Increased Torque

[journeyman]

Rather new here...
I have a tired 454 FI (obd1) and would love to increase the torque and overall efficiency.

My application is low rev (never sees 4500 RPM).
Naturally I am thinking about long strokes and small bores... Question: Would running 4.75" crank in a 3.935" (366T) bore make sense? displacement will be similar (462 ci), so the stock FI system should function correctly (use the stock manifold with spacers for the 10.2 block), and SMOG ( I am in CA) should not be an issue, since smaller bores idle cleaner than bigger bores...

My goal is to shift the torque curve lower and improve thermal and mechanical efficiency in the 1800 - 2800 RPM range.

Does this make sense?

 

[grumpyvette]

I think your placing a bit more emphasis, on the bore/stroke ratio than it really deserves , especially at low rpms.
you also will find your very unlikely to fit a 4.75" stroke crank into a 366 block due to clearance issues and required grinding.
torque produced has more to do with the total EFFECTIVE DISPLACEMENT, COMPRESSION RATIO and cam timing.
If I was going to build a torque monster , starting from where you are,Id consider rebuilding the 454 either as a 454 or as a 496 stroker with a 4.25" stroke crank,and boosting the compression to about 10:1, swapping to mildly ported peanut port heads and have a long talk with the cam tech guys at several cam company's like crane and crower.
you'll generally find that you'll produce about 1-1.2 ft lbs of torque per cubic inch of displacement in a well designed non-supercharged engine, remember TORQUE is generated by pressure on the piston surface and the cranks leverage, but its also effected by the pressure curve in the cylinder and a larger diam. piston has more surface area for the pressure to push against, remember the typical pressure curve has easily 80% of the useful pressure in the first 2" of the stroke of the piston moving away from TDC.
slap a some 1 3/4"-1 7/8" inch headers and a low restriction exhaust on the car/truck, your power will be restricted above 4000rpm but youll see improvement from idle to 4000rpm

tricks like back cuts on valves increase low rpm and low lift flow, and factors like header primary length ,collector design for increased scavenging and matching intake port cross sectional area to the intended flow rate, and cam timing are critical

y David Reher, Reher-Morrison Racing Engines

“An engine produces peak torque at the rpm where it is most efficient.”

Recently I’ve had several conversations with racers who wanted to build engines with long crankshaft strokes and small cylinder bores. When I questioned them about their preference for long-stroke/small-bore engines, the common answer was that this combination makes more torque. Unfortunately that assertion doesn’t match up with my experience in building drag racing engines.

My subject is racing engines, not street motors, so I’m not concerned with torque at 2,000 rpm. In my view, if you are building an engine for maximum output at a specific displacement, such as a Comp eliminator motor, then the bores should be as big as possible and the stroke as short as possible. If you’re building an engine that’s not restricted in size, such as a heads-up Super eliminator or Quick 16 motor, then big bores are an absolute performance bargain.

I know that there are drag racers who are successful with small-bore/long-stroke engines. And I know that countless magazine articles have been written about “torque monster” motors. But before readers fire off angry e-mails to National DRAGSTER about Reher’s rantings on the back page, allow me to explain my observations on the bore vs. stroke debate.

In mechanical terms, the definition of torque is the force acting on an object that causes that object to rotate. In an internal combustion engine, the pressure produced by expanding gases acts through the pistons and connecting rods to push against the crankshaft, producing torque. The mechanical leverage is greatest at the point when the connecting rod is perpendicular to its respective crank throw; depending on the geometry of the crank, piston and rod, this typically occurs when the piston is about 80 degrees after top dead center (ATDC).

So if torque is what accelerates a race car, why don’t we use engines with 2-inch diameter cylinder bores and 6-inch long crankshaft strokes? Obviously there are other factors involved.

The first consideration is that the cylinder pressure produced by the expanding gases reaches its peak shortly after combustion begins, when the volume above the piston is still relatively small and the lever arm created by the piston, rod and crank pin is an acute angle of less than 90 degrees. Peak cylinder pressure occurs at approximately 30 degrees ATDC, and drops dramatically by the time that the rod has its maximum leverage against the crank arm. Consequently the mechanical torque advantage of a long stroke is significantly diminished by the reduced force that’s pushing against the piston when the leverage of a long crankshaft stroke is greatest.

An engine produces peak torque at the rpm where it is most efficient. Efficiency is the result of many factors, including airflow, combustion, and parasitic losses such as friction and windage. Comparing two engines with the same displacement, a long-stroke/small-bore combination is simply less efficient than a short-stroke/big-bore combination on several counts.

Big bores promote better breathing. If you compare cylinder head airflow on a small-bore test fixture and on a large-bore fixture, the bigger bore will almost invariably improve airflow due to less valve shrouding. If the goal is maximum performance, the larger bore diameter allows the installation of larger valves, which further improve power.

A short crankshaft stroke reduces parasitic losses. Ring drag is the major source of internal friction. With a shorter stroke, the pistons don’t travel as far with every revolution. The crankshaft assembly also rotates in a smaller arc so the windage is reduced. In a wet-sump engine, a shorter stroke also cuts down on oil pressure problems caused by windage and oil aeration.

The big-block Chevrolet V-8 is an example of an engine that responds positively to increases in bore diameter. The GM engineers who designed the big-block knew that its splayed valves needed room to breath; that’s why the factory machined notches in the tops of the cylinder bores on high-performance blocks. When Chevy went Can-Am racing back in the ’60s, special blocks were produced with 4.440-inch bores instead of the standard 4.250-inch diameter cylinders. There’s been a steady progression in bore diameters ever since. We’re now using 4.700-inch bores in NHRA Pro Stock, and even bigger bores in unrestricted engines.

Racers are no longer limited to production castings and the relatively small cylinder bore diameters that they dictated. Today’s aftermarket blocks are manufactured with better materials and thicker cylinder walls that make big-bore engines affordable and reliable. A sportsman drag racer can enjoy the benefits of big cylinder bores at no extra cost: a set of pistons for 4.500-inch, 4.600-inch or 4.625-inch cylinders cost virtually the same. For my money, the bigger bore is a bargain. The customer not only gets more cubic inches for the same price, but also gets better performance because the larger bores improve airflow. A big-bore engine delivers more bang for the buck.

Big bores aren’t just for big-blocks. Many aftermarket Chevy small-block V-8s now have siamesed cylinder walls that will easily accommodate 4.185-inch cylinder bores. There’s simply no reason to build a 383-cubic-inch small-block with a 4-inch bore block when you can have a 406 or 412-cubic-inch small-block for about the same money.

There are much more cost-effective ways to tailor an engine’s torque curve than to use a long stroke crank and small bore block. The intake manifold, cylinder head runner volume, and camshaft timing all have a much more significant impact on the torque curve than the stroke – and are much easier and less expensive to change.
read these and sub links
viewtopic.php?f=52&t=2787&p=7220&hilit=volumetric#p7220

viewtopic.php?f=52&t=2782&hilit=+volumetric

viewtopic.php?f=53&t=3894&p=10311#p10311

now if you really want to build torque you could rebuild the engine similar too what I listed above but drop the compression to about 8.5:1 and add a turbo, you could very easily add more than 200 or more extra ft lbs of torque to that 454-496 bbc with a correctly matched turbo.
if your serious you might want to go with a large DISPLACEMENT TURBO DIESEL , which can easily produce over 600-700 ft lbs of torque

 

[journeyman]

OK, that makes sense, but From what I have seen, there isn't that much difference in cost from a 4.25" rotating assy and a 4.75.
The 4.75 was listed for the 10.2 block, so it would seem that it should work on the 366 unless the bore is too small (clearance issues).

Would I expect a significant increase in combustion efficiency at low RPM (1800 - 2800) in a 3.935 x 4.75" engine over a 4.25 x 4"? Both have very similar displacement. Obviously that question assumes optimized cam duration, overlap and lift in both cases as well as compression ratio.

Where is all this coming from?
I have always heard that longer strokes produce more low end torque. Also that low end torque engines tend have a higher thermal efficiency (at low RPM's).

I read your compilation on quench and combustion. It seems that has much (more?) to do with efficiency than bore and stroke.

 

[grumpyvette]

like I stated, your very likely to have clearance issues fitting a 4.75" stroke crank in a O.E.M. tall deck block
most guys using 4.75" stroke cranks use AFTERMARKET DART BLOCKS, with wider internal clearance
a 496 big block thats been built correctly with decent compression will have very impressive low and mid rpm torque.
keep in mind many 454 truck engines came with about a true 8.4:1 compression
boosting the compression to 10:1 would with no other changes increase torque by about 6%, swapping to a 496 displacement should add at least 50 more ft lbs of torque

look closely at the block dimensions
a 4.75" stroke crank with its 2.20" journals even without connecting rods installed would exceed a 4.575" rotating diam.
add connecting rods and Id be very surprised if its less than 6", from experience I can assure you that even a 4.25" stroke crank and rods frequently requires minor clearance grinding adding an additional .250 inches to the clearance work will most likely get you into trouble

 

[journeyman]

Although a little confused by the drawing (unclear where the obstacles are for the rotating diameter), what you are saying makes complete sense to me. Question: I know that a 4.25" crank will drop into a 9.8 block with no (or minor) clearance issues, what is the maximum stroke that can be dropped into a 10.2" block with no/minor clearance issues? This question is more theoretical for me as I am starting to see the light in the wisdom of staying with the 9.8 block.

The tempting part for me on the 4.75 stroke with the small bore was keeping the stock injection system (no mods) and insuring SMOG compliance. In other words, reconfiguring the stock displacement of 454 - 462. It sounds like although a cool concept, it would not be at all practical if a custom ordered block was required.

 

[grumpyvette]

the longest stroke crank that will normally fit the stock blocks "WITH CLEARANCE GRINDING REQUIRED" is the 4.375" stroke in my experience. and that requires steel rods contoured for minimal clearance work, aluminum rods being larger and requiring more clearance won,t generally work.
if you check around you'll find a few guys have managed to squeeze in a 4.5" stroker but several guys I know who have tried ruined blocks, youll generally find that a 4.25" stroke is all thats required in a OEM 454 block and longer strokes don,t really gain you much more than added expense and lower durability.
I see a few guys have successfully adapted turbo chargers to the 366 big block engines to produce impressive mid rpm torque, that might be an option

READ THIS
viewtopic.php?f=53&t=6430

personally IVE always preferred the tall deck blocks when building a 496 but IM in the minority, Ive used the scat 4340 forged crank rotating Assembly with 6.385" rods and 7/16" rod bolts , look thru the linked info theres a dozen or more good combos listed
CHEVY: Rotating Assemblies
CHEVY BIG BLOCK 4340 FORGED ROTATING ASSEMBLIES
CHEVY 454 BIG-BLOCK 2-PC REAR SEAL 454 MAIN, 4340 FORGED CRANKS, H-BEAM RODS WITH 7/16" CAP SCREWS, obviously gearing and compression heads,intakes etc. change your cam choice so talk to CRANE AND CROWER AND ERSON about your cam choice once your sure of those components


http://www.scatcrankshafts.com/

CI Crank Rod Piston Boresize Type 58cc 64cc 70cc Inclcrp Inclcrprb Compl
460 4-454-4000-6135 2-454-6135-2200 FORGED 4.280 FLAT 8.9 8.4 8.2 1-42005-1 1-42005 1-42005BE
460 4-454-4000-6135 2-454-6135-2200 PREMIUM FORGED 4.280 FLAT 8.9 8.4 8.2 1-42010-1 1-42010 1-42010BE
460 4-454-4000-6135 2-454-6135-2200 FORGED 4.280 DOME 13.7 12.8 11.9 1-42055-1 1-42055 1-42055BE
460 4-454-4000-6135 2-454-6135-2200 PREMIUM FORGED 4.280 DOME 13.7 12.8 11.9 1-42060-1 1-42060 1-42060BE
460 4-454-4000-6385 2-454-6385-2200 FORGED 4.280 FLAT 8.9 8.4 8.2 1-42105-1 1-42105 1-42105BI
460 4-454-4000-6385 2-454-6385-2200 PREMIUM FORGED 4.280 FLAT 8.9 8.4 8.2 1-42110-1 1-42110 1-42110BI
460 4-454-4000-6385 2-454-6385-2200 PREMIUM FORGED 4.280 DOME 14.0 12.7 11.7 1-42160-1 1-42160 1-42160BI
489 4-454-4250-6135 2-454-6135-2200 FORGED 4.280 FLAT 9.4 9.0 8.6 1-42255-1 1-42255 1-42255BE
489 4-454-4250-6135 2-454-6135-2200 PREMIUM FORGED 4.280 FLAT 9.4 9.0 8.6 1-42257-1 1-42257 1-42257BE
489 4-454-4250-6135 2-454-6135-2200 PREMIUM FORGED 4.280 DOME 10.5 10.0 9.5 1-42260-1 1-42260 1-42260BE
489 4-454-4250-6385 2-454-6385-2200 FORGED 4.280 FLAT 8.9 8.5 8.2 1-42305-1 1-42305 1-42305BI
489 4-454-4250-6385 2-454-6385-2200 PREMIUM FORGED 4.280 FLAT 9.4 9.0 8.6 1-42310-1 1-42310 1-42310BI
489 4-454-4250-6385 2-454-6385-2200 FORGED 4.280 DOME 10.8 10.2 9.7 1-42355-1 1-42355 1-42355BI
489 4-454-4250-6385 2-454-6385-2200 PREMIUM FORGED 4.280 DOME 10.7 10.2 9.7 1-42360-1 1-42360 1-42360BI
CHEVY 540 BIG-BLOCK 2-PC REAR SEAL, 9.780 SHORT DECK 454 MAIN, 4340 FORGED CRANKS, H-BEAM RODS WITH 7/16" CAP SCREWS
CI Crank Rod Piston Boresize Type 58cc 64cc 70cc Inclcrp Inclcrprb Compl
540 4-454-4250-6385 2-454-6385-2200 PREMIUM FORGED 4.500 FLAT 9.8 9.4 9.0 1-42370-1 1-42370 1-42370BI
540 4-454-4250-6385 2-454-6385-2200 PREMIUM FORGED 4.500 DISH 8.7 8.4 8.2 1-42375-1 1-42375 1-42375BI
540 4-454-4250-6385 2-454-6385-2200 PREMIUM FORGED 4.500 DOME 14.8 13.5 12.27 1-42380-1 1-42380 1-42380BI
CHEVY 454 BIG-BLOCK 2-PC REAR SEAL, 10.200 TALL DECK 454 MAIN, 4340 FORGED CRANKS, H-BEAM RODS WITH 7/16" CAP SCREWS
CI Crank Rod Piston Boresize Type 58cc 64cc 70cc Inclcrp Inclcrprb Compl
572 4-454-4500-6535 2-454-6535-2200 PREMIUM FORGED 4.500 FLAT 10.0 9.7 9.4 1-42385-1 1-42385 1-42385BI
572 4-454-4500-6535 2-454-6535-2200 PREMIUM FORGED 4.500 DISH 8.8 8.5 8.2 1-42390-1 1-42390 1-42390BI
572 4-454-4500-6535 2-454-6535-2200 PREMIUM FORGED 4.500 DOME 15.5 13.1 12.2 1-42392-1 1-42392 1-42392BI
572 4-454-4500-6535 2-454-6700-2200 PREMIUM FORGED 4.500 FLAT 10.0 9.7 9.4 1-42395-1 1-42395 1-42395BI
572 4-454-4500-6535 2-454-6700-2200 PREMIUM FORGED 4.500 DOME 15.5 13.1 12.2 1-42397-1 1-42397 1-42397BI
CHEVY 454 BIG-BLOCK 1-PC REAR SEAL 454 MAIN, 4340 FORGED CRANKS, H-BEAM RODS WITH 7/16" CAP SCREWS
CI Crank Rod Piston Boresize Type 58cc 64cc 70cc Inclcrp Inclcrprb Compl
489 4-454-4250-6385-L 2-454-6385-2200 FORGED 4.280 FLAT 8.7 8.4 8.0 1-42405-1 1-42405 1-42405BI
489 4-454-4250-6385-L 2-454-6385-2200 PREMIUM FORGED 4.280 FLAT 9.4 9.0 8.6 1-42410-1 1-42410 1-42410BI
489 4-454-4250-6135-L 2-454-6135-2200 FORGED 4.280 FLAT 9.4 9.0 8.6 1-42450-1 1-42450 1-42450BE
489 4-454-4250-6135-L 2-454-6135-2200 PREMIUM FORGED 4.280 FLAT 9.4 9.0 8.6 1-42452-1 1-42452 1-42452BE
489 4-454-4250-6135-L 2-454-6135-2200 PREMIUM FORGED 4.280 DOME 10.5 10.0 9.5 1-42454-1 1-42454 1-42454BE
489 4-454-4250-6385-L 2-454-6385-2200 FORGED 4.280 DOME 10.5 10.0 9.5 1-42455-1 1-42455 1-42455BI
489 4-454-4250-6385-L 2-454-6385-2200 PREMIUM FORGED 4.280 DOME 10.7 10.2 9.7 1-42460-1 1-42460 1-42460BI
540 4-454-4250-6385-L 2-454-6385-2200 PREMIUM FORGED 4.500 FLAT 10.2 9.8 9.4 1-42500-1 1-42500 1-42500BI
540 4-454-4250-6385-L 2-454-6385-2200 PREMIUM FORGED 4.500 DOME 10.8 10.3 9.9 1-42505-1 1-42505 1-42505BI
540 4-454-4250-6385-L 2-454-6385-2200 PREMIUM FORGED 4.500 DISH 9.8 9.4 9.0 1-42510-1 1-42510 1-42510BI

viewtopic.php?f=51&t=2692&p=14873&hilit=tall+deck#p14873

viewtopic.php?f=51&t=2692&p=8174&hilit=tall+deck#p8174


viewtopic.php?f=87&t=4380&p=11505&hilit=tall+deck#p11505

viewtopic.php?f=53&t=3893&p=10337&hilit=tall+deck#p10337

 

[journeyman]

Grumpy, did you mean in 9.8 blocks or 10.2 blocks? Or are the clearances (for the rotating assy) the same? I have never actually looked inside a 10.2 block, so I don't know...

 

[grumpyvette]

the only major difference, between tall and standard deck blocks cast in the same year, is the deck height, rotating clearance will be very similar or identical, remembers theres a bunch of different block castings in both tall and short deck blocks, all are similar, but not exactly the same, and theres several versions, in basic block designs in both tall and standard deck , mark IV, mark V , mark VI blocks, generally the older pre-1971 blocks are a bit thicker walled but not always,because although the casting may be a bit thicker the control on minor core shift was not as exact


look thru this link

viewtopic.php?f=51&t=93&p=10310&hilit=numbers+casting#p10310

If your serious about building a tall deck block based engine the aftermarket DART BLOCKS are much thicker and well designed, and use a stronger alloy casting, plus you can get larger bore and even taller deck heights

http://www.dartheads.com/products/engin ... locks.html

http://www.dartheads.com/products/aitdo ... ile_id/53/

just the cost of the aftermarket block, will probably prevent your dream project but displacements of over 750 cubic inches are possible... if you can even think.... over the screams of agony your wallet keeps making

 

[journeyman]

Wow, the DART stuff is like Vodka for an alcoholic. Fantasy football ain't got nothin' on fantasy engine building...

Ok, now back to reality.

I think I really do see the light in the 9.8 block. For any reasonable combination and for any reasonable budget, it is the most appropriate. I am a little surprised (shocked?) that the tall deck does not offer any more rotating clearance than the short deck. What a bummer. if only...

I am actually wondering if the most practical option might be the factory HT502 with thinner head gaskets (reduce the quench area) to increase the C.R. from 8.75 to (maybe) 9.5:1 and possibly reduce the cam duration (toward the factory 454 cam) to come up with a high efficiency, low RPM BBC that will have respectable torque to 4500 RPM.

It all comes down to compromises to be practical. I hate the practicality of compromise. I would love to have a FAT wallet, a LARGE credit account at DART and a machine shop that owes me favors...

 

[grumpyvette]

http://ohiocrank.com/chev_bb_shortb.html

http://www.ultrastreet.net/engines/540_ultrastreet.asp

http://www.dougherbert.com/font-colorre ... 675hp.html

a couple options


Volumetric Efficiency -
Manipulating Torque Curves
From the December, 2010 issue of Circle Track
By Jim McFarland

Volumetric Efficiency
Over time, in this column, we have touched upon several aspects of not only how to achieve higher levels of volumetric efficiency (as it relates to torque) but the importance of this feature in a racing engine, particularly for circle track applications. In the course of those discussions, we've attempted to establish an understanding of how induction and exhaust system design and dimensions play into this subject. But before we try to develop topics specific to yet another perspective of how torque curves can be linked with these two major systems, a brief review of a few previously-mentioned points is intended to provide some background information.

For example, we know that in both an intake and exhaust system, we're dealing with pulsating, unsteady flow. We also know that as a particular function of piston displacement and rpm, each system can pass through what we'll call a "resonant" point often associated with a peak torque value. At this particular rpm, both systems are generally the most efficient and can be associated with a certain "mean flow velocity" found at such peaks, regardless of engine combination. We can also label this flow rate as the "critical" velocity.

As each system approaches this flow velocity, there is not sufficient rpm to achieve the rate and beyond peak torque rpm it will exceed that value, thus the shape of a typical torque curve. We also know, from a design standpoint, that each can be treated as a separate system. That is to say each will effectively produce its own torque curve. In reality, they combine to create a "net" or resulting curve shape just described.

It turns out that a third variable influencing at what rpm an engine of specific piston displacement will reach its critical intake or exhaust flow velocity is the cross-section area of the flow path. For the sake of simplicity, let's say these paths are of constant cross-section, neither tapered nor "stepped" as in practice. Actually, for purposes of our discussion, this aspect of the subject is irrelevant. What's important is understanding that it's possible to "tune" intake and exhaust systems separately. Let's restate that suggestion.

On a given engine, it's possible to select passage section areas to achieve peak torque (volumetric efficiency) points at specific rpm where such boosts are desired. Now, let's consider the possible value in having this measure of influence over an engine's torque characteristics.

Suppose we decided to have an intake and exhaust system broaden (or make flatter) a net torque curve. One approach would be to adjust intake and exhaust passages sufficiently different to spread their respective torque peaks farther apart in the rpm range. The net effect of this would be to create somewhat of a "depression" in the curve's shape between the two peaks and, actually, remove some of the net peak torque.

However, the effect could benefit off-the-corner acceleration during the lower engine speeds while having some torque in reserve (higher rpm peak or boost) getting past the flag stand. We're not dealing with "maybe so" issues here, there have been numerous instances where, when reduced to practice, the concept works. There are patents verifying the results.

Now let's take this approach one step further. Building on the same concept that flow passage size, piston displacement, and rpm are closely tied with where in an engine's speed range torque boosts occur. Here's another thought; suppose we configured a set of headers with two sizes of primary pipes for a V-8 engine, choosing to order the pipes in a way that paired every other cylinder with the same size pipe. As an example, if we assume a firing order of 1-8-4-3-6-5-7-2, every other cylinder would be served by the same size primary pipe. Functionally, we will have created a header system that treats the engine like two V-4s, each of which will contribute to the overall torque curve at separate and different rpm, but do so with a flatter "exhaust system torque curve," if you will.


The same approach can be applied to the intake manifold for this same engine. While it may no longer be available from Edelbrock, there was a time several years ago when it produced an early version of its Victor series intake manifold for small-block Chevrolet V-8s that was called the Victor 4X4.

The four inboard runners (Nos. 4, 6, 3, and 5), being shorter in length, were sized larger in section area than the four outboard runners (Nos. 2, 8, 1, and 7). These latter, being longer, were sized with a slightly smaller section area based on a naturally lower tuning rpm because of their comparatively longer length, compared to the shorter inboard runners. By design, the manifold was intended to help broaden or flatten the resulting torque curve and was largely targeted for oval-track engines.

After the manifold's introduction, I distinctly recall a conversation with Junior Johnson who asked if the same approach could be taken with a comparable manifold for the big-block he was using in NASCAR at the time. The conversation included the idea possibly being applied to a header system. I shared with Junior that I'd also done some study on having a camshaft ground with two sets of intake and exhaust lobes (and position on the shaft) to coincide with intentions from the "modified" intake and exhaust systems, further enhancing the "two V-4s" notion for manipulating the torque curve. Post-discussion results indicated he was successful.

What I hadn't shared with him was the fact I was driving (at the time) a then-current model year small-block Chevy Camaro using just such a camshaft. In later years, a short-track engine builder with whom Edelbrock was working adapted the idea to a couple of his customer engines with predictably good results. As it has turned out, this approach to "customizing" camshafts became a method to help resolve cylinder-to-cylinder volumetric efficiency variations by tailoring lobe specifications to compensate for imbalances in torque among an engine's cylinders. That practice continues today.

The overriding point here is that it's possible to configure intake, exhaust and camshaft packages to put torque at more favorable engine speeds than obtainable by some other means. In fact, the ability to identify areas in a given engine speed range where torque boosts can be helpful becomes a tool for matching overall torque curves to gearing and track conditions.

If you accept that the area under the torque curve represents available "work" to propel the car, it's possible to decrease what we'll call peak torque values by shifting torque to rpm where it's more helpful without creating more or less gross torque. We know of specific examples where it was known in what speed range an engine operated most frequently, and then by the methods we've been discussing, torque enhancement was directed to these rpm-not unlike how you might address the same issue with gear combinations but in addition to this approach. Magic it's not.