whitepunkonnitro
Well-Known Member
"Semi Hemi" is one of the nicknames applied to the Big Block Chevy. Went from Mark V Mystery Motor to Porcupine to Semi Hemi. Later on went to define all canted valve wedge engines like the 351C.
225 Hemi head
- Thread starter rp23g7
- Start date
-
cjh
Well-Known Member
The \6 cross section looks/shows to have a "wedge" combustion chamber:
Yes, they are a wedge.
Standard on the left, shaved on the right.
Yes. The slant is a wedge engine, but we weren't talking about the slant. We were talking about the Hemi Six. Completely different animal.
The \6 cross section looks/shows to have a "wedge" combustion chamber:
The polysphere motor predated the big block Chevy by several years (1956 277-1963 G.M. "Mystery Motor") and utilized canted valves set at different angles, a first for OHV V8's. It could be said that that first Mopar "A" engine was a "prototype" for the later Big Block Chevy. That A engine was an outgrowth of the previous Hemi motor; an attempt to retain some of the advantages of the Hemi combustion chamber, without the expense of two rocker shafts and such a really wide cylinder head. It was the first "semi-hemi."
cjh
Well-Known Member
Yes......I have a 245 Hemi 6 under my house in pieces.....a little spread out though.
Charrlie_S
Well-Known Member
Charrlie_S
Well-Known Member
Correct. As far as I know, there is no aftermarket head available for the slant six, Although, at one time or another, some have been made, in very limited quantities, for a very specific purpose.
Charlie, have you talked to Frank lately? Has anybody for that matter? I sure do miss him around here.
I talked to Frank about two or three months ago because I was curious, myself.
He answered his cell phone an seemed glad to hear from me, but was kind of un-specific about why he hadn't been posting much, saying that family goings-on had kept him so busy he hadn't had much time for automotive pursuits, lately. He helped Freddie and myself a LOT when we were in the parts-acquisition phase of out so-called "build," and hooked us up with Charrlie and some others, without whom, we probably would never have gotten as far as we have.
I think he's okay, just has no time for slants, right now.
cjh
Well-Known Member
Once apon a time there were heads done by Yella Terra....they were OEM heads that had been crack tested, checked, modified, ported and flowed on a bench.
They haven't done them since the mid 80's, me thinks.
Charrlie_S
Well-Known Member
If you want a reworked stock factory casting, you can have Mike Jefferies do one for you. He will do anywhere from mild to wild. You need to tell him what the head will be used for.Ok Ill take one of these, sounds like its what Im after
Where do I sign up
I talked to Frank about the end of October, he is happy and enjoying family, I called him just in case I needed to sell my big valve shaved head he built for me and said yes he would by it, but I made everything happen with out selling it.
I miss seeing him here as well, I enjoyed a few visits to his house and new shop, he had a slant on the test run indoor engine room at the time.
Charrlie_S
Well-Known Member
I havn't in a while. I guess it is time to give him a shout.
I agree Charrlie :coffee2: I may give him a call about 1 pm eastern time, I bet he will be happy to hear from you and I on the same day :coffee2:
Thanks for that, someone may have already given me his contact info as well but just in case and if you have it will you P.M or e-mail me that info.
DartDude335
Well-Known Member
you know I have seen alot of talk about this engine but no proof that its a hoax ..Just alot of people saying it is!
I could talk to Radar from R&J Performance . He carves Hemi heads out of billet quite often. They scratch built a billet head for a John Deere pulling tractor. lol It would cost thousands and then the intake to make it work. Headers not quite so hard to fab.
Mike,
You bring up a good point; cost/effectiveness.
I have spent a lot of time trying to learn what I could about this engine from this and the .org message board, several books, including the three-volume set of the history of the making of the slant six by its designer, Willem Weertman (no typo) and all the evidence tells me one thing:
This engine was designed to be a small-displacement (170 c.i.d.) engine, with small bores. The cylinder head was a product of that line of thinking and the modification of the original design, to include a bigger displacement by stroking it a full inch, was obviously never a part of the original plan.
The fact that the cylinder head was not touched in the original enlargement was evidence that it was a band-aid approach to a bigger problem. It had no chance to breathe effectively through the same ports and valves that had worked so well for 170 cubic inches, with now, a 33-percent increase in displacement; It became a low-rpm workhorse, lugging station wagons around, and that it worked as well as it did in the 198hp Hyper-Pak 225 Lancer motor was a minor miracle.
The fact is, the small cylinder bores (and the resultant narrow combustion chambers, dictating small valves,) coupled with the rpm-limiting long stroke (talking about the 225, here) become a one-two punch that make the process of attempting to get a LOT of power out of that engine an exercise in frustration. You can spend money on high-compression pistons, radical camshafts, exotic induction systems, high-rpm ignition systems, electronic fuel injection and expensive ported and polished cylinder heads with thee biggest valves you can fir in them, and still end up with a motor that has a thoroughly un-impressive output... BECAUSE the head cannot be made to flow enough air to support the kind of air movement necessary to generate sufficient volumetric efficiency to do the job.
It might be possible to move the kind of air you'd have to have to make 400 horsepower, naturally-aspirated, with a 4-valve head (but, given the small bores, it would take a designer who knew exactly what he was doing... and it MAY even be possible to get a 400 h.p. slant six, naturally-aspirated, using a 2-valve, hemi configuration head, to gain enough valve-size increase, and the superior breathing of a cross-flow design, but at what expense?
The 400 h.p. slant six is achievable with the addition of such power-adders as nitrous oxide, supercharging and turbocharging because it was built, originally, as an aluminum engine... which, for whatever reasons, didn't pan out. When they changed the engine over to all cast iron, the cheapest thing to do was make VERY FEW CHANGES if thee design structures of the engine, so it was built with extra-thick main bearing saddles, a forged steel crank, thick top deck specifications, and an 84-pound cylinder head... with the result that this motor is especially suited for levels of boost that would make scrap metal out of most of the V8s Chrysler builds.
Both Tom Wolfe and Ryan Patterson (both, FABO members) have exceeded 25 pounds of boost with their slant sixes with no apparent harm to thee engines. Drag strip performances have shown that those engines each make approximately 500 horsepower...
It would seem, given all of the above, that is you want to make horsepower out of your slant six, the smart money is on a hair dryer... It's in the motor's DNA... installed at its inception when the small bores were mandated by the front office.
Mark Ethridge (GuzziMark on FABO) has gone impressively fast with an un-blown, all-motor early Valiant, and holds several records to prove it.
He did it through ingenuity, hard work and persistence. He was able to go that quick, partially, by putting his car on a serious diet; It only weighed about 2,350-pounds for some of his record-setting runs. Not by making 500+ horsepower...
Most A-Bodies weigh about 3,200 pounds, give-or-take, plus driver, so getting one into the thirteens without some serious weight-reduction, is a tall order...
That takes about 300 HP, which is somewhat difficult for a stock-weight A-Body, naturally-aspirated. Not so hard, with a hairdryer...
I know sone of you aare getting tired of me posting this amazing video, but it proves my point so well, forgive me, one more time!
[ame="http://www.youtube.com/watch?v=7QzUfV8iTpQ"]Turbo Slant Six 10.74 @ 127 mph 7-19-10 - YouTube[/ame]
All of the above is nothing more than my opinion... I am obviously no expert.
Thanks for listening!!! :cheers:
67 Power Wagon
Hemi Pawr or BUST!
That's a \6 with a turbo on it? DAMN it walks all over the GM beside it and it doesn't even have a chance! Pretty awesome, none the less!
Charrlie_S
Well-Known Member
I agree with Bill. The most cost effective way to make big HP numbers with a slant is a turbo. To get the same numbers normally aspired, would make the engine unstreetable. I did a real simple turbo slant back in the late '70's by putting a Corvair turbo on a 170 65 Valiant. I could drive it to the track, open the exhaust, put on the slicks, and go 13.4's at 104 mph. About 10 lbs boost.The hardest part was the "tuning". Back then there was very little turbo info available to the "hot rodder", no boost timing master, no air fuel ratio gauges. All I had was a EGT from a airplane. My water/alcohol injection, was a windshield washer setup, with the nozzles spraying down the carb. Triggered by a 5 lb pressure switch.
Thanks for the support, Charrlie! It means a lot, coming from someone as knowledegable and as experienced as you.
Of course, there are some who for one reason or another, shy away from a forced induction motor (and, there are several good reasons to do that,) but everyone need to know thew facts, so they can make an informed choice.
Turbocharging is not simple, if done right, and has a pretty steep learning curve, but is gaining popularity all the time, so there is more and more help available to get the job done. It's not like it was when you started your turbo project years ago, and you had to figure everything out as you went, without any info or advice.
We are about to get our car to the strip for the first time... and I figure if we (two 75-year-old geezers) can do it, anybody can do it
Photos of our junk, below...
Thanks again! =P~
You got my support too, Bill. I've always agreed with you that it's the most cost effective way. I just get tired of READIN about it everywhere. LMAO
You know I'm messin with you.
You know I'm messin with you.
-
