ANYONE know about my heads 906 and ProMaxx

[Gene chiodo]

Hello guys I have two sets of heads a new set of the Promaxx as cast(CNC now available) and A really nice set of just done 906s with newly done full port and polish. MAN O MAN do they look good!, milled 040 to bring chambers to 79cc.Llite weight valves Ferrea,120lb springs,new pc seals good to 560-580 lift. They said they flow 280-290 at 550 lift. Exhaust looks better Must be over 200 flow. Now you head guys,which do u think will make more power?I kinda want to use the 906s as might street race this thing no and then. Also ready to buy pistons to go with my 6.535 manley rods. I have a 470/ 400 block. Only piston to go with my set up is 1) ICON 499$ too heavy 850 gms with pins. Next 2)440 source 599$ 770 gms and Last and Best 3) ROSS 649$ 740gms forget the icons 9.2 compression, 440's are 9.9 comp and Ross 10.8 comp all with 80cc with 024. shim gaskets. I'm thinking of getting the Ross and using 051 gaskets to lower the comp to around 10.5-6 but is that too HIGH for 93 High Test gas,even if I back off the timing a little?Because I think the 906s are what I want to use if they perfom as well as the ProMaxx.I know the alumin can take up to 11-1so why I'm askin. And what u guys thinking of E85? Camwise was thinking of Bigger HYD. flat tappet XE294 251/256 duration @050 525/525 lift maybe bleed down the cranking pressure below 200 ? IS cam too big?I know that a hyd 250 dur is about 10 degress bigger than a 250dur Solid cam SOOOOO? also LOVE LUNATI not really impressed with Comp Cams but that cam seems NICE! Maybe have lunati make one for the engine? Don't want any more than 600hp, don't trust the block any higher . it ain't a 230 its a 530 block. WHAT DO U THINK OUT THERE!!!! Last question will the power I gain by the higher compression,be lost by running less timing? Know its not much but 10.5 instead of 9.8 will be 10-12 hp but 2-3 degrees of timing might be MORE? Do I think too much!!!!

 

[69hemibeep]

If you were going to a lower compression I'd say the 906 heads all the money is in them already.

 

[Coyote]

IMO, the work on the 906's sounds great, I would not hesitate on a race motor or where you could put race gas in on occasion and keep some remnants in the tank. 10.5 is pushing it, the pumps say 93, but what about the load of kerosene in the tanker before the 93 or the diesel fuel remnants? Several forced induction guys on Dragweek use E85. They seem to have the cars tuned for it and run great on the road and track both. I don't think you have any choice but the Ross pistons.

If you want to throw about a thousand bucks at the Promaxx, KG Engines in Kansas, OH just CNC'd my 440 Stealth heads. Very NICE, exquisite chambers and impressive ports both ways! That would certainly cover you to 11:1 or maybe a little more.

I'd call the cam grinders tech lines and get their opinions. They are the "experts". There is nothing like a pro in any line of work and they do it every day. My opinions, GOOD LUCK!

 

[quikbird]

If you are pushing 600hp you might think about a stud girdle for the block. What is the lobe separation angle on your cam?
I am sitting at about 10.5 comp ratio and have not had any problems with pump gas. Lightest weight of rotating assembly is better, and balance it!
Last question, yes you will lose power by pulling timing out.

 

[Coyote]

If you are pushing 600hp you might think about a stud girdle for the block. What is the lobe separation angle on your cam?
I am sitting at about 10.5 comp ratio and have not had any problems with pump gas. Lightest weight of rotating assembly is better, and balance it!
Last question, yes you will lose power by pulling timing out.

Right, with aluminum heads you can push at least a half to a point MORE than you can with cast iron. The aluminum rejects heat better. 10.5 with cast iron IMO is very froghair close to serious hurt things issues. Stud girdle sure wouldn't hurt, sealing them can be an issue.

 

[Gene chiodo]

ALL You Guys are great want to thank you Made me feel good about the 906's and can probably use a 051 composite head gasket,instead of 024 shim to gain 6-7cc's on the chambers plus if I can hear over the exhaust any marbles,I could switch to E-85 and will just swap carbs and fuel pumps right? Have new question coming out if u guys can help me with that all will be appreciated..........Gene C