V8 90 stainless steel big bore exhaust

[big ives]

I am looking to upgrade my exhaust and really want to get it right first time due to the cost, the engine is 3.9EFI

 

If I do away with the center box will that increase the sound level from the exhaust or am I thinking stupidly like some boy racer?

 

Should I budget for different exhaust manifolds or stick with the cast iron that’s on her?

 

Would fitting a big bore exhaust cause any other problems?

 

Last question buy off the shelf or get a quote to be manufactured?

 

As I said I would like to get it right first time…………………..thank you

 

As you can see below what I have on the old girl at the moment and what I THINK I want.

 

WHAT I HAVE ON AT THE MINUTE

RRC EXHAUST MANIFOLD CAST WITH LARGER MACHINED EXHAUST PORTS.  

RRC DOWN PIPES

RRC Y PIECE TO CENTRE BOX

CENTER SILENCER BOX TD5

FROM CENTER BOX TO THE REAR TAIL PIPE TD5 WITH SILENCER

 

WHAT I THINK I WANT

KEEP THE ORIGINAL MANIFOLDS IN CAST WITH THE MACHINED EXHAUST PORTS.

BUY NEW

RRC STAINLESS STEEL DOWN PIPES FULL BORE.

RRC Y PIECE STAINLESS STEEL FULL BORE.

STAINLESS STEEL STRAIGHT THROUGH (NO CENTER SILENCER)

STAINLESS STEEL FROM THE STRAIGHT THROUGH PIPE TO TAIL PIPE FULL BORE WITH SILENCER

[dangerous doug]

You basically have what I have. It is loud but bareable but I think it would be too much with out some sort of silencer somewhere.

 

[big ives]

Doug

when you say the same you mean what I have on now?

was thinking the same at present as I said I have two silencers in the old exhaust system

so once I get all my s*** together I might go for the same set up only in s/s bigger bore.....................................thank you 

 

 

[Bowie69]

Removing middle box makes it way too loud...

[Boris113]

I agree with above, Dad's old 90 had the same exhaust system that you currently have and it was lovely. The exhaust then rotted away and I welded in a straight through pipe as a cheap fix but it became unpleasantly noisy. It was sold shortly after so never changed back but the neighbours were relieved to see it go!

[Chicken Drumstick]

7 hours ago, big ives said:

I am looking to upgrade my exhaust and really want to get it right first time due to the cost, the engine is 3.9EFI

 

If I do away with the center box will that increase the sound level from the exhaust or am I thinking stupidly like some boy racer?

 

Should I budget for different exhaust manifolds or stick with the cast iron that’s on her?

 

Would fitting a big bore exhaust cause any other problems?

 

Last question buy off the shelf or get a quote to be manufactured?

 

As I said I would like to get it right first time…………………..thank you

 

As you can see below what I have on the old girl at the moment and what I THINK I want.

 

WHAT I HAVE ON AT THE MINUTE

RRC EXHAUST MANIFOLD CAST WITH LARGER MACHINED EXHAUST PORTS.  

RRC DOWN PIPES

RRC Y PIECE TO CENTRE BOX

CENTER SILENCER BOX TD5

FROM CENTER BOX TO THE REAR TAIL PIPE TD5 WITH SILENCER

 

WHAT I THINK I WANT

KEEP THE ORIGINAL MANIFOLDS IN CAST WITH THE MACHINED EXHAUST PORTS.

BUY NEW

RRC STAINLESS STEEL DOWN PIPES FULL BORE.

RRC Y PIECE STAINLESS STEEL FULL BORE.

STAINLESS STEEL STRAIGHT THROUGH (NO CENTER SILENCER)

STAINLESS STEEL FROM THE STRAIGHT THROUGH PIPE TO TAIL PIPE FULL BORE WITH SILENCER

The thing to consider is, are you going just for noise, or for performance.

Tubular manifolds flow better than the stock log style ones, but in all honesty, not to any amount that really affects performance on a stock RV8. What they do typically do is a thing called exhaust scavenging. The longer the primary pipes the better. This can provide a noticeable difference to the engine. Although as a rule it'll move the power curve slightly to the right... so some people may claim it feels less powerful low down. But probably is more a case of just feeling more revvy at the mid and top end.

 

The issue is, I'm not sure there are many long tube headers available for a 90. Rimmer Bros list some that look interesting, although maybe still a little on the short side. Short primary pipes will scavenge at high rpm... as in higher than the RV8 revs at. Which is why you want long primary pipes, to get the scavenging in the lower rpm.

Now, it is possible to strangle a V8 running a Y pipes and single exhaust. But the RV8 is not a HP monster, so you don't need to go overboard on anything stupid, but if you are after power, then it's all worth considering.

 

On a stock engine, good breathing mods will make the engine drive and feel nicer. More free revving and should promote some power. Their biggest gains however will be if you combine it with a cam or cam & head mods.

 

Good breathing mods, such as tubular manifolds will affect the a/f ratio, so you may need to compensate for this somehow to get the most from it and no negative effects.

 

As for the actual exhaust, really depends on your budget. Rimmer Bros sell an entire system with manifolds, no idea how good it is, but it's a one shot deal. A custom exhaust however will give you a lot more freedom. And remember, even if you do go for off the shelf or a custom exhaust, there is no reason you couldn't get it altered afterwards by a custom exhaust shop. So if it turns out to be too loud or too quiet, you could add/remove a silencer, or go for a different type/size silencer.

 

While on this, different silencer types will make it sound completely different too. Chambered silencers vs glass pack vs straight thru. And they can have a serious affect on flow rate too. Only thing you can do is some research on what you think you like the sound of.

However, I would say, no two RV8's ever sound quite the same. I used to run a cammed 3.5 RV8 in my TR7. I swapped it for a 3.9. Same exhaust including headers and same carb and inlet manifold. But they sounded completely different.

 

 

[Bowie69]

To add to the above, no I am at a proper keyboard, the RRC pipes actually flow very nicely, in fact JED re-cast them slightly larger for their uber-power engines, to get a bit more flow, acknowledging that they are a good design from factory, plus the long branches to the Y help loads.

In fact, if I were to recommend to you a system, it would be what you have, in stainless. Go up a bore size if you want, but for a 3.9 you won't see much change, but be in a good place should you go to a 4.6 in the future.

[Landrovernuts]

Ivan - try cutting the small back silencer/resonator join the pipe and retry it for noise then if you like it go for a whole stainless system in the bigger bore. The engine used to have the big bore JE manifolds, but I told you the story with them! As far as I know, as said above the RRC downpipes, are pretty good at flowing and the manifolds while not perfect are better than normal after carefull having them ported to match the heads. 

Toby

[big ives]

39 minutes ago, Landrovernuts said:

Ivan - try cutting the small back silencer/resonator join the pipe and retry it for noise then if you like it go for a whole stainless system in the bigger bore. The engine used to have the big bore JE manifolds, but I told you the story with them! As far as I know, as said above the RRC downpipes, are pretty good at flowing and the manifolds while not perfect are better than normal after carefull having them ported to match the heads. 

Toby

Hello Toby, as u can see i have time on my hands today lol

will try your tip..............................cheers Ivan 

 

[Chicken Drumstick]

42 minutes ago, Landrovernuts said:

Ivan - try cutting the small back silencer/resonator join the pipe and retry it for noise then if you like it go for a whole stainless system in the bigger bore. The engine used to have the big bore JE manifolds, but I told you the story with them! As far as I know, as said above the RRC downpipes, are pretty good at flowing and the manifolds while not perfect are better than normal after carefull having them ported to match the heads. 

Toby

A 180hp 3.9 V8 doesn't need much flow though.... I struggle to believe flow is really an issue worth addressing unless you are adding forced induction.

[big ives]

Lads

very interesting reading and thank you all 

I will now not be removing the middle box (I had thought it would have been to loud)

not really after to much more noise as she sounds nice the way she is (correct or not Toby)

as I have said many times in the past, "tinkering at landrovers is a sickness and there is as yet no known cure"

I am going stainless, but not until I read and understand more about what I am doing which is why I ask a lot of questions and research............................cheers Ivan 

[Landrovernuts]

2 hours ago, Chicken Drumstick said:

A 180hp 3.9 V8 doesn't need much flow though.... I struggle to believe flow is really an issue worth addressing unless you are adding forced induction.

Not for me to say as it does not belong to me now, but it is not a 180hp 3.9.

Toby

[dangerous doug]

I have the standard cast manifolds, some sort of tubular down pipe/de cat pipe. Rrc Y-section and the rest is 2" stainless with a 12" resonator box at the back. 

 

I should point out that 2 manifold studs had snapped in this video so it sounds a bit poo but it's loud.

 

If it's a daily drive I wouldn't recommend ditching the middle box

 

https://youtu.be/4aMwjfLh0OU

[Kierran.M.110]

I made a stainless straight through with glass packing and some semi circle shaped gates almost in the pipe for a friends series v8 that sound nice even though it's badly tuned atm, talking with the design engineer at work he said that the petrol engines need some back pressure hence tha semi circle gates 

[Chicken Drumstick]

On 2017-5-29 at 11:01 PM, Kierran.M.110 said:

I made a stainless straight through with glass packing and some semi circle shaped gates almost in the pipe for a friends series v8 that sound nice even though it's badly tuned atm, talking with the design engineer at work he said that the petrol engines need some back pressure hence tha semi circle gates 

They do not need back pressure at all, total myth.

What an engine needs is the correct A/F ratio. Freeing up a restrictive exhaust will have an affect on the A/F. If you don't tune for the increased breathing, then yes it'll perform worse. But not because it needs back pressure. Because it needs tuning.