"now have found a combination that the exhaust flows 185 CFM with the velocity increased from a miserable 390 to an impressive 566 FPS! That is a 45% increase in velocity with only a 3% loss in flow rate!"

For those that have the cylinder head with the high velocity exhaust option... have you noticed any "real" improvements or changed dyno charts?

thx,
-S

 

I believe you're talking about their"4 inch exhaust" is that correct?

 

nope it's a bit of head work they do. shouldn't the intake and exhaust ports already be like mirrors with a good port and polish? i wonder what they do for their high velocity exhaust option.

 

How do you get mirror finish on the
ceramic liners ?

 

it was just a figure of speech

 

Jake check this old thread out. It will probably give you a lot of good and crappy info. Try to notice the good info...lol. I found it pretty interesting. You might also searc for the flame propogation thread afterwards. The gist of these is that the 951 head flows enough, in stock form, for a 3.6 ltr application, therefore the "porting polishing craze" is about vendors stealing money. I have yet to see ANY dyno sheet that shows the direct correlation between their head work and hp #s. That doesn't mean they aren't out there, but I have searched this a lot, and still haven't seen a clean swap comparo. Here's the thread title. Should I Port/Polish My 951 Head? just do a search under Port/Polish and it'll be right under your threaad here. Good luck
E

 

Within few weeks, you will get the before and after data for a cyl. head SpecialTool is getting.

 

Another mis-conception is about how much HP/TQ you gain from P&P; Various other tuners do P&P work, they post flow numbers and % increase in flow. A LOT, if not ALL, of rennlisters love those vendors. Now, when it comes to be more specific (such as LR for EXAMPLE) they do not have HP numbers, but flow and % gained.

It is going to be really hard to dertermin just how much HP you gain from P&P, it all depends various factors such as condition of the engine, turbocharger, exhaust system (the whole thing), extent of P&P, timing, tuning.....the list goes on. That is probably the main reason why no power charts are released, but flow numbers instead.

 

[QUOTE=hosrom_951
It is going to be really hard to dertermin just how much HP you gain from P&P, it all depends various factors such as condition of the engine, turbocharger, exhaust system (the whole thing), extent of P&P, timing, tuning.....the list goes on. That is probably the main reason why no power charts are released, but flow numbers instead.[/QUOTE]

A simple before and after dyno with head change only, on the same car would give a reasonable comparison.

 

I am going to change absolutely nothing but the head between today and 2 weeks from today. We will have good numbers.

 

special tool... is that the 16 valve head?

 

David: Well, that's one way. But even with a bone stock car with a MAF, the condition of the engine would also effect the numbers........

Vendors "play it safe" and use the flow charts instead

 

Pat - not yet. 3 heads.

 

Sorry...

Special Tool, Location: in my garage, drilling out 951 pp bolts

I am at that point also, what are you using ?

 

"Within few weeks, you will get the before and after data for a cyl. head SpecialTool is getting."


Drool!

Hos...now how would it not compare almost exactly, if Special tool were to dyno sometime like, oh, today, change nothing, and dyno again in two weeks. Anything above a couple horse power/torque would stand out like a sore rectum. Cripes... how much more do you need? BTW there is a conspicuous absense of other vendors telling you about new products AND promising verifiable numbers...unless you think Special Tool and John are lying about the stellar performance on his dyno sheet? You wouldn't do that would ya?


Can't wait for the head job...err a...new head.