Mark Ethridge's '62 Valiant holds the records for several Gas Coupe classes (at different weights; same engine) and the Wallace Online cauculator (which, I"ll admit, is just a ball-park figure) pegs his engine at 300 horsepower, or 1.33 hp. per cubic inch (using 2,400 pounds and 115 mph as parameters.) If you know of somebody who has a 225 /6 with higher specific output than this, (on gasoline, normally aspirated) I'd like to be made aware of it. I'm new to this /6 bidness, and have a lot to learn.

The 1.33 is a long way from 1.5, to say the least, of 2.00 hp./cube.

Right now, only forced induction motors (/6's) make that kind of power, to my knowledge.

A new head would help, for sure, but they (N-A advocates) have a long way to go, it seems to me...

My 2-cents...

Well, like I mentioned earlier, there is crossover technology from the Chevy and Ford heads that can be applied to the Slant production head that can get the HP/CID number higher to those willing to do it.

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There's no such thing as too much cam....only not enough engine!

CNC DUDE can you enlighten me on this crossover technology your speaking about or can you point me in the right direction,or where I can find some info I'm getting ready to start another head for a spare
Any info would be much appreciative
Thanks Aaron

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http://youtu.be/2Y4i4UOLiSA

http://www.forabodiesonly.com/mopar/sho ... p?t=126611

One little thing you neglect that will not cross over to a Slant is the mega RPM that you have to turn a 302 Chevy or Boss motor to get them to run. Below 5000 RPM both of them are total pigs. Slants will turn some RPM, but without some big dollar rods and such you will drive over pieces.

You also have to remember that the Z-28 and Boss motors were race bred to start with. The head on a 225 was only designed to feed a 170 inch motor, and didn't really do that too well.

I will agree though that the bore size is the limiting factor for flow and valve size.

Quite honestly, going real fast N/A with a Slant is a losing proposition. Forced induction or spray is the better way to go.

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Official Cookie and Mater Tormentor.

A stock slant head will almost support 1.5 hp per CI on a 170.Clean up casting flash,and do a back cut on the valves and you are right there.

Aaron, pm sent.

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There's no such thing as too much cam....only not enough engine!

Well, Slantzilla, I guess it's all in your perspective: Your comment, "One little thing you neglect that will not cross over to a Slant is the mega RPM that you have to turn a 302 Chevy or Boss motor to get them to run. Below 5000 RPM both of them are total pigs. Slants will turn some RPM, but without some big dollar rods and such you will drive over pieces." is certainally 100-percent true, but I think we need to talk about WHY that's true (about the rpm, and I am certain you already know this.

The Z-28 and Boss 302 motors are "upstairs motors" rpm-wise, because they CAN be. That's where the horsepower is. That being the case, they use valve events provided by cams that take that rpm capability into consideration; the faster you spin an engine, the less time you have for cylinder-filling. BIG valves and ports minimize this problem to some extent, but the slant six, as you have pointed out, offers no such capability. A 170 head on a 225 short block is an asthmatic, strangulated, player, and not much, short of forced induction or N20, can be done about it.

Gains can be made with larger valves and a good port job, with excellent intake manifolding and tuned exhaust headers, but the rpm capability (for a 225... piston speed, you know,) just isn't there.

In the specific output wars, I would put my money on a a 170, up against just about any other 2-valve inline motor with its original head, and be pretty sure I had a good bet, but IMHO, the 225 is a lost cause in that same battle.

That's not to say you can't hop up a normally-aspiraated 225 and have a lot of fun; Look at Mark Etheridge's MAD MAX Valiant... Killer in class racing on the strip. But, I'd bet that he'd go even quicker (in the pounds-per-cubic-inch classes) with the same modifications to a 170 short block, Remeber Pete McNichol's Willys Gasser?

I'm an old guy with not an unlimited amount of time to fool around with this stuff, so I'm taking the coward's way out and going the hairdryer route. That is hard enough... LOL!

Wayne's World is a good example of what a 170 car can do.

From the best times thread we have:

11.436 @ 115.51 mph at A Gas weight, Guzzi Mark 7/16/2011, Samoa Dragstrip

12.98 at 101.03 at Redding, "Wayne's World" 170 cu inch (on gas) 62' Valiant -Wayne Erickson-

Both impressive feats, to be sure!

CJ

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Part of Tyrde-Browne Racing

True, but about the only difference in the long blocks are the CI. Wayne probably has more money in his motor than Mark does too.

They both came from the same engine builder.

Which one do you think will be better? A 170 at 1.5 HP per CI or a 225 at 1.3?

And Bill, 302's are "upstairs" motors because they HAVE to be. Small CI will not make any power at low RPM with tennis ball sized ports. They were road race motors to start with.

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Official Cookie and Mater Tormentor.

Remeber Pete McNichol's Willys Gasser?

We are getting a little of track of this thread but I do remember the willys. Does any one have an info on the car or the man? I know a few years ago he was looking for an intake and he had an early Barracuda. An leads?

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Hyper_pak

Ported 302 Z/28 heads won't flow over 300cfm. They only flow 215 stock. Average ported with 2.02 valves is 250. Radical port work with 2.05+ valves will go 275, radical meaning reduced reliability and very costly.

It's hard to get 300 from a BB Mopar 906/452 head that start with bigger ports and 2.08 valves. Stock flow is around 235. Ported with a 2.14 valve is usually 290-295 is max without reliability issues but 300+ can be reached.

Boss 302 heads flow 270cfm stock, so over 300 is easy to achieve. '70 heads had 2.19 valves, same as an 427 L88 Chevy. '69 heads had 2.23, only .02 less than a 426 Hemi!

Readily available aluminum heads <drool>
200/250 Ford six has them
258/4.0 AMC has them
250 Chevy has or had them
225 Slant Six never had them <sad>

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Slant Cecil

Ain't bench racing fun?

Mark's car is around 300 calculated HP at the wheels, not crank. I was speaking of crank HP so he is around 1.5. Also, 371 HP on dyno with 240 ci in Oz.

Lou

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Home of Slant6-powered fun machines since 1988

There wasn't a SBC head capable of 300 CFM until the late 1980's, and it was an aftermarket one. The Chevy inline 6 production head flows just under 160 CFM in stock trim on the intake, can be upt to 260 CFM with 1.94" valves and bolt-in lumps, and 348 CFM with brazed lumps and professional porting. Creative thinking has raised the bar for the Chevy head considerably, and shows how much farther you can go if you think outside the box.....what can be done to the stock Slant head(put your thinking caps on).

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There's no such thing as too much cam....only not enough engine!

Comparing 3" stroke 4" bore V8s to 3.4" bore 4"+ stroke 6s is just silly.

I race SBC both 3.48 stroke and 3.75 stroke versions and they are completely different even with the same heads.

Talk to me about 4.25" stroke SBC vs a 225 slant ........

no Z28 head flowed 300. I am currently running a set of stock 041 heads on a 350....they are dogs. Not worth the time to port. They were real dogs when I ran them on my 400 block. A set of AFR 195 heads are in my future. Any stroker SBC (3.75 or more) has far more capacity than even the best factory head.

When I put Chev valves in my slant I told the machine shop to treat the head like a chev.....it worked out fine.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Bottom line is that to make use of bigger ports on the same CI you have to turn more RPM.

Howard is fully prepared to do that. Howard likes RPM.

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Official Cookie and Mater Tormentor.