single overhead

 

to be more specific, we have a single overhead cam and 24 valves. Most engines need 4 cams to run 24 valves, but ours is special and only uses one cam per head (2 per engine).

 

SOHC with 2 cams One for each bank of cylinders.

 

to be more specific, we have a single overhead cam and 24 valves. Most engines need 4 cams to run 24 valves, but ours is special and only uses one cam per head (2 per engine).

Doesnt the cam have to work harder being that it has more lobes than a DOHC setup? I guess I always thought that having DOHC over SOHC the more the cams, the better the efficiency and less stress on the cam to begin with. Anyone else know anything about this?

 

Ive been wondering stuff like that also. I see some cars say OHC and some say SOHC. whats the difference?

 

OHC is a step up over OHV *overhead valve, or pushrods* so they like to point that out. Kinda like "look, we're modern and don't have to use pushrods anymore!" but in reality, no self-respecting Japanese company would ever put that. They always say SOHC (not proud of it) or DOHC (a little better). Yeah, and only Toyota really says "quad cam" cuz they really like to point that out, although Nissan and Honda DOHC V6s are "quad cam" as well.

But yeah, OHC and SOHC are the same.

 

well one car from Japan (that im certain of) has OHC and thats the 240-280 Z with the L24-6-8 engine and im sure any car using the L-series engine would havr OHC on the valve cover. like the datsun 510 and so on.

 

Well, depends on the type of car. For luxury and slightly lower cost (since less cams), it seems that SOHC is sufficient. But this is at the cost of higher performance - since its hard for one cam controlling intake and exhaust (via rocker arms) to give economy and performance. You can get a more aggressive cam in a SOHC, which will almost give as much performance as DOHC, but it will not be as efficient, especially at lower end. Hence the whole reason for DOHC and VTEC i suppose.

Here's a good resource, especially on the history of multi-valve:

http://autozine.kyul.net/technical_school/tech_index.htm

 

The L-series motors in the old Zs were still SOHC. Around that time however, no one ever imagined such a thing as TWO overhead cams, so why would they specify OHC as having only one single cam? The acronmym SOHC only came about after twin cams were around to differentiate it.

 

The L-series motors in the old Zs were still SOHC. Around that time however, no one ever imagined such a thing as TWO overhead cams, so why would they specify OHC as having only one single cam? The acronmym SOHC only came about after twin cams were around to differentiate it.

true

OHC was the "wave of the future" then how far we have come...

btw in your signature, what is it about Forced induction do you not like? you say cheap but what about it is cheap?

 

btw in your signature, what is it about Forced induction do you not like? you say cheap but what about it is cheap?

From my understanding, it takes alot more R&D and engineering to derive the greatest amounts of HP/cc out of a N/A engine than it does to slap a turbo onto a basic engine that has just been built with stronger materials and crank the boost up.

It is cheaper.

Try taking our engine and get 400hp out of it both N/A and F/I. Turbocharging it would be cheaper.

G

 

That's exactly it. While Mercedes uses superchargers and Audi uses turbos, BMW remains true to natural aspiration. Mercedes and Audi (as well as many other commpanies) often rely on forced induction to power their highest performing machines ~ but BMW still remains competitive with their naturally aspirated motors.

Think about that: while it's easy to slap on a turbo and get big power, BMW instead dives into further engineering, tweaking their engines for all they've got, applying new technology and engineering each detail to its fullest. Double VANOS, Valvetronic, etc. are all results. Every little thing has to be designed to fully extract the potential of the motor. With forced induction; you can have a ****ty design and still make that kind of power. You can have flaws and mistakes and offset it with a supercharger, or hide your engineering downfalls with a turbo. BMW still stands strong with natural aspiration... doing it right... the hard way.

Turbo is great, but there are plenty of downfalls. Power delivery is uneven, intercoolers and extra piping is heavy and bothersome, extra oil lines and fuel-mapping is annoying, and throttle response and control overall are lost.

Superchargers are much the same way... powerbands in supercharged cars are notoriously peaky, the throttle response suffers also, and like a turbo, full control of the car is lost. With forced induction, you hand over control over power to weather conditions, ie humidity and ambient temperature.

Although such factors play into naturally aspirated performance as well, think of how much more an n/a engine is "free" of outside conditions since it doesn't have to deal with lower compression, intercoolers, uneven boost, or differing air pressures.

Man I can go on and on ~ but just put it this way: when you pull on a car that's blowing off, when you overtake a car with the telltale supercharger whine, when you pass up a turboed whatever, and you are still naturally aspirated, then what does that say about how your car is built? It's the respect.

 

My 86 Maxima has OHC on the engine. It's the same engine as the 300zx back in the day.

 

Yeah the VG30E. It later became the VG30DE (DOHC).

 

ahhh makes cents

 

That's exactly it. While Mercedes uses superchargers and Audi uses turbos, BMW remains true to natural aspiration. Mercedes and Audi (as well as many other commpanies) often rely on forced induction to power their highest performing machines ~ but BMW still remains competitive with their naturally aspirated motors.

Think about that: while it's easy to slap on a turbo and get big power, BMW instead dives into further engineering, tweaking their engines for all they've got, applying new technology and engineering each detail to its fullest. Double VANOS, Valvetronic, etc. are all results. Every little thing has to be designed to fully extract the potential of the motor. With forced induction; you can have a ****ty design and still make that kind of power. You can have flaws and mistakes and offset it with a supercharger, or hide your engineering downfalls with a turbo. BMW still stands strong with natural aspiration... doing it right... the hard way.

Turbo is great, but there are plenty of downfalls. Power delivery is uneven, intercoolers and extra piping is heavy and bothersome, extra oil lines and fuel-mapping is annoying, and throttle response and control overall are lost.

Superchargers are much the same way... powerbands in supercharged cars are notoriously peaky, the throttle response suffers also, and like a turbo, full control of the car is lost. With forced induction, you hand over control over power to weather conditions, ie humidity and ambient temperature.

Although such factors play into naturally aspirated performance as well, think of how much more an n/a engine is "free" of outside conditions since it doesn't have to deal with lower compression, intercoolers, uneven boost, or differing air pressures.

Man I can go on and on ~ but just put it this way: when you pull on a car that's blowing off, when you overtake a car with the telltale supercharger whine, when you pass up a turboed whatever, and you are still naturally aspirated, then what does that say about how your car is built? It's the respect.

So, what your saying is, you admire Honda more for not going F/I?? Honda does have the highest specific output motors for the money, am I right???
Most VTEC Hondas are at 80-120 HP/Liter. Only BMW M technology can match Honda for bragging rights, and of course torque also. But, generally, Honda has more high specific output cars available ( or did thru the 90's) than BMW, at a MUCH cheaper cost.

Anyway, most people don't care about how the power is made (Camaro and Mustang peeps), they just know they want it. I don't think F/I is cheating. Spending a but-tload of money on engineering a expensive motor is cheating us out of affordable fun.

 

i always thought our car was dohc...guess not

 

So, what your saying is, you admire Honda more for not going F/I?? Honda does have the highest specific output motors for the money, am I right???
Most VTEC Hondas are at 80-120 HP/Liter. Only BMW M technology can match Honda for bragging rights, and of course torque also. But, generally, Honda has more high specific output cars available ( or did thru the 90's) than BMW, at a MUCH cheaper cost.

Yes, I do admire Honda for that. I am a great Nissan fan, but I do hold respect for Honda simply because of their pig-headedness about the n/a issue. Hondas make big specific output per liter. I think BMW actually has one up on Honda though, because BMWs make torque, whereas Hondas mess with hp/torque ratios for marketing purposes. Remember, horsepower sells cars, but torque is true power. :werd: So my friend can say: oh yeah?!! well Preludes have 200hp just like your Legend!!! And I can say, yeah really? but does the H22 make 210 lb/ft of torque? Alright, shut up then.

Anyway, most people don't care about how the power is made (Camaro and Mustang peeps), they just know they want it. I don't think F/I is cheating. Spending a but-tload of money on engineering a expensive motor is cheating us out of affordable fun.

That's not always true. Viper and big block muscle-car drivers eventually complain about their sorry gas mileage, and every Honda owner is a spokesperson for specific output. "oh yeah?!! hondas 120hp out of 1.6L!!!" Man I hear it all the time. Some people do care how their power is made... at least the car enthusiasts do.

BUT most of all... it's not about how the power is made, but how it is delivered. Some people like that turbo kick around 3000rpm. Some people like that progressively louder and louder whine as supercharger boost builds up. Some people like to press a button that sez "NOS" and feel that surge of speed. But race car drivers? Autocrossers? Professional drivers? They appreciate the control that comes from natural aspiration. No forced induction can give the straightforward power delivery of an n/a motor. The throttle DIRECTLY controls engine speed. No spool up, no power peakoff, no nothing. Just you and the engine as one. See... while some people like to have power over 3000rpm (turbo) or have power build up beneath the pedal over time (supercharger), I happen to want my power to be there ALL THE TIME, on call when I want it, whenever I need it. That's throttle response. Natural aspiration anybody?

 

I love machines. That is why I love Hondas, they are the best engineered machines. They combine sensible engineering with great design (or they did). The PGM-FI system was so simple compared to GM, Ford, BMW, Mopar FI systems. But, it turned out to be the most reliable EFI system ever made. All the other EFI system engineers were so busy patting themselves on the back for writing complicated routines and codes and integrating the freaking power windows and turn signals into the body computer and complicating everyone's lives. Honda kept it simple.

BTW, on your muscle car arguement, I KNOW a Camaro Z28 gets better gas mileage than a Legend. I had a Camaro Z28 (92) and it got 40% better MPG than my new at the time 97.5 Altima SE.

 

BMW, Ferrari and Honda make the best N/A.
Nissan makes the best Turbo and Autos.
And Toyota is the best reliability and integrity.

 

BTW, on your muscle car arguement, I KNOW a Camaro Z28 gets better gas mileage than a Legend. I had a Camaro Z28 (92) and it got 40% better MPG than my new at the time 97.5 Altima SE.

Oh sure I believe that. Even a Corvette can be more frugal than a second-gen KA. But I was referring more to my grandpa's Chevy Nova with a 350 small block, or those '67 Mustang hotrodders.

 

BMW, Ferrari and Honda make the best N/A.
Nissan makes the best Turbo and Autos.
And Toyota is the best reliability and integrity.

I think BMW makes the best n/a. Honda is good, but they are more playing the numbers game by sacrificing torque (high-revving motors) in exchange for a good horsepower figure. BMW does a "true" power increase. And Ferrari... well they're exotics. What do you think?

Mazda makes killer n/a too. Ever seen their Miller cycle engines? And what about the rotary? Sure it's known for being turbo, but the revised 13B (RENESIS) makes 250hp too... and that's WITHOUT a turbo. *but take note... it has no torque. You need displacement for that*

Nissan has killer turbos, Mazda too. Autos though...? Ahh I look to Mercedes-Benz for smooth-slushboxes.

I can agree with you for that reliable Toyota thing though.

 

Mazda makes killer n/a too. Ever seen their Miller cycle engines?

I thought Mazda's Miller Cycle was only applied to the Millenia S, which happens to employ a light pressure S/C.

 

Sorry I just checked. You're right ~ miller cycles are dependent on superchargers. I stand corrected on that. I'm right about that RENESIS rotary though.

 

Yeah, I think Mazda only had Miller Cycle technology in the Millenia S.

It is very interesting for sure.