1.5TD Pumps do exist (The 1.5TD project)

[saurkraut]

Looks like boreing out the small end of the 1.5 rods to accept 1.6TD pins might be an option.

The 1.6TD rod is on the left 1.5 rod on the right:



The 1.6TD rod has a thicker fillet on the base of the small end:



I have to remove the bushings and make some measurements yet.  But looks like I'll be useing 1.6TD pistons and block with the 1.5 rods and crank.

[blkboostedtruck]

thats wierd Karl! seems that the 1.5 rod is longer then the 1.6?
i thought it was the other way around?
Duane

[saurkraut]

1.6 stroke: 86.4mm

1.5 stroke: 80.0mm

the 1.5 rods are longer by 6.4mm or 0.252".

Here's some longer rod/piston dwell stuff from a couple different sources on the internets.  Its the main reason that I'm putzing with a 1.5.

"A longer connecting rod gives more piston dwell at top dead center, and at bottom dead center. The advantage at top dead center is that ignition timing can be retarded because the increased long rod piston dwell gives more time for the mixture to be burned more completely in a smaller combustion chamber volume, closer to top dead center. This means the burning mixture has to work less against itself and the still rising piston on the compression stroke because the ignition fires before top dead center."

"Piston Dwell Time and Piston Speed
An often overlooked factor has to do with piston dwell time, the amount of time the piston remains at the top and bottom of the stroke. Increased rod length yields a longer piston dwell time. Longer dwell time allows for better flow of combustion and exhaust gases since the piston accelerates slower in the transition between "up" and "down" strokes. Intake gases have a longer time to enter the cylinder while exhaust gases are given more time to escape. This translates into more natural torque over a longer range of rpm."

"An engine's rod/stroke ratio is its connecting rod length divided by its stroke and is expressed in ratio form like 1.68:1 or something like that. Generally speaking, a higher ratio is better than a lower one. You should also know that a rod's length is proportional to its angularity within the cylinder, which means as rod length increases, the side load of the piston against the cylinder wall decreases - a good thing. Engines with low rod/stroke ratios - short rods or large strokes confined to low deck heights - are prone to premature piston skirt or cylinder wall wear because of their harsh angle and often increased piston speeds. Engines with higher rod/stroke ratios are generally high-rpm friendly."

"Piston Acceleration / DecelerationReducing piston acceleration / deceleration from and toward TDC will reduce tensile loading of the rod, the number 1 cause of rod failure. Again this can be done by using longer rods. E.g. [TODO]"

[Rabbit on Roids]

ok, has anyone payed attention to the pistons yet? 1.5 pistons are taller from the wrist pin hole to the top of the piston. 1.6 pistons have the hole closer to the top, so it will have ALOT less compression if someone actually gets 1.6 pistons to fit on 1.5 rods.

[saurkraut]

Thanks for the heads up.

Do you have one of each handy to do a side by side photo, or can you measure.

I have a 1.6TD piston with a busted ring land that I got from Dr. Diesel.  I'll have to pull the current 1.5 engine appart and look at the difference.

There is a big difference in piston pin diameter.  Is the pin diameter difference the difference your seeing as pin to crown height?

[Rabbit on Roids]

ill go down to my grandpas today and dig through the pile of dead engines and see if i cant find a piston from each kind of motor for a comparison. but the difference is visible when you put them side by side. its less than an 8th inch, but its still different. only reason i know this, is cause the current engine in my rabbit had a bent(rather crushed) rod and broken piston, and i didnt feel like doing a complete rebuild or spending any money, so i went and grabbed a used piston and rod from my grandpa, got home, didnt fit.

[drrtybyl]

Here's one of the non-turbo 1.6 pistons (left) that came with my 1.6TD block (separately) next to a piston from my 1.5 (right):

[saurkraut]

Well, looks like the next step is to get a 1.5 piston and measure the actual pin height difference between the 1.5 piston and the 1.6TD piston, and then get the block decked when its getting bored to first over.

Anybody have junk a 1.5 piston laying around so i don't have to take the engine appart?

[saurkraut]

Good point.

I really need to make some measurements befor any chips fly.  We know for sure there is a .252" stroke difference, but everyhting else is up in the air.

The main bearing journal to deck height should be the same for both the 1.6 and 1.5 blocks.  I just have to measure the 1.6 rods and piston, the 1.5 rods and piston, and then figure out what needs to be cut/bored to make it work.

I have everything but a 1.5 piston, except for the four in the cracked block, in the car.

[drrtybyl]

EDIT:

Looks like the pin hole diameters are 22.5mm (1.6L) vs. 24mm (1.5L).  Distance from the bottom oil ring groove to top of the pin hole on each appears to be 1.25mm (1.6L) vs. 4mm (1.5L).

Interested in drilling some holes in your dead 1.5 block to confirm that oil squirter passages line up similarly between the 1.5 and 1.6 blocks?  

[saurkraut]

The distance from the top of the wrist pin hole to the crown on a 1.5 piston would be usefull.

I can probably try drilling a couple of holes in the cracked 1.5 block, but thats a few months away.

[Rabbit on Roids]

the distance is 1.305" from top of wrist pin hole to piston crown on a 1.5.

[saurkraut]

Just received lightened balanced 1.9 rods from Dr. Diesel:




I have a fresh overbored 1.6TD block with new pistons and an extra 1.5 crank standing by.  Time to bolt stuff togather and do some measurements.  By rough calculations, .063" has to come off of the top of the pistons.  So I need to verify actual protrusion, and go from there.  Oh yah, I got to come up with a bushing deal for the wrist pin end of the 1.9 rods....

[Turbinepowered]

EDIT:

Looks like the pin hole diameters are 22.5mm (1.6L) vs. 24mm (1.5L).  Distance from the bottom oil ring groove to top of the pin hole on each appears to be 1.25mm (1.6L) vs. 4mm (1.5L).

Interested in drilling some holes in your dead 1.5 block to confirm that oil squirter passages line up similarly between the 1.5 and 1.6 blocks?  

Bump from the dead here, but what?

You're saying a 1.6 diesel has a smaller wrist pin than the 1.5 diesel? That's weird.

[Rabbit on Roids]

i really dont think they are smaller. i think the 1.5/6's have the same size wrist pins. but im not sure, i will check. and whatever happened to all the activity on here? am i going to have to revive this and start building my 1.5 td?