bike carbs on 2.0l 8v ?

opps, duno what happened there !

 

just won set on e bay so no turning back nowcant wait to hear that induction roar

 

Induction roar eh.... well in case you hav'nt already seen it...


http://video.google.com/videosearch?q=hillclimb+golf


Turn it up....

 

Im shocked at some of the BHP figures being banded about here...

Would be good to see how these carb fed 8v motors stack up against a high spec 16v on the same day/RR...I assume these BHP figs are from an accurate "Dyno Dynamics" RR??

Im sure some of the best old F3 2L 8v motors struggled to get anywhere near a true 200BHP....

Surely the lack of valve area & consequent lack of top end breathing is gonna compromise the peak BHP figure, even if torque is healthy?

 

if its any help to any one i have a few sets of GSXR carbs sat in my garage as spares as i have just sold my GSXr's for an new one and they are no good for my valvers

 

I think the thing with the F3 engines were that (i believe) they all ran on restrictors and mostly had peak power fairly low (lack of top end breathing ?)in the rpm range (5-5/6-5 rpm ?) thus not producing big numbers. The old hotrod spec engines though without restrictions (big carbs/choke's, VERY big cams, 8k+ rpm)produced in the region of 210-220hp (allegedly) from the likes of Mass & John Toovey, and i've seen claims of 230hp for 2ltr carb-feed 8v'ers (though i do think thats a bit OTT).


I would ALSO think that the valve area available would'nt produce the results... but they seem too. 4-1, short primary off-the-shelf exhaust manifolds (Ashley) shouldnt produce the low-end drivability with a race cam but it can (well it does in mine at least). A medium 4-1 on a race/hillclimb Ford (-only kidding) Kent crossflow KILLS the low/mid range but it does'nt have the same effect on an 8v VW.


Some 8v engines are VERY under-rated (the 8v, yes 8v Vauxhall is another !), some things work better than theory suggests.


Dunno about the claimed "near 200hp 8v on 32mm chokes" (engine dyno power or "inflated" run-down loss from a r/r ?) but mine was run on a Sun Ramrolling road (the VERY same R/R that a certain Mad 20v was run/developed on, you all know what power/how well THAT goes)with power measured at the wheels and the flywheel figure calculated with a.. err.. calculator ! VW uk "allegedly" claim a 15% approx transmission loss, cant imagine (in fact i dont believe) they would be far out.


Peformance quantification... (and no its not meant as a trumpet blow) There is'nt (currently) a Pug/Escort/Elan/Elise up to 1800cc (all VERY well developed/light-weight/some injected/dog-box's/experienced drivers/140-155 ATW poweretc) that can (currently) beat my 8v-er on a hill, wet or dry.


Certainly hoping to get along to R/R day (p'raps a TSR day as its fairly close) as soon as i repair my trailer (hopefully VERY soon).

 

Would be good to see what it would do....

Maybe try joining us other SW peeps at SWDUBS.CO.UK

 

TSR's rollers are very optimistic IMO. My old 1900 made 112@wheels on the same rollers as mr hilclimber and Mad 20v and the following day made 130@wheels on TSR's rollers.

Mike at Rat Racing is currently rebuilding a customers VW F3 Judd engine, The head is based on a 1.6 Mk1 GTI head and Mike said the inlet valves are arround 45mm with the exhaust valves not far behind offset guides, phosphor bronze seats and alot of machineing to clerance the cam lobes.

I've got no doubt a properly developed 1.8 8v running un restricted ITB's and standalong managment could easily break the true 200bhp barrier

 

I'll take a look, thanks.

 

Did'nt Grahams show something like 208 atw at a r/r day at tsr not long after it ran on ours at 206 ? (the EXACT numbers maybe a couple out but it was in that ball park)


Is the Judd still on a restrictor/going back into a historic F3 ?


Mine's based on a carb head casting (no injector holes) but it would never take valves that size ([:^(]) being a chambered 1800 style head. We went up slightly on the valve size's from the hotrod spec (now at 41.91 / 35.5 from memory) but that was as big as would fit together (its tight!).

 

Thing is there isn't two rolling roads that read the same.

Ian took his mk1 along to Emerald last week to an RR day and it did 173bhp / 151lb/ft, where as at Stealth it did 180bhp /155lb/ft last summer after he fitted the ABF with flowed head / KR cams.

Not sure on the ATW figures.
Edited by: GVK

 

100% true !


I'm also (and no doubt it's been debated here before so i really dont wanna start one) not a fan of flywheel figures obtained from r/r run down losses, unless the wheel power obtainedis shown as well for a comparison.


They seem to be closer to realistic differences these days (especially from the reputable tuners) though some of what the "comics" print for turbo cars are still laughable (mostly of the F**D persuasion!) though VW figures seem in the ball park. what it shows at the wheels is what pulls (or pushes) the car up the road, Rolling roads are for wheel power, "Dyno's" are for engine power.

 

Hehe, the debate about coast down losses is about as old as which is best? 8v or 16v mk2s?! lol!!

What I don't agree with is tho is this standard 12-15% losses claimed by VW (and those Yanks on Vortex), I don't think for one minute that all cars of the same model will have the same running losses through the drive train, unless they all have the same - gearboxes,gear oil,wheel bearings,tyres, tyre pressures, geometry and all have the same tension applied to the ratchet straps used to tie down the car when running on the rollers.. etc etc etc

Interesting thread about such things here

As mentioned before many times, it's the before and afer tuning results on an RR that are important, else you end up playing the numbers game.
Edited by: GVK

 

Thought you'd say the first bit !


As for the rest.... pretty much sums it up (without a "my ways better than yours" debate!). I think its one of those subjects that everyone will have their own interpretation ofbeing "the right way" and certainly as far as tuning goes, differences rather than absolutes are the important issue. How a car performs normally paints a truer picture.... until you take into account weight/gearing/tyres/suspension/brakes... aaaaaggggghhhhhh.....[:^(]


Crank scrapers anyone !!!
Edited by: mr hillclimber