Input on power gains by swapping head.

[madkaw]

Is that also the small exhaust valve too- 33mm ?

Are you having any port work done?

[moelk]

35mm exhaust and 42mm intake.

It will be ported. 

[Diseazd]

On 8/14/2018 at 9:47 PM, 240260280 said:

Shave of 2mm off a P90 will put you ~9.9CR

 

 

Here is with E88 @44cc (~10.2CR):

You are showing the P90/P79 head cut 2mm with a 46cc chamber. Actually those combustion chambers are 44cc on those two heads after the cut. We (Eiji and me) cc’d The Head......they were 44cc’s. The head in the picture was cut again to give us a chamber cc of 44cc’s.

 

[240260280]

15 hours ago, Diseazd said:

You are showing the P90/P79 head cut 2mm with a 46cc chamber. Actually those combustion chambers are 44cc on those two heads after the cut. We (Eiji and me) cc’d The Head......they were 44cc’s. The head in the picture was cut again to give us a chamber cc of 44cc’s.

Thanks Guy!

Hmmm I trust both you and Brian Little but he gives 46cc here: http://datsunzgarage.us/p79/   and you have verified with two heads so I will default to you and update the tool... however can you please confirm both of your heads were not shaved before you received them?

 

Here is the revised tool: Z Engine Planner

 

 

 

 

S30 Engine Modeller V4.zip

Edited November 25, 2018 by 240260280

[Diseazd]

Blue....I’m not an expert, but the Datsun heads are 108mm from upper to lower surfaces. The measurement that are taken are from the top to give you 106mm result (2mm or .080 inches removed). If the head was previously cut .015 inches, the machinist would only cut the head .065 inches. I went back and checked the stats on Eiji’s Stroker that he built for me. The chambers were 44.5 cc’s not 44. I was there when he cc’d the engine, so I watched him cc the number one, number six and the number three chambers. All cc’d at 44.5 cc. Anyone else want to chime in?

Guy

[moelk]

107.9 mm i think is the messurment to be exact.

[240260280]

OK 44.5cc Thanks!

[rcb280z]

On 11/24/2018 at 3:50 AM, moelk said:

Will be running pump fuel 95 or 98.

Must be nice. The highest here is 91! And it cost WAY too much!

On top of that its oxygenated 6 months out of the year.

[moelk]

49 minutes ago, rcb280z said:

Must be nice. The highest here is 91! And it cost WAY too much!

On top of that its oxygenated 6 months out of the year.

The price on fuel is outrageous here to ; (

[rcb280z]

5 hours ago, moelk said:

The price on fuel is outrageous here to ; (

I forgot where you are. Yes its high there as well, $6.00 a gal? Its $4 plus per gal for the 91 here.

[moelk]

16 minutes ago, rcb280z said:

I forgot where you are. Yes its high there as well, $6.00 a gal? Its $4 plus per gal for the 91 here.

If i got the numbers right (gal-liter, dollar-sek) we are at $6.30 a gal 98 and $5.80 for 95.

[rcb280z]

Well at least we don't live in Switzerland. Over $11.00 a gallon.

Correction; I mean Iceland, not Switzerland. Have some friends that went to Iceland recently 

Edited November 25, 2018 by rcb280z