Thread: VN heads
17-03-2012, 12:41 PM #16
17-03-2012, 02:02 PM #17
17-03-2012, 02:11 PM #18
Even when people talk about CSA, theres different kinds of CSA .... Straight port, line of sight, soft turns not abrupt, no dead areas and heads that are the opposite ... I think working out what mCSA you need as just a number isnt quite enough. it has to also look 'nice'
17-03-2012, 03:30 PM #19
no abrupt changes in csa and line of sight are very important, some heads due to the design are impossible to make an ideal port but we can do as much as we can to improve it with in the limits of the casting
a lot of the time the cross sections elswhere in the port are not considered and guys only focus on the so called pushrod pinch or when they raise the roof they forget about what they have to do to the intake manifold to get a nice straight line of sight in to the runner it usually requires adding material as well. after years of looking at ports you get an idea of what a nice looking port looks like shape wise and sometimes describing it in words is as hard as doing the work.
tony hit the nail on the head with the width over height factor, cathedral heads are the worst offenders and focus to much air in the centre of the short turn hence the high lift back up issues
Last edited by HPE PETE; 17-03-2012 at 03:33 PM.
17-03-2012, 03:32 PM #20
- Join Date
- Aug 2008
17-03-2012, 03:47 PM #21
in that case...stock untouched ( not even deburred ) 1.598 pinch 11.68 @ 113.5mph...lbs? what ever a std weight street trim torana with full exhaust system and 9 inch is with 230 @ 50 hyd cam 308ci performer intake
saying that the tiny tiny pinch isnt hurting the mild 6000 rpm combo that much.. WOW thats small we didnt measure the pinch cause we didnt care what it was just a bowl job
Actrol im impressed you have kept the ST and pinch measurements for the last 20years, good stuff
17-03-2012, 04:01 PM #22
tk i noticed the stock rocker posts what rockers you using?
17-03-2012, 04:04 PM #23
- Join Date
- Jul 2007
YT platinum bolt ons - the ones with the nice body that bolt up like the street terra cast ones.
Don't need more than that for a solid FT.
Just finished Justins stripmaster for the E85 253 & now I'm off home.
17-03-2012, 04:46 PM #24
considering the lobes we use then the springs we hang off the 8mm LS1 rocker bolts that seems a fair call, machining screw in studs is never fun.
17-03-2012, 07:11 PM #25
did these ones a couple of months ago i wouldnt call them ported as **** but they are still a nice set of heads, they are for a mate thats building an engine for his mate with a camtech 258 264 108 or 109 lsa VK commy
it was sort of a budget job as we werent starting from scatch more of a make it work job, they were originally ported by jack bros and flowed 268cfm with a 2.02 i dont have finished product pics but heres a couple of them getting done
port height @ pushrod 2.050
port width @ pushrod 1.244
CSA @ pushrod not including radius 2.550"
we put a 2.055 1.625 ferreas in them
this is with the comp plus ferreas we used in the heads which arent the best flowing valve for a holden head, with holdens the cheap ones flow better
.400 238.6 490hp
.500 270.3 556hp
.550 277.4 570hp
.600 291.2 599hp
.650 297.3 611hp
.700 301.1 619hp
.750 301.0 619hp
i also tested them with a valve we machined from a 2.08 down to 2.055 and it flowed more in the low-mid lift and 303cfm up top even though this head has better than average mid lift flow, then @ 500 its starting to move some air, exactly what we wanted for this combo
good low and mid lift flow comes from a good valve job with the nice angles on the seat and the valve, up top the seat does not affect flow by much at all but the valve angles still come in to play, sometimes the back cut angle can loose low lift but gain high lift flow and can even stop a head from nosing over up top, in this case we opted for good flow through out the range giving away a few cfm up top but fattening flow in the 500 lift region
these heads are nothing overly special no tricks or anything fancy
heres the 3 different valves we tested the 2.055 comp plus ferrea is on the left the 2.055 manley severe duty is in the middle and the modified 2.08 cut down to 2.055 on the right
notice the seat to chamber transition is not even around the valve this is how is was before we did the chambers
after we cut the seats we blend the chamber in to the top cut so its nice and even all the way around, this is not the same head as i dont have a close up pic of the finished product but this is how it looks after we blend tthe chamber to the top cut
Last edited by HPE PETE; 17-03-2012 at 08:08 PM.
19-03-2012, 09:05 PM #26
Some awesome looking heads boys, Pete are the COME heads you'll be doing there latest ones? Have you already seen a set and if so are they any good out of the box?
19-03-2012, 11:27 PM #27
yes they are 600 series, i havent done the full forensics on them so i havent formed an opinion yet but a quick test on the intake with a 2.08 showed 308cfm, we are porting them so we will see what they go like, the valve spacing is std so you you dont need offset rockers but you can imagine with a 2.08 1.6 the inserts are getting pretty slim
19-03-2012, 11:49 PM #28
Exhaust port way too big on the new come heads ...
31-03-2012, 11:53 PM #29
wont comment on the ex port yet but have roughed out the intakes and done chambers so far
havent had a good chance to do much with these untill a day or 2 ago
01-04-2012, 05:57 AM #30
- Join Date
- Jan 2012
- hood st
Exhausts are to big and better of with texture in the chamber......
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