OBD conversion - Chipped/Tuned P28

BlkCurrantKord · Apr 7, 2008

Yeesssss....

AFAccord · Apr 7, 2008

Totalimmortal said:
I believe the Canadian Accord had the same motor as ours, no?

BlkCurrantKord said:
Yeesssss....

Lurkers... lol :lurking:

BlkCurrantKord · Apr 7, 2008

Interesting debate....always good to learn something.

Something to add to the mix...

My old dyno graphs show me making peak Hp/Tq from 4750-5200rpms, I'm assuming thats the VTEC engaging, granted its an auto and the graph starts at 4k.

simplesedan99 · Apr 7, 2008

man...im gona go hide under my bed till this ones done :hide:

S-spec · Apr 7, 2008

Post Edited Above

AFAccord · Apr 7, 2008

S-spec said:
EDIT:

Alrighty. After all this discussion, I went ahead and made a 2$ VTEC light using an old turn signal from a Civic. AFAccord is 100% right.

Although the stock F23 ECU uses a VTEC window between 2500 and 4000 RPM. Under high load, VTEC engages at 2500. Under low load, the latest VTEC will engage is 4k.

My apologies

It's all good man. Just trying to get the right info out there to all the guys (and gals) on the forum. F23's are a very misunderstood breed. It's all about smooth bottom end with this motor. :driving:

Fuzz · Apr 8, 2008

S-spec said:
Post Edited Above

You forgot to pay for the car rental :bash:

I'm interested in knowing why there is a noticable difference in the intake note at 5200. I know you never 'FEEL' it with these cars, but its easy to tell based on sound.

Oh well!

Sonnick · Apr 8, 2008

Stock VTEC engagement on an F23a1/4 motor is ~2300-2500 RPMs. Some are mistaking the F23s VTEC as performance VTEC, which is untrue. Despite the appearance, the Accord Coupe is a family coupe, not a sports coupe. The SOHC VTEC in the F23 was designed for gas mileage purposes, actually.

And there is no low cam/high cam on the F23 as it is a SOHC motor.

NASOHC: What were your dyno numbers with that cam?

AFAccord · Apr 8, 2008

Fuzz said:
You forgot to pay for the car rental

I'm interested in knowing why there is a noticable difference in the intake note at 5200. I know you never 'FEEL' it with these cars, but its easy to tell based on sound.

Oh well!

You have a short ram intake possibly? The pitch at which the motor's sound changes could be directly related to the length of the intake, a little principle called harmonic resonance.

Taken from the following post.

http://www.6thgenaccord.com/forums/showthread.php?p=82335#post82335

6thGenAccordMember said:
typically SRI gives you better low end and CAI is top end.

AFAccord said:
In fact, the opposite is true.

Take a trombone for example. Pull the slide almost all the way out and you have a long tube. Send reverberated air through this tube, and you get a low pitch sound. Now pull the slide all the way in, and your tube is much shorter. Send that same frequency of reverberated air through the shorter tube, and you have a much higher pitched sound.

This is the EXACT same effect different intake lengths (SRI vs CAI) have on a motor, but to understand this, you have to understand harmonic resonance. There isn't a very easy way to describe this, but there is an excerpt that you can read below to possibly help you understand, or just possibly confuse you further. You can read it and learn, or otherwise just accept it as fact.

" If, at any one constant throttle and constant rpm, you could adjust the LENGTH of the intake system, you could find a correct length so that the REFLECTED pulse of air from a closed valve, hits an open intake valve at an exact moment as a normal incoming pulse of air. This will have the effect of boosting power, as more air will be forced into the cylinder...at NO cost whatsoever in loss of energy."

This example is for a CONSTANT throttle and RPM, so a typical well designed intake has a particular frequency (engine rpm) that its harmonic resonance is most effective for the overall motor. Several car manufacturers have made attempts at 'adjustable' intake lengths, including Honda. This is where engines like the F22A6 get their dual runner intake manifolds from.

So how does this affect you? Well, if you choose to use a SRI on your 2.3L accord, the piping is shorter, with less volume, and has a higher effective harmonic resonance. Likewise, with a CAI, the effective resonane of the intake is lower. So those with a CAI will experience better low and mid-range torque, whereas those with SRIs will experience a seemingly better top-end experience.

I say 'seemingly' because the 2-3hp top-end gain you feel is exagerated by the 4-5wtq loss in the mid-range.