Advice on Exhaust manifold needed please.

[Blown 0]

As some of you may know already,I have a nice shiny TSR 4-1 stainelss steel manifold to fit to my G60.

After having spoken to the knowledgeable blokes at C+R they have advised that I will need to get it professionally heat wrapped or it will cause all sorts of problems.

They also said that if I want to bypass the cat,then It would be easier,and cheaper, to use a supersprint cat bypass pipe,but the reason I bought the TSR unit was for the alleged torque and BHP gains over the original.

What I need is to know whether it would be advisable to fit the TSR pipe or to have the original manifold ported to match the head and fit a bypass pipe.

If I fit a bypass will I get the same sort of results that I would get from the 4-1?

The TSR is originally for a MK2 Golf GTi 8v but it should fit the C.

Thanx in advance. :)

[Henny 0]

If you do both, you should get a better benefit than just doing either one.... 8)

 

I've had my exhaust manifold ported and have a new Miltek downpipe from JMR (16VG60) which will result in something similar to your 4branch, and I've got a full stainless system on with a custom cat-bypass and most of the tuners I've spoken to agree that this should help with the torque... 8)

 

The 4 branch should flow better than the standard manifold will, due to it's design and the length that it has to join the 4 branches together, rather than having to join to 2 in the relatively small space of the exhaust manifold...

[Dan12vGTi 0]

fit the TSR manifold your love IT :!: i had one on my MK2 8v Best tuning mod i ever did and i did a few!! you should"ve said as i might be selling it.

[Kevin Bacon 5]

Ideally a 4-2-1 is best....they're all about torque! Not many places do such a manifold though. C&R are very correct in that it will need thermal wrapping. Steel loses heat quicker than cast iron and it is the heat of the manifold that aids exhaust gas explusion. Iron manifolds are better in that respect as they don't dissipate heat-to-air as quickly. You're engine mounts need to be tip-top too as tubular steel does not take too kindly to excessive engine movement.

 

Kev

[Blown 0]

Thanks for the replies.

I have already fitted a Vibratechs front mount so (hopefully) movement shouldn't be a problem.

Just trying to decide what is the best route to take now. :?

[andycowuk 0]

Ideally a 4-2-1 is best....they're all about torque

 

 

Why is that......surely the longer primaries ona 4-1 are going to give better air flow?

[big_mac 0]

Ideally a 4-2-1 is best....they're all about torque

 

 

Why is that......surely the longer primaries ona 4-1 are going to give better air flow?

 

i think the reason is that a 4-1 creates tubulence when all four meet whereas a 4-2-1 mixes two together then mixes those two together making it less tubulent and therfore flows better.

 

think of it like rivers, 4 rivers meeting at the same point = loads of choppy watter whereas if you introduce them to each other gradually then the water becomes more managable.

 

can you tell i work in river engineering.

[andycowuk 0]

I decided to look at my book called Four Stroke Perfomance Tunning rather than lazily asking questions :oops:

 

Here is a quote....

 

The system giving the best power is the '4 into 1' arrangement

 

He goes on to discuss disadvantages such as extra weight and the space required for 4 primaries.

 

Another factor to be considered, particularly where four-cylinder engines are involved, is the effect of the 4 into 1 system restricting the power band. If good mid-range power is required, the 4 into 2 into 1 system is the one to adopt, although maximum power can be down by as much as 5-7% in comparison to that obtainable from using a 4 into 1.

 

so....thats that one clarified then!

 

I have a 4-2-1 from supersprint on mine.....dont know who else does them.

[GazzaG60 0]

if the 4 are equal length though the exhaust gas slugs should all more or less line up in the exhaust-in theory

[Kevin Bacon 5]

Yeah what your book states is basically it, 4-2-1s are good for torque and 4-1s better for top end flow....but most people are happy to trade a few ponies off the top end for better midrange pick-up....

 

K

[andycowuk 0]

Also....this is why the tubular manifold works better than the cast item......and why you should ditch the cast thing.

 

Oviously if we have a gas pressure of 20psi in the exhaust manifold when the exhaust valve opens, this will restict the gas flow out of that cylinder. On the other hand of the pressure is -5 to 0 psi then the flow restriction will be much less....*further explanation*.......look at what happens in a four-cylinder engine where all cylinders share a common manifold. The firing order we will assume to be 1-3-4-2. At the end of the exhaust stroke, cylinder number one will have created a pressure in the manifold, impeding the scavenging of cylinder 3. For this reason modified cams are a waste of time if this manifold is retained.

 

This book is mental......all this comes from the 1st 3 pages of the 22 page exhaust chapter! I bought it to read in bed, but it is so technical, it dosnt make very good bed time reading!!

[Kevin Bacon 5]

I find Playboy is a better bed time read, but what ever floats your boat :lol:

 

What does your book say about exhaust manifolds 'pulling' spent gases out of the chambers? I think you'll find cast manifolds are superior to tubular steel for that.....

 

And also....for an everyday car, a fragile tubular manifold is not viable and too expensive to mass produce......but on Ferraris and M powered BMWs for example, where every pony counts on the track, nothing less than tuned runners will do....

[andycowuk 0]

I find Playboy is a better bed time read, but what ever floats your boat :lol:

 

What does your book say about exhaust manifolds 'pulling' spent gases out of the chambers? I think you'll find cast manifolds are superior to tubular steel for that.....

 

And also....for an everyday car, a fragile tubular manifold is not viable and too expensive to mass produce......but on Ferraris and M powered BMWs for example, where every pony counts on the track, nothing less than tuned runners will do....

 

1. I sleep in the same bed as my g/f, making playboy an unpopular choice.....especially if its used as intended! :D :D

 

2. From what I've read of the exhaust chapter, the cast manifolds are in no way better.....the air leaving the chambers via a tubular manifold has momentum...so when the valve closes a partial vacum is formed 'behaind' the exhaust gases...which sucks out the next 'batch'. in a cast one, as said above, all cylinders acting on a space as close to the outlet ports as the manifold cause a high pressure.

 

3. Tubular minfolds dont need to be of the magnex type......in my mates honda civic, it has tubular manifold as standard....but is not to the magnex scale...the 4-1 joins only slightly further away from the head than the std 8v manifold does

[Kevin Bacon 5]

Cool, sounds like a good book......

 

Has your book got any recommendations for 6 cylinder engines? Mind you VR6s are unique, so they might not cover it, but I'm sure the principals are the same!

[andycowuk 0]

it goes into so much detail, that it is easy to see that no engine is the same as the next.....even between two of the same model of car!

 

Like you say, it is about the principle, they are the same.