cleaning up the slant six head
I plan to do this work myself, I will be posting pictures along the way and asking for corrections suggestions as I go. I think you and I will have a pretty good understanding of the basics by the time I am done.
Tools and equipment are no issue for me but its easier for me to post pics which I will be doing after the next couple/few weeks.
Well, I may be the "Bill" that Ed alluded to earlier, and I am known on this forum as a motor-mouth (motor-keyboard?) because of my inability to contain myself, resulting in my penchant for writing long, rambling, wordy posts when I don't ACTUALLY know what I am talking about.
Apparently, that gets old to some people, because the management here got enough complaints about me that I was told by the higher-ups, to give it a rest, or face suspension of my account.
So, I did.
The powers that be have not sent me any more "directions" on how to manage my posting on here, so I must be doing better.
Anyway, I had stayed out of this thread because it dealt with something I wasn't particularly interested in, nor very knowledgeable about (so, I had nothing of interest, or value, to say.)
But, since Ed (805Moparkid) asked (well, sort of,) I decided to give it another shot.
To begin with, I am a virtual newbie at slant sixes, having owned my first one for only 4 years, Secondly, my interest is in forced induction as regards this engine, and I am equally-new at that, too. So, I am far from an expert. But, I have learned a lot in the past 4 years on FABO, from reading the posts, and on the "ORG." forum, so that, along with many years of conventional V8 hot rodding, and this has given me at least,
some perspective.
To that end, I have come to some inescapable (for me) conclusions. I dug up an old post that illustrates some of them. This is from a few years ago, and is pertinent to this thread, I think.
To wit:
"As I immersed myself in the postings about /6 performance, and videos on You Tube of various /6-powered cars, I began to realize some things about these slanted little devils that had escaped me for years. Here's are some things I had missed.
In a general way of looking at the /6 archetecture, it says one thing in a big way: This cylinder head may be a perfect head for a 170 cubic inch engine, but trying to make a normally-aspirated 225 breathe through those same 170-sized ports is a job for Superman.
What I mean by that is, the ports and valves, as manufactured, are just too small for the amount of cylinder displacement they are asked to feed in a high-performance 225 environment.
The /6 has 225 cubic inches. If it had 8 cylinders it would be about 300 cubic inches with the same-size (37.5 cid) cylinders.
Just for comparison purposes to show what size these ports and valves are, the 1967 Chevy Z28 came with 302 cubic inches (virtually the same size cylinders as a 225 /6 engine,) and their intake valves were 2.02" in diameter (slant six "
oversize racing valves" are 1.75", or fifteen percent smaller than the "stock" 302"-Chevy valves, and the 1.6" Chevy stock exhaust valves are still 6-percent larger than the "oversize
racing" /6, 1.5" exhaust valves. To say nothing of the stock /6 valves...
The Z-28 Chevy ports in the head are commensurately larger, so that the flow numbers are a pretty good match for the valves, in their stock configuration.
The bottom line is, a mildly ported (302) Chevy intake port will flow close to 280cfm to feed the same size cylinder that the /6 is trying to fill with that 1.75" valve that is in a head, that after porting, will flow 220cfm, absolute max...
The slant's big, heavy, crankshaft doesn't help matters, especially when winding up 1st gear.
So, here's what I have learned:
I watched videos of the chopped, 2,350-pound "MadMax" 1st generation Valiant with a normally-aspirated /6 running 11.50s with NO power adder of any kind.
That car is incredibly fast and quick (watch how it hooks!!!)
I've never seen anything like it!
I didn't REALIZE that a normally-aspirated Valiant or Dart could run like that!
I happened onto two more videos on You Tube that opened my eyes even further.
There were two videos of turbocharged 225's that blew my mind. Tom Wolfe has a 3,300-pound '70 Dart that has run 11.02 with a new 225 motor (at 122 mph), into a 15-mph headwind, while another forced induction racer (turbo66Valiant) posted videos that showed his pristine '66 Valiant running some 10.70's, which is about a full second quicker than the already fast, but unblown, Mad Max car.
Not to belittle the Mad Max car, because it's stupid fast for its combination, but that '66 Valiant is I believe, 500 pounds heaver and a full second quicker. And, its running a 727 (heavy) transmission... probably about .2 and 3mph slower than it might have been with a 904.
So, what did I learn from all this???
Not so fast; I said I was a slow learner, and I surely am...
I did a lot of research about the /6 motor, and one thing stood out:
It's built like a brick pagoda. Its aluminum ancestry seems to have left it with an infrastructure that has no equal in the modern automotive world, when it comes to strength and ridigidity.
Remember that big, heavy, crankshaft I was carping about awhile back?
Well, I found that the early models are forged, have internal balance, and bearings the same size as the 426 Hemi.
As close to an unbreakable stock crank as you can probably find; it's short and stout!
The block's cylinder walls can be bored over .100", the head can be milled that much if need be, (over .100") and the top of the block is pretty thick, but I have no reliable numbers for that. I think it's thicker than half-an-inch.
What all this means is, unlike the Buick GN turbo motors which (the stock stuff) don't seem to want to stay together if the boost goes much over 20-pounds, it's an open question as to just how much boost one of these /6 motors could stand, if someone really got serious, because K-1 is making some great-looking forged rods for a 225, and forged pistons are available from Wiseco in a .065"-overbore, creating a 234 cubic inch motor.
Shaker223 and turbo66valiant are probably generating over 500 flywheel hp as we speak, but can 600 hp be far behind?
It's not necesssary to build a 500hp motor to have fun with a turbocharged /6.
One of Tom's early engines was pretty much stock with a Buick turbo stuck on the bottom of a stock exhaust manifold, and it went high 12's, in a 3,400-pound car.
The possibilities are endless!"
That kind of sums it up.
I was trying to point out the fact that, given the handicap of the original cylinder head, no amount of port or valve work, is going to make possible the kind of power-increases we seek in this 225 motor.
Ed (805moparkid) has a well-built '68 Dart that he has spent considerable time and money on in an effort to achieve impressive quarter-mile times. it has a minimal amount of "lightening" (a fiberlass hood, etc), and the usual hardware upgrades to its 225 slant six; I think it's bored, has a fully-ported head, with bigger valves, higher compression (I don't remember what the exact figure is,) headers, a 4-bbl carb and manifold, a re-curved spark-advance, a deep-geared 8.75" rear end, I believe, sub-frame connectors, a radical cam and some upgraded valve springs.
It is a well-built car, worked on by a guy who obviously knows what he is doing.
It has yet, to make a pass into the 13-second zone. Low-14's are "it," for now... Ed, correct me if I am wrong about that, but that was true the last time I heard a time on it.
My friend Tom Wolfe ((Shaker223 on FABO) took his
bone stock 1970 Dart 225, added a 4bbl manifold, a 4bbl carb and a junkyard Buick Grand National turbo and went 12.98-seconds @ 102mph in the quarter.. No other changes; the stock head (with those tiny valves) had never been off the 100,000+-mile engine.
That's a full-second faster than Ed's car.... with a stock short block, and gearing.
I am not belittling Ed's efforts here; he's done a really nice job with that car and hasn't made any mistakes that I am aware of. What he's accomplished is what any competent mechanic/hot rodder could expect to accomplish with the same assortment of parts.
It's that ^%$#@&*%!!! cylinder head!
Even ported to the max, and with oversize valves, it is a bottle-neck that cannot be "fixed."
Unless...
A turbocharger makes an end-run around all those breathing problems.
Make no mistake; turbocharging one of these engines is
not an easy task (but, it IS relatively cheap, compared to trying to get the same amount of power, naturally-aspirated.)
But, it's getting easier all the time, because of the burgeoning market in turbos and related equipment.
The fact is, you can make an easy 300 horsepower with about 12 pounds of boost on (good) pump gas, and still use your stock pistons and rods with good reliability. I would recommend two things; a water/alcohol spray unit for the intake charge, and a GOOD, wide-band, data-logging 0-2 sensor (such as sold by F.A.S.T.) for tuning the mixture.
That is the single most important piece of hardware you'll need, and to try this without it is.... just not something I would recommend.
A two-barrel carb on a Super Six manifold would be ideal.
A PISHTA-designed J-pipe turbo-mount would make headers unnecessary.
I honestly believe that even with the learning curve involved, the time spent chasing parts, and the time spent designing the layout, you'll still be money and time ahead with the hairdryer setup.
The advantages are numerous' the engine will make more power than a stock 340 V8, it will have excellent driveability (smooth idle and a lot of low-end torque,) LIKES a 2.73:1 axle ratio, both for performance and the highway, (so an overdrive is not needed,) it's quiet... the turbo homoginizes the sound waves, so you probably won't even need a muffler, and your stock 8.25" rear end is fine for this. A stock torque converter is also perfect for this app.
Opting for a normally-aspirated engine with THAT (170) cylinder head just seems counter-productive to me. You can easily spend $1,500.00 on porting and big valves in that head and still end up with less than 300 hp.... Ed had that setup maximized (as far as I could see,) and that was his case...
Albert Einstein couldn't figure out a way to put enough air through that head (naturally-aspirated) to make decent power...
All the hand-wringing, and brainstorming to get the best-possible breathing out of it is just a monunmental waste of time when a hairdryer is so (relatively) easy...
You can't make a silk purse out of a sow's ear.. and that little 170-designed head
IS a sows wear on a 225.
But, there's away around it.... :cheers:
See; I told you I don't know when to shut up...:oops:
