19 replies to this topic

[mighty_mini]

I was cleaning up a head i bought which visually you can see it has been heavily modified.

from what ive measured it seems to have had a slight skim also.

while cleaning it up i found some markings and wondered if this could be a genuine SWIFTUNE head. The bloke who i got it off, never said anything about which company did the tuning parts, but he did say that it had sent it to have alot of work done on it. This was also a turbocharged engine. The head also has been skimmed on top... is this for the roller tips, this head seems wierd

The plot thickens.......

Here is a pic, showing the SWIFTUNE stamp and 20 5 (but no decimal point present)

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[Jammy]

It will probably be worth giving Swiftune a ring, see what markings they usually put on their heads and where abouts they put them. But I would say if it has the Swiftune marking, chances are its Swiftune!

[Pavel]

Highly doubt someone else would bother putting swiftune on their own head lol

Pretty sure its a swiftune head, but ring em up and ask them about the figures. (20 5)

[Alburglar]

Well the stamps different to mine it shouldn't be offset like that and should be followed by numbers equal to it's caqpacity 1380 or 1293 etc, then a unique number which is longer than 3 three numbers. swifty can trace.
If not, then it's probably been stamped on by somebody to con someone at some point.

[Turbo Phil]

20 5 could be 20.5cc, the size of the chambers. Have you measured them ?
If they're only 20.5cc it doubtful it's been used on a large capacity Turbocharged motor, especially one running any real boost, as the compression would be far to high even with massively dished pistons.
It could also be what's skimmed off it ? 20thou on the bottom, 5thou on the top ?
Just a thought ........... :grin:

[mighty_mini]

spoke to swiftune earlier, and they said its def one of their heads, gone though what seems to have been done.

they are 20.5cc chambers with 5 thou off the top and manifold faces. we both had a good chuckle when i told him that the bloke was using it on a turbo. But as its modified already, its going to rich for the chambers to be opened up.

What kind of CC increase do you gain from removing the beak? i know its not the ideal solution to loose the beak but it'd be too good to waste a swiftune head i think

This is one for phil - what cc do i need to start to run higher boost? like 10-12psi?


cheers for the rsp

[Turbo Phil]

What size engine is it going on ? what cc pistons ? what head gasket ? how far are the pistons from the top of the block when at TDC ?
Give me these variables and i'll give you an idea of what to aim for.

[mighty_mini]

1275 with Morespeed turbo +040 - 10cc dish

BK450 Head Gasket

If i remember correctly the skirt was something around 20thou from the deck

once i have all the definate figures i will post up again. but was just looking for a ballpark figure so i dont overkill the head.


Cheers

Dave

[Turbo Phil]

Right had a quick weigh up. :wink:

To run 12psi i'd probably aim for a compresion ratio of about 8.5-1.

1275 with +040 rebore = 1312cc
Swept volume {v} = 328cc

Pistons = 10cc
BK450 headgasket = 2.8cc
If your piston to block height is indeed 20thou as you thought, then you've got 2.04cc here.
Ring land volume = 0.80 {rough estimate}
Head chambers = 28cc
So total volume above the piston {c} = 43.64

Compression Ratio.
{v} + {c} divided by {c} = 8.51-1 compression ratio with a 28cc head, 8.69-1 with a 27cc head and 9.07 with a 25cc one.

If the pistons come higher up the block or even flush then you're going to have to take a little more from the head.
Hope this helps.

Phil.

[Boab]

Right had a quick weigh up. :wink:

To run 12psi i'd probably aim for a compresion ratio of about 8.5-1.

1275 with +040 rebore = 1312cc
Swept volume {v} = 328cc

Pistons = 10cc
BK450 headgasket = 2.8cc
If your piston to block height is indeed 20thou as you thought, then you've got 2.04cc here.
Ring land volume = 0.80 {rough estimate}
Head chambers = 28cc
So total volume above the piston {c} = 43.64

Compression Ratio.
{v} + {c} divided by {c} = 8.51-1 compression ratio with a 28cc head, 8.69-1 with a 27cc head and 9.07 with a 25cc one.

If the pistons come higher up the block or even flush then you're going to have to take a little more from the head.
Hope this helps.

Phil.

The mind boggles

[wolfie]

boab did you buy that car from a pretty bird with a broad bristol accent lol

if so i did a fair bit of work to it

[Boab]

boab did you buy that car from a pretty bird with a broad bristol accent lol

if so i did a fair bit of work to it

Yes, look on page 2 of the 'to copy or not' thread and there is a pic of the beaut

[wolfie]

i know what laura looks like mate lol she stayed in my caravan at riviera run year before last

same year i put the steering rack on on put it though mot i think

[Boab]

i know what laura looks like mate lol she stayed in my caravan at riviera run year before last

same year i put the steering rack on on put it though mot i think

Lucky man :fear:

[Boab]

Okay Phil, what does all the above mean, and how do you measure the 'cc' that you mention.

I can see from the pic in Bluemini's thread that a chunk has been taken away from the valve chambers, what advantages does this have.

Logic on my behalf says it makes each cylinder slightly larger, ie 73.5mm=74mm, if you get my drift or am I waffling.

What is 'swept volume'?

What do you measure to get block height?

Cheers