AnthonyNYC

I hate porting so when I ported my motor over a year ago, I used templates. I only cut the face of the irons and not the runners. I compared 2 templates, 1 was a racing beat one and the other was a pineapple one, both streetport templates. If you look at the pics you will see the racing beat goes up and in more whereas the pineapple goes lower and out. Well I decided to combine the two. The motor has been making 600HP and lasted all last season with a lot of abuse and still going for this season. Here's my question.



Do you think that I did anything wrong when I did this? I build my own motors and I tune my own car but I have no clue when it comes to porting so I am not sure if I did something I was not supposed to. The reason I am asking is is because the power I am making at 32psi is what others are making 5psi less. Granted they have better, larger turbos but I wanted to make sure my porting idea of using 2 templates is not causing any other issues that I am not aware of.



It sounds confusing so please look at the pics to see what I am talking about.



Thanks,



Anthony

Sukai94

WOW



May be the turbo. Stole this from the evil forum. It may be evil but they have some good reading there.



http://www.rx7club.com/showthread.php?t=645551

sen2two

what do you mean by "combined the two"? have a pic?



how did you port the exhaust, if you ported them at all?

Lynn E. Hanover

Interesting reading is right. So 10 PSI may not be 10 PSI depending on turbo size??



As is the case most often there is much missing from the question.



You say that you have two engines performing the same, but using different boost pressures. Boost measured with the same sensor, placed in the same place on identical intake manifolds reading the same inlet temperature, at the same engine RPM?



Difficult to do for a pro, with the correct equipment. So if you are comparing dyno sheets, check to see that the test RPMs are identical, and all other perameters are identical. So part of the answer may be right there.



This is all opinion, and may be worth what you are paying for it...............



For any test pressure your turbo can maintain, the bigger the passage you push the air through, the more CFM you will get into the engine. However.........that is only true until the pressure inside the closing chamber gets to be the same as the test pressure (lets say 10 PSI) so if you get up to 10 PSI in the closing chamber, only the energy in the velocity of the air will get any additional air into the chamber. So, the chamber pressure, at some RPMs may be higher than the actual recorded boost pressure. As in the NA engine there will be two RPMs where this works, based on the tuned length of the intake runners. Anywhere else it take boosted pressure to force additional air into the closing chamber.



Bernoulli (like Murphy) never sleeps. http://home.earthlink.net/~mmc1919/venturi.html



You have noticed that the intake port, even in a stock engine is closing after BDC on the intake stroke, and therefore, some of the ingested volume is being pushed back out into the manifold, at idle and low RPM. So now we come with the die grinder and change the intake closing point from 55 degrees after BDC to what? 70 degrees, ABDC, and now how much is air is pushed back into the manifold before the port closes. A bunch more. And there are two strategies going on with your two patterns. The Racing Beat is using mostly later closing to get more power up high, where a bit more torque give you a bunch more HP. The other pattern is using much more overlap (early opening) and lower port for a better connection to the exhaust to get a head start on intake flow and reduce back flow out of the chamber.

Probably better in the mid range.



The bowl volume is generlly thought to be too big in the stock port, and slows velocity too much for ideal power. Everything removed by the die grinder increses bowl volume, and slows the air entering the chamber even more. You want the highest possible velocity at the port face, and it is not there.



The much increased port timing should work well at higher revs. Make the high rev mods and jack up the oil pressure. Add intercooler capacity, I smell 700HP............





Lynn E. Hanover



In this picture, the closing point is 80 degrees ABDC.

AnthonyNYC

I opened the top of the port the same as the racing beat port, and I opened the bottom of the port, the same as the pineapple port.



The racing beat opens up the top further but leaves the bottom pretty much stock. The pineapple one opens the bottom area more but opent the top area just a little. As for the exhaust, I used the standard racing beat streetport.



Thanks for the responses.



Anthony

Judge Ito

my template looks and works better.. judge ito for president...

AnthonyNYC

I agree, yours has been proven time and time again.



After all this porting talk looks like you don't need porting to make big HP anymore! An rx7 member made 769 HP with stock ports and a stock eshaft. He was running a water to air intercooler, 76mm turbo and on gas (Q16).



http://www.rx7club.com/showthread.php?t=747542



Anthony

Old Grey

The template on the left is the way to go. Notice the sharp angle between the opening side and closing top (the top left corner of the port). The other pic on the right has a large radius at this position, I term these ports "side seal chipping ports", if you run this port your side seal trailing edges will chip and you will see a dint in the port at the radius. What is happening is the side seal is not being ramped and supported on to the flat plate before the tip reaches the flat plate. Side seals will bulge into the port when they pass over it and has to be gently and progressively eased back. Just put a mirror into the port while rotating and you will see the end hit the radius before the seal is supported

Silver7

Anthony - What do your primary ports look like?



Ito - I've been trying to contact you during the past couple of days to get some templates and possibly get you to fix up my existing ports.



If anyone has any ito ports that they would like to sell, rent, lend... please PM me. I only have about 2 weeks to get my motor back together and I still have some port work that needs to be done.

Judge Ito

973-653-4084