Super Charged Slant Six

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67 prostreet gt said:
why use a slant six with force induction when i can beat you with a small block v8 for a lot less time and a heck of a lot less money?
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Because, while effective, that route requires no intelligence, experience or creativity.

Not everyone is all about going as fast as you can for the least amount of money. Folks either get that, or don't. I haven't the slightest interest in seeing another V8 A-body at a car show, no matter how nicely it's built. Same goes for V8 Challengers, Camaros and Mustangs. Once you've seen a few dozen, you've seen 'em all.

I'd stop and admire this car for hours. To each his own.
 
67 prostreet gt said:
why use a slant six with force induction when i can beat you with a small block v8 for a lot less time and a heck of a lot less money?
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I have been around drag racing for longer than I care to admit. It was a revelation to me when I realized, finally, how fast you could go with slant six/turbo setup for very little money. Tom Wolfe's BONE STOCK shortblock /6 (had a 4bb carb a Buick turbo and a Buick turbo welded to a stock /6 exhaust manifold, went 12.95 in a 3300-pound DART at 102 mph...

He spent VERY little money doing this, though I dunno how much.

A stock 340 at that weight won't run anywhere near that e.t. I have a '72 Valiant with a 360 Magnum engine (also stock) which I had a mild roller cam in, with a 4bbl and dual exhaust (early 340 exhaust manifolds) and the best I could get out of it on 8" drag radials at sea level was 13.35 @ 102. And, it was geared 3.90.

He (Tom) has changed a few things ($$$) like added forged pistons and rods, and a cam. Big valves and ported the head. Built headers.

Now, it goes 11.0's @ 122 into a 15 mph headwind, with a 2.76 gear.

We could argue forever abut this, but until you closely analyze the costs of building a turbo /6 and a small block that will equal its performance, you really don't know that the V8 is cheaper.

I don't believe it is.

There is a lot to consider; the basic engine cost (they give away slant sixes,) The final drive ratio (slant 6's LOVE ratios in the 2's on the drag strip,) while that V8 needs something above 4.56:1 to really get the job done in the quarter, which ruins it as a highway car, and the slant six is about 100 pounds lighter. (and, costs more)

The /6 can make 500+ horsepower at 5500 rpm, while the 340/360 needs to wind up like an 8-day clock to really put out.... engine life.

Ryan Peterson's turbocharged 2700-pound /'66 Valiant, /6 car runs 127 mph in the quarter with a 727 transmission! Might go 130 with 904, who knows??

He might tell us how much he has in it to get it to go that fast, but I'll bet you can't build a small block V8 for that amount of money.

A 127 mph Duster with a small block is a chunk 'o change....

Just my 2-cents...
 
I LOVE raceing guys like 67 prostreat gt,with his V8.They HATE getting beat by a all motor slant six car.Guzzi Mark
 
madmax/6 said:
I LOVE raceing guys like 67 prostreat gt,with his V8.They HATE getting beat by a all motor slant six car.Guzzi Mark
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And you don't feel the slightest bit guilty either !!!! I went up against a kid from my daughters High School at our local 1/8 mi track,and that kid was sooooo PO'd that he had been beaten by a /6 that it made my $$$ spent worth every penny !!!:wav:
 
Bill Dedman said:
My opinion (though nobody asked... lol) is that, if through some esoteric arrangement of parts in the reciprocating assembly, you could, somehow, build a 325 cubic slant 6 motor with a decent (1:1) bore stroke ratio, unless a free-flowing cylinder head (300 cfm, intake; 240 cfm, exhaust) can be fitted to this "wunderblock," it's never going to perform very well.

Horsepower is all about moving air... in this case. lots of it. I don't see ever getting it done, normally-aspirated, with a cylinder head that was designed to feed 170 cubic inches...

Just my 2-cents.:pain10:
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the bore/stroke issue is the easy part... chevy 305 pistons and an offset ground 198 crank... ooppss! i need to keep my mouth shut...

and the problem your having is that your looking at the head as cast... when i look at it i see some ports that dont belong in a 6 head!
 
and the problem your having is that your looking at the head as cast... when i look at it i see some ports that dont belong in a 6 head!

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Doesn't matter how big you make the ports; they all end at valves that are too small to effectively feed much more than 200 cubic inches, if that.

The factory killed all chances of a large displacement /6 ever breathing very well, normally aspirated, when they chose a 4" bore center spacing, which dictates really small-diameter valves, regardless of the port sizes.

The stock cylinder displacement (which ALREADY has a stroke that's pretty much at the max for work above 7,000 rpm, due to egregious piston speed,) is about 39 cubic inches per cylinder, which purely by chance, happens to be almost exactly the displacement of a 302" small block Chevy V8 (Z-28 variety.) If you'd been paying attention, back in 1967, when that engine first saw the light of day, you'd have been aware that it was a particularly well-breathing engine, with several good things about its design that gave it an edge. It had a 4" bore, and a 3" stroke, giving it room for 2.02" intake valves and 1.6" exhaust valves.

The slant 6, which is trying to feed (in stock form) almost the same displacement per cylinder, when we fit it with OVERSIZE valves (as large as most guys can get into the combustion chamber) that are 1.74" on the intake, and 1.5" exhaust.

The stock Chevy intake (2.02") is 15 percent larger in diameter than the maxed-out /6 valve, while the 1.6" stock Chevy exhaust valve is 6-percent bigger-diameter than the Mopar, that is the "oversize" unit.

I am sure that there are some one-off Mopar /6 heads out there that have larger valves that these, due to offset guides, but the combustion chamber wall's proximity will probably shroud the edge of the valve to the extent that the gains in overall size may well be cancelled out by the difficulty in getting air to flow around the periphery of the valve, due to the closeness, with the increased size.

In short, getting sufficient air flow in and out of a large displacement /6 (300 cid?) would require changing the bore/stroke ratio to something more amenable to large-diameter valves, and/or shortening the stroke to something more in the area of a 170, so that it could wind like that Chevy, and if you do that, there goes your displacement.

It's a physics problem that seems (to me, anyway) not to have an answer, beyond forced induction.

The good part is, because of their incredibly strong infrastructure (due to their origin as an aluminum engine,) that (forced induction) makes all kinds of sense on this engine.

My 2-cents..
 
StrokerScamp said:
Yall can talk about me in the first person like I'm here, cause I am. I stand by what I said. Any engine, regardless of what type build will benefit from cool air that is directed from out of the engine bay. I'm no forced induction expert, but have built a few roots blown engines in the distant past. I do know they also benefit greatly from an intercooler, regardless of how the build was done. I wasn't meaning to knock the build. It's great. I'm jealous....I wish it was mine. But if it was, the inlet side of that blower would be substantially different. Ok. Yall can talk about me again.
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I stand by my statement about your comment. the attitude of hating on someones car with the terms...BULLSHIT and STUPID usually come from someone who does not have a ride nearly as nice or as fast as the car they are picking apart. read hemidup's info on the build...It was not needed to have a intercooler or cold air inlet because of the way it was built. Sharadon tested it both ways with no substantial gains and the owner did not want a big hole cut into his car or a big oversized hood scoop. This car was BUILT! Not SLAPPED together!
 
67 prostreet gt said:
why use a slant six with force induction when i can beat you with a small block v8 for a lot less time and a heck of a lot less money?
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if we have to explain, you will never understand. you order your parts out of a catalog, where as i make mine. but a little fabrication and being different doesnt scare me.
 

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well ive been around mopars almost my entire life and the slant six as i used to see it, it was a hunk of iron for grandmas then i was introduced to the 2jz toyota and they really opened my eyes about 6 cylinders, but i had my reserves about the chrysler slant six, other than the fact that you just cant kill them, but now that i see how fast you guys are going i may go in a different direction with my 67 dart, it with a all iron 440 truck motor weights 2400 pounds, so im deliberating either a 2jz toyota , a 500 ci v8 with turbos or maybe a slant six, what do you guys think? its got to be pump gas ready, drieable for every day, and still be able to kisk the living snot out of almost everything in its way, any inout would be helpful
 
Shaker223 said:
A+ :downtown:
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Frank and Tom,

Thanks for the kind words, but I totally missed something that is very important, because I am really ignorant about mathematical relationships as regards diameter versus area. I failed second year Algebra TWICE, if that gives you any idea of my shortcomings....

Here's the deal: Some of you may have already figured this out...

Though the DIAMETER of the 2.02" Chevy valve in the Z-28 head is only (as reported) 15 percent larger that the /6's oversized 1.75" valve, if you do the math and calculate for valve AREA (instead of simply the diameter,) the fact is, the Chevy 2.02" valve AREA is THIRTY THREE PERCENT LARGER than the area of the 1.75" /6 valve.

Like I said, BOTH engines have 39 cubic inches per cylinder...

Such are the wages of the small bore /6 design, and resultant small valves, even taken to the max (without going to "heroic measures.")

I missed that completely, so there goes my A+.... just like in school...:cwm10: Who am I kidding; with a performance like that, I'd be lucky to get a "D"....

If you're interested, the difference in the area of the 1.5" (oversized /6 exhaust valve,) and the STOCK Chevy Z-28 1.6" valve is 14 percent.

I apologize for the confusion...:banghead:

I only point this out to try to illustrate how REALLY small the /6 valves are in relation to another engine wwhich has reasonably-sized valves due to the large-bore valve size capability.

I think that forced induction can make an end-run around this problem, and Ryan Peterson's car, along with Tom Wolfe's equally powerful turbo'd /6 are proof of that.

Thanks for listening!
 
67 prostreet gt said:
well ive been around mopars almost my entire life and the slant six as i used to see it, it was a hunk of iron for grandmas then i was introduced to the 2jz toyota and they really opened my eyes about 6 cylinders, but i had my reserves about the chrysler slant six, other than the fact that you just cant kill them, but now that i see how fast you guys are going i may go in a different direction with my 67 dart, it with a all iron 440 truck motor weights 2400 pounds, so im deliberating either a 2jz toyota , a 500 ci v8 with turbos or maybe a slant six, what do you guys think? its got to be pump gas ready, drieable for every day, and still be able to kisk the living snot out of almost everything in its way, any inout would be helpful
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Even though the turbo's /6 is a killer motor for its size, it has its limitations, when pitted against an engine twice its size, also turbocharged.

A 500 cid turbocharged engine in a 2,400 pound car would, in my estimation, be borderline un-driveable on the street. Just right...:angryfir:

The /6 would probably run 11 flat on pump gas, be dead reliable and cheap to build, comparatively... plus, how many egos do you want to crush ("You got outrun by a SIX????")

You pays your money and you takes your choice.... LOL!
 
thanks, ive got the block and the turbos for the 500- ci, and ive got a tranny and rear end built to handle well over 1200 horse so i may go with the 500 with twins after all, though i do still like to think of the idea of the 2jz in there though
 
67 prostreet gt said:
thanks, ive got the block and the turbos for the 500- ci, and ive got a tranny and rear end built to handle well over 1200 horse so i may go with the 500 with twins after all, though i do still like to think of the idea of the 2jz in there though
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That will be awesome.... just awesome!!!:toothy7:
 
Bill Dedman said:
and the problem your having is that your looking at the head as cast... when i look at it i see some ports that dont belong in a 6 head!

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Doesn't matter how big you make the ports; they all end at valves that are too small to effectively feed much more than 200 cubic inches, if that.

The factory killed all chances of a large displacement /6 ever breathing very well, normally aspirated, when they chose a 4" bore center spacing, which dictates really small-diameter valves, regardless of the port sizes.

The stock cylinder displacement (which ALREADY has a stroke that's pretty much at the max for work above 7,000 rpm, due to egregious piston speed,) is about 39 cubic inches per cylinder, which purely by chance, happens to be almost exactly the displacement of a 302" small block Chevy V8 (Z-28 variety.) If you'd been paying attention, back in 1967, when that engine first saw the light of day, you'd have been aware that it was a particularly well-breathing engine, with several good things about its design that gave it an edge. It had a 4" bore, and a 3" stroke, giving it room for 2.02" intake valves and 1.6" exhaust valves.

The slant 6, which is trying to feed (in stock form) almost the same displacement per cylinder, when we fit it with OVERSIZE valves (as large as most guys can get into the combustion chamber) that are 1.74" on the intake, and 1.5" exhaust.

The stock Chevy intake (2.02") is 15 percent larger in diameter than the maxed-out /6 valve, while the 1.6" stock Chevy exhaust valve is 6-percent bigger-diameter than the Mopar, that is the "oversize" unit.

I am sure that there are some one-off Mopar /6 heads out there that have larger valves that these, due to offset guides, but the combustion chamber wall's proximity will probably shroud the edge of the valve to the extent that the gains in overall size may well be cancelled out by the difficulty in getting air to flow around the periphery of the valve, due to the closeness, with the increased size.

In short, getting sufficient air flow in and out of a large displacement /6 (300 cid?) would require changing the bore/stroke ratio to something more amenable to large-diameter valves, and/or shortening the stroke to something more in the area of a 170, so that it could wind like that Chevy, and if you do that, there goes your displacement.

It's a physics problem that seems (to me, anyway) not to have an answer, beyond forced induction.

The good part is, because of their incredibly strong infrastructure (due to their origin as an aluminum engine,) that (forced induction) makes all kinds of sense on this engine.

My 2-cents..
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FYI Bill, we stuck 1.81" int/1.55" exh valves in the heads. Had to unshroud the copper head gasket and cylinder walls for the intake valve.
 
hemidup said:
FYI Bill, we stuck 1.81" int/1.55" exh valves in the heads. Had to unshroud the copper head gasket and cylinder walls for the intake valve.
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see thats near what valves i was looking to run... maybe even a slightly smaller exhaust valve and bigger intake...

and for bill... thanks for giving me a reference as you shown above...

this helps alot in placing goals for what i can make happen...

my next question would be do you need a 2.02 intake valve to flow 300cfm??
 
moparsofmn said:
I stand by my statement about your comment. the attitude of hating on someones car with the terms...BULLSHIT and STUPID usually come from someone who does not have a ride nearly as nice or as fast as the car they are picking apart. read hemidup's info on the build...It was not needed to have a intercooler or cold air inlet because of the way it was built. Sharadon tested it both ways with no substantial gains and the owner did not want a big hole cut into his car or a big oversized hood scoop. This car was BUILT! Not SLAPPED together!
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Dude, you're gettin way to defensive. Take off the girlie pants so you won't get your feelins hurt so much. I never hated on anything. You're the only one hatin...and sounds like you got lots of it.
 
slantscamp said:
if we have to explain, you will never understand. you order your parts out of a catalog, where as i make mine. but a little fabrication and being different doesnt scare me.
Click to expand...

That's gonna be nice. Excited to see your progress.
 
I just want anyone to get close,To my simple stupid build with a Jefferiers head and cam recomend,and my novice build.I still feel I got lucky on my build.I think smarter,more experieced builders should bee quicker than me and have more Hp.My next motor is the one that will really raise eyebrows.Will bee the same with more compression.Hopefully a 10th quicker.
 
hemidup said:
FYI Bill, we stuck 1.81" int/1.55" exh valves in the heads. Had to unshroud the copper head gasket and cylinder walls for the intake valve.
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That's now only 25% smaller (in area) than the 302 Chevy we've been talking about, on the intake, and 6.5% smaller area, on the exhaust.

The exhaust isn't that much of a problem, but 25% (intake) is a huge deficit.

Still, those are great numbers for a slant six!!!

Did you have a chance to flow the head with the bigger valves???

I don't know the flow numbers for the Chevy head... could be anything.



I was just trying to point out the built-in difficulty in getting high specific output numbers from an engine that has the deck stacked against it by the factory, but, I don't think I have to shore up that argument with any more statistics.

Just so you don't get any erroneous ideas, I would rather PUSH a Mopar than drive a Chevy.... and, that's the truth!

It is astounding to me, that Mark's engine runs as well as it does, in view of his uphill battle as regards airflow. He and Mike Jeffries must have made a deal with the Devil!!! That thing flies.... :happy7:
 
madmax/6 said:
I just want anyone to get close,To my simple stupid build with a Jefferiers head and cam recomend,and my novice build.I still feel I got lucky on my build.I think smarter,more experieced builders should bee quicker than me and have more Hp.My next motor is the one that will really raise eyebrows.Will bee the same with more compression.Hopefully a 10th quicker.
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Mark,

I don't think that's gonna happen (anyone making more HP/CI than you,) and yes, I think you got lucky, but I also think you make your own luck.

I was wondering if you have any hard numbers regarding that Hurricane intake as regards a comparison to a different 4-bbl manifold. Just curious... We are going to run the long runner version on our turbo motor, but will likely try the short-runner version, later on.

Thanks for any information!
 
madmax/6 said:
I just want anyone to get close,To my simple stupid build with a Jefferiers head and cam recomend,and my novice build.I still feel I got lucky on my build.I think smarter,more experieced builders should bee quicker than me and have more Hp.My next motor is the one that will really raise eyebrows.Will bee the same with more compression.Hopefully a 10th quicker.
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i think you should shoot for 15:1 on 118 race gas...

basically 15hp from every point of comp...
 
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