New heads?

[mojavered]

Alright, we were going to put some new Eddy RPM's on my engine, but when my engine guy put them on the flow bench, he was pretty dissapointed with the numbers that they claim vs what they were.  Then someone had a set of Victors for cheap, but you need offsest rockers and there may be a lot of time involved to make them work.  So now the question is, what head should I get?  I am thinking of the Indy EZ head and the Stealth head.  I know you get what you pay for, but how much better are the EZ heads than the Stealth heads?  Or are they?  Any thoughts? 

[73Chally]

Not real sure how they compare performance-wise, but I've heard some good things about the 440Source heads.

[The Cuda Guy]

Not real sure how they compare performance-wise, but I've heard some good things about the 440Source heads.

Yes I agree, but do the research on it.  You need to make some adjustments on a few things.  Get with Stroker he has the info.

Don

[Oldschool]

What all is done to your engine?  Unless you are building a sho nuff hi-po engine, I wouldn't worry about flow number all that much.  A common mistake when building a street engine is the old "more = better" cliche'.  High flow heads hurt more than help if you don't do one of two things to accomodate the higher flow capability of the heads.  The bottom end needs to move enough air to take advantage of the higher flow.

1) --  if stock, or near stock CI, then you need to up the rpm range the engine operates.

OR

2) --  build more CI into the bottom end. EG a stroker/ big-bore engine.

Big money builds do both.  Build a big inch motor that revs.

If you have a relatively stock bottom end, it can't move the air required by the heads and this results in worse then stock performance.  Especially in the lower rpm range.
Just my     

[moper]

Flowneches are simply tools. Differences in the weather, the particular bench, the location of the bench, and the correction factors make repeat numbers difficult to get. Add to that the fact that published flow numbers are ALWAYS at least a little optomistic. So knowing that... how bad were they? All aftermarket heads should have the valve job redone, and a good valve job can add tens of cfm to an otherwise good port. What are your plans for the engine and car?

[71chally416]

 

I think of a flow bench like a chassis dyno. It's good for comparisons but not for absolute numbers because of the variables. Stock head > Modified head on the same day is a valid test. Testing just for CFM is not.

[mojavered]

Thanks for the info so far.  It probably would have been a good idea to mention that it is going into a 70 block .30 over.  Forged crank and rods with new flat top pistons.  496" And an ending compression of 9.5:1. 
I wll get a hold of my builder, but he said that he had a stealth head out of the box that flowed bettter than the eddy rpm head, just not sure of the numbers.  He was just very dissapointed in them.

[Oldschool]

My buddy has a 496 in a Dart.   It has 10.5 pistons and a forged bottom end.  He is running a Lunati Voodoo hydraulic cam.  He is running an Edelbrock super victor with a 1050 Dominator.  This induction system is sitting on out of the box RPMs.  TTi headers into 3" exhaust.  It weighs 3450 with the driver and runs 10.95 @ 121.  That translates to about 550 hp give or take.  It went from 11.7x @ 115 down to the 10's by changing out the six-pak induction system.  It is a street car that sees the track once or twice a year.  He might run faster with the Indy EZ's or Stealths, but he could probably get the Eddies ported and meet the same goal.  I think it runs great for box stock heads......