EQ – all-time best BBC iron heads?

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EQ – all-time best BBC iron heads?

Post by David Vizard »

About two years ago, before I had my emergency brain surgery, one of my engine builder friends, and I can't remember which one, asked me if I had tested the EQ iron big block Chevy heads. My answer was 'no'. I asked him if he had and how well they may have worked. I got a one-word answer – dynamite!

So I called my buddies at EQ and asked if I could get a set of heads for test purposes. Two weeks later two heavy boxes arrived at my shop. And they were heavy - 80+ lbs apiece. When I got the boxes open I found some really nice looking castings - checked out the ports - they look good. I have to say the rumors were that Chad Spears had something to do with the design of the ports and chambers on these heads. I think the original design though was by Peter Hill who hails from New Zealand. Any way up on the flow bench they went.

The numbers were that were produced from the out-of-the-box castings looked very promising as the following chart indicates.

Lift InG InB Ex
50 36.5 36 27.2
100 78.8 79 67.3
150 117 117 95.4
200 158 157 120
250 199 201 141
300 229 227 159
350 260 259 177
400 292 293 191
500 358 356 216
600 386 378 233
700 370 368 247
800 369 365 259
900 - - -
1000 - - -

All good numbers as I am sure you will agree especially from intake port only 320 CC. Now all this happened just before Marvin and I were about to give a 10 day tech/hands-on course on head porting. Four of the students had particular interest in big block Chevy's. I like to start my guys off on iron heads because I've got plenty they can scrap. After checking that the four concerned were competent at cutting metal I put each one porting two cylinders of the EQ heads so that encompassed both good and bad ports. One of my students, who appears to want to remain anonymous although is a regular poster on ST, cut some exceptionally good ports. The good port flowed up to almost 435cfm and that was with just 2 1/4 inch intake valve.

Now the next event of significance was I needed to spec a cam for a couple of guys who had a budget orientated racecar that was in really really pristine condition in terms of bodywork etc. They wanted me to spec a cam for a 500 inch big block Chevy that had only 2.06 intake valves in the heads. Unfortunately an optimum cam for a 500 incher on 11 to 1 compression and a 2.06 intake valve results in a cam spec that no blanks exist for. So I called these guys and told them that and during the conversation they said well we might be in the market for a better set the heads if there was something that would work and they could afford.

Well guess what! DV had some nearly finished iron EQ heads. Rather than indulge myself in another extended porting program going back and forth to the flow bench I decided just to copy my students port and go with that. Another reason for this is that with my physical condition I am limited to picking up 25 pounds so getting an 80 pound iron big block head on the flow bench was simply not on the cards. For the finished head flow tests I got my next-door neighbor to come over. He is a retired pro baseball player and just happens to be in one of the halls of fame. the results for such are shown below.

Now here's my question. I don't have experience with that many of the aftermarket iron heads. So, from an intake port of just 332 CC how do these ports stack up against other brands that any of you may have done?

Lift InG InB EX
50 39.5 39 33
100 83 84 69
150 125 125 97.5
200 165 163 123
250 208 206 150
300 250 247 169
350 286 284 190
400 319 316 215
500 370 368 247
600 410 406 273
700 424 418 303
800 432 424 306
900 437 428 309
1000 439 430 311

If the interest is there I will post some of my graphs showing the port velocity, CD and the port energy density.

DV
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Re: EQ – all-time best BBC iron heads?

Post by vortecpro »

I've had excellent results with EQ BBC heads myself
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Re: EQ – all-time best BBC iron heads?

Post by Walter R. Malik »

Talking with the E/Q guys at the PRI show, I was told those heads have gone through a few changes since the original dies were made from the Peter Hill / Pro Action originals way back 20 or so years ago.
I am sure all the updates of those dies, from one owner to the next, got them to flow a little better each time.
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Re: EQ – all-time best BBC iron heads?

Post by mag2555 »

Hi David!

Yes it would be great to see the velocity profile on these heads, and it great to see you not only back on here but I hope recovering well and feeling better every day!
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Re: EQ – all-time best BBC iron heads?

Post by David Vizard »

Thanks Mag.
I will get around to posting the 'colorful fancy hi-tech graphs' as so as I can get ouit from under a laod of engine work.
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Re: EQ – all-time best BBC iron heads?

Post by rapidride2 »

Hope to hear more about these heads as i am a fan of these types of 'sleeper' engine parts.

Anyone know if the 320cc port is better than the 360cc port they offer?
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Re: EQ – all-time best BBC iron heads?

Post by RevTheory »

May I offer a quick pic while we wait for David?
IMG_0652.JPG
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Re: EQ – all-time best BBC iron heads?

Post by David Vizard »

Guys,
The fact of the matter is that I did not know that EQ offerd a 360 cc version. Has any ST poster experience with this version.

Rev, thanks for the pic I had forgotten it was shot. Shows the great workmanship of a student who appears to be just a gifted head development engineer in the making.

DV
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Re: EQ – all-time best BBC iron heads?

Post by rapidride2 »

It is only here say but the 360cc port is supposedly lazier than the 320cc port. A lot of pullers use this head. Hopefully someone with actual experience with these heads will chime in.
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Re: EQ – all-time best BBC iron heads?

Post by David Vizard »

OK here we go with the graphs for the BBC EQ heads. (started at 320 cc). For those who are not up to speed here and don't criticise for the sake of it here are some very pertinent details presented in those fancy colored graphs that I wrote an X-cell program to produce rigt off the flow bench or dyno. They are what is considerd publication quality and for those who think fancy colored graphs are just over the top I make no apologies for doing the job right.

First the flow curves.
The guys who are building the motor for the heads need to retain some semblance of reliability so I adviced them not to go too much over 800 thou lift. Since they wanted me to do a full cam spec I ran the numbers thru' my cam selection program and then handed it all over to Terry Walters Engines in Roanoke to supply the parts and cam as called for.

Note that my gifted student porter deliverd about 435 cfm at 800 lift point and about 10 less on the 'bad' port. These look to me to be some very good numbers considering it is all done with 332 cc intake ports.

I should mention that there will be some heads out there that outflow these but are very likley doing so because the ports are much bigger than those used here.

One of the big problems the 24 degree BBC heads have is that it is very hard to get both good flow and velocity. Those bigger ports make for a 'lazy' torque curve which could well be why some are saying the 360 cc version of these heads does not seem to produce the goods in a crisp fashion.

Well I will address the Discharge Coiffcient in the next post. Meanwhile your comments please.
DV
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Re: EQ – all-time best BBC iron heads?

Post by David Vizard »

Here we see the discharge coefficients of the intake [blue] and exhaust [red]. Note the two vertical lines on the graph. These represent the .25D lift value often just referred to as the quarter D lift. At this point for either valve the amount of maximum area that it can present to the cylinder has been achieved. Lifting the valve any further than this does nothing to increase the available area for the intake charge or exhaust to pass through.

The shape of the curve after it passes the quarter D lift point can be very telling. If the line goes flat it indicates that the port has insufficient bias towards the center of the cylinder. What this means is that the full extent of the fact that the valve is now out of the way of the seat is not being fully utilized. The flow neither enters the cylinder or leaves it in a line straight with the axis of the port. The fact that it shrouded on one side means that there is a preferential path towards the center of the cylinder and away from the cylinder wall. Unless the flow is given some encouragement by shaping the port appropriately to bias the flow towards the center of the cylinder this high lift flow potential will be lost. Inspect the curves past the quarter D lift point and you will see that the exhaust has a big upturn in efficiency and then levels out. The point at levels out here is probably because the port can be thought of as being saturated.

It may be possible to coax more flow out of the exhaust port but that may it be at the expense of velocity. We will find out just how well we're doing - or not- as the case may be, when it comes to analyzing the ‘specific port energy’ of the port. If we make the port too big the specific port energy will drop even if the flow goes up. What this means it is we sacrifice too much velocity for flow. That rarely works out to our advantage.

Now let's consider the intake. Although the valves on a big block Chevy are angled and canted the overall port performance is less than it might at first seem.

Note that the intake, after it reaches the quarter D lift point, only rises slightly and then levels out. Getting the intake port discharge coefficient to climb in the same manner as the exhaust is a very difficult deal. It becomes very necessary to strike the optimal balance between the mean port velocity and the flow. Again we have to refer to our specific port energy figures to determine if we have achieved something around optimum here. If these numbers look good we are home and dry in the knowledge that these heads will produce very positive results.

Next graph will be port velocity of both the intake and exhaust. With the IOP program which is generating these curves, we need to see something in the order of 300 ft./s plus to be sure of getting good torque figures especially in the lower RPM range.
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Re: EQ – all-time best BBC iron heads?

Post by RevTheory »

I sure wish you got more traffic back here.
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Re: EQ – all-time best BBC iron heads?

Post by skinny z »

RevTheory wrote:
> I sure wish you got more traffic back here.

In as much as I'd like to contribute, I'm more about absorbing the information. I've offered a few insights and requests for information on past DV threads however I'm often the last to post and the thread just kind of goes stale.

And I'm a fan of the "fancy colourful graphs" as well.
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Re: EQ – all-time best BBC iron heads?

Post by skinny z »

skinny z wrote:
> RevTheory wrote:
> > I sure wish you got more traffic back here.
>
> In as much as I'd like to contribute, I'm more about absorbing the information. I've
> offered a few insights and requests for information on past DV threads however I'm
> often the last to post and the thread just kind of goes stale.
I hope that doesn't happen here!
>
> And I'm a fan of the "fancy colourful graphs" as well.
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Re: EQ – all-time best BBC iron heads?

Post by David Vizard »

Many are probably unaware that, when seaching for good flow numbers, the 24 degree BBC tends to suffer from poor port velocities.

All too often the seach for flow is done without reference to the 'mean' port velocity. Shown below is the velocity charactoristics of the EQ BBC head that I am looking at here and posing the question 'is it the best iron BBC head out there?'

As a good guide the port velocity at full valve lift and as determined by my IOP porting program is 300 to 330 ft/sec for the intake and 310 to 350 for the exhaust. As you can see my 'port gifted' student's port ran really close to the 300 mark for the intake and over that for the exhaust.

That's good but how well does it stack up against other BBC heads, iron or otherwise. Answer - really good. Most of the better heads out there ported by accepted experts rarely run better the about 270 to 280 Ft/sec.
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