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is the revised 7k redline using the Cobb AP safe enough?

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#1
I was doing some datalogging the other day and it was then that I realized the stock 6300-6500 redline/fuel-cut off isn't there anymore (Thanks Cobb AP). It's now 7k. I'm sure everyone already knew this (sorry, I'm a noob). My question is: How much worse is it on the engine by raising it those ~500-700 rpms? Just curious.

I'm now wondering whether I'm beating on my FiST too much (less than 2500 miles on it and I'm taking it to a 7k redline one or two times/week.

Thanks in advance.
 


BoostBumps

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#2
I just reviewed all maps using COBB ATR...

The original Rev Limit (Fuel Cut) value entered for stock / OE setup is 6600rpm....All of Cobb's OTS maps raise this by 400rpm to 7000rpm

[HR][/HR]


"Rev Limiter (Fuel Cut)

This is the primary failsafe engine speed limiter used when the engine is running. Prior to this being used, the ECU will attempt to use all of the throttle cut based limiters. This limiter activates a fuel cut when in use."



Stock (Stage 0) Rev Limit Value

Stock REV Limit.jpg

Stg1 Rev Limit Value

Stg1 REV Limit.jpg
 


OP
O
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Thread Starter #3
I just reviewed all maps using COBB ATR...

The original Rev Limit (Fuel Cut) value entered for stock / OE setup is 6600rpm....All of Cobb's OTS maps raise this by 400rpm to 7000rpm


Thanks BoostBumps for the info but do you have any insight to safety, reliability or even to the 'why' of the increase of 400 rpms? I'm all for it, just wanted opinions. Thanks!
 


BoostBumps

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#4
Thanks BoostBumps for the info but do you have any insight to safety, reliability or even to the 'why' of the increase of 400 rpms? I'm all for it, just wanted opinions. Thanks!
I edited my post above to show actual REV Limits entered for Stage 0 (stock) and Stage 1 COBB maps...

COBB is fairly conservative with their tunes...As such I wouldn't think increasing rev limit by 400rpm would adversely effect safety or reliability but there is really no need to go there anyways...Personally its rare that I ever push my car past 6200rpm ...That said, I know there are some guys with BT's here on the forum who have pushed revs out to +7500rpm ...now is that safe or reliable? Only time will tell I suppose....
 


dyn085

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#5
Unless you upgrade the turbo there's not really any need to be that high in the rev-range to begin with, but DHM and other tuners have all said that the valvetrain is good to at least 7k (and some tune higher).
 


RAAMaudio

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#6
With a stock about the only thing you would have a need for 7k or higher redline is autocrossing and not having to shift to third or be on the rev limiter on some sections of the course.

Higher revs are much harder on the valve train but this car is pretty strong in that area so it does not seem to be an issue, nothing reported I know of at least.

Even on a big turbo car it is not always faster to hit the red line in each gear, sometimes it is better to shift earlier if the revs fall into a better place on the torque curve on some parts of a track or for those so inclined, canyon or mountain run...

For those that want to maximize every bit of power they can use it works out well to plot it all out using each gear ratio, time it takes to shift, dyno plot, etc and see where the revs fall into the best place, shifting up or down depending on the use.
 


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#7
I have my fuel-cut limit set to 7500 rpm. Not because there is any power out that far with a stock turbo, but to allow other functions to work much better. Like mentioned earlier it helps in autocross to save a shift on a particularly long section plus it results in ZERO lag when I FFS at 6 to 6500 rpm in a pure acceleration event like a drag race or even rolling side-by-side race.
 


OP
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Thread Starter #8
Very much appreciate the responses. I feel like I've learned something today.

I often miss the old Honda days of 8k redlines. The sound of the motor at 7900 RPMS is like music to the ears.
 


RAAMaudio

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#9
Mine is at 7300 and I used it for some rather serious canyon climbing stuff(staying in my own lane and not at the edge of grip in the turns as not safe on public roads, as fast as my car is even more so) I have lots of lag on the bottom end so it really helps having the high rev limit and I make power there as well. That also makes it far trickier to drive well so I am going to a smaller turbo to widen the power band. Right now the car is like Jeckle and Hyde, mellow or nuts and I want to be able to just have a spirited run at more moderate paces as I save anything serious for a race track.

The little engine sounds pretty dang sweet at 7,300, sure it would be very fine at 8k which may happen at some point, right now the hard limit is at 7,700 in the ECU.
 


frankiefiesta

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#10
Very much appreciate the responses. I feel like I've learned something today.

I often miss the old Honda days of 8k redlines. The sound of the motor at 7900 RPMS is like music to the ears.
i had my old 07 civic si tuned with a 8500 redline. Loved the sound and high revs, hated not having any torque
 


Sourskittle

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#11
I hated valve guide seal changes on Vtak hondas too, lol. All that rpm gets to the valve train sooner or later, even on a Honda.
 


Sekred

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#12
OxfordST does raise an interesting question.
If you look at Inertial load in a engine and the way it increases verse RPM, things can start to look worrying when you raise the redline. The increase in the inertial load factor is not linear verse RPM. For every 1% increase in RPM, inertial load increases by 4.
So increasing the redline from 6500rpm to 7000rpm raises inertial load by around 30%. Increasing it from 6500rpm to 7500rpm raises inertial load by around 60%.
You can see why revs kill engines.
I am not an engineer, these figures are from a texted book so feel free to correct me if you thing the info is incorrect.
 


RAAMaudio

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#13
I bought a forged LS1 from a race team that was built to spin to 7,800 RPM but rev limited in the race class it was built for to 6,500 where it still made close to 500 on 91 octane at the crank, at 7,800 it should of made around 600. By overbuilding the whole engine, not just the valve train, it would last a full race season against other teams engines built to handle 6,500 and last a few races that cost about 1/2 the price to build but more prone to coming apart during a race. I never ran that engine but have had LS2 and LS6 over 7,000 and they sound incredible, not at all like a small block Chevy, much more refined.
 


RAAMaudio

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#14
Great post, shows why they went away from 19,000 RPM F1 engines that cost a fortune and originally built to last one race!
 


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