NC 20BPP Time Attack / Track Car - Build Thread

Postby **orx626** » Sat Aug 31, 2013 7:29 pm

Exhaust time!

Starting with the headers....it is very important to have the primary pipes exit the engine in the longest possible length of straight pipe before bending and heading rearward. The NC certainly accommodated this requirement. Everything is just tacked togther at this stage.

Heading rearward to the first flange. The primary pipes will extend as far rearward as possible before collecting into a single 3.5" tube.

The extra primary tube length will be trimmed to suit the flanges final position.

Removed from the engine for welding out (except the rear flange).

The rear section is next.

Cheers,
Danny

Postby **NitroDann** » Sat Aug 31, 2013 7:48 pm

Those are tidy, did you get the runner length you wanted?

Dann

Postby **orx626** » Sat Aug 31, 2013 7:52 pm

NitroDann wrote:Those are tidy, did you get the runner length you wanted?

Dann

Yep, I'll get some more photos up over the next week.

Cheers!

Postby **Okibi** » Sat Aug 31, 2013 8:10 pm

Postby **orx626** » Tue Sep 03, 2013 9:20 pm

With the front section of the exhaust system sorted, the focus returned to the rear section. Then we just have to join the two sections together.

The trusty zip ties have been replaced!

The merge collector clamped in place at the entry to the first muffler....

Another hanger was positioned at the front muffler and attached to the PPF....

Since the last photo of the NC's rear end the lower section of the rear bumper has been removed.

With the 4" dumpy in place! :twisted:

From underneath....

Cheers,
Danny

PaulF · Postby **PaulF** » Tue Sep 03, 2013 9:29 pm

The diameter seems to step up immediately after the collector and before the first muffler. Why is that? If the diameter it steps up to has the most ideal flow, wouldn't the end of the collector become a restriction?

Obviously there's good reason for it, I'm just curious.

Postby **NitroDann** » Tue Sep 03, 2013 9:41 pm

At the collector only one cylinder at a time is firing and flowing through, after the collector the exhaust gas is homogenous from all 3 cylinders.

The step up at the very rear is just for effect.

Dann

Postby **orx626** » Tue Sep 03, 2013 9:49 pm

Fair question Paul.

The minimum diameter at the collector is just over 3" and then it steps up to the 3.5" rear section. At the 3.5" diameter the transition of the three 2" primary pipes was compromised. What I mean by this is that the collector length would have been substantially reduced and we deemed this to be more important than the slightly smaller diameter that resulted. The "restriction" is over a very small distance. I guess the proof will be in the pudding when it finally gets on the dyno.

Cheers,
Danny

Postby **orx626** » Tue Sep 03, 2013 9:53 pm

NitroDann wrote:The step up at the very rear is just for effect.

Yep...the 4" dump was done because you can't buy 3.5" mandrel bends in stainless steel.

Otherwise it would have been a 3.5" dump.

Cheers,
Danny

16bit · Postby **16bit** » Wed Sep 04, 2013 10:24 am

looks mean.

anyone in time attack doing exhaust blown diffusers? or not enough exhaust gas velocity.

Postby **orx626** » Wed Sep 04, 2013 10:45 am

16bit wrote:anyone in time attack doing exhaust blown diffusers? or not enough exhaust gas velocity.

I'm not up to speed with exhaust blown diffusers James...but I'll hazard a guess that as the cars get heavier the exhaust flow would need to increase as well. My NC does not have the power (exhaust gas flow) to weight ratio of an F1 car and I don't of any that would even come close.

I'm building the aero package for the NC to the current WTAC open class rules.

Cheers,
Danny

little decks · Postby **little decks** » Wed Sep 04, 2013 11:01 am

orx626 wrote:
16bit wrote:I'm building the aero package for the NC to the current WTAC open class rules.

So still very insane? haha.

Just had a look at some of the picks of Suzuki-sans S15 and the RE Hurricane FD, pro class will not relent in dropping my jaw every year.

Postby **orx626** » Wed Sep 04, 2013 11:51 am

little decks wrote:So still very insane? haha.

I'm hoping for subtle! :wink:

little decks wrote:Just had a look at some of the picks of Suzuki-sans S15 and the RE Hurricane FD, pro class will not relent in dropping my jaw every year.

Indeed. I know Andrew Brilliant has been testing with Under Suzuki last week. He'll be another one to watch this year.

Cheers,
Danny