Iron vs aluminum heads
 

Ok I have a set of max ported 6x -4 heads on my turbo 455 motor roughly 9.5 to 1 compression would I see any gains / benefits by going to a max ported aluminum D port head , besides the xtra compression ? Also are the size of aluminum heads exactly the same size as iron heads , because I am very tight with my log manifold to the frame now ..and all my hot air crossover pipes were mocked up with the iron heads . Thanks

Dimensionally the heads are the same so no issues there.

Thanks B man

You currently run your setup on E85, is that correct?

With conservative levels of boost, I think raising the compression slightly may be beneficial as part of a change to an aluminum D port. As far as a max effort port goes, hopefully somebody more knowledgeable will chime in. My understanding is that you're changing the pressure ratios slightly. The better ports on the aftermarket head would theoretically create a situation where 10 lbs of boost is actually more airflow, which would create more power.

Richard Holdener has been able to prove pretty positively that the higher base hp your engine makes normally aspirated, the more power you'll make at given boost pressures, with 1 bar being roughly equivalent to a doubling of power.

A true 310cfm port D headed 455 should make 550hp without too much trouble. 14.7psi should theoretically get you to around 1100 assuming the turbo sizing can offer enough flor to support that power level.

Is this a race only application? If it is, u can go much higher on compression ratio... I was running 12to1 with 42lbs of boost on alcohol..
It's all a matter of tune and how far u want to push it. Race only....push it!

As far as aluminum aftermarket heads, they will flow better out the box with room to grow...

Thanks guys , the only reason for charging heads is that my max ported iron 6x heads are leaking water somewhere as I am losing water from my radiator and there is no water in the oil . I see water or condensation from the exhaust but it’s deceiving because I run E 85 and it attracts water , so I think I must have a pin hole leak in the intake or exhaust port somewhere . It does not effect how the motor runs but it bothers me so although it’s a lot of work I have to pull the heads and see if they can be epoxy repaired or buy aluminium ,,,, are edelbrock D port still the favorite or Kre ?

I would go kre d ports... are you building pressure in you water system? Are u sure it's not a small Crack in a cylinder? I have had that issue on a nitrous car... very small Crack in a cylinder and it was pushing pressure to the cooling system.
You will have more cylinder pressure than cooling pressure.. cooling systems are only around 13-15psi... any oil in the water?

i would think either would be acceptable. hopefully you find the leak.

Either will do but I think the KRE is a bit better from what I have seen... you don't know how much it pains me to say that though as I dislike KRE...lol

I’ve been happy with my KRE D ports.

That said the first thing you might try is a cooling system sealer. You can get the AC Delco tablets that GM uses for about 5 bucks

If it’s a casting porosity issue, that might be a quick, cheap fix.

Cool I will give them a try. , thanks

Thanks No oil in water .would I see air bubbles in the radiator if the cylinder had a crack ??

Also could water be escaping the head gaskets somewhere ? I am running the cometic gaskets ..

are you running antifreeze?do you have a over flow on it?if your running antifreeze and its steaming from the exhaust you can smell it. if compression is leaking in the coolant system. it would build pressure in the radiator and push past the cap. hope this helps. good luck

I have a over flow bottle and it’s empty that what made me check the radiator level and it was a little low 1/2 quart . I run a rust inhibitors and 25 % antifreeze with distilled water . Don’t really smell anything from exhaust but E85 has its own smell , I guess it could be leaking into the intake side as well right ? It’s got to be a tiny pinhole somewhere . No water anywhere on the motor or floor after sitting or after a drive …

Have you checked your plugs as well? If you're washing water through the combustion process, you'll steam clean the cylinders effected. The plugs will look incredibly clean when you pull them out. If you pull them and you have one or two that are clean compared to the others, look for the possible issue there.

I have a good idea how much, I remember all that crap way back!! I took a good hit as well$$$

you could pressure check the coolant system. maybe find it. how often do you have to refill?

I already pressure checked and it holds the same pressure for 45 minutes , I don’t drive the car much especially in the summer too damm hot but I add maybe a quart , after 2 driving outings … I retorqued the heads , pulled plugs and they all look the same clean (thanks E85) so maybe a head porting guru knows if it’s common for a max ported 6x -4 head to develop a pin hole and could it be leaking into a intake or exhaust port ? I am not seeing any I’ll effects in the way the engine runs .. i guess the only way to really find out is to pull the heads major job with a turbo , or live with it .. going to try the GM tablets to see if that helps as suggested …