2.5 Monster Motor

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nkro
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Re: 2.5 Monster Motor

Postby nkro » Mon Jul 23, 2012 1:29 pm


Darth Blomqvist
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Joined: Mon Aug 08, 2011 10:52 pm
Nickname: kip
Number of Saabs currently owned: 4

Re: 2.5 Monster Motor

Postby Darth Blomqvist » Mon May 04, 2015 11:23 am

Apparently when I said that I was going to be, ‘getting some of this R&D together by the end of the summer’, I forgot to say end of the summer -2015…

I’m nearing the end of my rotations for work and will finally be back in CT after two years this July. It will be really nice to be back home and close to my family, friends, tools, and Saab stuffs!

I need a little help from the community though to verify some dimensions. I have most of the measurements for this motor mapped out from Saab shop manuals and physically measuring parts to verify. I have confirmed most of them but I’m a little suspect of the 2.1 block measurement I have.

Does anyone have a 2.1 block out and handy to measure? I need to verify the center of the crank to the top of the deck (Before finalizing measurements and ordering pistons).

I currently have the block height minus ½ crank/main bearing at: 7.160” or 181.864 mm, with the total block height at 8.381” or 212.8774 mm. Can anyone verify this?
Any verification on the 2.1 block measurements would be a great help.

I’m getting a lot closer to actually moving this forward and will post more in the coming weeks after I have finished the rag tag blue prints and ordered pistons.

On a side note, some of you may know that the Chevy rods are quite narrow at .9472” or 24.0588mm compared to the stock Saab width of 1.038 or 26.3652mm. That means there is close to .0020” or .052mm slop on each side of the rod main. The stock Saab Rod journal for the early 2.3 crank is 2.0465” or 52.451mm.

Does anyone know if the Swedish folks just ran the stock width chevy rods, and didn’t worry about the couple of thousands ‘extra’ clearance on each side? I have been told this will affect oiling and bearing wear… But I would be curious to know if any of the Swedes had custom rods made? I’m guessing if your building a folk racer and keeping cost down you would just run the chevy rods you can buy off the shelf and not worry that much about longevity?

More to come.

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Geoff
Team Turbo Troll Crew
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Re: 2.5 Monster Motor

Postby Geoff » Mon May 04, 2015 12:02 pm

Sounds like your slop calculations are off. I come up with 0.045" slop per side.

Would those Toyota rods that Luke is using work instead?

I have a 2.1 block handy I could measure. I won't get a chance to do it until a week and a half or so from now though.
Did you measure this before? If so, what method did you use to measure?
The kind of dirty that doesn't wash off :eyebrows:

Darth Blomqvist
Posts: 40
Joined: Mon Aug 08, 2011 10:52 pm
Nickname: kip
Number of Saabs currently owned: 4

Re: 2.5 Monster Motor

Postby Darth Blomqvist » Mon May 04, 2015 4:25 pm

Sorry,

The stock Saab rod journal width is 1.050’’ or 26.67mm and the stock journal itself if 2.0463" or 52.451mm, I didn't read my drawing correctly.

So the stock Saab rod at a 1.038’’ width would have 0.012” spacing/’slop’ or .006”on each side of the rod from the factory. And the stock Chevy rods with a .9420’’ width would have 0.0108’’ spacing/’slop’ or .054’’ on reach side.

Either way you are right my math was wrong. That being said that is a lot of space.

Has anyone had any experience running something like that? I thought it could be ‘made up’ or captured on the piston side, but I have not had that confirmed yet.

The Toyota rods are 5.276’’ center to center where the Chevy rods are 5.7” center to center. I could definitely go that route, but I believe the Toyota rod length is not that much more than stock I think Luke stated .5mm center to center longer? Right now with 94mm bore, and a 89.992mm stroke this gets to a 2.49L motor. These pistons will be quite short… But the rod ratio is 1.63 rod length/stroke with the Chevy rod. I think that is good/safe from what I've read as far as side loads..

As far as the measurement of the block height it was done with a long set of calipers from the top of the main journal to top of the block. I then measured the crank main thickness. I know there is a more accurate way of doing this; I just wanted to get into a ballpark that if someone had a detailed Saab shop manual they could verify that I am close or what Saab has as documented? I am not going to order pistons if I don’t have it very accurately measured, I was just hoping someone had a spec sheet or bare stock block handy.

I’ll post what I have drawn up in the next couple of days.

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Luke
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Re: 2.5 Monster Motor

Postby Luke » Wed May 06, 2015 8:27 am

Darth Blomqvist wrote:Does anyone have a 2.1 block out and handy to measure? I need to verify the center of the crank to the top of the deck (Before finalizing measurements and ordering pistons).

I currently have the block height minus ½ crank/main bearing at: 7.160” or 181.864 mm, with the total block height at 8.381” or 212.8774 mm. Can anyone verify this?


More to come.


Hey Kip, I can provide a sanity check to your measurements based on known dimensions of the stuff I'm putting together:

1/2 crank stroke: 1.535"
Rod Length: 5.315"
Piston CH: 1.535" (pretty interesting that's it's exactly half the stroke)

= 8.385"

All assembled it comes up about 1-2 thou below and uncut 2.1 deck.


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