This is a new topic so I've taken this opportunity to make a new post with it.

 

John hasn't thrown any numbers or expectations out there yet.  Testing will determine this but with improved out of the box flow numbers over the stock heads then an increase in performance is also to be expected.  But raw air flow numbers are never the whole story as improved valve locations, combustion chamber design, and port configurations also play a large part in overall performance.  With the combustion chamber cc’s being downsized to compensate for the inefficiency of aluminum in regards to heat retention, then at least the gains from the other improvements will not be offset or taken away by the use of aluminum.  It will also make sense that for the anticipated increase in air flow for the new heads to be fully taken advantage of, the camshaft, intake manifold, ignition, and exhaust all must be upgraded to match.  Just putting the new aluminum heads on a dead stock engine may or may not see any significant gains in performance but testing will help to quantify this.

Lorena, Texas (South of Waco)

I did a run using ENGINE ANALYZER PRO, AFR 165 heads Y block short block dimensions, Headers, a lot of guessimatang on intake tract dimensions etc, a 214 degree @.050 in/ex 112 lobe centers, can get 325 to 370 hp @ 5000 rpm. The above were using a 735 Holley. A 1000 CFM dominator adds about 15 HP. And before anyone goes nuts I know a guy that successfully ran a dominator on a street 302 Mustang. Lot of work with on board mixture analyzers and so on but they will work.

I would expect to achieve in excess of 300 HP on a very mild street engine very possible. The use of good soft ware to build an engine, tailor header dimensions, camshafts is very viable. Intake tracts, and exhausts have a bunch of horse power in them.  

TO teds point about head design AFR heads may not flow as much as some others but they produce on the dyno. (Not talking nascar here).

Ted: the rule of thumb I recall is 2.2 HP potential (engine) HP for each SCFM of airflow into the cylinder assuming a proportional exaust. This is per cylinder of a V8 engine.

This is air into the engine, and as you have pointed out the total engine package needs to be optimized. The restrictions of the air filter, carb, intake manifold, etc must be dealt with. Increasing the airflow through one area makes the other restrictions more important. A 200 SCFM air filter will not allow a change from 150 SCFM port to a 300 SCFM port to realize any where near its full potential.  All of these restrictions are additive.

Pursuing the optimum carb, runner, port sizes, header (tube sizes and length) exaust system configureation, for power and driveability is a real challenge.

The 2.2 HP potential is reached only by the best engines at high RPM. My paper mild street engines see less than 500 CFM total (250 per port) flow  for a 370 HP engine. Nascar engines flow around 400 SCFM per port and produce well in excess of 800 hp.

Since Ted's dyno session with the new heads is only a few days away, I couldn't resist continuing this old thread.

Ted's dyno mule 312 is now well documented.  The peak power of the mule at 290 +- a couple HP was right in the area of what I've heard from other people who have dyno'ed stock head engines. I was a little surprised at the peak torque of a little over 340. Even with ported heads, most 9.5:1 street engines only make 350-360 ft lbs.

With that in mind, what we are really hoping to see is an increase in peak torque and the ability to hold a good number to higher rpm. This is what horse power really is.

Anyone care to speculate?

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

John,

I agree entirely that a broad spread of power is more important than just peak Horsepower.  An engine that makes plenty of power down low is a joy to drive.

Today when I look at either buying a vehicle or building an engine driveability is one of the first things I look at and stays paramount in any decisions made.

I recently had a set of heads (motorcycle) done where flow wasn't the major objective. The heads flowed reasonably well anyway but there was a design flaw which meant much of the incoming charge went straight out the exhaust. The intake valve was recessed in effect shrouding the valve and the port was modified to direct the intake charge at a steeper angle.  The result, less intake charge out the exhaust, the spent charge was cleared more effectively, greater turbulence with the intake charge mean better combustion. About 15% increase in performance but all the way through from idle to top end.    

Now from porting you would know how to improve the ports but you've also changed combustion chamber and spark plug location. These are the things that will make a difference across the whole power band. As long as you've got them right

I find it exciting that someone has taken on redesigning heads for the Y block. And we're getting updates and details as you progress. Happy days.  

Grizzly (Aussie Mainline)

I just got off the phone with Wally Kirsten, he finally got to run his car with a pair of the new ported heads. The motor is his 329cu in version. He made 5 runs, with a best of 12:24 at a thundering 113 MPH. Thats a big step from his prevoius best. My hats off for his effort.

Greg Dietrich Mt.Morris Il

Greg.  That’s pretty impressive performance out of Wally’s ’56.  I don’t recall exactly what Wally’s previous best was but this sounds like at least 0.4 seconds which is an easy 50-55 horsepower increase considering the weight of Wally’s car.

Lorena, Texas (South of Waco)

I was there and Wally was smiling.  He told me his previous best was 12.65...I think.  He needs to increasw his carb jetting, maybe he can get it down a little more.  The car sounded great.

Paul J. - '57 E Code

Hats off to Wally, he is probably now getting both tires off the ground!

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?

Hey  John and all the guys;    thought I would update you on our Bird(55 with 331 stroker--  Engle cam--Holly Nascar prepared by Ted Fleetwood --Sanderson Headers---MSD dist.  and John's heads.    On 2/28/09 I had a dyno pull  Max Power was 223.56 and torque was 227.74.  At that time had a Edelbrock carb and Converted Pet. dist. Also was running out of fuel after 4500RPM.  Added 3/8 fuel line.  Today we did another pull     Happy to say,, BELIEVE those heads work!!!    Max Power 271.71  and Torque 282.60!!!  these numbers are at the rear wheels.   Mulitied by 1.29  believe the flywheel would be 385.   Ted please corect me if that figure is not right.  Gain of almost 50 HP and 55 lbs of torque.  Pretty good.  Also noticed a great increase in Vac. with the new heads, idle between 13 and 15. Slight stumble just of idle, will change power valve to 8.5  from 6.5.  Going just a taste lean at 5500RPM. Will let you know.     All in all quite happy with the outcome and sure made some scrub guys come over and look, exhaust sounds soooo coool at 5500, somme chins hit the floor  HA HA.    Thank You all for all of you help thru the years, an honor to be a part of this forum!!!!   God Bless      Eddie

Eddie

Lake Forest, Ca. 92630