Another question re: blown engine build

[Charger4404spd]

Ok guys I removed the 906 heads from the engine just to check things out. Valves and seats dont look real good so I need to make a decision. I called the machine shop to get a round about cost to install new stainless valves, enlarge the ex. valves to 1.81's , do a 3 angle valve job and check the guides. Price somewhere between $800-$1000

I can get the new Eddy RPM heads ready to go from Aerohead for less than $1400. Now for the question. Are aluminum heads better for a blown motor? Any things to worry about? Or I can get a set of steel factory heads ready to go with the big valves for $600. Decisions decisions!!!

Also, I would be able to run the 84cc closed chamber Eddys and keep the compression where I need it.

OK guys, what would you do? All comments welcome.

[firefighter3931]

The price you quoted doesn't include the bowl cut/blend or the other hardware (springs/locks/retainers) so once you factor that in you'll be close to a set of Eddy RPM's. It adds up quick !

After all that you'll have heads that weigh a lot more and have way less flow. The RPM heads alone on a typical non boosted application are worth 80hp....with the forced induction that number widens significantly. Cylinder head flow = Horsepower......plain and simple. 

To me this is a no-brainer 



Ron

[Charger4404spd]

Thats what I was thinking Ron, I just want some reassurance, thanks!

[Charger4404spd]

Will the 84cc closed chamber heads be ok with the blower??

[firefighter3931]

Will the 84cc closed chamber heads be ok with the blower??

Sure, those will be fine. 

The reduced cylinder head weight will help offset the extra lbs that the blower will add to the nose of the car. It's a win/win all around. 

Oh, and the RPM heads come with hardened valve seats which are unleaded fuel friendly....something else that would need to be added to your iron heads. The reason your valves are sunk is because of UL pump gas.


Ron

[Charger4404spd]

Thanks man! Every time I turn around I find that the price keeps going up on this endeavor. I think it will be worth it in the end.

[firefighter3931]

Thanks man! Every time I turn around I find that the price keeps going up on this endeavor. I think it will be worth it in the end.

Of course it will be worth it....a Roots blower is very cool ! 

Here's a pic of the 671 on Kevin's Coronet 



Ron

[Charger4404spd]

Thats awesome! 

[Steve P.]

Damn, I LOVE that car.... 

I spy a 65' Coronet hard top behind it and in the next row too!!!!

[cdr]

Ok guys I removed the 906 heads from the engine just to check things out. Valves and seats dont look real good so I need to make a decision. I called the machine shop to get a round about cost to install new stainless valves, enlarge the ex. valves to 1.81's , do a 3 angle valve job and check the guides. Price somewhere between $800-$1000

I can get the new Eddy RPM heads ready to go from Aerohead for less than $1400. Now for the question. Are aluminum heads better for a blown motor? Any things to worry about? Or I can get a set of steel factory heads ready to go with the big valves for $600. Decisions decisions!!!

Also, I would be able to run the 84cc closed chamber Eddys and keep the compression where I need it.

OK guys, what would you do? All comments welcome.
                                                                                           

I heard that somewhere

[Chryco Psycho]

I agree use a newer set of heads , either the 84 or 88 cc heads would work fine as you can make up the compression with more boost . I would recommend using Cometic gaskets with the dis-similar metals between the heads & block .
The Cam design needs to have a 112 -114 cl to widen the lobe separation / overlap so you are not blowing good fuel into the exhaust system .

[Charger4404spd]

Engle recommended a 112.
As far as compression goes, according to the calculator, if I use a .051" head gasket with the 84cc heads that would put me at 8.45:1. Is that a bit too much? Could I go with a thicker cometic gasket?

[Rolling_Thunder]

The compression: you also need to take into account if you're using aluminum heads the 1 point of compression drop because of the aluminum. So your compression ratio will effectively act like 7.45:1    ---  At least that's my understanding

[Charger4404spd]

The compression: you also need to take into account if you're using aluminum heads the 1 point of compression drop because of the aluminum. So your compression ratio will effectively act like 7.45:1    ---  At least that's my understanding

Hmmm...learn something new every day. Not sure I understand that though. How exactly does it lower compression?

[b5blue]

It's an effect of greater heat transfer from the aluminum. 

[cdr]

 

[kamkuda]

How much boost are you planning?
You may need a better valve if you run a good amount of boost

I am planning around 10-15 lbs with a procharger and running about 8.5 compression with a coated piston.
Heavy Duty Valve in a Indy EZ head

FYI on Camshaft
Solid Roller
Cam on a 112
at 50 257 267
650 lift

Street Strip Car

[Charger4404spd]

How much boost are you planning?

6-8 lbs

[kamkuda]

You should be fine with the stock heads or have the valve coated if you want some added insurance
Sounds like a fun build.  

[Charger4404spd]

I have decided to get the RPM heads. I can get them almost as cheap as what the machinist wanted to redo the 906 heads.

Still trying to figure out the cam, some say 112° or 114°. 

[kamkuda]

Both 112 and 114 will work.
A cam recommendation comes from all factors including cu, air flow, intended use, boost etc/

I would call dwayne porter Porter Racing Heads and have him get you a custom grind.

[Charger4404spd]

I will give him a call tomorrow, thanks!

[Steve P.]

You may want to consider getting the heads from Dwayne too. 

[firefighter3931]

You may want to consider getting the heads from Dwayne too. 

  Or at least have him inspect/prep them 

PRH 802-951-1955



Ron

[Charger4404spd]

I called Dwayne today. Real nice guy and he took the time to explain some things to me. Sounds like he really knows his stuff. Look like I will be ordering a set of RPM heads from him and he is going to blend the bowls, do some work on the valves and set the spring pressures as well as working on the valve guides so they will work better with a blown engine. The price he gave seems really fair considering all this work he will do to them