2 heads better than 1 - power porting E7TE iron.

[David Vizard]

Again I want to re-iterate that the use of a cam as short of 260 degrees, though not intentional, will tend to highlight cylinder head attributes (see my last post) other than just airflow. Here we have a cut and clean result. Even with such a short cam the heads that Charlie and I did are a solid 70 hp up on the stock ones even with the CR almost unchanged. To put this in prospective try and find an aftermarket set of heads at any price that will bump the power to this extent!! You won’t but we will look at some of the best just for the sake of comparisons.
DV

[David Vizard]

So why did the mods on these heads work out so good?

The fact of the matter is that the heads were good in all quarters.

First check out the flow increase in the graph below. From this you can see that the modified head (thick Lines) was better by far from the stock heads.

There was a big increase in low, mid range and high lift. Results, though not conclusive, indicate that massive low lift flow increases are not the disaster some head porters/engine builders seem to think they are. The high flow radius seats - contrary to some reports- seem to be working just fine.

Note also with an intake valve lift of some 0.474 the cylinders can access a substantial increase in airflow without having to resort to a high valve lift.

But is this increase in airflow the sole reason for an increase in output?

To see what else may be lending a helping hand here lets move on to the SAE discharge co-efficient.

DV

[Carnut1]

Not perfect but not too bad. Video of E7TE run Charlie DV heads scorpion rockers.
https://youtu.be/TSg7SMHgPY0

[David Vizard]

Looking at the flow efficiency shows that our port was exceptionally good at low valve lift. The radius (actually I should say semi radius) valve seat is showing just over 86% efficiency at 0.150 lift compared to 61% for the stock configuration.

At high lift (0.500) Our modified intake port bottoms out at 54% efficiency while the stocker bottomed out at 43%

The curves on this graph also indicate whether or not there was room for improvement. If the amount of bias in the port bowl is optimized the CD curve, after the inflection point shown by the vertical blue lines, will climb quite steeply. For a head of a like configuration to our E7'S that climb after the inflection point can be as steep as 30-35 degrees. Although we see there is a tendency to climb after the inflection point the amount is small.

So why didn't Charlie and I take advantage of more bias as the IOP program suggests? Here's the simple answer - casting thickness and valve lift.

Between Charlie and I we have had more than enough experience with ventilated castings and stopping just short is better than a step too far.

Also if maximum lift is only going to be about 0.575 with whatever cam is used then porting and consequently removing metal will only cause the port velocity to drop in the lift range used. That is not good.

Next we will look at the velocity curves and see where our porting job falls when compared to stock.

[Carnut1]

DV has it right. Tough to port bias these enough due to casting thickness in the bowl. Even at this level you need to have a good ultrasonic thickness tester to prevent sprinkler action. Thanks, Charlie

[RevTheory]

Did you guys happen to mold any of these ports for a visual reference?

[David Vizard]

Here is a port velocity diagram for the stock and modified heads.

The goal, when using the IOP program, is to have the mean port velocity of both intake and ex. at or above 300 ft/sec at full valve lift.
The stock head tops out at 236 ft-sec while the modified one just surpasses our 300 ft-sec target at about 0.450 lift on the intake and 340 on the exhaust at full valve lift (0.474).

So we have picked up both flow and velocity. As far as the maximum mean velocity see in the ports we should try to get the intake between 300 and 330. As for the exhaust 300 - 350 is what we are looking for.

If both the velocity and flow have gone up than what does the port energy look like - that's the next graph.
DV

[David Vizard]

Before you read any further go and check out the port energy graph and note where in the lift curve the port energy has gone up.

Now you have looked at the graph you can appreciate how much the port energy has gone up by. The fact is it has almost doubled. A before and after port energy increase like this indicates the heads concerned will show a considerable increase in power with a lot of that coming from an increase in torque plus an ability to hang on better at higher rpm. That higher port energy ram filled the cylinders better than the stock heads. It also cut reversion.

With all the stock castings limitations, skilled use of a die grinder, seat cutting tools and the IOP program resulted in 70 HP increase in spite of the short test cam used. But these heads used every trick in the book plus some that are not in any book. And the time involved was over the top. I can see only three viable reasons for going the 'stock ultimately ported factory iron head' rout to greater output. #1 Vintage racer that has to use factory period original castings. #2 A stealth motor for street and match racing. #3 you have no money for a set of aftermarket heads.

Starting with a good aftermarket aluminum casting and doing this much work will yield much better results as we shall see down the road.

The next set of heads we are going to look at on our dyno mule is a set done by John Rossello and kindly donated to the test program with the intent of helping defray the costs involved by yours truly. I like to call this type of head modification 'production porting' as it is a process that seeks only to find the 'easy done' mods thus cutting costs/efforts to a minimum while still netting good dyno results. Look for that in my next post.

[qikgts]

To put this in prospective try and find an aftermarket set of heads at any price that will bump the power to this extent!! You won’t but we will look at some of the best just for the sake of comparisons.
DV

I honestly believe you guys have done some great work! However, please check out this segment of a SBF cylinder head shootout that was published several years ago in MM&FF. The link is below. Wayback Machine is the only way I could find it.

https://web.archive.org/web/20101212175 ... 2/A-P1.htm

Cruise to the last page of that article to look at a summary of the numbers. I'm pretty sure there are several sets which performed really well. As good as yours Mr. Vizard and Charlie? Perhaps but nobody will know for sure considering dyno time is so expensive, no two dynos are the same, etc...

[Stan Weiss]

I think that on the first page is some very important information.

Comp Cams supplied our XE264HR cam. The cam offers .512 lift, a duel-pattern duration split of 212/218 at 0.050 ground on a 114 lobe separation angle.

Not really an apples to apples comparison.

Stan

[Carnut1]

I am hoping DV does is next bunch of tests use a lumpy hydraulic roller 280@ .002 .56 lift or so and fix the quench. -.018 in the hole with .038" gaskets as it is now. I think with my E7's or either set of 289's it will hit 400 hp.

[BILL-C]

Those 289 heads are capable of making 450 +on the right engine.

[qikgts]

Not really an apples to apples comparison.

I think DV made a poor choice of words there.

The Holley's picked up 71 hp compared to the E7's in that test. Baseline to results.

I'd say it's like comparing a Granny Smith to a Crispin. Feel free to disagree.

Know I'm not hatin' on anyone.

However, NOBODY should ever say "You won't" unless it's true that NOBODY can't. Simply, I prefer to not deal in absolutes.

[Carnut1]

Those 289 heads are capable of making 450 +on the right engine.

Thanks Bill! I know you know what the 289's can do.

[David Vizard]

Not really an apples to apples comparison.

I think DV made a poor choice of words there.

The Holley's picked up 71 hp compared to the E7's in that test. Baseline to results.

I'd say it's like comparing a Granny Smith to a Crispin. Feel free to disagree.

Know I'm not hatin' on anyone.

However, NOBODY should ever say "You won't" unless it's true that NOBODY can't. Simply, I prefer to not deal in absolutes.

qikgts

I am totally confused here - which choice of words were you referring too?

The Holley heads were not stock castings so how do they figure in a test of ported stock castings Vs stock castings??

And the rest of your post is also not making sense to me. What am I missing here??

DV