why obsess over rev limits?
 

why do people care so much about this? i mean i understand that nobody wants a diesel in this thing but when i see comments like "if it doesnt have a redline of 8xxx im not buying this." ill admit that it is kind of a neat novelty but a if a higher redline doesnt mean more power, what is the big deal?

I could care less about high redline 4 cylinder engines as they make shitty ass torque(IMHO) in the range that matters to a daily driver 2k-4.5k rpms. The only time I will care for a high revving engine is when it has 6 or more cylinders.

Power is torque x rpm, so a higher redline DEFINETLY means more power..
And having a higher redline means you have more revs to play with ;)

I don't get it either. At first I thought they were troll posts, but I began to see them more and more. I couldn't tell you what my Miata redlines at, and I don't care. Fun is definitely not RPM dependent.

Divided by 5252. If your torque falls off enough, you're not going to make any more power no matter how high its redline may be.

More rpm doesn't necessarily mean more power, but if the rev limit is higher that suggests there is more power since the manufacturer wouldn't give you more revs if the power dropped off. Of course this is design specific, if the engine has higher specific torque then a lower rev limit doesn't necessarily mean less power, but the specific torque of engines with the same displacement is about the same.

At the end of the day, everything people are asking for is MORE POWER. lol.

More revs mean you can use gearing to better take advantage if the limited torque available from a small NA engine. Plus high revs can be fun to drive. I'd prefer shorter gearing and higher revs myself.

:bow: ding ding ding, its not about makeing hp its more trying to maintain trq band, when you shift gear rpm drops but if you can shift on a higher rpm you can stay on a higher trq band.

it depends on your tq curve. if your tq is going down, and you increase the rev range, you can get to the point where the next higher gear will actually make more tq at the wheels. granted this is more prevalent on large displacement V8's where peak tq is down low, but the point remains...

it never ceases to amaze me some of the stuff that's posted here. test drive an ap1, then compare it to your miata. it's a personal preference, but when you drive the ap1 hard(9000 rpm redline) it should be quite obvious why so many people like high revving engines.

I'm used to the power coming on above 8K and redlining at 14K! :popcorn: ;) That high reving whine is music to my ears!

As I mentioned before, I'm going to assume this car will redline but @ 8k but peak out around 7,700. Who doesn't like a rev happy engine!

I like high revs... Can change gears and get moving faster than if the rev limit was at 4k. :x

I like it also comes in handy when you're on the high way and you're coming off from a circular on ramp with a stupid stop light and cars merging into your lane. :x

A sports car is about power on high rev and not about torque. It is about not about power or torque but HOW power and torque are delivered. Power should be linear till redline and the torque curve should be as flat as possible. You think you get a flat torque curve with a turbo? Maybe in low range, but upper there is nothing left, and at the beginning there is also nothing unti lthere is no boost. Just look at these two different engines. The N54 is a turbo engine, with alot of torque in the mid range, but nothing around. The S54 is a naturally aspirated engine, has less torque but a completely flat torque curve. The power delivery is linear, mcuh better to drive in a sporty way.

Higher revs means more area to play with in one gear, and even if it drops off you can keep accelerating without shifting which is very important when you have a corner coming up. Dont want to go 3>4>5 for a sec then 5>4>3. Much rather hit the limiter in 4th or keep accelerating if you have a high revving car.

everyone has already said everything that needs to be said

for the guys that complain about lack of tq and high revs from a small displacement engine really need to go and drive a s2k (ap1 FTW) the amount of enjoyment you will have will change your mind

besides I love the scream you get from the car when your are climbing to the redline

this is true to a point. it is 1000% application specific. for a streetcar i'd say NA or roots SC is the way to go. auto x also favors NA. but if you're talking about racing, turbo engines rule.

thats more an issue of gearing

ill give you the sound but if you had the same power curves those numbers dont do anything. ps i love the s2k but its kind of a stupid motor

Im one of thous guys who gets is but cant explain it (it bits) and the best way I can say it when youre coming offf the line who ever shifts first get more acc in the next but you loose to the higher rev motor because there still acc while your shifting gear.

Call me out and all I can say is what I said at the begining..

I knew some one was going to bring that up haha!
I love that show!

but it can affect the engine or not? I think this is kind of risky.

What is?

I'd RUN to the dealership if they were offering this car in a sporting bi-turbo Diesel model. 168 HP & 258 LbFt [like the one from the VW Transporter in EU] would be a ball of fun. Not to mention the CBBB sounds fantastic and gets incredible fuel economy.

Rev's are fun, but only if the engine sounds good. What's more important is the overall character is free-revving and fun. There are many engines that are both without having a high redline.

I too get excited over performance diesels... How about the 145hp/255tq 2.0D in the forester? If they performance tuned that thing it would be a hoot to drive, regardless of whats happening on the tach.

One article mentioned the ND Miata trying out the Skyactiv-D engine. I about creamed myself, great mileage and torque would be awesome fun.

Engines only make torque, rev limit is how you modify the torque that it makes to suit the application... It is useless for a truck to have high hp without torque because it won't do the job when you stuff it with weight, the opposite can be true for a sports car that is designed to hold driver plus maybe one extra person and minimal luggage to have more torque than needed obstructing it to do more "work" (hp)... High reving an engine is the best way to convert raw torque to hp, you gain one or the other usually by doing a couple of things, like increasing/decreasing bore and stroke... Of course having more bore means more momentum, however, more weight means more inertia and less revs... Same with longer stroke means more leverage, but longer stroke means more travel / stroke = less reps = revs...

If given the same motor, high revs will usually mean higher hp thus winning a race at the high end because your car is doing more "work..." However, if the race is up a very steep hill, and the potential of the hp is never realized, then the motor with the higher torque reaching a higher hp will win because the lower torque vehicle can never overcome the inertia it needs to generate the max hp it has... THIS is the reason why auto makers lower revs is because we need to drive it everyday...

I'm no expert, but tis what I know... Or what I claim to understand to know...

Compression is also another thing that comes to mind, but naturally a low reving engine will last longer than a high reving one... Also, if you ever plan on having FI added to your vehicle, it'll "probably" be easier with a low rev motor than a high one, high rev is best suited for N/A motors tricked out to the max... Once again, I might have to eat crow, but tis what I think I know...

I think the real reason trucks have a lot of torque is because they have very heavy loads, and fuel economy is extremely important. Hence trucks use diesel engines, which due to higher compression ratio, turbocharging, and greater specific energy in the fuel, have higher specific torque.

If you ever watch a big rig accelerate though, it is PATHETIC. The engines have huge displacement, but for what they're pulling, not really lol. If diesel engines could rev higher, trust me, they would do that. Diesel is there for the fuel efficiency, it actually has rather low specific power which isn't a good thing. You could theoretically have a gasoline powered truck that was just as good, but it's so much easier to use a diesel for large power and low fuel cost.

The main problem with the high rev engines we've seen in the past is actually gearing, IMO. What people are seeing is these low displacement motors need to rev higher for power, and give basically the same result as a higher displacement motor which doesn't rev high and is cheaper. But guys, think about the one advantage a lower displacement has for a car...fuel economy! Cars like the S2K almost don't even use this advantage because they are geared so short. So we see decent city economy, but highway is completely pathetic for an engine that small. In the future I think people will appreciate high revving motors more, as companies turn to tap this easy fuel economy gain. I know most S2K owners probably don't complain about the fuel economy, but imagine if it were almost as good as a Civic. Plus I think people would appreciate if their engine wasn't screaming at 4000 rpm every time they had to go on a longer trip on the highway.

Diesel is actually more expensive at most pumps now than even 91 octane...

As for trucks, I wasn't going the end of the rainbow on spectrum for semi-trucks, but full size pickups... (Lightning, X-Runner, all the V8 big boy trucks, etc...) They're truck first performance 2nd because they need torque to even reach the hp they're capable of... Without it they'll be bogging...

The one exception to the rule would be the Ram SRT-10 which just threw a Viper engine in a truck... That thing was never a truck, and it was never a sports car... It was just horrible... If you wanted to go fast, the Viper is faster, if you wanted to buy something huge, then a regular Ram is better...

I don't think I can recall a car with a truck motor in it tho lol =P

I got around 29MPG on the highway with the S2K. Not great for sure, but not horrible. (that was some of the best though, probably 28 was more average)

In my ITR I rev higher on the highway than I did with the S2K and it shows about 4500rpm on the highway (@80) vs 4250.. I get mid 30s easily with the ITR.

...good enough to be the winning formula at 24 Heures du Mans since 2006. :)

I suppose it depends. I'm planning on raising the limiter on my car from 6k to 8k for this reason.

Stop choking the gas motors for 'parity' and see what happens. :)

Bring back the 4 rotor wankel for Mazda while you're at it

I believe the Viper engine was base off a truck engine

and the KA24DE can be found in both cars and trucks

Easily one of the best FWD cars out there

For MY2009, the MX5's redline was extended from 6700 to 7200 (without increasing peak power, and with only marginal changes to the torque curve). 6th gear was made a tad taller, but otherwise gearing was left the same.

This provides extra flexibility as blur mentioned. It also means dramatically more wheel torque for MPH corresponding to 6700-7200 RPM (since you're in a lower gear) and means higher RPMs after each up-shift compared to MY2008 (so you stay closer to peak power).

Alternatively, they could've made the overall gearing 7% shorter (so that redline in each gear came at the same MPH as with the previous motor). This would've resulted in approximately 7% more wheel torque almost everywhere (not exactly 7% since the torque curve isn't identical between the two engines).

However, using shorter gearing would mean a decrease in MPG. Also, some don't like to rev and have a "drive below 4k RPM" approach. With shorter gearing, if you upshift at the same RPM (as with the engine with taller gearing), you'll be in a higher gear at lower vehicle speeds after each upshift (resulting in significantly less wheel torque at said vehicle speeds).

i understand that examples with that kind of specificity woere are people but there are people saying they wont buy the car unless it revs to xxxxrpms without having seen a single spec.

the best example i can think of is the EM1 Si's compared to the EP3 Si's. the EM1 revs to 8000 or so, the EP3 revs to 7000 or so. the EM1 is considerably more fun to drive (IMO) than the EP3, and that is due in large part to the high revs. it's really stinking fun to rev the snot out of the EM1.

Another is the s2k ap1 and ap2 . . . ap1 hitting 9k rpm, ap2 8k rpm.

I don't understand what you mean in the first half of your post, but it was announced to have a 2.0L N/A piston engine (H4) a long time ago.

yeah that was my phones fault. my point was that there is this hang up one one factor that doesnt make or break a sports car.

i also dont know if i agree on the civic and s2k examples as i wouldnt say its the rev limit that killed the ep3 and i dont know if the ap1 is better than the ap2

I haven't seen any posts claiming redline is the one factor that will make or break a sports car. But given that the FT has only a N/A 2.0, more RPMs will help (for the various reasons already discussed).