2 heads better than 1 - power porting E7TE iron.

[David Vizard]

Below are the curves for stock E7TE heads and stock rockers (black curves). next are the curves for RBJ racing's modified heads with Scorpion
rockers (blue curves) and lastly the DV/CS E7TE heads originallt shown a few posts back.

Lets be very clear here on the intent of the comparison of the RBJ heads and mine and Charlies. It is not a question of who can do the best but how two conceptually different dirivations compare. Thr RBJ casting are limited to mods that find the easy air whether it be by hand porting or machining with a form tool. The DV/CS heads were done with no consideration to time spent. Also the RBJ heads were done solely with reference to the airflow gained. Other than eyeballing it the RBJ heads made no reference to port velocities CD's, Port Energy or Port Energy Density.

Given the same circumstances, ie using the IOP porting program, I am 100% sure that John at RBJ could have produced like results to those that Charlie and I saw.

Before going on and looking at the flow bench figures lets quickly go through the results and see to what degree success was achieved.



Making a comparison of the RBJ and stock heads is are off the table as the RBJ heads had the benefit of roller rockers. That being the case we will need to compare directly with the DV/CS results and look at how much less the RBJ heads were than the DV/CS heads. From this we can then make a reasonably estimate of the power gained over stock when the effect of the roller rockers is taken into account.
Going this rout it looks like the RBJ heads were worth a solid 50 + hp Which demonstrates that if you know what you are doing applying even basic porting moves can yield some great results.

Now let's take a look at what the flow bench tells us and see if that corresponds to the changes in output.

[jcisworthy]

Thanks for the hard work you and Charlie have done in this endeavor David,

With a very small runner starting point on these heads it takes a ton of grinding even to do what I did to these heads. I cant imagine the time you and Charlie have into your heads.

Start to finish, rusty, dirty heads to ported heads loaded with valves, screw in studs, guide plated, resurfaced on all three surfaces, flow testing painted in bags ready to ship takes a solid 5-7 days labor plus parts without trying.

Like you said numerous times, with all the new aluminum offerings there, maybe the only time to do something like this is for mandated classes or a self "home porter" trying to save money.

It is rewarding to take a cast iron turd and polish it to the point where it makes substantially more power than stock.

[Carnut1]

Fully done up E7's 347ci bumpy roller cam and a hidden N2o system. Looks stock! Sleeper stuff, I love it. Haha.

[David Vizard]

let's look at the RBJ racing E7TE head and see exactly what John and his flow bench achieved. For that check out the graph below. Only if it is a quick and healthy increase in flow does John apply it to these 'production modified' castings. If it takes too much time to get the extra air concerned it is left on the table so to speak,

AS you can see the increase in airflow is pretty substantial indicating that John is well practiced in the art of using a flow bench to improve cylinder head performance. Just as a side issue here he can apply this 'production technique' to after market aluminum heads with effective results.

COUPLE OF POINTS TO NOTE HERE:-

#1 note the flow increases right from the get go not just at the higher lift points. This is the result of bigger valves and an increase in flow from better seat geometry.

#2 How much of the increase came from making things bigger and how much from making them flow more efficiently? The answer to that in the next post.
DV.

[David Vizard]

The co-efficient of discharge is based on the valve diameter. The more air it flows relative to the size of the curtain area it exposed around the valve the greater the efficiency.

A good multi-angle seat job utilizing a 45 degree seat typically produced a CD in the 70-72% range although some heads such as many of those from AFR consistently show CD's in the 73 -74 % range. These are industry leading figures.

A quick look at the graph curves and you will see the RBJ seats on both the intake and exhaust reach or surpass the 75% efficiently mark. So that good low lift flow is due, in large part, the Johns top grade seat geometry.

When lift gets too about 0.300 & 0.380 on the exhaust and intake respectively the flow becomes primarily dependent on the port size and shape it's self.

Now we can address the question of whether or not that whatever flow is achieved is done with the best balance between port area and port flow efficiency in a similar manner to that of the valves. Please heed that the port flow efficiency is a different deal to the valves flow efficiency. Although we can use the same technique to address it the best way is to see if the port's mean velocity reaches those figures which are known to work best in practice.

We'll do that in the next post.

[jcisworthy]

Thank you for posting that David, it's nice to see the efficiency results on the graph

I spent many months and a lot of money developing cutter profiles which work well across the board. Good to see it quantified

[Casper393W]

viewtopic.php?f=1&t=49585&start=60&hilit=Gt40x+heafs
Thread on development of gt 40 aluminum heads DV and Andy. Thanks, Charlie

I can't wait to see how they stack up against the E7's... While they did flow decent... The efficiency is nowhere near those heads.. from what I remember...

[Carnut1]

viewtopic.php?f=1&t=49585&start=60&hilit=Gt40x+heafs
Thread on development of gt 40 aluminum heads DV and Andy. Thanks, Charlie

I can't wait to see how they stack up against the E7's... While they did flow decent... The efficiency is nowhere near those heads.. from what I remember...

They did better at low rpm than I expected but got beat upstairs. Which is strange for a bigger port and higher flow numbers. That may have to do with the difference in compression. Thanks, Charlie

[randy331]

They did better at low rpm than I expected but got beat upstairs. Which is strange for a bigger port and higher flow numbers. That may have to do with the difference in compression. Thanks, Charlie

I'd say they just didn't have the right LSA for the FlowZ.

Randy

[David Vizard]

So let us now look at the mean port velocity of the RBJ ported E7TE heads versus stock.

We have already checked out the valve related flow efficiencies and seen the the RBJ valve/seat is far more efficient. We also saw that the flow went up considerably so if the mean port velocity is also up then it means that the port is not flowing more because it is bigger but more because it is a little bigger and is of a lot more efficient shape.

From the graph below we can see that the intake ports mean velocity was up by as much as 20% at the higher lifts and it also managed to hit the 300 ft/sec mark (thick blue curve) at a little over 0.500 lift. by the same token the exhausts mean velocity was down by almost the same amount. Whereas the slower exhaust port would be slightly detrimental it in no way offsets the advantage given by the 20% velocity improvement seen on the intake.

Although John uses a flow bench to develop ports his tests, on this occasion , where strictly to investigate and go with CFM increases only to get some idea if dealing with all the subsequent issues such as valve flow efficiencies, Mean velocity, port energy and subsequently specific port energy were of any benefit. I think we are beginning to see the advantages of porting for factors other than just outright CFM but I will leave you to assess the data when I am done here and come to your own conclusions.

Up next the controversial subject of port energy.

[David Vizard]

Randy,
your comment from the low lift flow on a drag motor thread:-



The question was, is your testing flawed because no cam change was made for the different heads ?

You've stated before that if there is a flow change the ideal LSA - ICL etc will be different, and you have questioned the results of others who have changed heads without a cam change.....

So based on your own belief and previous statements about flow vs cams, is are your tests flawed ?

Randy

No the tests are not 'flawed' although at this point in time and with the info you have that would be a fair conclusion.

Rather than the use of 'flawed' it would be more accurate to say that the tests had to have some compromises due to time and cost factors.

And since you brought the subject up to the fore I will go through the events and constraints that played a big part in our choice of what to do.

However you will need to be patient here because of a shortage of time, PRI looming and heads that need to be done.
DV

[David Vizard]

Many of you, including my cohort Charlie, have voiced an opinion the the 260 Flat tappet cam used was too short and lacked lobe lift for these tests.
I was in hospital with later stage congestive heart failure when Terry Walters Ford specialist engine builder called and asked what cam should be installed in the test engine. I told him it is the one in the Jones Cams box marked head test engine. So here I am 2 days from doing a seminar and and 6 days from an extended dyno session. Wednesday Jack calls me again and tells me that the cam is only a 260 degree grind on a 110 LCA. The box had 272 on it so I must have put the cam in the wrong box. Too late to do anything about it now.

Well Charlie and I made it to the test venue in Roanoke on the Wednesday as the break in was completed. The cam issue was still very much foremost in mind as the ported heads universally showed their best flow way above the 0.474 lift our 260 FT cam was delivering. Conclusion:- As Charlie would not let me forget this cam, in terms of lift to access available flow, strongly favored the stock heads. But, before going on lets not overlook that, in spite of this lift disadvantage the heads that we did, at 50 and 70 hp increase ,still show extremely well. Having started with the 260 cam I decided that we would at least run the other street heads and maybe my 289 race heads. None the less the short cam issue still bugged me so, this afternoon, I gave old Mikey over at Jones cams a call to see if he was willing to help out here (remember the 260, which was working very well for a true street grind, was a Jones cam).

Now what I like about Mike is that he has so much confidence in his products he is always ready to show them off.

Mike's thought's on the use of a 260 cam reflected those of many of you who have made the same statement. I told him that what ever we used had to still be truly streetable and he firmly agreed on that. In so many words he also commented that by hook or crook the valve lift ultimately had to allow the high lift flow to be accessed by the cylinder. Mike made the suggestion that we go to a slightly longer 268 hydraulic roller cam that offers much more opening area with only a little more duration. The new cam then will be a roller that replaces the 260/204 -474 lift FT deal with a 268/220- 512 lift roller. And for those who want to see yet a bigger cam we have a grind up in the 290 range for the final tests with the race heads. (Are you happy now Charlie??)

DV

[Carnut1]

Very happy, Now if we could just get some thin head gaskets donated to fix that miserable quench I would be thrilled! I know, I am a pain. I will add that the larger cam and fixed quench with some timing runs will cut deep into that stock block's max strength limits. Thanks, Charlie

[Carnut1]

I would like to mention that the Quickfuel 750 carb seemed to make easy work of a little 306 with a mild cam. I think it had stepped down leg boosters. I bet it will really pay off with the bigger cam and higher rpm demand. Thanks, Charlie

[travis]

I’m curious why the 268/220 .512” lobe, instead of the 268/218 (or 222) .544” lobe Mike has at his disposal?