Inliners International Forums General Discussion Hi Performance Lump Ports & things to know about Your Head

First off...you can't get rid of the chat room..what in the hell will I do on tuesday nights?


Second...people post links to information all the time, seems to only play fair, all links to useful information should be deleted. Someone must be really bored with their life, to complain that someone put information up to improve others vehicles...

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I don't pay to advertise here or in the 12 port. well Not as of yet anyway. But as soon as the added dollors let me then I will. But for a Personal Business web site. This type of Links Is not aloud by the club. Because Other wise We'd ever TOM & JOE Posting here wasting Our Club Space.

As for The Chat room We'll just go back to the clubs Old one. But how ever I will still have the The chat room I set up in the first place. Depending on the Emails We'll see where WE?? ALL deside to Meet up. PLUS We haven't had a Very Good showing to the Chat the Past Few WEEKS.And I thought It would be in the Better INTEREST to have mine Removed so No Other Conflicts Could?? or WOULD ?? become of it.So if u want to stay with what I set up Just Book mark the Link.

#3220 }[oooooo]

HAS anyone used a 194 head on a 250 with domed pistons?Any trouble with this set up? The reason I ask is I have a ported and polished head I BOUGHT THAT HAS NEVER BEEN FINISH MACHINED

Yes and depending on the amount of dome. YOU will be pushing any where from 12.5-1 to as much as 15-1 compression. and the stock Bolts will not handle that much compression. Neither will the stock type head gasket.

The 194 I ran on my 250 with a domed piston cut as a 3staged pistion(which means the dome had two different heights to it) and this head was mill more then .010 Because it was Milled once before I had to cut .010 off it because I had the stock Bolts and a stock gasket at the time IT Burned a .010 groove into the head. and I was Pushing some where between 13.9-1 & 15-1 Just from what the CCs were on the head it was a guess of the 13.9-1 & 15-1 compression I never did CC the block
Anything above 12-1 You should run Studs at the very least. More then that it is wise to have the block O ringed.

There seems to be a tremendous amount of tech data being offered and or suggested on cylinder head mods i.e. lumps , separate intake ports etc.

Devoid of this discussion has been the single most important variable in port modifications. Street and strip, pick up trucks. performance cars, all need a 70% exhaust port ratio to intake flow. If that ratio is not respected, your hard work is all for not.

If you "increase the port velocity" with the lump mod in the intake, this has to shake hands with the exhaust port flow. A 10 cfm flow improvement with the port balance being maintained is a huge power improvement. A 40 cfm intake flow improvement with no proportionant exhaust flow improvement is good for absolutely nothing.

There are lots of those old Superflow 110 benches around....cheap. They can only pull 10 inches of water at high valve lift , but you will learn a ton, quickly. All your mods will make sense then and you will be amazed at what matters and what doesn't.

A stock iron head that has the port ratio installed will out run any welded, glued and screwed head with sexy looking ports.

What do yu call cheap I know of two guys looking for one for Home use. and where or how to find these??

Greetings . . .

Hey Twisted, these gizmos show up on ebay every once in a while:
SF-600
I think the last one sold for north of five grand - big bucks for most. The SF website describes their 110/120 model as 'economical'
I've never seen one of them on ebay.

IGOR, I am spectator when comes to this whole topic of flow. Your comments about a 70% intake/exhaust ratio 'sweet spot' are interesting - but I am not sure I understand the magic of this ratio. It's my understanding that this ratio is part of the overall engineering of the package: port volume, valve diameters and cam timing. I read somewhere that as exhaust port flow efficiencies are increased towards 80 and above, one can then choose a symmetrically ground cam. GM engineers on the other hand crafted a dual pattern grind on the 216/235/261 because they (in effect) designed the exhaust ports around a lower efficiency - 70 and lower - but balanced it with longer duration on the exhaust lobe. Back in those days they arrrived here by trial and error - cause there where no flow benches.

The other question I have about all this flow bench data that is out there (and there is bunches):
Stan\'s Flow Bench Data

The flow bench measures CFM on the intake and exhaust under the exact same conditions (10, 20, 28 inches of water). While this seems a useful piece of information it hardly matches the operating environment of these components. In a normally aspirated engine the intake valve opens into a vacuum created by exhaust scavenging (if there is overlap) and the receding piston. While the exhaust valve opens into a cylinder that is under extreme pressures (the earlier the timing the higher pressure - plus the effect of compression ratio).

With this big difference in velocity between intake and exhaust gases - how does one interpret flow numbers based on identical velocites?

best regards,
stock49

Yes i know their Not Cheap I have priced used Flow benchs. So I just had to ask That dumb question yeah know.I have even been to a few close outs(meaning shops going under) and even still a great arm and a Leg. But thats Ok I'll keep looking and paying a small rental fee more or less There is a shop near by that Lets me play from time to time when They don't have it tied up.

We bought and sold 2 SF 110 flow benches for $800.00. The SF 600 bench is a 28" @ 1 inch valve lift and are not cheap. We made our current flow bench and it measures flow @ 28" with the engine assembled without the pistons , rods and crank in it.

As much as we would like to replicate real engine conditions, the truth of the matter is 28" of water does not even represent flow at an idle, but it's all we can practically measure.

The port ratio can be influenced by cam timing and velocity of the port , but you have to start with a basic ratio of 70% exhaust to intake flow. The positive flow characteristic of the exhaust is the reason you only need 70% of intake .

All this being said, the flow bench is only a guideline tool. The dyno tells the story and ultimately the road test or the track test is true denominator.

I wish I could have a dollar for every idea that showed promise on a flow bench and showed nothing on the dyno. The one and only thing that has proven itself over and over again is the port ratio.

For instance, the Duggan head has a 45% exhaust port. In our early test days we got it to 60% and 80 HP showed up. We built 5 different intake systems during that same test period and we only hurt power. The best intake system was made clear by 40 HP , once a cylinder head with the correct balance was bolted on.

None of this is an exacting science, but for the best bang for your buck, get or build a flow measuring device and follow these gudelines. You will wake that engine up.

Just so i understand this right Your talking the exhaust is flowing 45-60% of what the intake is?? is this right??

Yes, the exhaust flow percetage is that amount of intake flow.

If the intake flows 300 cfm the exhaust should flow 210 cfm.

Ok that is what I had figured to start with But i just wanted to Double check the Question.And to help make it clear for anyone else who may have had the question.

Twisted6, just curious what is the best flow numbers you had gotten out of your lump port heads?
Thanks
Hank

Did the pics ever get reposted, or is there a link? I am really interested in looking at this.

Hank
with mild port work and NO epoxy to finish the Lump to the back of the head. We have been flowing at 245.2 and No lumps in the exhaust flowing at 177.6 with only mild porting Numbers also vary with different valves used.I will be posting some numbers in a few months of different head Flow numbers even a kirby Lump ported head, and All this has been tested On the same machine So we'll have Much better control On side by side testings.

Some will be with rasied Ports and Non raised ports. And as time permits I will also Be testing a Lump for the roof of the port along with useing one on the port floor just to see what happens. I also have a Port divider. That was used way back when.I have a true to fit templet and had a few made But never played with them YET. the days of digging/Learning will never end :)One of these years I'll have my own Bench which should save some time and money One can only hope right

Hi Larry, I can't wait to see what the Lump on the roof of the port does. I remember you telling me about that. When you do all this testing, do you have to take a bunch of heads to some facility somewhere or are you able to rent this flow bench thing? It sounds like a huge project to test these things, but very well worth the time.

I use one at a Local machine shop not to far from me.When the guy doesn't have it tied up I pretty much rent it from him. He has showed me how to use the machine this way I get to learn the machine itself Plus he can go about what ever he needs to do. Some times he'll just stand there and Watch what I have been doing with these heads Seeing He No longger does anything with L6s. Since I have been useing his machine I have done a few L6 heads for him/His customers. But hey what ever helps cut me a brake (in dollors) for me to spend time on his machine Is just fine with me. I just wish I had more time to spend on it.
(both ways Either my time or him having free time for me to use it)

Here is a good old hard to find thread. Too bad the pictures are gone.