Forced induction and flow...

[Robert Lone]

(I'll begin by saying that the answer to my question is almost certainly yes.)

I have spent many years building heads for race applications. Opening up the pockets, unshrowding the valves in the chamber, blending where the cutter stopped making sure not to cut all of the short turn out of the runner, grinding 3, 4, 5, or even 6 angles on the valves, and getting the 45 out there on the ragged edge of the valve. All for the purpose of maximum flow, and in turn horsepower. I understand that "every little bit" helps even if the gains are minute. All of this was on naturally asperated engines.

Now my question...

With a turbo, you can pretty much build enogh boost to send the crank right out the oil pan. If that much fuel/air can be stuffed into the cylinder, then is all of the porting, polishing, 3 angling, and everything really worth the 100's of hours or 1000's of $? What are the gains? Is the difference noticable?

Another DAQ,

Robert :tup:

 

[MikeRenz]

Re: Forced induction and flow...

it always comes down to CFMs and path/flow of the air. Compressed air still takes advantage of these things. You stand to gain more for a NA motor....but who doesn't want the most free-flowing motor possible?

 

[warmpancakes]

Re: Forced induction and flow...

The exhaust side doesnt matter as much as a NA car because you lose velosity, the intake side it helps but to a point you can actually affect the efficency of the turbo.

 

[MikeRenz]

Re: Forced induction and flow...

The exhaust side doesnt matter as much as a NA car because you lose velosity, the intake side it helps but to a point you can actually affect the efficency of the turbo.

well...you don't affect the efficiency of the turbo, but affect which turbo you should choose based on its efficiency/volume map. Or is that what you're saying?

 

[warmpancakes]

Re: Forced induction and flow...

Yea thats what I meant

 

[Don W.]

Re: Forced induction and flow...

I wonder if this:

http://mototuneusa.com/think_fast.htm

would apply?

I got this from a thread here on break-in. He has some interesting idea's here also.

I also seem to remember a porting theory where a "venturi" was used just inside the valve seat to, in effect, bend the flow around the seat and out through the gap between the open valve and its seat. Did that make sense?

Just my:2cents:

 

[Robert Lone]

Re: Forced induction and flow...

Like the venturi in the late 80's Chevy truck heads? They had that massive screw ramp under the intake valve. It was there to make the engine have more tourqe but it just made me cringe. The thing was like 25cc or something!

Robert

 

[It's just a six]

Re: Forced induction and flow...

Anything you can do to improve airflow will help when turbocharged or blown. When the heads flow much more than stock..... the boost pressure will drop.... but.... you will make more HP. :tup:

 

[Robert Lone]

Re: Forced induction and flow...

Thanks for all of the posts guys.

Robert

 

[dgoodhue]

Re: Forced induction and flow...

My thoughts on head flow and forced induction.

Turbo can make up for a lot of deficiencies in air flow (look at our stock heads). That being said additional air flow does help but the gains aren't as dramatic as in N/A applications where the heads are one of the biggest key in making HP. IMO using a good set of heads is very helpful especially if the are more knock restistant like vortec's, but you will get dimminishing returns with a good porting job vs an all out race maximum flow porting.

Ed Hess went 9.9's with unported Vortec's. One factor is what is your goals for the truck, if you want an all out bowtie block SyTy that is will challenge for the title of the fastest, you probably want to go all out on the head work. If you want just another 11 sec truck, it probably doesn't require the biggest buget for heads...

 

[Robert Lone]

Re: Forced induction and flow...

I can only assume that getting the little bit extra in flow is the same reason for the merge collectors in the headers like I've seen here.

Robert

 

[It's just a six]

Re: Forced induction and flow...

I don't think that Ed Hess that went 9.9's could have done that time w/stock original unported heads?
But..... theres always nitromethane

 

[ed hess]

Re: Forced induction and flow...

I don't think that Ed Hess that went 9.9's could have done that time w/stock original unported heads?
But..... theres always nitromethane

wanna bet?

they werent port matched or ported for max velocity and flow at the time we ran a 9.93 on them.

only thing that had been doen was clean up the mistakes made by the person that originally had done them.

fwiw it wasnt the stock heads that made it run but the combination and the tuner.

ed

 

[It's just a six]

Re: Forced induction and flow...

(only thing that had been doen was clean up the mistakes made by the person that originally had done them. )
So ...sounds like there was something done to the heads. they were not completely stock??
I'm sure Hoovers Heads are all stock also. :2cents: :2cents:

 

[ed hess]

Re: Forced induction and flow...

(only thing that had been doen was clean up the mistakes made by the person that originally had done them. )
So ...sounds like there was something done to the heads. they were not completely stock??
I'm sure Hoovers Heads are all stock also. :2cents: :2cents:

no they werent completely stock.

when i got them the valve guides were so bad the valves literally wiggled in them. and like i said we had to correct a lot of mistakes. the lower intake i got with them had the vortec mod done to them but the guy had cut thru the injector seats so that fuel would push out of the injector bung during boost. a real fire hazard. the welds from the vortec mod looked like 1/2 inch bead as if a begginner had done the mod.

otherwise the heads had no other work done.

 

[It's just a six]

Re: Forced induction and flow...

What are all the sparks from the photo?
Have you tried to run a set of great flowing aftermarket heads since?
Should be interesting to see if there is a difference betwwen your (stock) heads & some race heads.
Some people think stock heads are all that is needed to run fast? :2cents: :2cents:

 

[ed hess]

Re: Forced induction and flow...

What are all the sparks from the photo?
Have you tried to run a set of great flowing aftermarket heads since?
Should be interesting to see if there is a difference betwwen your (stock) heads & some race heads.
Some people think stock heads are all that is needed to run fast? :2cents: :2cents:

pic is from breaking axle and truck landing on caltrac, saving undercarriage.

aftermarket heads.... patience there buddy. its just about ready, fired it up nite before last.

stock heads.... yes you can run fast on oem heads. but there is a limit.

ed