Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

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Fred
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

Oh no! A classic VW style exhaust. There's likely no where good to put it. In the Y at either end of the muffler is probably best, the tips are definitely NOT OK due to reversion. Ideally you'd have a set of extractors and place it in the final merge point ~3ft from the exit.
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Andreas »

I chose a classic exhaust bc this is my wife's car and if there are exhaust parts hanging down much below the body work, she will not be happy. Let's face it, this car is a compromise. My wife wants heat, so I'm left with the heater box exhaust. I don't want to spend $300 x 2 for heater boxes with 1.5" vs 1.25" primaries. Having heater boxes means a more traditional exhaust anyhow. I'm not sure why I'm doing all this work to tell you the truth. I think she would be happier with new paint than EFI. Wait, I KNOW she would be happier. This is sort of an exercise for me and I'd rather not deal with the limitations and maintenance of distributors and carbs. If it were my car, I'd skip the whole Ghia and go straight to this (except with body work):

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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

Fair enough! My advice stands. On one side of the muffler, or the other, seem to be the only good places to put it. You could run two of them if you are paranoid. One is likely enough, though, if your hardware is good.
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Andreas »

Sounds good. I might be welding it up after I have it on the car. I tried to get an adapter for my 2 manifold flow regulator for my argon, but didn't have any luck. I might see how it goes anyway.

I hope I don't come across like a d*ck. I don't mean to. :D I appreciate the feedback and ideas. Usually I've researched and thought things through, but I do miss things! ...and this is my first time doing a large car project like this.

I mounted the CHT sensor under a head bolt. It felt a little iffy putting it under the spark plug. There will likely be some cooling as there are fins close to it, but it is solid metal between the spark plug hole and the sensor. There are no real places to drill and tap a hole that won't end up close to a fin so I actually think this is the best spot....and happens to be the easiest! Good enough?

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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

You don't come across like a dick, that's usually my job! I hope I'm failing. :-D

That "CHT" sensor, what type is it? do you have data for it? Is that orange wire the ground for it? Or the signal wire? Is it a one wire or two wire sensor? If it's one wire, you'll have to do an epic job with your wiring to keep the noise out of it.

And holy guacamole, those plugs are well off on an angle with each other :-D As long as they seal, and don't leave anything sharp hanging around in the combustion chamber to auto-ignite, should be fine.
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Andreas »

I've read a couple threads that you must have needed a coffee or a nap, but we have all had those days. ;) You are very helpful and I appreciate that.

The CHT is a two wire thermocouple. It has eyelet connections with small bolts through them. It is from Dakota Digital. I can email them to see if they will tell me the type, or can look at the mV output vs temp.

The spark plug is not that off. The lens' fisheye effect makes it look REALLY off. I estimate it is 5 degrees off, which is more than I want, but what can you do? I drilled by hand with a slightly larger bit than the hole and usually the drill naturally aligns itself with the hole, but not this time. :mad:

I finished the rear brakes.

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I'm finished with the intake for now. I had to turn the throttle body upside down to get the throttle cable to match up. I had forgotten about that and had to do some modifications. The TB ended up more on one side than the other....that is how it is stock too, but not quite this much. Not much of a plenum, so we will see how that works. :indiff: Oh, and I guess I'm supposed to put a line to the crankcase vent too. Forgot about that too!

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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

OK, you'll be the first to use a thermocouple (probably K type) as CHT. It'll require an extra circuit, and great care, as well as a specific lookup curve, though I may have one of those for you in my reflow oven controller branch. Aside from the circuitry, these things tend to be pretty noisy, which you must minimise. Good luck!

You'll need to ditch the pull up on the input, too.
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

The other option is to abandon ship with the thermocouple and fit a standard thermistor coolant sensor of some type to the head. There was a thread about this, somewhere. Let me try to find it... viewtopic.php?f=54&t=2063 read both pages, some good info, and I was onto it enough to cache an image or two :-)
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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Andreas »

Ok, so ditch the thermocouple that I spent more time and money than I wanted on it. :lol2:

I have a water coolant sensor that I was going to put in for oil temp, but will use it somehow on the head. I was planning on installing the engine tomorrow so this throws a wrench in the works -- especially since I have to put outside everything that is under the car....and it is supposed to rain around noon tomorrow! I guess we will see.

I spent WAY too much time running a fuel line from the front to the back. I had to climb the lift and crawl through the window (the lift doesn't allow the door to open) about 20 times. There was no way to do it myself. I called all around and finally an hour later a neighbor helped me for probably 45 minutes before we got the damn thing installed. It was probably 3+ hours for me. It was brutal. I read threads where they put it in "in 10 minutes." :mad:

I went crazy with the black spray paint in the engine bay. It looks much better.

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Re: Jaguar 0.7 alpha build for 1972 VW Karmann Ghia

Post by Fred »

Well, you don't have to ditch it, but if you want to use it, there is further work to do, and it'll be tricky to get it working 100% right. I had trouble just getting it working close to right on the bench with my oven setup.

If you read the thread, both pages, properly, you'd also see that normal thermistors are near short at higher temperatures. I think ford units generally have a high resistance that might be suitable. There was one linked from that thread, but I'm unsure that it's unique, I thought many ford units had similar curves.

With coolant you're looking at 85-100C fully warmed up, maybe a fraction over 100 being beaten on with insufficient cooling. Your head will run a lot hotter than that, at which point the precision of the thermistor will be flat on its face. If you did use a forward one, you'd want to bias it differently to normal to get the best from it at the higher temperature range you will see. Not sure how hot air cooled heads get, but that's something you can easily find out.
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