! TT was definately on my short lists of possible exhausts, its always been known to be loud though.

where did you buy it from and how much did it set you back if you dont mind me asking?

[Kor]

I bought it at C1, it was a special order so I had to wait a while and did not get a discount. I don't really want to post the price until my wallet heals, but if you call C1 they can probably tell you over the phone.

[1.8Trip]

Great review Kor! Shitty to hear about the surging though, but I'm sure you'll figure it out. When you do, make sure you post the solution.

[QuA]

absolutely HOT! Very good write up kris. Every car is different. But just like we talked about before..... you got a freak car dude!

QuA

[Smartiepants]

Niiice

[Kor]

I have a well thought out (no fluke) plan to install an adjustable air pressure regulator inline with my N75 wastegate controller. I will be picking it up later this week. I am fairly certain that it will work.

If it does work, it may be a better and possibly cheaper way to eliminate surge.

Edit: Anyone know where I can try to find a 0-30psi inline adjustable air pressure regulator?

[QuA]

Hey Kor does that mean you are selling a N75 "J" Valve? I want it!!!

QuA

[Fluidic Digital]

Excellent review Kris -- just excellent.

You know what... and Sean can back this up -- I think your injectors are running at 105% capacity. That's it -- they are maxed out. Your car is requesting more fuel then it can deliver -- thus the impression of surge.

I thinking of selling my Brullen and buying something a little more... high performance.

Again -- excellent review -- as always! :thumbsup:

Peter

[Kor]

Mike: After I build my pressure regulator thingy I will still need an N75 to control the boost under partial throttle. So I will probably keep my J. But I will try both valves, there is a small chance I won't need it if the F perfroms better. I am fairly excited about the pressure regulator idea.

Peter: Not so sure about the injectors theory. Exhaust system does not really add more air to the cylinders during combustion. I would need to be getting fairly substantial boost levels compared to stock in order to max out the injector capacity. My own theory is just that reduced backpressure is increasing the flow through the turbo creating a higher initial "spike". Surge is caused by boost spiking too high and the ECU deciding that it needs to take countermeasures.

As for the exhaust, it is a very good performance product. But before you buy one you should listen to my car, it may be too loud for some people. There is nothing stealth about the sound of my car now! Also as I mentioned the fit is REALLY bad but hopefully C1 will fix this.

[Fluidic Digital]

Originally posted by Kor
Peter: Not so sure about the injectors theory. Exhaust system does not really add more air to the cylinders during combustion. I would need to be getting fairly substantial boost levels compared to stock in order to max out the injector capacity. My own theory is just that reduced backpressure is increasing the flow through the turbo creating a higher initial "spike". Surge is caused by boost spiking too high and the ECU deciding that it needs to take countermeasures.

Dude... with a chip -- you are VERY close to running the injectors to max. The injectors (trust me I know... literaly) are not very big -- part of surging is not having enough fuel for a certain PSI level. In turn, so the motor prevents leaning out -- the boost is automatically lowered and power is reduced.

If I keep the 1.8T -- I'm going to experiment with injectors.

Peter

[Boy Racer]

Cant the injection pulse width be monitored in Vag Com?