Plenum spacer... worth it or not and what material??

[TVR Beaver]

Made this the other day our of Whale Brand Tuffnoll.. got it on the CNC and it fit's very well... it's 10mm thick and will stop 90% of the heat getting into the top and increase the volume a bit... what's the thoughts on these things... worth fitting??... and what materials usualy used?... you can shatter tuffnol but it's hard to do... but if it was to go.. the bits going down the trumpet would cause some serious damage?... did think about siliconing the inside edge of the spacer so if it did shatter.. it would be held by the silicon and not inducted in.... but then will the silicon come off?? [/url]

Any thoughts??

[url]|http://thumbsnap.com/v/MrtMWPJ7.jpg

[GreenV8S]

Phenolic sheet is ideal (that's what Tuffnol is) because it has the same coefficient of thermal expansion as aluminium. There's no reason for bits to break off it. I wouldn't bother with silicon, but if you do and if you have lambda sensors then make sure you don't damage the sensors.

[Pupp]

Looks spot on. I'd use it with no hesitation in that material but if the CNC progamme has been preserved, then nylon chopping boards work well too apparently

[TVR Beaver]

Yes... was going to make 1 in Nylon 66 also... I have the prog so could try later.. Just need to establish the system basics for when MA set's it up.. no point setting it up with one on and then taking it off later... it will change what MA does.... I've had it clamped up over night and it's showing no pressure points so happy with that.. Did read on a post that it made throtle responce slower when fitted?... and I've also misunderstood the insulator bit... that appears to be insulating the trumpet base from the manifould and not the base from the Plenum.... Infact it is suggested that heat transfer into the Plenum top acts as a heat sink for the trumpet base keeping it cooler????? so doing this may be detrimental to heat build up in the base??... Who knows...
I've got two test pieces in petrol and oil now for 2 weeks whilst I'm working away... I'll see if there is any adverse effects... Will bolt it back on a go for a spin... but changed that much now I don't what's caused what if it's better or not!...

[Boosted LS1]

While you're at it have you thought of a resin liner for the inside of the plenum? I don't know if any of these things produce noticeable gains but they can't hurt if done well.

[TVR Beaver]

Peter... What does Silicon do to the Lambders???... I've sealed the top on now with silicone and left the infeed pipe off and butterfly open till it cures?... It says oxygen compatable and it's from the USA so sure it will be okay... but just interested to know what 'normal' silicone does?... and does it do it only when curring... or afterwards also??

[GreenV8S]

Insulating the trumpet base from the manifold is the best way to reduce heat soak, but spacing the plenum top up is suggested as improving the air flow inside the plenum and if you're fitting a spacer in my view it makes sense to insulate there too.

[Boosted LS1]

^ Once it's been sucked through the engine intake it gets expelled via the exhaust valve into the .....

[TVR Beaver]

May be it's somthing given off by the stuff whilst curing that gives them problems... it sure makes my eyes water if you get too close!!... thats why I left the butterfly open for a few hours whilst it went off... but as you say... how does it get thru?.. there may be 1 cylinder with the exhaust and inlet slightly open... but why would it want to flow toward them??... anyways.. all fitted and working now.. with the red tops... spacer..K and N.. Vac takeoff moved forward... MA chip (provisional setting) and the stealth cam... it appears to be more like it was before I started now so pleased with that...
I still have the new Bosch MAF meter to fit... and try improve on the corrigated hose on the induction... them MA can do his bit... so looking good... but a lot of time, effort and cost to get back to where I was... just shows how good some std 500's can be... 280 at the Growl.. only mod.. pre-cat's out... wondering what I'll get when MA does the biz and I upgrade the other parts!!!

[Pupp]

If it assists, the commercially available ones are a gnat's cock over 15mm thick.

[GreenV8S]

Quinny said:

GreenV8S said:

I wouldn't bother with silicon, but if you do and if you have lambda sensors then make sure you don't damage the sensors.

Not sure how silicon on the plenumn is going to get anywhere near the Lambdas????

As I understand it, some silicon sealant releases acetic acid as it cures which is bad for lambda sensors. You can get stuff that is 'lambda sensor friendly', or wait for it to cure fully and make sure it's been well ventilated before you start the engine.

[davvid]

Mark Adams reckons smooth bore trunking releases 5-15lb/ft of torque,presumably the higher figure on a 5 litre at higher revs,its hard to imagine a spacer would effect things that much,so unless somebody knows differently,I wonder wether its worth doing?

[Boosted LS1]

Quinny said:

Boosted LS1 said:

^ Once it's been sucked through the engine intake it gets expelled via the exhaust valve into the .....

Really...??? Have to say I know the route, but I think the chances of it actually happening are a bit on the slim side

I agree but they do seem to make plenty of warnings about this as well as making lambda friendly silicon. You've only got to see how debri from one cylinder can find it's way into another when things go tits up to appreciate that pliable soft silicon could also travel through an engine.

I had a friend who lost a carbon fibre trumpet from his intake. It was in his plenum and he never did find it. It passed right through the engine and probably got burnt up in the process.

[Pupp]

Boosted LS1 said:

Quinny said:

Boosted LS1 said:

^ Once it's been sucked through the engine intake it gets expelled via the exhaust valve into the .....

Really...??? Have to say I know the route, but I think the chances of it actually happening are a bit on the slim side

I agree but they do seem to make plenty of warnings about this as well as making lambda friendly silicon. You've only got to see how debri from one cylinder can find it's way into another when things go tits up to appreciate that pliable soft silicon could also travel through an engine.

I had a friend who lost a carbon fibre trumpet from his intake. It was in his plenum and he never did find it. It passed right through the engine and probably got burnt up in the process.

For some strange reason that just made me grin... I quite like the idea of following traffic being peppered with spat out carbon confetti

[spend]

Stop effin around and ask the expert!!!

I'm sure Daz will only be to pleeesed to give you the benefit of is wissdom

Are we all on the same song sheet BTW, OP was asking about coating the inner surface (not the mating surfaces) with silicone. I could foresee that ending up in the engine if it peeled off?

[GreenV8S]

Pupp said:

For some strange reason that just made me grin... I quite like the idea of following traffic being peppered with spat out carbon confetti

I still had a cat fitted during some of the early trials with the supercharger, and with one thing and another it got so hot at one point that it literally melted. Most of the matrix was left in a molten puddle in the bottom of the Y piece but quite a bit was blown out of the tail pipe and left holes in the plastic front bumper of a car parked twenty feet away.

[TVR Beaver]

davvid said:

Mark Adams reckons smooth bore trunking releases 5-15lb/ft of torque,presumably the higher figure on a 5 litre at higher revs,its hard to imagine a spacer would effect things that much,so unless somebody knows differently,I wonder wether its worth doing?

Did try a ACT one piece hose.. but could not get it in... my rad top inlet spigot is quite high and it was causing problems where the hose goes down and under the bonnet... near closing up flat so sent it back... I'll need to use some cori in this area but will make the rest 3" smooth bore... not ideal I know but may give some advantages??
One thing I did find when fitting the K&N was the outlet from the air filter cover was quite a rerstriction due to a lot of material (fibreglass) being used in the manufacture.. it measeured 60mm ID in one place (the ID was not round... I've spent some time on this now and the ID is round at about 68mm... but for sure, this is the smallest dia in the system... but it does not always follow that this is the biggest restriction... think eddy currents from the cori makes for a bigger issue... but what do you get if you have 68mm box hole, 90 deg smooth bore, 2 bends in cori and the run up to the MAF in smooth bore?... could be a mess and full of pressure waves.... Will take both options when setting up so we can test the diff they make....

[Simon Says]

Quinny said:

GreenV8S said:

I wouldn't bother with silicon, but if you do and if you have lambda sensors then make sure you don't damage the sensors.

Not sure how silicon on the plenumn is going to get anywhere near the Lambdas????

The vapours of the curing product is what does the damage to Lambda probes(well if its run while its curing)i use Wurth RTV in the workshop with no vapours while curing,well anywhere near the intake anyways

[macdeb]

I fitted one, tried it, engine bogged down a little when 'floored'. Took it off, no problem so it didn't work for me. Anyhow, isn't the increased volume the wrong side of the throttle/butterfly?

[Simon Says]

macdeb said:

I fitted one, tried it, engine bogged down a little when 'floored'. Took it off, no problem so it didn't work for me. Anyhow, isn't the increased volume the wrong side of the throttle/butterfly?

Strange i have the SC insulator and spacer fitted,motors def more responsive after 3.5k but that's possibly down to the unshrouding of the trumpets than just the increased volume and cooler plenum or a combination of all three i done this mod without changing anything else.

Edited by Simon Says on Tuesday 13th October 22:05