Exhaust manifolds
Discussion
Sardonicus said:
Please don't get to hung up on equal length primaries 
if your being that pedantic you shouldn't really be using the RV8 if ultimate performance is your goal there are easier ways of finding HP 
Not being pedantic IMHO(I designed & built an exhaust manifold as an engineering degree project in the 80s), was always pretty disappointed in the std TVR manifolds & was always contemplating getting a set to my own specifications made. Clive produced these at the right time for me as my std ones were cracking, they were the right price, made out of stainless & with a re-map from Jools produced over 20hp more. if your being that pedantic you shouldn't really be using the RV8 if ultimate performance is your goal there are easier ways of finding HP NickM450 said:
I have those very manifolds, not only do they add power but they sound evil, like a mash up of a angry RV8 and a screaming AJP.
Yeah, you're right, they do sound a little 'angry'.http://youtu.be/s2NdfWmzas8
griffdude said:
Not being pedantic IMHO(I designed & built an exhaust manifold as an engineering degree project in the 80s), was always pretty disappointed in the std TVR manifolds & was always contemplating getting a set to my own specifications made. Clive produced these at the right time for me as my std ones were cracking, they were the right price, made out of stainless & with a re-map from Jools produced over 20hp more.
Well maybe pedantic was the wrong choice of words 
but its not just equal length primaries is it? 
now when talking lengths collector bore size etc well that's a different story 
Sardonicus said:
ell maybe pedantic was the wrong choice of words but its not just equal length primaries is it? now when talking lengths collector bore size etc well that's a different story
Well when i had my engine on the engine dyno just after the build ,it made more ponies with the performance headers which go straight down the side .. but its not just equal length primaries is it? now when talking lengths collector bore size etc well that's a different story All that extra pipework and the Y piece must be slowing things down .
SILICONEKID345HP said:
All i`m trying to say is if TVR had made the chassis slightly wider we would nor be spending a fortune on Y pieces ,tuned manifolds etc etc and the engine bay would be alot cooler .
Compromise Daz 
bit like saying why didn't they use a SB Ford for instance yes its heavier but mounted where it is would it really make muck difference? no it wouldn't IMO and would cost considerably less to tune The forward flow manifolds are a TVR signature, for me they are very much part of the car's character and personally I wouldn't be without them even if it was possible to run the headers down the sides of the engine.
It's the little design elements like the manifolds, the central door release, the ally ball gear knob, ect ect that make the car what it is.
Remove them & you remove the car's wonderful & unique personality.
It's the little design elements like the manifolds, the central door release, the ally ball gear knob, ect ect that make the car what it is.
Remove them & you remove the car's wonderful & unique personality.
The new manifolds I am making are not intended to increase the performance, they are purely an option as a direct replacement for the existing manifolds, having no precats means the pipes only need to converge into a 3" pipe to help increase flow, and of course these manifolds will fit a catted or decatted or turbo y piece, I`ve had lots of people ask me over the last few years if I make standard manifolds as their standard ones have started cracking, or, just do not like the appearance of them, so this is my alternative.
The use of grade 304 stainless steel hygienic or dairy bends is a common cheap alternative to mandrel bending, I`d love a nice mandrel bender and all the tooling required, but investing some £30k to £50k is well beyond my limit, and how many manifolds would you have to make to recover the investment? Even having a firm with a mandrel bending machine supply you with the bent pipes is expensive, when you are quoted 3 week delivery and £20 per bend, when you stop to work out the maths and timescale its not a viable proposition unless you are placing large volume orders.
Grade 304 will polish quite nicely giving a nice neat appearance to the finished job, of course they will discolour with heat, but they will not go rusty like the standard manifolds which are made from a different grade of material.
you also have to be careful and allow for expansion and contraction of the manifolds due to the heat, as stainless steel can be prone to cracking under high heat applications, the one advantage that mild steel has over stainless steel.Grade 321 stainless would be ideal for manifolds, however getting hold of it is not easy, and as such if you do trace it, it will be very expensive, which is why nearly all manifold manufacturers use grade 304.
If the bend radius of the bends is the same or close to the bend radius used when mandrel bending the flow will not be any different if the shape and path of the tube is the same, and using gas purged tig welding any weld penetration inside the pipe will be a smooth weld bead around the inside of the joint, not lumpy bits of weld sticking out impeding the gas flow.
Equal length headers, I`ve played around with all sorts over the years and to be honest I cannot see any advantage to having equal length headers on a griff or a chim IF you are still using a standard y piece type set up, you might as well stick with what you already have, or go for the longer header option made very nicely by ACT, after all you are only merging pipes from each bank of cylinders together, if you really want to make equal length headers then to make it all work you have to look at the firing order of the engine, and pair up the cylinders that are firing a rotation apart on the crankshaft, so if you want 2 off 4 into 1 manifolds then one of these would be headers from cylinders 2,3,8 +5, and the other being from cylinders 1,4,6,+7. Then you need to calculate big the bore of the pipe needs to be for your engine, knowing, cc per cylinder,rpm etc, and then how long the header pipes should be for the performance you want to achieve, and then you sit back and think how on earth can I fit that in the tvr engine bay
(plus change over the wiring on the injectors so that the lambdas read the correct cylinders)I only made 2 sets of the tuned equal length headers, they are really only for people who are serious about getting every bhp can muster from the RV8 without going down the forced induction route, or throwing the rv8 away and fitting an LS instead, with all the bends, tube, water jet cut flanges for the primaries and secondary pipes you`ve got nearly £500 sat on the bench before you put your overalls on, and by the time you`ve finished 2 weeks later you realise they are going to cost over £2500 a set.
the ideal exhaust pipe should be straight, just look at a drag car, straight pipes out of the head, and for max top end power nice and short, but that's not very practical in a road car, so pipes need to be bent in all directions to enable it all to fit inside the car,and the diameter of the pipe should increase along the length of the exhaust system, ending up with a smaller pipe than what you started with at the engine is going to cause some problems
hope this helps, not been on here for a while,think this lot has made up for it
griffdude said:
That just sounds unreal between 0.14 - 0.17 
griffdude said:
That sounds bloody awesome! SILICONEKID345HP said:
Well when i had my engine on the engine dyno just after the build ,it made more ponies with the performance headers which go straight down the side ..
All that extra pipework and the Y piece must be slowing things down .
I like it also better when they go straight down, saves also a lot of heat under the bonnet and a shorter gas/air outlet that way.All that extra pipework and the Y piece must be slowing things down .
and ow, better for the dynamo too.
and this combo is even more perfect
180 degree headers would be nice 
but is guess no space
as for the built quality have the Y piece in the car and it is realy great.
pre cats already out of the car but what worries me most is the under bonnet temps.
have had that in stop go traffic in southern france this year and brings me
to the conclusion i will wrap anything up in the winter.
but is guess no space as for the built quality have the Y piece in the car and it is realy great.
pre cats already out of the car but what worries me most is the under bonnet temps.
have had that in stop go traffic in southern france this year and brings me
to the conclusion i will wrap anything up in the winter.
GTRene said:
I like it also better when they go straight down, saves also a lot of heat under the bonnet and a shorter gas/air outlet that way.
and ow, better for the dynamo too.
and this combo is even more perfect
At least someone agrees with me .I would have to pipes running individualy to the rear then have a H or X pipe between the two . That would sound more like a Yank motor .and ow, better for the dynamo too.
and this combo is even more perfect
If you could get the pipes down the sides you would have hundreds of options where to buy and most are mass produced .
Cliff, weld in BIG bosses so that you can supply a pair of screw in adapters...? If they want narrow or Wideband you can just swap the adapters..
I've used similar method to convert your old manifolds to pretty much the same spec as you re-welded Fatsos (bored + cut back the 'long snouted' original boss, tapped, then threaded boss inserted that has internal thread for sensor IYSWIM)
I've used similar method to convert your old manifolds to pretty much the same spec as you re-welded Fatsos (bored + cut back the 'long snouted' original boss, tapped, then threaded boss inserted that has internal thread for sensor IYSWIM)
spend said:
Cliff, weld in BIG bosses so that you can supply a pair of screw in adapters...? If they want narrow or Wideband you can just swap the adapters..
I've used similar method to convert your old manifolds to pretty much the same spec as you re-welded Fatsos (bored + cut back the 'long snouted' original boss, tapped, then threaded boss inserted that has internal thread for sensor IYSWIM)
I don't think Cliff is doing manifolds anymore, here he is demonstrating pipe size & how he prefers a tighter bore.I've used similar method to convert your old manifolds to pretty much the same spec as you re-welded Fatsos (bored + cut back the 'long snouted' original boss, tapped, then threaded boss inserted that has internal thread for sensor IYSWIM)
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