Factory Dump Pipe & Cat Replacement

[Lawsy]

Great info mate.

I thought it would make a significant difference, but from the photo's it is just really difficult to see any length difference in the extractors. This confused me somewhat because I know how much of a difference this makes (on a 1000hp NA V8 super gas the difference is around 150 - 200hp, yes, that much.... We spoke to about 3 teams last year on this and all agreed).

Obviously nizpro know what they are doing though :D.

Awesome, keep this thread going.

[xlnt6]

Ok All, I've done a set of dyno runs @ Nizpro (same Dyno as prior to the fitment of the SMB dump pipe and cat). Here's the results:

1. On the road (seat of the pants) performance: I could notice an immediate change in the low end response of the car. It was much more responsive in the 2000-3500 rpm region. A lot more "punchiness" from a standing start, and much easire to generate massive clutch slippage !! Glancing at tne boost gauge, confirmed by initial thoughts, it appeared to be boosting much quicker and to a higher level of boost. So it's was apparent how much of the "gain" was due to the extra boost rather than the improvement in flow. Over to the dyno.

2. Dyno runs (set-up): An initial dyno run, was done and there was a overall power gain of between about 20 kw (in the mid range rpm around 3500 rpm) and about 10 kw (at the top end around 5200 rpm). But when the boost was checked on the dyno it was evident the originally capped boost (see Boost1a.jpg) of 10 psi in the mid-range and 12 psi above 5000 rpm was no longer being maintained. It was now boosting around 13psi in the mid-range. So what this was indicating was the dump pipe and cat did reduce restriction, but how much power gain was due to the greater boost vs dump-pipe & cat flow was unclear. Boost was then wound down to re-instate the initial boost profile. A dyno run was done and the result showed a small improvement in power over original (see Power1a.jpg for original). Now I didn’t think to print these out (as I was more interested in the potential increase in mid-range and high end power with the high boost profile). I’ll try to get a copy and post them. But for the record, it was only about 10rwKw and top end power was pretty much the same.

3. Dyno runs (Final): The end result was as posted in Power2a.jpg, Torque2a.jpg and Boost2a.jpg. Boost is currently capped at about 15psi (the wastegate is having difficulty flowing the required amount of bypass and the result is a wavering boost profile). Top power was 363.3 kW, but extra margins of safety capped this at 358.9kW. What is interesting is the boost (Boost1a vs Boost 2a) and the way it builds up between 2000 and 3000 rpm. Comparing the graphs shows the Boost2a builds quicker (by a small but consistent margin). This can be felt in the drivers seat as a more responsive car. This is due to the improvement in the dump pipe (ie faster turbo spool). Also now the car is not held back by the drivechain (ie T56/twin plate), the boost was allowed to peak much earlier and the resulting change in torque is huge. Torque is now reaching about 875Nm (note: Torque2a figures need to be converted back to the flywheel to derive this figure).

Dyno charts:

Power1a vs Power 2a: Power 1a shows the stock car dyno run (before Nizpro Stage 2) vs after fitment of Nizpro Stage 2. Power 2a shows Nizpro Stage 2 vs Nizpro Stage 2 + Dump Pipe + More Boost (and re-tune). Note how much power is gained in the most important rpm range 3000-4000 rpm. It’s greater than the outright power improvement.

Torque1a vs Torque 2a: Same as Power1a vs Power 2a, but for Torque. Now that boost in no longer capped in the mid-range, the true torque potential is achieved. Tyre fryer !!

Boost1a vs Boost 2a: As discussed above, boost was originally capped due to driveline strength with the T5. Now with the T56 this no longer applies and boost is allowed to reach 16psi (set at 15psi, but due to wastegate flow it wavers around !!!). The boost curve shown here actually corresponded to the 363.3kW run (which is not shown here), but the 358.9 kW run was similar (just a bit smoother and less wavering and held closer to the target of 15 psi).

Summary: So what this shows it is possible to achieve +300 rwkW with an OEM exhaust system. And changing the dump pipe and cat does have a tangible gain in power and torque (when all things are equal, ie same boost profile), but it was only worth about 10 rwKW when running a lowish boost profile (ie original 10psi/12 psi profile). What was indicated to me, was that at above 350 rwKW the dump pipe and cat do make a difference. Simon has indicated that the top end power was higher (about 10-15 rwkW) than normally attributed to 15 psi boost set-up. This matched up to SMB stating that the dump-pipe and cat make a difference above 350 rwKW. So if you running less than 330/350 rwKw you may want to consider saving your cash and sticking with the OEM exhaust.

Now, please don’t flame me with your disbeliefs etc, I’m not interested. But relevant and topical posts will be entertained !!!

[xlnt6]

Here's the Torque charts...

[xlnt6]

And finally the Boost Curves.....

[macka'sxr6t]

Great info and feedback well done

Interesting to see the 2 different boost graphs. I like the 2nd one. 1st one is strange how it has a flat spot in it.

Is this from the way the car was tuned or waste gate problems or as a direct response to the new exhaust.

macka

[bcl]

Good report Robin.

It's understandable why Nizpro give precedence at stage 2 level of Intercooler and efficient inlet over exhaust system.

I'd also ask Simon to replace your wastegate spring to a stronger item.... which is what I did, as the standard spring is too weak for higher boost levels. Also, your exhaust housing and swing valve may need some modification to flow better.

Brian

[F6 UTE]

V good thread.

The wastegate mod, is this what aps does? increase the size?? or mod the spring or both.

Cheers..

[bcl]

V good thread.

The wastegate mod, is this what aps does? increase the size?? or mod the spring or both.

Cheers..

<{POST_SNAPBACK}>

APS do both, but at stage 3 level; it is a common mod for turbo cars.

The Garrett turbo is a hybrid, and mismatched for high boost levels, with a relatively small exhaust housing compared to the compressor. You can do some porting on the exhaust housing and replace the swing valve.

APS replace the wastegate arm with an adjustable item; I've used that type on cars before, but you need to get the tension just right... tighten it too much and you might have an adverse effect on wastgate opening; I prefer just to change the unit with one with a stronger spring.

A cruder method/option is to shorten the arm to increase tension by a cut, trim the length in the middle of the shaft, and reweld.

Brian

[F6 UTE]

V good thread.

The wastegate mod, is this what aps does? increase the size?? or mod the spring or both.

Cheers..

<{POST_SNAPBACK}>

APS do both, but at stage 3 level; it is a common mod for turbo cars.

The Garrett turbo is a hybrid, and mismatched for high boost levels, with a relatively small exhaust housing compared to the compressor. You can do some porting on the exhaust housing and replace the swing valve.

APS replace the wastegate arm with an adjustable item; I've used that type on cars before, but you need to get the tension just right... tighten it too much and you might have an adverse effect on wastgate opening; I prefer just to change the unit with one with a stronger spring.

A cruder method/option is to shorten the arm to increase tension by a cut, trim the length in the middle of the shaft, and reweld.

Brian

<{POST_SNAPBACK}>

Cheers, any ideas on one that's available ( spring/arm setup?? ) when u say adjustable arm, do you mean one that's threaded on the end?? I had one of those on my last car..

Was thinking of doing something to the wastegate on the tornado when it gets the treatment, also thinking of running around 15/16psi..

thnx..

[bcl]

Cheers, any ideas on one that's available ( spring/arm setup?? ) when u say adjustable arm, do you mean one that's threaded on the end??

<{POST_SNAPBACK}>

Not really, many good turbo shops could help.

Yes.