Stroker Possibilities.....

Tech tips and how to's

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Daryl Smith
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Stroker Possibilities.....

Post by Daryl Smith »

I came up with this stuff while in the process of building my motor, and reading on this list and the email list. I have only built the 1800cc R/G engine myself. No experience building the other engines mentioned, but it only makes sense that if one crank will fit in one engine then it should also fit in the other....

IF any of this information is incorrect, or you think something should be added please let me know so I can correct my mistakes.
Thanks
Daryl Smith

This is for information purposes only. Please do some research on your own before you get a bunch of parts together that may not work!

Building an R, G, (H?) Series Stroker Engine? (Possible Combinations)

The stock pushrod engines in the roadsters came in 1500cc (G) and 1600cc (R) displacement. It is possible, if you want to keep your car looking stock, to significantly increase the performance of these engines by "stroking" them. That is rebuilding them with a crankshaft with a longer stroke.

1. The 1500 ‘G’ engine can be stroked to around 1700cc using the 3 main H 19 crankshaft with an 83mm stroke. This crank is probably rarer than the 1500 crank tho….Also, you have to find a rod/piston combo to fit. The 1500 engine has an 80 mm bore and, it seems, a 2 mm shorter deck height than the R/H/U engines, so pistons from those engines will not work.

Suggestion: R 16 rods and custom pistons.

2. The 1600 ‘R’ 3 main engine can be stroked to around 1800cc using the ‘G’ crankshaft (74 mm). Unfortunately, you end up in the same situation as above, where the parts are not available off the shelf to bolt in.

Suggestion: R 16 rods and custom pistons. (This is the engine that I built.)

3. The 1600 ‘R’ 3 main engine can also be stroked to around 2000 cc using the above mentioned H 19 crank (83 mm). If you use the 83 mm crank you can use the stock H 20/U 20 rods and pistons. (There may be a 3 main H 20 crank out there as well….)

4.The 1600 ‘R’ 5 main engine can be stroked to about 2000 cc using either the H 20 or U 20 crankshafts (both @ 83mm stroke) This is the most popular, easiest and cheapest engine to stroke. The parts are all off the shelf and bolt in for the most part, using H 20 or U 20 rods and pistons. You can also just use an H 20 forklift shortblock and bolt on your R series head. A couple of these engines are outlined on the 311s.org site.

5. While technically not a ‘stroker’ engine, IF you were to find an H 19 (1883 cc) engine, it is quite ‘probable’ that it will also bolt in whole to the roadster. (**Disclaimer – This is pure speculation, considering the H 20 will bolt up!**) Although I don’t know what the head is like. It may benefit from an R 16 head transplant. Also assuming the R head will bolt on.

So. There you have it. IF you like (and can find the parts) you have a choice of pushrod engines in 1500, 1600, 1700, 1800, 1900, or 2000cc variants.

Other Notes

Rod Length and Rod Ratio: Much has been written about rod length and rod ratios and the benefits of longer or shorter rods. Rod ratio is the length of the connecting rod divided by the stroke of the crankshaft. The ONLY piece of information that I have found consistent is that a longer rod provides less "side loading" (pushing the piston into the wall of the cylinder) and therefore more force (?) to the crank. Smokey Yunick suggested in his book that ratios as high as 3:1 might be beneficial. (The R 16’s rod ratio is 2.3:1). Some prefer a shorter rod with ratios around 1.5 to 1.6:1. There seems to be a growing consensus that a ratio around or just over 1.7:1 may be the magic ratio….

I lean to the long rod side of things. That’s why I suggest using the R 16 rod. This should give you a shorter, lighter piston. I don’t know if that is offset by the extra weight on the longer rod tho…..??

Parts Swapping

An option to the custom parts is to find parts from other engines that can fit with a little work. IE: Sometimes a piston can be found with the correct pin diameter, workable but non-standard bore, and a pin height that is close. There have been rumors that a version of Nissan VG 30 pistons will work with the R 16 rods with the 83 mm stroke (H 20/U 20) for a 2L. I was looking at some Chevy Luv pistons for my 1800, which would have required me to mill about 1-2 mm from the block. If you’ve got the time, and access to the books, I’m sure there are some ‘off the shelf’ parts from something that can be made to work with your combination of parts.

With the above in mind, the following information should help you find the right combination of parts or the dimensions for your custom pieces:<table><td></td><td>G15</td><td>R16</td><td>H19</td><td>H20/U20</td></tr>
<td>Displacement</td><td>1488 cc</td><td>1595 cc</td><td>1883 cc</td><td>1982 cc</td></tr>
<td>Bore(mm)</td><td>80</td><td>87.2</td><td>85</td><td>87.2</td></tr>
<td>Stroke(mm)</td><td>74</td><td>66.8</td><td>83</td><td>83</td></tr>
<td>Rod Lenght(mm)t</td><td>144</td><td>152.45</td><td>?</td><td>144</td></tr>
<td>Piston Height(mm)</td><td>44</td><td>41</td><td>?</td><td>41</td></tr>
<td>Deck Height(mm)</td><td>~225</td><td>~227</td><td>?</td><td>~227</td></tr>
<td>Rod Ratio(mm)</td><td>1.95:1</td><td>2.28:1</td><td>?</td><td>1.73:1</td></tr>
<td></table>

*You must measure your block to get the proper 'deck height' to calculate your 'piston pin height' for custom/other pistons. Or custom rods for some other piston….. These figures are close ONLY if the R 16 rod is used. It is not recommended to go more than 0.5 mm above the block deck.

** Again with the R 16 rod. If you use H 20/U 20 rods see that column…….

Deck height, or block deck height is the distance from the center of the crankshaft to the top of the block. Given a certain "block deck height" you need a combination of parts, which will be close to that height. Very close.


The formula is "1/2 stroke + rod center to center length + piston pin height = ~block deck height"


For a stock 1500, 1/2 stroke = 37mm
rod c to c = 144mm
pin height = ~44mm
total = ~225mm
(I say ABOUT 225mm because the factory should make it close to the top of, but generally not even or over the top of, the block. Also these engines are OLD and have likely been rebuilt and the block "decked" to make it flat again, taking ~0.010"+ off. You MUST measure YOUR block to get it right.)

So, any combination of parts you swap in should be close to 225 mm for the 1500 block (or 227 mm for the 1600 block). It is not recommended to go more than 0.5 mm above the block deck.


With the 83mm crank stroke you have a choice of custom rods or custom pistons. 1/2 stroke = 41.5mm
225mm minus 41.5mm = 183.5mm to share between rod & piston.

If you use the H 20 or G 15 rod (both are 144mm), 183.5 minus 144mm leaves 39.5mm for pin height for a custom piston.

If you use an R 16 rod (152.45mm), 183.5 minus 152.45 leaves 31.05mm for pin height for a custom piston.

If you were to use the stock piston @ ~44mm, then, 183.5 minus 44mm leaves 139.5mm for your rod. That is 4.5mm shorter than the stock rod and the same as 1/2 of the stroke INCREASE.

Generally I believe it is cheaper to get custom pistons than custom rods, but you can check that for yourself.

Above ALL check with your Machinist BEFORE you embark on a project like this to discuss your options. AND make sure you get ACCURATE measurements - measure TWICE (three times?) and order once!! A custom part that doesn't fit is frustrating and expensive!!

Calculating Displacement
Displacement = Bore x Bore x .7854 x Stroke x Number of Cylinders

(Use Centimeters since we want Cubic Centimeters Displacement)

Example: G 15
8.0 x 8.0 x .7854 x 7.4 x 4 = 1488 cc

G 15 with H 19 crankshaft:

8.0 x 8.0 x .7854 x 8.3 x 4 = 1669 cc

(a 1.0 mm overbore takes it to 1710 cc)

R 16 with G 15 crankshaft:
8.72 x 8.72 x .7854 x 7.4 x 4 = 1768 cc

(an 88mm bore takes to 1800 cc)

R16 with H 19/H 20/U 20 crankshaft:

8.72 x 8.72 x .7854 x 8.3 x 4 = 1982 cc

(a 1.5 mm overbore takes it to 2052 cc)
Daryl
'66 2065cc Stroker "Frankie", Megasquirt EFI and Ignition
she aint pretty, she just looks that way...
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shifty
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Post by shifty »

Good info!

Tell us more about your stroker.
Leigh Brooks

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ppeters914
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Post by ppeters914 »

Another option recently mentioned on the Bluebirds list:
try http://zhome.com/rnt/3.1HanveyProject.htm

>From: Victor Laury <vlaury>
>Date: 2006/11/29 Wed PM 07:29:42 CST
>To: Andy Cost <andycost>, datsun-roadsters@autox.team.net
>Subject: Re: Stroker Z from L24?

>As Andy said, The quickest fastest way is get an L28. I have one Free,
>If you can get from down stairs to your truck. Took me most of one
>whole day just to get an L16 up from there!
>
>The 3.1 stroker starts with an L28 block, the LD24 crank, KA rods and I
>can't remember which pistons. But if you Google L28, F54, LD24, you'll
>most likely find the web page that descibes the 3.1 recipe.
>
>
>
>Victor
>Downtown Los Angeles
>70 SRL
>70 521
>71 521
>72 240Z
>http://www.fotki.com/datsunvic/
Pete
-------------------------------------
'67 1600 - frame off started in 2014. Now I know why roadster projects take so long. What a stupid idea. :smt021
'66 1600 - parts car
'66 WPL411 ***SOLD***
A couple of Porsches, a RAV4 Hybrid, and a motorcycle
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Daryl Smith
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Post by Daryl Smith »

Pete,
I just realized I have NEVER seen an inline 6 in the roadster! V6, V8's and a load of different 4 bangers, but never an inline 6. You gonna try it? :lol:

Leigh,
Motor specs are at the bottom of this post:
http://www.311s.org/phpBB2/viewtopic.php?t=5340

Cheers
Daryl
'66 2065cc Stroker "Frankie", Megasquirt EFI and Ignition
she aint pretty, she just looks that way...
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ppeters914
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Post by ppeters914 »

DOH! Never mind....I'm a moron. :oops:
Pete
-------------------------------------
'67 1600 - frame off started in 2014. Now I know why roadster projects take so long. What a stupid idea. :smt021
'66 1600 - parts car
'66 WPL411 ***SOLD***
A couple of Porsches, a RAV4 Hybrid, and a motorcycle
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spl310
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Post by spl310 »

I have seen photos of not just one, but TWO L28 powered Roadsters. One was a nicely done red one while the other was a rat. It can be done...
"Wow, a Roadster!" Stuart Little

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