Low RPM + High boost = Bent rods?

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'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

You mentioned that you have the wideband knock sensor mounted 'as high in the block as possible', might this make distinguishing knock from valve train noise a little harder?
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Re: Low RPM + High boost = Bent rods?

Post by vlad01 »

It's pretty obvious when you hear it, its loud and erratic, not a cyclic pattern like exhaust pulses or valve train noises.
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

I'll post a recording tomorrow if I hear anything worth posting
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

The knock sensor is about at the bottom of the pistons stroke. It was the highest place it could be mounted.
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Re: Low RPM + High boost = Bent rods?

Post by delcowizzid »

The sound of knock travels a long way we bolt the wideband donut sensors on some pretty obscure locations on engines when cars are on the dyno the splat/tic is easy to hear amongst most internal noise even with the valve train slapping away just avoid bolting it close to things with ball bearings they are quite hard to hear it over top of
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

After deliberately increasing timing at light load, you can hear the knock but it's not as loud as I was expecting. Kind of like a metallic clicking, like the noise crayfish make when you go diving. Maybe its louder under boost with more energy? I didn't hear it at high rpm though with the auto box, there's a LOT of background noise/whine. Maybe with some highpass filtering it would be easier to pick up, maybe thats why those ears are nearly $1000?

I think I'll not try push the timing. I'm sure there's a lot of power still on the plate but right now its faster, fun, makes all the right noises, doesn't lean out. I'll foucs on getting the VE table dialed in and work on the VNT controller.

There's no currently available electronic VNT controller on the market. If they proove to be reliable, I'm hoping VNT's find their way into more builds. Full boost at 1500rpm is nuts and a larger A/R is always a good thing.

I'll start a build thread on the 1.8L when I find someone to laser cut me the exhaust manifold
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

That sounds like a great result. How did you sort the injector o-ring drama.
What boost are you seeing currently, anything over the 8.25 psi as before, and at what revs.
How about the switching point from Single fire to Double fire.
Do you get much torque steer?
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Re: Low RPM + High boost = Bent rods?

Post by Gareth »

There's no currently available electronic VNT controller on the market.
What about a remote mounted throttle controller? IIRC BMW's had them?
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

I'm using the original injector with the regulator wound up. at 12.0afr at 8.5psi 5000rpm I think it was around 92% duty. I'm going to make up some shims on the lathe this afternoon to get a few more PSI in the fuel rail, right now I consider it safe. I will be setting the controller to a fixed 9psi upon WOT from 1500rpm up. If it knocks down low I'll adjust to suit. No single/double fire needed.

This motor at 9psi is producing only 10-20HP more than the 1.8L, if tuned correctly. Was it a waste of time? Naahhhhh. At least it makes the noises :-)

torque steer is hard to say. The vector isn't registered so I don't want to take it on the roads. On the graded dirt roads on the farm it kind of follows the camber of the road anyway. I'll move it all over to my registered manual pulsar and put some KM's on it and we'll see. The auto was always sooooo underpowered to drive, I expect the manual will be a lot more fun.
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

BennVenn wrote:I'm using the original injector with the regulator wound up. at 12.0afr at 8.5psi 5000rpm I think it was around 92% duty....No single/double fire needed.
Killed two birds with the one stone haha.
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