Vc496

Been awhile finally got back to head bought myself a new toy and got side tracked sat down the other down marked out and roughed out the exhaust ports

Down to the short turn

Head Welded Ready For Some Metal Removal

Bruce Here are the figures all tested at 28 Std 36 mm intake and 29 mm exhaust EX Intake 100 46.5 53.8 200 84.4 93.2 250 97.9 111.4 300 105.8 125.1 350 110.8 134.2 400 115.3 141 450 117.1 146 500 120.5 147

Bruce Yeah I know about them but with the changes to the head it will allow the runner to rise higher than standard which will move the carbies up further and due to the gap between the strut towers being wider at the top will give more clearance.

No I have not compared any notes just spent many hours modifying the exhaust port both in shape and in the chamber. Intake was easy. Found a lot in chamber design hence why it is getting welded. Yes you are right the std big port air speed is way to slow(virtually none across the floor and slowly got better towards the roof). If you ran a bigger valve with the untouched port and turned it 8000 plus it would work well. That why I stayed with the small port and std valve and modified it. Good airspeed all the way through the lift up to 500 which will give good power all through to approx 7500 with good throttle response for coming out of corners. Hopefully I will have the trial head digitised and then be able to tweak the ports on cad and run cfd on them and hopefully have a cnc program for them. May take a while eventually I would like to be able to do a CNC head and CNC manifold package. Cam shaft I have not yet decided but will be in the 450 to 500 lift range and duration at 50 somewhere between 240-260 Should be able to run good compression without milling to much of the head due to the chamber design.

Bruce I used my local university to scan it for me. With regards to improvements we are trying to achieve a more direct runner path to port to suit the modified head. If it works I am going to 3D print a test piece for trial fitting purposes and then I can change things on the Cad model. Looking to have a billet CNC one made it will be a slow process but hopfully it will work.

3D scanned ready to reverse engineer and make it work properly instead of being a good boat anchor. The fun begins

Our ole 4k seat removed areas marked off for welding and then lots of grinding lots of grinding

Being spending a bit of spare time working with a 4K small port head using the std 36mm intake and 29mm exhaust for a good friend. After carryout some tests on the small and big port heads found that the bigport airspeed was way to low so I decided to rework the smallport and to find that it outperformed the big port. Modified the small port intake to the correct cross sectional area required for the valve size great average airspeed through out the port . Exhaust was a bit of a problem (no air speed on the floor)but with some out of the square thinking got it working really well to. 1st pic std intake bigport cyl 4. Cly 8 modified smart port using std 36mm valve with good air speed across the entire port. 2nd pic std exhaust port cyl2. modified exhaust cyl7 using std 29mm valve with good airspeed across the entire port.