tubular manifolds / exhaust system

[disco-v8]

ok im intending to get just the tubular mainfolds and Y piece to fit onto my disco 3.9 V8 (and get rid of my crappy CATS)

ive seen some cheap rangie rover ones but i need to know if they will fit my disco??????

i also intend making my own exhaust system instead of pay £500 for a rimmer bros one, then ripping it off at a pay and play day!!!!!

come on you guys with tubular manifolds help me out

cheers

[Skibum346]

Check my post in Range Rover... think there may be an emissions issue on the MOT for you to consider.

[Eeyore]

ok im intending to get just the tubular mainfolds and Y piece to fit onto my disco 3.9 V8 (and get rid of my crappy CATS)

I'll ask the bog standard engineering questions - what problem are you trying to solve?

cheers
 8)
Eeyore

[disco-v8]

basicaly there isnt any proplem.....

the only thing im trying to sort out is that theres loads of power under my bonnet but the CATSr taking it away.... plus i want a offroading exhaust that will make my ears bleed lol

[petergalileo]

Having tried this and also owning a CO tester I can confirm it is extremely difficult to get a vehicle of your age (requires  CO reading of 0.5% or less)through an emmissions test without the cats fitted.  But seeing as it only happens once a year you could make it so the cat system is refitable.

[Eeyore]

Swapping your manifolds'll make next to squat diffrerence to the noise or your performance - there are much more effective ways of eeking some more horses out if thats what you want.

Ditch the centre box on the exhaust - she'll sound better for it - it's cheaper and you shouldn't fall foul of the MOT man.  

Cheers
 8)
Eeyore

[disco-v8]

thanks for all the help lads,

but i still need to know if the rangie Y piece is the same as the disco's????

[Henry Webster]

I'm not sure, though it would be useful to know.  I do know that the non-cat y-piece is a different pipe diameter to a cat'd y-piece.

[Range Rover Blues]

Swapping your manifolds'll make next to squat diffrerence to the noise or your performance - there are much more effective ways of eeking some more horses out if thats what you want.

Ditch the centre box on the exhaust - she'll sound better for it - it's cheaper and you shouldn't fall foul of the MOT man.  

Cheers
 8)
Eeyore

Tell me more mate :D

I'm fitting a stainless tubular header system, it was a bargain S/H and I'm sick of replacing the downpipe gaskets every month, my 5.0 just spits them out :shock:

Now I didn't notice much difference when I fitted the sports system to Blue, it reves a bit more freely that's all.

[daveyravey]

Now I didn't notice much difference when I fitted the sports system to Blue, it reves a bit more freely that's all.

Thats the main reason for fitting a " free flow " tubular manifold & system.

It enables your engine to get rid of the exhaust gasses quicker, letting in more fuel/air mix into the combustion chamber. Hense it seems to rev a bit easier/quicker.
A good manifold & system should give you a few BHP increase over standard .
Had a RS 2000 a few years ago, the Janspeed man & system gave me another 10 bhp . Got bored with that & wanted more ! Fitted a kent rl21 cam & that gave another 8 bhp, on the standard 26/32 Weber carb.

[Range Rover Blues]

Yeah, but it's a bit, just a bit.  Not worth £450 odd quid or whatever, hardly worth the £230 I just pais S/H for an LSE one.  For me it's the unreliability of the standard exhaust.

ALso I've found that the 3.9 EFi exhaust is pretty efficient, the extra power of the 3.9 above the 3.5 is mainly due to camshaft and exhaust, it's bigger bore already so perhaps I'm not best placed to judge, but if I'd bought it for the performance I'd be dissapointed.

Something I found by accident, the LSE goes through one or another exhaust manifold gasket roughly every month.  This last time I snapped a stud in the manifold and couldn't be a***ed drilling it out so fitted the old one from Blue.  
Well the portings are smaller on the old one, so did Rover change the size of the exhaust track on the serpentine engine/10 bolt heads or has my engine and exhaust been reworked when the engine was tuned up?  Does anyone know for definite?

[Eeyore]

One of the huge problems with tubular systems is that the designers forget about the expansion co-efficients of the differents materials involved. Many system exaserbate the problem by using a single flange for each bank (nooooooooooo!). Best to use indivdual flanges for each port ala the original systems and fit them with a freaky taper bolt system to allow for some movement without inducing distorsion in the flange faces (there's only a couple of companies I can think of that actually offers this).

Another problem is that the designers also forget about slight problems such as pulse overlap in the exhaust flow, made all the complex because of the daft firing orders of the Rover v8. This is the key reason why a lot of tubular systems for the rover unit aren't as good as they could be. When the exhaust port is open and expecting to exhale, it gets met by a pulse of exhaust gas coming the other way.

Sadly a lot of exhaust makers are very good welders, but don't understand sufficient about gas dynamics, or how the engine will be used. How many times have you them talk about 'balanced flow?'.  :roll:

Just my tuppence, but I hate seeing folk spend good money on things they've been convinced are great by the people that make 'em or by less than objective magazines....

As has been said before, when doing owt to your cars or engines ask yourself what is the actual problem your trying to solve. Then ask yourself how will it affect everything else.  

cheers
 8)
Eeyore

[Tyke]

When the exhaust port is open and expecting to exhale, it gets met by a pulse of exhaust gas coming the other way

Not rocket science to suss out the correct length of pipe to ensure a negative 'pulse' is sat behind the valve just as it opens . . . just an understanding of the mechanics involved and a bit of mathematics . . . . . However, in practice, it starts to limit the usable rev range of a motor so most standard designs are a compromise to make as wide a usable rev range as possible . . . i dont think designers forget about the pulse timing at all . . . it's more likely an intentional thing to make the engine tractable over a much wider rev range. Not everyone wants a factory racer, in fact very few would want one if they knew how difficult they can be to drive.

Gas flowing and exhaust tuning is really good way to get more from a motor but just be aware of the narrow ranges of power that you can end up with.

[Eeyore]

. . . i dont think designers forget about the pulse timing at all . . . it's more likely an intentional thing to make the engine tractable over a much wider rev range. .

That was supposed to my point exactly!  :oops:  

The factory designers have to build the thing to work over a broad range of revs and torque demands and to meet specific NVH requirements, spending many happy hours describing pulse flows (not a job I envy). It's the after-market people I was having a pop at for building some thing that looks nice but usually fails to do the percribed job in one way or another  

As you rightly say, a bit of mod work on the standard manifolds can do wonders, if it's required.

cheers
 8)
Eeyore

[Range Rover Blues]

Well the double S system has all the header different lengths anyway.  If you want to see a proper tubular exhaust for the V8 look no further than the TVR.  They have some clever reverse cone thingy in the exhaust that stops the back pulsing, quite clever.  Expensive though :?

[Tyke]

They have some clever reverse cone thingy in the exhaust that stops the back pulsing

It actually 'stretches' the pulse and reduces it's return pressure . . . Norton was using a similar technique ('megaphone exhausts/expansion chambers') on it's racing bikes way back in the thirties . . . . gives a wider spread of usable power and helps overcome any 'peakiness' from agressive cams and valve timing.

For the average 'street tuner' simply work on the head, flowing and polishing the inlets and then sort a free flow exhaust and you will be halfway to getting a good bit more kick from your motor.

[Range Rover Blues]

Which is what you have with the 3.9 EFi system anyway, it takes some beating for performace but I find it unreliable.

[Tyke]

takes some beating for performace but I find it unreliable

One of the prices we have to pay for the increased performance . . . unfortunately . . . . but that's the way of things once you start the 'tweaking' game  :(

But get it all right and . . . . well that's another story  :twisted: