Ok I have started posting Photos and some info. On how to install the Bolt in lumps & things you should know about Your Head. I started mainly with somethings You should know about Our chevy head. I still have Much to up load, and Pictures to retake & resize before i can get them up loaded. I hope this is a good starting point for many.I want to make this as Helpful as i can. I will even have a few picture of The Mike Kirby Braze in Lump port. I'll even have veiw from just about every angle I can get. bottom up,(valve face area) top down(looking down into the valve area( (short turn radius)face side (intake port) Yes i have been cutting up heads in many ways to show a veiw of all that i can. I'll even have pics where it will show No Valve guide boss to Trimed guides. hope this helps guys/gals
}[oooooo] so here is the Link
Looking great so far!
Twisted, Thank you for this huge effort, as most of us are totaly lost on this most important aspect of getting performance, whether street or track.
Hi Larry,
Would Lump Porting have any advantage to a 292 (at least .030-over) running on propane in a 4x4 '67 Suburban? Highway/offroad applications.
Larry,I agree with Newby. A heck of of a lot of work for everyone's benefit and it certainly helps the lesser skilled(me) to understand more of this process.Thanks.
Everyone I Thank YOU.
68Orange
It will help In all appilcation. What the lump does, It decrease The Port size But Speeds up(increases) the air flow. When The floor is raised by the Lump It then Makes More draw On the down side as The Valve Opens and The cyl.Draws Down In the chamber.But it all goes hand in hand, Like using bigger Valves, More lift or longger duration on the cam.
It's like the differences Between The Clifford Intake Over The Offey The smaller Offey will have Better low end Where as The Clifford will have Better top end.
so If you plan On removing the Boss It would be In best interest to install the lumps. The Reason to remover the Boss to start with was to try and Get more air Into the cyl.And one thing many do not think about Is that Both share The intake volume Because The port itself is Not Been divided So it has no choice but to share the volume. So When your trying to figure intake Port volume. You have to take in account Both the Valve areas in the Head. I know that some are still playing with The divided intake port along with adding the Lump. I have a set of port dividers That were Tried Many years ago. I may show these On the site Just for the Heck of it as well. Just so everyone can see what I am talking about. But after may Tests with the divider and the Lump It was found That The Lump really did Much Better. I think One of the reasons many have Cut and welded a divider In some of the clifford intakes Years ago Was to help speed the air flow back Up. Because The Air flow in our Heads/intakes Are in the center Their Is not much Move ment at The Edge Of the Runners So by adding in the Lump it is putting a squeez on the air flow Which In turn Speeds it back up. I guess a drawing Of this would also Be a little more helpful to understand.So this will be something else for me to add to all this.?
But anyway I'm going to do the Best that i can with all this info. and Hope that it will make a much better understanding to / for everyone, And save someone a costly head misstake by cutting into the water jacket.}[oooooo]
Larry -
your pictures are worth a thousand words! Thanks also for all of your tips and notes via e-mail as I have muddled through putting PES lumps in my 292 head. Your work is of great value to the rest of us. Thanks!
Again I have to Say Thank YOU to EVERYONE here for the replys & comments on this. I will be adding some more pictures this weekend Of Cut heads and I have One veiw I think is Pretty wild It is Looking Down On the head Into the valve area itself On the Intake & exhaust side. I'm still making cuts. was doing That again tonite on another head. Once I'm done with the cutting. I'll start On the Next part of the pictures Which is installing. Also will have some done with Epoxy, JB weld and even The Braze in. I now also have a few picture Of Heads Gone Bad you mite say. I even have one head where the core shift WAS bad and over sizeing the valve Was not a good think to do When a guy Had Never worked on one of Our L6 heads ( over sizing the Valves and did a Plung cut big OPPS on his part When Told Not to do it that way.)
I will let everyone know when they are up for viewing. hopeing this Helps everyone. }[oooooo]
Ps again Thanks
With all this 'lump head' business on late engines, how about GMC 302 heads. Has anyone done this kind of work on them?
Ed Pruss
Longmont, CO
GMC 302 and 270H heads have not been a subject for this kind of modification. The port design is different from the later sixes, and for all-out racing applications the various aftermarket 12-port heads have long been established as the better investment in money and time.
As Larry has demonstrated, "lump ports" are not a modification to be undertaken by amateurs. The process of installation is intricate and unforgiving of error. Design and development of the "lumps" themselves has been expensive and time-consuming--and, occasionally, controversial. Good, large-port GMC heads are growing increasingly rare, making failed experiments even more expensive, for a market that would never be significantly large.
God's Peace to you.
d
From what I have found Out and understand so far is that Epoxy or Jb weld has been used on them heads. I have not come across any bolt ins for them or have i heard of this.If I had a bad head of either I'd be happy to start digging into that as well. To see why? But their is the aftermarket which i'm sure is far better. Only my helping 2cents on this one Because I know Very Little about them Heads. But not afraid to learn anything.That maybe Helpful to pass along
}[oooooo]
OK I have up loaded the next round of photos a little more interesting veiw/s. And I have just a few more Before I get onto the next phase on installing the lumps. So if anyone thinks There may/mit be some other cut view/s they think I could add to this Just ask Please. Any And ALL Comments Are Welcome.
Ps. have I Missed any??
Thank You }[oooooo]
Larry, looking good! Any chance you can make each of the pictures a hyperlink to a larger version of the same picture? (I know this is a lot of extra work, but I found myself clicking on the pictures so I could get more detail)
Thanks again for the time and effort that you put into this. I should have a batch of pictures to send you soon on my lump install.
Ken
I have thought about that,But I have not ever tried to do so. But I will see what i can do. Or I'll just make one to go to a different Page with much larger Pics.And number them with out any Text info. But it will make for a slow loading Page. That is one reason i made them the size i did. So it would not take for ever to load.
But Thank You.}[oooooo]
Ps. If there is a pic you would like to have right now I can Email it to you Just let me know.
I'll be happy to send anyone of them.
Ok Just so you do think I have stopped on this Or on the updating of pictures . They Lost My pictures so I have to Reshoot all The lump port work And the Lumps. Sorry for the Delay. Looks Like i need to also USE my DIG.cam Just Incase For back Up this time. Just Bare with me on this.
Thank You. }[oooooo]
OK a long time in the Making Where has the past year gone to. Well I'm hoping to get all the new photos resized and Up on the web this weekend or Very first part of the Week. Along with the with these new photos Will be Photos with the Raised PORTs. The Port ceiling has been Raised .100 Photos Showing with and With out the Lumps. Also I will have side photos With the Lump installed and Down Looking onto the Lumps, Along with many Other New pictures.
Thanks For Waiting on me with all this.
# 3220 }[oooooo]
hello...good to see talking here about raised ports....Good job....what PES did (I will share this -the head on page 100 of Power Manual looks ALOT !!!!! Like a PES Head.....mmmmm VERY interesting.....)and what i have learned is raising ports is key on BOTH intake and exhaust-NOT a lump-and this is more raising MORE than .100....but .100 is better than nothing....
here is something to think about-
1st-braizing is ok but VERY limited in what can be done to a cast iron head....
investigate what can be done with cast welding-NOT the old way but the newer technology....
even considered this?...... port intake and exhaust ports on port side (turn head upside down) till you hit water jacket...open up top of port-fill in with CAST then ....then make port go almost straight down in head-this is key.....and head STILL flows water....
then fill chamber-VERY small .....
what do you think about divding ports on Intake side? ....more interesting ideas......goes against all we were told, RIGHT!!?!?!?!?!!!
this has been done and will be done more.....
Its good to see movement ahead in head work here...Good Job....
Good For you ,I'm Happy to see that YOU approve Of this Not Like It matter to Me I'm the One Doing it. And taking the time to get the Photos. And Put them up on the Net.Again No thanks To you??? And Their was a Reason For Only taking this Port up .100. I Know it can Go More.
And as for Taking a Port to the Point YOU're Needing To add Back An REShape It Pretty Much a 100% AGAIN IS NOT for The average daily Driver ON a Low Budget Build...... I KNOW FOR One I'm Not about To spend That Kinda Money OR The Time For a DAILY Driver. That's Why I don't Bring it up.
But Yes I do have a Head Cut Out for FULLY Raised/Reangled PORT.(also one with the Boss still in the head cut out around it. And No I do have Photos TO post and I may Not ,Again Not SOMETHING For Everyone as a Daily Driver!!!!
NOW Secondly Nobody said The Head wouldn't flow water Once the Port ceiling has been Cut out and Refilled. Of course it will flow It Just Changed HOW IT will Flow The Water around The Intake PORT.
And as for The dividing the intake Ports I think You For Got Who send The Templets to Jack Somers a few yrs Back I did. I Not ONLY have the Templets I have The Dividers as Well..... And all
this was Done Way Back...... in yr 2000 When I
first spoke to Jack Somers and I sent them to him
So to me not more interesting Something I already
Knew. So If One is going to Take the Time and
MONEY to Cut Out The whole Port ceiling YOU may
as well go The extra Mile and divid the Port And
be even closer to a 12 port head humm....Interesting Now isn't IT????
Sorry I don't have time or Money to sit on the
Phone Or to run to every Top Head /Engine
builders shop.
And I'm Sorry it took me a yr to Redo all The Photos. BUT ALL THAT I"M Doing I'm Doing ON My
OWN.
SO---
Now My final word to You. If You Don't like what
I have Or Had to say Then Stay Off MY POST.
UNLESS YOU have something to Put UP THAT YOU DID
(PHOTOs) Not someone Elses. And I know It's a Good JOB I'm The One DOing IT and I get My Thanks From Many.
So Now To everyone ELSE SORRY BUT Thanks For Letting ME VENT one MORE Time.And Thank You
To Everyone
M # 3220 }[oooooo]
ps yours IS?????????????????
hello...again I was trying to be nice and was attacked ....but what else do I get here....
Read my Post again-it was basic concepts on the head-do you think I was attacking you as you attacked me???? I tried to offer good comments I thought you may want to know...But AGAIN I was wrong.....
but again I compliment you on your work...but remember where the Intake plate idea came from- see, you didnt support another fellow Inliner-PES and his research but slmammed him and you dont support my research and slam me- but its ok....
Bottom line ,you copied the Aluminum Intake Plates from PES....
I just try to help and offer solutions that are out there and many know...
its just VERY limited here.....
as far as dividing ports, it only helps when you raise the ports-not by keeping them in the same place as a stock head- I Post this info for those that want to know and are shocked at what can be done-and be amazed how we have been mislead.....
again I TRUELY was being kind to you but you attacked me...
I truely thought you might like my compliments to your comments/Post on head work- again its about the head -NOT YOU , ME or anyone!!!!
as far as having time, I have limited time myself-
I just want to find out what really works-no matter how MUCH time....
Dont you know the Kirby head is really the Duggan head? Why give Kirby credit for Duggans head? dont you find it interesting that the Kirby aluminum head has raised ports? Its cheaper to raise the ports on a cast head....why didnt he ever do it? Think PES ever tried to work with Kirby? Again, see page 100?
its too bad you want credit for the Intake plates- you should support PES
Do you have a head YET with plates in that u are racing?
As long as you are happy ,right...AGAIN I was wrong Larry- I thought you might be interested in my comments- you are limiting yourself and others-is that what you want? Is that what this Forum is for?
Lee First Off I never SAID WORD ONE about PES So DON"T Go Putting words In that are NOT There to start with. And as to taking It kinda?? personal Yeah Maybe So When I see CAPs an ??????????!!!!!!!!!.............. All the Time
Then Yeah I'm going to take it that way.And As it has been said Before YEah Your Comments That is all you come here with. 1 ONE Time did you ever back-up what you had to say an that was the Crank stuff. Now as for the shape an Size of mine No not his Mine Over all Looks????? yeah maybe so But Then One Could say He copied the Braz-in BUt Again No one said that EITHER and as for The Duggan Head that was a Joint thing?????(everything i ever Read was Duggan/sissell Head) I Don't know FOR 100% I wasn't There. Now as to THE NEW Kirby HEAD IT's Nothing LIke THE OLD DUGGAN HEAD I Know I HAVE SEEN Both And They are Nothing alike.
And I'm Not Bashing PES but hummmmmm But I don't recall seeing a banner/add in The 12 port OR on the Web site supporting OUR ClUB and as for supporting him I did I sold his lumps till I was done with my own. And Besides I wasn't paid to sell his stuff So I figure I gave the support I needed to.And Besides THAT I have Sent Many people His Way and Still Do from TIME to Time.
PES ever tried to work with Kirby? I have No clue
And It Realy don't matter to me Or Is that any of
business to worry about.
And from time to time You've been asked to show
us something and what do you do???? just make more comments. And Like I have said to you More then Once. You want to send Me the pictures I'll post them Just Like I did the Cranks and YES i gave YOU The Credit DID I NOT?????
Yes I have a Head with the lumps in it.(MINE) I'm also working on Other heads And another Intake.No I'm Not Racing right Now. I have seen THE same car run With and With Out the Lumps 2 10th Yes is a Lot But Not something I'm to worry about writeing Home To MOM about I have seen Better Then that Just Changing a traction device. I may Never end up running that head I may End up just simply running The Other one I'm working On So your point would be?????? And the Head that Now has the .100 raised port Will Be run on The Same Motor Combo That has Ran a Stock NON Lump ported to a Kirby head. The car Runs ETS Like Clock Work SO what a Better Place to run That Head On. I don't Need my car yet to see what My work is
doing.I have Been making to many Changes On My Car and Motor Combo TO know If the Head did anything. So why would I come out and say It did This & This, when to many Changes have Been Made.
BUT trust me When The car Makes another Pass I'm Sure You Hear about It
As to limiting myself???? and Others???? i don't thinks so. And yeah I find Your CommentS! interesting but then I don't half start someting and drop it. JUST like your Dist.Issue/cast welding-NOT the old way but the newer technology.... You Make CommentS! To get One/s Interested In YOUR
Comments Then That seems to be the end of it and YOU run off Till YOU Feel THE Need To Make
Comments Once again. And I did Not Say you Was Wrong.
So If i have seemed to have Miss read Your post/Comments/compliments Sorry Have a NIce DAY
PS What makes You so Sure I didn't Make My Lumps From Kirbys Braze-in Seeing That is what I was after to start with NOT PES
M # 3220 }[oooooo]
I must say Lee, if you think you are 'attacked' then maybe you should stop with the thinly veiled derogatory and condescending comments you have been directing at Larry over the past several years and stay off his posts. Frankly I'm getting weary of this "victim' scenario also. Youv'e been very helpful in other areas, and I appreciate that greatly, but please, enough already!
i have a quick question...i thought separating the intake ports into two separate ports was not good for these heads?
and if is is good how would one go about doing it?
Separating the Ports Wasn't a good thing IF The Port was left down low so was said.That Is Why The Port was Raised Up to a Point That You realy Kinda Needed to cut the ceiling out of the Ports. Back in the 60's/70's there was a article That went into Very good detail. For many things, One was a Templet to divide the ports Which was a TRUE Useable templet. I made these Templets to Use at one time back in the late 80's early 90's
but i never got around to useing them,do to the LACK OF INFO And was told By many at that time That They/it didn't realy work and The way was to do The Lump port. IT seemed many yrs back No body realy wanted to share Or Talk to much Over the Phone If you wasn't going to be BUYing something from them Or would One Pass you along to someone Who Was willing to Talk to You.
But anyway The Top/ceiling Of the Ports need to be removed TO Get The Straightest/Down angle into the Valve area But Welding/filling of some sorts Needs to be done.But also Keep in mind Then The Floor should also Be Brought Up and angled along with it. But NONE Of this was ever Much of a Topic Till the Power manual came out a few yrs Back. So Now that More start to hear Or Learn about this Type and Other Ways To Improve The Air Flow for The Chevy L6 head. And as Some come to find out that some Or at least alot of this Type Of Head Mods are Not for The average Back Yard Builder Or some one On a VERY Low budget. And Making a Port divider Like That Of the article Is Lot more time consuming then to add a Lump. One other thing I need to bring up Was also the Fact That They also CUT the Intakes down the Middle to Fully divid it as well.They Even divided it Under The Carbs right into the intakes. Or they Just had Home Built Intakes Their is No after market intakes that are divided OTHER Then Maybe Mike Kirbys But That's for his head.
And Again THE BOSS was or Needs to be Removed to make/install The divider. Maybe when I find a extra half a second or so to see about digging these Back Up maybe?? I'll get a few pics and Post them??????????
i hope you got answered and Sorry for a Long Wind.
#3220 }[oooooo]
That cylinder head on pg 100 was a customers of Mike's & was supposed to give him feedback on the cylinder that had the raised ports.... but he never let Mike know what the improvement or outcome of this highly modified/expensive cylinder head.... O--- wellll
Hank
Come on guys, endless blathering about this lump port vs not is boring. Has anyone ever done a real world dyno test on a non head and then a lump port head? I am building a 292 for street and want to find out if the cost of lumps will give me anything I can use in a daily driver. I don't want to spend several hundred dollars on something that will only help in upper RPM ranges.
Dear C32;
I don't know much about them, but they (custom heads) are really for the racing gang. What everyone wants there is, another .5 second +++ etc.
A mildly reworked 292 head will work just fine for a passenger car. Don't forget that engine was designed by GM for hauling heavy loads in big trucks. A 302" with an EFI & 10 to 1 will 'smoke' most V-8s, so; "don't worry be happy".
John M, #3370...
Their is a gain in the Whole RPM Band Not Just the upper rpms. Right from .100 to .800 lift cam show a increase in air flow. So yes they would help a daily driver.
NOW THIS GOES for Both Race and NONE race app. If you have never run The Motor with and with OUT The Lumps You Personaly would never realy know the difference. It's JUST LIKE setting a cam Up
AT TOP DEAD 4degress before Or 4degrees after UNLESS You REALLY Ran it Both ways and REALY!!!! know the feel Of
That MOTOR YOU Wouldn't EVEN know THE DIFFERENCE EITHER!!!!!
Now If you'd Like to PAY for a SET Headers to Run on a DYNO and The COST.I'll be more then Happy to run a test for you. REASON for a set Of Headers Is The Motor IS RUN SO HARD the PIPEs TURN CHERRY RED and ARE pretty Much toast AFTER That. But there has been enough On track test That show the Difference for The one that want the Lumps See The difference So No REAl Need to run the Motor on a dyno.
And I have installed Many sets into Daily Drivers with Mild to semi Wild cams. And No Body has come back and said Hey remove these they don't seem to be working.
#3220 }[oooooo]
chevman32
If you want to make a better daily driver & get better fuel economy the lump ports are the way to go. It will greatly increase the intake velocity which in turn will give you more power better milege & better throttle response.
Remember.... You can always improve cylinder heads, & that is where you make your horsepower & torque.
Goodluck on the several hundred dollars being spent.... it will be worth it.
Hank
Some people may disagree with this but here goes:
Any inprovement in cylinder head and exhaust system flow and velocity will increase torque, up to the point where the largest pressure drop is the stock carb and intake.
Better head and stock cam is way better than stock head and big cam. If you improve the head and increase the cam slightly your miles ahead than stuffing a big cam into an otherwise stock airflow system. Drivability suffers.
Twisted -
See if this will help on posting your pics.
Go to:
http://imageshack.us/ If you store your digital pics on your computer, then go to 'Browse' and find your pic.
Click 'Host it'
Then you will have serveral options on how.
If you click on the 'Thumbnail' you can copy the link and post it here and we will see a 'thumbnail'
OR
you can click on the link at the bottom that says 'direct link' and copy and paste it here and we will be able to just click on the link to see your pic.
You may already know and do this, but if not, check it out.
I am just starting a rebuild on my 292 and am checking your post here.
Thanks for all the info you are providing.
Timmer
Twisted:
Here is an example:
Link to my truck:
http://img28.echo.cx/img28/6018/1mvc873s7un.jpg and a thumbnail: (click on it to enlarge)
Timmer
Nice truck, where are you located?
Ed Pruss
Longmont, CO
Thanks But I don't need a site to post. I already have a web site.
#3220 }[oooooo]
Just a little up date to what has been going on. I have been workin gon a Whole NEW site.I have also een working with some new video editing software. With the Hopes of having a video of the installation of the Lump from point A to point B This sofware will also Able me to make a CD or DVD.I'm thinking as a Slide show.Of the steps. If anyone has as any imput or comments You can Email me with any. The Site I am Hoping to have Up and Running by the end of July How ever The Video/Slide show may Not be.
Thanks
#3220 }[oooooo]
Seeing that There has been complaints about my Posting a link to my web site On the Head info.
The Postings will be removed. Sorry I slaked Off any My Duties as a Paid memeber and Board Moderator. Won't happen again have a good day
#3220.
Ps who ever it was Could have said something to me I would have Removed with out a issue seeing this Topic ran Over a Yr. with Great interest.
But no problem
I will also ask that The Chat room Be removed so that there is No longger any other Clash Of interest.
For whatever reasons,real or imagined,for that decision I hope you will not be discouraged and keep us informed with all the tech info and help you have so unselfishly given to anyone who asks.With over 1800 posts I,d hardly call that slacking off. At any rate, dont give up on us cause 99 percent aren't gonna let that change a thing.
well with that many posts one may think i live here LOL
#3220 }[oooooo]
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...
300
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.
