Caterham 620R / 620S engine and fuel query.

Caterham 620R / 620S engine and fuel query.

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Discussion

Leejay-B

Original Poster:

93 posts

182 months

Monday 17th April 2017
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I am after some help please with trying to find info on the supercharged 620 engine. Does anyone know who designed and built the engine?

Also a main concern is regarding the ecu mapping and fuel RON? Recently an online handbook released shows 620 needs 98 Ron fuel.

My personal opinion is why take the risk, may as well use 98 Ron...

But what if you didn't? The dealer is saying the car is mapped on 95 Ron and so no issue. But that conflicts with handbook even though someone from technical department confirms 95 Ron is safe even with hard use. Also they said the engine has no knock sensor so they couldn't map on high Ron fuel, as it can't detect anything lower grade. I can't imagine there would be no knock sensor on an engine in 2017? Knock / pre detonation is a worry.

Thanks.

Ps I have emailed caterham themselves, but I won't know that the correct people will get involved.

Order66

6,726 posts

248 months

Monday 17th April 2017
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You should seek out " mic" on this forum, I believe he is responsible for the engine.

I've used mine exclusively on 98 - never had an issue, why not just run on 98 when that's what the book says.

GarageQueen

2,295 posts

245 months

Monday 17th April 2017
quotequote all
I asked Caterham, 95 is ok

the question I have is whether it will take high ethanol blend fuel (i.e E25)

Leejay-B

Original Poster:

93 posts

182 months

Monday 17th April 2017
quotequote all
Order66 said:
You should seek out " mic" on this forum, I believe he is responsible for the engine.

I've used mine exclusively on 98 - never had an issue, why not just run on 98 when that's what the book says.
Thanks I will message him.

It's not my car, but I agree for the sake of any risk just run on 98 to be 100%.

Leejay-B

Original Poster:

93 posts

182 months

Monday 17th April 2017
quotequote all
GarageQueen said:
I asked Caterham, 95 is ok

the question I have is whether it will take high ethanol blend fuel (i.e E25)
Same answer from Caterham then.

I will let you all know the email response as well.

Ethanol blend, isn't that popular with tuners in America? Don't they need Remaps to suit?

DCL

1,215 posts

178 months

Tuesday 18th April 2017
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I'd be interested in Mic's comments but it is normal for tuned Duratecs to have the Knock sensor removed as they are not useful for the higher RPM they are mapped for. Nor can I recall the MBE being able to use one (but might be wrong there). The 620 engine will almost certainly use a lower CR and able to deal will all fuels where Knock is most likely to happen. At the higher RPMs it will be mapped to use their chosen CR, boost, and fuel - most likely 95 Ron as there's little to be gained, and a lot at risk, to use only higher octane fuels.

Edited by DCL on Tuesday 18th April 10:41

Leejay-B

Original Poster:

93 posts

182 months

Wednesday 19th April 2017
quotequote all
Mic has replied by email, he has not had time for full reply yet but he did confirm mapping was 95 Ron.

Caterham also emailed me and confirmed the same thing. They also mentioned the lower compression ratio.
Caterham themselves did also say while it's mapped on 95 Ron that running higher Ron is needed for full quoted power.
I don't understand how that would work. If it's mapped on 95 have they also written in to the map to recognise better fuel and adjust timing etc to suit? Wouldn't that need knock sensors?

I thought engines could only recognise poor fuel and back off, and then keep testing for better fuel?

Leejay-B

Original Poster:

93 posts

182 months

Wednesday 19th April 2017
quotequote all
PS. This is just a forum. I don't want this thread to be the cause of issues so the handbook should be assumed correct unless you make your own enquiries direct to Caterham cars.

DCL

1,215 posts

178 months

Wednesday 19th April 2017
quotequote all
Knock sensors are usually used to allow the engine ignition to be advanced safely with a lean mix and provide fuel efficiency and low emissions. On a single vehicle approved car, this is not so important and you can map for maximum power and this will provide a margin. So, putting it simply, the higher octane [edit to say 'quality' is probably a better word than octane - but most high octane fuels are better quality, and of higher calorific value] fuel you put in, the more power you tend to get out.



Edited by DCL on Wednesday 19th April 21:20

Leejay-B

Original Poster:

93 posts

182 months

Sunday 30th April 2017
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I don't fully understand how you map with a margin.
In this case the car is mapped on 95 so how does the ECU provide more power when fuel is better?

DCL

1,215 posts

178 months

Sunday 30th April 2017
quotequote all
You are basically tuning for maximum power (ie with the optimum ignition) and then making it rich enough to prevent knocking on lower grade fuels. Basically you are using fuel to cool the combustion rather than retarding the ignition. The power is then related to how well, and how much of, the fuel burns, and that is down to the quality of the fuel.

Edited by DCL on Sunday 30th April 11:13

KN02LEY

72 posts

118 months

Sunday 30th April 2017
quotequote all
I'm pretty sure that petrol with a higher octane number doesn't have a higher calorific value. All grades of petrol are much the same, irrespective of the oilcos' marketing.

DCL

1,215 posts

178 months

Sunday 30th April 2017
quotequote all
KN02LEY said:
I'm pretty sure that petrol with a higher octane number doesn't have a higher calorific value. All grades of petrol are much the same, irrespective of the oilcos' marketing.
Agreed from a technical point of view, but why have high octane fuels? They basically allow you to run higher CR and extract more energy as the thermal efficiency is better. Advancing the ignition has a similar effect. Using a rich mixture, to keep the charge cool, allows you to up the CR and advance ignition (within limits) with a lower octane fuel. However when you put a higher octane fuel in that is better suited to the state of tune, the combustion is more complete and more power is released. But is not fuel efficient, so modern production engines don't do it.

Order66

6,726 posts

248 months

Sunday 30th April 2017
quotequote all
KN02LEY said:
I'm pretty sure that petrol with a higher octane number doesn't have a higher calorific value.
Correct, but that doesn't mean you can't extract more of the available energy from the fuel and that is what the higher octane allows. See DCLs post above.

KN02LEY

72 posts

118 months

Sunday 30th April 2017
quotequote all
I'm not disagreeing with DCL's general explanation, just the bit in last Wednesday's post which stated the higher calorific value error.

Advancing the ignition timing can help raise the mean effective pressure but then you can be helped by using petrol with a higher star rating (which has a shorter delay between the spark passing and the resulting pressure rise).

DCL

1,215 posts

178 months

Sunday 30th April 2017
quotequote all
What I was hinting at was fuels with a high ethanol content have a lower calorific value. Ethanol is around 30% less than petrol and when it is mixed with petrol at 10% (E10) then the overall reduction in power is around 3%. Buying a good quality branded high octane fuel usually means a lower ethanol content (as it is their premium product) and that means more power (more MPG). This is a relatively new phenomenon that coincides with the introduction of bio fuels and green ideas, but sometimes the traditional views about 'stars' and energy content still live on.

However, that's a side issue to mapping for a particular octane grade of fuel.

KN02LEY

72 posts

118 months

Sunday 30th April 2017
quotequote all
Agreed on all accounts :-)