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You have to do the math breakdown to see if staying in X gear for another 500rpms is worth the actual power to the wheels verse shifting into the next gear.

Most of the time it's bet to run to redline to maximize the torque multiplication of that gear. But on cars that lack high end torque, it might be best to shift up in gears at the factory redline.


There are online calculators that allow you to plug in the cars gear and various torque ratings to allow you to see optimal shift RPMs. I'd look at thise before I'd risk damaging my car without any real gains./
 

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i sort of have to disagree...and i think many other knowledgable r18 owners will agree

the r18 is tuned pretty well from the factory...1.8 liter engine making more than 140hp (underrated from honda) while it is SOHC...yes it is tuned for saving gas but thats really only while it is in the econo vtec mode...other than that it is a solid engine it has more torque than the k20 and from my knowledge it is the most powerful NA SOHC 1.8 engine on the market

yes it can definitely be tuned to have more power but we wont get more power by having a higher redline unless you port and polish the head get new cams get a new intake manifold and somehow make the built in "header" flow better
lol, Si has 139 lb/ft of torque and R18 has 128 lb/ft and the R18 makes more torque?

:facepalm:

The K20 isn't designed to be a torque monster though, it's designed to be a high revving engine, and due to the nature of engine designs, you can't really get a ton of torque and a high revving motor, although anything is possible, you just don't see it much.

But ah well. It's all preference! But I still stand by the fact that the K20 makes more torque than a R18, as well as more horsepower resulting from its high revs.
 

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i will say this, a motor can only safely rev to higher rpms if the internals are built to do so. building a reliable high rpm engine takes allot of work. with the r series like most non-performance based honda motors, they are not intended to turn any higher rpm than the set red line. this is simple, why would honda build a motor for 8-10000 rpms then tune it back? in the non performance motors the stock internals are usually quite heavy and almost always un balanced. but hey if you want to blow up your stock motor go for it, i personally would wait to see if any one comes out with aftermarket pistons/rods and some valves/cams, before i rev my motor to the moon, and if these parts are never made available, then simply enjoy your bolt-ons and perhaps add a turbo kit, otherwise just enjoy your car either way, just don't expect it to perform miracles without being built properly.
 

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^so you're saying the factory 6.8k rev limit on a civic is its MAX rev limit. Exceed that by a few hundred RPM and engine damage will occur? :facepalm:

Take the Si for example. With a redline @ 8k, factory fuel cut @ 8.2k you can rev it to 8.7k on stock internals and NOT sustain damage. I'm sure it could rev higher on stock internals but THAT would be pushing it.

Again, the motor is designed to handle 9k but detuned to a nice, safe 8k redline for DURABILITY!

Same can be said about every engine produced. If manufacturers were designing motors to spin to 7k before valve to piston contact occurs, they wouldn't set the redline @ 7k because the first time you bounce off the rev limiter, the engine is toast.

I bet when Hondata releases the FlashPro for the civic, their suggested "SAFE" rev limit would exceed 7,000 rpms.
 

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^so you're saying the factory 6.8k rev limit on a civic is its MAX rev limit. Exceed that by a few hundred RPM and engine damage will occur? :facepalm:

Take the Si for example. With a redline @ 8k, factory fuel cut @ 8.2k you can rev it to 8.7k on stock internals and NOT sustain damage. I'm sure it could rev higher on stock internals but THAT would be pushing it.

Again, the motor is designed to handle 9k but detuned to a nice, safe 8k redline for DURABILITY!

Same can be said about every engine produced. If manufacturers were designing motors to spin to 7k before valve to piston contact occurs, they wouldn't set the redline @ 7k because the first time you bounce off the rev limiter, the engine is toast.


I bet when Hondata releases the FlashPro for the civic, their suggested "SAFE" rev limit would exceed 7,000 rpms.
yes the " r18" was designed to rev to the factory 6.8 not much beyond that. comparing the k series is apples to oranges as it was a motor that was designed and built with performance in mind, the r18 was not. and notice how i used words like reliability and safely. two words that go along ways to having a good reliable engine build. i suppose you might be one of those who believe that a b18b1 ls vtec swap is a simple as throwing a vtec head and all associated wiring then still hoping to turn 8-10000 rpms with it safely. :facepalm: as i said earlier, a motor hoping to turn higher rpms will only be as reliable as the internals that are used.
 

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Dude, i agree with you. All im saying is that the R18 can easily spin to 7,500rpm. How long it will do so on stock internals is another question.
yea i mean 6800-7500 isnt much of a stretch, but i would like to see what gains you could get from that increase.

but hell id try it, i mean its not often you would rev your engine that high, i'll be getting flash pro over the coming months so ill see what gains i can come up with,
 

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Im sure there will be no gain. From the Dyno's i've seen of R18, they stop making power past like 6.4ish RPM...

The members haven't mentioned anything about making power up there, just how high it can rev.

Making power is a whole other subject :thumb:
 

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Im sure there will be no gain. From the Dyno's i've seen of R18, they stop making power past like 6.4ish RPM...

The members haven't mentioned anything about making power up there, just how high it can rev.

Making power is a whole other subject :thumb:

yes but what is the point of revving that high if there aren't any gains from it lol
 

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yea i mean 6800-7500 isnt much of a stretch, but i would like to see what gains you could get from that increase.

but hell id try it, i mean its not often you would rev your engine that high, i'll be getting flash pro over the coming months so ill see what gains i can come up with,
I'm sure just like getting Flashpro for a stock Si, there will be gains throughout the whole rev range. The R18 is tuned for max efficiency, not power. Im sure maxing out the Cam angles, adding fuel to compensate for mods should yield decent gains.

Its hard squeezing power out of any N/A 4 banger, let alone an engine designed for fuel mileage.

I agree that the R18 has potential though. with an I/H/E and some nice cams, tuned properly, you should see some power improvement and STILL get good MPGs.
 

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yes but what is the point of revving that high if there aren't any gains from it lol
He engine flywheel hp might be less at higher rpms but the power to the ground might be higher in 2nd gear from 6500-7200rpms verses shifting into the lesser gear power that is in 3rd gear.

The math would need to be looked at to determine if the power is worth the wear or risk.
 

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Discussion Starter · #37 ·
lol, Si has 139 lb/ft of torque and R18 has 128 lb/ft and the R18 makes more torque?

:facepalm:

The K20 isn't designed to be a torque monster though, it's designed to be a high revving engine, and due to the nature of engine designs, you can't really get a ton of torque and a high revving motor, although anything is possible, you just don't see it much.

But ah well. It's all preference! But I still stand by the fact that the K20 makes more torque than a R18, as well as more horsepower resulting from its high revs.
ok yes but what i meant was that the r18 has more low end...the k20 is making 139 at 6k and the r18 is making 128 at 4300

thanks ryker for the links

and yes it doesnt always matter if you dont make power up really high but as long as the shift points are correct
 

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id say stick with the 6800 due to our cams

just out of experience, the r18 seems to teeter out on power at 6400 rpm. Thats my personal shift point depending on gear (for str8 line acceleration)
that last 400 rpm takes too long to accelerate for my preferences
I would be more looking to get power from adjustments to fuel trim and such
A more aggressive cam would be nice, but that wont be out until someone gets around to doing pistons and rods for the car

The r18 DOES have LESS torque, but were talking 11 ft/lbs. It has been stated before that this difference is minimal when you include weight differences. The Si (and its 6speed close ratio gear box) attempts to keep the car in its 6000-8000 rpm range. Whereas the R18 is geared for a much lower rpm. That said, depending on your racing application the R18 can contend with the Si. Until we hit straight drag racing. Where HP takes the cake. Per the full second difference from the factory between an R18 0-60 (2dr LX) and a k20 (2dr Si) [both manual]

Im a more torque loving guy. and i HATE 6 speed manuals (esp the Si and RSX type S, and celica, etc.) in regular everyday driving
With some internals, and a solid turbo, the block may handle about 400 hp before cracking. But def not at 7500 rpm. The car will make no power there due to the CAMS

besides, our gear ratio is designed for city driving. or autox depending how u look at it ;-)

stick with the stock rev limit. and do your research on fuel/air ratios.
 

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Discussion Starter · #39 ·

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there seems to be ALOT of variables not accounted for in the calculator

Crank HP vs wheel hp, crank torque vs wheel torque. Weight, size of tire, type of tire.
i dont think its giving you a really good idea about what is a good shift area.
 
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