RPM's

[bigbrat41]

With a list and lots,lots, and lots of notes for planned mods I want to take the Lxi to the strip for a few runs to use as a baseline for comparison later.
So i have been practicing my shifting ( my road has along stretch with nothing but cattle to laugh if i miss 2nd).
Question is
At what RPM do i become concerned that the A20 will come unglued?
I know that the factory 6300 redline is quite conservative. the motor is bone stock. all input will be greatly appreciated.
thank you
bigbrat41
aka; GREG :rockon:

[Legend_master]

With a list and lots,lots, and lots of notes for planned mods I want to take the Lxi to the strip for a few runs to use as a baseline for comparison later.
So i have been practicing my shifting ( my road has along stretch with nothing but cattle to laugh if i miss 2nd).
Question is
At what RPM do i become concerned that the A20 will come unglued?
I know that the factory 6300 redline is quite conservative. the motor is bone stock. all input will be greatly appreciated.
thank you
bigbrat41
aka; GREG :rockon:


Don’t shift past redline, unless you have built the motor for it. Its called redline, because that is the point at witch engine destruction occurs unless properly built. I also think that there is a rev limiter that will not let the motor rev past redline (but I am not sure about what years have the rev limiter).

[88eyeguy]

the powerband ends before redline if i recall...so why would you want to shift after the redline w/ a bone stock accord?

[bigbrat41]

i'm working out the shift points, take off r's etc. i have purchased a Gtech Pro to help me maximize my efforts prior to embarassing my self at the strip. rgarding the powerband and redline i just do not want to limit myself if i can continue to develope power a few rpm's past the factory redline.

[Legend_master]

i'm working out the shift points, take off r's etc. i have purchased a Gtech Pro to help me maximize my efforts prior to embarassing my self at the strip. rgarding the powerband and redline i just do not want to limit myself if i can continue to develope power a few rpm's past the factory redline.


You not limiting yourself, First thing you have to look at is that THE ENGINE WILL SUFFER FROM OVER REVING and like 88eyeguy said IT QUITS PRODUCING HP BEFORE REDLINE. Just get some mods done to the head and rebuild the bottem end and you should be able to rev a little higher.

[shepherd79]

the way i found out is that the best thing is to lunch at about 2500rpm and go from there on bone stock motor. don't take past 6200 rpm, around that area the fuel will cut off.

[Versanick]

6950, and it will bounce off of it at WOT.

I used to show people that I could rev my old carb'd a20 (bone stock) to 8000rpm for seconds at a time. I even have a picture of the tach (or many) at 8000rpm. I would rev to 7000 sometimes on the street in first gear so that when I hit second gear, I was pounding the middle of the torque peak, then shifting at 5800 into 3rd.. I haven't played with many lx-i's, but if your power's really cutting off, it's a bad idea anyway.

[racerx]

nice. and i bet your compression is about 50% of what it should be now... and prolly variant by 40-50% too.... :( that's what the prior owner of my prelude did. #1: 110, #2: 95, #3: 35, #4: 105
nice, huh? the PCV was about to explode with excess gases blowing by the piston rings.
leak down test showed 80% loss in #3....

...but it gave me an excuse to buy a B20A

[SteveDX89]

Max power is 5500 rpm. Shifting anymore than 6K is a waste.

[racerx]

Max power is 5500 rpm. Shifting anymore than 6K is a waste.

but....... that's not what they did in F&F ......... oh, and where can I get a 10-speed transmission?

[Legend_master]

but....... that's not what they did in F&F ......... oh, and where can I get a 10-speed transmission?

dude dont you know you only get that if you live in the shop and have NOS. Back to the subject I think the carbed motors can rev to whatever you want (within the limit of the motor), because they do not require an ECU.

[racerx]

lol.
anyway, while a carbed motor might not require an ECU, any car with more than just an engine, fuel line, and clutch cable WILL.
there's a lot of electrical controls and vacuum diaphrams that are all monitored and controlled by the computer.

[gfrg88]

i agree with cke.

[mykwikcoupe]

wellthe revs have a point but in a different perspective. in basic theory in an overdrive setup each 1k rpm equals out to 10 mph so if your trying for max speed ok. In a drag where hopefu;;y your not having to shift out of third (only becuase it takes time and a quick lose of power) you definatly not gaining anything. Im learning drag ive been an auto-x guy for a while. Find out what works with your tires and practice. See what happens with a quick 1-2 gear shot and pull 3rd to the 1/4 mile or redline see what comes first.

Oh and about the prelude. thats bad man. sorry to hear that.

[SteveDX89]

lol.
anyway, while a carbed motor might not require an ECU, any car with more than just an engine, fuel line, and clutch cable WILL.
there's a lot of electrical controls and vacuum diaphrams that are all monitored and controlled by the computer.

If you're talking about the thing under the driver seat, it's not an ECU. It's a solenoid control box. You're correct about what it does but it's technically not an ECU.

[EvilPenciler]

stroke it, megasquirt ( do your injectors, FCD, and all that neat stuff then) it, then boost it. Then do an exhuast ^_^. You may want to take a look at swaping a auto gearing in (they are lower) lower gearing means faster accelleration slower topspeed higher gearing means higher top speed slower acceleration. Dont forget your suspension either f00.

[Baveara]

my carbed g will not stop it just keeps revving and revving so maybe my rev-lim is brokein.

[snoopyloopy]

i know my 89 lx-i cuts the fuel at the redline. it won't rev past it at all. i've tried/accidentally hit that.

[88eyeguy]

mostly because they never expected some idiot like me to rev the crap out of 'em all the time. i miss my a20a1...

[FyreDaug]

Well if a 6000rpm shift brings you below the powerband shifting at 6500 would put you closer to it. I bet it makes more power at 6500 than it does at 3000.

[racerx]

this is an old ghetto image i made a while ago, but it gets the point across.
the ideal shifting point is the one that gives you the most area under the curve, and thus the most power when driving.
you want to stay as high as possible, for as long as possible. this gives you the most power, most efficiently.
http://memimage.cardomain.net/member_images/6/web/558000-558999/558113_14_full.jpg

if you shift too high, you're not staying under your power curve. if you shift too low, same thing.

there is an ideal point where you will shift and remain on equal sides of your maximum power.

the only time you want to shift as high as possible is when your horsepower curve does not fall off at any point below your redline. however, in a mostly stock 3rd gen, or even one with most bolt-ons, your power will still fall off.

[SteveDX89]

Well if a 6000rpm shift brings you below the powerband shifting at 6500 would put you closer to it. I bet it makes more power at 6500 than it does at 3000.

Peak power is 5500. If you wait to shift over that, you are not accelerating as fast as if you'd have shifted. Since power drops off, you aren't accelerating as fast. Based on racerx's chart, I'd shift at 5500 at the most.

[FyreDaug]

Well I dont specifically know the power band, but it usually rises faster than it drops.

So lets say 5500 makes the whopping 100hp. 6500 lets say would be about 75-80, but 3500 would be 65-70. But then again I dont know, just making the assumption. My engine with I/H/E/Ignition seems to pull best after 5000+ :dunno:

[racerx]

the best place to shift would be where you stay at the highest power the longest.

normally, that's still past your peak HP. you'll be bouncing back and forth over the peak HP point, maximizing your accelaration.