427 coming along

[tpepmeie]

Originally Posted by Polo-1

You maybe farther along then me, but I know I have something you don't

Kevin, obviously there has been a mistake... that should have shipped to Indiana. Please forward it at your earliest convenience.

[tpepmeie]

Originally Posted by scholtmj

Could you explain a little more on why you went with "smaller" runners? I thought siamesed IHs were the thing to do on big cube motors. Thanks!

Well, I left the runner size up to the professional doing the work. As long as we got adequate/big airflow through the port and not too small as to cause choke, then the smaller runner will increase charge velocity. WIth this size, the nominal calculated velocity through the runner would be around 100 m/s (329 ft/sec). Not excessive by any means. The cams are being designed with these port areas in mind to take advantage of that velocity at IVC.

The inlet tract is not uniform in area throughout. There are different shaped areas to control the airspeed and help it turn the convoluted bends our manifolds make.

Probably everyone has their own theory on airspeed/port area for these motors. I trust the guy who did the work in this case. The dyno and track will be the judge. Can always go bigger later.

Todd

[Paul Workman]

Originally Posted by scholtmj

Could you explain a little more on why you went with "smaller" runners? I thought siamesed IHs were the thing to do on big cube motors. Thanks!

I believe he's referring to the "neck" at the runner/valve bowl area (adjacent to the valve guide (here on one of my work in progress heads)???.



One wants to avoid cutting the short radius which means more cutting on the long radius side of the curve...AND there is just so much metal there between the bore and the water jacket. As Marc explained to me; "85% of your liability lies in that last 15% of the metal removed (there)." Getting all the way to 36mm at the "neck" can be done, as many have gone there before. However, all technical advantages aside, getting there is not w/o some risk.

As for the "siamesing" the runners, that is often what is done to the plenum and to (at least) the inlet side of the IHs; sometimes more - depending on the guru doing the porting. The runners splay as they approach the valves, and there is water jacket between the runners in the heads, so siamese necessarily has to end there, if not (waaaaay) before.

Note to self: Next time pull the guides instead of trying to work around them. It would save hours of time, and the finished product looks mo bettah to the eye, if nothing else...

P.

[Paul Workman]

Originally Posted by tomtom72

...( off-set grinding ) of the crank ( what is that btw? )
grasshopper

Off-set grinding to lengthen the stroke...voila! (with some obvious liabilities beyond a certain point...)



This here mekanikal chit is almost as much fun as e-letroniks!!

P.

[tpepmeie]

Originally Posted by Paul Workman

I believe he's referring to the "neck" at the runner/valve bowl area (adjacent to the valve guide (here on one of my work in progress heads).

No, Paul, my post a couple above was talking about the injector housing size. At the entry to the housing where it meets the plenum, my runners are well under 36mm. The port in the cylinder head is another topic altogether.

Originally Posted by Paul Workman

At issue is the fact that one wants to avoid cutting the short radius which means more cutting on the long radius side of the curve...AND there is just so much metal there between the bore and the water jacket.

Hmmm. I can assure you that hours were spent on the short side radius on my heads. In fact, the "long side" of the turn does not need much material removed at all. The majority of the flow loss occurs on the short side. Shape is everything there.

Originally Posted by Paul Workman

As Marc explained to me; "85% of your liability lies in that last 15% of the metal removed (there)." Getting all the way to 36mm at the "neck" can be done, as many have gone there before. However, all technical advantages aside, getting there is not w/o some risk. I don't know what exactly the impetus for their choosing the neck diameter they did, but there is a practical reason for sub 36mm...is my point.
P.

I won't go into all the details of my ports, but the minimum cross sectional area on a good 4-valve head is not at the seat, but further up the port before the turn. In fact, it is not unusual to have a minimum cross-sectional area equivalvent to 80-85% of the valve diameter. Work that out for a 39 or 40mm intake valve, and it is nowhere near 36mm. Our castings are already larger than necessary in that key area, as well as the bowl below the valve. At least according to my guy.

That's not to say the port is small the whole length. The fact is it has to be larger in some areas simply to get the right shape to help the air turn without losing flow.

We'll have to see how it runs. The fact that he got great flow through the heads and housings without going huge or siamesing the housings is remarkable. Not saying it is the only way to do it, but it is a different concept.

Flyin Ryan, back me up here.

Todd

[jonszr1]

gosh i would love to hear what ryan has to say on this subject . he has so much knowledge in this area . ryan have you ever thought of doing porting to a set of housings heads and plenums to see what you could get out of them . if you would like to play with a full set up i have an extra seup that i would be happy to donate to the cause

[Polo-1]

You fancy high tech guys, and your cross sectional area, short side radius, short side radius................

BIG HOLE......... BIG POWER.............

[tpepmeie]

To each his own. Those look nice too.

PS. still havent got the throttle body yet, is it on the way?

[Polo-1]

in the mail next week

[flyin ryan]

Originally Posted by tpepmeie

No, Paul, my post a couple above was talking about the injector housing size. At the entry to the housing where it meets the plenum, my runners are well under 36mm. The port in the cylinder head is another topic altogether.



Hmmm. I can assure you that hours were spent on the short side radius on my heads. In fact, the "long side" of the turn does not need much material removed at all. The majority of the flow loss occurs on the short side. Shape is everything there.



I won't go into all the details of my ports, but the minimum cross sectional area on a good 4-valve head is not at the seat, but further up the port before the turn. In fact, it is not unusual to have a minimum cross-sectional area equivalvent to 80-85% of the valve diameter. Work that out for a 39 or 40mm intake valve, and it is nowhere near 36mm. Our castings are already larger than necessary in that key area, as well as the bowl below the valve. At least according to my guy.

That's not to say the port is small the whole length. The fact is it has to be larger in some areas simply to get the right shape to help the air turn without losing flow.

We'll have to see how it runs. The fact that he got great flow through the heads and housings without going huge or siamesing the housings is remarkable. Not saying it is the only way to do it, but it is a different concept.

Flyin Ryan, back me up here.

Todd

Don't need to, Your doing great, Todd..'Really'! Your 'Guy', wink, wink, has taught you well on his methods...not that you didn't know anything before...not saying that . Understand...& I've said this on here before, I don't come on here to talk about engines, I come on here to 'Not' talk about them. For engine stuff, I hang out at Speed Talk & YellowBullet. I will say...how do I do this with-out pissing people off....? What I've found on here is a bit of an 'Old boys club' when it come to engine building & more specifically porting. Not enough of an open mind to what is being done today outside of the ZR-1/LT-5 bubble. Make it big, make it big, make it big...Seems like everyone is fixated on the 36mm thing. No thought given to taper & air speed, just focus on 36mm..., don't get it. It's all about air-speed & more importantly 'Mixture' speed. Tumble, turbulance, swirl, mixture motion, node waves, sound waves & velocity. A smart person once said the 5 most important things when it comes to port work is Velocity, velocity, velocity, velocity & velocity...so ya', it's important. Make the area bigger, the air speed slows down, not speed up! Making it 'Bigger' can flow a little more air, generally but not as a rule, but won't do anything to make air speed up. When I port, I want to keep the port as small as possible & move/flow the most air. Have to keep the airflow coefficients in check, can't just make them bigger & call it done! Work out the area people...these things are damn big out of the box! Not saying they are perfect. I'm into shapes, not size. The only time size becomes an issue is when your approaching an area where it becomes a choke, guys on here are making area's way to big that are already a good size. I'm not doing a very good job of not pissing people off, I can tell that already . Todd's program is current, that is the way heads are currently done by top teams, Nascar, NHRA, F-1 etc., trust me. Your stuff, Todd, sounds almost exactly the same as the way I did my heads last spring, Jeffvette knows the power it made but I think he's the only one. Siameseing...I don't even want to get into that, I'll for sure turn eveyone into haters against me, LOL. Didn't want to jump in here before but since I was called out, that's my 2 cents. You know what Todd, I'm not even excited to see how your deal/heads etc. turn-out,...I 'Know' it's going to be good, I have absolutly no doubt...as long as the cams are made proper, nothing crazy big etc. you'll be a happy person .