WRC/GRP-A YB Power/Torque figures
 

I've alway wanted to know how WRC/GRP-A YB achieved 600nm of torque and only 300bhp.

I know they where high comp and they have 32/34mm turbo restrictors but can someone explain the science behind this, ie how a restrictor effects power and not torque etc What sort of boost did they run?
I've seen a IHI turbo and they are tiny! it just amazes me the torque they produce! Has anyone got a plotted power graph for a WRC engine? would love to see how the power and torque rise on these and where the peak power is etc

Is there anyway of appyling these methods to other YB's combinations so you could have for instance a 400bhp engine with 500lbs of torque??

Paul im pretty sure they run nearly 3 bar... but someone who knows for definite will reply i dare say!

LOOOOOOOOOOOOOADS of midrange boost 3-4bar is what ive been told

i think they were built for big power but the restrictors just limited the peak BHP because of air flow. however its not just a simple as removing the restrictor to just magically get big bhp due to the spec of the engine being based on running a restrictor.

Thats what I always understood it to be :oops:

its very simple!
the restrictor restricts ultimate air flow! so they HAVENT got the option of running big bhp at high engine revs as this would require alot of air!
so what they do instead is make the engine produce the power lower down in the rev range!

Its only about 440ftlb. Hardly an amazing achievement on a high compression turbocharged motor with a few bar of boost.

i disagree,, i think its a great achievement to have that torque of that level at them sorts of revs and still be within the rules!

Power is made by torque and revs, torque isnt made by power, so its perfectly normal to have tons of torque without the power if your not revving and are running loadsa boost.

The way they made it is mostly down to big big boost pressure.
Though being able to "only" have 300bhp or so and not having to rev meant they could run mega high comp, very low duration cams, small ports, etc etc, which all help torque too, but in a much smaller way.

If a 400bhp "normal" spec mega boost and mild cams YB stopped revving at 4.5k or so itd also be pushing similar numbers, though obv not as good as they have been specced to breath well at higher rpm too, which obv reduces low down power and torque.

thats why foci world car engines are only 30k on an exchange basic!!

440lb/ft?which engine wrc engines is that on then?with what size restrictor?

Paul you know your going to break things with 500lb's :cry: Mark Shead makes 500hp/500lb with 2.6 bar on a GT30 on a DD rolling road, the print out is on here some where...

He was just quoting Pauls 600nm

Tim whats the average life of a WRC engine and turbo?

it all in the build really, we dont spec for high revs just loads of torque with boost as early as possible in massive amounts :shocked: as for the IHI beinga small turbo, its not as small as you may think, the compressor volume is huge, the exhaus housing looks small, i cant remember its ratio, im sure Ian will remind me :grin:

ive often though that the MD240RS thingy turbo 'may' make a good rally turbo due to its ratios of hot/cold side - any thoughts on that ? (sorry to distract the post)


also the 300hp thingy - is quite a lot on gravel i can tell thee ! ;-)

the engine & turbo have to do 2 rallys the they get a full rebuild

no they dont, depends on th e'linked' rules as to how long the engine must last, but clubman group a cars and clubman use WRC car will easily do a full season if nothing mechanical breaks.

I'll think you'll find the figure's a little higher, an N12 subaru, thats a group 'n' car will make 560 nm on a 32mm restrictor.....

Part of the new rule changes for 2008 mean teams are only allowed a maximum of 5 engines per car and they have to then use one engine for 3 'linked' rallies (to increase reliability) if they defy this rule the FIA impose a penalty, they have just done Citreon on rally mexico, for breaking this rule, although the FIA recinded the penalty when Citreon put the old engine back in the car....

Average engine i'd guess now they'd be looking at 3000km as on average your looking 1000km per rally incl the shakedown (not all competetive)....

beat me too it mark....lol...took me 10 mins to write that.....lol

ive just re read the thread title,it says wrc yb engines,not the current crop of wrc engines.:oops:

I am not that experimented as Ian or mr.Finch but what I have seen over the years is that a WRC YB engine produced around 350bhp, but for torque I have never seen really any real figure. Between 650 and 750Nm depending of age and tuner.

Recent WRC cars are around the 1000Nm barrier. Spoken to a Bozian engineer 2 years ago (307 WRC) he told me the 307 had more than 1000Nm of torque. Basically I have never seen the real figures, but I assume the modern WRC cars are quite near the 1000 barrier.

The old Octavia was doing between 600 and 750Nm between versions, and this was an old car...

:)

why the fuck do folk quote NM figures just quote ft/lb we dont like fooling stupid people in thinking its ft/lb

ft/lb is an old english measurement,NM is an international measurement.

do you really think citreon,subaru,mitsubishi,suzuki etc etc would use feet and pounds to measure anything?

what an easy conversion from ftlb to NM?

NM x 0.73756 = lb/ft

Evening Dan :DD:

and what about then other way round?

Yo,

lb/ft x 1.35556 = NM

:cool:

just to help you out, if you ever want to know "the other way around" for a conversion formula you can do in inverse of the original conversion!

so just 1/original conversion number

so 1/0.73756=1.3558218992353164488312815228592

One 1994 GpA car here in Germany was rebuilt (YB engine, originally mountune) at a well known tuner in Kent last year.

On the dyno it produced max 414lbft and 312bhp. (3000 - 6500rpm)



kenny.

I bought a group A turbo of a guy who had a group A Escort, he was running 280bhp with 2.5bars of boost, and 300bhp with 2.8bars if it can help. :)

that sounds about right kenny for a group a engine. the wrc engines make about 500 lbs ft of torque and about 315-320 bhp
wrc engines dont have to run loads of boost to make the figures.
you run as much boost as you can but you have to measure the depression ( i think its that ) so when the depression gets too high you back the boost off and have to come to a compromise between the 2