Running an F4R at WOT for 30 seconds?

[The Fatty]

Just having a conversation with someone at the moment about rolling roads, and they have told me its not safe to run an F4R at WOT (wide open throttle) for 30 seconds on a rolling road. I always thought it was fine to run WOT provided it wasn't at constant high revs (i.e 6Krpm+ for 30 seconds), which doesn't happen on a RR anyway. Sometimes I can be at WOT in gear 5 going up a hill for some time (obviously the revs are only about 3Krmp), is this also bad?!

Can someone educate me in this area please? thanks

 

[Addicted]

If it's on an RR then surely it has a fan or two blowing cold air onto it - so what's the issue?

Granted, you don't want to run it for hours, but I'm sure 30 seconds would be fine.

He's talking crap.

 

[Dan@SJM]

The airflow provided on the said rolling road isn't sufficient. Speak to any other rolling road operator and they'll say the same.

 

[Dan@SJM]

Also running it at 5th at 3krpm is fine as that's still 70mph air flow. When you're working a boosted engine at full throttle you want to see 100+mph air flow. The particular rolling road cell I use can exhange the full dyno air capacity every 4 seconds.

I'll add that when I was on my ecu looking at the data as it was running up I saw 45 degrees plus intake temps. Their cooling is not sufficient to run an engine at WOT for that long.

 

[The Fatty]

The airflow provided on the said rolling road isn't sufficient. Speak to any other rolling road operator and they'll say the same.

Not taling about yours Dan :smile: Its me and @Luke_Exc that's conversing this and he got me wondering when he mentioned it. Luke said 'the ring lands in an f4r are far too delicate to be under WOT for 30 seconds safely'? I dont understand 😧

 

[The Fatty]

Also just to clarify, were talking non-boosted normal F4R's.

 

[Dan@SJM]

Even so, it still needs a lot more air flow than the desk fan that Tipton provide. Engines work bloody hard at WOT, EGT's go up through the roof, and that's when ring lands start to say foxtrot oscar.

 

[The Fatty]

Even so, it still needs a lot more air flow than the desk fan that Tipton provide. Engines work bloody hard at WOT, EGT's go up through the roof, and that's when ring lands start to say foxtrot oscar.

So the risk isn't really to do with the mechanical side of F4R running at WOT for 30 seconds, its more to do with providing sufficient airflow to it, so it is working within its temperature limits?

So for example, I'm not causing any potential damage to my engine by driving it at WOT because the airflow is sufficient? So if the rolling road could simulate this then it wouldn't be a problem to run for 30 seconds?

 

[Addicted]

Exactly, the problem is heat, if you can get rid of the heat then there's no problem!

 

[The Fatty]

Also i'm guessing its relative to rpm, so a poorly cooled RR would only be at risk above a certain level. Take tipton as an example, whilst its reving up to say 5Krpm its all ok, but then the 5 or 10 second of so it take to go from 5K to 7K is the actual duration of risk? i.e its the last 5 or 10 seconds where things may get too hot, not the full 30 seconds?

This question is a bit unrelated to the thread, but it sort of leads on from the answers above; what size fan should one look for in a RR? pics would be nice

 

[warwickstingray]

Ford ran the humble CVH at full throttle for hours when testing the exhaust box material on the mk2 XR2 as it could be defeated at sustained high speed. They tested them for much longer than that before deciding on the turbo version's bearings. If you can keep the engine happy it'll be fine.

The time my XR2 spent at full throttle when I was young and stupid. Was with the benefit of the cool night air I might add. Dismantled that engine many times as I upgraded and found no issues. No where near as strong an engine as the F4R.

And only making about 60bhp per litre

 

[Dan@SJM]

Tiptons would be fine at 2000rpm and that's about it. If the engine coolant temp goes up on a run, quite simply it's not enough cooling.

Rstuning fan is big enough that it sucks the door closed on the office when it's switched on.

Here's badger 5's setup

 

[Martin.]

Very interesting thread to read. I've always wondered this.

How does SRR compare Dan?

Not heard of Tiptons though :blush:

 

[Dan@SJM]

Here's what a dyno ramp rate should be.

 

[Dan@SJM]

Very interesting thread to read. I've always wondered this.

How does SRR compare Dan?

Not heard of Tiptons though :blush:

Never been......

 

[The Fatty]

Is this fan better than Tiptons?

 

[warwickstingray]

Depends on the engines cooling ability as well. Some engines have little in reserve. My HDI on a stage 1 re-map has a heat exchanger between oil and coolant. It's useless above standard and actually makes things worse.

 

[The Fatty]

Here's what a dyno ramp rate should be.

That's boosted though? Chips turbo sounded like that at tiptons didn't it? So would a normal NA f4r still take about 30seconds on that one, or is the ramp rate adjustable?

chips for reference...

 

[Dan@SJM]

The difference is chips was wheel spin. Which meant the rollers were braking too hard.

Even mine running the supercharger was still at WOT for 36 seconds

 

[The Fatty]

The difference is chips was wheel spin. Which meant the rollers were braking too hard.

Even mine running the supercharger was still at WOT for 36 seconds

did anyone film that btw? I didnt see it as I was late

 

[The Fatty]

Regarding ramp rates, does a shorter ramp incur less accuracy than a longer ramp? thinking in terms of 'time to acquire'?

 

[Dan@SJM]

Not really, most are happy with self adjusting their ramp rate.

 

[Borstii]

WTF is going on with the passengers side wheel?

 

[The Fatty]

interesting. thanks for the info :up:

any opinions on that fan I posted above? here is it in action... still 30 second ramp, but is the ramp vs cooling better? Looks like a pretty big fan?

 

[Dan@SJM]

That was only 20 seconds. Fan, could be good but hard to tell without being there and judging the wind speed

 

[McGherkin]

WTF is going on with the passengers side wheel?

OZ F1 syndrome.

 

[Adey.]

badger 5s fan setup struggles after a day of mapping, used him a fair bit over the last few years as im on the same trading estate, when i had my LCR we ended up misting the cooler and inlet with water to try and keep temps down.

 

[Dan@SJM]

A day of mapping is somewhat different to a 15/20 second run. His are ample for a couple of power runs.

 

[Adey.]

yeah very true, so as long as the cooling is sufficient there is no issue?

 

[Dan@SJM]

I'd still not want 30 odd seconds of full throttle. 15/20 at most.