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Engine Specific Info and Questions => IDI Engine => Topic started by: Gizmoman on November 17, 2012, 10:49:24 am
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What is the piston pin diameter supposed to be for an AAZ?
My pin diameters are 23.95 mm. I recently acquired a new set of Nural pistons (1st OS), pins and Gotze rings. I had already heard that the Nural pins were thinner than the stock pins and also were not as tight as they should be so I planned on using the stock ones.
The Bentley says that I should have to warm the piston a bit to remove the pin - these slide out if you tip the piston sideways and my stock pins are way too small. The pins in the Nural pistons are 25.95 mm and will not fit the stock rods! Am I supposed to ream the rod ends to make the pins fit (surely not).
I was hoping to get my block bored this week but I'm thinking these pistons are crap.
Please, any advice appreciated.
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Aaz have 26mm wrist pins, im guessing what you have is not really an aaz I believe some of the na and industrial 1.9 idi engines had the smaller wrist pins like a 1.6 and also longer rods, so the pistons are almost conpletely different too, its probably easier for you to find aaz rods, I believe tdi rods will work too
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TrevOrbr
Thanks for pointing this out. I really wish I knew the history of this motor. It's getting another step clearer now.
The pump and mount was a 1.6 but Giles has re-done it and say's it will work fine for me. The block is defiantly an AAZ cause it's cast into the block (edit) - 1.9 is cast into the block not AAZ) and the bore is 79.48 mm. I guess that means it was an industrial engine? Were any of these turbocharged? Mine has the oil squirters and a K14.
What would you think of bushing the new OS pistons to fit the smaller pin? That would take care of the pin being loose in the piston ;D
The Nural piston is 6.14 mm taller than my piston (bottom of skirt to face). I slid the pins in both and lined them up face to face on the pins with them sticking out a bit. It looks like the pins line up perfectly. That means the new pistons will stick out of the bores by a huge amount.
The rods are too long for sure - defiantly pointing to in industrial engine (and new rods required).
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Easiest and safest thing to do is probably just to get other rods, then you'll have all the more common parts in your engine too so that would make life easier in the future
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What engine code is it? 1y?
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Hmm, Don't know where to find that info.
There's an 80HBH on the right when facing the front of the block - right next to cylinder 1.
Near the #4 barrel on the right, there is 140 4
There's also a series of numbers stamped on a machined surface just below #3 - 370 015
The left side says 1.9 TD
That's about it.
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Measure the rods center-to-center and post back your readings. I'll take measurements on mine and we'll compare.
Sorry to hear the pistons I sold you won't work off the bat (P.S. they're ARCO not Nural, but I thought I told you that ???); do the rings measure good end gap?
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Yea - the pistons are ARCO's not Nural. Can't check the ring gap till it's bored and I won't get it bored till I get this sorted.
The rods are roughly 150 mm from crank center to pin center.
I'm not building a drag engine but all I can find are spendy rods http://www.partsplaceinc.com/products/product-detail.aspx?keyword=VW+TDI+Connecting+Rod+Set+28-198-401&s=91&&sku=18411 (http://www.partsplaceinc.com/products/product-detail.aspx?keyword=VW+TDI+Connecting+Rod+Set+28-198-401&s=91&&sku=18411)
If anyone knows a source for good stock rods for less than 500 bucks, let me know.
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What engine code is it? 1y?
My answer Hmm, Don't know where to find that info.
There's an 80 HBH on the right when facing the front of the block - right next to cylinder 1.
Near the #4 barrel on the right, there is 140 4
There's also a series of numbers stamped on a machined surface just below #3 - 370 015
The left side says 1.9 TD
There is another number cast along the right side about in the middle of the block - 028103021 AC (as far as I can make out).
Anyone know how I figure out my engine code?
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You have 1,9na rods, several different engine codes for that. It's probably easiest for you to find 144mm 1,9 turbo rods.
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Thanks MJF - I have a line on an ideal fix from a member.
From what I have found so far, if there are no numbers on the face of the engine - it probably is an industrial engine. But I really don't know if that's a sure thing or not.
Seems odd someone would put NA pistons and rods in a turbo diesel engine but who knows the circumstances at the time.
The block says 1.9 TD and it has oil squirters. Not sure if all the 1.9 had squirters but I've heard they were not used on NA engines.
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It sounds to me like someone has turbocharged a 1Y 1.9 N/A engine. The 150mm conrod lengths and gudgeon pin diameter is the give away for that.
Some 1.9 diesel engine conrod specs.
1Y IDI NA = 150mm long, gud pin 24mm
AAZ IDI TD = 144mm long, gud pin 26mm
1Z TDI = 144mm long, gud pin 26mm
Some 1.9 N/A engines did have piston coolers, at least the ones I have stripped.
(http://i1001.photobucket.com/albums/af136/original_danster/DSC00567.jpg)
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1Y IDI NA = 150mm long, gud pin 24mm
AAZ IDI TD = 144mm long, gud pin 26mm
1Z TDI = 144mm long, gud pin 26mm
It amazes me how many variations of these engines there are - and you are only listing 1.9's.
Thanks for the info - very helpful. I may have a line on a block, rods, and pistons so I may end up with a spare block, short pistons and 150 mm rods. . . just like the big boys now - I have a pile of VW diesel parts I'll never use ;D
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It seems my 1.9 is/was an industrial engine with 150 mm rods and 25 mm pins (with shorter than stock pistons).
The industrial rods were 150mm long and the ones I should have soon ;D will be 144 mm (including standard pistons).
An Engineer at work pointed out that this (shorter rod) will likely move the torque curve up higher on the RPM scale. Anyone here have numbers to verify that?
It makes sense, and would be great if it does change it. My vanagon cruises around 3850 at 70 and with the long rods (it had) was outside the "sweet spot" I believe. This is probably one of the reasons it worked so hard on slight grades on the freeway (besides having the profile of a barn door).
Would appreciate confirmation of this - torque curves of 1.9 with 150 mm rods VS 144mm would be sweet.
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It seems my 1.9 is/was an industrial engine with 150 mm rods and 25 mm pins (with shorter than stock pistons).
The industrial rods were 150mm long and the ones I should have soon ;D will be 144 mm (including standard pistons).
An Engineer at work pointed out that this (shorter rod) will likely move the torque curve up higher on the RPM scale. Anyone here have numbers to verify that?
It makes sense, and would be great if it does change it. My vanagon cruises around 3850 at 70 and with the long rods (it had) was outside the "sweet spot" I believe. This is probably one of the reasons it worked so hard on slight grades on the freeway (besides having the profile of a barn door).
Would appreciate confirmation of this - torque curves of 1.9 with 150 mm rods VS 144mm would be sweet.
It's more likely than anything that you will not notice a difference. But your engineer friend has 2 things confused, rod length and stroke length(get the giggles out before u continue reading). A shorter stroke is better for higher rpm power. The stroke length is determined by the crank shaft which you are not changing. A shorter rod actually is better for lower end power because the rod gets closer to a 90 degree angle which produces more torque. The down side is that the rod flops back and forth more so it is a bit weaker and not as safe at higher rpms, but I don't think u will notice much if any difference and I don't think these slightly shorter rods will at all effect the life of your engine
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It's more likely than anything that you will not notice a difference. But your engineer friend has 2 things confused, rod length and stroke length(get the giggles out before u continue reading). A shorter stroke is better for higher rpm power. The stroke length is determined by the crank shaft which you are not changing. A shorter rod actually is better for lower end power because the rod gets closer to a 90 degree angle which produces more torque. The down side is that the rod flops back and forth more so it is a bit weaker and not as safe at higher rpms, but I don't think u will notice much if any difference and I don't think these slightly shorter rods will at all effect the life of your engine
I agree, but to chime in on terminology, the rod getting closer to 90 degrees when optimum fuel combustion takes place is known also as rod angularity. It's one of the ways they got more torque out of the type 4 air-cooled engine, along with a longer stroke crankshaft. But you are right about rod angularity limiting your top end and red-line, since it increases your reciprocating assembly speed. Pistons move faster in their bores and have a little more side loading on the cylinders. Overall, tough, I wouldn't worry about it at all as these engines can take the punishment in stock form (obviously). You might also gain a little more torque out of the setup which would help you on those hills.
And boost helps too. ;)
P.S. On your trans, what trans are you running? I have been told by one Vanagon enthusiast the air cooled transmission actually had higher FD/high gear combo. IDK, but feel free to chime in on that.
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Thanks for the giggles TrevOrbr - I'm not worried about it really - just wondering if any torque curves existed for the two different rod length engines.
I agree with you and he also agreed about the crank journal offset being obviously the most significant to torque - I mentioned it as well. He was pointing out that the torque curve will be higher in the RPM curve - but won't torque (the peak of the curve) be lower with the shorter stock rods? It's not that there's more torque or less torque - just torque in a different place.
My van has the gasser four speed - what they refer to as the six-rib. I just went through it last fall. I also have 16" rims and the tallest tires I could stuff into the wheel wells (I'll post the size and final ratios tomorrow from the shop computer).
It seems to run around 3850 at 70-75 MPH on the speedo which is off due to the tire size. I was running 15 lbs on a K14 with the fuel screw in a bit. It ran at 10 most of the time and 15 plenty (Cal mountains).
What I'm hoping to hear is that the shorter rods will be better (even if I can't tell) for this application - not worse. I guess it a bear sh**t/woods sort of thing. One thing for sure, the stock pistons have more mass in them than the ones with the smaller pins. That should help handle a bit more heat than it did.
OK, I've proof read this till I confused myself ;D ;D ;D - oh well, I'm posting it anyways!
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i think power wise u would theoretically gain power through out the whole rpm range the down side is higher risk of failure, but there are a million other factors, which is why i think any noticeable difference will be minimal once the engines all back together
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As promised, here are my Vanagon gasser tranny ratios (1st to 4th):
17.2746 9.4142 5.6211 3.89364
My tires are 215/65R16
Revolutions per mile = 724 which should put the RPM's at 3500 at 74 MPH.
These numbers come from a Vanagon transmission ratio calculator I downloaded.
(Actual reality may differ)
I download the chart (excel) here http://www.google.com/url?sa=t&rct=j&q=vanagon%20transmission%20ratio%20chart&source=web&cd=1&sqi=2&ved=0CDcQFjAA&url=http%3A%2F%2Fmembers.shaw.ca%2Fvwdiesel%2FVanagonTransRatios.xls&ei=U2CuUMGMI6q22gXdxIHoAw&usg=AFQjCNG-1BX8XdmTAsHWdzGLZif-OtDcnQ (http://www.google.com/url?sa=t&rct=j&q=vanagon%20transmission%20ratio%20chart&source=web&cd=1&sqi=2&ved=0CDcQFjAA&url=http%3A%2F%2Fmembers.shaw.ca%2Fvwdiesel%2FVanagonTransRatios.xls&ei=U2CuUMGMI6q22gXdxIHoAw&usg=AFQjCNG-1BX8XdmTAsHWdzGLZif-OtDcnQ)