Low Accelerations At High Rpms why?

[cliosportap]

i have a superchips remap with max 8300rpm also have kentcams camshafts 258/260
while on full load i recognize that the the revving is very slow after 7500-7600 esspecially at the end of 3rd and 4th gear
but no problem on 1 and 2
if i continue reving after 7600 to 8200 i loose time
but if i change gear at 7600 i see that acceleration is much more better
so what should it cause?
injectors, air flow, fuel presure, or is it normal?

 

[Tom@JMS]

Sounds simply like a typical torque curve.

Depending on the cams the peak torque output could be often anywhere between 4.5 - 6.5k on a standardish/mild camshaft, so after that you will get a significant lose in acceleration as the torque packs it bags and goes home. By changing gear at the correct time you will keep the engine moving through its peak acceleration band of RPM in each gear - where the most torque is present. So it sounds like your are reaching the end of this band at 7600rpm roughly where pursuing more RPM will equal increasingly less output.

Of course its not always this simple as there are other factors to consider like gearing.

8.3k is a seemingly unnecessarily high limiter? however this maybe to suit the cams?

 

[K-Tec Racing]

could also be timing reduction by the mapper

 

[Mike_182]

8300rpm is only going to do two things.

Slow you down, and blow your engine. It doesn't need to rev that hard, you're way, way past where you need to be on the engine to produce torque. And unless you've changed significantly more than cams I'd suspect (but I may be wrong!) that you're likely to kill your engine.

 

[scotty2hotty81]

8300 is too high, no more than 7800 i think.

 

[Andyman]

Get the car rolling roaded and see where your peak power is.

 

[DMS]

8300 does sound very high. You don't have VTEC y0'.

 

[Bazzon]

8300 RPM is high i thought that solid lifters needed to be considered when reving that high.

 

[Riley!]

8300?!?! How high!, I shift about 6,500 on standard cams just cos of lack of power after that, just the way it is

 

[TimR26]

Change when it feels best. Simples.

 

[cliosportap]

in daily use i dont rev much more than 3500rpm
but sometimes i need power. i rev that much maybe 1-2 at 10 days
as i understand i have to change gear approx 7500
i found that the efficient rev band is 2000-7000 for my cams
after 7500 the revving stops

 

[Martin_172]

VVT disengages after 7200rpm which is why your power is dropping like a stone.

reason your not noticing it in first and 2nd is because the car has little resistence so will still rev that high without you noticing the drop

 

[bmh.01]

8.3k , jebus. Note to self: Make sure I don't buy that one.

 

[brutal]

I had explaned you that why you loose power! Optimum shift point for your car is 7200-7500, dont try to get power over 7500rpm. If you want to be a looser or want to blow your engine dont listen what people are saying and rev like a bike with your car! You can easily hurt your tappets and con rods at that rpm. Revving dont give power without suitable camshafts, inlets and mapping. Your engine cant give power over 7500rpm and you cant change it with a maping!

Dostum aracında sorun arama boşuna, 7500rpm in üzerinde daha iyi hızlanma yada güç sakın bekleme, bu arabanın yapabileceği bu, piskolojik olarak nekadar devir çevirirsem okadar güç gelir sanıyor insan fakat bu böyle değil işte. 7200-7500 arasında vites değiştirmeyi dene, bak bakalım kaç boy fark edecek.

 

[Martin_172]

from memory VVT disengages like i said at 7200rpm or there abouts to protect the pistons as the standard ones cant handle prolongued use above that level!

 

[Christophe]

i only go up to 6500 max as otherwise i feel i may blow the engine lol. How far can you got with say a remap from rs tuning?

 

[Martin_172]

well on a standard-ish engine there is no need from an acceleration point of view to go above 7000rpm (i used to find mine dropped off at about 6800rpm so i changed around then) with a raised limiter 7600rpm will be fine but id only be using it when really going for it in first and 2nd gear and mid corner to save a gearchange mid corner unbalancing the car.

 

[skiptontweed]

i have a superchips remap with max 8300rpm also have kentcams camshafts 258/260
while on full load i recognize that the the revving is very slow after 7500-7600 esspecially at the end of 3rd and 4th gear
but no problem on 1 and 2
if i continue reving after 7600 to 8200 i loose time
but if i change gear at 7600 i see that acceleration is much more better
so what should it cause?
injectors, air flow, fuel presure, or is it normal?

You should try putting the clutch in when it reaches 8300rpm in 4th gear, just to see if it revs any higher

 

[franx]

Mine also feels like there's suddenly nothing up there at very high revs, Henk (Fastchip) who mapped the car said it's because of the VVT Disable at those rpm's

Your shift point will be more ideal at lower revs anyway, where the next gear will have the best torque

 

[TimR26]

You should try putting the clutch in when it reaches 8300rpm in 4th gear, just to see if it revs any higher

LOL

 

[cliosportap]

You should try putting the clutch in when it reaches 8300rpm in 4th gear, just to see if it revs any higher

i will try:lolup:
but it makes 230kmh at 4th gear i think no need more than this