Plenum chamber query

[Dannyboy]

I shall outline the issues first...

My old shed runs the original metal Supersport Plenum... The lower aluminium cast manifold has cracked and shear at the fixing lugs - I think this is likely to have caused what appears to be a HG failure by allowing water to exit the casting in the end of the head past the gasket and into cylinder 4...

The casting looks like it's scrap - the rear stay was missing and they are no longer available which I think over time is what's caused the shear failure through vibration and unspoorted weight.

So, I have found an old Metro GTI inlet manifold and plenum as these were likely to have been the ones used in period.. except - it's not. The supersport inlet manifold is longer and the spacing between ports where the plenum bolts to the manifold doesn't match at all..  Looking through Rimmer bros - I'd guess Caterham either had the inlet manifold manufactured or used something I can't find a match for.

Later plenums and cars use a different throttle body - mine is the old style with stepper motor control - I now have a spare for this rare item as the metro one came with a TB (Malcolm - I know you've also had trouble locating one of these so I will carry a spare as well as the metalastic fixing to the plenum!

So, I've looked at VVC plenum chambers - but these are prohibited under the regs from what I've seen for 2016. Anyone have any ideas of what the original supersport manifold was from to replace this and retain the exsitng plenum? or... would i be permitted to replace the entire mainfold for a vvc or equivalent? I know from comparing that I'd have to block some of the sensors that the later cars and TB's used due to the antiquated age of my car..

Suggestions welcomed.. other than fit throttle bodies and move up a class I quite like the old shed as it is, more power would be fun but I'd rather replace the chassis given it's age and mileage.

[david nelson]

Dan

welcome to the madness of class 2 and 3 . Should get a sigma engine and use any induction you like TB or plenum.

well back to topic

i understood the 1.4 supersport plenum as specific to Caterham and a now very difficult to find. Under the 2016 regs your seven is now obsolete for class 2and 3. Sorry to give you this bad news. Even with less power than the more modern sevens but we need to accept democracy as the was a vote and that's that.

 

if I was comp sec and I am not a pragmatic way would be to buy a standard plenum and put a 52 MM TB on it. Going to a VVC plenum would upset people.IIRC it did not make any difference to car retro fitted with them to either bhp or torque.

just remember old cars with no spares and less power are have to rely on finding parts and driver talent, modern sevens can have programmable ecu, and any given induction.

ps if you do fit a sigma then I am sure someone will say it not the original engine for your car and throw their toys out of the pram. 

[Mark Durrant]

Dan

I believe the X-Power K Series have an ally plenum so fit one of these as it complies with the regs.

Mark

[Dannyboy]

David...

I'm NOT going sigma or changing the car or engine... Should I ever sell the car it's to buy a Sigmax or Sigma race car and head back  to the circuits..

If the alloy x power plenum - which resembles the VVC plenum in dimensions etc (I recall these were the plenum fitted to Mega Grad cars) is legal then I can engineer this to work..

Or - I fit the metro GTI inlet I've got - but I'm not sure that was ever fitted to a caterham..

[david nelson]

Dan 

 

Mark is correct. Vvc plenum allowed for 1.8 but not 1.6 if you read it that way. It also say via standard plenum so it could read it's not allowed, as it's not standard to you model . 

Chris, could you as comp sec clarify this please. As it is unclear 

thanks

 

David

[Mark Durrant]

The regs state 'Rover K series 1800cc engines provided induction is via the standard production plenum'. As Danny's engine is a 1.8 and an X Power plenum is a 'standard production plenum' iif fitted it will comply with the regulations.

Mark

[david nelson]

Mark

interesting . My standard 1.8ss was produced with a plastic plenum. This was the standard plenum for my engine spec. Despite this I am able to put a non standard plenum on my car. 

Go one stage further is this standard for Caterhams or all k series as these too would by your definition be standard production plenums for this engine?

david

[Mark Durrant]

David

The point of the regulation is to stop a competitor going to the expense of developing and manufacturing a plenum that will provide a performance gain. I would also point out that the published power output for a Supersport engine did not change depending on what plenum was fitted and I personally would expect to see little difference between the two. I suggest Dan obtains confirmation from Chris that my interpretation is correct so he can compete next year.

Mark

[Richard Price]

Dan,

If you use the ally Xpower plenum, it will foul the bonnet unless you use the VVC/Xpower RHS engine mount to lower the engine. (both Jeff and Tom have bonnets badly worn through the louvres...) 

If you can make a plastic plenum work, and its deemed allowable, then that may be the better way to go.

I think it is very questionable whether either Xpower or VVC ally plenum actually offers any gain over the plastic one.  

[Dannyboy]

Richard

Thanks... I've already shaved the RHS engine mount to stop the existing plenum rubbing through and would do the same for whatever plenum I can find to replace mine. I'd fit the plastic one but would have to re-engineer it to blank off some of the sensor holes...... hence someone may then call into question it's eligibility.

I'm not really fussed about a slight gain or loss of performance - I'd get more gain from losing 25kg or so and actually setting the car up, along with new tyres and having the diff refreshed than I will ever gain from a couple of BHP from the engine.

[Comp Sec]

Dan YHM

[Comp Sec]

Gent's

following discussions with Dan I can confirm that Marks interpretation is correct and advise  the following specifics :-

Providing that the plenum is a standard caterham Plenum for a 1.8 k series a later plenum of the same or different material may be used and where necessary sensor points adapted or blanked to match the original installed plenum sensor requirements.

What can't be used is a plenum from either a different engine size / type, an otherwise modified plenum or one from a non caterham.

If you have specific queries relevant to your indivdual circumstances please feel free to contact me.

[david nelson]

Chris

 

thank you for the clarification. I thought it was as Mark had written but there was some room for confusion due to the way it was written. 

 

David

[Englishmaninwales]

Chris

"What can't be used is a plenum from either a different engine size / type, an otherwise modified plenum or one from a non caterham"

This implies that the larger plenum and 56mmTB as fitted to the early 1400 k Supersport that Dan refers, cannot be fitted to a 1600/1800k.....this is the arrangement I have used for the last 11 years. This has been discussed previously (I think when Mark was CS) and considered allowable as there is marginal/nil performance gain  and is a significant weight penalty over the standard plastic plenum.

Malcolm

Edited to add: there are significant difficulties with respect to the ECU, stepper motor idle control and engine loom to be overcome to fit the standard later plastic or metal plenum / TBs to early re-engined K series cars.

[Comp Sec]

Malcolm,

I've no knowledge of previous discussions if you can point me to the relevant BC post or if Mark can confirm that is correct, then I will take that into consideration.

[punch]

HEY RESULT!! 

Can i have Malcolms  points from the last three years cos he's always beating me?

   

Philip.

[david nelson]

Malcolm's plenum has been signed off many years ago. I remember the discussion at the time . It would have been silly to have made him buy a new plenum . I guess it's the only bit left from his 1.4k?

 

[Englishmaninwales]

Chris

I don't think it was ever discussed on BC. There have only ever been two competitors (myself and Dan) who used this arrangement (and for several years only me as Dan went off racing).

I raised the issue with Mark at the time and the opinion was as above.

Malcolm

[Mark Durrant]

Chris

I can confirm Malcolm is correct and given the weight penalty (including the driver ) I saw no reason for this not to be permitted.

Mark

[TomB]

Ive still got my original 1.4 SS induction in the loft.  Forward facing TB, alloy manifold, black powdered coated plenum.  Ive been running KV6/ SLR throttle bodies for a few years now and have binned the original seized 1.4 block.  

Will swop for a Dry Sump pan ;-) 

 

 

[Comp Sec]

Mark,

For clarity does that mean that any Caterham Standard k series plenum can be used on any K Series regardless of engine size.

[Englishmaninwales]

Tom

Dan might be interested in your plenum and inlet tract casting (see above) -  the 2 supports also, as the inlet tract casting cracks, as he has found, without them. Been there done that one.

Mark

Ive been on a diet.....

Phillip

There isn't a two finger emoticon. Tough luck, you just need to be faster.

Malcolm

[Comp Sec]

Gent's

In order to close this thread following the various discussions, and no negative replies to the comments please find attached the following amended clarrification :-

Providing that the plenum is a standard caterham Plenum for a k series, a later plenum of the same or different material may be used and where necessary sensor points adapted or blanked to match the original installed plenum sensor requirements.

What can't be used is a plenum from either a different engine type, an otherwise modified plenum or one from a non caterham.

If you have specific queries relevant to your individual circumstances please feel free to contact me.