Feature Trends:-Sixes becoming street'n'stripers, not V8's!

xctasy

5K+
VIP
More provocative words about the superiority of sixes. Some of this is from looking at the In-lIners International, Chevy and Slant 6 forums, where, if you do a staticall check, the five following mods sufrface.

After quite a lot of talk form me and others about sixes being the best thing on the street since sliced bread, here is more. I've got to say, I'm biased towards sixes. I'm not anit-V8 or anti-ricer. I am anti-blowing your budget on BS that doesn't work. What follows does work, and is in fact a sum-up of what Jack and others are doing with there rides.

I've been doing some simple parameter calculations on finding the best size of sixes for our cars. There's any thing from 144 to 300 cubes to choose from, which ones are best, and what combos work on a dollar to dollar basis?

Well, I won't be drawn in on which engines are best, all of them are winners. But here's the five steps which are emerging on the in-line six performance front.

Rule 1:Go for the biggest six cylinder engine in the lightest block that will fit, and bore and stoke it within an inch of it's life. If it gets too expensive, go for a bigger block six. If the cost of fitting it is prohibitive, stick with what you have and make it rev more.

Reason? V8's can add up to 5% to vehicle weight, and another 5% to drive train weight through power steering, 9" diffs, bigger auto or manual transmissions. A 25% boost in capacity may result in a 10% weight penalty, and a V8 with its peak torque much higher than where the six has its peak torque. On the street, you won't notice the exta power all the time. You will only see it at the drags after the first 60 feet. Any capacity increase will result in increased thirst, proportional to the percentage in capacity increase. The cost of a v8 block is more than the cost of a six, and if you break it, you can get a six running again in a fraction of the cost of a V8

Rule 2:All else being equal, all six cylinder guys need to know this. As long as you have less than 15 pounds for each cube, the low-end grunt of a six is the equal or superior to those of V8's running less than 10 pounds per cube. In other words, sixes in the 60 ft standing start area piddle all over V8's 50% bigger in the same weight car or v8's the same size but in a 50% lighter car. If the engine is tunned to the same specific out put, like they have the same hp per cubes, the result is even more signifcant.

Reason? A 250, 100 hp net Granada lugging 3750 pounds can real in a 351 200 hp Mustang lugging 3500 pounds in the first 60 feet if the engines are tunned right. There is no substutite for the off line urge of a six-inliner. After that, the v8 shows its extra capacity.

A 200 Mustang lugging 3000 punds will beat or equal a 302 Mustang with 3000 pounds if both are tunned to the same specific out put. Eg a 200 hp 302 will be taken out by a 132 hp 200 in the first 60 feet.

Rule 3: Remember the CEC's. Don't be afraid of any more exotic:-
carb set ups for a six. Even cheap 2-bbls, expensive Triple carb Clifford or Offy set ups are a huge plus. Spending more money on carb upgrades while spending lighter on the rest of the car is fine.
Exhast systems. Sixes are restricted here, and any mod, espeically headers, have proven to be yielders of between 18 to 25% in power, and up to 13% in feul economy for in-line sixes.
Cam technology is now so much better that even poor flowing non-cross-flow heads are able to create huge power increases. Gas flow is always going to be at a higher velocity than a V8, and its almost impossible to screw up a six for road use by over camming.

Rule 4: Gearboxes and Gearing. This is an area Al and Azcoupe are really working on. The modern T5 speed stickshifts are very efficient, and easy to fit. The B10 Jeep 5-speed has been over looked, as has the close ratioToyota five-speeds. All are cheap options if the kits are sorted out. Over drive SROD and Toploader 4-speeds also are hot picks. Geared right, a six will max out the torque to real in v8's and revy ricers in an amazing way.

The C4 auto is one of the best automatics around, even if it lacks the ratio spread. Bolt-on overdrives often require hammer time, and things like gear Vendor set ups may not grow in popularity. Whatever, gearing will be optimised to a very high degree. 4-speed auto conversions, now not considered as a cost effective option, will start to be come cost effective, and my pick is that Turbo 200R's and even Jeep 4.0 Aisin Warner 30/40LE 4-speeds will become the boxes for lazy self shifters amoung us to have.


Notice I haven't even included a Rule 6, drop in an exotic Argentine or Aussie 2V or X-flow heads here. Those using them know there true worth, but I'm certain even the mild American inspired mods on our 144 to 300 sixes are going to be like taking the cap off the champagne bottle for a start. Those wilder heads are like 10th century vino from someones personal stash.

About Rule 4. Talking about autos. There are in Aussie quite a few guys who have bolted on things like AOD four speeds, and blown them up behind V8's. The whole idea is to get a really short 4.11:1 diff ratio, with a huge 67% overdrive. There have been lots of stuff ups, running into $2000. I know, I've been cataloging them. The amount of people who want 4-speed autos out number 5-speed guys, bacause most focus on drag racing or turbo sixes. But there is no knowledge. Only Steve Blechett in Perth, Australia, and the specialists in the US, like Art Carr, have got it mastered, everywhere else there is a trail of broken promises and bank notes. Suerly the area to work on.

Lastly, the best placed here are the early pre 66 Falcons, Mavericks, non 71 to 78 Mustangs and even Aussie Cortina six owners. These have something very special. Very light weight bodied cars, engines that can take heaps of extra power with little or no drive train mods, and that have the space for 250 sixes if the owner wishes. Already people are seeing that the engines are dead reliable and that even modifications that incorporate stock log heads are not futile.

As a dollar per second proposition, there is little to beat a worked in-liner.
 
curse you X, you've made it a certainty, soon as i can get ahold of bubba, he'll be able to buy a 351W...
you make a strong argument
or do i want to keep that for any upcoming truck i buy? to make sure i have a strong engine....
decisions, decisions...
 
I agree X,completly & utterly. As you well know,I own a L-6 from every major U.S. maker,Ford,Chevy,AMC,Mopar. I love 'em all great reliable,little engines,aside from the usual maintenence,they're great engines. I too have always wondered why big name aftermarket company's never REALLY supported the L-6 engine. Seems back in the late 50's through the early '70's you had more aftermarket support from company's like Sper--Co,Mana--frie,Offenhauser,Spark--O--Matic,even Edelbrock. What happened? I have LOTS of these old manifolds,lying around in storage,along with carbs,base plates,ect. Who know's when I'll build a motor? At least I got some of the bits! OO6.
 
Whats quicker from 0-60 mph all other things equal for a 250 six a 4 speed manual with a 2.72 diff or a C4 auto with a 3.50 diff ratio. What would the auto rpm be at about 60 mph?
 
@ 60 mph, 2.92:1 (not 2.72, no such ratio for Borgies) with a set of P185R13's would be about 2470 rpm. That's normally asscoiated with a 3.47:1,2.00:1,1.43:1,1:1 or 3.06:1,1.93:1,1.31:1,1:1 first gear, good enough for :-

3.47:1 @ 4800 rpm, 33.6 mph|3.06:1 @ 4800 rpm, 38.1 mph

2.00:1 @ 4800 rpm, 58.3 mph|1.93:1 @ 4800 rpm, 60.4 mph

1.43:1 @ 4800 RPM, 81.5 mph|1.31:1 @ 4800 rpm, 89.0 mph

The close ratio box with XA-XE 302 Cleveland/250 XE EFI-style gears would be perfect for a 170 hp net streeter in a 2650 pound(unladen) Cortina. I'd say it would yield better 0-60 mph and 1/4 mile times too, an XR6-like 15.2 seconds, 89 mph trap speed. 60 foot times may even be better, who can say?

The auto would do 2960 rpm with no converter slip and 3.5:1's, or about 3100 rpm in most situations.

Gear ratios, can't remember. 2.40:1, 1.47:1, 1:1, something like that.

2.40:1 @ 4800 rpm, 40.5 mph

1.47:1 @ 4800 rpm, 66.2 mph
(89 mph @ 4390 rpm)
1.00:1 @ 4800 RPM, 97.3 mph

Quite simply, it's very slightly too high geared for a perfect 15.2 sec 1/4 mile pass. You should be hauling through the traps just over the peak power level, but quite good for 60 foot and 0-60 mphs. This is a real problem with the otherwise perfect C4. There just isn't the spread of ratios.
 
Cross flow heads flow the best. Not real convinced of that. Most that are offered to us are. I as a designer think mabe not. A cross flow head has the air turning 90 degrees from its entry to get out the exhaust. a "U" flow head its continuig in the same direction to get out. Just something to ponder. The cross flow usally wins only because of comprimises to the porting to get around obstruction head bolts water passages etc. Of course this might be different down under since air and water swirl in the opposite direction :mrgreen: ... just joking
 
Because we are upside down, the oil pump is under the valve cover, driven off the rocker shaft. ;)
 
C-6 and c-4 both are 2.46/1.46/1.00
Unless you have a higher stall converter, manuals seem to be quicker because for one you can rev the engine and slip the clutch keeping it in the power band. (or rev to the moon and dump) An auto with a stock converter must lug from way below power peak. Gearing is certainly a point, but if your building for 1/4 mile, you gear (and converter) accordingly.
Add a tranny brake, and an auto can leave at peak torque or peak hp and bang just like a clutch being dropped.
I prefer manuals, but race an auto because of consistency.(bracket racer)

Brake with 4500 converter= waaaaaPOW! and your nose is in the air! :shock:
 
Ill have to check again but Im sure my owners Cortina manual says the TD 6 200CI came with a 2.91:1 and the 250CI came with a 2.7something.
The one Im running in my TD is out of my 77 TE Ghia would this be a 2.92:1 as I drove it once before pulling it out just to check it and it did 2500 rpm at 80kph. I thought it was a 2.91:1 but maybe not (oh its also got the single rail 4 out of the TE.
In the TD it does about 3000 rpm at 100kph (approx 62 mph).
 
Back
Top