Audi R8 Forums banner
1 - 20 of 28 Posts

·
Registered
Joined
·
201 Posts
Discussion Starter · #1 ·
So what is the maximum safe rev limit on the 4.2v8 (stock) that people use? (Obviously once warmed up and while "spirited" road driving as opposed to racing!
Do they have a safe soft rev limiter (I imagine they must).
Just out of interest really having test driven a few and not having thrashed any to the top of their rev range that's all. They seem a very rev happy engine.
 

·
Registered
Joined
·
106 Posts

·
Registered
Joined
·
1,230 Posts
Like someone wrote before:

Redline is 8700. That doesn't mean the engine explodes at 8800. The rev limiter is designed to cut torque output so the engine/car won't accelerate past 8700. Since it's still pulling hard even at 8700, the reduction of torque from lots to net-zero feels abrupt. This is kind of unavoidable unless you want to allow it to overshoot past 8700.

Remember, this engine/ECU was designed by German engineers. They wouldn't code a rev limiter to prevent stress from overev, and then have there be damage when it operates.

There are a lot of rich knuckleheads out there with R8's too...just not on this board. If the engine was damaged by bouncing off the limiter, there'd be a lot of broken R8's out there.

There's always auto if you want it to upshift.

Although, strangely, it will downshift for you in manual non-sport, if you punch it.



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
612 Posts
If you shift from 5th to 2nd while at 5k rpm on the manual cars, is there still a limiter to stop an engine damaging over-rev event in that scenario ?

I know on manual Porsche there isn't any such protection, you need to factor in a check for engine over revs from the car's computer during any PPI.
 

·
Registered
Joined
·
28 Posts
If you shift from 5th to 2nd while at 5k rpm on the manual cars, is there still a limiter to stop an engine damaging over-rev event in that scenario ?

I know on manual Porsche there isn't any such protection, you need to factor in a check for engine over revs from the car's computer during any PPI.
A limiter can't do anything in that situation, as what you've described is a purely mechanical process. If you select a gear that would result in 10,000 rpm and engage the clutch, the engine will spin up to that speed. It's purely wheel speed, multiplied through a gearbox spinning the engine.

The only way a car could ever stop this would be to somehow physically lock-out gears at certain speeds to prevent you from selecting them. To my knowledge, no car or car maker in history has ever done this.
 

·
Premium Member
Joined
·
3,984 Posts
Just make it a point to be mindful of where the engine is in its rev range and work on shifting about 500 rpm or so before the limit. This is where the torque and hp start signing off so anything above that is "wasted", if you will.
 

·
Registered
Joined
·
5,112 Posts
8k + revs is going some, obviously a nicely balanced well engineered V8.
My last V8 was a 6 litre LS6 in a Lola T70 replica which was on a mild cam and only rev'd to 7200rpm
I did wonder if your username had anything to do with the awesome Lola T70. I bet you wish it was an original.
 

·
Registered
Joined
·
4 Posts
Just a quick point to make about gear ratios, don't forget that when you change up a gear, the torque to the wheels drops directly according to the gear ratio change. That's why high revving engines are the nuts, don't change up until the end-stop is almost there, you can be in a gear lower than a puffing wheezing turbo is.
 

·
Registered
Joined
·
5,112 Posts
Yes it would have been nice. Mine was a Gardner Douglas T70 spyder with circa 480-500bhp. Loved that car!
Sounds superb. What did you use it for? Be nice to see a couple of pictures too.
 

·
Registered
Joined
·
201 Posts
Discussion Starter · #14 ·
Sounds superb. What did you use it for? Be nice to see a couple of pictures too.
I can't get the junk that is photobucket to work to link my album but this is the Gardner Douglas site about their T70.
http://www.gdcars.com/cars/gd-t70-spyder/
It's basically a spaceframed chassis with bespoke alloy uprights, double wishbone suspension and an open ****pit. The gel coat body was moulded off the heritage Lola T70 panels so it's very close in terms of look but not a tub chassis. It's very very high quality as far as kit cars go, certainly better than an Ultima on track. It's built on any LS series or sbc engine using a porsche 6 speed box and is manual with no driver aids whatsoever. 900kg, huge brakes and 500bhp. I used mine for timed sprints and trackda6s but they are road legal if you register them
Great fun on track, not much quicker I found on trackdays other than radicals.
Rear tyres are 335-30-18s :)
 

·
Registered
Joined
·
5,112 Posts
I can't get the junk that is photobucket to work to link my album but this is the Gardner Douglas site about their T70.
http://www.gdcars.com/cars/gd-t70-spyder/
It's basically a spaceframed chassis with bespoke alloy uprights, double wishbone suspension and an open ****pit. The gel coat body was moulded off the heritage Lola T70 panels so it's very close in terms of look but not a tub chassis. It's very very high quality as far as kit cars go, certainly better than an Ultima on track. It's built on any LS series or sbc engine using a porsche 6 speed box and is manual with no driver aids whatsoever. 900kg, huge brakes and 500bhp. I used mine for timed sprints and trackda6s but they are road legal if you register them
Great fun on track, not much quicker I found on trackdays other than radicals.
Rear tyres are 335-30-18s :)
That is a thing of beauty and as you say, so close to an original in appearance. I can imagine it being a real blast on track. I've been sprinting for a good number of years, single seaters mainly but currently a 450 bhp Evo V1 RS.
 

·
Registered
Joined
·
28 Posts
Just make it a point to be mindful of where the engine is in its rev range and work on shifting about 500 rpm or so before the limit. This is where the torque and hp start signing off so anything above that is "wasted", if you will.
That's not really true, it's not wasted at all.

The power may tail off slightly compared to peak, but the power output just before the rev limiter is still way higher than the power you'll be at when you change gear.

The torque at the wheels, through the gearbox, will be much lower once you've changed up.

If you wanted maximum acceleration through the gears you'd change literally a split second before the limiter kicks in.
 

·
Registered
Joined
·
201 Posts
Discussion Starter · #17 ·
That is a thing of beauty and as you say, so close to an original in appearance. I can imagine it being a real blast on track. I've been sprinting for a good number of years, single seaters mainly but currently a 450 bhp Evo V1 RS.
Yes I enjoyed building it, and it was a life experience driving it hard for the first time.
This is a GDT70 going round the Ring in sub 8mins. I drove this car at Croft racetrack once it was an ls7 7 litre with about 650bhp in 900kg. The driver is an Italian racer (watch the video through and you'll appreciate his driving skills.)
The speedo bounces about a bit but the car was GPS verified at 176mph on the straight if I recall.
The way it goes past cars gives you an idea of the acceleration
Enjoy :)
https://youtu.be/4MZ3Rbhui7c
 

·
Registered
Joined
·
5,112 Posts
Very impressive and the driver is clearly very skilled. I'm not sure if I would want to pilot that around the ring with its lack of run-offs.
 

·
Registered
Joined
·
201 Posts
Discussion Starter · #19 ·
Very impressive and the driver is clearly very skilled. I'm not sure if I would want to pilot that around the ring with its lack of run-offs.
me neither, tbh its too much power in a mid engine lightweight car with no driver aids. the guy who actually built it crashed it at Cadwell Park first time on track and sold it soon after. mine was about perfect with 480-500bhp.

fingers crossed i will have my first R8 this time next month! :)
 
1 - 20 of 28 Posts
Top