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1592 for Racing

jdoclogan said:
The 1592 engine in stock form (dished pistons) has a compression of 9.1:1. If you install a flat top piston you will increase that ratio because you have eliminated the volume created by the dish in the stock piston. The increased ratio, say 10:1, will mean the mixture of molecules are under greater pressure increasing the heat (molecules banging into each other more rapidly because they are closer together [less volume]) generated prior to spark ignition of the mixture. Think of the 10:1 like there are 10 molecules per unit of volume measurement instead of only 9.1 molecules per unit of volume measurement for the 9.1:1 compression. The increase will allow for a more explosive combustion creating greater downward force of the piston. Thus, some increase in horse power. There is a practical caution to increasing the compression to say 12:1 or 13:1 or 14:1 etc. The force created puts greater stress on the molecular make up of the engine components. That can be the cause of some of the spectacular and flaming engine blowups during drag racing events. Too much compression can be thrilling and very expensive.
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Thank you. I did not know the earlier engines ran dished pistons. I have an SV with flat. Interesting thread, BTW
 
Eleven said:
Thank you. I did not know the earlier engines ran dished pistons. I have an SV with flat. Interesting thread, BTW
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The SV all had dished pistons as well in stock form. The 1725 piston while hsving the same bore as a 1592 has a larger dish to control rhe compression. It was a 7.5cc dish iirc
 
alpine_64 said:
The SV all had dished pistons as well in stock form. The 1725 piston while hsving the same bore as a 1592 has a larger dish to control rhe compression. It was a 7.5cc dish iirc
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So mine was rebuilt at some point?
I am starting a new thread on gasoline in Stock Alpine, I hope you can answer some questions for me. This is more interesting now!
 
I have been casually looking through my STUFF, for a piston that came out of an Alpine engine from England.

This piston fits the the "New school" concept of having a smaller pin.

The smaller pin lets you have a longer rod, a shorter piston and less reciprocating weight.

I'll find that piston eventually, in the mean time just use your imagination of a piston with a WAY smaller pin.

...even though it doesn't take full advantage of a longer rod...

DW
 
I found the piston.

The picture has a stock Alpine piston on the left.

The center piston is forged, for use with a Chevy rod/pin.

The right piston is used with a custom/GT6 rod with a .866 pin.

You can see there is Real Estate above the pin hole to move the pin up,

with a longer rod.

And/or a yet smaller pin.

IMG_20200723_083606794.jpg
 
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Eleven said:
So mine was rebuilt at some point?
I am starting a new thread on gasoline in Stock Alpine, I hope you can answer some questions for me. This is more interesting now!
Click to expand...

So you have flattops in your Series V? I don't remember your head having been shaved much, if any. If there's any hint of pinging, better back the timing off and/or start running supreme in it.
 
Dick, it does knock. I filled it with Supreme a bit ago but am concerned about the alcohol. I have a source of non alc gas but the octane is in the low '80's. I bought some octane booster but the instructions are not helpful: "Treats 24 gallons of gas. Pour the entire bottle into the tank before refill". Who has a 24 gallon tank? I have 6 gallons of room plus the 2ish that is in there. I guess I will have to try and scope out what 1/3rd of a bottle looks like. Helpfully, it has a very attractive multi-curve shape... I also got some alcohol treatment that is supposed to help protect against the bad stuff alc does.
I have the timing backed off a bit but don't want to go any more. Car is running great for the first time. We should take this off line, a little off topic.
 
spmdr said:
I found the piston.

The picture has a stock Alpine piston on the left.

The center piston is forged, for use with a Chevy rod/pin.

The right piston is used with a custom/GT6 rod with a .866 pin.

You can see there is Real Estate above the pin hole to move the pin up,

with a longer rod.

And/or a yet smaller pin.

View attachment 21715
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Dan, where did the "center piston is forged" come from?
 
A bit off topic, but does anyone have a source for flat top pistons? I did the Vizard on my series V head and want to get some of the compression back.
 
Thor, maybe because you are talking a STREET engine? But, YES, getting a flat top piston for an Alpine is a challenge!

I just ordered a set of flat top pistons, to go with the extra Long rods, from Racetec.

I have not decided what engine to build, 1592 or 1725. One factor I just added is the fact that I currently DON'T have 1592 in service..

DW
 
The center forged piston came used off ebay, but at this point, I'm not likely to put it back into service.

I just put it in the mix to show all the extra Real Estate above the pin location.
 
spmdr said:
Thor, maybe because you are talking a STREET engine? But, YES, getting a flat top piston for an Alpine is a challenge!

I just ordered a set of flat top pistons, to go with the extra Long rods, from Racetec.

I have not decided what engine to build, 1592 or 1725. One factor I just added is the fact that I currently DON'T have 1592 in service..

DW
Click to expand...

Was Racetec better to work with over Ross racing?
 
Well, Time will tell about Piston sources. Racetec is markedly less expensive than Ross.

However, Racetec is doing a Land office sales business, most likely because of price.

The good news is, at least in the past, Piston quality has been excellent from ALL sources.

...knock on wood...

DW
 
JP provides flat top pistons in various oversizes. Their skirt is a bit shorter that's why their weight is less than comparables. However they do come with crap 4 pc oil scraper rings. Don't waste any thought about them and replace with a modern 2 pc design:

Out of the box:
IMG_20211220_153940.jpg

Weight:
IMG_20190624_203843.jpg
 
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I would remind that this thread is in the Racing section...

So in that light, here are reasons NOT to use OEM spec pistons:

1) Piston is Too heavy.

2) Rings too big, heavy and inefficient.

3) piston pin Too big and heavy.

4) Pistons are cast.


For street use, the only thing of concern is #2, the rings.


For the record, the weights of the 3 pistons above are:


Stock type (+.040) 458g with 152g pin, 610g this also has the heaviest rings, not included here.

Chevy rod (+.060) 373g with 106g pin, 479g this would have med weight rings.

GT6 rod, (+.060) 380g unknown pin weight. this would have the lightest rings.


I expect the Racetec pistons to come in the range of 340-360 grams, with the potential of even lighter.

Hmmm, 2 pc oil rings are modern??
 
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