Why???????????????????????????????

Stock valve train=stock rev limiter.

You bend a valve and your engine is blown. Its really your call but it sounds pretty fucking stupid to me.

 

because my engine makes more power the higher it goes..

and i've read before that about 8grand is the limit for the stock valvetrain,
I just wanted to ask for myself.

and for an n/a d15b.. I really wouldn't even ask, I'm sure it'd be fine.

 

it's not just the valve train but the cylinder wall loads you have to worry about, too.

 

because my engine makes more power the higher it goes..

and i've read before that about 8grand is the limit for the stock valvetrain,
I just wanted to ask for myself.

and for an n/a d15b.. I really wouldn't even ask, I'm sure it'd be fine.

Um, you arent going to make more power.

http://home.comcast.net/%7Etadman3d/d15bdynA.JPG

Thats your dyno sheet right? You dropped almost 20 ftlbs of torque over 2000rpms and you think you are continuing to make more power???????????

A little math for you, we'll say at 5700rpm you were making 134ftlbs of torque. at 7800rpm you are making 117ftlbs of torque. at that rate of change(which is pretty consistent) it forms a line. the fomrula of that line is y=-17x/2100+180. so at 8000rpms you will be making a whopping 115wtq and 175whp. WAH FUCKING HOO AN EXTRA 2 HORSE POWER!!!!!!!!!!!!!

You are already revving tha engine out more than you should for an extra 8hp.

Do what you want, I dont give a crap. You will see absolutely no benefit of revving to 8k and you will end up with a blown engine in a matter of a few weeks. Revs kill engines. If you arent meant to rev to what you are revving to your engine will let you know shortly. Good luck, you're going to need it.

 

doesnt make more torque,
but as I said,
it makes more power.
at 5700 that chart shows 145whp, at 7800 it shows 177whp

and yeah, I just asked for opinions,
so rip that huge stick out of your ass and calm ur shit down man.

I wanted to hear what people thought, and you gave your opinion, so thanks
don't see why you are getting all huffed up and high and mighty.
I already shift at around 7.5k anyways, so it's mostly curiosity..

though i'm still sure that 600rpm past the stock cut isn't going to ruin my engine "in a matter of weeks"
so I will argue you on that point,

 

rev to stock limiter, you arent making any significant gains up that high, and you're just asking for trouble. personally i rev to somewhere in the 7200-7500 range. all it takes is one moment to bend a valve, could happen in 6 months, could happen in 10 minutes, might never happen, but you never know.

 

1.5's are good on boost until you start getting greedy(not GREDDY), i got boost happy and took my 1.5 to 17psi it couldnt handle it and also if your makeing more power your probably leaning out. usualy at topend if your car starts pulling you are probably doing damage. under leaner conditions a motor tends to make a little more HP. especially on a boosted car unless the motor is sleeved dont go above stock redline. i know on a N/A car you can take it to about 9K on a stock valve train but your not filling the cylinders with as much pressure as a Boosted motor.

 

doesnt make more torque,
but as I said,
it makes more power.
at 5700 that chart shows 145whp, at 7800 it shows 177whp

and yeah, I just asked for opinions,
so rip that huge stick out of your ass and calm ur shit down man.

I wanted to hear what people thought, and you gave your opinion, so thanks
don't see why you are getting all huffed up and high and mighty.
I already shift at around 7.5k anyways, so it's mostly curiosity..

though i'm still sure that 600rpm past the stock cut isn't going to ruin my engine "in a matter of weeks"
so I will argue you on that point,

horse power is directly related to torque. You cant calculate horse power without torque. So your torque drops fast enough your hp does do. gaining 2hp theoretically by increasing your revs 200rpm is not a significant power gain. When people say they are making more power it means their torque is actually holding consistant so their hp will increase at a moderate rate. 2hp over 200rpm is far from an increase worth risking your motor over.

And yes, revs always kill engines. Stock valve train is not meant to rev over the fuel cut. its the way it was designed. revving 200rpms past it is just "okay" anything past that is simply retarded. 2 HP isnt making more power so give me a break.

Thats like taking a shit and going on the scale and losing 2lbs and calling it a weight loss.

But then again "peoople have told you its okay" so it must be. People also tell me you cant make double your horse power on a honda and have it reliable and that AEM EMS can make more power than the stock ECU.

Do a simple risk analysis. You can 2 hp but take your valve train past the point where its acceptable thus for that 2hp you are putting your engine in serious jeopardy. Is it worth it? Make a decision and live with it. If you raise your revlimiter, tell me how many times down the track shifting at ~7800rpms it makes it.

 

If you want to rev it to 8000, then do it. D15b's do respond well at 8000, due to the rod stroke ratio. The stock valve train might be limiting the engines power up there, and you may even see some valve bounce. Install a set of hardened valve springs and retainers with a camshaft to ensure proper breathing at upper rpms.

Other than that, rev your ass to 8k all day long. My D16 revs 8k with cam and springies, no worries.

 

i wouldn't do it.

the few extra ponies you gain won't offset the longevity you'll erode from your motor. i only go over 5k rpm when i'm on the on-ramp on highways anyway... no need to go past that all the time.... you race every day or something?

 

horse power is directly related to torque. You cant calculate horse power without torque. So your torque drops fast enough your hp does do. gaining 2hp theoretically by increasing your revs 200rpm is not a significant power gain. When people say they are making more power it means their torque is actually holding consistant so their hp will increase at a moderate rate. 2hp over 200rpm is far from an increase worth risking your motor over.

And yes, revs always kill engines. Stock valve train is not meant to rev over the fuel cut. its the way it was designed. revving 200rpms past it is just "okay" anything past that is simply retarded. 2 HP isnt making more power so give me a break.

Thats like taking a shit and going on the scale and losing 2lbs and calling it a weight loss.

But then again "peoople have told you its okay" so it must be. People also tell me you cant make double your horse power on a honda and have it reliable and that AEM EMS can make more power than the stock ECU.

Do a simple risk analysis. You can 2 hp but take your valve train past the point where its acceptable thus for that 2hp you are putting your engine in serious jeopardy. Is it worth it? Make a decision and live with it. If you raise your revlimiter, tell me how many times down the track shifting at ~7800rpms it makes it.

I love this guy!

 

the best thing you can do is lighten the car up as much as possile. drop the reat seat and clean the car of everything not bolted down including the carpet for a good track run. take the pass seat out too along witht he center console. and see what it does. you'll more than make up for any 2-10 or even 20 hp gain by overreving the engine with weight loss.
Every 60-75lbs is like .02 of a second. if I remember correctly on average.

 

too much math in this thread....anyone have a T-83 I can borrow?

 

too much math in this thread....anyone have a T-83 I can borrow?

I have one of those... haven't used it since college though, it may need batteries!

 

Um, you arent going to make more power.

http://home.comcast.net/%7Etadman3d/d15bdynA.JPG

Thats your dyno sheet right? You dropped almost 20 ftlbs of torque over 2000rpms and you think you are continuing to make more power???????????

A little math for you, we'll say at 5700rpm you were making 134ftlbs of torque. at 7800rpm you are making 117ftlbs of torque. at that rate of change(which is pretty consistent) it forms a line. the fomrula of that line is y=-17x/2100+180. so at 8000rpms you will be making a whopping 115wtq and 175whp. WAH FUCKING HOO AN EXTRA 2 HORSE POWER!!!!!!!!!!!!!

You are already revving tha engine out more than you should for an extra 8hp.

Do what you want, I dont give a crap. You will see absolutely no benefit of revving to 8k and you will end up with a blown engine in a matter of a few weeks. Revs kill engines. If you arent meant to rev to what you are revving to your engine will let you know shortly. Good luck, you're going to need it.

So with that I think that comes out to a loss of 17 ft/lbs per 2100 RPM? I'm not sure but it's enough to scare me not to rev my engine past the stock rev limiter.... well maybe no more then 400rpm past in a race where I would need the extra hp maybe. :???:

 

Power doesnt cause valve train faliure, if it did people wouldnt be running 550whp on a Stock GSR/B16/ITR heads. Revving past their tolerances does. So if this car's rev limiter is 7500 hes taking it 500rpms past it just to gain esentially 3-4hp.

Like i said, figure out the risk involved and if you can afford to blow an engine. If you dont really care if it blows or not, rev it out and have fun. If your thinking was reliability, then dont do it. Risk analysis

And the whole point of showing the torque was losing was because as mentioned before HP=Torque*rpm/5252. Torque=decreasing directly effects the rate of change of the HP. Thus he is really making peanuts as far as power increase but he said "im still making power"

 

Power doesnt cause valve train faliure, if it did people wouldnt be running 550whp on a Stock GSR/B16/ITR heads. Revving past their tolerances does. So if this car's rev limiter is 7500 hes taking it 500rpms past it just to gain esentially 3-4hp.

Like i said, figure out the risk involved and if you can afford to blow an engine. If you dont really care if it blows or not, rev it out and have fun. If your thinking was reliability, then dont do it. Risk analysis

And the whole point of showing the torque was losing was because as mentioned before HP=Torque*rpm/5252. Torque=decreasing directly effects the rate of change of the HP. Thus he is really making peanuts as far as power increase but he said "im still making power"

This is how you know a motor is well built or designed... the torque curve should remain essentially flat (ideally) ater the torque peak. The faster it drops off, the less peak horsepower the motor ends up making.

Torque curves that drop that fast generally have a good reason for doing so... in this case, most likely the cam profile isn't intended to make power in that range. Also, it is S/C, so the charge temps are GOING THROUGH THE ROOF, which will also drop that torque curve.

Someone please correct me if this is inaccurate.

 

Ok...here are your options. Don't take your motor to rev limit of holy proportions and be happy you have a car to drive. Do take it up there and have it blow...then come here and post a thread asking why your motor blew and we can all laugh.

Drive it normal capt. street racer.

 

This is how you know a motor is well built or designed... the torque curve should remain essentially flat (ideally) ater the torque peak. The faster it drops off, the less peak horsepower the motor ends up making.

Torque curves that drop that fast generally have a good reason for doing so... in this case, most likely the cam profile isn't intended to make power in that range. Also, it is S/C, so the charge temps are GOING THROUGH THE ROOF, which will also drop that torque curve.

Someone please correct me if this is inaccurate.

Thats the idea

Remember though that if the car is more low end/midrange minded your cam/head/intake design will most likely not hold a peak torque to redline because it would have to hold it for a while and its hard to design a part to do everything well. So on a car like a WRX it might not hold the torque after peak but the cars design was more of an auto x feel so it will have a nice full bodied torquey midrange.

 

Guess I've always been looking at the dyno queens with huge turbos that spool at 5k... makes perfect sense.

 

Yeah I think my mindset with this motor is "reliability while it's in there"

not too worried about the motor lasting 100,000,000miles or anything,
as i'll probably feel like throwing someting different in there eventually..
but for NOW i AM happy with it, so I don't WANT it to blow of course.

Also imo theres always that "buffer zone" with honda's tolerances/clearances and such.. if they put the stock revlimit at 7400, then going to say 7800 really isn't
the big deal you guys make it out to be.
especially with a d15b which has such a nice r/s ratio, cyl pressures wont be as bad as say a z6 or your average 1.5.

you guys are right though, engine definetely isn't making enough up there to warrant going all the way to 8k, I think if I get the chance i'm going to drop the cut down to 7800, and shift at around 7500.. that's prettymuch the sweet spot.

that and my top end could use alittle more tuning,
we ran out of time (or rather I didn't want to spend anymore money) on the dyno
so my top end is super conservative, I think there are tq/hp gains up there to be had just by leaning it out some and adding some more timing.
not to mention i've still got the stock header!!

 

One thing I forgot about. The rev potential is also limited by the bottom end.

Factors include: Motor balanced (up to what speed?) and also rod bolts. Revving too high on a stock bottom end will invariably stretch rod bolts and spin a bearing.

 

shifty, honda stock motors are already balanced. the only time you have to re-balance is if you change parts inside out. like the clutch plate, pulley, rods and pistons any of those will throw the stock balancing off. but if left alone, it's fine. the clutch plate is not as mush of a change as lets say rods or pistons or a pulley (going from the small stocker to a larger stocker)

 

So you're saying my bottom end is safe to rev to 20k RPM?

Just kidding. What about rod bolts, shouldn't those be replaced?

 

You rarely need to balance your engine after piston/rod/crank/blah blah blah installs because those companies use machines worth more than my life to balance all their parts before getting sent out.

If i were revving to 10.5k or something i might invest in balancing everything, but otherwise i dont think its necessary at all