Hello guys,I just finished tuning my lovely Gtv 2,0 V6 TB into a 3,0 V6 12v TB,and wanted to share my project with you.
Starting from my completely stock 33000 km Gtv,i was not satisfied about its engine (i love its sound,but not its power and performance),so...Instead of tuning the stock engine,i decided to start from a 3,0 12v engine from a '97 164 3,0 12v (motor code 66303).
My target was reaching absolutly reliable 400cv and more than 50 kgm,so i began.
I used CPS pistons designed by me about surface,rings height and position,and valve places (i don't remember the right name...
). Bore 93,4mm instead of 93 stock pistons,volume chamber 66cc instead of 58cc,so the compression ratio is 8,5:1. Obviously bored and honed stock liners.
After long sessions on the dyno with another V6 alfa engine, I decided to use sotck conrods,enough for more than 500 cv. Polished and balanced with <0,1gr tolerance by me. New bolts and bearings.
The crankshaft had no wear,so i just cleaned the oil ducts, and polished the main journals and rod journals.
I like hearing sport engines revving up with lightened flywheel,so i decided to do this on my engine,but this is a V6 engine,so i had to re-balance the main pulley-crankshaft-flywheel-clutch assembly,and is it not an easy thing,because you have to balance every piece,individually and then the assembly.
Stock oil and water pump are enough for my project,so i decided not to upgrade them. I only built a new water pump pulley with a smaller diameter. (-5%).
The hardest part of the project. I made a flow test on a flow bench,and figured out that intake and exhaust ports are not enough,IMHO,so i machined,polished and put again on the bench to improve head ports,using stock intake valves,and Nimonic 80 uprated exhaust valves,41mm instead of 39,5mm. I made a three angles cut of valve seats,30°-45°-60° on the intake (1,5mm width contact band),15°-45°60° on the exhaust (2mm width).
New valve guides on both sides,new oil seals.
After many hours on the dyno,i realized that 2,0 TB camshafts (Int lift: 7,6mm.Ex lift: 8,5mm.
28°-59° 65°-38°, 267° 283° duration) were not so good,so i tried to use stock 3,0 12v camshafts (Int lift: 9,1mm. Ex lift: 8,5mm. 32°-67° 59°-33°,279° 272° duration) were much better. Unlike many turbocharged engines,which need short exhaust duration and overlaps, my V6 engine needs longer exhaust durations,because of long exhaust manifolds that require long exhaust pulse.
Stock manifold,U pipes and turbocharger support can provide a good work,if you study and apply the right camshafts. The downpipe is a brand new one,handmade with an 80 inner diameter,the remaining tube is a stainless 76mm,including bends,with two silencers.
To be continued...
P.S.: Tomorrow,with pics...