What is the dynamic compression ratio based on your new cams and 11:1 static ratio?

Are you building for more hp at high rpm or max torque at driving rpm?

 

Haven't looked at the dynamic compression yet but I'm not too worried. Overall I expect more power from the engine though the entire factory rpm range, I should see most of my gains from 4700-5100 due to the increased head flow and cam duration. I think torque will be great

 

Rods and Pistons are balanced to the best of my ability, Small end within .1-.4 grams, Big ends are within .1 gram and overall weight is within .3 grams. Cranks out for nitriding and block is setup in the surface machine.

 

So our cranks are forged and induction hardened.
Why are you nitride treating it?

Did you shave over .030 off journels?

 

I dont think even .030 would get through the hardening but this crank was in a service truck that spun the rod bearings on the corresponding journals and softened them somewhat, Standard Rockwell for the other 8 are about 60, these two tested 40-45, Plus a little insurance always helps,

Ideally I would actually prefer getting a billet crank made since the rods are good for 1000hp and if I decide I want turbos I can swap to forged pistons and actually push to the breaking point of a stock crank.

 

Dymanic compression looks to be about 10.60 which is pretty good.

 

Are you sure?
That's pretty high, you using race gas? I guess water meth will help but you will need lots of it.

Could you estimate the block machining costs? New OEM bare blocks are about $850 so I would like to see which path is more economical.

 

No it should be fine, Running factory compression with a KB or Whipple produces more dynamic and more effective compression then 11:1 so I'm not worried, especially with how I'm doing the valve job

Prices I believe if you want it baked and pinged are $100.
Bore and hone are $275
Surface $225
Alinge hone $250

Most OEM blocks are not alone honed just Aline bored. That quote might be a little high aswell.

 

Got the block honed out and all done, Time to get back on the heads and headers.

 

I would be very intrested in seeing your cam specifications. I know those puppies are expensive and like to know what they are.

My supercharged V10 can push 12 psi at wot. It rarely does. Typical load pushes between 5 and 7 psi. PCM doesn't go into open loop until cylinders are 100% full volumetricly which is at about 9 or 10 psi. Efficency governs dynamic ratio. Basically when intake and exhaust valve close and air cannot excape out of exhaust valve while piston is coming up. So a supercharged motor has variable dynamic compression ratios.

At sea level a dynamic ratio above 9:1 will cause issues with pump gas. The camshaft on 11:1 motors will hold exhaust valve open a little longer to reduce dynamic ratio to a usable figure.....based on fuel used. IE race gas, alky, pump gas, E85, methanol etc as they can take different dynamic ratios.

11:1 dynamic is almost above E85/alky/methanol range so I hope your not there unless that's your fuel choice.

I suspect your cams were sized per your input and hopefully bleed off some to allow pump gas??

A high compression motor is more versitle than a low compression motor. Example: 8:1 static compression motor can NEVER get above 8:1 dynamic reguardless of cam used. An 11:1 static motor can have dynamic ratios up to 11:1. So you can build a 9:1 dynamic for pump fuel. Or a 10:1 dynamic for alky, or even a 11:1 dynamic for methanol.

IS ALL ABOUT THE CAMSHAFT.

 

Now, porting the heads.

For HP you cannot bypass this step. The more they flow the more power a motor will make. This will however move the peak torque to a higher rpm. Probably 3600 rpm instead of 3200 rpm. This is because porting will slow airflow at lower rpm. More rpm increases air speed and cylinder fill causing peak torque and hp at a higher rpm.

Your problem is you will have heads built for higher rpm hp and torque, but your intake manifold will act like a Nascar restrictor plate. So air will flow fast thru intake than hit heads and slow down.

I suspect you will have to address the intake restriction. These intakes are designed for torque not necessarily hp.

 

Im not sure how the intake will act with ported heads, But im very interested to see. As for porting the heads the stock ones are so damn restrictive i should keep all the low end torque i had stock no matter how much i hog them out unless i do something wrong to seriously hurt the velocity like sharpen the short side radius but i dont tow much and it doesnt bother me to see peak come in 600rpm higher then stock since these engines love to rev anyway. This engine has very similar CI per cylinder as a 350 chevy and the stock port flow is horrible at 160cfm max on the intake.

As for cams i have not yet designed and produced a custom grind cam but im working on it. Im using a stock reground pair with 10 degrees more duration on the intake and exhaust so it probably wont bleed off much more then stock. Also after decking the block and heads and installing the stainless valves its looking like compression will fall closer to 11.5:1. Might need to do a race fuel mix with 91 but the modular engines are pretty good at making compression work.

 

I can't wait to see how it runs.

Overhead cams and shaved heads and block, I guess I assumed you would be using a thicker head gasket to compensate for loss material. Won't timing be off a tad due to distance from crank to cams?

More compression due to shaved heads and block implies standard head gasket?

Thicker v10 head gaskets are probably hard to come by though.

 

Id have to call Cometic and have them make me some but im not worried about that. Hydraulic chain tensioner will make up for the change. I only took off about .015 combined per side and maybe .003 from aline hoing and moving the crank up

 

Ok, but it's something to think about when you spec your cam.

In order to tighten slack on both sides of cam sprocket the sprocket will have to turn a tad....more than stock. Leaving all slack on tensioner side of chains.

I don't know if that will advance or retard timing but it can be addressed in the cam regrind I think.

Worst case would be a couple degrees advanced on one bank and a couple degrees retarded on the other bank.

I would vote for thicker head gaskets .....but that's just me.