Exhausts And Manifolds

[DeanB]

I am thinking of investing in the above.

I want:

Better sound (but not too loud)

A little more power

A big weight saving (right at the back of the car where it could use it the most)

 

Anybody got any advice? I have read that you can save 16 kilos from the back box alone, but getting accurate info on how much weight can be saved from a stainless 4-2-1 manifold is tricky. And do 4-2-1 manifolds make much difference on standard or nearly standard engines?

I quite like the look of the Hangar 111 back box. Does any one have any experience of it?

 

Any thoughts will be greatly appreciated.

 

Ta

 

Dean

[Martin R]

Dean, a 4-2-1 with no head porting mods will give you only a small gain for a quite large amount of outlay. If it were me i would go, in this order

 

Head porting, usually after HGF

Cams

4-2-1

 

You can also get small gains from induction exhaust.

 

Regarding the exhaust backbox, if you intend to do the odd trackday you want a reasonably quite one. You will not get on places like Bedford otherwise. Im going to go for a 8 inch EP one personally. Although i do have the car decatted which increases to noise quite a bit.

[fentuz]

I agree with Martin.

 

In the view off upgrading slowly towards a 160, I fitted a janspeed 421 because my down pipe wasn't the best and lamba etc.

I can't say I was impressed; many people say it gives more power/torque etc... Well I think it is a placebo effect. As I said before, a close ratio gearbox made much more changes than the exhaust line ( for a lesser cost). Talking with Dave Andrews, the EP manifold is supposed to be better for our cars.

I needed a cambelt job and got the camshaft reviewed... And again, I am not impressed that much (compare to the investment) but I have to say that it made a difference on track since I can now keep up with 111R. Being in 120 was getting too low and I had to spend most of time leaving slower corning car overtaking or trying to overtake unsuccesfully... But the camshaft and manifold seem to give that little plus.

 

160 is the way forwards, anything between the std 120 and VVC is not making a great deal of difference... Or might give greater placebo effect than power effect.

 

Oups, I forgot to mention that I got my janspeed tail pipe from twin exit to a single exit. Thanks to this, I can fit a super tap to get throught quiet trackday... Bedford, Goodwood, Combe...

 

Supertrap sometime manages 100 to 97 db reduction

[stockhome]

Hi Dean I have a janspeed 4-2-1 and eliseparts silenced decat at hanger 111 signature exhaust and I like it. But I would say that.

 

It made a bit of difference But mine is a 135 engine which has a bit of handwork as standard

[DeanB]

Thanks guys. I am thinking of having the head ported at the same time....

 

Is there much of a weight saving with the manifold does anyone know?

 

Stockholme what inlet manifold does yours have on the 135 engine? Its an ally one isn't it? Can you get hold of them?

[fentuz]

what inlet manifold does yours have on the 135 engine? Its an ally one isn't it? Can you get hold of them?

 

The vvc manifold is easy to get on ebay, I got one somewhere. But from what I understood from head porting people, it doesn't make much difference for 160 cars and since it's aluminium, it argubly heats up the inducted air reducing combustion yield.

 

Have a chat with dave andrews, from what he said to me, you book the car in, you go there, take off the current head and replace it with a reworked one with predefined camshaft. It's like change a head gasket procedure. And you leave in a much more powerful car

[DeanB]

I will have a chat with Mr DVA

[Martin R]

I doubt the inlet manifold will make much difference. In fact if it is not matched to the inlet ports on the head it may well make it worse.

To optimise perfomance the inlet and exhaust ports both need matching to the inlet / exhaust manifolds.

[DeanB]

I have spent an enjoyable hour or so researching these things on line. Needless to say the wife thinks I am insane.....

 

Anyway, I am liking what I have read about Sabre heads (Kiwirog?) and 2bular exhausts.

 

From you guys comments a 4-2-1 seems unlikely to improve performance on a mildly tuned motor (especially when compared to a modified to match standard one) so it doesnt really seem worth it unless there is a big weight saving to be had. I still can't find what the weights are though. Maybe Mr Fish will be along soon with his insight - I know he has just fitted a 4-2-1 to his.

[Martin R]

Kiwirog does some very nice work. He appears to get very good gains from porting and having 2 different sized inlet valves to improve turbulance and output apparently.

 

Dean if you have the money buy a good second hand head. Get kiwi to sort it and then its a straight swop when you are ready without having to have the car off the road for long. You need to look into how far you can go on a standard ECU before needing an Emerald.

 

Should be about 155 ish ?

[DeanB]

155 would be plenty! 35 more than I have now, with good torque across the board aswell. I am slightly sceptical of some of the numbers mentioned on his site tbh - he seems genuine, but you never know how accurate rolling roads are do you?

[Martin R]

Dean, dont be sceptical. IIRC Rog worked for PTP for a number of years. He ported a great many K series heads. His work really is top notch by all accounts. You will get no better than Rog or Dave. Rog normally has a lot shorter waiting list though apparently.

[John FISH Curtis]

Dean,

 

I have replied to your message and agree with the above comments.

 

Mine is 135bhp at the moment, I need to take you for that spin in it.

 

My next step is to get Rog or DVA to do some work on my head, my only concern, with the current mods i'll be getting 150-160bhp and i think the bottom end/pistons wont take it.

[DeanB]

John I will hold you to that spin!

 

From what I have read, the bottom end is fine to past 160bhp except for the pistons. The 160 trophy pistons are ok and obviously forged ones are up to the job. If I was you I would buy a set of 160 pistons and have them balanced and then fitted when you have the head work done. But I am very far from being an expert - you would be far better off listening to what someone who knows what he is talking about (Martin R for instance) says.

 

It's all good fun though.

[Martin R]

The 160 pistons are stronger as they have a slightly bigger ring land at the top. This is where the ordinary pistons normally let go. However my old S1 111s had the VVC head ported by DVA. It nust have been making at least 170 - 175. I sold it to Matt C. He then sold it on to someone who raced it in the Elise trophy.

 

It never failed AFAIK. I would fit 160 pistons if doing a rebuild. I would however have no problem running a car with a ported head and ordinary pistons up to 160. After all AFAIK S1 Sport 160's had ordinary pistons IIRC. Most of these made very close to 160.