Beefing up a 1600

[Jack Cedarholm]

I have a 1600 '61 356 B I would like to beef it up to a 90 hp. I notice in the technicals everything is the same except the carburator. Bore, stroke, displacement all the same. I notice the compression goes up from 7.5 to 9.1 and the bearings go from 50 to 55. So is the crank bigger and that is the way I get more compression? Does putting on a 40PII-4 make the difference? How would you beef it up if you were me?

By the way there is a Porsche get together I was told about from a friend of mine who belongs to the PCA club. It is in Huntington Beach on May 30, 31 and June 1. All porsches rare welcome, for those who are in southern California.

Jack

[Cliff Murray]

Do you have a Normal or a Super? If you have a Normal, you have to change the cam to get 90hp. If you have a Super, the cam is ok. You will need a 1720cc kit and set it up to near 9.5:1 with matched squish angles. The carbs will need to be modified or replaced with bigger ones. The intake ports will need some attention. Talk to your local 356 engine builder to establish a plan before you start.

[charles kourmpates]

I have a 1600 '61 356 B I would like to beef it up to a 90 hp.

Jack,

It's your engine so you can do whatever you please to it to "beef it up."

But, I personally, would put my resources and efforts into a 912 engine. :mrgreen:

You'll have a lot more to show for it when your done, plus you'll also have the "original" engine.

With all the "gadgets" now available, the change to 12V can be accomplished a bit easier.

I have no regrets for my Spencer built 912 or my efforts to change to 12V.

Works for others! Works for me!

[Norm Miller]

Jack,

First get a copy of Spencers book on engine mods.
Study it for a while and sort out some options.

Remember; the only way to beat cubic inches is with cubic dollars.

norm

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[Jack Cedarholm]

Thank you all for your input. What puzzles me is that I went to Pelican Parts Technical information. I found the following: Stroke for both is 74, Bore for both is 82.5mm, True displacement for both is 1582, Bearings 1,2,3 change from 50 to 55, Intake opens from 7 to 53 degrees and exhaust closes from 44 to 50. that is all mechanical oh and the carbs change from 32NDIX to 40PII-4. So if the bore and stroke are all the same, are the heads different that the degrees change? What causes the compression increase? Is it a larger crank indicated by the change of bearings? or is it a larger cam that changes the opening and closing of the valves?



By the way any recommendations on where to get Spencers book?



Thank you for your information. That is why I like the blog

[Ron LaDow]

Jack,

"What causes the compression increase?
Jack Cedarholm"

Compression ratio is a measure of the volume in the combustion chamber with the piston at top dead center compared to the volume in the cylinder and chamber with the piston at bottom dead center. If you're not familiar with interncal combustion engines, it will take a bit of study to understand.
Here's a couple of links:
http://www.356registry.org/Articles/LaDow/
http://www.precisionmatters.biz/pdf/com ... -ratio.pdf
Thanks,
Ron LaDow

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[Richard Towle]

Thank you all for your input. What puzzles me is that I went to Pelican Parts Technical information. I found the following: Stroke for both is 74, Bore for both is 82.5mm, True displacement for both is 1582, Bearings 1,2,3 change from 50 to 55, Intake opens from 7 to 53 degrees and exhaust closes from 44 to 50. that is all mechanical oh and the carbs change from 32NDIX to 40PII-4. So if the bore and stroke are all the same, are the heads different that the degrees change? What causes the compression increase? Is it a larger crank indicated by the change of bearings? or is it a larger cam that changes the opening and closing of the valves?



By the way any recommendations on where to get Spencers book?



Thank you for your information. That is why I like the blog

The power in these motors is made in the heads, valves, CR, and exhaust/intake.
Saying that is simple.
The motor you have is a balanced system. If you change one thing you need to change all of them to really get a newly designed well balanced motor.

Look at the torque curves for your motor, the super 90 motor, and the SC/912 motor.
You will see that the power is made at a different rpm range, not the same place.

Increasing the CR (compression ratio) creates more power, but it also creates more heat.
So, you need bigger valves, and better exhaust to get rid of the heat.
You will need more fuel (larger carbs) to get the power.
You will need a more aggresive camshaft with more overlap to get more power.

If 90 hp is your goal, copy the super 90 parts and build it.
If you want more, start with an sc/912 motor, the heads are better.
Rich

[Martin Hirst]

The power in these motors is made in the heads, valves, CR, and exhaust/intake.

Is the bottom end of a standard 61 Super or Normal strong enough without modifications to reliably take an increase in power to S90/SC levels?

[Ron LaDow]

Martin,

"Is the bottom end of a standard 61 Super or Normal strong enough
without modifications to reliably take an increase in power to
S90/SC levels?
Martin Hirst"

Yes, but S90/SC HP numbers are found at relatively high RPMs. High crank speeds means shorter life, all else being equal.
Thanks,
Ron LaDow

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[Jon E. Askins]

I have a S90 and was thinking about selling it to replace it with more period engine for my 57 Coupe(1600cc was factory). Anyone know a good price for complete with all carbs and everything on it, less the surround metal for the dessing off of the enclosure?