Manifold Comparison

Great information Jim.....that you for posting it !!!!!!!

I know you have embraced the idea of The Dominator/Torker for a long time....... and for a smaller volume head I think you are correct. I don't even think that a torker could be match ported to my SR heads without adding a lot of weld on the ouside of the torker s runners ?

My gut tells me it is not enough intake manifold to feed a 260 cc intake runner SR head @7500 rpm ??? Not enough runner/plenum volume is my gut instinct but I have NO proof to back up that assumption!

But....I have been wrong many times......and I want to learn more than I know now.

Please continue to educate me !

Thanks,

Rob

The Indy SR heads keep the dogleg style exhaust port..... good for street ie: no custom headers....but are what I would consider a medium cubic inch capable race level head with work. There is enough meat in their cores to get them to get 260cc intake port runners which is a very good combination for a 401 or 426 and 434 stroker in a high horsepower street trim or all out race engine at that cubic inch level.

They are flow limited mostly by the size of the valves. There is no valve spacing to go past a 2.125/1.65 valves so additional port volume past 260 cc is counter intuitive. To get the full 260cc volume you must move the pushrods over and use offset rocker arms as well as raise the port height considerably.

If you may ever want to push past the 750 HP level NA go with the larger Indy -1 race head right off the bat.

I don't have my flow sheets at work with me.

Off the top of my head Intake at .500 valve lift 305 cfm,  at .750 lift 345 cfm,  .800 lift about 350cfm and stagnant or losing a after that. The exhaust generally in the 245 range. A litle bit more than 2/3 intake of intake flow.

The cfm numbers probably are not as important as having the correct port volume for the cubic inches you are running.

But it is a lot of work. Buy a set of the -1 heads with either the 260cc or 300cc port volume depending on the cubic inch you are running. I wish I would have I could have saved money. At the time I bought the SR's back in 2004 I thought I was just building a hot street car not an race car.