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A Motor Question part II - Gearing

New 3/13/05

Say we have this light Allard replica, a range of opinions exist on the proper engine. Let's approach the problem from another direction.

I think I want a non-peaky motor, one NOT set up for 7500 rpm redline.

If I have enough displacement and TQ, easy to do with a light car I can put in tall enough gears so I red line in first at 50-55 mph like the V8SHO. Because every gear shift costs a car length. With (for example) a 383 chebby I can finish an autocross and never shift.

I don't mind shifting, shift at 25, 50, 80 mph in easy mode. My point is that top gear (5th) should be relaxed at hwy speeds and Tq curve should be broad enough and flexible so that the car is a killer without a need for a double down shift.

Allard DID make a hemi version for those rare 1/4 mile types in UK, but I don't see that as enjoyable vintage roadster to take to a cruise in. Folks make a 383 will a DART block, (alloy block and heads).

Edelbrock makes a 350 that makes 440 HP at 6k, 425 TQ at 5k, 6500 red line.

Instead of a 9 sec car with massive traction problems a 12 sec car with a broad TQ curve and comfortable easy cruise may be more fun to own.

If we get the gearing figured out, it may help with the motor selection.

What ever happened to Cleveland blocks? Are they dirty from an emissions point of view? Maybe a 351C or a 400C? The car has no aerodynamics and would be miserable a high speeds.

DART makes an Alloy 351 Short Block and alloy 351W heads, could be fun.

Tim

The Chevy 383 has a very nice torque curve. When my buddy had the 500+ HP > 383 built (to replace a built 350), he dropped his rear gears from 4.10 to 3.73, since the torque band was so much wider. IIRC, the old Cleveland 351 is pretty rare, and hasn't been used in many years. The newer 347s & such are all based on the Windsor blocks. Engine building technology has changed a lot over the years. Now, strong torque engines are the rule. I have heard of some roller cams with huge lifts, but still milder durations and overlap.

Ron Porter

General theory is one can tolerate a wilder cam if you use a lot more gear and have a very light car. I am thinking of going the other way.  A light car, milder cam, more displacement, tall gears, enough TQ to pull a fire hydrant out by the roots. 

I don't wanna shift 3 time in a city block. I like my friends 454 pickup. If you have enough TQ you don't need a lot of gears changes.  A 1952 British coupe with competition windscreen would flog you to death at 100 mph anyway.

Say I put in a mild cam 500 CID caddy, make the final gear it tall, with wide gear choices.  Anytime I get in a roll-on situation I don't have to down shift, just throttle steer the corners. That is an extreme example but an illustration of the direction I think I could go.

Damn, you and I are agreeing, get Don to sign on and we will have a trifecta!!

Tim

Our 57 Chevy (in 1972) weighed about 2800# and had a 350 Chevy with FI cam, 3x2 barrels and 4.11 gears.  It was easy to drive.

My 63 Nova weighed 2900# and had the 283 with wild Crane cam, 850 Holley and 4.88 gears.  It was easy enough to drive but you could tell it had some cam in it.

> General theory is one can tolerate a wilder cam if you use a lot more gear and have a very light car.

Issue is that you don't need a big, heavy motor like a 500 Caddy, or a BB Chevy or Ford to get good torque, especially in a light body. As I said in the previous post, engine building techniques can pull a very broad torque band from a 350-400 ci motor, and in a very light car, even 300-350 ci would work. Of course, a 5-liter-sized motor is usually no lighter than a higher-cube variant (thinking SB Chevy & Ford here).

Having an engine with a flexible power band that will go out to 6-6,500 would be good. Personally I find engines that redline in the 5-5,500 range to be both boring and frustrating to drive.

Ron Porter

Ron you are frightening me, our thoughts are converging.

1) what block I get should have as much reasonable displacement as possible for the block weight. Why put in a 307 or 283 when a 383 weighs the same?

2) I don't need a 454, 440 or 460 for acceptable TQ,

3) Huge valve all peak HP drag motor is NOT preferable to a wide strong TQ band for a very light car.

4) (hurts to say this) I agree with you and Jim, go FI, if that means I can cruise at 800 rpm in top gear with AC on. Give up 15% peak HP and 9 sec ET's for flexibility, reliability and drivability.

Short list looks like 351W, 383 chebby or 360 mopar.

Maybe 3.15 ~ 3.27 final gears, ultra wide ratio mix box?

1000 rpm in top gear at 65 mph?

Tim

FYI

Using Desktop Dyno, then desktop Drag

assume race wt 2500#
Chevy 383 397HP@6500 346Ftlb@5500
3.54 final
15 sqft frontal area ,6 drag coff
8" x 24" tires

Attached is an example of a decent torque curve that can be had with a Windsor. Also they can be stroked all the way up to 440 with about $2000. I tend to like the Caddy 500. There's just something about running 2.78 gears getting 24mpg and being able to shred the tires. Or maybe it's that with a few mods and not to much $ you can crank out over 500hp at around 4,500rpm and 575lb-ft at 2,600rpm. Very flat (and very high) hp and torque curves. Oh yeah all that on just 10:1 compression. I can't for the life of me remember what one weighs but iirc it's 50+ lbs lighter than a 454. Of course if your looking for high revs forget it. You turn one of these babes over 5000 grand and you will through a rod or at the very least wreck the valve train.

Jason Barker

Very nice (but I'd like to see the curve down to at least 1500 RPM)! - Jim

Ford Racing, Through Summit Racing, has a Tasty 392 Long block Windsor. All New. All Done. That would be the same weight block as a 351 with around 11% increase in displacement. Several guys in my T-bird Forum are piddling with them right now - You wanted torque and lightweight? All the regular Windsor stuff bolts right up too. The Chebby stroker is STILL cheaper to do, but Ron IS right - The Ford stuff pricing is getting CLOSER to the Bowtie prices. Also, It is Poor Form IMHO, to worry about a little Torque or HP or Drivability or FI vs Carbonators. Kind of a Fly Sh!t in Pepper sort of thing. The car is like 11 pounds - Its gonna FLY no matter WHAT you put in it. The car is NOT a daily driver type car so reliability is nice but NOT imperative. First and foremost it is a COOL RIDE. I'd Focus on COOL. 8 Webbers are incredibly hard to get running right but are equally satisfying when you lift the hood at a meet. Who's jaw DOESN'T Drop? I'd be surprised to see a car like this driven 4000 miles a year - WHO CARES about "Practical"? Get what you want, as raw and unrefined as it may be, and ignore the 2% gain of picking out the specs of Fly Sh!t.

Gas Mileage - Puh-LEEZE ! ? !

Eric Lehmann

Back in my youth (30 years ago), there was an Amsoil dealer near Pittsburgh who had an interesting story and an interesting car.

Remember Gulf Oil was headquartered in Pittsburgh, and this guy had a job with Gulf research.

One day Ford announced they were no longer racing , parked the GT40s, and within hours he was out of work. Being from PA he left that day with DOHC heads, Webber intake ect.

Took it all home where his 289 AC cobra lived. And almost over night ....

We all have DOHC V8's now; but in the early 70's to see a the small AC Cobra driven on the street was a trip, to open the hood and see the down draft Webbers and the DOHC was orgasmic - even for a chebby guy like me.

---------------

Something nice about a big block now that everyone has a Honda.

You open the hood, dumb guy asks "What is that?" You say "Valve cover".

Then he goes over to the other side and asks "What is that?" You say "The other valve cover".

Something about 2 chrome valve covers 3 feet apart that makes them feel very small. Keep those Eclipse owners with huge exhaust tips on the sidewalk where they belong.

--------------------

A decade ago the choice would be obvious, small block Chevy. In the last 10-15 years of 5.0L and 4.6L Mustang the small block Ford engine has become it's own industry and a viable alternative. DART now makes alloy Windsor blocks and heads.

What surprised me is no one is cheering for the 360 Mopar. Lb for Lb, Inch for inch, one of the hardest running small blocks one can run.

Mopar used a high nickel content block that makes it very strong, while a Ford block under the same conditions will crack and chebby will distort like cooked pasta.

------------------

I am worried Eric, you are understanding what I want, Lawdy, Lawdy. Eric, Ron, Don & Tim all on the same page?

Problem is you are far more eloquent than I am in expressing it.

;-)

Tim

> > Gas Mileage - Puh-LEEZE ! ? !

New Allard has an 18 Gal fuel tank. Original had an optional 40 Gal competition tank.

BTW, I never worked on Webbers, worked on almost everything else.

The definition of a typical 60's era V8 is Torque.

What new technology has let us do is allow better control of the ignition and fuel to let engines run a wider rpm range than ever before. Then add in variable cam timing (still in VERY few vehicles) and you are starting to get to an ideal internal combustion engine.

What will make the ideal possible is variable duration and lift without a cam. IT will appear soon in diesels and trickle down to gas engines as the new technology becomes able to deal with higher rpms in gas engines.

What is amazing though, is that 50's and 60's era engines are so close to what is being accomplished today, in the realm of MPG and power. There has been good progress, as there should be, but considering over half a century of "progress" the old engines aren't that outdated.

All the extra gears have allowed a big part of any MPG progress that has been made. More tranny gears mean you can run high rear gears and still have decent response down low. When gas was below 50 cents a gallon, squeezing the last .5 mpg out of a car wasn't any priority.

Don Mallinson

A buddy of mine has a full nickel 434 small block for sale if you're looking for lots of displacement from a smallblock. :o)

Ryan

One way to keep things simple and cheaper, plus getting what you want, would be to get:

A complete 4.6 Cobra motor, either n/a or the newer s/c. A complete Chevy LS-1 setup

Get the complete motor & electronics, then spend a few $$$ to do some polishing and/or chroming. These would be dependable engines, with good tranny options, and their 300-400 HP would work well in a light vehicle.

The cost of getting a 360 or a 383 built are higher, and these engines do damn well right out of the box.

When you have an interesting car body wrapped around the engine, that will attract a lot of attention, and just having a very clean & shiny engine compartment will work well. The extra "bling" of multiple carbs isn't needed at this point, nor the associated tuning and performance issues

Ron Porter

(answer to Jason Barker above)

Well, the 454 is a heavy engine, so 50#  lighter isn't saying much.

Engine technology as come a long way. You can get the cubes in a basic small-block package (as in the new Z06 small-block 427).

An engine with a flexible rev range through at least 6K is just more fun to drive!!

Ron Porter

The last part of that sentence can be easily done with a V8 SHO BTW, as I know from experience.... Worst part is my wife can SHOw you exactly how it works. Granted it didn't come out by the roots but broke off very cleanly....

Scott

On Sat, 12 Mar 2005 21:45:49 -0600, BTJ <btj@insightbb.com> wrote:

> A light car, milder cam, more displacement, tall gears, enough TQ to pull a fire hydrant out by the roots.

One of those Rare Celestial Alignment Thingies. Probably should run out and Buy a Lotto Ticket.

:-) E1

On Sun, 13 Mar 2005 13:50:24 -0600, btj <btj@insightbb.com> wrote:

Lawdy, Lawdy. Eric, Ron, Don & Tim all on the same page? > > ;-) > > Tim

Have you seen the DOHC 4.6 Cobra motors? IMHO, they look very cool & impressive with the big valve covers. Polish or chrome them up, and they look more impressive than an old Hemi valve cover.

The 5.4 engine is even physically larger. Another cool combo would be the 300 HP engine out of a Navigator. It is a 5.4 engine with the DOHC Cobra heads. THAT would be a sweet setup, also!

Ron Porter

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