k series exhaust query

[PAUL MARRIOTT]

My winter project is in final planning stage Jenvey TBs (Direct to head), Emerald ECU, polish up the head to help it breath but not gulp, Quorn 375 cams all of which will hopefully get me c.160bhp and a nice drivable car, oh + FOUR POT BRAKES ON THE FRONT TO MAKE IT STOP.

 

I'm having problems with the exhaust though. The car is registered July 2000 so I need to keep the Cat(?), Caterham only offer 4:1 with a competition silencer (no Cat!) I understand 4:2:1 is the way to go for the manifold but what pipe lengths? If I go for a repackable exhaust will I get onto trackdays? If I go for repackable and replace cat box for MoT when it arrives will I pass an emmisions test?........

 

Blimey, better stop with the questions now, seriously can anybody help or advise me to somebody who can?

 

 

[Delberts Wallet]

Paul,

 

I've just gone to 4:1 comp. exhaust. I had the same thoughts regarding the MOT. The only thing to do is to keep the old system in the garage and swap it before the test. Once done swap them back.

 

Thats my plan anyway.

 

Cheers

 

Gareth

 

Hmmm. How do you get you wife plus twins into a 7question.gif

[New Barbie]

My understanding is you need the cat for the SVA test but you will not need it for subsequent MOTs. There is a thread and I've kept the relevant MOT rules on my other machine but I recall the MOT test is visual only on emissions as for a pre 1975 car.

 

I'm not sure if there might be a difference if the car is built by Caterham or a self build - it would mean a difference in the initial registration of the car I think. I was certainly refused insurance as I am building my car myself not buying a car built by Caterham or an approved agent.

 

I'd guess you can get the replacement pipe to provide 4-2-1 with the -2- in place of the Cat.

 

[mike ashurst]

I had problems getting my '96 1.6k SS through the test as it failed emissions so I had to do loads of research, this is the (long complicated) story: -

 

Hi Folks,

 

I've just had the pleasure of my 1.6K Supersport failing it's MOT on the dreaded CAT test. (Full saga at V5's and MOT's)

Just in in case there's anyone who may be in a similar situation who doesn't know the answer and who missed the saga here's what you need to know:-

 

First of all, courtesy of Len Unwin(ex Caterham service manager):-

 

"Any Caterham built before July 98 needs only to comply with visible smoke

requirements as they are all deemed to be amateur builds. Even if the car

was fully built at the factory, before July 98 it was only ever supplied to

the customer still requiring work to qualify for amateur build status. That

is not to say that the car was not pushed from production to the service

area where the Service Department would finish the car. As you may imagine,

this is a bit of a "grey" area. As far as the MOT station is concerned, if

the car was built before July 98 it is amateur built. If customers had any

problems I always suggested (when I was service manager at Caterhams) that

they asked the MOT station to ring me at the factory. We would then explain

the situation. From memory, I believe it is section 6, sub-section 4 of the

MOT handbook."

 

Len's quite correct on the section numbers, I have now seen it myself, the only slight modification would be ti his first sentence which should read "Any Caterham built (from a Kit or set of Component kits)...."

 

The reference in the manual says something about cars that are amateur built (i.e. from kits or components as in 90% of Caterhams) should be treated as vehicles first used before 1975 and subjected only to a visible smoke test.

 

Lastly you need to be able to prove that your car was amateur built (In case your tester is a Jobsworth like mine). I got this Information from James Whiting, he's a really nice helpful bloke.

 

To do this you will need to look at the chassis number. The first 8 digits are the ones you need to look at, here are mine:-

 

SDKRDKCR - this is followed by a string of numbers

 

Of particular interest is digit 6 - in my case a K. This stands for kit built, it could be a C, for component built, or an F, for factory built. If its a K or a C then you are OK, you just need your tester to ring Caterham and ask them the question. James told me that around five years ago the Ministry issued some loose leaf directives which include info for the testers about Caterham chassis numbers which could be checked for proof, but he thought the easiest way to prove it would be to get them to ring the factory.

 

So that's it, thanks again to Len and James,

 

 

 

See the whole thread here : -

 

http://www.lotus7club.co.uk/blatchat/Topic.asp?topic_id=4532&forum_id=8&Topic_Title=Emissions+Tests+the+Definitive+Answer+%21%21&forum_title=TechTalk

 

Mike

[V7 SLR]

Exhausts By Design.

 

Great company who have engineered a solution I think beats all that I've seen Caterham sell. You get to keep your silencer, but they weld a collector onto the front, and make the longest primaries I've ever seen to go into that. They fit the lambda into the front of the silencer and your legal and free flowing.

 

I've not seen a better designed exhaust anywhere.

 

Email me if you want more info, or check out:

 

http://www.exhaustsbydesign.co.uk/

[Bob Corb]

Paul

 

Following on from our recent conversation at the last club night I would think that you could achieve 160BHP with the std exhaust quite easily. If you do want to achieve more mid range punch then 4-2-1 is the way to go. A long 4-1 will give you a boost at low speed and then at high speed, but it will stuff the mid range a bit dur to tuning effects. We could try to optimise a 4-2-1 for you using a combination of computer simulation, guess work and ultimately space available.

 

Caterham's best solution for you would be an SLR 4-2-1 with a 6" can. It looks a bit quirky having 3 Y collectors on the side of the car and the secondaries are too short too. A decent 4-2-1 manifold will be around 1 meter long but it all depends on detailed investigation. I'll see what I can come up with at work, don't hold your breath but as this is a winter project I'm sure we can come up with something special. I'd speak to the exhaust people detailed above there work looks pretty good, not the best , but not far off.

 

I won't be able to get to the next meeting as I'm doing my own Pilgrimage to Portmerion to christen the new car.

 

Cheers

 

Bob

[V7 SLR]

So Bob, who would you quote as being "the best" then? I've run across a few exhaust designer/manufacturers and have come away impressed by their work, but I don't actually understand the science of exhausts myself so I accept totally what they say as gospel. I can say that in comparison, those supplied by Caterham look of a lesser quality. The welds are rough, and the angles that the pipes are welded together seem very inconsistent.

 

I'm thinking of making a change.

 

Edited by - V7 SLR on 10 Sep 2001 16:29:12

[oilyhands]

In my experience the stock short manifold is a serious power sapper, in Mick Smiths case his old short 4-1 was 30ft/lb down at one point compared to the replacement 4-2-1, it was a similar story with Rob Days old short 4-1, it especially impacts the mid range output of the engine. The K seems *particularly* sensitive to exhaust configuration, especially as you up the anti in the cam stakes. The 1.8 seems to work best with 31 inch primaries of 1.5 inch diameter and 12 inch secondaries of 1.75 inch diamter. I'd say EBD would be a good bet to make you up a manifold with or without the cat, they made Peter Cs manifold and the one on my car.

 

Oily

[V7 SLR]

Whilst I've already got the 4-2-1 Caterham supplied exhaust, I fancy one with longer manifold pipes, and those that give more clearance to the starter motor. Rob Day's seems to be so intelligently designed I can't understand why mine wraps round so close to the starter. His manifold pipes are very much longer than mine too. I can't remember if his is a 4-1 or 4-2-1 though.

 

Also, he has the lambda in the front of the silencer. This seems more sensible to give an indication of what ALL 4 cylinders are doing rather than having just number 4 monitored as mine is currently.

 

I also fancy a carbon can at the end. I'm going for style points to match the hand brushed paint job on the Gravel-Rash side. smile.gif

[oilyhands]

Rob's is a 4-2-1, but the secondaries are quite short.. the only problem with such a remore Lambda position is the time it takes to get up to temperature and keeping it up to temperature. With the M3DKs closed loop currently disabled on Robs car it wont actually hurt, it's only useful for mapping.

 

Oily

[PAUL MARRIOTT]

Gents, many thanks for your responses which have confirmed my understanding and advice to date, I'll go for the 4-2-1 and have sourced a firm to make one up for me (more about them when I've got it.) I'll leave the lanber in no.4 pipe, simply because I want the exhaust to look clean and I don't want it wacked by stones when I take my next excursion off track.

 

Bob give me a call 07768 005701 and I'll give you details off our next run and a good route back from Portmerion.

 

K7 PDM