cleaning up the slant six head
Thanks Bill, all good info and interesting stuff. That is a possibility for the future of this engine just cause of the neat factor.
Not sure if you are aware though that my 225 is cradled in between the legs of a 6000 pound 4 wheel drive truck. My build is not for performance in that I would like to see it go fast, my build is for reliability/efficiency, I would like to make the engine operate as efficiently as is possible, its just a toy, something I have been playing with.
I do as mentioned like the idea of turbo, I would prob. be the only guy with that set-up in a vehicle such as mine and so I will keep all these facts in mind.
Just to throw it out there from what I have been reading on this site and slant org site installing larger valves in my head would be a complete waste of time/money but that confuses me cause I know the faster I can get air/fuel into the chamber and then get it out the better or more efficiently the engine will run so why not up-grade the valve size seeing how there is room for a larger valve?
Is it because the chambers leading up into the valves within the head just wont support or wont accommodate the extra fuel/air flow?
Yeah the DZ engine ran 2.02s but that was a performance engine from the get-go whilst the standard 327/350 ect were runnin 1.94 for many years on their 4 barrel cars/trucks and still kickin ***.
So if the cylinder jug diam on /6 is essentially same diam as the 302 than whats the drawback with the head to jug match?
I am confused but trying to understand better so that I can come up with my own conclusion that the / head on the 225 is a futile endeavor.
1930,
Thanks ffor the kind words; you're a patient man...
To begin with, I am going to say right off that I don't really understand the usage that you intend for this truck. You haven't said whether it's a daily-driver, workhorse, or what. You did say that it was going to be just a "toy," and that high performance was not a factor, in that it weighs 6,000-pounds.
My experience with cars and trucks is very limited. I have a handicap when it comes to talking about subjects like this, because I literally grew up (a long, long time ago,) on drag racing and that really skews my thinking.
The mere thoughts of using a 5,000-pound truck as any kind of a "toy" sets my so-called mind to thinking, "WHAT? 6,000 POUNDS??? PUT a CUMMINS TURBO DIESEL IN IT!!!"
I would contend that this environment is NOT a good place for a turbocharged slant six, and even with all the accolades I spewed forth last night, and as much as I admire and respect that engine, I don't think either IT or YOU would be very happy with such a collaberation.
So, forget I said anything. I run off at the mouth, (keyboard?) half-cocked at the slightest provocation and should not have entered this discussion because (as usual,) I didn't have all the facts.
One thing, though; the comment: " Yeah the DZ engine ran 2.02s but that was a performance engine from the get-go whilst the standard 327/350 ect were runnin 1.94 for many years on their 4 barrel cars/trucks and still kickin ***.
So if the cylinder jug diam on /6 is essentially same diam as the 302 than whats the drawback with the head to jug match? "
But, the
CYLINDER DISPLACEMENT is the same on the 302 Chevy and the 225 slant six, (39 cubic inches,) the valve size is smaller on the six by an egregious amount (2.20" vs 1.75" intakes And 1.50" vs. 1.6" (Chevy) exhaust, and that is comparing stock Chevy valves to oversize MOPAR valves.
The reason for this difference in size has everything to do with bore-center spacing.
The Chevy V8 is built with 4.4"bore center spacing, vs. 4" for the slant. That's nearly half an inch difference, giving the G.M. car way more room for bigger valves.
The Chevy has a 4"-bore, while the slant six only has a 3.4", stock.
They have identical cylinder displacements because the Mopar has a 4.125" stroke, while the Chevy's stroke is just 3."
You can see the problem when it comes to moving air through this inline engine. It all goes back to the factory decree that the new (1960) Valiant was mandated to be designed with a short , low, hood, That dictated a short, low, engine. They had no choice but to engineer the block with small bores to keep the overall length as short as possible (and to lean it over at 30-degrees to keep it as low as possible.) They even took more advantage by placing the water pump alongside the engine, to help minimize length from the fan-to-the-firewall.
To exacerbate the problem, it was originally designed as a 170 cubic inch motor, and the head was designed with those parameters in mind.
The next year, when they needed some economical B-body station wagon engines, they found that the 170-inch version just didn't have the grunt to lug around 3,800-pounds comfortably, so they made it 33% bigger by stroking it a full inch. They were not in the mood to try and make it a runner, so they did NOTHING to increase breathing capacity.. so, an asthmatic, strangulated, 225 was born, sporting the same head that was designed for the 170 motor. That never changed on the millions of these engines that were eventually built. There was never been a better-flowimg factory head (except for some hard-to-get pieces that originated in Argentina,) and the aftermarket has never been interested because of the tiny bores... just no room for decent-sized valves.
So, it's no wonder that a 302 Chevy is a barn-burner race engine and a 225 cant even made INTO one, because of its physical limitations.
A naturally-aspirated, well-built 225 has amazing capabilities reliability-wise, but it can never make very much power; think of running a marathon with a piece of duct tape covering your mouth, and the picture becomes a little clearer...
I wish you luck. I feel that there are better engine choices to be made for your truck, but that's just MY opinion.... your mileage may vary.... :blob:
