What is Redline?

LXSC

Registered User
This question may seem sort of simple but anyway, I want to know what Redline should pertain to on any given car and how it can be calculated for specific setups.
 
Ok what they mean by Redline is that big *** red line that if the needle crosses over... The ECU will kill the engine or try to kill it in order to keep you from blowing the shiz niz out of it. You can chip any car to eliminate the redline but be warned that if you cross into the redline with a chipped ECU you are risking of REVVING OUT the engine and send it on a one way trip to the salvage yard. Hondas have chips to eliminate REDLINES but many of them blow up their engine thinking it is safe. I for once like to know that my ECU is protecting my engine from my stupidities.

Also. remeber the smaller the engine. the smaller the crankshaft. The higher redline it will have. I believe you can redline higher if you rebuild your engine with RACE PROVEN HIGH QUALITY parts that you know wont disentergrate at such high revolutions.
Why do you think HONDAS redline like at 8K Rpms. And RX7s like at 10K. The smaller the engine the smaller the crankshaft and the faster it will rotate.
 
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My redline is 6K. Anything after that and my ECU kills my engine. Its happened during before during a race. For a NA 3.8L it should be like around 5k. But i doubt anyone will take a NA that far.
 
my sis has a 90 cougar base model with the 3.8 and the redline is 5000 like the sc's and it takes forever to get to redline in it
 
redline on a supercoupe is 5000 or 5100 (i say 5100 becuase the 5000 mark on the tach isn't red.. anyway...) i think what darkstar is talking about it the rev limiter which is actually 1,250 ABOVE the engines redline. the rev limiter is there as a last defense against potential engine damage. It kicks in at 6,250 i believe.
 
NO_FUEL_RPM 6000 # Max RPM (no fuel)
This is the factory rev limiter function. Since HP peak occurs on a stock SC at about 4600, there is no need to rev beyond 5200. A reasonable Redline would be 5700rpm. You don't want to invoke the no-fuel rev limiter if at all possible as it is very hard on parts.
 
haha rx7s have a rotary, no crank. my moms car is a 94 mustang 3.8 v6 5 speed and it reds at 5000. doesnt take long to get there, just a slow car any way. high 16s i think, 145 or 150 hp. then in 99 they changed the v6s to 190 hp and they will run high 15s with 5 speed. i would say a guess on a NA 3.8 in a big Azz bird or cougar is a low or mid 17.
 
My rather old rx7 has a buzzer at 6500 at the tach redlines at 7000. But, since everything just spins, you can really wind them up as far as you want.
 
I believe...

If anyone takes a look at the their stock tachometer, you would see that the "official" redline occurs just short of 5500rpm. I would guesstimate that 5300rpm is the "official, from the factory, stock redline". Yes, it's possible to REV the engine beyond that printed line, and what XR7 dave is talking about is a fuel cut-off to save the engine, which occurs at the higher RPM.

Certainly with proper engine parts that are stronger and lighter and much better balanced, the theoretical maximum rotating speed of the assembly increases. However, due to the breathing characteristics of our engines, along with the low-rpm nature of our superchargers, many of the highest HP SC's generate their peak output under 6000rpm.

Can the 3.8L be built to rev to 8000rpm? Certianly. I've seen many OHV engines built this way. Can it do it using a Roots supercharger? Not really.

Wankels do not use a "crankshaft" per se. They use an "eccentric" shaft for the Trilobate (triangle thingy) to rotate on. I've seen a dissassembled Wankel engine and the eccentric shaft is very small and light. It really looks like a shaft from a 2-cylinder engine used in a garden tractor. So it's no wonder why it has a 10,000rpm redline.

Hondas: Because all of the engines are N/A ones, to induct the neccessary amount of air into those engines to generate the HP, you require higher RPMS. Honda engines are built to rev high and have a higher specific output. But within a very narrow engine operating window. Thats why a system like VTEC and VTEC-i, allows honda engines to be very streetable and broaden the RPM range.
 
Yeah all this talk of peak horse power and dyno evaluations is cool....

But the fact of the matter is for your speed to keep going up your RPMs also needs to be going you . If you going to achieve High top speed on the street you have wind it up through the redline in 1 gear and get the car moving as fast as you can .. So when it shifts or you shift and the RPMs fall back too 4200rpm where the motor makes most the power then you have to rap out the 2nd gear and get going as fast as you can in that gear.I seen guys run there 1st gear all the way to 50mph no problem. The more you rap a gear out the better your times will be. Cause you will be that much further down the track before you shift...
 
You're right...sorta.

Yes, reving up to max before you upshift will drop you into the thick of an engine's HP peak.

But your arguement is more a matter of proper gear spacing to match the power production characteristics of the engine.

With a broad torque curve of our engines, it isn't as crucial to keep the revs in a narrow band of engine RPM. With a small honda engine, it is.

Take the Honda S2000 engine for example. I don't know the specific numbers, but the gearing is tightly spaced to help keep the engine is the more powerful part of the rev range. Because the HP peak of the engine occurs just before redline (I think about 100rpm before redline to be exact), reving it to "redline" is beneficial. The gear spacing is short and the next upshift drops the RPMS down to about 7500rpm, which is close to the HP peak.

Our engines on the other hand generally make their HP peak around 4600rpm. Reving the engine beyond this can produce a lag in acceleration, than if one were to upshift at say 4700rpm.
 
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