620R engine cutout at high G

[Mario149]

Just been driving my 620R at The Supercar Event this weekend and noticed that on one of the faster corners where there's a lot of lateral G, the engine was losing power. Seemed to only happen when the fuel was below 1/4 tank level. Presumably just fuel starvation?

[GreigM]

Yes, exactly that.

[lexham]

Was this yours?
We saw this frankly crazy thing on a few of the runs and it really is just amazing. My 6 year old thought it was hilarious at how fast it took off and monstered up to and past pretty much everything.

Sounded great too!

Edited by lexham on Sunday 3rd July 20:28

[DCL]

Left hand bends need a bit more fuel as the pump and pickup are on the left of the tank. I found, with standard tank, 15-20L was about as low as you can safely go on anticlockwise circuit, or track with repeated left turns.

[Mario149]

lexham said:

Was this yours?
We saw this frankly crazy thing on a few of the runs and it really is just amazing. My 6 year old thought it was hilarious at how fast it took off and monstered up to and past pretty much everything.

Sounded great too!

Edited by lexham on Sunday 3rd July 20:28

Nope that was the caterham company chap, he seemed to be taking it a little easy I was in the one below, I left my windscreen on so people didn't have to wear a helmet if they didn't want to. Weekend has been *awesome*. Wet track today even more so, luckily I swapped my ZZRs for my wet option ZZSs the other day, saw the photographers at Gambon egging me on to give it some oppo so happily obliged looking for pics/vids of my car on track if anyone has any

[Mario149]

DCL said:

Left hand bends need a bit more fuel as the pump and pickup are on the left of the tank. I found, with standard tank, 15-20L was about as low as you can safely go on anticlockwise circuit, or track with repeated left turns.

Yeah, that makes sense, corner I had probs with was a left hander.

[fergus]

Surprised that the 620 does not have a swirl pot/baffling built into the tank to avoid this?

[jontysafe]

Looking at he exhaust of the first pic exhaust gas temps look very high on that car.

[GreigM]

jontysafe said:

Looking at he exhaust of the first pic exhaust gas temps look very high on that car.

Its the flatshift on the 620R, sends unburnt fuel down into the exhaust which goes bang in that silencer.

[GreigM]

Mario149 said:

Mario, I notice you have taken off the number plate and have no blanking - how are your temps? I've left the front plate on to partially block out the oil cooler as the oil temperature stays way too low without. I also usually run some level of blanking on the water rad to try and bring all the temps up quicker - only on the absolute warmest of summer days have I found no blanking is necessary.

[Mario149]

GreigM said:

Mario149 said:

Mario, I notice you have taken off the number plate and have no blanking - how are your temps? I've left the front plate on to partially block out the oil cooler as the oil temperature stays way too low without. I also usually run some level of blanking on the water rad to try and bring all the temps up quicker - only on the absolute warmest of summer days have I found no blanking is necessary.

Honestly, I've kind of given up faffing with blanking. I had duck tape covering almost all of the front grill at one point, and depending on external temp I was peeling it off or adding more. No matter what I do though, normal driving water temp is almost always low, oil pressure is always high and flicking in and out of the red zone.

At TSE, the car was always fully up to temp before going out due to idling in the queue, and when thrashing it it seemed to stay okay.

[thebraketester]

Apparently its an unfixable problem... Ill buy the car off you for 5000 quid just to make it easy and painless for you?

[Mario149]

thebraketester said:

Apparently its an unfixable problem... Ill buy the car off you for 5000 quid just to make it easy and painless for you?

That's very generous, I'll bear it in mind

[battered]

fergus said:

Surprised that the 620 does not have a swirl pot/baffling built into the tank to avoid this?

Exactly this, the injection tank does indeed have a swirl pot built in. I know the 620 will rip through the fuel but the swirl pot should cope for the duration of the corner and then be refilled by the feed pump. Is there a possibility that your fuel pump is on the way out?

[Mario149]

battered said:

fergus said:

Surprised that the 620 does not have a swirl pot/baffling built into the tank to avoid this?

Exactly this, the injection tank does indeed have a swirl pot built in. I know the 620 will rip through the fuel but the swirl pot should cope for the duration of the corner and then be refilled by the feed pump. Is there a possibility that your fuel pump is on the way out?

No idea tbh. The corner the cutout was happening on was quite a long one and toward the end of it, and only a few secs after a prev quite long left hander as well - essentially they're both almost one long corner to a greater or lesser extent. Suppose it could be that the pump was struggling to get fuel into the injection tank at the start of the first and then towards the end of the second the injection tank would run dry? Bear in mind this was happening when I only had a few litres left in the tank and the gauge was showing 1/8 full or so.

[battered]

If this is the case then the whole affair is badly designed. It wouldn't be the first time for a Caterham product, TBH.

[Mario149]

Personally I just like to think I'm too hardcore for the car

[fergus]

battered said:

If this is the case then the whole affair is badly designed. It wouldn't be the first time for a Caterham product, TBH.

+1

The swirl pot should be fed by a pump which has a fairly high flow rate. Any excess will drain into the main tank anyway. If the swirl pot is running out of fuel, that is poor design/specification of parts...

An updated lift pump will probably sort that out (assuming the hiccup was related to fuel delivery).

[DCL]

The swirlpot in the tank is fed by a venturi scavenge device (orange bit in the photo) from the pressure relief/return (internal to the pump). The trouble is that with big BHP the return pressure can drop, and scavenge drops off too. Basically the fuel pump is not designed for motor sport.

[craig2003]

Mario149 said:

GreigM said:

Mario149 said:

Mario, I notice you have taken off the number plate and have no blanking - how are your temps? I've left the front plate on to partially block out the oil cooler as the oil temperature stays way too low without. I also usually run some level of blanking on the water rad to try and bring all the temps up quicker - only on the absolute warmest of summer days have I found no blanking is necessary.

Honestly, I've kind of given up faffing with blanking. I had duck tape covering almost all of the front grill at one point, and depending on external temp I was peeling it off or adding more. No matter what I do though, normal driving water temp is almost always low, oil pressure is always high and flicking in and out of the red zone.

At TSE, the car was always fully up to temp before going out due to idling in the queue, and when thrashing it it seemed to stay okay.

I have noticed the oil pressure light flicking in and out of red when run on a cooler day. It was fine when warmed up in decent outside temps I seen last week in Europe. Will see how it goes with Scotland in Autumn.
What water temps are you usually running? Highest I have seen was a little over 80 with the heater off at low speeds.
Maybe I should add some blanking?