Sonic Boom

iTrader: (11)

A few of you will probably have seen Keith Murrays Dialynx Audi Quattro, if not take a read:
http://fourtitude.com/features/Featu...-construction/

Would it be possible to do the same reduction to a YB engine?
Say with liners, pistons and a new crank?
Wouldn't need to rev to 10k or have 600bhp to be fair anything over 330bhp would probably suffice.

Cheers Rich

Will Pedley Racing

Sure, changing the engine geometry can achieve many advantages, however, there will always be some compromises.

Generally you would find that whilst the shorter throw crank will reduce the mean piston speed and rod angles, it will also reduce the torque. Now, that's not always a bad thing - especially if you're traction limited in the first place.

Unless you're bound by capacity restrictions (like Keith was) - it begs the question of 'why?'... It would run you to at least £2500 in my estimations to get the hardware.

Sonic Boom

iTrader: (11)

Well Keith is in Mod Prod but imagine a 4x4 1400cc Sapp in A1 Class which is Road Going Production under 2 Litre, mostly you're against Saxo's, Cilo's and 106's with the odd Elise thrown in at the sharp end.

If you could have 330bhp with 4x4 traction you'd have a class winning car.
Rich

Mark Shead

I would add 5k to what will said. It would be poss how we'll it would work no one would know till you tried it.

Mark

Madgit

Wouldn't it be a bit heavy for just a 1400 lump though?
Bigger body, transmission etc.
Those Saxos/106s can be made stupidly light.

Sonic Boom

iTrader: (11)

You can't strip them out in Road Going Production thou, the most powerful car in A1 is Tony Adams Lotus Elise which is 200bhp.
I think the additional power and 4x4 grip would out way the weigh saving of the Elise.

Dave Parr PB up Prescott in not hugely modified 330 bhp 3 Door is 48.60
Tony Adams PB up Prescott in his highly modified Elise with 200bhp is 48.92

Tony holds the Class records at all Midlands Hills.

I really do think a 1400cc 4x4 Sapp would be class winner.

Rich

CrOwSoN15

Get your engine to a machinist then

lee2cossies

iTrader: (2)

Don't nms do 1800 yb's as they have advantages over 2.0's in some areas.

boy-racer-1

How would you get around valves hitting whatever liners you fit? I think the crank mod will be so much that at high rpm it'll rattle bolts loose

Sonic Boom

iTrader: (11)

Wouldn't dream of doing it to the 3 Door, i'd start from scratch with a 4x4 Sapp

Needs to be a maximum of 1415cc to stay in the under 2 litre class with the turbo multipier

A question for the engine builders.

Rich

dissmalrs

Could you not just reduce the stroke

Down to 66mm at a guess would get you down near the 1500cc mark and then you could bring the rev limit up to get the power would need to do something to the timing gear and get good pistons and rods to cope with the extra strain

But there are 2000cc yb cutting doing 8000rpm

Standard bore x short stroke + longer rods + increased rpm I would say if a good management and set

up u could get 400bhp

BMW in the 80s had a 1500cc turbo making 1500 bhp so it can be done

I think your limitation is going to be in the cylinder head

Keeping it flowing at the higher rpm and cams and lifter the have a lift and duration to flow for the power but

And a turbo that can flow for the power but modern turbos at getting realy good and a tubular manifold will help here as well

CrOwSoN15

Wouldn't this give a ridiculously low CR?

dissmalrs

Yeah I would say that might be an issue but there is higher comp piston made for n/a cosworth yb so there might be a way in using them or getting 1 off pistons made

If we could retain a good comp it would run ok but it's gona ideal like a shit

Also you would want to get a sequential box as the rev increase would make the standard ratios do like 300mph lol

There is defo some issues but I do think it could be done

Will Pedley Racing

If you're going for a shorter crank stroke, then you need to increase the connecting rod length. If you were to try and make anything up on the pistons then the thrust loading on the piston skirts would wear them incredibly fast. By using a short stroke, long rod combination, you will achieve excellent rod ratios and reduced mean piston speeds which will allow for safe use of high rpms. Subject to your valvetrain being up to it...

dissmalrs

all in all I think in theory this is posiable but it would cost a lot of money
you will need

bespoke
crank
rods
pistons + rings
cams

solid lifters
long studed
dry sump
tubular manifold
a new inlet
better valve springs
pluss some head work
gtx turbo

managment mapping

gearbox

and all the bering, seals and oil to build

Will Pedley Racing

Yes, but how much of that would you need if you were doing an engine build anyway?

Sure, there are some bits in there that will be very custom and very expensive, but with a reduced capacity engine you will inherently make less torque, therefore, the transmission will get an easier life and potentially avoid you expensive upgrades.

Nothing is impossible, it just depends how big the development budget is.

dissmalrs

could no agree more the only reason i say a new gearbox is because the increased revs

a standard bore 90.04mm and a strok of 54.5mm would give u a cc of 1412cc ish

but i think if u went over 9000rpm then the valve spring would limit the lift due to there size to less then 25% of the valve size

that is a guess but would need to be looking at as well

Sonic Boom

iTrader: (11)

Would it be better to reduce the stroke with a custom crank and rods and pistons to suit rather than changing the bore of the block?
Rich

Mark Shead

Going to low will have a problem with valve flow and how close the bore is, As a guess I wouldn't make the bore any smaller than a 1mm overall.

Mark

Sonic Boom

iTrader: (11)

So you really need to make the reduction with a shorter stroke.

Rich

Mark Shead

Yes, Use a very long rod and use the smallest port head and have a close look at cams and inlet manifold volume and exhaust manifold tube size.

Mark

Sonic Boom

iTrader: (11)

Why a small port head Mark?
Rich

Mark Shead

As it is now a 1400cc engine and the ports will loose response and not give a power increase where it should be.

Mark

Liam G Poole

I would of thought that if you were reducing capacity then you will need it to rev high so cams and ports will be a big provider on this..

If so how will a small port head benefit a smaller capacity engine if the higher revs will be needed?

Just asking as thats just what i would think a small capacity high revving engine would need?

Chip

iTrader: (3)

Its essentially what BMW did with the megatron.

That was a block that could take 2.0 but ran at 1.5 instead.

Mark Shead

Take out nealy 30% of the engine size and see what it does to port sizes.

Mark

J1mbo

iTrader: (1)

A standard bore 90.8mm. With a 54mm stroke will give you fractionally below 1400cc
That's 22.95mm less than standard. We use a 136.5mm long rod so with the smaller crank you'd be able to use a 147.975mm rod
349.5cc per bore gives you a 1398cc
349.5cc / 46cc (an acheiveable cc from a yb head) is 7.59:cr that's with flat top pistons and no valve cut outs or head gasket.
You would have to run an intruder piston to get anywhere near a decent comp ratio.
So I would say.
The cost of billet custom crank 2.5k easy from arrows
Arrows 147.975mm rods 1k
Custom cps one off not far off 1k
And that's just for the main bottom end parts.
I'd say 10k to do a from scratch engine then your engine builder to build and map it wouldn't be unreasonable.

To be more exact you would need 43.71cc In the cylinder to get 9:1cr
6cc for a wrc headgasket

Not taking into account valve pockets that's a 8.3cc intruder piston!

MikeR

Whoa Jimbo is a font of knowledge,

Mike

Sonic Boom

iTrader: (11)

Seems like this isn't out of the question then, cheers for all the advice and information guys.
Rich

CrOwSoN15

Pinch of salt and all that

Indeed, would be interesting to see this take shape!

MONSTER

Great thread

Exactly what PF should be about

MikeR

What would make NMS go down in capacity on the infamous 3dr that was allegedly so fast?

Mike

Mark Shead

If you have the money anything can be done lol

Mark

Glenn_

iTrader: (1)

I was just about to say the same.

Its been an interesting read so far.

Sonic Boom

iTrader: (11)

I always say anything is possible with enough time and money but you usually run out of one before the other.

Rich

J1mbo

iTrader: (1)

Deffinately not, but for the cost, would you not be able to make your car competitive in the 2.0l category?

Sonic Boom

iTrader: (11)

Starting again with a new car and said engine would be a very costly move, if I spent the same money on the 3 Door would I win the over 2 litre class? Maybe?
In the few 2 years i've been doing Hillclimbing i've come to learn you need to build a car for hillclimbing any kind of compromise just isn't enough.
So i'd love to build 1.4 4x4 sapp to do that i'd have to sell the 3 Door so in reality I'll probably just pump more money into the 3 Door turning it more and more in a sole purpose hillclimb car (within the rules of the class)
Until such a day comes I can afford a V8 Judd Single Seater
Rich

J1mbo

iTrader: (1)

I understand what your saying, Difficult to know which way to go!

The Youth.

iTrader: (1)

totally understand where SB is going here
My championship runs similar rules ie a 70% capacity increase for forced induction

I think the capacity I would need from my YB to be in the under 2.0 class would be 1180 lol

Problem with it is I get beat now by class D cars (under 1600CC!!) because engine mods are free so we have saxo's 106 and 205's that weigh about 700 kilos and have over 220 BHP!! my lardy thing (1170 plus driver) had 360 bhp last time out
So I would find myself further down the grid but in with a chance of a class C (under 2 litre ) win.

steve