300hp C1 head finished..

[xrglen]

i have finished my 300hp C1 head at last.. i removed it a few weeks ago and did a few more cheap tricks to it and it should be back on soon.. as said before, it has 1.84" inlet valves and just over standard, 1.56" exhaust valves.. it has no porting on the exhaust side, just a good bowl and seat job to get flow up in the low lift areas only.. the inlet however got the same as the exhaust as well as mild porting around the valve guide bosses which required the bosses to be removed and while they were out i put them on the belt sander and gave them a 12mm or 1/2" tapper on the section that protrudes into the port..i also made the bowl area below the seat 88% of the width of the valve on both the inlet and exhaust.. lastly i did some more releivivg around the inlet swirl lip in the chamber.. i had already cut the section back but now i rounded the edge and blended it for better flow.. im aiming to get each inlet port to flow the same as the aussiespeed 2 barrel inlet which flows around 212cfm per port.. the head will be flowed soon and figures will be listed here.. comp will now be 10.8:1 as my block has already been decked a few years ago when used for another car so 10.8:1 it is...
all this along with my new 650cfm 2 barrel holley should get me very close to the magic 300hp number... stay tuned....cheers

[81foxdwagon]

Sweet. Im writing down all these tips for my N/A crossflow build.

[xcsam]

Sweet. Im writing down all these tips for my N/A crossflow build.

Me too! I will soon have a 250 crossy sitting around gathering dust and I would be very keen to learn more about building a tough crossflow!

[matt_lamb_160]

i also made the bowl area below the seat 88% of the width of the valve on both the inlet and exhaust

What is the 88% is that some sort of optimum which all heads should have?

[xrglen]

What is the 88% is that some sort of optimum which all heads should have?

hi, yes it pretty much is the perfect ratio.. if you get a std head and work this formular, along with 2 simple inlet valve mods, 1 is face cutting the valve and 2 is back cutting the valve, you can get great gains in air flow and still keep excellent air speed.. cheers

[XFpanel]

Is this the head you're offering in the second 300hp kit?

[xrglen]

Is this the head you're offering in the second 300hp kit?

hi, yes thats correct.... cheers

[crazykrispy]

would u happen to have a before pic?

[xrglen]

would u happen to have a before pic?

hi, i will have on friday or manday as i have another stock C1 head comming from Adelaide.. cheers

[lowxdute]

So would the head flow say 320hp?
ZAC

[xrglen]

So would the head flow say 320hp?
ZAC

hi, it should flow about 310hp but with a bigger cam it could make 350hp if the motor runs at 112% volumetric efficency.. thats how i made 340hp from a head that flowed 290hp 10 years ago... many mild motors run at over 100% efficency.... cheers

[bop]

nice work xr glen, have you experimented with LPG on crossflows before, im in the middle of converting mine. Im planning to use an Xe efi inlet manifold, ive welded up and smoothed the EGR valve port and the injector holes. Not sure which converter & mixer to use, either Gas research/B2 converter or Parnell Mixer ring/C5 converter or maybe an impco 225 set up. Any advice

[xrglen]

nice work xr glen, have you experimented with LPG on crossflows before, im in the middle of converting mine. Im planning to use an Xe efi inlet manifold, ive welded up and smoothed the EGR valve port and the injector holes. Not sure which converter & mixer to use, either Gas research/B2 converter or Parnell Mixer ring/C5 converter or maybe an impco 225 set up. Any advice

hi Bop, welcome.. i have been asked this many times in the last 2 years.. the only way LPG can give good performance is by using a turbo.. the old EFI inlet systems are ok at best but for any kind of N/A performance you need good old petrol.. the best n/a lpg system will only give performance levels just above a standard petrol motor.. stick with petrol or stick a turbo on it....cheers

[lowxdute]

Hey bop if you want a decent cfm gas system for 250xflow- I'm going the impco 425mixer (they flow 460cfm and many 351clevos use em) which bolts to a squarebore holley base plate. Im using the 465baseplate (or a 390/450 they're the same too if squarebore that is) to improve airspeed/torque as the 600+ baseplate is very big for a stock/mild xflow. A good convertor to suit and atleast it'll flow a **** load better than a gas ring over the little weber! Biggest cam for gas if you got auto/powersteer/aircon is the crow 14892 )1800-4800rpm quoted range). Im ripping fuel tank out and fitting a massive 110L/90L useable tank in boot too. Anyway back to your head thread glen ta,
ZAC

[XF Freak]

excellent work once again glen head looks a treat

[xfute]

seen it in the flesh today it looks grate

[lowxdute]

When this all getting dyno'd and your gunna do it rwkw through the lightened xe still with 3.5diff and T5 glen? 300hp would be around 175rwkw with a T5 manual aye glen?
ZAC

[BigBam85]

seen it in the flesh today it looks grate

im jealous

[xrglen]

When this all getting dyno'd and your gunna do it rwkw through the lightened xe still with 3.5diff and T5 glen? 300hp would be around 175rwkw with a T5 manual aye glen?
ZAC

hi Zac, im going to use a chassis dyno so all figures will be in rwkw or hp.. i have a 3.7 and 3.5 diff to use for the drags and the 500 and 650 holley just to make a comparison.. yes im using a T5 and i have 5 spare boxes as i plan on breaking a few..lol.. i need to get the XE spac down to 1180kg but with no spare, p/s or a/c i think i can do it.. i have had a XE at 1265kg but now i will have a 10kg lighter T5 gearbox, alloy tailshaft, weld draglite rims and a few other tricks up my sleeve...the car is getting painted next month and will be ready for racing in sep-oct....cheers

[lowxdute]

1180kg sweet. Thats just lighter than my old TE sedan! What about removing the bumpers and a headlight for a C.A.I. spot haha, save a few more kgs. Apparently somer of the speedway guys used to run 1/2 dextron 3/half regular diff oil to gain about 3 or 4rwkw on the xflows and they werent wrecking the diffs. Good thing the T5 runs full atf anyway. Also 10w30 is a bit lighter than 20w/50hehe. This 300hp xflow will it run 10w/30 or can u go even thinner?
ZAC

[xrglen]

here is a std C1 and C2 head as promised...cheers

[matt_lamb_160]

Do you have flow figures for the std. C2, I have your figures for the C1A

standard C1A head std valves
100", 200" , 300" , 400" , 500", 550"
inlet
57 , 98 , 136 , 170, 196 , 200, 1.78"in
exhaust
49 , 84 , 113, 137 , 152 , 159, 1.54"ex all figures are at 32"
to convert to 28" divide by .935

But not the C2.

[xrglen]

Do you have flow figures for the std. C2, I have your figures for the C1A



But not the C2.

hi, i dont have the sheets here but from memory the C2 head flows 1.5-2cfm less than the C1 head only at 100", 200" and 300" due to the shrouding around both valves but at 400" and 500" they are the same flow.. they flow the same when you spend 1 hour with a die grinder, de-shrouding the valves...cheers

[matt_lamb_160]

I was just thinking to improve the inlet to exhaust ratios below 0.4 (0.1-0.3), ~ 85% av. for the C1, you may be able to use the C2 instead without as much work around the exhaust valves.

[xrglen]

I was just thinking to improve the poor inlet to exhaust ratios below 0.4 (0.1-0.3), ~ 85% av. for the C1, you may be able to use the C2 instead without as much work around the exhaust valves.

this is where the physics comes in.. all motors will excellerate quick if you have good low lift exhaust flow.. eg the perfect motor would have 80% of its exhaust valve lift in when the piston hits bdc or 68% of its maxium exhaust cfm flow by bdc.. you can never get both from my experience but the low lift area if very important.. its the high lift figures that can stuff everything up.. with my new 365hp C2 head, i have upto 15% more low lift cfm than a standard head but only 5% more at high lift on the exhaust ....
it flows 238cfm@550" lift on the inlet and 167cfm@550" lift on the exhaust.. now this is under exhausted at a 68% ratio but when the inlet which flows 224cfm@550" lift is fitted, it comes to the perfect 77% inet to exhaust ratio..