Running out of go at high speed

[McCosker]

Hi my GTI seems to really run out of puff around 160-170kmh.
Is this normal that this is where these cars really start to run out of pull. the speed would have kept going up if i had more straight, but it just wasnt pulling very quickly.
Would the TIP increase the airflow at high rpm/high speeds to give it a bit more kick or am i pretty much stuck with how it goes unless i get a turbo that spools later in the rev range.

So what does everyone think?

[DaveMack]

Hi my GTI seems to really run out of puff around 160-170kmh.
Is this normal that this is where these cars really start to run out of pull. the speed would have kept going up if i had more straight, but it just wasnt pulling very quickly.
Would the TIP increase the airflow at high rpm/high speeds to give it a bit more kick or am i pretty much stuck with how it goes unless i get a turbo that spools later in the rev range.

So what does everyone think?

Obviously ... this is 'on the track' not on the street ('cos that would be illegal), yeah?

Dave

[SoVeReIgN]

They tend to run out of puff at ~5500rpm - Where ever that is on the rev range. Try changing into 5th earlier and you'll probably find it'll pull harder to ~200.

TIP helps a little, as does a good exhaust - But really the turbo isn't big enough to flow high boost at high rpms. (And if you went bigger you lose the huge low/midrange surge)

[GT3]

Assuming you're running a stock set up, many things will cause it to die off at 170, as pointed out. Generally the car has most of its power directed at the mid-range, as VW intended. I recently dynoed pre and post high flow exhaust. Without the high flow exhaust, the dyno indicated a sudden drop off of power after 160. With the high flow, it maintained peak power to 185, so that's just one example of where restrictions are in the system, particularly when you're going for peak power/top speed.

[McCosker]

Obviously ... this is 'on the track' not on the street ('cos that would be illegal), yeah?

Dave

Yes this is on the track.

And it looks like i will have to swap cogs sooner, i was pretty much running between 5-7000rpm.

I might have to look towards an exhaust. as yet i have not been keen to get one due to the massive cost that seems to be involved (some ppl talk $2k for a golf exhaust) and i like the stealth sound.

well this is somthing i will have to seriously consider now.

GT3 was the exhuast you tested a catback or turbo back? and maybe a rough cost?

[Fizz]

You can keep the Stealthiness of your exhaust while freeing it up. Get a 2.5 inch Down pipe with a highflow cat, remove the central resonator and replace 2.25 piping with 2.5 but leave the Stock OEM Rear Muffler. U'll get a deeper sound, without any boom or drone and it's only slightlier more solid sounding than Stock

[GT3]

You can keep the Stealthiness of your exhaust while freeing it up. Get a 2.5 inch Down pipe with a highflow cat, remove the central resonator and replace 2.25 piping with 2.5 but leave the Stock OEM Rear Muffler. U'll get a deeper sound, without any boom or drone and it's only slightlier more solid sounding than Stock

That's one way of approaching it, sure. However while the stock muffler will limit boom and drone, it will still restrict flow bc it's too chambered and only 2.25". If you're on tight budget, try and locate an exhaust shop with a good rep. Good rear mufflers are important too, but good ones aren't cheap. There's many options depending on your budget and results you're after.

[chris.]

go oettinger
ive got a full exhaust on mine but its quiet as (and it does little backfire pops under dexelaration )

[99gti]

I noticed you were in Sydney. Castle Hill exhaust did mine and I'm over the moon with it. For a full turbo back stainless system you would be looking at $1k approx.

[GT3]

For a full turbo back stainless system you would be looking at $1k approx.

far canal (prophetic spelling), that's cheap!!

[DUB 20V]

dont worry about a exhaust if you want more power its hardly noticable, go bigger turbo, or you wont be happy by the sounds of it, ill take you for a spin if you are in sydney, anytime you want just pm me.

[D3bb4]

Exhaust would let more flow/top end. Stock one is probably restrictive.

Bigger turbo with same exhaust wouldn't achieve much if the exhaust is restricting it.

1k for a stainless system's pretty damn good! esp. places that like to charge premium coz it's a euro.

[GT3]

go bigger turbo, or you wont be happy by the sounds of it

...he said he was reluctant to spend the $$ for an exhaust, so your advice is to spend twice that amount on a bigger turbo with a restricted stock exhaust

..do your research before you decide on an exhaust. you'll also need to come to some decision about how far you plan to go mods wise. a full 2.5" is generally the go if you want all-round drivability, ie power down low/mid-range/improved top end. if you have plans for a big turbo later, then you might consider going 3", and most of your power will be directed at peak power/top end, but the drone will drive you insane in the meantime, unless you spend big $$ on resonator and rear muffler.

let's us know how you go. ..what res and rear muffler is used in that 1k system???