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#45
by
RabbitJockey
on 02 Jun, 2008 17:07
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so did it run better with the pistons in backwards or forwards? haha. one mistake that i can't stop giggling about. but no worries, i would easily do the same thing
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#46
by
saurkraut
on 03 Jun, 2008 06:11
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Yah, I still can't believe I had that major brain fart. I had the rods on the pistons right, but forked it up putting them in the block.
But actually, yes, it did run better with the pistons in backwards. I think I had it up to 80+ mph on a multi-car pass with more to go, on the first head gasket. It was also the thickest gasket, so I think the piston orientation had very little impact because of the excessivly thick squish band. (five notch Vrs. two notch)
I think what happened is that four head gasket changes, in rapid succession, were too much for the block.
I wonder if all the 11mm blocks have stress cracks right out of the factory from the pittifully short thread engaugement length of the 11mm fasteners. I'll try to take a photo to show how bad it is. Its not the 1mm difference in diameter, its the length.
I'd really like to go with all 1.5 stuff, but finding a brand new block that has never had a head torqued to it is virtually impossible.
Also, from my experiments, the piston cooling jets are a band aid for a too small exhaust, and too low boost pressure on the original engine design. With a little pump adjustment, and the spruce thermocouple, I could have easily adjusted this thing to stomp the beejeepers out of a stock 1.6td rabbit, and never go over 1200° F.
All thing being equal, and given a choice of wether to have cooling jets or not, its definatly better to have them. But they are not a neccessity for drastically improved performance.
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#47
by
FWD.MOTION
on 13 Jun, 2008 16:27
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very informative info youve been reaserching
Im very inpressed and im about to drop the turbo onto my n/a 1.5
good call about the largly undersized exhaust I think I agree....
we'll soon find out.
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#48
by
Green79
on 24 Sep, 2008 20:04
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So where and how did the 1.5 block crack exactly? Any photos? I've heard that the 1.6 blocks have strengthening ribs, but I'm curious to see where your 1.5 block failed... if it was in the same place. Had your block seen many head removals/retorques prior to your project, when you started using the studs (if the history is at all known)?
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#49
by
saurkraut
on 25 Sep, 2008 06:06
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I haven't torn the engine down yet. Probably get to it in a month or so.
My current focus is making a
1.9 mechanical head and installing it in my '79, and souping up my Audi 5000TQW.
On this engine, I went to studs after one of the original six point socket head bolts stopped going up on torque when I was putting this basket case motor back together.
I truly suspect all 11mm blocks have one 'hit' on them from the first torquing at the factory. The insertion length of the both OEM hex head bolts, and the stretch bolts is woefully inadequate, and probably damages the block the first time they're torqued.
As a result, all the 1.5 stuff is going into a 12mm block. Which also means I'll have some 11mm Raceware head studs up for grabs too.
I have to get the 1.5 rods next to the 1.6 rods and see if I can overcome the piston pin difference issue. As far as I can tell, first over size 1.5 pistons are rare to non existent. So I can't just punch out a block to the first oversize and toss in the 1.5 stuff. I have some figuring to do before I proceed.
But rest assured, the 1.5TD will live again. Maybe in a more period correct chassis. :wink:
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#50
by
arb
on 25 Sep, 2008 08:11
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Since the valves did not contact the pistons when they were in backwards, it begs the question: Are there flat top pistons for our 1.6L ? This would give a little higher compression ratio and therefore slightly higher efficiency.
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#51
by
saurkraut
on 25 Sep, 2008 08:54
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The pattern machined into the piston is not for valve relief. Its for flame travel comming out of the swirl chamber.
These things probably have huge cranking losses already from the 23:1 compression ratio. The 23:1 compression ratio was selected for very low temperature un-assisted starts. There is a SAE paper somewhere that discuss the selection for cold starts only while acknowledging that it was a compromise that had a negative effect on other performance parameters.
Higher compression is not the answer.
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#52
by
RabbitJockey
on 27 Sep, 2008 09:16
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Since the valves did not contact the pistons when they were in backwards, it begs the question: Are there flat top pistons for our 1.6L ? This would give a little higher compression ratio and therefore slightly higher efficiency.
you know that these engines pistons don't have valve reliefs right? i think the most effecient cr for our cars is something like 16 or 17, i forget where i read that tho.
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#53
by
8v-of-fury
on 27 Sep, 2008 09:56
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1.5 TD?!?!!? And your squeeeezin mad power outta that little bad boy!
MAJOR PROPS! Love your car, looks awesome in the last snow pic there
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#54
by
dirtnut99
on 25 Nov, 2008 23:20
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Hey there do you still have the studs from the 1.5?? How much do you want for them and to ship them to 98520?? I am going to rering my 1.5 hopefully if the cylinders work out as planned.
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#55
by
jtanguay
on 25 Nov, 2008 23:32
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Since the valves did not contact the pistons when they were in backwards, it begs the question: Are there flat top pistons for our 1.6L ? This would give a little higher compression ratio and therefore slightly higher efficiency.
you know that these engines pistons don't have valve reliefs right? i think the most effecient cr for our cars is something like 16 or 17, i forget where i read that tho.
some of the newer diesels have CR as low as 16-18
but as stated before, the higher CR is mainly for cold starting. Mercedes created a variable CR engine that could run on gasoline or diesel... now that thing would ROCK!!! dial up the CR for that -20C start, then lower it once its all nice and warmed up for some good performance :twisted: oh yea and it also uses gasoline at higher rpm's :roll: :lol:
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#56
by
Typrus
on 26 Nov, 2008 23:27
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SWEET!
That'd definitely make the 1.5L IDI Kart a little more exciting. lol
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#57
by
arb
on 27 Nov, 2008 08:57
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Since the valves did not contact the pistons when they were in backwards, it begs the question: Are there flat top pistons for our 1.6L ? This would give a little higher compression ratio and therefore slightly higher efficiency.
you know that these engines pistons don't have valve reliefs right? i think the most effecient cr for our cars is something like 16 or 17, i forget where i read that tho.
Mercedes created a variable CR engine that could run on gasoline or diesel...
Have you got a link for that ? I googled and could not find it in the sea of M-B stuff. Sounds very interesting.... John Deere did a lot of research on the Wankel rotary engine. They developed a SCORE - Stratified Charge Omnivorous Rotary Engine. Would run on just about anything. Too bad they didn't take it to production. You fill up with what ever is cheapest. I bet it made the governments a little crazy as they would not have been able to social engineer the with fuel tax rates.
http://www.rotaryeng.net/Stratfied-charge-rotary.pdf
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#58
by
drrtybyl
on 02 Dec, 2008 14:26
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I used Audi80's idea and made an insert for the front oil drain hole in the gasket from a rubber gasket for the oil fill cap. With the 1.5 or 1.6 head, there was no leaks. Granted, the run time with the 1.6 head was brief, but it didn't leak.
Nope, JB Weld is not the best option. Its quick and dirty, and probably failure prone. The best option is welding in filler, and machining it flat again. Since I'm building a different block now, I'll probably do the weld thing.
Notice any other issues with the 1.6TD head? I've pulled everything (turbo, manifolds, BOV, pump, etc.) off of an '84 Quantum with the same goal for my 1.5..
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#59
by
saurkraut
on 03 Dec, 2008 06:19
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Notice any other issues with the 1.6TD head? I've pulled everything (turbo, manifolds, BOV, pump, etc.) off of an '84 Quantum with the same goal for my 1.5..
Nope, just the front oil drain. And if i can go to a 12mm TD block, that goes away too. But from what i learned from my 1.9 mechanical head conversion, an aluminum pipe plug from McMaster Carr could be used to down size the 1.6 head front drain hole to work with the 1.5 block. Tap it, screw it flush, and drill it to size.
P/N: 44705K335
Low-Pressure Aluminum Threaded Pipe Fitting 1/2" Pipe Size, Square Socket Plug
In stock at $4.20 Each
