How many people saw the Hot Rod article on Chevy's new in line six? That engine proves what we have been saying for years, that an in-line six can be made to perform. Gobs of horsepower(I think around 270), torque, and red lined at about 6'300RPM. The secret is in the head. Four valves per cylindar, and over head cams. Of course the cool MPI and nifty exhaust manifold don;t hurt. I have said for years, if the slant had a good head, it would REALLY wake up. This Chevy engine produces over 1 HP per cubic inch. Not bad.

That engine does have some sweet design features. If I had all that stuff (which I may eventually), I think my engine would get at least 1.5 HP/in. Right now, my '64's engine makes more per inch than that engine, and almost as much total (mine is 250-260HP). However, I would bet the torque/HP curves are broader than mine and the emissions are lower.

Lou

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Home of Slant6-powered fun machines since 1988

Don't you think your engine would be stronger with a four valve head? I still can't figure why yours is so strong, given the basic build up it has. How do you account for it's strength?

Does anyone here think a four valve head for a slant is entirely, insanely out of the question? I don't have any ideas about how hard it would be to design and produce. We now have after market manifolds, and supension parts. Back in the 40's guys were making exotic heads for Ford flat heads v-8s. I guess the volumn was enough to make it practical. The most common similar production heads would be found on the Nissan z cars, the Toyota Supra engine from the 80's and the BMW slant. Anybody looked at those for similarities in bore, and spacing. I know this is complicated. Just dreaming, and trying to stir up a discussion.

I'd be happy with a stock 2 valve replacement with a nice quench shelf in the open area of the chamber (like the 1989-1991 LA block '302' head had). That way I can take advantage of higher compression ratios.

4 Valves would be neat, but some flow tests, and combustion chamber thought and shape has to be tested and thought up, revised, computer modeled...

someone needs to win the PowerBall first....

-D.Idiot

I have a Nissan Skyline with a lovely two valve hemispeherical head design.(inline six) Lovely big round ports, nice big valves and a beautiful wide torque curve. Of course it's fully computer controlled. Only thing I hate about it is a slight lack of bottom end torque, but it's only a 3 litre engine. This thing when stock would rev to 5800 rpm, but pull hard all the way there. If you could find an aluminium cylinder head with the correct bore spacings, I am sure you could cobble up some sort of way to bolt one down and run a timing belt on the front of the engine. If anyone wants some quick measurements or photos, I have a spare head on the workbench. These heads are $200 Aus second hand here.
We have an inline six engine Ford(sorry for the four letter word!) Australia produces over here that would make you guys wet your pants! 4 litres, overhead stuff, very advanced engine management, variable intake runners etc, and theres a turbo version which is more powerful than the quad cam modular V8 they put in the same car.
A quick search for Ford Australia should get you there.

Regards, Andrew.

I would be interested in a 4 valve head if such a thing were feasible (say less than $3k). For now, the stock head has made well over 300HP NA in several cars.

Vader, I think my engine is just a good combo - high compression (11:1), bigger valves, slightly loose tolerances on bottom end, medium/big cam, and very well tuned . I can wring another 20-50 HP out of this sucker before I go to forced induction or exotic heads. The car will see 13s or better next year...

Many of the other make heads have been investigated by Slant racers - BMW, Supra are somewhat close and have been researched, but would be too much work.

Typhoon, sounds like very fun stuff down there. I hope to get down to see Oz sometime in the next year or so. Engine management, at least for spark and fuel, is within anyone's reach right now.

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Home of Slant6-powered fun machines since 1988

The valve layout would be interesting on this four valve head. I assume you'd still have the 2 intakes on one side feeding from one runner of a manifold and 2 exhausts on the other side feeding a single exhaust runner what kind of flow would the second valve get once the first is open? just curious of the logistics?

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It is easier to REACT,
than it is to THINK!

Middy.

Dart270,

If you are coming to Australia, you should hire a Falcon for the day. Very nice cars to drive. Lots of grunt.
In Australia, we have always favoured larger six cylinder engines for our sedans. Our fuel isn't as cheap as it is over there, and with the large distances we cover, they just make more sense than a V8. We even got the Chrysler "D" engine, which was developed in the US as a replacement for the Slant, but was never produced over there. It is a fairly compact design, with a canted valve cylinder head, not unlike an LA type head, but with nice square ports.
We got the design, and tweaked it a little...a stock 265 made 203hp and 262ft lbs of torque, while the hotted up six Pack engine with webers made 270hp and 318 ft lbs torque at 5000rpm. Those figures compare quite well to a small V8, and are considered fairly conservative.

Regards, Andrew.

Just go down to your local machine shop and ask to look at a BMW slant six head, (he might not know it is a slant ). And you will see that the four valves nearly fill the roof of the chamber. I assume both intakes open together,and both exhaust open together, although I know some hondas have trick valve timing that might not be that stright forward.
Typhoon. The Australian cars always made me jealous of you guys. Even the "new" GTO is a warmed over Aussie car, is it not?

Yes, the new GTO is a Aussie car. I think GM is working on bringing a few other Holden? cars over in the next few years, also.

Just to cover all of our bases here, Mercedes (should I say DaimlerChrysler?) had built a pretty mean 3.6 liter inline 6 and dropped it into thier 95-98 C Class cars as an AMG model. I have a 99 AMG with a 4.3v8 and that thing rips, but these inline 6's are pretty potent also.
One thing though, it's not slanted at all! Specs below:

Engine DOHC 24-valve Inline 6-cylinder.
Compression ratio 10.5:1
Displacement 220 cu in/3,606 cc
Net power 276 hp/206 kw @ 5,750 rpm
Net torque 284 lb-ft/385 N.m @ 4,000 rpm
Fuel and ignition system ME 2.1 fully electronic fuel injection and ignition with antiknock control.
Fuel requirement Premium unleaded gasoline, 91 pump octane.
Transmission Driver-adaptive electronically controlled 5-speed automatic.
Rear axle ratio 3.07:1
Bore x Stroke 3.58x3.64 in/91.0x92.4 mm
Maximum engine speed 6,400 rpm
Alternator output 14V/90 A
Battery rating 12V/100 Ah
Transmission Driver-adaptive electronically controlled 5-speed automatic.
Fuel capacity 16.4-2.1 tank-reserve/62.0-8.0 gal/l
Oil capacity 7.4 qt/7.0 l
Coolant capacity 10.6 qt/10.0 l

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72 Scamp 225 /6, auto, radio delete, alum super six, cold air duct, pertronix ignitor II and flame thrower, 3.23 rear, 2.25" free flow exhaust

Is your new GTO a 2 door sort of thing with a sweeping roofline at the back..fairly large car? I believe they are Holden Monaros. GM over here has been exporting a lot of Commodores(under a different badge) to the US, UK and Middle east. A mate has a company car, it's a Commodore "Lumina" which I know is a US model, so I assume it is that car or a derivative. I also have noted that our locally built cars have a styrofoam filler plug in the floorpan where it meets the firewall on the passenger's side, which is where the pedals would swing to in a left hand drive car.
Interestingly, GM uses US engines in it;s cars here, we still have the old Buick 3.8 V6 noisily churning away in cars, and the 5.7 litre Chev is the performance engine.
To bring it back on topic a bit, Chrysler used to bring in all it's V8 engines(and slants) as fully assembled crate engines, complete with alternators etc, but the D engine I mentioned earlier was completely locally built.
If anyone is interested, I have factory workshop manuals with cutaways of the D engine, photos of major subassemblies etc. Just have to get them to a scanner and scan them.
I am actually considering swaping the slant in my truck for a D engine as it's very hard to get a performance manifold for a slant here.
You may be jealous of our cars, but it sure works the other way as well...we NEVER had a 426 in anything over here!

Regards, Andrew.

A decent head to copy for the slant six might be the Mopar 2.4. The bore center spacing is 5mm closer, the 2.4 bores are actually slightly larger than a slant six. The 2.4 pistons have domes, these might work in the 225 with that type of head. The deck height on the 2.4 is lower than the 170. The turbo 2.4 head is the same as the normally aspirated version. The base non-turbo 2.4 has 150 hp, a 3.7 liter version would be about 230 hp, and would be smooth and quiet with a mild camshaft profile, swap the cams to make more than 300 hp. I wouldn't mind seeing a Mopar five or six based on the 2.4.

A five based on the 5.7 hemi design would be 22" long plus a little more for the front cover and bh flange.