Why are todays 6cyl so much more powerful?

[jlopes]

I was reading this forum regarding increasing horsepower, when I hear a car commercial talking about a 350+ horsepower non-turbo 6 cyl car. So I start to think what makes today's car create so much more power than the cars of old. Even with the aluminum head, headers, 4 barrel carbs, etc our normally aspirated engines top out in the mid 200's HP's.

So what is the reason for this? Can all this extra power be attributed to EFI and fuel management?

 

[Lazy JW]

It's mostly in the breathing of the modern heads; overhead cams, four valves per cylinder, efficient combustion chambers, etc.

To make power you must be able to move lots of air, mix it with a precise amount of fuel, burn it efficiently, and then get rid of the exhaust. Then do this over and over, very quickly.

Modern EFI doesn't hurt, but it's gotta breathe first.
Joe

 

[fordconvert]

The big thing (other than the modern technology JW mentions) is look at the RPM's they get those peaks at. 90% of the time they are peaking at some crazy high rpm that you would not likely even be able to reach under normal conditions. What good does 350 horse do at 7000 rpm? At 3-4,000 they may be only 200. Our inlines have their torque peaks pretty darn close to the rpm range we run them in so we get to 'use it' instead of brag about what it says on paper.

 

[Asa]

modern engines have the advantage of being almost completely computer modeled, with a computer model you can test out the advantage of this modification, or that restriction, or what happens if i advance the cam timing this much?

you get to build an engine, then let it run and get approximate power numbers from it without ever touching an actual piece of iron or aluminum
this saves time, money, labor, all sorts of everything, so the manufacturers get to build a better engine for less

 

[rocklord]

The 6 cylinder in my 2008 BMW is a NA three liter with 10.7 CR, dual overhead cams, four valves per cylinder, variable valve timing, magnesium block, aluminum head, multi port FI, tuned exhaust, and more computer power than I want to think about. This engine churns out 194 kW , 260 HP SAE @ 6,600 rpm; 225 ft lb , 305 Nm @ 2,750 rpm.

This engine in a 4000 lb, all wheel drive SAV (Sport Activity Vehicle, BMW speak) with a 6spd transmission will do 0-60mph in 6.9 sec and deliver 16 MPG city / 24 MPG highway.

Don'cha love six cylinders.

 

[fordconvert]

Its that torque peak at 2750 that does it. Small displacements are not going to get anywhere near that low in the RPM range.

 

[Eric Rose]

Yeah, the main things about the new engines are the computer aided design and the way they can use the computers to calculate maximum efficiency.

But our straight sixes were pretty crude even when they were brand new, mainly to keep costs down and make everything durable and simple enough that a shadetree mechanic could fix it (because factory warranties were only 3 years at best back then). If you look at what the Europeans were offering then (overhead cams, multi-valve heads, etc) our sixes were a joke. Even Pontiac was offering an OHC six by the late 60's.

Those were also the days when we sent 3 guys to the moon in a craft with less computer power than a digital wrist watch has nowadays.

 

[Anlushac11]

8)

While researching BMW M3's high performance inline six for ideas I was surprised to find that alot of the guys hopping up their M3's were nowhere near 300hp and chassis dynos were much closer to low to mid 200hp range.

Makes me wonder if there is a certain amount of custom tuning going on for engines that are used for rating tests. Not that that has ever been a history of a vehicle engines making more or less than advertised.

I firmly believe if you took our precious little 200, used a aluminum head, and built it using all the modern technology to squeeze the most power like dry film lubricants on mains, rods, and piston skirts, EFI, etc we could make big power too.

 

[Eric Rose]

The gains available from the cylinder head alone have been shown with the aluminum head. If it hadn't been limited to existing intake/exhaust port configurations who knows what kind of power it might have produced.

Also, you could go all out with ultra-light forged aluminum rods (Crower will make pretty much anything you want if you have the dough) and custom composite coated pistons with the thinner rings the new motors are using. I think Mike is even working on a roller cam setup.

 

[rommaster2]

Just look at Mraleys engine, in all reality its not too extreme of a build and when dynoed it was putting out i believe 214 at the wheels around 5500 or 600 rpms. Thats carburated and still more then 1 hp per cubic inch at the wheels. Supposedly (at least what the main site says) he gets 26 to 27 miles per gallon still.

The new aluminum head has put a new lease on our cars, making great numbers available (at a cost) to the everyday man who doesnt have a machine shop to create his own intake manifold.

 

[addo]

There are some aspects to contemporary motors that we can't build into an older six. Thermal modelling in design of coolant jackets, for example. Nor can we really change the rod ratio or squareness if they're out of kilter with modern practice.

Funny thing is, I am sure that if a DOHC quad valve bolt-on kit were developed, people would still ask if there was a manifold to fit the Holley 650 because EFI seems too hard. :roll:

...350+ horsepower non-turbo 6 cyl car

Oh, and I call total BS on the originally mentioned advertisement figures. Advertising "licence" - nothing more.

 

[Anlushac11]

Nor can we really change the rod ratio or squareness if they're out of kilter with modern practice.

I dont have the money to do it at this time but did look into offset grinding and destroking the 200 by using Honda 1.889" rod journals and custom longer rods.

I just dont have the money to pursue it at this time.

Also wanted to polish and knife edge the crank but again $$$

 

[xctasy]

The problem with later 200 and 250 sixes is one carb feeding six ports, a low rent cam less than 256 degrees, and lastly, the heads air flow flow at a valve lift of less than 0.4" is very low.

A modern engine makes power by:-

1. Port injection, ignition and exhast optimization first,
2. then cam shaft optimization
3. and then lastly, head design.

Running port on port carbs, a wild cam, and a better head design will take the engine power up to any current engine, and its been proven with 2 valve per cyclinder NASCAR and Prostock engines. A 350 cubic inch engine running at 7500 rpm can make over 650 hp.

Even considering the time it was released, the Ford I6 was no pargon of power. For every revolution of the engine, the 200 Ford six produces about the lowest specific output of any engine bar a side valve Ford V8. To have a 200 cube engine reving to only 3600 rpm to get only 83 hp is just like a 400 cube engine reving to only 3600 rpm giving 164 hp,
or a 351 cube engine reving to 3600 rpm only giving 145 hp.

The very same 351 engine can end up giving 650 hp at 7500 rpm with just carb, cam and head modifications

Another example. A US 1980 Granada 4.1 1-bbl gave about 95 hp at 3600 rpm. The same basic 4.1 engine block in a 1987 Australian Falcon, with EFI, a 264 degree cam, and a cross flow head gave 164 hp at 4000 rpm.

So a 72% power gain can be had just by attention to those three parts on induction, cam and head flow.

This has been proven time and time again with lowly 83 hp net 3.3 engines suddenly yielding 145 hp with just induction, cam and head flow improvements. In Australia, 4-bbl I and L-6 engines in the 250 to 265 cube mark were making 195 hp to 216 hp gross in 1970. Similar to the 230 and 250 cube 4-bbl OHC Pontiac engines around the same era.

 

[xy500]

In Australia, 4-bbl I and L-6 engines in the 250 to 265 cube mark were making 195 hp to 216 hp gross in 1970. Similar to the 230 and 250 cube 4-bbl OHC Pontiac engines around the same era.

AHEM!
the 265 you speak of made over 300hp gross!
the hottest aussie six ever i reckon

 

[ellum]

But our straight sixes were pretty crude even when they were brand new, mainly to keep costs down and make everything durable and simple enough that a shadetree mechanic could fix it (because factory warranties were only 3 years at best back then).

Good point. I think with stock hp our old 200ci will just last forever.

Regards
Elvis

 

[Anlushac11]

In Australia, 4-bbl I and L-6 engines in the 250 to 265 cube mark were making 195 hp to 216 hp gross in 1970. Similar to the 230 and 250 cube 4-bbl OHC Pontiac engines around the same era.

AHEM!
the 265 you speak of made over 300hp gross!
the hottest aussie six ever i reckon

But only with very limited production side draft weber carbs.

That said, I would kill to have one of those Chargers if I could afford it.

 

[Funky Cricket]

well, think about it this way.

Get an aluminum head (cross flow, sorry mike, your is awesome, but we want to make it a closer comparison), a modern EFI port injection and tuned intake, lighter pistons and a better stroke/diameter ratio, 4 ports, overhead cams and a computer that can maximize a/f ratios in millionths of a second. Put all this on our 6. how much power would it make.

alot.
we have seen with nothing more than a turbo on a completely stock 80 engine make power numbers close to that.

also don't forget those advertised numbers are gross and in a lab with minimal accessories. Are engines aren't great, but put some modern tech on them and be creative and they can compete with modern engines, they won't ever be wild power monsters like a twin turbo supra, but your old sony trinitron bubble tv (the pride of the late 80's) will never be a 60" plasma flat screen. we aren't running a 1960's econo engine because they are known for their crazy power potential, we are running them because we're crazy.

 

[FALCONAROUND]

well, think about it this way.

We aren't running a 1960's econo engine because they are known for their crazy power potential, we are running them because we're crazy.

AMEN to that! I'm building my iron head 200 to be a dual 2V intake, and I'm gonna make 250 HP naturally aspirated or I'm gonn eat my pancakes!

 

[CobraSix]

Engines are always getting better and more efficient (either more economy or more power per displacement) and it doesn't take decades, only a few years. My wife's 99 Mustang with a V-6 is advertised as having only 20HP less then my friends 96 Mustang GT with the 4.6L V8. Heck, today's 4.6L V8s are doing better then 10 years ago.

It's akin to asking why the first computer took up an entire floor and still doesn't have the power that your cellphone does now.

 

[xctasy]

well, think about it this way.

Get an aluminum head (cross flow, sorry mike, your is awesome, but we want to make it a closer comparison),

Point taken for comparison, of course.

I've done some research on 2 valve per cylinder non X-flows, and the heat conductivty in a non cross flow engine improves its fuel economy, and only marginally hurts power. The Lamborghini LP 400 V12 was technically non Cross flow, and the non cross flow Holden L6's (201 cubic inces) got right down to 295 hp at 7500 rpm. Same with the alloy head Healy 3000's, and the 240z's, and the early non cross flow 1500 cc Ford "Kent" engines (on which the Datsun Z-series engine block was based) were able to crank out some brilliant numbers. .And the non cross flow A and B series engines were standout performers modified, even when the intake ports were disasters.

Engines are always getting better and more efficient (either more economy or more power per displacement) and it doesn't take decades, only a few years. My wife's 99 Mustang with a V-6 is advertised as having only 20HP less then my friends 96 Mustang GT with the 4.6L V8. Heck, today's 4.6L V8s are doing better then 10 years ago.

It's akin to asking why the first computer took up an entire floor and still doesn't have the power that your cellphone does now.

Actually, the mechanical efficiency is the same as it ever was. Inspite of a 10 to 15% loss in peak power due to emissions, there has been an approximate 1.3% power growth per year over the last 34 years, but a 3% growth in power per year over the last 76 years. The gains have levelled off.

The best engines are getting no better, the average enigine is improving but that improvement is leveling off. All due to EPA constraints.

For example, a 1974 3.9 Liter Lamborghini LP400 had 375 hp at 8000 rpm, and today, a fully emissions Falcon 4.0 engine has 262 hp at 5250 rpm. For every rpm, an Aussie in line six has as much proportionally about 6% more power for each revs and cubic inches. Doing some math, the Lambo had an Aspirations Index of 5120 ((239cube*8000rpm)/375 hp = 5120)).
A 2008 Falcon has 4869 ((240cubes*5250rpm)/262 hp = 4869)

For Aspirations Index, see below

However, the range between factory net power ratings for Lamborghinis and Ford Falcons in 1974 showed that the Falcon 250 yielded only 155 gross hp (127 hp net) at about 3600 rpm. The Aspirations Index was 7086 ((250cubes*3600rpm)/127 hp = 7086).

So the mass produced cars are now better than, if not as good as, the specialist cars 30 odd years ago. The power improvement for every rev and cube of engine in the Intermediate Fords is about 45%, or 1.3% more power every year for the last 34 years.



Aspirations Index is a term for efficiency. In a non metric environment, it's best determined by ((A cubes Times[*] B rpm)/C hp [net flywheel figures]) This gives = Ai [a real number].


See how real specific power for every rev and cube has improved

When its calculated on a 1932 221 Flathead Ford, its as high as 11 500.
A smog spec 1980 4.2 Mustang V8 has 9643
A smog spec 1980 3.3 Mustang L6 has around 8675
A smog spec 1980 5.0 LTD V8 has 8427
We have an pre emissions Aussie 250 Falcon (1974) 1-bbl with 7089,
A smog spec 1985 5.0 HO EFI has about 6174
A smog spec 1985 4.1 EFI Falcon has about 6097
A 74 De Tomaso GT5 with its Cobra Jet HO 351 has 5760
An 89 SHO Taurus has 5157
An LP400 Countach (1974) with 5120
A smog spec 1992 4.0 SOHC Falcon XR6 has about 5058
A 243 2008 Falcon EFI Twin Cam VVT with 4869.
The best non supercharged US 5.4 engine, a DJR 320 Falcon, gives almost 4000.
A NASCAR would run about 4000.
Interestingly, the 183 cube F1 engines reving to 18000 rpm, and getting 850 hp, got only 3875.
When its calculated on a 302 EFI V-eight Supercar, its as low as 3600.


Of course, when you add a turbo with a boost ratio of 1.5 times atmospheric pressure, you end up with Aspirations Ratios like 3250 or less for a modern Twin cam Turbo's like Skyline R34's and F6 Falcons. The addition of 5.5 times the atmospheric boost in the 1986 BMW F1 engines made 1500 rpm at 11000 rpm from just 91.5 cubes, and AI of just 671, a record not surpassed.