OK, so I will shortly have a blank canvas again and am looking to build a normally aspirated mk1 8v trackday car. It will be a 1.8 unit simply due to the abundance and cheapness of spares compared to the 1.6 or small block 2.0. Questions: solid or hydraulic tappets? The engine will get some degree of porting and possibly a mental cam. Any benefit in solid tappets? injection system? It will initially run Digi 2 on a standard engine. When the head/cam is done will Digi 2 be of any benefit without getting a chip? Or should I just go MS? Or back to k-jet? gearbox? I have a rebuilt 16v box - any downside to using this? Any advice/experience much appreciated.
My previous 1800 was: PB block - TSR Pack D head - solid lifters - 285` cam - KJet plus K Star KS301 - lightened flywheel Revved beautifully to 7200 self imposed (OMEX) limit and totally reliable in 10,000 miles of road / track / hillclimbing and sprinting. Power 143.5bhp @ 6770 - flywheel Power 105.5 at the wheels Torque 117lb/ft @ 4430 (Air temp was 27`C) Gearbox - Initially an 8v 1600 GTI fully rebuilt with Quaife ATB, only problem was a broken 5th gear. Since uprated with a Gemini CR gearset and no problems. Did ~ 160 5k standing starts with no other problems apart from wheelspin !!! - SACHS power clutch. For a mental cam (300`+ I assume) then solid would be adviseable; no experience of Digi; get the gearbox done right first time ! Good luck .....
Why? it will cost you a grand to get same output as standard 16V. I dont agree with this "its got more torque" business
Correct Gary ............ thank you. My previous bog standard 1800 16V Mk2 gave 150bhp at the flywheel and 131lb/ft torque... only `mod` was a K&N air filter.
Anyway back to the thread: If you really want an 8v then try to chuck something together yourself or with a friend otherwise get a previous project from someone to save you a LOT of money, maybe a 2.0 if you can find one.
ive half built my new 8v, i got a 30k engine out of a cupra sport ibiza (agg code) and removed the crank flywheel clutch housing etc for lightening and balancing and have the journals polished.. then the head is pb p&p etc,gs2h cam with vernier... the next mod is to source another inlet manifold and have it cut about and modded so i can get some bike carbs to fit but i want them angled away for the zorst manifold to reduce the hot air fed in.. im trying to build this all myself only pain in the ass is waiting for machine shop (taking ages) my goal is a fast snappy revving 8v 2.0l which obviously makes decent power..
the engine cost me 150 complete, had the head cam etc already... the machine work is 80 (mates rates) and then the cost of gaskets seals bolts etc maybe 300 ish
I Maybe able to help... If it's main use is for track days and you want to use a "mental" type cam (300 degree's or more) then solid type tappets are the way to go. The cam for a solid head can usefully use a higher valve acceleration profile for the same duration than a hydraulic type cam due to hydraulic lifters not liking to be "squeezed" too fast. Plus, a real radical cam (again due to valve acceleration) will need a bigger diameter cam bucket which is'nt generally available off the shelf like a solid one is. If going down the modified head route, if you want the engine to evolve over time when funds permit perhaps, you could start with a ported head on standard valves then upgrade to bigger valves at a later date (along with maybe bigger buckets if the cam spec requires it). You'll be able to get up-to around 160-170hp on the standard injection system (with tweeks) for track use but the camshaft needed to do so wont be at all nice on idle and low-down responce. For more power than that, yr going to need to look towards throttle bodies & engine management ([:^(] ) of for a cheaper option, some second hand DCOE Webers and a standard type dizzy & ignition pack will do an exellent job. If it's to see "a lot" of road use as well as track days and you want more than 160hp then t/b's & management are going to be needed, if not, carbs will do a fine job (they'll even be acceptable on the road with a fairly big cam and big chokes for "light" traffic use "if" set up correctly ) A standard 16v box should be fine (depending on condition/build) as you should'nt be needing to play "beat the syncro" when changing gear just for track fun (though easier said than done !) and i've seen them cope well enough with 240hp without breaking everytime out so 8v power shouldnt be too much problem (i use an 020 8v box with 190+hp, aggressive-ish starts & gearchanges and have'nt broken it in 3 years use). Bottom end... Standard crank will cope with 8k+. Rods & pistons, well that will depend again on the ultimate power you want to aim for and what sort of compression ratio you run. Hope this helps to start with.