# Are High-Revving V-8 Engines Needed Anymore? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 19, 2012, 4:39pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513 "2012-11-19T16:39:45Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 12:14am UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/21 "2012-11-21T00:14:49Z")
> [@Machine\_Elf](#): > > All other things being equal, engine output torque is proportional to total engine displacement. So a 5.7-liter V8 will put out about the same torque as a 5.7-liter four-banger (neglecting the difference in torque-versus-RPM curves for the two engines). > > A 5.7-liter V8 will be smoother than a 5.7-liter four-banger, owing to the greater number of (and smaller magnitude) torque pulses per engine cycle. not to mention the 5.7 liter 4-cylinder would vibrate your fillings loose 😛 > [@](#): > > Except it won’t make as much power as the high-revving V8 will. Are you not understanding that a high-revving V8 makes more power than a low-revving V8 of identical displacement? I think a lot of people believe torque and horsepower are independent of each other. which is, of course, untrue. ---
**Author:** ![Throatwarbler\_Mangrove](https://avatars.discourse-cdn.com/v4/letter/t/8c91f0/32.png) [@Throatwarbler\_Mangrove](https://boards.straightdope.com/u/Throatwarbler_Mangrove)\ **Post date:** [November 21, 2012, 1:09am UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/22 "2012-11-21T01:09:29Z")
I will note that in the last 2 years or so there has been somewhat of a sea change in V8 engines, led by BMW. Specifically what has happened is that BMW has replaced it’s entire lineup of V8 engines with a completely new design. The new engine has the flow direction reversed from usual gas V8 engines, with the intake on the outside of the V and the exhaust in the valley. [Picture](http://www.caradvice.com.au/12149/bmws-new-twin-turbo-v8/) This is a layout commonly used on turbodiesel V8 engines that are designed from the ground up to use forced induction. There are many advantages as explained [here](http://autozine.org/technical_school/engine/Forced_Induction_4.html#Cross-bank), but I imagine in the past, using the same design on a gas engine with much higher exhaust temps would have been problematic. AFAIK as it stands now all BMW V8s are of this type and all are turbocharged other than the outgoing M3. There are no naturally aspirated versions, as it would negate the advantage of the layout. [Audi has now followed suit.](http://www.eurocarnews.com/182/0/0/7684/audi-s8-520-hp-40-liter-v8-tfsi-engine-front-view/gallery-detail.html) The Audi package is in some ways even more unusual. The engine is smaller in displacement at only 4.0l, not just the turbos but even the intercoolers are packed into the V of the engine with the exhaust manifolds, and the valvetrain is at the back of the engine against the firewall. The last 2 are presumably because Audi is doing every last thing possible to move weight to the back of the engine in order to mitigate the polar moment of inertia problems associated with their AWD drivetrain. This engine should be a mechanic’s dream - On previous iterations the timing chain guides are usually gone somewhere before 100k miles and dropping the engine to replace them is a nice $7,000+ job. It sure is [fast](http://www.motortrend.com/roadtests/sedans/1302_2013_audi_s8_vs_bmw_alpina_b7/viewall.html), though. Note that both engines, despite being relatively low displacement and OHC, have fairly low redlines. The new Mustang 5.0l redlines at 7000rpm and it’s a $27k car. For now Mercedes is still stick with the more conventional V8 layout, with both turbo and NA versions, as is Porsche and everyone else. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [November 21, 2012, 1:13pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/23 "2012-11-21T13:13:32Z")
> [@Machine\_Elf](#): > > All other things being equal, engine output torque is proportional to total engine displacement. So a 5.7-liter V8 will put out about the same torque as a 5.7-liter four-banger (neglecting the difference in torque-versus-RPM curves for the two engines). > > A 5.7-liter V8 will be smoother than a 5.7-liter four-banger, owing to the greater number of (and smaller magnitude) torque pulses per engine cycle. > > Except it won’t make as much power as the high-revving V8 will. Are you not understanding that a high-revving V8 makes more power than a low-revving V8 of identical displacement? No, what I’m saying is that if a V8 made its peak power at 3000 RPM, and it was mated to a CV transmission, then it would stay at 3000 RPM as the gear ratio changes provided the acceleration. Would that be a better solution than a complicated OHC, 7000 RPM redline engine? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 1:54pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/24 "2012-11-21T13:54:22Z")
> [@Throatwarbler\_Mangrove](#): > > This is a layout commonly used on turbodiesel V8 engines that are designed from the ground up to use forced induction. There are many advantages as explained [here](http://autozine.org/technical_school/engine/Forced_Induction_4.html#Cross-bank), but I imagine in the past, using the same design on a gas engine with much higher exhaust temps would have been problematic. IMO a big part of the reason it hasn’t been done in the past is complexity/cost. It was “easier” on diesels since they don’t need a throttle thus the intake side was a little less complex than on a gas engine which would now need two separate throttle bodies. BMW and Audi can charge more for their cars so the added cost is easier for them to absorb. another reason is a lot of the V8s on this side of the atlantic are OHV and don’t have open valleys. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [November 21, 2012, 2:04pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/25 "2012-11-21T14:04:23Z")
> [@TriPolar](#): > > Don’t 8 combustions per rotation tend to provide more torque? I think I knew the answer to that once, but don’t recall. I might be thinking of something else. 4 combustions per revolution each cylinder fires once every 720 degrees. Intake + compression = 1 revolution Power + exhaust = 1 revolution. ---
**Author:** ![steronz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steronz/32/11765_2.png) [@steronz](https://boards.straightdope.com/u/steronz)\ **Post date:** [November 21, 2012, 2:11pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/26 "2012-11-21T14:11:08Z")
> [@ralph124c](#): > > No, what I’m saying is that if a V8 made its peak power at 3000 RPM, and it was mated to a CV transmission, then it would stay at 3000 RPM as the gear ratio changes provided the acceleration. Would that be a better solution than a complicated OHC, 7000 RPM redline engine? What problem are you trying to solve by capping an engine at 3000 rpms? First of all, pushrod engines can rev higher than that. The 430hp LS3 in the outgoing Corvette makes its peak horsepower at 6000 rpms, and redlines at 6600. If you want big power numbers, you’ve got to spin the thing. Secondly, in order for the 3000 rpm motor to make anywhere near the same power as the complicated OHC 7000 rpm motor, it would have to have something like double the displacement. That increases weight, size, and decreases fuel economy; not the direction automakers want to go. To wit, the 4.6L Northstar engine that you hate so much made 275hp in the 98 Deville, a 4000lb car. Cadillac’s replacement, the XTS, is also a 4000lb car, but it’s motivated by a 300hp 3.6L V6. The V6 is better in every measurable way - weight, size, fuel economy, power, and torque. That’s the direction they’re going – high revving V8s are getting replaced by higher revving V6s, not truck motors. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [November 21, 2012, 2:12pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/27 "2012-11-21T14:12:27Z")
> [@Machine\_Elf](#): > > All other things being equal, engine output torque is proportional to total engine displacement. So a 5.7-liter V8 will put out about the same torque as a 5.7-liter four-banger (neglecting the difference in torque-versus-RPM curves for the two engines). > > A 5.7-liter V8 will be smoother than a 5.7-liter four-banger, owing to the greater number of (and smaller magnitude) torque pulses per engine cycle. Yes, obviously. I have no idea where that random thought came from. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 2:28pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/28 "2012-11-21T14:28:22Z")
> [@ralph124c](#): > > No, what I’m saying is that if a V8 made its peak power at 3000 RPM, and it was mated to a CV transmission, then it would stay at 3000 RPM as the gear ratio changes provided the acceleration. Would that be a better solution than a complicated OHC, 7000 RPM redline engine? the problem with approaching it this way is that an engine’s peak power is made at wide-open-throttle (WOT.) You are practically never driving at WOT, so the actual point where a CVT will run the engine depends on the actual power demand. always remember- hp and torque ratings are at WOT. how efficient/economical the engine is at part throttle is another kettle of fish. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [November 21, 2012, 2:56pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/29 "2012-11-21T14:56:08Z")
> [@ralph124c](#): > > No, what I’m saying is that if a V8 made its peak power at 3000 RPM, and it was mated to a CV transmission, then it would stay at 3000 RPM as the gear ratio changes provided the acceleration. Would that be a better solution than a complicated OHC, 7000 RPM redline engine? It’s a fine solution - if you want to accelerate half as fast. Take that exact same CVT and hook it up to the 7000RPM engine. Same engine torque output, but since it’s spinning about twice as fast, at any given vehicle speed the CVT is providing about twice the mechanical advantage, therefore twice the torque at the wheels, therefore twice the acceleration. To sum up: if you want a whole lot of acceleration, you need a whole lot of power. If you want a whole lot of power, you need some combination of large displacement AND high revs. You can’t have just one and not the other. That’s where high-revving V8 engines are useful. ---
**Author:** ![FordTaurusSHO94](https://avatars.discourse-cdn.com/v4/letter/f/f07891/32.png) [@FordTaurusSHO94](https://boards.straightdope.com/u/FordTaurusSHO94)\ **Post date:** [November 21, 2012, 4:18pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/30 "2012-11-21T16:18:45Z")
> [@steronz](#): > > First of all, pushrod engines can rev higher than that. The current crop of NASCAR engines are a great example. They can rev 10,000+ and make something like 850hp and 450tq. ---
**Author:** ![thenonepercent](https://avatars.discourse-cdn.com/v4/letter/t/94ad74/32.png) [@thenonepercent](https://boards.straightdope.com/u/thenonepercent)\ **Post date:** [November 21, 2012, 4:23pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/31 "2012-11-21T16:23:54Z")
Only if you have a small penis. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [November 21, 2012, 8:18pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/32 "2012-11-21T20:18:03Z")
I think you are seeing the last crop of cam in block pushrods engines. With ever tightening emission and fuel economy regulations variable valve timing is becoming critical. Variable valve timing, cam profile shifting and other high tech tricks are difficult if not impossible on an OHV engine. ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [November 21, 2012, 8:18pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/33 "2012-11-21T20:18:47Z")
> [@thenonepercent](#): > > Only if you have a small penis. If it means I get to have a big muscular engine then I’ll proudly declare ownership of 1.5 inches of tumescent manflesh. 😃 No no…don’t bother checking, it’s dinky. Trust me. Nothing to see here…now gimme that big fat motor! ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [November 21, 2012, 8:29pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/34 "2012-11-21T20:29:17Z")
> [@thenonepercent](#): > > Only if you have a small penis. But the car you can take out in public. ---
**Author:** ![steronz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steronz/32/11765_2.png) [@steronz](https://boards.straightdope.com/u/steronz)\ **Post date:** [November 21, 2012, 8:30pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/35 "2012-11-21T20:30:52Z")
> [@Rick](#): > > I think you are seeing the last crop of cam in block pushrods engines. > With ever tightening emission and fuel economy regulations variable valve timing is becoming critical. > Variable valve timing, cam profile shifting and other high tech tricks are difficult if not impossible on an OHV engine. GM introduced VVT on OHV engines in 2005, so that’s not a huge roadblock. I think electronically actuated valves are going to kill camshafts altogether, though. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [November 21, 2012, 9:18pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/36 "2012-11-21T21:18:11Z")
> [@steronz](#): > > GM introduced VVT on OHV engines in 2005, so that’s not a huge roadblock. I think electronically actuated valves are going to kill camshafts altogether, though. What’s taking so long? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 9:58pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/37 "2012-11-21T21:58:55Z")
> [@TriPolar](#): > > What’s taking so long? a few things: 1. power demands. we’re already kind of stretching the limits of a “12 volt” system, and the recent arrival of electric power steering isn’t making things any easier. 1a) with the amount of power it would require to run electrically-actuated valves, the conductors will be thick (and expensive and heavy) to carry the required current 1. it’s not as simple as having a solenoid push open the valve, and let the valve spring close it. in a traditional engine, the valve is opened by the cam lobe, and past the maximum lift _the valve follows the cam lobe profile while closing and soft-contacts the seat._ simply letting the valves snap closed will cause them to break their heads off in short order. as it is right now, I wouldn’t be surprised if more than one automaker has a working system, and if so it’s likely that we won’t see it in production until efficiency/economy/emissions standards warrant the cost. > [@Rick](#): > > Rick I think you are seeing the last crop of cam in block pushrods engines. > With ever tightening emission and fuel economy regulations variable valve timing is becoming critical. > Variable valve timing, cam profile shifting and other high tech tricks are difficult if not impossible on an OHV engine. Chrysler did it on the Viper V-10 with a concentric “cam-in-cam” setup. They haven’t used it elsewhere, only on the low-volume/high-buck Viper, so I have no idea how reliable or durable it turned out to be. ---
**Author:** ![steronz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steronz/32/11765_2.png) [@steronz](https://boards.straightdope.com/u/steronz)\ **Post date:** [November 21, 2012, 10:19pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/38 "2012-11-21T22:19:30Z")
> [@TriPolar](#): > > What’s taking so long? [They’re only 14-16 months from market as of 2005!](http://www.autoweek.com/apps/pbcs.dll/article?AID=/20051014/FREE/510140701) Obligatory [wiki.](http://en.wikipedia.org/wiki/Camless) ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [November 21, 2012, 10:28pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/39 "2012-11-21T22:28:52Z")
> [@steronz](#): > > [They’re only 14-16 months from market as of 2005!](http://www.autoweek.com/apps/pbcs.dll/article?AID=/20051014/FREE/510140701) Obligatory [wiki.](http://en.wikipedia.org/wiki/Camless) nitpick with that article: _“◾Horsepower, torque and fuel economy are improved because the crankshaft’s power is driving only the wheels.”_ and the alternator, which is where the power to actuate the valves comes from. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [November 21, 2012, 10:34pm UTC](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513/40 "2012-11-21T22:34:46Z")
> [@jz78817](#): > > nitpick with that article: > > _“◾Horsepower, torque and fuel economy are improved because the crankshaft’s power is driving only the wheels.”_ > > and the alternator, which is where the power to actuate the valves comes from. Well it does take power to activate a mechanical drive train too. Electric can’t be anywhere near as efficient though. In your earlier post you make it sound like there’s actuators on each valve. I assumed there would be independent exhaust and intake trains each with a single actuator, and that it would continue to use conventional cam and spring actuated valves. What else is being done? [Previous page](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513.md?page=1) [Next page](https://boards.straightdope.com/t/are-high-revving-v-8-engines-needed-anymore/641513.md?page=3)