Title should read High Power Big CC ..... Going to build a big 8V based on the Eurospec 42/35mm head I have recently acquired. Couple of things that the clubgti knowledge base could answer; Availability of a big bore exhaust manifold. The port is real big, so I need a manifold at least the full size of an exhaust gasket. What do people use? (Mk1 or mk2, not sure of the application) I have bought a double weber inlet manifold that needs port matching? Who is good? Thinking twin 40 , 42 or 45 jenveys. What'll suit a GS6 cam with 12:1 com? Anybody got any bits that may help me out? Jon
Will it be a 1.6 or 2.0 engine ? A GS6 cam sounds me bit heavy... with 316 duration and 101 degr LSA and lots overlap...
It will be 2L or slightly over if I go for a rebore. I run a GS6 in my full race 1600 EG and it is 'heavy', like a sledgehammer.. So, I was thinking of downcamming the 1588 to 276 degrees, 11.3mm and 2.5mm at TDC , as an experiment (have a schrick cam already) and trying it on the rollers. It is hasn't lost too much at the mid/top end, using the GS6 in a 'big' motor where it should be less 'cammy' Jon
Last nights brainstorm was to use the short ABF flat top pistons in a long block 8V. Gudgeon pin is the same diameter. But I think I will have too much CR. Looking to lose 10cc from the volume above to get the CR up on std parts. (560/60 to 550/50 if that makes sense). So now thinking a 2mm block skim and a little bit of piston shaving instead Jon
To get 12 /1 CR on a 2 L > 496 / 11 = 45 cc OR 496 + 45 = 541/45 = 12 So indeed, it will need either a head skim OR skim block and machine a dome onto the piston OR skim a bit of both > head and block
Block is away getting 1.5mm off the top, I will skim the pistons so they protrude 0.75mm or maybe 1mm which will also shrink the bowl volume a small amount. There's not a lot of material before the top ring to play with. Pondering whether to shorten the skirts also 10 or 15mm, they are a long piston. It'll be a real budget short engine, if this all works... As usual with VW's (that have been serviced...) the crank is mint... Regarding throttle bodies, my gut feeling is that 40's should be enough, although I'm very open to comment on this. I know bike engines massively oversize theirs Jon
As a 2 L 16V on 45 mm and a 1600 16V on 42mm trottle bodies can make very serious power levels .. If we go from 45 mm or 15,9 sq cm, if we take 80% of that = 12,7 sq cm > thats 40 mm ( 12,56 )
Thanks. Biggest chokes for 45dcoe is a 40, so not having any choke............ Any thoughts on shortening piston skirts? Jon
As the ventury is relative short in lenght within a 45 mm carb housing + trumpets…. it might give not to much restricion… On make a shorter piston skirt ...10 - 15 mm sounds me much… as the piston get less guided in bore > piston slap...
No, its just I've got 6 race engines and my wages wont stretch forever. I'll take some pics and post them, the ABF is really short, these 8V ones must be Victorian, the skirts are that long. There is a 'natural' internal rib that I will skim up to, I think. About 9mm off, I will post up some pics. Jon
Other cams in 'stock' GS2 (too mild), GS3 (prob right for a 1600) and some wacky schrick thing that someone may recognize comment on please, as above; Left hand one is a GS3 (base circle 36mm , presumably std) Lobe max 47.7, so 11.7mm lift Right one is a flat topped shrick monster thing. Base circle 38, peak 49.2 so 11.2mm lift Does anyone recognize this as a slick 50 special? Or what? It must have a monster area under the curve. Ive labelled it as 314 deg duration, cant remember why... Jon
Also piston skirt comparisons; Left one is 8v compared to ABF on the right Must be able to skim the 8v one down, possibly to that natural step? Comments, as always, appreciated Jon
Its a 'long stroke 8V so it'll be about done by 7500 I'm guessing. Probably do 1000 miles ......... in about 6 years. LOL Jon
As you talked about ABF pistons in post 4 …. i tought you would use these , not 8V piston GS3 cam is the way to go > 300 degree / 102 LSA / 11,6 mm lift
Thanks, I have misled you, the 8v pistons can have their 'Victorian skirts' trimmed a bit, I think. Agree a GS6 is a bit OTT for a 1600, so I will fit the GS3 and visit the rollers again. Interesting to share the results on here. Any idea what that lumpy schrick is? Jon
8V piston can indeed trimmed till that ridge inside or even a bit more.... it doesnt need to do lots miles Even for a 2.0 L engine the GS3 would do very well... Often engines get cams who are OTT , just get a good overall performing engine that is strong from below... I have no idea on the schrick cam...
