Exploding plenum

[brett84]

Not the best start to a Sunday.
Tried to start, instantly made a loud bang and bits of the plenum got fired out of the bonnet vents.
It's gone with so much force it's ripped the bonnet support off as well.
Double f&&k!!

What to do now?
Do you think it could be repaired? I might contact Tim at ACT tomorrow but I didn't buy it from them directly?
But then it might do it again.
I remember now when Shaun mapped it he said to always give a bit of throttle when starting because he's seen a few carbon plenums explode with a backfire


I really want this plenum as it's running a 76mm throttle body and i don't think the standard can be taken out that far can it? I suppose I could TIG weld the 76mm jag throttle body onto the standard plenum but that might not work either?

Edited by brett84 on Sunday 19th April 20:04

[TV8]

I am sure that that isnt right and at least there is no other damage. I would have a word with Tim.

On another point, have you done away with the plug extenders and put some form of sock around the plug leads?

[brett84]

it's so frustrating as i've now got to repair the bonnet as well.

Yeah I made some plug leads with an angled boot and then used lead protector boots for insulation but to be fair the leads are really tough anyway, but they don't do any harm. The leads some semi-finished you just cut to length and add on the coil pack connectors, dead simple with the tools you get from there, just clamp on. They were Moroso blue max 8mm, really beefy things
http://www.realsteel.co.uk/section9.pdf

[phazed]

I have heard of your problem, (through Shaun I belive) but never experienced it myself.

Did Shaun set yours up?

Maybe something's not right?

[brett84]

yeah Shaun set it up and the engine runs fine normally.
I just tried to start it this morning without touching the throttle and this happened as soon as it tried to turn over. Bloody loud bang it was. Normally starts fine, bit rich until warm as there isn't a stepper or idle valve.


I'm wondering what difference in the real world the 76mm TB makes over standard and if its worth messing around or just go back to the standard plenum and open it up as much as possible?

[ChilliWhizz]

Sorry to see that Brett, and no consolation but a couple of years ago at Kerridges I saw a Noble with an exploded plenum, same thing, humungous backfire had blown the thing apart....

[SILICONEKID345HP]

brett84 said:

it's so frustrating as i've now got to repair the bonnet as well.

Yeah I made some plug leads with an angled boot and then used lead protector boots for insulation but to be fair the leads are really tough anyway, but they don't do any harm. The leads some semi-finished you just cut to length and add on the coil pack connectors, dead simple with the tools you get from there, just clamp on. They were Moroso blue max 8mm, really beefy things
http://www.realsteel.co.uk/section9.pdf

Show them you rebuild and mod blog .

They keep telling us carbon fibre is stronger than steal .. They make prop shafts out of the stuff .

Edited by SILICONEKID345HP on Sunday 19th April 19:41

[brett84]

It will be alright to drive like this won't it? It's about 2 miles to my nans house where the garage and all the tools are.

I need to make a proper blog when I get a spare evening, put everything together, might be able to help some people out who are working on their own

[Pupp]

That's rotten luck, almost a case for a sacrificial panel bonded onto carbon plenums. I'd want to keep it so hope Tim can sort a way.

[phazed]

CF wouldn't stand up to an explosion like thick cast ally. It has other strengths.

Mine has never backfired, no idle control valve or stepper on mine either.

[brett84]

What would cause a backfire do you think?
I was running fine really, Shaun mentioned he was surprised at how steady the idle was. A bit lumpy on startup until warm but never had any problems firing up, normally straight away

[Pupp]

brett84 said:

It will be alright to drive like this won't it? It's about 2 miles to my nans house where the garage and all the tools are.

I need to make a proper blog when I get a spare evening, put everything together, might be able to help some people out who are working on their own

You'll not be able to drive it, the hole is letting in un-throttled air.

[brett84]

agh st bags, didn't think about that, I was thinking about cars that run without air filters but thats still going through the throttle

[jojackson4]

Piece of plastic and some shrink rap may get you there that's if you can get it air tight

[SILICONEKID345HP]

brett84 said:

agh st bags, didn't think about that, I was thinking about cars that run without air filters but thats still going through the throttle

What about gaffer tape to get you home .

[brett84]

I'll have a look tomorrow I was thinking I might be able to tape the piece back on thats been blown off if it's a clean break. Tape it up airtight at least. I'll find a way

[peaktorque]

Shocking.

For what they cost, I'll be sticking with the standard piece.

[chris watton]

Wow, sorry to see that. They're not cheap, I would expect it to last the lifetime of the car/engine!

[phazed]

How often does an engine backfire through the inlet.

I've had my car with a CF plenum for a cople of years and never a backfire.

I suggest something isn't right.

FYI, I never use throttle when cranking, just a tiny dab as it fires.

[EGB]

Perhaps, don't inadvertently blip the throttle when switching off the ignition. There could be some unburnt fuel in the manifolds when restarting, and boom?