Janspeed manifolds - Worth the money?
 

Subject says it all really.
Are the Janspeed manifolds for the 180 worth the money?

1. Is it a good and noticeable performance increase?
2. Is the increase all through the rev range or only in certain ranges?
3. Does it reduce torque in any rev ranges (compared to standard manifolds)?
4. Would the manifolds give a good performance increase when used with an otherwise standard exhaust system and CAT? or does it really need a sports cat etc?

Dave

yes.

http://i16.photobucket.com/albums/b5...e/RollRd10.jpg

i cant say how much you would get on a std exhaust as i already had a decat and full system, but the gains are there to see.

Drew

So those gains were with the manifold replacement alone?

And what did the gains feel like when driving?
Very noticable?

Dave

Throw a decat with it and it sounds amazing, very noticable gains and transforms the sound of the car

But presumably then the car is not legal?
Don't you have to keep re-fitting a temporary cat for the MOT?

From what I seen, the JS manifold is well short of optimum. It makes more power than the original manifold. Not because the JS is particularly good, more the standard manifold is particularly bad.
The primaries are way to short for decent torque at the kind of RPMs the KV6 can muster.
The finish on the standard manifold is dire. Just look at this collector. The JS has to be be than the standard manifold.

That really is disappointing to see.
Looks like with some more effort they could have designed something way better.

But I guess in the absense of anything better, the JS manifold may still be worth considering, given that it's still a good gain over the standard one?

Dave

The only other way is making a good manifold your self.
The primaries want to match the ID of the exhaust ports and be as close to 30" long as possible before the collectors. The bends need be smooth and mandrel formed. The collectors need to be 1 over 2 and correctly welded so as not to impede gas flow. The secondaries need to be around 2" ID and be approximately half the length of the primaries. These then need to collect into a 2 1/2 free flowing system.
It's possible to build up a much better set of manifolds than the JS version.

If only I were able to make such a thing!

It's a shame there was never a performance replacement for the entire plenum (apart from the Sprintex supercharger plenum).
The normal plenum really doesn't look like it would flow well. And we all know how well designed and reliable the VIS system is don't we?

Theoretically, I expect with the exhaust manifold you described and an optimal plenum, the KV6 would have performed much better.

The result of a limited development budget for the zs, and the need to package it to fit in the front of the 45/zs.

very true, if you sorted the plenum and exhaust, dropped in some cams you should see 200lb/ft and around 220-230bhp.

With a decent set of manifolds and well designed exhaust system, the standard ZS180 would be a ZS195 or there abouts. Include a well flowing air filter housing and the std 2.5 V6 will make 200 bhp.
We don't really know how much is gained or lost by the plenum as not many have replaced them. I know of a couple of Rover 800 KV6 twin TB inlets. As to the power of those, I'm not sure.
Looking inside the plenum, it's a wonder the engine makes what it does.
It's almost like MG Rover built in HP restrictions. As to why, who knows, but I suspect it was to do with budgets.
Don't forget that in the right hands, the works 2 Liter KV6 made near 300 Bhp!!

Fred you sound like you know what you're talking about, why don't you make up a batch of these exhaust manifolds for the 180?!

I'll be the first to put my name down!:shifty:

I know of only one person who had custom mani's made (that were of a tuned length - forget haywood and scott) and they cost more than most people here would want to spend on a ZS!!! (although they are very good) Small quantities are still expensive until you get the numbers where its worth making a jig to produce them...unless you can find someone who would do it as a labour of love...???

Did Tony Law make some as well ?.

I was talking to a fella from Ipswich way on MGR forums a while ago and he was going to have a go at making some for the KV6, not sure whether he eventually got round to it.

My knowledge of what works and what doesn't comes from building some rather interesting engines back in the 80's. Then things were limited by head flow capacity.
With modern multi valve heads, it's the bolt on bits that limit power from the factory instead. The KV6 seems to be worse than other engine in this respect. It's almost like MR Rover were worried about warranty claims, deliberately down rating the engine.

I did loads of mods to my first ZS180 some time in 2003. I did use the JS manifold and custom made system to match. I was never happy with the manifolds though.
It wasn't until I did some number crunching that I realised that the primaries need to be long.
With the KV6, it's all about optimisation and knowing what does and doesn't work.

The problem with making up manifolds and systems now would be sales volume. There just isn't the demand for them to make it a viable proposition.
This would leave you, the owner to find an exhaust fabricator willing to make a 1 off.
The JS manifold will work for most owners needs and it is miles better then the factory manifold. But it's far from optimal.
This was discussed at length some years ago on XPF.
I don't have a ZS180 any more.
I do still run a KV6, sadly it's coupled to an auto box in a Freelander!!

The sales volume issue is a valid point, a while back I spoke with JS about making up some duel outlet systems for the 180, they would only make them in batches of 5, which I would have fronted the money for IF I thought there was any chance of selling the other four on, as it turned out I was pointed in the direction of a used system on ebay, so the JS idea never went anywhere.

Just thought I would see how much a mandrel bending machine would be thought I may as well give it a blast by myself and what better way to start to learn to weld.
Well I gave up at the mandrel bender part. £15k for a pneumatic one. Nearly £600 for a manual one.
Ha. I'll stick with my janspeeds.

Thankfully there are lots of ready formed bends available for the home constructor. These would need welding together to make pretty much whatever you need. ;)

As part of my maestro project I'm planning to do a night school course in welding, once the body's sorted I'm fancing knocking togeather a manifold............

Just a thought.

If anyone knows a firm that is capable of making some custom manifolds to meet Fred68's specifications, I was wondering, if we got enough people together willing to buy one, then a batch could be made which would get the unit cost down to something possibly affordable.

I don't know anyone, but even if there was, I guess they would need some time to design and develop it, plus also I guess the designer/manufacturer would need a loan ZS180 car to develop around and do trial fitments and testing etc.

I guess this idea is pie in the sky...

Manifold and exhaust design is extremely complex. In reality, to get optimum torque from any engine requires a custom designed system. A optimised manifold can help the cylinders fill with the next air charge. Now obviously anyone building systems for open market would need to compromise the system. Manifold primary and secondary length is dictated by many factors. The size of the pipes is very important. Too larger and gas speed will be slow. Too small and although gas speed will be high, back pressure will increase.
Primary length is dictated by many factors. Things like bore diameter and stroke, rod length and valve open/ overlap period are all important. To make things more complex. The optimum primary length is only beneficial at certain points in the rev range. The trick is to get benefits in key points in the rev range at the same time, not causing massive losses elsewhere in the rev range.
This is where secondary length helps. The secondaries can be optimised to lift low points in the rev range.
If all the science is removed from the design. The very best option is remove anything in the manifold and system that causes a restriction to gas flow.
This is why manifolds like the JS manifold work. It's not adding power to the engine, but it doesn't rob to much ether.

Years ago, I made several manifolds with slightly different primary lengths. The theory was to spread a smaller power increase over a wider rev range. It worked too but I found with this method, carburettor calibration almost impossible. Mostly because anything done to the exhaust is reflected in the intake.

Very interesting and a shame such a manifold was never developed.

Interesting reading, the fella I was talking to who was designing and building his own manifolds for the 180 was "2bellys" on .org forums. I'll give him a PM to see how he's getting on as it was around 8 months ago that he mentioned this.

The only way such a manifold would come to fruition would be if sold as a complete kit. This would come with heads, cams, ECU, air filter/cold intake and the manifolds and system. Going to this extreme would add lots of power over standard but the cost to many would be prohibitive.
As a DIY build, a well made manifold with longer primaries would be a viable alternative to the JS manifold.

'It's not adding power to the engine, but it doesn't rob to much ether.'

What you have just said is that the JS rob power?

a diy build mani would not come cheap, if you count up the bends in a custom set of mani's which have 24" primaries (and you are talking about 30" here!!!) on a kv6, and multiply that number by £15, which is the typical cost for a mandrel bent piece of steel, perhaps more for stainless??? you will easily exceed the cost of the janspeeds, this is before you've had the header plates laser cut and attempted welding it together!!!
To add to this, you will be ordering bends which are not off the shelf - as in, not a 15, 30, 45 degree bend etc.

Pretty much anything that is bolted to the exhaust or inlet ports of an engine will loose torque.
A correctly designed manifold will or can cause a vacuum in the exhaust port. This vacuum will draw extra air into the cylinder via inlet valve. This does add torque over and above that, that is generated by open ports.
This extraction only works for a set design of manifold. Any other type of compromised designed does in fact loose torque, when compared to open ports.
The JS manifold is much better in terms of flow over the standard manifold. This is why there is a torque gain.
It's not the last word in extraction manifolds for the KV6 though.

heres a very bad quality vid of the sound of my zs with janspeeds. http://s1363.photobucket.com/user/ia...250d5.mp4.html

all i have is a induction kit and janspeeds (not been remapped and is on standard cams) and its rolling roaded at 175bhp @ the wheels (190-210bhp at fly depending on how its guessed ;-) ), which is not a bad amount of power

Right ok, so I should have a net improvement over the MGR units with my JS manis?

I have an iTg, JS manis and cat back system twin exit, would love to know how much that makes. I did have a decat but she felt really flat with it so the cat went back on.

Definately

Id love to see what the full janspeed on ours has done

I saw a plot for iTg and cat back at 196Bhp, so I will guess at 205 with manifolds too.

Mine, with manifolds, sports cat and stainless catback has consistently made around 203bhp. What the manifolds seemed to add to on this car is the torque and I would need to pull out the last RR printout to see what it ended up at.:)

Sooo, not a bad guess then, There are 2 mods where I could feel the difference. The first was the iTg Maxogen, that really made a huge difference, they claim 12-14 gain and I fully believe that, the second was the manifolds but have no numbers for that. They say you cant feel anything less than 5% gain so with the iTg thats at least 9.6bhp. Total that and you are a hairs width away from 203.

Aye very close:) forgot to say it is a Bmc-CDA I have for induction:)

A good cold air feed is so important. The KV6 seems really sensitive to it. The number of 180's that I've seen with a small cone filter slapped onto the standard intake pipe is untrue. I wonder how the owners don't notice the lack of gain.
I did an experiment with my V6 Freelander last year.
The standard filter housing is dreadful as it sits on top of the engine. This causes it to warm the intake charge considerably, I've recorded 55°C!! I thought I'd try a large cone filter instead.
Not wanting to waste dyno time, I just rode my own dyno (the car).
I did a few 1/4 mile runs with both filters fitted.
The result was pretty much what I expected.
No difference between the two. Both filters give the same times.
I'm currently working on a nice cold are feed for my KV6 engine as they are proved to work well.

Years ago I stuck a K&N cone right onto the TB with Duck tape, took her out and was blown away with the noise, it was sweet. What caused me to subsequently rip the cone off was the total loss, yes loss of power. I was amazed after that to see people blowing hard about open cones in 180's, you really need to be brain dead not to notice the missing 40BHP with a cone. In-fact you deserve a cone if you like a cone.