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1995-2002 Range Rover P38A
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2 Posts
Discussion Starter #1
Anyone know of anybody fabricating bigger headers for the 4.6 Gems engine? I'v just bored out to 5 litre and here in NZ we can ditch the cats, so I'm thinking of a better header setup. Already running Janspeed SS back end mufflers and tail pipes. Thanks.
 

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You may be on your own here with a custom fabrication. We've had the topic of headers come up a few times but it is such an obscure mod on P38s there just doesn't seem to be any commercial call for them. What year P38 are these going on?
 

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JACK'S GRANDAD
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9,242 Posts
Having built quite a few 4.6's etc, I'm inclined to say the factory manifolds are not very restrictive.
Port match the heads to the manifolds and gaskets and call it good.
I also know of nobody that makes them
 

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1995-2002 Range Rover Classic
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1,413 Posts
rpi engennering, or rimmer bro's maybe, they are some of the uk based rover specialized businesses whom have expanded engines to 5.0, thus I imagine they have made them breathe better as well.
 

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1995-2002 Range Rover P38A
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Discussion Starter #5
Thanks for that. How did you get a 6.0 L to breathe better? I've just acquired another block with some slipped liners that I'm thinking of taking to 6.0 and swapping for the 5.0 I think there is just enough meat in the top hat liners to do it. Also, would you mind sharing the spec of of your 375hp daily driver? Or pointing me to the correct blog. Cheers.
 

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John, who are your asking that of? No body has brought up a 6.0L in this thread... only that UK companies readily bore to 5.0.

you also have not answered what year P38 you are working with nor have you added your Rover info to your signature.
 

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1995-2002 Range Rover Classic
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another option for custom headers may be someone such as summit, jegs, D&D fabricatiions, there is a buick spacialized shop in new jersey their name skips me or, as last resort a local speed shop.
 

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1995-2002 Range Rover P38A
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28 Posts
You could get yourself a copy of “Scientific Design of Exhaust and Intake Systems” by Smith & Morrison. ISBN 0-8376-0309-9.

Work out the size, length and junction points you need and get a custom exhaust builder to fabricate to fit these dimensions as close as possible. That will make all the effort you have done worth while.

I have contemplated doing this on my 4litre, but given I use my magic carpet to tow my race car it might be overkill!!

Good luck.
 

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1995-2002 Range Rover P38A
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the 6 litre you refer to is an LS powered (chev motor) not a rover motor , if you want to do that you will have to get Martin to do another run off the shafts that he used . good luck with that?
 
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