The V8 Owners Forum -

Sounds like a sensible plan

Got some results of monitoring the intake temps.

The readings are taken post supercharger about 6" from the plenum. Ambient temperature 20c

Steady driving around 1500-2000rpm 36c
Large A road 2500rpm temps go up to 41c
Motorway 3000rpm up to 46c
country road so lots of on off throttle circa 40c
Stuck in very slow traffic lots of stop start 45c
Booting it temps rise dramatically once over about 52c the engine start pinking so definatley heat related.

The thing that surprised me was the lack of cooling at higher speeds. I realise with a supercharger the faster the engine is rotating the more the charger is compressing the air whether it's using it or not and the more the air is being compressed the hotter it will get but surly the intercooler should at least offset this increase. So is it likely I have an intercooler problem?
Cheers Chris

gilps wrote:Got some results of monitoring the intake temps.

The readings are taken post supercharger about 6" from the plenum. Ambient temperature 20c

Steady driving around 1500-2000rpm 36c
Large A road 2500rpm temps go up to 41c
Motorway 3000rpm up to 46c
country road so lots of on off throttle circa 40c
Stuck in very slow traffic lots of stop start 45c
Booting it temps rise dramatically once over about 52c the engine start pinking so definatley heat related.

The thing that surprised me was the lack of cooling at higher speeds. I realise with a supercharger the faster the engine is rotating the more the charger is compressing the air whether it's using it or not and the more the air is being compressed the hotter it will get but surly the intercooler should at least offset this increase. So is it likely I have an intercooler problem?
Cheers Chris

Pretty high for such low boost.

What is the IC, size, location, airflow ? What blower ? If it was very small it could still be heating the air a lot despite the low boost.

Either way, if tuned correctly, you should be able to avoid the detonation. Try the better fuel, have it pull some timing in those areas, and/or at those temperatures and see if that helps.

And look into a better intercooler.

If you can, go for a Garrett core, they really are superb. If you have room for a big unit, then slightly less need for quality, as it can be made up with in size.

In my opinion your burning temperature gets to hot by heat soak causing the detonation.
Been there, done that, melted a few psitons. Mixture was good, IAT was way to high at that moment causing way over the top combustionchamber temperatures.

Have you considered going the water/methanol injection route. Water and methanol cools the mixture down as it detracts heat when it evaporates.

Methanol raises octane also and is an extra amount of fuel when needed under boost conditions.

6 psi boost wont need high octane fuel. I am running my 9 to 1 Cr with 10 psi boost on 95 octane and a FuelCat for years. Must say, FuelCat does ad a few octane.

Do have added a Water/Methanol injection kit on it that kicks in at 4 psi. I added that kit to get the heat soak out of my roots blower as I had issues with it after driving 500 miles from Holland to the UK ending up in the famous traffic delays teh Uk has.

Have you tried Tesco for high octane stuff?
Said to be 99 octane

Ian

JP. wrote:In my opinion your burning temperature gets to hot by heat soak causing the detonation.
Been there, done that, melted a few psitons. Mixture was good, IAT was way to high at that moment causing way over the top combustionchamber temperatures.

Have you considered going the water/methanol injection route. Water and methanol cools the mixture down as it detracts heat when it evaporates.

Methanol raises octane also and is an extra amount of fuel when needed under boost conditions.

6 psi boost wont need high octane fuel. I am running my 9 to 1 Cr with 10 psi boost on 95 octane and a FuelCat for years. Must say, FuelCat does ad a few octane.

Do have added a Water/Methanol injection kit on it that kicks in at 4 psi. I added that kit to get the heat soak out of my roots blower as I had issues with it after driving 500 miles from Holland to the UK ending up in the famous traffic delays teh Uk has.

I think this is possibly the way to go in the long run. Under bonnet temps are a massive issue with Tvrs even without a blower. The engine is producing around 400 to 430 bhp with similar amounts of torque. ideally putting lots of vents in the bonnet would help a lot but but that would spoil the looks of the car and not a route I want to go down. I am looking at better ways to direct the air flow through the intercooler and then out of the of the under bonnet area, would running cooler plugs make much difference? think its on 7s at the moment

I don't have any det issues and my under bonnet temps are high too
mine was 12psi of boost and running through an intercooler,

For information; from one of my logs of my 4.6 supercharged (centrifugal) intercooled engine in my Dax Rush (very small frontal area so only room for a smallish intercooler - although do have flared side panels);
6.5psi boost at 4744 rpm
72% throttle
max incoming air temps of 29degC.
On a 20degC summer day.
AFR around 11.8,
Coolant a constant 85degC,
spark advance backed off to 26.
GPS speed 53mph

Tom.

gilps wrote:Got some results of monitoring the intake temps.

The readings are taken post supercharger about 6" from the plenum. Ambient temperature 20c

Steady driving around 1500-2000rpm 36c
Large A road 2500rpm temps go up to 41c
Motorway 3000rpm up to 46c
country road so lots of on off throttle circa 40c
Stuck in very slow traffic lots of stop start 45c
Booting it temps rise dramatically once over about 52c the engine start pinking so definatley heat related.

The thing that surprised me was the lack of cooling at higher speeds. I realise with a supercharger the faster the engine is rotating the more the charger is compressing the air whether it's using it or not and the more the air is being compressed the hotter it will get but surly the intercooler should at least offset this increase. So is it likely I have an intercooler problem?
Cheers Chris

Ok so if you had an engine in a Range Rover or similar and were driving in Saudi, UAE or similar on a hot day the inlet air temp with no blower would be up at that level. So realistically is it that high as to make a difference?

Ian