How to Accelerate?

[thebrad]

Originally Posted by Vince-HX

A tuner informed me that honda's dont go into open loop unless throttle is over 90% and rpms are high enough.

I accel @ 0-1 in vacuum (about 75%) and always pulse from 1500-2000 rpm. This has given me high 60's in city driving.

Ha, I shift at 1500.

[Daox]

Shifting sooner is not necessarily better. It depends on the engine. Most engines are more fuel efficient around 2500 rpm.

[pumafeet10]

Vince- i was hoping to hear from you, there was a post recently on ht where you had talked about your experiences and then seeing your employment with full race had the wheels turning wondering if you and the guys there had any crazy new parts that you have fabricated. I also seem to be folowing your recipe for my acceleration as well with the pulse and glide, sadly i don't regularly commute in my hatch so i haven't been able to hone my skills on a daily basis

[Vince-HX]

based on that most efficient mean piston speed formula my optimal shift points are between 2000-2500.

2000 works for me, I still have a pretty good accel rate and that style of driving corresponds pretty well with my factory shift light.

[thebrad]

Originally Posted by Daox

Shifting sooner is not necessarily better. It depends on the engine. Most engines are more fuel efficient around 2500 rpm.

It's pretty much ingrained in the way I drive, plus it lines up with the shift values recommended in the owners manual.

[Vince-HX]

Originally Posted by pumafeet10

Vince- i was hoping to hear from you, there was a post recently on ht where you had talked about your experiences and then seeing your employment with full race had the wheels turning wondering if you and the guys there had any crazy new parts that you have fabricated. I also seem to be folowing your recipe for my acceleration as well with the pulse and glide, sadly i don't regularly commute in my hatch so i haven't been able to hone my skills on a daily basis

We always have crazy new parts and ideas

Its great working @ a fab shop like Full Race. I have access to some of the best tooling available and some of the smartest engineers I know. The best part is that the bossman is all for trying out new ideas and combining power with FE. I'm very lucky to say the least.

And trust me, ideas are flowing

here is a little teaser - Ive made a device that has low 50 degree output temps without the use of a AC compressor

[pumafeet10]

well seeing the quality of work and your somewhat seemingly quick results speak for themselves which pair that with you have a civic very similar to mine makes me follow most of the stuff that you are doing. And any new stuff you need a guinea pig for or someone to do trial and error with im all for it. Im trying to understand more of the science behind how our motors work but its hard to keep up sometimes.

I will say keep up the awesome work , and let me know when you get the contraption for cooling ready i want a piece of that!

[bbjsw10]

Originally Posted by Daox

I aim to always (regardless of speed) accelerate at around 80% load

What do you mean by 80% load? I am just learning on this. How do you figure load %'s?

[tasdrouille]

Originally Posted by bbjsw10

What do you mean by 80% load? I am just learning on this. How do you figure load %'s?

You get it from the scangauge. AFAIK it's the percentage of total available power (or is it torque?) for any given rpm you are currently using. Imagine the power curve in your head, the load is where you are in relation to the power curve (which is 100%).

[pumafeet10]

which as posted above pretty means where you are closest to your optimum bsfc, i think thats correct. Also you can find out the load on you engine with a scangauge or using a vaccuum gauge

[azraelswrd]

Yep, BSFC map is your friend in visualizing it.
I couldn't find one for my own car but I know there was a topic about them here. This is an article from Autospeed about them with a few example maps:

Brake Specific Fuel Consumption

[badaz907]

I know I have the more powerful engine at 127hp vtec, but i find that while looking at my vacuum gauge the best vacuum occurs at 2500-3000 rpm, so you guys always talk about driving under 2k rpm but when i do in my civ vacuum remains low in or around 0-5 full throttle because it doesnt seem to have enough torque to move. what I'm asking is how to drive my civic in the city its a 5 speed so light throttle to get moving and coasting at 3000 to obatian best vacuum is this correct. I need a clear answer , most posts are a bit confusing please help.

[pumafeet10]

well most cars are different but most of us with one of the d16 varieties have seen the best results staying between 1500 and 2500 at most but someone like me has gotten best results shifting at 2000rpm that way you also can keep your speed down easier, you just need to see what does best for you accel and shift at 2k, 2500, or 3k and then report back. Since i have a scangauge i use engine load which i keep at about 75

[badaz907]

I can use the vacuum to see engine load, basicly lower the vacuum the more throttle im giving it, I would get a scan gauge but I find that they are too costly, the vacuum gauge was 20 bucks however on this tank with the spoiler removed new dist, 40 psi in the tires and grill block i think i am currently getting 36-40 mpg city

[bbjsw10]

I get roughly 18-20in. hg. at idle and accelerate at 10in. on vacuum gauge where would that fall in load %'s. Just to give me an idea, I tried reading the link posted but got lost over my head I guess.

[pumafeet10]

from what i have seen that you want too see the most amount of vac for the least amount of fuel used, higher vac means the throttle is closed hte most there for creating a vac in the intake manifold

[Vince-HX]

Minimize pumping losses while accelerating.

Accel - least amount of vac without going into open loop
Cruise - highest amount of vacuum @ efficient rpm

imo

[PaleMelanesian]

I like to accelerate at about 50% throttle at lower speeds, working up to about 80% at higher speeds and gears. Something like this:
1st gear: just to get moving. Shift before 5mph.
2nd gear: 50% throttle
3rd: 60% throttle
4th: 70% throttle
5th: 80% throttle pulse, then glide, then pulse again

Watching the scangauge, these throttle points roughly correlate to 70-80% load in each gear. At low speed and rpm, there's less power available, so it takes less throttle to reach the same load %.

80% load is about 12 on the MAP gauge, so near WOT but not quite there. I find that my Honda will go to Open Loop at about 90% load.

[sickpuppy318]

Originally Posted by Vince-HX

Minimize pumping losses while accelerating.

Accel - least amount of vac without going into open loop
Cruise - highest amount of vacuum @ efficient rpm

imo

wow, thanks for putting it so simply
And i think i'd take your oppinion anyday because for a while there i was a tuner mag junkie and always loved the full race stuff. I don't generally "like" hondas but, well, you know, you work there.

i dont have any instrumentation (gauge cluster doesn't even work), but just driving my three speed tercel to work today with that little tidbit in the back of my mind, i think i've "modded" my technique for the better.

thanks for the insight.

[pumafeet10]

so in watching lod on the scangauge you want 70-80% of the maximum out of your engine therefore keeping it in its maximum bsfc atleast that is where it would be for the honda guys here with the 1.6l engines