Inliners International Forums General Discussion Blown and Injected turbo 292 write up

Thanks for the kind words Josh. I think the shorter lump with a divider can help. Its might be a balance between give and take like you said.

I would need o cut up a head to get some dimensions close whoch i would really hate to do hmmm how to make shorter lumps while still having a good short turn radius also i could build the keeper for the dividers into the lumps that way once they are bolted in all you would need to utilies is the idea of the pipe plug on top

Do you remember the saying what comes first the chicken or the egg.

This is what the port argument is about.

To make power you need air and fuel, the port needs to work equally well on both aspects.

I have found the HP level you want dictates the port you need.

A stock port is not good for much, this is why Kay Sissel made the ingenious Bump Port. It helped the velocity and direction of air flow to the back of the valve, therefore more air flow.
This arrangement worked to a point of about 400 to 500 HP. On a race engine. If this is your goal use a Bump Port. But at this HP level the undivided port starts to show fuel distribution problems.

If you want to make more HP. You must switch to a Kirby Sissel 12 port the best bolt on head on the market ever. All the older versions of a 12 port were not any good in comparison to Mike's head.

Back in 1985 I had a bump port head with my turbo worked great until I tried to make over 500 HP. Then all my issues started, Cylinder #1 and #6 would run lean and could not fix them without making all others too rich. I stuck with the stock head way too long trying to fix the problem, to no benefit. I divided the stock ports but had to up the boost to compensate for the poor flow, it just made too much heat to try and control. Even tried a 12 port from Brazil GM had made, just too small of ports like my divided head, worked a little better but not enough to make good power.

Finally bit the bullet and ordered the Kirby head, wished I had done it 20 years ago.

P.S. Back in 1965 we raced a 292 gasser that ran good for it's time with a Hilborn Injector and a divided head not a lot HP as today, but did that baby hit a note !

Just ask anyone today what would happen if you cut the dividers out of a chevy head and they would look at you as if you were nuts, people tried it in the early 60's just ask some old guys.

It does not matter if you use a carb or injection, it's just the injection is so precise it shows up more as a driveability issue.

Josh, here is a picture of one of our professionally ported brazed lump heads. The port dimensions are 2.540"W x 1.625"H. This will give you some idea on how much you can open up the intake ports to reshape and resize them to compensate for a divider.

Turbo-6 thanks for the great story and lots of info i am only looking to make 400 as a sissel street 12 port is probably rather expensive this being said i already have a good amount of money.. Well say invested in the head i already own plus parts that match to that head like the spa turbo manifoldand such hmmm have a bit of thinking to do on that anyidea what it costs to get a good 12 port head now adays? And i' just looking for good air flow and even fuel distribution thats why i was thinking a divided multiport injection for the turboed 292..

Scott that is a really nice looking lump port i just have the bolt ins with stock intake size now milling done ..

Honestly you guys

How far must one go for decent flow high hp street 292 with good milage? I know the 12 port is probably the best but ban for buck wise whats every one think

Also if i went that way how hard would it be to turbocharge. Would i still want to?

Ideas and thought are always welcome

Turbocharging a 12 port is no more trouble than a stock head.

Since you have a bump port and a spa exhaust.

With what you have just add a thin divider to the bump port head 1/8 inch wide to the shape of the port tack weld and epoxy seal to the port which can be removed anytime you need to remove the head just a very very thin ribbon of epoxy to seal is what will help. Also if you can divide the intake port this will also help, you want to keep the cylinders from effecting each other so the longer the better.This setup should be good for 400+ HP

Thinking about your bolt in bump maybe you could weld the divider to the bump before installing it, but seal it to the port.

Maybe the guys making bolt in bumps may think about this as an option the divider as part of the bump? Nope this won't work because you need to bolt down the head. But you could add a tube to the divider and bump and use a normal bolt or stud, I have done this in the past it's just the tube has to be the exact length to work. Also I have bolted the bumps through the port side, then they can be removed with no trouble.

Just food for thought.

So with out the head being milled any, a divider will work with the lump i stalled

Do you have any pictures of the installs or attempts you have made? If so i would really appreciate those

Thanks t 6 we could deffinatwly get this figured out. Together

The problem with the current bolt-in lumps is that they are designed to fit a stock unported intake port. So adding a divider will naturally require the ports to be widened by some amount and even possibly raised to compensate for the narrow window that is created by doing it. Also maybe a completely new design lump that is also a little shorter. The last style of brazed in lumps we raced was shorter than the bolt-in style is already, and didn't have a teardrop face shape and produced the most HP and airflow gain over the previous ones, so there is a lot of upgrading and updating that can be done to them if someone really wanted to make a better mousetrap.

Hmmm i would deffinately be interested in horter lumps but anyone that does head work seems to be east coast? I have to see the freight ticket from az to georgia hmmm but then againn haha

Josh,

As I was working today (day dreaming) I remembered years ago I had a bolted in divider with a stock port just opened up a little, no lump port, I used a normal allen bolt for a head bolt. The divider had a notch to clear the bolt head and on the top I had a notched solid disk, like a washer without a hole but a grove in the bottom to hold the divider and a pipe plug to hold all in place. worked good cheap and easy to do.

If you have a stock head with the post still in the head, just make a 3/16 divider to go behind the post tack weld in a couple of places . Then a piece 3/16 X 1/4 to go in front of the post epoxy all in place and your done. This is how I did my last head before the new 12 port Kirby head.

I will try and post some pictures of this head and other dividers styles I have run in the past.

Thanks for the insight i would love to see pictures i will be eagerly waiting

I was also wondering if i could take the lump put them on like a plane sander and shorter then then maybe notch a grove 1/8" all the way down the middle that it could slip into while still going over the bolt i'm not very talked at drawing or explaining but maybe that makes sense ... I hope lol

Yeah, shouldn't be a problem. And if you screw it up, tell Tom you have a "defective" one and to send you another one!

So if i shortened the lumps woul i still have to mill the port wider and taller?

I guess thats kind of loaded because not much has been had feom this subject i guess you could say but basic port volume should answer the question right or no??

Im trying to remember how thick those are. I made some billet ones before for a race ported head similar to the brazed ones. But yes, shortening them up should help to a degree, but keep in mind that these lumps will only fit the stock port width, especially at the intake port entry. But it might benefit to gain back some port area that is lost with the divider. Start with shortening the lumps and making the divider and fitting it into the port and see what that looks like first. Then post pics and we can ponder what needs to happen next.

The stock head with the divider as I stated above had a big enough port to make over 600 HP and you only want 400 HP.

Remember the original idea of the bump port was not only to make a short side radius but to make the port smaller, Look at a stock small block chevy head at the push rod area it's not much bigger than a stock divided inline head. You measure the smallest area on a port for the air speed on a head not the largest.

This modification takes about 2-3 hrs and your done. No head bolt issues, and that was with 1.94 intake valves. No porting just a stock head with the bigger valves and dividers.

With a turbo that's all you need to make 400 HP at about 12# boost.

The turbo more than makes up for any port design, just do it, and you will be happy.

So with the lump and port stock sizes with a devider is not to small of a port to run that way?

And be effiient i should say while still creating horse power i have 1.94 in and 1.6 exh valves so that šould help the situation with aftermarket cam and40 over

He's saying he did not use lumps on his divided port head. He left the bolt bosses intact and added the divider behind and in front of the boss. The bolt boss is going to be a much larger obstruction in the port than a lump will be, so from what he is saying, the lump may be fine "as is" for your projected power level. However, after you drive 400 HP around for a couple of weeks its going to feel like a golf cart and your going to want more. So plan ahead, instead of for the here and now.

Haha gosh i hope my truck doesn't feel like a golf cart well if i run straight lumps i guess the mixed match is the lumps with multiport injection ? The plot thickens ....

I think i should research short turn radiuss and see whats up there maybe being blown makes that shape not matter? I believe thats been said before

You'd be surprised how quickly you get used to your power and want more of it.

I think for an injected build a divided port is going to be more beneficial than a lump is going to be because you eliminate the fuel robbing concerns between adjoining cylinders. And obviously, Harry has made some good power without even using lumps at all, as have many other racers past and present.

The post is not really an obstruction since the wall across from the divider widens out as it passes the post.

Any way how do you post pictures on this board?

Do you have a photobucket or imageshack account. You need one of those or similar to be a hosting site to post pics.

Oh goody picturess i think i'm going to divide the ports ad remove the lumps i'm stillgoing to ty an shave the lumps down and see what i can do or i might just sell them for some spare cash i don't know yet though decisions decisions

Might even keep them

Here are some pictures of the divided port. The first picture is the bolt in components. The following 3 pictures are how it is epoxied into the head.

They're not showing up. You have to create a link through a hosting site.

Are you sure they show when I login.

I can see them OK too.

T-6 Thanks for all the tech.

I can see them they look fantasic really nice work t -6 looks really smooth. And pictures of the bolt it one in action? Since i already have the bolt boss removed and what did you ise to epoxy them with? Also you said you welded them? With a mig welder?

Ok I can see them now. Looks good.

Welded with mig 2-3 tacks per side on head with post.
Old style bolt in not welded or epoxied, could epoxy if you want just a little to seal.

The epoxy is a marine brand that the area head porter uses but can't remember the name, will try and find out for you, I know it's very expensive.

Welded with mig 2-3 tacks per side on head with stock post.
Old style bolt in not welded or epoxied, could epoxy if you want just a little to seal.

The epoxy is a marine brand that the area head porter uses but can't remember the name, will try and find out for you, I know it's very expensive.

Now does the bolt in lunp have that flare in the back like the two piece? If so how does one go about makin the flare in the rear also is there anything else holding the divider in besides the grooved washer and does that washer fit down intothe hold that the pipe plug would go into?

If you had and pictures of that i would love to see

Thanks t-6 for all the help and tech info can't wait to build these, hopefully they look as good as yours.

The bolt-in lump doesn't go all the way to the rear of the port wall, they only stop about 3/4 of the way in. There are many ways to improve the flow on the divided port idea. The slotted washer fits on the topside of the divider in the original head bolt boss and the screw-in plug holds it in place. My friend Darren's port dividers were much thinner, and this ports were already opened up wider for racing. They were already over 320-ish CFM before he divided them. There is a lot of untapped potential in exploring this.

Oops sorry scott i didn't meanti say lumps i was asking about the bolt in deviders

Ok, no problem. I also think the divided siamese port head will have the ability to greatly exceed the potential of a Brazilian 12 port head because the ports are already larger than that head and can be further enlarged and may even give a bolt-in lump port head a run for its money. I may have to pull one out an do some testing as well. Im fixing to start a turbo build, so this may give me an option to consider.

I made a pattern and had the dividers cast a long time ago.

You could take tin and make a wing shape in the valve pocket it would look like a Y from the top view this would help register it in the port.

If you have a lump in your head just take a thin 1/16 scrap of metal, after the head is installed shape it to the port and let the plug at the top of the old bolt boss hold it in place maybe put a tang that registers in the allen head. You could even let it stick out of the port and extend into the manifold. Anything will help it's just the better the seal the better it will work.

Just curious what did the head flow after the ports were divided?

Having a head that flows 320ish cfm, how good would his head work for a daily driver?

Thanks.

MBHD