hi all just after a few ideas about my vk v8 motor just got bottom end of motor back 308 355 come crank hypotetic flat top piston all machined and balanced gearbox- m21 possible changing to t5 in the future but just want to get car up and running for now diff- salisbury 355 ratio lsd car for street use been avoiding top end but now decisions need to be made i know vn efi heads are probable the better option but i have a set of brocky heads and manifold and am trying to stay as original as possilbe. is there a great difference in power between the 2 and will you notice the difference on the street and what cam to use for vn head and what cam for brocky heads thank for the ideas
if you are going with a stroker, then the early heads are only going to hold the engine back (without some serious work) Definitely go with the VN heads.
Im in the same boat here with my new VK project I have a set of VN heads and a set of B cast heads and I cant make a decision between outright power & keeping it original to the point Im thinking about building 2 engines. The VN heads out of the box flow well and you will get great performance, you will struggle with the b cast heads You could always weld a B onto a set of VN heads & use a carbie manifold on them only the port pattern will tell them appart it would fool the uneducated scott
Hey guys I'm looking at doing the same to my VK. But again I'm undecided between the two. Have looked at the Crane compucam276 which was recommended for my set up and also the compucam286, but the latter of the two requires at least 9.5 compression ratio to work best. Looking at the Gregory's manual the standard 308 only has 9.2 : 1 so how would we go if we bolted the VN heads straight on?? Anyone more clued up on this? Asked the guys at Southern Engine Reconditioning about it (good guys) and they reckon you'd have the measure the flow of the heads to see what they're doing as its apparently not as simple as taking a skim of of the heads to raise compression. God damn it's never easy is it!
Alot goes into it for a "blue printed" but you can get pretty close from looking at other results. Big differece in pricing as well They not only measure volume of air but velocity as well even turbulence plays a part. Of course compression ratio will play a part but I dont think you would see a big difference between 9.2-9.5 comp, might be a bit friendlier to our crap fuel. You can cc your heads with a light oil and an accurate measuing dropper or accurate scales, you just need to make sure the valves dont leak when you fill the chamber VNs ran 8.4:1 compression, just be careful decking heads you dont have a valve come down and hit the side of the bore, been there and done that and it wasnt pretty , I wouldnt raise the compression too much unless you dont care about running 98 fuel Scott
I think if you have to ask then you really don't need VN heads, just stick the B cast heads on it, they were good enough for the old 308's back in the day to give the 351's grief at the track.
