ChrisE wrote:
Rules for this exercise - no efi, no turbo, budget needs to be reasonable
We are thinking the 4g54 + Tr magna head, plus the usual balance shafts/flywheel.
What sort of cam would you guys run?
Head work? What compression? Pistons?
Oil work considering the flogging these engines get?
Recommend a machine shop around brisbane/SE QLD to do the machining?
I will try to give you a run down on my race engine -- Its been very good for hillclimb and circuit work
I beleve you almost cant get to much weight out on the rotating parts on an astron
I only build the small bell housing pattern 2.6 so I can run the smaller 2 lt size flywheel
I make my own flywheels from 4140 steel so I can get them under 5 kg and the outter edges are milled to make the outter edge as light as possable
http://www.sigma-galant.com/viewtopic.p ... eel#p24148
my flywheel is lighter than the one in this old post
and I have a compete clutch assembly that weighs 2.3 kg
I have removed 2 kg from the crank shaft with some polishing and knife edging
the rods are still astron however the bolts are now ARP the beams have been polished and peened
balance shafts are gone of cause
and the crank pulley is an undersize aluminium pulley
I run a bored block up 0.60"
of cause there was a lot of care ballancing and assembling the bottom end
the top end has a little port work nothing special I just knocked the guides out and ground the lumps out around the roof of the port
tthem machined the guides down where they go into the port with a taper to cut down there shape
the valve were back cut and the seats were cut right to the edge of the valve
the cam I run was a Speco gride ( MS 344 ) inlet spec 45/71 ex 85/45 duration @ 050" 267 and valve lift 471"
the comp was set at 11.3:1 and it was happy to run 30 deg total advance with 98 oct fuel
twin DCOE13 webers with 41 mm chokes ( I had to machine my own chokes weber dont make them this size )
I made my own headers a 4 into 1 with 1 3/4 tube ( sorry cant remember the primary tube lenth )
I fitted a larger baffed sump with a crank scraper
the engine made 119.5 Kw at the treads ( @ 6100 rpm ) some time ago
and spins 7000+ in all gears without much trouble