after thoroughly enjoying myself at WSID Sydney VW drags , I have decided to try and get some more power from my 2733 type-4 engine for Warwick .
I have removed the engine to do some porting and polishing on my heads .
Last dyno session produced 140hp @ the wheels and now I am hoping for 153.9+ 😉
when I pulled the heads off and stripped them I found that 2 inlet valves were not sealing correctly . I am also up-sizing my exhaust primary tubes and dad will help me make a new exhaust system
After stripping the heads we decided that welding was necessary on the inlet and exhaust ports for extra porting. We were concerned about valve seats coming loose whilst being welded so we decided to start with a new pair of heads and keep these as a spare pair. The inlet and exhaust ports have been welded and re-faced.
I have begun porting the inlet ports. I have also decided to upgrade my venturi's for better breathing at higher rpm. The venturi's that I have been running are 36mm and I have removed them and given them to poppy Penrose who has machined them out to 42mm.
I have measured the combustion chambers in the old heads to calculate the compression ratio as a guide for the new heads. Poppy Penrose has machined my 36mm venturi's out to 42mm and I have now reinstalled them. My manifolds have now been welded up so i can reface them and match port them to the heads.
Dean has made good progress with his engine over the past week . The cylinder heads have been machined after the new inserts were installed . The valve guides have been machined down for lift clearance , the guide bosses machined for dual springs and the combustion chambers reshaped to unshroud the larger valves and to increase chamber volume to gain the desired compression ratio .
Dean calculates a compression ratio of 10.1:1 and the cylinder heads are reassembled with all new Manley stainless steel valves , dual springs , chromoly retainers & hardened keepers . The heads are now also bored for the 103mm barrels
Dean assembles all of the cooling tin , Porsche fan and accessories onto his engine . He then fits the engine back into his bug and we manufacture new large diameter exhaust stubs and weld them to his extractor . A new 3" diameter muffler is used
Gday Wayne and Dean. Nice torque curve.
Those AMC heads, I've heard both good and bad about them of course, but I'm mainly interested in the casting quality.
Are they as dense in the casting as OEM, better, worse?
hypo-vwAustralias 1st 10sec street beetle (Jan 2007) 10.49secs@132m
modnrod wrote:Gday Wayne and Dean. Nice torque curve.
Those AMC heads, I've heard both good and bad about them of course, but I'm mainly interested in the casting quality.
Are they as dense in the casting as OEM, better, worse?
I too have heard good and bad reports about the AMC heads . When they were first produced a large quantity of them had inlet seats fall out . I believe this was due to insufficient interference fit when the seats were installed from the factory . They seemed to rectify this about 5 years ago . I use quite a few of these early heads for our performance upgrades as they save us buying brand new units , then stripping them and throwing away new seats , springs , valves etc . We can machine the heads and install larger seats with the correct interference fit .
I have found them to be of excellent quality casting and AMC have been very generous around the chambers . Just have a look at Deans pics and see how much material I have been able to machine from the chambers to unshroud the valves and increase chamber size to lower the compression for large capacity type-4 engines .
One thing I have found with them is , if you want to enlarge the exhaust ports and fabricate exhaust stubs from exhaust tube , welding is required around the exhaust flange area on the early oval port heads as the casting was a little thin at the heat exchanger sealing surface .
LIFE IN THE LOW LANE wrote:What size inlet and exhaust valves are you running now dean?
Dean is still running the same size valves as his original heads , 48mm inlet & 38mm exhaust , however we paid a lot more attention to flow in these heads which showed in his dyno figures , times on the track and how it behaves when driving . He is still driving his bug every day of the week , and I cant get him out of it !!
LIFE IN THE LOW LANE wrote:Cooling wise it runs the porsche cooling system. Are you running external coolers? What sort of cylinder head temps are you seeing running 10:1?
Sorry for all the questions but this engine is going to be somewhat Similar to what I'll have in my bus.
Cheers 🙂
Deans engine does run the 911 Porsche cooling fan assembly . The original oil cooler has been removed and by-passed , the oil flows through a single external oil cooler which is mounted in the floor of the rear cargo area (behind the rear seat) . We have cut a hole in the rear of the Porsche style fan housing and fitted a 2.5" diameter ducting hose from the fan housing - thru the firewall and onto the oil cooler sealing shroud .
We have fitted an electric cooling fan to the oil cooler , but Dean has never had to use it as the oil temp normally runs around 60 to 70degrees on a long run .
We dont have any cylinder head temp guages in Deans bug , but we know due to the porting , the style and design of the exhaust , the intake system and tune , that the engine / heads are running really cool due to the low oil temps recorded and that there is no pinging at all when under load .
