A few motor questions (UPDATE TO OP, mod plz sticky)
- Thread starter sicbeing
- 120 comments
- 5,579 views
- 220
Azuremen
If your MR2 is a VVT-i and you haven't changed anything in the engine you have a 1.8L with 140hp.
Toyota builds the same 1.8L engine with VVTL-i that produces 192hp (Europe), 180hp (USA) This engine is mounted on a Celica TSport, Corolla TSport (European models) and the Lotus Exige.
There are some American Corollas that have this engine as well.
I have to say that I agree with Famine in this whole discussion, the 1.8L VVTL-i is a perfect example. It is a DOHC and it produces more than 10hp per 100cm3.
- 24,016
- It/It
- GTP_TheCracker
GTChamp2003Guys,what is Engine Inertia?
I searched on Google but all it did was confuse me more. I don't have the time to read all of those huge amounts of text.
I'm no expert, but i'd guess that what you are asking about is probably defined by the speed of which the engine revs ie how quickly the engine would rev between tickover and the rev limiter cutting in. A standard, cheap end of the market engine would take much longer to do this than a balanced, blueprinted race engine with lightweight internals. Most of the inertia can be accounted for by the weight of the flywheel. If you load a copy of any GranTurismo game, take a standard road car, a Vitz/Yaris for example, take it for a test on any track and just sit there, brakes on and rev it - it'll take a good second or two to go from tickover to having it bounce off the limiter. Go and install a racing flywheel on it and try the experiment again, you'll find it takes much less time to do the same thing.
- 17,865
- 509
daggoth
I have a 1987 MR2. I did the engine SWAP myself. I know what is in the car. Its a 1.6L VVT engine. It is the 4A-GE Silvertop 20Valve. It came out of a 1994 JDM Corolla.
I know what Toyota builds. The VVTL-i engine engine makes 190 HP in the Lotus Elise, and 180 HP in the Celica GT-S and Matrix XRS, and 170 HP in the Corolla XRS.
- 347
I'm interested to see how well GM does throughout time with it's passion for OHV V8s. I know right now they aren't doing too good, but that's not related to valvetrain technology I doubt.
Is the Focus really the most reliable car sold in Germany? A lot of people in America don't seem to much like the Focus, though they sell okay. I also thought the transmissions in some models of Focus weren't super reliable or maybe I am thinking of the rally car's issues...
Ford's reliability issues in the '90s had nothing to do with the OHV motors. The 302 (5.0L) is still currently hands down more reliable than a 4.6L for example. Ford's problems in the '90s were very different with each car from what I understand--things like headgaskets on the 3.8L, cruise control switches, alternators, etc... Nothing to do with the motors themselves let alone OHV technology. The 4.6L has improved very drastically within the last 6 years though.
Is the Focus really the most reliable car sold in Germany? A lot of people in America don't seem to much like the Focus, though they sell okay. I also thought the transmissions in some models of Focus weren't super reliable or maybe I am thinking of the rally car's issues...
Ford's reliability issues in the '90s had nothing to do with the OHV motors. The 302 (5.0L) is still currently hands down more reliable than a 4.6L for example. Ford's problems in the '90s were very different with each car from what I understand--things like headgaskets on the 3.8L, cruise control switches, alternators, etc... Nothing to do with the motors themselves let alone OHV technology. The 4.6L has improved very drastically within the last 6 years though.
- 17,865
- 509
daggothokay okay
You wrote that you did no alteration to the engine, so I assumed it was a new stock MR2!
I meant no offense
And that engine gives 192hp in Europe! It's only mounted in the Corolla TSport and Celica Tsport?
Why the difference in hp? Anyone care to explain?
The engine is the 2ZZ-GE that you are refering to. The one found the MR2 Spyder is the 1ZZ-FE.
The 2ZZ-GE found in teh Lotus Elise was tweaked with a bit to produce additional power and torque, though I think at the cost of engine life a bit.
The version in the Corolla GT-S is setup, in the US at least, for 180 HP. The Corolla XRS is setup to have a little more low end torque, as its still a Corolla. The result is less torque at high RPM, and thus a little less peak HP. Also, I think Toyota did not want to do out do their Celica GT-S by making a Corolla with the same power output in the US.
We don't have TSport models here, so I imagine that is just your sports badging there. GT-S and XRS are Toyota's US sports badges.
- 120
Hi,
I'm a relatively new member, but I thought I'd offer a bit of knowledge on the OHV v OHC debate. Although this thread has meandered a touch to different subjects, the core discussion appears to be which is best.
I work for an automotive OEM and which is the best layout depends on a huge number of things.
The reason a lot of US OEM's use OHV, still, is probably due to a mixture of cost (why would you spend a few hundred grand on a single new HP diecasting tool just to have OHC?), familiarity with the design and concept, experience in designing the pushrod system, and market and brand awareness. And to be fair, although I'm a brit, I still love the noise of a big OHV US V8.
If however, you were limited as a designer to a specific engine configuration and size, for racing homologation for example, unless you HAD to work modifying an old engine to save costs, you'd go for DOHC. You get a much better included valve angle from OHC's in general (it's possible to get a 25 degree on OHV, but the packaging is a nightmare.) and much better volumetric efficiency due to the greater valve area. This is assuming an OHV with a 2 valve head, although they don't have to be, but packaging is a nightmare again.
If you were going for all out power, you'd go for DOHC. Again, assuming a max capacity. Better volumetric efficiency will give you a better torque output.
Thermal efficiency will be affected by the valve train to an extent, but it is more heavily affected by the quality and homogeneity of the fuel mixture, compression ratio, and the valve and spark timing. Thermal efficiency relates the amount of useful energy (kinetic) derived from your fuel's chemical energy. Typically about 35% for unleaded, 40% for diesel. No commercial IC engine in the world can get much past about 50%. Even then it's a marine two stroke diesel, a million foot pounds at about 102 rpm, nice, just what you want in your race rocket...
There is a huge amount of variables to take into account, and I can't cover them all, because I don't know them all. All I can say from my perspective is that every new engine we've designed in the past 10 years has been DOHC. Whether it's been for a sports orientation, or cruising, workhorse, whatever, they are all DOHC. For us it would be a marketing mess to have the word "pushrod" in a press pack, but for a 'vette or mustang it's probably the other way round.
thanks for reading, and if I'm wrong, let me know, I'm always trying to learn.
Kurtis.
I'm a relatively new member, but I thought I'd offer a bit of knowledge on the OHV v OHC debate. Although this thread has meandered a touch to different subjects, the core discussion appears to be which is best.
I work for an automotive OEM and which is the best layout depends on a huge number of things.
The reason a lot of US OEM's use OHV, still, is probably due to a mixture of cost (why would you spend a few hundred grand on a single new HP diecasting tool just to have OHC?), familiarity with the design and concept, experience in designing the pushrod system, and market and brand awareness. And to be fair, although I'm a brit, I still love the noise of a big OHV US V8.
If however, you were limited as a designer to a specific engine configuration and size, for racing homologation for example, unless you HAD to work modifying an old engine to save costs, you'd go for DOHC. You get a much better included valve angle from OHC's in general (it's possible to get a 25 degree on OHV, but the packaging is a nightmare.) and much better volumetric efficiency due to the greater valve area. This is assuming an OHV with a 2 valve head, although they don't have to be, but packaging is a nightmare again.
If you were going for all out power, you'd go for DOHC. Again, assuming a max capacity. Better volumetric efficiency will give you a better torque output.
Thermal efficiency will be affected by the valve train to an extent, but it is more heavily affected by the quality and homogeneity of the fuel mixture, compression ratio, and the valve and spark timing. Thermal efficiency relates the amount of useful energy (kinetic) derived from your fuel's chemical energy. Typically about 35% for unleaded, 40% for diesel. No commercial IC engine in the world can get much past about 50%. Even then it's a marine two stroke diesel, a million foot pounds at about 102 rpm, nice, just what you want in your race rocket...
There is a huge amount of variables to take into account, and I can't cover them all, because I don't know them all. All I can say from my perspective is that every new engine we've designed in the past 10 years has been DOHC. Whether it's been for a sports orientation, or cruising, workhorse, whatever, they are all DOHC. For us it would be a marketing mess to have the word "pushrod" in a press pack, but for a 'vette or mustang it's probably the other way round.
thanks for reading, and if I'm wrong, let me know, I'm always trying to learn.
Kurtis.
- 120
Thanks!
I'm glad to be here and I'm glad I found the place!
Kurtis
I'm glad to be here and I'm glad I found the place!
Kurtis
- 3,534
- London
I have a question:
Ive noticed this a lot in GT4. Why does the power drop off so significantly when an engine revs past a certain amount? I know what will happen if it goes past the redline but i dont know why the power drops off so suddenly.
Heres a picture to try and explain what i mean:
Also, do you think this thread should get a sticky so you dont have to start a new thread to ask a question but post it here??
Thanks.
Ive noticed this a lot in GT4. Why does the power drop off so significantly when an engine revs past a certain amount? I know what will happen if it goes past the redline but i dont know why the power drops off so suddenly.
Heres a picture to try and explain what i mean:
Also, do you think this thread should get a sticky so you dont have to start a new thread to ask a question but post it here??
Thanks.
- 120
An engine's power output is a balance of internal friction against it's power production.
Any engine, even the best has a huge amount of internal friction. The pistons, rings, bearings and pumps all feed off the engine power. When an engine is running in it's desirable speed range it easily overcomes it and produces buckets of grunt for us to play with.
As an engine revs higher, the mass of the pistons, rods and valve train all needs accelerating faster, requiring more power. There will come a point where due to valve timing, fuelling, many other reasons and the overall engine architecture, the amount of power required to turn the engine increases at a faster rate than the "theoretical" power output does. This means the power drops off. And it does it at an exponential(ish) rate, dropping faster the higher you rev it.
The rev limit can be raised by reducing the engine's oscillating and rotating mass, or reducing the stroke and increasing the bore. The reduction in stroke reduces the acceleration of the pistons and valves, using less engine power.
Kurtis.
Any engine, even the best has a huge amount of internal friction. The pistons, rings, bearings and pumps all feed off the engine power. When an engine is running in it's desirable speed range it easily overcomes it and produces buckets of grunt for us to play with.
As an engine revs higher, the mass of the pistons, rods and valve train all needs accelerating faster, requiring more power. There will come a point where due to valve timing, fuelling, many other reasons and the overall engine architecture, the amount of power required to turn the engine increases at a faster rate than the "theoretical" power output does. This means the power drops off. And it does it at an exponential(ish) rate, dropping faster the higher you rev it.
The rev limit can be raised by reducing the engine's oscillating and rotating mass, or reducing the stroke and increasing the bore. The reduction in stroke reduces the acceleration of the pistons and valves, using less engine power.
Kurtis.
- 3,534
- London
KurtisGSXR
Thanks a lot. Great explanation!! I was worried when know one answered, i thought my question may have not made any sense!
Anyway, I thought it had something to do with then weight of the pistons more than the friction...
Your explanation has got me thinking, there must be sooo much pressure on the engine's components when revving high.
- 1,397
in addition to what teh esteemed gentlemen have already said, they can makes the cars rev higer and higher and higher to make more power.
but that has to be weighted against cost. would you like a $100000 honda civic? didnt think so.
race cars use fancy and very expensive parts and car rev into the teens. thats why you see so many racing bodies have rules for regulating everything. exotic makes horsepower. exotic costs money.
but that has to be weighted against cost. would you like a $100000 honda civic? didnt think so.
race cars use fancy and very expensive parts and car rev into the teens. thats why you see so many racing bodies have rules for regulating everything. exotic makes horsepower. exotic costs money.
neanderthal
You don't need more power when it comes to driving cars on the road. Torque increases drivability, not power. Power is just basically a 'big head' value.
Plus whats the point of having cars eventually revving to 50,000 rpm?
decibel rating, anyone?
👍
On the whole cam thing, I reckon pushrods should stay. Nice and simple design. Technology isn't everything IMHO. Hell, in Australia, the 'top' car manufacturer, Holden - their v8s are all complete pushrod engines. Even car magazines praise them that they are still making 30-40 year-old technology work.
=]
- 120
Slick Rick
The reciprocating mass does contribute a lot. But it is a dual edged sword. A lot of motorcycles are coming out with heavier cranks, when typically year on year they were becoming lighter. this is to improve drivability. A low inertia engine has a fast, agressive throttle response making the bike difficult to ride. I would think the property would be much reduced in cars due to the inertia of the flywheel and drive train.
Although it varies greatly from engine to engine, a typical spark ignition engine can have a peak cylinder pressure of 40-70 atmospheres, which is up to over 1000psi. Diesel engines are higher still. The highest pressures in an engine nowadays are not in the cylinder though. Modern diesel engines have fuel pressures of up to 20,000psi.
And I would agree power isn't everything, I like torque. Specifically low range torque. This is because I'm a lazy driver and I drive slowly. My bike is for riding fast, I don't want to have to work hard in my car too! So personally I'd go for an auto box and a nice quite ride. With a seat which gently cradles me like a lover...
Ahem...
Excuse me.
- 5,178
- Worcester, MA
- skip0110
Heh. I had one of those.DukeIf he has an AWD Civic, it's probably the RealTime AWD Civic Wagon from the late '80s/early '90s. It only put 15% of the power to the rear wheels, so it was hardly worth the effort, but hey.
There was a member here named 12secCivic who had installed that running gear into a turbocharged Civic hatch; it wasn't all that fast considering, but it was a cool idea.
Just to nitpick, the '85 had a part time system with 50/50 split...but the later Real-Time system was indeed front biased.
- 3,534
- London
sicbeing
i think you should ask a mod to make this thread a sticky because its a good thread to ask general questions on cars.
- 24,016
- It/It
- GTP_TheCracker
sicbeing
1. Your best off asking an expert on what ever engine you are thinking of - i doubt anyone here can give you a complete answer.
2. The larger the engine size, the larger the cylinder capacity, the larger the capacity, the bigger the bang, the bigger the bang, the more power you get - a bit simplistic, but basically true.
3. I think Duke has already answered this in one of the posts you quoted him on. Its basically a shaft of rotating steel with lumps that raises and lowers the valves, controling the input of fuel and air and expelling the spent gases (exhaust). Overhead cams sit over the engine's head. Others usually sit below the head and operate the valves via 'push-rods'.
These are very basic discriptions!
- 1,103
- Cribanox
xcsti
yea, true, i just kinda hate when there is a sticky/etc that was made from pages up pages of people talking back and fourth and the reader has to wade through all the posts when all they want is the info.. so at least I tried to help
I can remove it if enough ppl think i should
- 2,415
sicbeingyea, true, i just kinda hate when there is a sticky/etc that was made from pages up pages of people talking back and fourth and the reader has to wade through all the posts when all they want is the info.. so at least I tried to help
I can remove it if enough ppl think i should
I don't think you need to remove it, I was just making a point.
- 220
Whoa! I'm up there on the first page? 
That's cool, thanks sicbeing 
I know now the name of the part: It's the flywheel !!! lol So when the clutch disk is compressed to the flywheel you link the engine with the transmission. If you want to change to the correct name in the post go ahead
And I don't think you should delete the stuff on the first page, there is a lot of good info there.
That's cool, thanks sicbeing I know now the name of the part: It's the flywheel !!! lol So when the clutch disk is compressed to the flywheel you link the engine with the transmission. If you want to change to the correct name in the post go ahead
And I don't think you should delete the stuff on the first page, there is a lot of good info there.
