As I'm rebuilding my engine at the moment I've been thinking a bit recently about tuning potential and various budget options.
Just thinking aloud really, but the new duratec 2.3 which caterham are using in their new car is an undersquare (ie stroke bigger than bore) with
dimensions 87.5mm bore x 94mm stroke, giving a capacity of 2.26 (rounded upto 2.3) litres.
The standard vauxhall xe is 86 x 86mm bore, though a 2.2 ecotec was produced (in frontera, sintra, omega) with a slightly taller block and a longer
stroke: 86 x 94.6mm. Now if this was bored out to 88mm it would be ever so close cylinder dimensions wise to the new duratec. It would give 88x94.6mm
and be 2.301 litres by my calcualtions. With an xe head on this could be an interesting prospect! I'd be guessing you'd see a 15-20%
increase in power from the extra capacity and probably more torque too from the longer stroke..
I'm curious as to what people think of this idea or if anyone knows of it having already been done?
I've read around on the web and for high revving engines under square is not desirable, due to the longer stroke of the crank and shorter rods
the rod angle is increased and piston speeds are increased and general stress on the engine components/bearings is higher.
That said, cosworth are building 200 and 260bhp spec 2.3 duratec's for the new caterham csr!
my other though was whether the new alloy block vauxhall engine has the same cylinder and water jacket spacing as the old ecotec/xe block. The new
engine is called an ecotec and shares the bore and stroke dimensions with earlier ecotec engines, but i know the intake and exhaust on the head is
reversed by comparison to the iron block ecotec head and it is of course chain driven as opposed to belt driven, but still would be a cheap light
block if the xe head were to fit and there is also a 2.3 derivative of this alloy block too.
comments/discuss?!
Ned.
[Edited on 8/12/04 by ned]
Dave Andrews would be a good person to ask about this.
James
A mate fo mine 'made' a race engine from a 2.2 Sintra 16v motor, but that was converted back to 8v (regulations). Twas a storming engine
though...Note that the block is a bit taller on these engines.
You probably wouldn't gain much, if any power from dropping an XE head on a 2.2 (all other things being as equal as they can be...), when
comparing it to an XE. You are likely to gain an increase in torque, and it is likely to be lower down in the rpm range too.
The absolute power figures are unlikely to be affected a great deal, for the simple reason that to get more power, you need to get more air/fuel in,
and more exhaust out. And as that (in this discussion at least) will be controlled by the design of the cylinder head, it isn't likely to make a
big difference.
Thanks stu, food for thought..
I have read that the xe head will breath to around 300bhp, one of the limiting factors being getting the fuel/air into the engine, now obviously
porting helps on a NA engine and also a big valve head. To get big valves/better flow into the cylinders it is better to use an 88mm bore block as
this gives more surface area for valves to flow into the cylinders. an example would be the yb which i believe is 90mm bore and has bigger valves as
standard..
My line of thought is that to produce a good fast road engine it idealy needs to have plenty of both power and torque, the xe I know is a torquey
engine to start with, but if you were only to rev the engine to say 7500 you could do this with a standard 2.2 bottom end bored out to 88mm with
standard crank and rods this might be a worthwhile gain. i'd be curious to know how a big valve head would work in a lower rev engine like this
as I know most big valve heads are in high revving race engine scenario's.
the 2.2 solution might be cheaper than getting an xe to rev above 7.5k as you get more torque/power/performance without the need for steel bottom end
or forged pistons. I believe that above 7.5k on the 2.2 you'd need steel bottom end and might be better off going a different route to get the
power, like a touring car (88/90mm?) spec crank or something.
From experience of high revving xe's they get expensive, uprated springs, collets, solid lifters etc etc so as siad just thinking about
alternatives.
other thoughts were on a supercharger, but i can find very little info on this and it appears a very uncommon conversion for the xe as the c20let
(calibra turbo) engine is used instead and can ultimately go to 400bhp ish.
Ned.
There is an interesting Article on Porting the XE Head in the latest Practicle Performance Car magazine.
It might be of use to you?
The problem is, it i quite dificult to get a copy of it. Most newsagents have sold out.
HTH,
Chris.
thanks for the tip, will see if i can get hold of a copy..
Ned.
go find yourself a 2.3 volvo engine , fit a 16v head and turbo , instant 250 hp .(500 the norm in racers at 2 bar) youve only got engine weight to
consider .
or a really cheap one would be 8v turbo , mines currently 146 at the wheels , at one bar (220 ft/lbs) , sorry i know its off topic - but somebody has
to inform people !
quote:
Originally posted by Volvorsport
go find yourself a 2.3 volvo engine , fit a 16v head and turbo , instant 250 hp .(500 the norm in racers at 2 bar) youve only got engine weight to consider .
or a really cheap one would be 8v turbo , mines currently 146 at the wheels , at one bar (220 ft/lbs) , sorry i know its off topic - but somebody has to inform people !
got hold of ppc, penultimate copy in guildford high street whsmiths
quote:
Originally posted by ned
got hold of ppc, penultimate copy in guildford high street whsmiths
only if you're good for santa 