49 minutes ago, siteunseen said:

Pardon my ignorance but I'm trying to learn something here. A straight 6 motor will perform better with dual pipes like a V block? Or is  it a preference of sound?

Again, I'm trying to understand so no need to give me negative responses. Don't waste your time typing. 

Thank you. Cliff

I understand now after I thought for 2 seconds.

The header splits 3 & 3. Sorry.

The header never joins the front 3 and back 3 primary pipes...the system is 3 and 3 all the way through, at least that's the config in the SG system.

4 hours ago, siteunseen said:

Pardon my ignorance but I'm trying to learn something here. A straight 6 motor will perform better with dual pipes like a V block? Or is  it a preference of sound?

Some may argue differently and Nissan made different header types. There is no 'better' , no 'best', simply what suits your engine (size and specification) AND the style in which you drive (read here use of the car ie street, street 'n track, competition track...) and then to really through in the more personal variables : budget and also personal taste and preference.

 

7 hours ago, Sean Dezart said:

I beg to differ : twin pipes will perform differently (regardless of cross-sectional areas) compared to a single pipe - I thought that we had discussed and agreed upon that and why Nissan offered it as stock on S20 engined S30s (and Skylines) and as an option on other S30s.

 

39 minutes ago, Sean Dezart said:

Some may argue differently and Nissan made different header types. There is no 'better' , no 'best', simply what suits your engine (size and specification) AND the style in which you drive (read here use of the car ie street, street 'n track, competition track...) and then to really through in the more personal variables : budget and also personal taste and preference.

 

There certainly is a "better" if we can agree that better means more torque. Joining all the cylinders increases the scavenging effect (dropping pressure at the exhaust port of the next cylinder), thus increasing volumetric efficiency which is directly proportional to torque. The effect is tuned with some thought behind pipe lengths, collector locations, etc. The physics remain the same, whether you have 6 individual pipes or just one.

Sound, look, personal taste, that's all subjective and a perfectly good reason to choose what you like.

There has to be a performance variable, a decent one or factories wouldn't design systems like that, which seem common on IL6 engined cars.

Pleased to see you're happy with the Spirit Garage system, its a good looking system, nice to see one that follows a factory'esq route.

9 hours ago, LeonV said:

There's really no other reason to split the pipes in two all the way to the back of the car, other than sound.

So when Nissan did it on their S20-engined cars and on their works race (S20 and L6 powered) and rally cars (L6 powered) and the likes of BRE and Bob Sharp followed suit on their race cars, you believe it had no reason other than "sound"?

10 hours ago, HS30-H said:

So when Nissan did it on their S20-engined cars and on their works race (S20 and L6 powered) and rally cars (L6 powered) and the likes of BRE and Bob Sharp followed suit on their race cars, you believe it had no reason other than "sound"?

Poor phrasing on my part. There's no other reason *besides packaging* and/or sound to split the pipes.

Here's an in-depth thread on exhaust design: http://forums.hybridz.org/topic/81941-exhaust-tube-sizing-i-did-your-arithmetic-for-you/

I don't know why Nissan or Bob Sharp did what they did. I'd be very interested to hear about their design process. Pete Brock was in town this past weekend but unfortunately I was away...

48 minutes ago, LeonV said:

Poor phrasing on my part. There's no other reason *besides packaging* and/or sound to split the pipes.

Here's an in-depth thread on exhaust design: http://forums.hybridz.org/topic/81941-exhaust-tube-sizing-i-did-your-arithmetic-for-you/

With all respect to those on the thread, that thread doesn't constitute 'the answer'.  The fact that Nissan and numerous factories did it back in the day, bmw did with with most of their IL6's, maclaren's v12 did double that when it was after all out weight savings etc.  Its not as black and white as a 3 page thread.

4 minutes ago, Jason240z said:

 Its not as black and white as a 3 page thread.

Yep - like I said, there is no best or better, there is what suits you, your engine, budget, hearing aid and driving style......and even then we might criticise your taste anyway  !

We hear the same re blocks and heads - which is 'best'......how long is a piece of string ?

 

What we all like, I'm sure, is choice and luckily for S30s, there is plenty of that.

Spirit Garage header to tailpipe system is on the car.  I decided to replace all the head studs so that slowed be down a bit, the MSA kit I used previously I was not overly happy with so I went to Nissan, all good to go.  In my case the header's first primary did indeed contact the steering shaft so it had to be worked for clearance, it is likely designed for a RH drive car, understandably.  The crankcase breather has to be cut down and tapered for the header to fit or you can use one off a 280.  The rest of the kit's fit an finish is awesome and it is tucked up nicely.  I have an '87 Turbo CLSD R200 and the pipes fit around it without any issue. 

One thing I haven't resolved yet is a heat shield for my SU's...the stock heat shield was already cut in one spot to fit the Stahl and unless someone can direct me to a better solution, it seems I will have to so a bunch more cutting and bending again so I am open to any suggestions.  I have searched and searched but all that seems to be out there are ones for triples...thanks guys.  

Edited April 16, 20186 yr by ollie

Nice update - thanks.

This stuff works very well from top to bottom : https://www.demon-tweeks.co.uk/motorsport/heat-shielding-protection/nimbus-gii-heat-shield ok, it'll hide your new, shiny header but what counts is that all works well together. The next step forwards for more performance is to completely isolate the intake side from the radiator pushing hot air into that side !