A higer redile is no good....

[Cone Killer]

For all you rpm junkies out there who are dissapointed with the Si's redline, consider this. Just by bumping up the redline does not give this car that much more in speed or acceleration. The power is still falling off so it's may work for a little more power, but in too much will be bad. So with out changing the way VTEC works on our car, a redline is not all it's cracked up to be. If you shifted say, at 7,500 you lose out on valuabe torque and power lower in the rpm band. Some times it's better to shift early. Look at this hondata graph.
http://www.hondata.com/images/k20a3basevstune.gif
If you look at the graph and imagine the blue line (hp) continues on a projected path to 7,500. At the rpm it would be making about 110 hp/75tq. Using a gearing calculator, I find that the shift to second puts the rpms at 4333. Ok, so at that rpm the car makes about 97 hp/116 tq. A normal redline (6800 124hp/96tq) yeilds 3929 in second making about 90hp/118tq. The problem I see is that if you go too far with the rpms the car reduces the car's acceleration. This is only my theory of course, but I think you guys get my drift. On a side note, if the redline was 7,500 we could do 69mph in second. That does not mean that our 1-60 times would get any better, but we could attain a higer top speed in any gear.

[Jpax]

Good info......thanks for reasearching it......I was thinking of doing hondadata, and that s awsome.graph.:D

[rick77f]

Too bad it's for a base RSX not an Si. They are tuned differently and have a different intake manifold, throttle body, and the Si has balance shafts. The Base RSX is tuned for bottom, the Type-S for high, and the Si is a bit of both.


However your theory seems good to me except the 0-60. By raising the limiter and allowing you to reach 60 in 2nd, you save time by not having to shift into 3rd.

[02SilverSiHB]

I guess we'll all see when it comes out.....who knows, maybe hondata will work the a/f enough to help out the extra revs they give us.

[Glix2]

As long as they offer us the stock redline option (like the rsx) I'll be getting it.

[JSIR]

yeah that graph isn't that useful. If you end up getting intake, header, and exhaust (basic bolt-ons) then increased revs will definitely help. On my dyno chart the power is still climbing steeply at redline, and would continue to rise probably until 7400 rpms. Torque also takes a jump with these mods. in the upper mid range, so you benefit from shifting later to get you into the best area of the power band, which is right around 6000 rpms. I would do anything for a few more revs, 7500 would be sweet for me. If you dig out my 153.6 whp dyno run on this board (posted by myeverlovinsir - Dyno runs of 3 EP's), you will be better able to see how we can benefit from a few more rpms. I would benefit from a few more rpms and a slight leaning out of the air fuel ration, as this car runs rich at the top end. I could see my car easily hitting 160 whp with the Hondata mod., and running quicker overall. On the initial RSX hondata program they were running 7600 rpms, but the final version came out with 7300 rpms. I hope they allow the Si to run a few more rpms than that, our valvetrain can take it. I think they give us a few more rpms than the rsx will based on the better flowing intake manifold at high rpms. crossing my fingers.

[IceD out N CALI]

Originally posted by Glix2
As long as they offer us the stock redline option (like the rsx) I'll be getting it.

same here:)

[IceD out N CALI]

Originally posted by Glix2
As long as they offer us the stock redline option (like the rsx) I'll be getting it.

same here:)

[ADAMnQuickCIVIC]

Originally posted by Glix2
As long as they offer us the stock redline option (like the rsx) I'll be getting it.

even if they *did* raise the redline, that doesnt mean you can't still shift at the stock redline.
;)

[Cone Killer]

Originally posted by JSIR
yeah that graph isn't that useful. If you end up getting intake, header, and exhaust (basic bolt-ons) then increased revs will definitely help. On my dyno chart the power is still climbing steeply at redline, and would continue to rise probably until 7400 rpms. Torque also takes a jump with these mods. in the upper mid range, so you benefit from shifting later to get you into the best area of the power band, which is right around 6000 rpms. I would do anything for a few more revs, 7500 would be sweet for me. If you dig out my 153.6 whp dyno run on this board (posted by myeverlovinsir - Dyno runs of 3 EP's), you will be better able to see how we can benefit from a few more rpms. I would benefit from a few more rpms and a slight leaning out of the air fuel ration, as this car runs rich at the top end. I could see my car easily hitting 160 whp with the Hondata mod., and running quicker overall. On the initial RSX hondata program they were running 7600 rpms, but the final version came out with 7300 rpms. I hope they allow the Si to run a few more rpms than that, our valvetrain can take it. I think they give us a few more rpms than the rsx will based on the better flowing intake manifold at high rpms. crossing my fingers.

Ok...here's my dyno chart.
http://www.trailingsilence.com/dave/dynomd.jpg
I don't think you guys are seeing what I'm describing. Sure, a few rpms will help, but in general, the power trend on my chart and others I've seen says it falls off around redline, especially tq. The reason is because the engine is designed that way. Just because you add bolt ons or whatever, does not mean that all of a sudden the power curve will change. It won't it will just continue on in predictably, ie....more rpm's less power. It's as if you guys are trying to strech the power band out, when it's just getting worse.

I think a few would help, but I wrote this more for the folks who want the 8,000 redile they are used to and wonder why the K20A3 can't do that.

[Glix2]

Is it me or is there something seriously wrong with your dyno.

Why are you taking a huge dip in power and dropping below 110 hp in the middle of your powerband?

Also why does your torque curve dump out at 116 and never cross your hp line?

Your hp / tq numbers are low even lower than a stock ep are you modded?

[!@#$%]

i agree with cone killer on this one....but you have to remember that the aftermarket is still young for our cars. Nobody has really done any heavy engine work on the A3 yet. My theory is:

Once the hondata mod is out and people have the higher redline (whatever it may be) the real power result will be adding higher compression ctr or rsx-s pistons to the mix, and maybe some ITR camshafts if they fit. higher redline with stock internals is cool....but when higher compression is made then you reap the benefits.

but nobody knows yet on any of this, and the new si seems to be the chaos factor in some aspects. people hitting 14.8,14.9 and others managing 16.4 etc. I think this car will run hard once tuned just right.

[JSIR]

in Cone Killer's dyno chart (and other stock setups ) it is obvious that higher rpms would not help much as hp is flattened at the stock redline.

The relatively few mods on my car did change the power/torque curves a fair amount as my torque now peaks around 6000 rpms at 129 ft lbs to the wheels, the mid range dip is gone, and top end torque is still fairly flat. My torque at 2000 rpms equals that at 6800 rpms - fairly flat curve. I still have almost 120 ft lbs of torque at 6800 rpms (redline) , so I have to say the torque/power curves can change a decent amount with just some cheapo bolt-ons. I would like to shift at a redline level in each gear that gets me as close to 6000 rpms as possible, right now I end up far below that on every gear change. I am only talking about my setup here which has I/H/E/TB, but most other I/H/E setups come almost as close.

Surely, no one here should be thinking of 8000 rpms, that just won't work on an under-cammed car as this, not to mention valvetrain limits. But 7500 would make me very satisfied, 7400 rpms would be good (same as the old H22's), 7300 rpms would be barely adequate.

[DjMacAtack]

all this talk of higher rpm not being better and yet nobody has mentioned the valve springs...

doesnt the hondata site suggest stiffer valve springs for the higher rpm's??

i was under the impression that if the RPM band gets too high for the valve springs it would cause floating which causes HP loss...

please correct me if i'm waaaay off

[Mechanic]

Can I add something here you might want to keep in mind?

Others have mentioned this before, but it bears repeating. The ECU has a memory. If you miss a shift at max rpm resulting in mechanical damage (broken valve springs, valves striking pistons, or other evil stuff), the ECU will record all the related data, including the engine RPM when then the failure occurred. That tends to make for some very interesting conversations regarding the limits of the manufacturer's engine warranty. Thus, while most shops will cut you some slack if your car is stock when you miss a shift, if you've modified your engine in any way (even adding a header), your warranty is probably toast. (This, by the way, explains why most aftermarket companies wait at least two full years before producing performance products for a new engine series -- to ensure that they won't start a war with Honda over whether a particular part is related to any OEM warranty claims.)

[02SilverSiHB]

Originally posted by DjMacAtack
all this talk of higher rpm not being better and yet nobody has mentioned the valve springs...

doesnt the hondata site suggest stiffer valve springs for the higher rpm's??

i was under the impression that if the RPM band gets too high for the valve springs it would cause floating which causes HP loss...

please correct me if i'm waaaay off
I know what you're talking about, and yes they do say that, on some applications. On other applications they say it won't hurt. So with them raising it only about 500 more, I'd say we're okay.

[myeverlovinsir]

If you read through what JSIR has posted here, and refer to the dyno (http://ephatch.com/forum/showthread.php?threadid=3949&highlight=Dyno+runs) results.
Base RSX is not an Si. There is much more in our upper rpm band
than the above rsx dyno chart shows.
The best reference for this thread would be our own dyno results and not some poor comparison of the base RSX. hth.:D


http://www.trailingsilence.com/dave/dynomd.jpg

Wow your dyno is real peaky torque wise. Did you dyno in fourth?
I for one am really surpised you did not break 120ft-lbs in torque
and just kissed the 130hp marker, does not seem right for
the baseline Si. (121.8 torque 137.0 wHP) comparision stock run.

[Cone Killer]

Originally posted by myeverlovinsir
Wow your dyno is real peaky torque wise. Did you dyno in fourth? I for one am really surpised you did not break 120ft-lbs in torque and just kissed the 130hp marker, does not seem right for
the baseline Si. (121.8 torque 137.0 wHP) comparision stock run.

I had about 600 miles on the car at the time, and I think the dyno was done in 3rd. My best 1/4 is around 16.1-3 so I'm sure I have more power since the break in period.

[CleanBlackSi02]

What about this dyno with just a CAI...it seems to be making HP until he shut down...

Regardless, I'll be getting Hondata with the 7300 rev limit...I'd like to know I have it just in case. ;)

[Jpax]

:eek:

[JSIR]

Cleanblacksi02, you still need some more breathing mods to benefit from the extra revs but your curve is improving. The rougher appearance of your curve as it nears redline is due to the overly rich mixture at those rpms, so you would benefit from a leaner fuel mixture and extra revs, something the Hondata ecu program does . Our cars run a tad on the rich side at WOT and high rpms.

[CleanBlackSi02]

Actually it's not my dyno...but I'm sure my car would be similar. ;)

[JSIR]

sorry didn't realize that, but yes you are right, they all do that.

[Cone Killer]

Originally posted by CleanBlackSi02
What about this dyno with just a CAI...it seems to be making HP until he shut down...

Of course it's making hp...but it makes less and less, ie...the slope of the line is reaching 1. The power is related to the cam and the cam is not designed to make "more" power past redline. So that's what I mean when I say more rpms are not nessasarily good.

[myeverlovinsir]

Originally posted by Cone Killer


Of course it's making hp...but it makes less and less, ie...the slope of the line is reaching 1. The power is related to the cam and the cam is not designed to make "more" power past redline. So that's what I mean when I say more rpms are not nessasarily good.

I agree, we are limited in the amount of torque available. The
hp factor is just really nice when you live between gears on
a track, an extra 1k rpm, just makes the next gear that much
stronger. I imagine this would help in AutoX nicely.:)

http://www.imagestation.com/picture/sraid40/pb8553613864f81d306ea00e386f7a0fe/fcfce721.jpg