Hehe, silly me. Wot, you mean a Felicia isn't a 600 sportsbike? Oops

Indeed, at least where the intake currently is should be subject to some actual aerodynamic pressure, rather than just trying to divert a low-pressure slower-moving boundary layer like a bonnet scoop would. Correct me if I'm wrong, but the point I was trying to reinforce in a roundabout way is that the ~40mm intake pipe was originally feeding a 35-40mm throttle body (I forget exactly what size the 1.3 has), so unless you enlarge the whole inlet path to at least 65mm there's no possible way to not use power from the engine to suck the air through it without forced induction. I am thinking in terms of minimising potential losses rather than magicking extra power out of nowhere, although I'd be happy to cook you up some sprout chilli in the name of experimentation, Jim.

forgot to mention this, i contacted piper cams, and they say they can re-profile the standard cams with a re-grind for approx £270, which doesn't seem too bad imho.. something to think about methinks.. suppose i ought to get onto porting up my spare cylinder head too when the weather is a bit warmer :wonder:

are there not any vw racing cams kicking around anywhere mate, maybe german ebay or such like, not a fan of reprofiled cams with bucket followers they put a bit too much side load on the buckets for my liking. whats the cam like from the vvt head as they make 125bhp std

oh Tom are you still running the std steady bracket under the gearbox?

I modded mine by the luck after finding that the big bush was the same size as the fabia rear wishbone bushes we fit (we fit the audi solid ones) it needed a skim in the lathe a tiny bit and pressed in tidy its even the correct width, I had a length of 17mm hex bar too which is a good fit inside the bush (altho i think a round bar would be fine also) you really would not believe the differance in gearchanges and hardly any extra cabin noise (makes the whine in 1st a bit louder is all)

as usual i'm far to useless to take pics at the time lol so i'll try and find some

there are 3 different size rear mounts and i'm not sure which one i used now but think it was a 1.6 or diesel one :wonder:

sneaky edit

this is the bush we fit in the fabias (but not at that price)

http://www.jabbasport.com/store/index.php?app=gbu0&ns=prodshow&ref=6LL407183

and this is the mount I mean

http://www.jorily.com/catalog/index.php?main_page=product_info&cPath=131_4_36&products_id=911

Edited 3 January, 201115 yr by felicia16v

interesting stuff that jimbo, i'm still using the bog-standard mounting as supplied by jorily.. the other thing that is quite useful is that powerflex now make an updated version of thier 'udder' bush which is pretty much a solid polyurethane bushing... nice piece of hex bar wit a hole drill through would be ideal for that..

which part of it needed to be skimmed down in the lathe?

edit: none of the later roller-rocker cams will fit the early cylinder heads sadly, new cams are available from schrick or newman etc but they are upwards of £600 for a set made from new virgin blanks, so it seems a re-grind is the cheapest option, i don't like them either

Edited 4 January, 201115 yr by TeflonTom

I had to turn the bush down slightly to fit, only about .5mm or so of the alloy around it.. under no circumstances do not cut the alloy with a hacksaw thinking it will allow it to close up when pressed in, as it springs open a thurther 5mm then and makes it impossible to fit 2nd attempt was to turn it slightly in me lathe lol.

made a massive differance to the gearchange and putting power down with less tramp

I need me one of those! How much for the bush, pre-modded, Jim?

i'll sort you one mate I already owe ya one. do you want me to find the bracket too? pretty sure its a 1.6 one thats needed

thanks for the heads up on that jimbo, i'll order a bush in and have a play wit it... the other type i looked at was using a rubber from a citroen for the left hand gearbox mount which is solid too.. i can find it at the moment though

nooo under any circumstances never ever fit a part from a citreon... ever you understand me........................

i'll sort you one mate I already owe ya one. do you want me to find the bracket too? pretty sure its a 1.6 one thats needed

That'd be grand... I know the one on the rally car was the reason we had so much noise, it's knackered, so I may as well uprate it when replacing!

I think this is the "factory" version (as used on the old Skoda Challenge Felicias) and still available from Czech...

Clicky

Cheers

James

I think this is the "factory" version (as used on the old Skoda Challenge Felicias) and still available from Czech...

Clicky

Cheers

James

do you know if there's a skoda part number for that part?

do you know if there's a skoda part number for that part?

There is, or rather was.

I've got a Skoda Motorsport catalogue from 1997 with a collection of parts listed for the Group N Trophy Felicias.

The bottom gearbox bush was MS230041N, but I'd be astonished if you can still get them from the factory.

I've bought stuff from Speedpro in Czech before - paid by bank transfer, and all was well. I think their price for that item works out at around £10, not including P&P. (It was £4.73 from Skoda Motorsport UK in 1997!)

They also do the solid mount for the Felicia Water Pump and the rear mount of the Front Wishbones.

Cheers

James

FInished your car yet James?

Not quite, but it's getting there. Just a taster to avoid taking Tom's thread totally OT...

^^ dammit i want some of those arch trims similar to those for my pickup, and some skirts off a fun too.. my pickup is in the paint shop at the moment so i can't fiddle with some of the bits i've been collecting

On the "ram air" thing", I think it's mostly advocated by people who genuinely don't realise just how much air an engine swallows per minute.

I would reckon that a non-turbo road engine needs about 50 cubic feet of air per minute (CFM) for each litre of engine capacity. Flowing this through a 3" dia (~0.05 square feet) pipe gives us an air speed in the pipe of about 500 feet per second, so true ram air (like an F1 intake) at road speed might increase air at the plenum by about 10%. 10% more air at the plenum will be worth about 1% more power at the flywheel!

On the "ram air" thing", I think it's mostly advocated by people who genuinely don't realise just how much air an engine swallows per minute.

I would reckon that a non-turbo road engine needs about 50 cubic feet of air per minute (CFM) for each litre of engine capacity. Flowing this through a 3" dia (~0.05 square feet) pipe gives us an air speed in the pipe of about 500 feet per second, so true ram air (like an F1 intake) at road speed might increase air at the plenum by about 10%. 10% more air at the plenum will be worth about 1% more power at the flywheel!

Why reckon? Surely by definition an N/A engine won't draw more air than 1 cylinder volume per inlet stroke? (as a theoretical maximum, ignoring inertia and scavenging effects) The figures I gave when I mentioned it were based on 800cc per crank revolution (1600 engine, 4 inlet strokes per 2 revs) giving the ~120mph air velocity up the standard ~40mm dia. inlet pipe. Now realistically that 5000rpm is going to be hit in 4th gear or below, so that air will be entering at (assuming a perfect intake and ignoring wind) ~50mph or less, thus something must provide the power to accelerate that air to nearly 3 times as fast as it was moving, and that can only be the engine. I cheekily mentioned ram-air to emphasise the opposite point

Sorry I caused the confusion by bringing up misleading terminology - I've picked up a fair bit from bikes rather than cars, where you're considering an intake of much larger size relative to frontal area, located near the point of highest aerodynamic pressure. 'Ram-air' was good for ~5bhp when Honda redesigned the (100bhp) CBR600 in the mid '90s, and for the '03 ZX-6R Kawasaki went as far as a very complex frame design in order to run a straight intake through the headstock, so it must be worthwhile in the right situation, although I do agree it's probably more a case of minimising intake losses than actually achieving greater than atmospheric pressure.

It is possible for an engine to take it more than the cylinder volume per inlet stroke - and indeed less than it. Not hugely so, but its VE can be above 1, I believe.

It is possible for an engine to take it more than the cylinder volume per inlet stroke - and indeed less than it. Not hugely so, but its VE can be above 1, I believe.

Indeed, that's why I chose to ignore intake inertia and scavenging effects for simplicity, as in reality there's a boost from resonance that depends on a certain combination of intake header length and RPM, but with corresponding losses elsewhere in the rev range. Hence Tom's need for number-crunching to find the best compromise. Best not give him ideas about variable-length intakes, though...

even the very best race tuned n/a engines barely go above 90% volumetric efficiency, and even then it's only at one place in the rev range... i think robin hit the nail on the head.. minimise losses! ram-air does NOTHING at road speeds. fact

I'm pretty sure they can go over 100%, I've seen claims that F1 engines have to be over 115% at peak power to do that. There's a guy claiming 137% for a N/A engine, which is disputed, but there are plenty of people saying that over 100% is possible, and indeed from what I'd read up on years ago (when tuning using a megasquirt) they said the same in a well-tuned engine...

I'm pretty sure you can't go above 100% without scavenge effects and/or achieving a plenum pressure above the present atmospheric. If anyone thinks you can, perhaps they could tell us where this air is coming from?

It comes in the same way all the other air does...