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Discussion Starter #1
has anyone put headers into a range rover classic? particularly one with the 3.5 litre v8
what brand did you use? what site? how much money?
should I be getting ceramic coated or is it not worth it?
 

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1970-1995 Range Rover Classic
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has anyone put headers into a range rover classic? particularly one with the 3.5 litre v8
what brand did you use? what site? how much money?
should I be getting ceramic coated or is it not worth it?
Thinking of doing the same for my 3.5 RRC. Having problems going uphill, all else checks out, two indie LR shops (one performed fuel pressure test, checked ignition timing, kickback cables - the works) both say all systems check out and last suspect is clogged catalytic converters. If that's the case and they have to be replaced, will just redo entire system. This is what I have:

Toddco headers - $350 (no idea if it's free shipping) but they are custom made for LR and have O2 sensor bungs installed.

Hedman 39800 - $215 seems there might be a bit of adjustment to get them to fit right because I suspect they were original to the Buick 215 (?) (comment from buyer on the linked page). Not sure about the O2 sensor bungs since there is no mention of these on the product description.

If you go ahead and install them, please post back the outcome to your 3.5's performance.

Good luck
 

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1995-2002 Range Rover P38A
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Should do, the head castings are the same as an early (pre-98) P38 that still used the 14 bolt heads, later ones dropped the lower 4 bolts but I think the casting was still the same, or at least very similar, but without the holes drilled.

The easiest way to find out would be to compare the part numbers for the gaskets.
 

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Discussion Starter #6
would they fit in the engine bay? the 3.5 litre is mounted in an offset position making it very tight to the steering column side.
 

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1995-2002 Range Rover P38A
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It is in a P38 as well. I had never realised it before but having just taken the engine out of one of mine, I realised it doesn't sit central. The P38 manifolds have an aluminium heatshield on them so not fitting that would win you another inch either side.
 

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I just looked at a P38 side by side with my 3.5 RRC, just by visual comparison I doubt the p38 left header will clear the gap between the engine block, steering box and chassis which are pretty snug together.

Also seems the p38 steering box is a little farther forward in the engine compartment giving quite a bit of room between itself and the header while the 3.5 box is a little farther into the engine bay with hardly much space between it and the manifold which is pretty high up on the block as opposed to the p38's that sweep downwards.

Was I seeing things or can anyone correct my thinking the p38 has a wider chassis compared to the RRC? When people transplant 4.6/4.0s into the classics, do they do so with headers or original manifolds?
Has anyone actually fit p38 headers in a 3.5? Please chip in just in case my visual estimations are completely off? There is a nice p38 at my local breakers yard with headers intact that I am eyeing.

*Just FYI the p38 manifold bolts need a 13mm - 12 point socket - just in case anyone gets inspired and heads out to a breaker's yard.
 

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*Just FYI the p38 manifold bolts need a 13mm - 12 point socket - just in case anyone gets inspired and heads out to a breaker's yard.
No they don't, they need a 12mm, 12 point socket. I had to buy one especially to get them out as most socket sets are 6 point at 12mm and below.
 

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I stand corrected 12mm 12 point socket.
 

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has anyone put headers into a range rover classic? particularly one with the 3.5 litre v8
what brand did you use? what site? how much money?
should I be getting ceramic coated or is it not worth it?
Argh! I bit the bullet and got Hedman 39800 supposedly for Range Rover 3.5 and the exhaust shop I took too for installation, a very well regarded shop with a lot of love from the 4x4 community here soundly rejected them. They apparently will only fit with modification or without cats because they are too long, and a "shorty" version would work best. Summit Racing where I bought them says there is no shorty version of the 39800.

The alternative the shop gave was to get rid of the restrictive cats and muffler for high flow ones and build a 2.5" y pipe and into a 3" cat-back all the way out. They seemed to think the larger pipes and high-flow cats/muffler would almost achieve the same outcome with stock manifolds as installing the 39800s. Jury is out.
 

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Discussion Starter #12
to long? like.. they reach to far down? did they fit and bolt onto your engine block without rubbing tho?
 

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to long? like.. they reach to far down? did they fit and bolt onto your engine block without rubbing tho?

The short answer is they did not even attempt. They measured, the math didn't add up, they stopped.

BUT, It has been done with a lot of creativity. Depends on whether you are doing it yourself or sourcing a shop for the job. I unfortunately have no capability to do the work myself and the shop was retaining the stock layout, so in that case the headers would not work.

A while back I found this pic online on how an exhaust build for a 3.5 would look like with the 39800s. I looked at it again this morning and noticed it has no cats.

$_57.jpg

I tried make a quick sketch of the issues:

$_57_mod.jpg

(a) is where the stock manifold ends and bolts onto the cat and then to y
(a*) is where the 39800 meet the y, it's quite farther back and if cats have to be installed they'd be that far back
(b) is to show you the stock cat position (not to scale but the point is to show the 39800 meets the y parallel to the ground further back while the stock setup has the cat in a diagonal mounting position higher up)

A creative installation though, check out this [link] towards the bottom of his build he shows his exhaust installed with the headers and you can see how much lower and further back the collector is compared to stock; and cats are way back in the setup.

The P38 manifolds are much shorter would possibly end at point (a) and quite frankly they are way better build quality than the 39800, worlds apart. I am still not sure about the P38 driver side header, but if the intention is to maintain your cats in stock position, if the P38 headers can be made to fit [???], it would be a much easier mod IMHO.
 

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Discussion Starter #14
the pictures are awesome. I am not planning on having cats in my system. but I do want the exhaust to be as high up as possible. as it doesn't scrape as much that way. so I will be looking into the p38 headers. my friend has a p38 and it has regular square type exhaust manifolds. his is a 4.6 so are the header manifolds only on the 4.9's?
 

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1995-2002 Range Rover P38A
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No such thing as a 4.9, the P38 has a 4.0 and a 4.6. The 4.0 litre is actually 3950cc and uses the same block and heads as the 3.9 Classic engine, the main change being the different engine management so it doesn't have a distributor but uses coil packs instead. A lot of Classic and P38 engine, both 4.0 and 4.6, parts are the same. If your friend has the square type manifolds like on the Classic then someone has changed them as they all had tubular ones with expansion joints in them (so they don't crack like the cast ones on a Classic) from the beginning.
 

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For those still curious about this, Gilbertd was right on the money. I took a pair of P38 headers to the exhaust shop and they are sure they will fit a 3.5 engine with slight modification to cats position.

The headers are actually pretty small without the shields, and even eyeballing them they can easily clear any engine components especially on the tighter driver's side.

Funnily enough the driver side one which I was wondering about they think is the easiest to fit and would need minimal to no mods at all to get in, while the passenger side one may need a little more modification to meet-up with cat in new position.

So are they worth it? Exhaust shop reckons the original factory manifolds are done so well and are good enough that adding headers to original factory exhaust system will have no benefit at all. But with the P38 headers there is opportunity to increase the exhaust plumbing diameter all the way back and that is where there might be "some" improvement. Well, nothing ventured nothing gained - "some" gain is good enough for me, besides I already have the headers and will paint them white! (why not).

Will post pictures and tell about it once I get it done in a bit.

Thanks Gilbertd!
 
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