GHL turbo back?

[dubspeedGTi]

I was thinking of getting a GHL exaust turbo back. What I would like to know is what diameter is better (3 in or 2.5 in). I was talking to one guy here and he recomended the 3 in he was actualy the one that recomended the GHL in the first place. What do you guys think? I also read a thread about getting the down pipe before the rest if you can't get the whole thing together, as will proablly be my case $$? What do you think of that?

[Kor]

Re: GHL turbo back?

I was thinking of getting a GHL exaust turbo back. What I would like to know is what diameter is better (3 in or 2.5 in). I was talking to one guy here and he recomended the 3 in he was actualy the one that recomended the GHL in the first place. What do you guys think? I also read a thread about getting the down pipe before the rest if you can't get the whole thing together, as will proablly be my case $$? What do you think of that?

IMO larger diameter is always better.

I have read articles for getting just the DP or just the cat-back and both scenarios usually cite performance gains... so getting one before the other in either order is fine.

[Mr. Burns]

Re: GHL turbo back?

3" = louder

[NeonGTI]

Re: GHL turbo back?

3. 3. 3. 3. 3. 3.

Once more..

3.

Once the gasses are past the turbo you want them gone as quickly as possible.

A 3 also gives you more room to grow than a 2.5. If you are concerned about noise then get them to weld another resonator in the chain.

[Klobi-One-Kinobi]

Re: GHL turbo back?

I thought there clearance issues with a 3" dp.

[NeonGTI]

Re: GHL turbo back?

I heard that too, and not just about the GHL. I haven't heard anything lately though, which would lead me to think they made some revisions for fitment.

[QuA]

Re: GHL turbo back?

Hmmm I remember mentioning Muffler inlet sizes. Lets say you have 3" DP and Catback but a 2.5" inlet or even a 2.25" inlet would that give you a noticable performance hit?

[Kor]

Re: GHL turbo back?

Hmmm I remember mentioning Muffler inlet sizes. Lets say you have 3" DP and Catback but a 2.5" inlet or even a 2.25" inlet would that give you a noticable performance hit?

Restrictions are bad, especially if they are not smooth ones. A 3" cat back with a 2.25" muffler inlet is a problem.

[Tuna]

Re: GHL turbo back?

Hmmm I remember mentioning Muffler inlet sizes. Lets say you have 3" DP and Catback but a 2.5" inlet or even a 2.25" inlet would that give you a noticable performance hit?

I feel as though I should say that some exhausts are actually ENGINEERED to have a step up or step down to increase torque down low. I would assume that the wrong combination could also have negative effects, but that's just my opinion. I would think talking to someone that knows exhausts would know and if you do step down the best way to do it.

Jason

[NeonGTI]

Re: GHL turbo back?

Yes, there are stepped tube headers available and they do work nicely - I had one on my NA Neon for a while.

Once a turbo is in the mix that all goes to poop.

The goal is to maximize flow while maintaining exhaust velocity and conserving heat to get the turbo spooling. Once past the turbo you want it gone ASAP.

A properly designed and sized header will promote exhaust scavenging (basically causing a vacuum effect and helping suck the forthcoming exhaust using the velocity of the previous exhaust pulse) and thus make more power. This effect, however, is minimized on a turbo car because the turbo collects and compresses the exhaust pulses and essentially makes them one big pulse.

Back pressure in the exhaust past the turbo will cause the turbo to slow down as the gasses cannot evacuate the turbine quickly enough to sustain the momentum of the turbo. Backpressure can also cause unwanted heat transfer to the turbo. Hot exhaust gas = good, hot turbo = bad.

(Hot Carl = worst, but that is another story)

There may be some argument that the large downpipe will cause a loss in torque in some areas of the powerband. This can be true as with a smaller exhaust the increase in pressure in the exhaust system can allow the exhaust gasses in the cylinder a teeny bit more time to act on the piston but the positive effect lessens with mods, flow and RPM. If you MUST have that extra lb-ft of torque at low RPM then you should stick with the 2.5 or the stock downpipe and save your money to buy a VR6 or a TDI.

A stepped design might give you part of that extra lb-ft back, but I wouldn't count on it until I saw a dyno. I've seen plenty of NA drag cars and NA race cars with stepped headers but I haven't seen many turbo ones.

[Kor]

Re: GHL turbo back?

Good comments. 'nuff said.

[QuA]

Re: GHL turbo back?

Sweet. I changed my muffler and its a 2.25" inlet now. so im 2.5" turboback but my damn inlet is 2.25" Shizah.

QuA

[Bighead]

Re: GHL turbo back?

I've had both. 3 and dont look back

[Flanders]

Re: GHL turbo back?

3" and you'll need stiffer engine mounts so it the dp doesn't rub against the heatshielding in there.

2.5" and you may get away without the engine mounts...

Regardless of what anybody tells you, there WILL be a slight increase in cabin vibrations with new engine mounts!

[1.8Trip]

Re: GHL turbo back?

If you do get motor mounts, I recommend the Forge ones. They are just the right stiffness for a street car.