I just wanted to start a thread on IDI head flow numbers. I dropped one of the "Jigblock" heads down at the machine shop to get flowbenched on a Superflow 600 bench, to see what they flow in stock form with stock valves. I told him to take it to .500" lift, the biggest cam around is NMB2's and that is ~.460" lift on the exhaust...

I will post the numbers up as soon as I get the head back.

When I start building my 6.9, I am going to port the heads, and after I am done, I will have them flowed again, so we can see what kind of improvement in airflow there is with porting.

Ill have the head back in a couple of days...

 

I've got a set of 6.9 heads u can play with if u want

 

Well we could take one of those down and see what it flows also...

 

who was it that said NEVER port these "they are to big already" i remember seeing a thread somewhere...he was for velocity, over flow, might of been on PSN.

 

i think i know who you are talking about.

 

Lol you guys ripping on me or something??

I have said that there isnt a real big benefit to porting these, the ports are pretty good as it is... That is true if you are just out for some simple mods, I didnt think it was necessary on my current engine...

But Airflow is airflow... I want to see what kind of gains can be had with some portwork... It might be 10cfm, it might not be necessary at all, it might be 50cfm... We wont know until somebody does it in this fashion... So Im going to do it ...

 

Port size vs port flow... The debate starts again... IMO You need a balance of size vs flow. Then the needs of a NA head vs Forced induction....It just never ends.....I will be interested in the Numbers on the stock heads vs ported and your reason's for porting and where you will be removing metal in the port. Intake and exhaust... This thread is going to be fun to read...

 

i know i'm not.

 

no not you lol i think it was xcite (spelling ?) he seemed to have some good info on the subject. what do i know tho i say try it

 

Absolutely... IMO the ports are too big as is.. The key is to take out a little material as possible to achieve the best flow... The biggest areas on these heads are the short turns, those could be improved a ton... Second would be a decent valve job, and third would be to work the bowls over, and last, clean up the flash in the ports, which is the worst I have ever seen in any head...

The biggest confusion people have with boosted engines, is that they think the air is being "blown" in... It is being forced in, but more pressure doesnt mean more flow, it just means more air is being pushed in at the same "flow"... Most people think that FI makes up for poor air flow... Thats not true.. It just increases density at the same airflow... So if your running 30 psi (3:1 pressure ratio), and you gain 10cfm with porting, you are gaining the equivalent of 30cfm on a N/A engine, while technically flowing only 10 cfm more... The problem with our heads, is that we have such little airflow through our engines anyway, that the huge ports (exhaust mainly) flow more air than we need... so porting does very little... But if we can improve the spots that are bad for airflow, we can gain that much more over the stock flow numbers... That means less boost for equivalent power, and a more efficient engine... At least we'll have hard numbers to base our opinions on... Thats what Im after...

 

Its awesome to see someone taking such an interest in R&D in these old engines. you have and nmb2 have done so much for the idi world in the past year its nutz! i envy you guys so much. your trucks are awesome!!! and your work just as awesome! great job keep it up!

 

Bingo....I agree The most we can hope for is to reduce the (BAD) spots in the port. The turns need work and the casting flash is Nasty. The valve seats need blended into the port bowl and the valve guide boss is huge. All this will help, Just how much we don't know ...YET

 

Thanks man, Thats probably the biggest reason I have taken such a path... For what I had into the original iteration of my engine, I could have put a cummins in my truck, and some would argue that I should have... However, I wanted to do something different... I decided on an IDI because it was an underdog... Fortunately through other venues/forums, I met NMB2, and with him having that much more time with an IDI, and being such a controversial figure when it all began, It created a motivation to do something with these fossils... There is something about somebody telling you it cant be done, that makes you want to make it happen... I dont care to re-live the drama of the early days, thats old news and worn out garbage, everybody got burnt out on it, and its not necessary, but I dont regret it one second, because it was such a driving force behind what has become of these things... So if anything, it can be looked at as a "blessing"... Its kind of funny because at first I looked at it more like a competition, but as time has gone by, and we have put more and more work into developing this stuff, it seems so rediculous to look at it that way, because we are revolutionizing a dead platform... To me, when every IDI guy who gives a damn is making 300+whp, a number that wasnt supposed to be possible last year, Ill be satisfied with what has been done... I dont like mis-info, and I dont like somebody telling me I "cant" do something... because to me, its just more fuel for me to do it...

 

Exactly.

 

One thing I have seen with higher flow numbers and decreased velocity with aftermarket heads in a diesel application, is that torque is sacrificed for top end power and to some degree it is slightly more smokey as well down low. I believe that can be attributed to the change in air swirl going into the cylinder. But as was stated before, it is essentially a compromise of velocity versus flow. I look forward to see your testing Justin! Keep up the good work man.