HG blown on supercharged MPI
Turbo Mini Forums

I take it the pulley diameter and speed is a linear relationship? so if i want to slow it down by 25 -30% then i will need a pulley size of 65 x 1.3 = 84.5mm. Please correct me if im talking utter bollocks!

isn't it a linear relationship based on the cercumferance sp?

think of it in terms of teeth on gears,

Lets first of all work out why you are getting 18 psi with the standard blower pulley.

You need to measure the crank pulley, then we can work out the blower pulley size, otherwise you are guessing.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I've done some preliminary calcs on this.

You probably have a blower/engine ratio of 1.8:1 approx.

The sprintex calculator for the M45 suggests that this should give you 13psi. However, the sprintex calculator does not appear to take account of temperature rise due to the inefficiency of the blower at high boost levels.

If you allow for the density change due to the high outlet temperatures, then this will take the boost up to around 18psi.

The density change is outlet temp/inlet temp in Degrees K.

I think that you need to take the ratio down to about 1.5:1 this will bring the boost down to around 10psi.

The sprintex calculator is here:

http://www.sprintex.com.au/files/Blower_Calculator.xls

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Right chaps, just got the head off an i measured the crank pulley at the same time. I struggled to get my verynear on the pulley but i got it at 115mm which as gives me a ratio of 1.77:1 with the standard 65mm blower pulley.

I cant see any damage at all to the pistons but the centre 2 have much heavier deposits on than number 1 and 4. I take it this is probably whats left from the oil i tipped in to the bores in the couple of weeks before i started the engine.

The HG has gone between cylinder 4 and a waterway as expected. See attatched pics

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Stick an AF460 gasket on it

Some people have no problems with the BK450, while I have had them all. Swapped to the AF460 and i havent had an issue yet.

IMO

The gasket was an AF460 on inspection. I dont think it was torqued correctly as they seemed to crack undone a little to easily for my liking.

Is the fouling of the inner cylinders going to cause any probs??

Also how do i idenify omega pistons? The stamp on them is 3025.

Right just been on the sprintex page and by my calcs then i need about a 74mm pulley on the charger instead of the 65mm

Edited by Paul S on 11th Sep, 2008.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Fueling is by 2 injectors direct in to the vacuum side of the charger.

ECU is emerald K3 with an innovate wideband fitted. Dave Walker set it all up and its not using the adaptive mapping as he said the map is right and the adaptive would just be chasing its tail all the time.

Lambda is fitted in the y piece of the lcb

The gasket in the picture above is a BK450

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Hi,
That almost looks like something was trapped in the fire ring when it was bolted down (2nd pic)
Cheers,
Gavin :)

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Hi sprox the gasket is stamped with AF470 not AF460.

I know about the charge robbing but i take it that there is nothing i can do about it? as it already runs a 'wet' manifold set up?. Is it likely to cause any trouble?

As for the HG thats what i thought as there didnt look to be any specific damage to the firing ring but there was a little pile of corroded shit out of the head sitting on it. Maybe it wasnt cleaned out properly? or maybe it just came out when i lifted the head off? i guess i will never know?

Still need to find out what the pistons actually are, are they cast or forged and what dish is in them. All i know is that i asked and paid for the FIS ones and that the ones fitted are marked 3025.

what is the full writing on the piston at the waterpump end, number 1 piston.

The full script is Omega +20 and then the 3025

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Umm... how about detonation and blown head gaskets.

Good point, Im hoping i can get away from this though by dropping the boost and intake charge temp......god damn 5 port heads! If only an 8 or 7 port would allow the charger etc under a standard bonnet line

Its a BK450 with some extra copper rings around the smaller coolant passages