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Engine Specific Info and Questions => IDI Engine => Topic started by: tomsdubwerks on May 30, 2012, 03:30:18 pm
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After stripping my GTD project engine and finding two bent rods I'm wondering how much boost the stock rods will handle?
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After stripping my GTD project engine and finding two bent rods I'm wondering how much boost the stock rods will handle?
more than the head will take..
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Probably bent from the coolant pouring into your cylinders.
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Probably bent from the coolant pouring into your cylinders.
or very bad valve contact..
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Probably bent from the coolant pouring into your cylinders.
or very bad valve contact..
Coolant causing hydraulic lock was on my mind given the state of the gasket. Valves don't appear to have touched the pistons but will get a good once over to be sure. I wasn't going to rule out it it running away on its own engine oil due to the twisted and collapsed oil return and the amount of oil in the turbo itself.
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Also stumbled across a thread claiming that the stock rods will take 290ft/lbs of torque without issue. They certainly look nice and strong but I'm used to petrol engine ones. I should imagine 20-25psi of boost is not a problem for them?
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The worry-free solution i have chosen:
(http://rosten-performance.com/images/rods/h_beam_rod_vwaudi_16td.jpg)
http://rosten-performance.com/
As a general rule I would say if you are going to run a wastegated turbo, stock is good. A VNT with active vane control, H-beam rods (and a block girdle) may be needed.
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Also stumbled across a thread claiming that the stock rods will take 290ft/lbs of torque without issue. They certainly look nice and strong but I'm used to petrol engine ones. I should imagine 20-25psi of boost is not a problem for them?
i ran north of 35psi (closer to 40psi) to a 1.5D engine, before the head let go..
i tell you, the RODS are not the weak point. the head is. the bottom end will take whatever you throw at it.
hell, i was making 20psi around 2500 revs the other day, ~half throttle or so.. and my engine still runs. they almost never see those kinda boost pressures down that low..
my experience is with VNT turbos tho, and they make lots of boost down low.. conventional turbos usually run more restricted flow tho, so dont expect those numbers with a conventional turbo..
so, again.. the HEAD is the weak point of IDI engines.. not the bottom end. the rods will compress anything that can be compressed..
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I bent my rods and was only pushing 30 to 35psi with my twin setup. it didn't like to run too well at an idle. tore it down and found 3 rods were bent. Two were sitting below the deck. I think it had to do with my intake setup but still possible to bend the rods. Now I am running Pauter X beams.
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When they bent, did you have to scrap the block, pistions, and rings, or did you just put new rods and rod bearings in the same bore and all was well? I have been thinking of upgrading rods, but money is money :D
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i ran north of 35psi (closer to 40psi) to a 1.5D engine, before the head let go..
i tell you, the RODS are not the weak point. the head is. the bottom end will take whatever you throw at it.
hell, i was making 20psi around 2500 revs the other day, ~half throttle or so.. and my engine still runs. they almost never see those kinda boost pressures down that low..
my experience is with VNT turbos tho, and they make lots of boost down low.. conventional turbos usually run more restricted flow tho, so dont expect those numbers with a conventional turbo..
so, again.. the HEAD is the weak point of IDI engines.. not the bottom end. the rods will compress anything that can be compressed..
There is a lot more factors to Peak Cylinder Pressure than just boost. Fuel and boost it like crazy on low RPMs and see if your rods can take the beating. ;)
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Those Rosten rods look awesome. Thanks guys I'll be running a conventional turbo or maybe an Eaton supercharger with sensible boost levels for daily reliability. Fairly confidant stock will be fine for me after reading your experiences. My spare N/A gave up it's crank and roads last night for the TD. Just need to clean them up and measure up.
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When they bent, did you have to scrap the block, pistions, and rings, or did you just put new rods and rod bearings in the same bore and all was well? I have been thinking of upgrading rods, but money is money :D
I just put new rods in and called it good. I even used the old rod bearings. I really wouldn't call them old. They only had maybe a 1000 miles on them. I checked them over and platsigauge them in a few spots and all was well. Still running good till this day. I'd say I have about 7,000 to 8,000 on it now and I still beat that poor engine up.