[njb8199]

Re: At what RPM is engine damage a possibility? (24Hours)

Quote, originally posted by 24Hours »

Further, I'd like more info from Volvo on the block cracking problems they've had w/ the R's engine. Afterall, this engine started life as a 2.3ltr.

I don't know if you will get information directly from Volvo but Todd Henderson of HEICO told me in an email some time back that this is becoming a more prevalent issue, especially with modded R engines.

 

[RearWheelPaul]

Re: At what RPM is engine damage a possibility? (njb8199)

Not surprising, given that it is an open-deck design that lacks a full water jacket around the bores...

 

[KeystoneVolvo]

Re: (Warpedcow)

Quote, originally posted by Warpedcow »

They only need to last for two races.

True but his question was HOW does an F1 engine reach 20,000 rpm?

http://en.wikipedia.org/wiki/Formula_One_engines

Here are some extra tidbits about F1 engines:

The engine runs on fuel based on an EU standard unleaded that will be used by road car in 2005.The fuel burns at a very high temperature and has a fuel consumption of approximately 5 miles to the gallon. In addition, the engine uses specially formulated oil that is almost as thin as water to help reduce resistance. The efficiency of the oil allows the engine to run at a cooler temperature, which increases the aerodynamic efficiency of the whole car.

Few facts about Formula 1 engines:

Number of combustions in a GP: 8 million
Number of engine & vehicle measurements/second at top speed: 150,000
Maximum rpm: 19,000+
Number of individual parts: 5,000 approx
Number of different parts: 1,000 approx
Maximum exhaust temperature (in a race): 800 Celsius
Number of litres of air aspirated in 1 second at top speed: 450
F1 engines built in a year: 200
Weight in kg: <100
Engine assembly hours: 80
Hours checking a new cylinder head with computer tomography: 20

Yannis

 

[steamboatsig]

Re: (KeystoneVolvo)

I have also read that the F1 engineers have factored in the amount titanium stretches when acted upon by forces encountered at those RPM's.

 

[kenhoeve]

Re: At what RPM is engine damage a possibility? (RearWheelPaul)

Quote, originally posted by RearWheelPaul »

Not surprising, given that it is an open-deck design that lacks a full water jacket around the bores...

holy crap- translation for the peanut gallery pretty please.

all I know is the I5 has a nasty harmonic at high rpm's, and stock sleeves aren't good enough.

 

[Johann]

Re: (steamboatsig)

Quote, originally posted by steamboatsig »

I have also read that the F1 engineers have factored in the amount titanium stretches when acted upon by forces encountered at those RPM's.

This is with every engine. On road going engine's the general rule of thumb is to keep the squish distance larger than 0.040" else the pistons might hit the head. With the heat and speed the rotating parts will grow. On an R engine this distance is near 0.060".

 

[RearWheelPaul]

Re: At what RPM is engine damage a possibility? (kenhoeve)

Quote, originally posted by kenhoeve »

translation for the peanut gallery pretty please.

In order to make the engine short enough to package transversely, the block was designed without a full water jacket around each bore (i.e. not 360 degrees). Such designs are prone to hot-spots. This is the price of compact packaging.

To meet weight requirements, the block is of open-deck design. If you take off the head, you would be able to see down into the water jacket. This makes the block light, but has an impact on stiffness.

None of this is to say that the I5 is poorly designed. It's design is as good as can be expected given the basic layout (I5 = imbalance) and size/weight constraints. That said, I'd trust that Volvo engineers took this into consideration when establishing rev and torque limits. In other words, don't push the engine beyond its designed limits or it will cost you...

 

[TH@HEICO SPORTIV NA]

Re: At what RPM is engine damage a possibility? (RearWheelPaul)

Quote, originally posted by RearWheelPaul »

None of this is to say that the I5 is poorly designed. It's design is as good as can be expected given the basic layout (I5 = imbalance) and size/weight constraints. That said, I'd trust that Volvo engineers took this into consideration when establishing rev and torque limits. In other words, don't push the engine beyond its designed limits or it will cost you...

Amen...

(I'll say it...) "cost" can be another engineering consideration when making an open/closed deck decision...that's a factor here.

Open-deck is not the most wonderful idea when it comes to performance. The hot spot issue is a real one on R's.

Beating a dead horse, but everyone above who's brought up the shape of the power curve is correct...car is dumping fuel and cam/turbo configuration is such that anything above 5,500 rpm is swimming upstream. I'd get your foot out of it far sooner than you have been...you're not making any more power at 7000rpm than you are earlier in the rpm band, but you are putting A LOT of stress on the engine.

 

[AthruC]

Re: At what RPM is engine damage a possibility? (TH@HEICO SPORTIV NA)

I thought that engine RPM also had to do with how fast the valves can "return" to their position at rest. If the valve spring is too soft, the engine can start revving so fast that the crank goes through enough of a rotation to slam the piston into that valve that otherwise would have been closed - or does this just pertain to "money shifts"??

Also, as mentioned, you need to look at the amount of power the wheels are getting at (arbitrary numbers for argument's sake) 2nd gear, 7300 RMP (61MP) vs 3rd gear, 3600RMP where the power curve is in your favor. The only reason I could think of to stretch the rev range on a turbocharged car that runs out of breath at high RMP is to make a trap speed. Fortunately, the 6MT tops 2nd gear at 60MPH before the stock limiter tells you "no more," but if it were, let's say, 57MP, I could possibly justify the higher limit.

 

[TH@HEICO SPORTIV NA]

Re: At what RPM is engine damage a possibility? (AthruC)

Quote, originally posted by AthruC »

I thought that engine RPM also had to do with how fast the valves can "return" to their position at rest. .

'Valve float' can be a legit high-performance issue more generally, but not one that I'd worry about on the R's...this is way down the 'worry' list, IMO. I don't think (without missing a shift) it's possible to 'float' the valves on the R in normal acceleration, but I could be mistaken. Could be happening as low as 7,000 rpm, but I wouldn't think so until up in the 9-10,000rpm range.

Float tends to occur at very high rpm...F1 cars do without traditional valve springs for this reason...IndyCar/CHAMP Car/IRL etc are pushing right up against the mechanical limit of what mechanical valve springs can do.

The hot spot issue is a much bigger thing to worry about, in our experience...valve float may be happening, but this is generally not as big an issue as it might be on very high-revving normally aspirated engine where compression ratios are very very high (missed shifts on the lasts generation M3 were quite common due to the gate configuration...and missing a shift can damage the piston crowns on those engines due to the zero-clearance head).

Miss a shift and that's another story, but I am not aware of float being a big issue under normal acceleration on R's. It's all 'bad' up there...car is shutting down for a series of reasons. Not precisely sure why there isn't a soft-limiter in there at around 6200, but such is life.

 

[Warpedcow]

Re: At what RPM is engine damage a possibility? (AthruC)

Quote, originally posted by AthruC »

Also, as mentioned, you need to look at the amount of power the wheels are getting at (arbitrary numbers for argument's sake) 2nd gear at 7300 RPM vs 3rd gear at 3600RPM where the power curve is in your favor.

There's more than that too. If you're shifting sooner, you're travelling slower for those few tenths of a seconds where you're coasting. If you shift later, you're travelling faster during the shift, which provides an advantage as well.

I've played around with this sort of thing A LOT on Forza 2, with all of the cars in the game. Despite the HP falling off quite a lot in many of those cars in the game, it is still fastest to shift at the absolute red line. The only exceptions are the Peugeot 908 and Audi R10 diesel Le Mans cars, which fall from a peak of approx 900 lbft of torque to 550 lbft or so at red line. The R has nowhere near as big of a drop.

I also have some real-world data to support this. As you can see in my sig, I have very accurate G2X telemetry from both of my Volvos at BIR. As it turns out, the 3-4 straight at BIR was just right for 3rd gear with the T5's 5spd manual. It is too long
for the R's 6spd manual (I need 4th for a bit if I get a good run out of turn 3). I experimented a LOT with shifting at different RPM along this section of track. The data support my theory that shifting higher is better (as long as you don't hit the limiter). If you want me to post some graphs, I will.

I would thus state that if being as fast as possible is your only concern, shift the R at as high of an RPM as you can without kicking in the soft rev limiter.

 

[JRL]

Re: At what RPM is engine damage a possibility? (Warpedcow)

Quote, originally posted by Warpedcow »

I've played around with this sort of thing A LOT on Forza 2, with all of the cars in the game. Despite the HP falling off quite a lot in many of those cars in the game, it is still fastest to shift at the absolute red line. .

Try the real world, it isn't in most cars
Now, if you're at a track and you are close to red line just before the braking point, absolutely, but if you're not, no

 

[FEO]

Re: At what RPM is engine damage a possibility? (Warpedcow)

I think the original poster is more interested in chirping tires in 3rd and 'butt dyno' measurements than increasing average speed around a given track. Therefore the answer should be 'shift before 5K if you want to see youR engine grow older'.

The question I would add is, can he theoretically still chirp tires in third gear shifting @5k? plenty of people have said 'you are not generating any more power'....is he generating more of something else (besides heat)? isn't the transmission gearing somehow involved in this process?(torque to the wheels,etc)

BTW very instructive thread, thanks all

 

[RearWheelPaul]

Re: At what RPM is engine damage a possibility? (Warpedcow)

The best strategy for shifting depends on the manner in which the car generates torque. It is best to shift at an engine speed that corresponds to the greatest area under the torque curve. Sometimes this equates to a shift at the redline, at other times it does not.

Finding an optimal shift point requires:

a. gear (all gears) and final drive ratios; and
b. the torque curve of the engine, calibrated according to engine rpm.

 

[TGO]

Re: At what RPM is engine damage a possibility? (RearWheelPaul)

Quote, originally posted by RearWheelPaul »

In other words, don't push the engine beyond its designed limits or it will cost you...

so what would you consider pushing it?

 

[RearWheelPaul]

Re: At what RPM is engine damage a possibility? (TGO)

Beyond designed limits =

- exceeding red line (never/never do this unless you've completely torn down the engine, installed upgraded rods, HD valve springs, and precision balanced all rotating components);

- removing low gear torque limits (this may be done, but only/only if accompanied by durability mods such as a thermostatically controlled aux transmission oil cooler, regular fluid changes using Volvo specified fluid, upgraded angle gear bolts, periodic angle gear inspections);

- slightly increased boost (~1-5psig), using an upgraded ECU (never/never do this unless the ECU's boost setting is compared against the turbo's compressor map, installed along with an upgraded engine oil cooler, and accompanied by a mandatory switch to synthetic lubricants. Note: I would recommend a HD intercooler, not water injection).

Even after all these precautions are taken, the best one is likely to achieve is *near* stock reliability.

 

[TGO]

so an exhaust/dp/ecu is pushing it then??? that sucks

 

[RearWheelPaul]

Re: (TGO)

Without any mods to mitigate the added thermal load and mechanical stress, you're trading durability and reliability for power.

Additional power is easy. Additional power + durability is much more difficult. Reliable power is achievable, but one has to open their wallet just a little bit wider...

 

[njb8199]

Re: (TGO)

Quote, originally posted by TGO »

so an exhaust/dp/ecu is pushing it then??? that sucks

Yes.

Ask Todd Henderson about how many R engines have blown in Europe.

Then search the archives for blown R engines.

If you modulate your driving and focus on low end power, especially torque, you'll be fine but if you drive your modded R like the Dukes of Hazzard, then you're asking for it.

Why do you think the aftermarket tuners (RUF, AMG, RennTECH, Hammann, Dinan, etc.) balance each engine and its components individually? It is to prevent this sort of occurrence.

 

[TGO]

i don't drive like that. and i've read about extended runs at WOT being an issue.

i would also get an intercooler since it just makes sense...and i already use GC oil, is there a better oil cooler available??