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Old 10-07-2010, 12:48 AM   #1 (permalink)
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Methods for on-ramp acceleration uphill?

I try to get up to or near the 70mph speed limit to merge and have to get onto aa short and steep onramp. My cas is a 98 Acura Integra with 5 speed MT and vtec motor with 8100rpm redline.

Currently I just give it very light throttle and rev up to 4k instead of 3k like usual. Would it be better to use the vtec which kicks in at 4400 rpm?

What is best for mpg and what is best for minimizing wear and tear? A good compromise?

I've only had. The car two weeks and the final drive is 4.440 managed 34mpg highway still. I am waiting on an ultra gauge and have a vacuum and a/f gauge to install also.

Somewhat related assuming the knock sensor is functioning would it hurt to run regular or midgrade? I'll pay he extra to prolong car life but feel it may be a waste the way I drive which is very mild. I'm sure it's fine unless I need to accelerate in an emergency but the knock sensor should compensate in theorrry. The non vtec version with 140hp instead of 170 runs on regular I think.

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Old 10-07-2010, 01:28 AM   #2 (permalink)
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Find a BSFC chart for your engine (none posted yet), and look for the RPM band that gives you the least fuel consumption at max load. This is usually 2000-3000 RPM, but varies based on engine design. If you have a vacuum gauge, keep it at 2-5 in. Hg, almost floored but not into the acceleration enrichment.

Better yet, get a scangauge or mpguino! Then you'll see for yourself.
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Old 10-07-2010, 01:37 AM   #3 (permalink)
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I don't really know why a car needs a knock sensor anyway, you can tell it is knocking well before it becomes hazardous if you have the radio turned down to a normal level. That being said I would suggest running what the car calls for, if you feel like running lower grade fuel it may be economical if you are not loading engine fully as you drive now..

As for accelerating up hill to merge, those Honda motors love to rev when they need to make power, going 3/4 the way to redline if needed for short bursts (assuming it is up to temp and the oil is flowing well) will do no damage. If you can do it in 5th gear press the throttle in till it stops accelerating then back off just a bit, otherwise down shift and get the accelerating done quickly.
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Old 10-07-2010, 08:26 AM   #4 (permalink)
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My wife ran her Murano on regular for 32k miles. Premium recommended.
It would rattle backing up our 10% grade driveway, but other than that it ran fine.

Test the different grades to see what happens to your mileage, if you hear knocking consistently then you should not use that grade fuel.

Sometimes the difference in mileage will offset the difference in price, when the engine was designed for higher octane fuel (emphasis sometimes).

I would use the highest gear and lowest throttle position that gets you to the speed you need to merge safely. Since your Acura probably revs 3k at 60 MPH I would try 4th or 5th gear first. Avoid WOT because your consumption will rise dramatically.

When you get the vacuum gauge installed try it at 2 inches without and more than 80% throttle position.

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Old 10-07-2010, 09:49 AM   #5 (permalink)
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Quote:
Originally Posted by bestclimb View Post
I don't really know why a car needs a knock sensor anyway, you can tell it is knocking well before it becomes hazardous if you have the radio turned down to a normal level.
The car will automatically adjust and prevent damage when it senses detonation. We'd have to listen for a little bit and keep driving, which would damage the car before we'd realize it.
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Old 10-07-2010, 12:43 PM   #6 (permalink)
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Quote:
Originally Posted by sevenspeed View Post
I try to get up to or near the 70mph speed limit to merge and have to get onto aa short and steep onramp.
Infrequent short burst (like on an on ramp) will not influence your overall mileage a lot.

Slowing down to 65 or even 60 mph on the highway would easily get your mpg up.

Quote:
Would it be better to use the vtec which kicks in at 4400 rpm?
VTEC wasn't introduced to be more economical, but to give more power.

Stick to the lower revs.
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Old 10-07-2010, 12:45 PM   #7 (permalink)
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If I found the right data for your car on line, you have 10.1:1 compression, so that begs for something to retard knock. My 02 RSX-S has 11:1, so I really have no choice. My guess is you could get away with something like a mid-grade/plus rather than full high octane premium. Most cars that run on the cheap stuff are around 8.5-9.2:1.
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Old 10-07-2010, 12:48 PM   #8 (permalink)
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Give it 60-80% throttle and keep the RPMs as low as this will allow. You want the throttle open as wide as you can get away with without enrichment.
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Old 10-07-2010, 04:22 PM   #9 (permalink)
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Being light on the throttle and letting the revs go higher is horrible for BSFC. I would keep the revs well below v-tec when shifting, like 3000 rpm, and keep your throttle opening high, like 75%. Remember that it is well documented in this forum that brisk acceleration isn`t a bad thing for fuel economy (provided that you are not accelerating briskly to the next traffic light 100 yards away!). Think of it this way: you can be super light on the throttle and slowly accelerate onto the freeway, taking 30 seconds to get up to speed at a horribly high BSFC, or lug the engine (shifting at 3000 rpm in your case) with a 75% throttle opening and be up to speed in 10 seconds at a much lower BSFC. Sure, it burns fuel at a faster rate (GPH) at 75% throttle, but you will be at 75% throttle for a much shorter time.

I actually plan on testing this with my Mazda Tribute V6 soon. I plan on driving a piece of road with a few stop signs late at night when nobody is around. On one run I will accelerate slowly to a speed of 60 kph through the course of the stop and go drive. On another run I will accelerate briskly to the same speed. I believe that economy will be better on the `brisk` run. But I guess we`ll have to see.
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Old 10-07-2010, 05:31 PM   #10 (permalink)
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Moving along with the other traffic is actually close to the best rate of acceleration, but do so in the highest gear that will allow you to maintain that rate of acceleration.

An additional benefit is you are not causing other drivers to get ticked off at you for moving to slowly.

regards
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