Five Reviver
Silver Level Sponsor
And yes, 1725, stock stroke
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Enjoy.
New School Custom Pistons
- Thread starter spmdr
- Start date
alpine_64
Donation Time
What exchange rate did you get? Aue has been hammered lately
Five Reviver
Silver Level Sponsor
It was not so good, about .64. This brought the price to about the same as estimated by SPS in Melbourne, who I would have got to do it but for a 15 week turnaround.
spmdr
Diamond Level Sponsor
Sounds good!
I wonder how much delay you would get with a different Bore size.
And the next time I order, I'll talk to them about the limits of putting the piston on a diet.
The Forging is designed for a dome and could be thinned quite a bit.
Seeing I have 2 sets of pistons, I'm thinking I should do a stock stroke 1725,
And a stroked 1592.
...save on the cost of gas for the machining, if I divide the cost by 2...
DW
I wonder how much delay you would get with a different Bore size.
And the next time I order, I'll talk to them about the limits of putting the piston on a diet.
The Forging is designed for a dome and could be thinned quite a bit.
Seeing I have 2 sets of pistons, I'm thinking I should do a stock stroke 1725,
And a stroked 1592.
...save on the cost of gas for the machining, if I divide the cost by 2...
DW
alpine_64
Donation Time
Justified economically like a true car enthusiast
Five Reviver
Silver Level Sponsor
The VW/Audi rods look more than plenty strong too. I’m guessing if money was no object you could have them made a bit lighter or, if you’re brave, a little surgery perhaps…
Always interesting what I get to read here. But today I would like to contribute something on
the subject of New School Piston. Since 2014 move in my Alpine also New School pistons.
After a long search, I found BMW E46 , 318i, pistons with 84 mm diameter that I have installed with matching
Conrods in my Alpine.
So far - after almost 20000 km - without problems. Not a race car but certainly not driven by a girl
.
I'll try to post a picture. That says more than a few words.
regards
Thomas
the subject of New School Piston. Since 2014 move in my Alpine also New School pistons.
After a long search, I found BMW E46 , 318i, pistons with 84 mm diameter that I have installed with matching
Conrods in my Alpine.
So far - after almost 20000 km - without problems. Not a race car but certainly not driven by a girl
.I'll try to post a picture. That says more than a few words.
regards
Thomas
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Hi Dan, my head gasket is the original head gasket. So far without complications. Better would be
a matched gasket to the larger bore. But works fine with the many other modifications that have
been made.
I had the conrods made by Andy ( WMS ) in 2013 to my own drawing. The data should still be with him
if anyone is interested.
For information: the pistons weigh 389 g, compression height 27.5 mm. The Conrods are unfortunately
only 30 g lighter than the stock conrods. Potential for reduction is available, however.
I had to approach the dimensions and try what is possible.
My next step was CNC machining the cylinder head and fabricating 39,8/32/7 mm valves to increase performance.
a matched gasket to the larger bore. But works fine with the many other modifications that have
been made.
I had the conrods made by Andy ( WMS ) in 2013 to my own drawing. The data should still be with him
if anyone is interested.
For information: the pistons weigh 389 g, compression height 27.5 mm. The Conrods are unfortunately
only 30 g lighter than the stock conrods. Potential for reduction is available, however.
I had to approach the dimensions and try what is possible.
My next step was CNC machining the cylinder head and fabricating 39,8/32/7 mm valves to increase performance.
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jdoclogan
Platinum Level Sponsor
Nice work Tom. My head flow test (https://forum.sunbeamalpine.org/index.php?threads/head-flow-test-results.31401/) found the 39.14mm intake and 35mm exhaust provided the optimum flow.
I would never have guessed that the ratio of the inlet valve to the exhaust
valve is so low? My engine guy gives 33 mm exhaust valve as max. size.
But here I have to make a small correction to my specifications. I looked in my files
and noticed that my valves are 39.8 mm / 32 mm / 7 mm. The valves were bought as
blanks and then machined .
valve is so low? My engine guy gives 33 mm exhaust valve as max. size.
But here I have to make a small correction to my specifications. I looked in my files
and noticed that my valves are 39.8 mm / 32 mm / 7 mm. The valves were bought as
blanks and then machined .
Hi Dan, the rods are a little longer. From the middle of the big end to the middle of the small end
the dimension is 162.3 mm. Compression height of the piston 27,5 mm !
My first cylinder heads I have still in manual work on the Vizzard Modefikationen. But then it
was too much work for me.
I like to be a lazy guy .
I then measured the heads exactly, created a DXF file and had the combustion chambers CNC machined
by friends. All combustion chambers now have absolutely the same volume.
The channels were also CNC machined the first 10mm. The fine work was done by hand.
What would interest me is the power your raca cars on the Dyno. I have already
read 170HP which seems to me but very high ?
Regards
T
the dimension is 162.3 mm. Compression height of the piston 27,5 mm !
My first cylinder heads I have still in manual work on the Vizzard Modefikationen. But then it
was too much work for me.
I like to be a lazy guy
.I then measured the heads exactly, created a DXF file and had the combustion chambers CNC machined
by friends. All combustion chambers now have absolutely the same volume.
The channels were also CNC machined the first 10mm. The fine work was done by hand.
What would interest me is the power your raca cars on the Dyno. I have already
read 170HP which seems to me but very high ?
Regards
T
alpine_64
Donation Time
@Tom13
Are the walls of your chambers straight or do they taper down towards the valves?
The shape seems similar to what Jarrid did years ago .. Not a full vizard .. But increase flow and flame front but not take put to much compression.
@RootesRacer ... You should really be in on these threads.
Are the walls of your chambers straight or do they taper down towards the valves?
The shape seems similar to what Jarrid did years ago .. Not a full vizard .. But increase flow and flame front but not take put to much compression.
@RootesRacer ... You should really be in on these threads.
@alpine_64
The combustion chamber is tapered by 4° towards the valves. Of course, it is not machined
exactly according to Vizard, but it roughly takes the shape.
However, it seems to work ? The engine runs really well in conjunction with all the
other modifications.
Dan,
I will check if I can still find the file. What I have in any case is a drawing in PDF and in paper.
Tom
The combustion chamber is tapered by 4° towards the valves. Of course, it is not machined
exactly according to Vizard, but it roughly takes the shape.
However, it seems to work ? The engine runs really well in conjunction with all the
other modifications.
Dan,
I will check if I can still find the file. What I have in any case is a drawing in PDF and in paper.
Tom
alpine_64
Donation Time
Tom. If you have the pdf i can turn that into a CAD file
I found the drawing on paper immediately. The PDF file should be on my other PC. I will look t
here tomorrow.
But back to my question.
What do you do in the States to tune the engines ? Is 160 - 170 HP really possible ?
Even with big valves, CNC machined Cc , Race Cam , machined ports, lightened flywheel,
adjustable camshaft sprocket and Weber carburetors I can't get close.
here tomorrow.
But back to my question.
What do you do in the States to tune the engines ? Is 160 - 170 HP really possible ?
Even with big valves, CNC machined Cc , Race Cam , machined ports, lightened flywheel,
adjustable camshaft sprocket and Weber carburetors I can't get close.
Attachments
spmdr
Diamond Level Sponsor
Tom, I FEEL your PAIN!! Check out this:
https://forum.sunbeamalpine.org/index.php?threads/alpine-engine-power-limitations.30152/
I don't know about 160HP or more, but I'm working on/Hoping for 150 ish to the crank of a 1750cc ish Alpine engine.
Others have gotten more than 150 HP out of an Alpine engine, BUT with the Path of MORE ccs.....
DW
https://forum.sunbeamalpine.org/index.php?threads/alpine-engine-power-limitations.30152/
I don't know about 160HP or more, but I'm working on/Hoping for 150 ish to the crank of a 1750cc ish Alpine engine.
Others have gotten more than 150 HP out of an Alpine engine, BUT with the Path of MORE ccs.....
DW
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Five Reviver
Silver Level Sponsor
Dan,
I have a couple of questions for you regarding the new school RaceTec pistons. Mine are the same spec as yours.
I have put these questions to RaceTec as well but thought that if you happen to know the answers already, they may be of interest to the forum. Or you might prefer to wait until I post the answer from RaceTec!
(All numbers below e&oe!)
By my calculation there is scope to offset my big end journals by up to 2.9 mm leading to a 5.8 mm increase in stroke, which would lead to a displacement of 1872 cc.
This would require milling of up to 2.9 mm from the piston crown. Have you been told by Racetec how much removal of material the design will accommodate?
Even if the piston itself would accommodate removal of 2.9 mm, there is then the question whether the distance from top of piston to the top ring would then be sufficient? It would be reduced from .30 inches or 7.62 mm to .1858268” (not to put too fine a point on it!) or 4.72mm.
David
I have a couple of questions for you regarding the new school RaceTec pistons. Mine are the same spec as yours.
I have put these questions to RaceTec as well but thought that if you happen to know the answers already, they may be of interest to the forum. Or you might prefer to wait until I post the answer from RaceTec!
(All numbers below e&oe!)
By my calculation there is scope to offset my big end journals by up to 2.9 mm leading to a 5.8 mm increase in stroke, which would lead to a displacement of 1872 cc.
This would require milling of up to 2.9 mm from the piston crown. Have you been told by Racetec how much removal of material the design will accommodate?
Even if the piston itself would accommodate removal of 2.9 mm, there is then the question whether the distance from top of piston to the top ring would then be sufficient? It would be reduced from .30 inches or 7.62 mm to .1858268” (not to put too fine a point on it!) or 4.72mm.
David
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