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> 1.7 Engine Build Questions, Need advice on what I should know
Matty900
post Dec 5 2016, 01:29 AM
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My 72 barn find ( http://www.914world.com/bbs2/index.php?sho...=275587&hl= ) is now starting to get a lot of work done so I can hopefully make it to lots of rallies next year. The car Has 50K original miles on a 1.7 that had some work on it previously making it a 1911 with Dlortos on it.
The engine is now torn down for rebuild with a little more power. I would like it to look as stock as possible but would like it to be a sleeper. I am considering 2.0 LTR FI and having everything else built. I am looking for suggestions on what you would do to the engine and why.
Thanks for the help


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McMark
post Dec 5 2016, 08:19 AM
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The standard upgrades are:

1.7/1.8 starting point and you don't want to buy crank/rods/heads: Build a 1911.
2.0 starting point and you don't want to buy crank/rods: Build a 2056.
Any starting point and you're willing to spend some money: Build a 2270.

These are proven combinations that a lot of people run and you can get a lot of help 'designing' the engine and tuning. There are other combinations that come with drawbacks and compromises. Or there are things like forced-induction (turbo/super) but those aren't anything as easy as building a bigger motor.
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Matty900
post Dec 5 2016, 10:25 AM
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QUOTE(McMark @ Dec 5 2016, 06:19 AM) *

The standard upgrades are:

1.7/1.8 starting point and you don't want to buy crank/rods/heads: Build a 1911.
2.0 starting point and you don't want to buy crank/rods: Build a 2056.
Any starting point and you're willing to spend some money: Build a 2270.

These are proven combinations that a lot of people run and you can get a lot of help 'designing' the engine and tuning. There are other combinations that come with drawbacks and compromises. Or there are things like forced-induction (turbo/super) but those aren't anything as easy as building a bigger motor.

Thank you. I would have you build this for me but the guy that I bought the car from has built moters for sandrails for decades and I started with him thinking that I wanted to build a screaming moter that would run on carbs. After riding with Eric Shea for about 900 miles for Red Rocks this year I wanted to do a GT. My thought was with the car getting body work and paint now, why not just set it up now with the oil cooler flairs ect and have the 1.7 built until I can afford a 6. After talking with my brother, he convinced me to go concourse. So now I have an engine torn down for a build, with someone who is capable of doing a good build, but he is not in the 914 community so not the best source for what I should do for concourse correct choices.
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Optimusglen
post Dec 5 2016, 10:34 AM
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I guess I maybe don't know the full meaning of the term, but when I think concourse car, I think of an original car, built to original specifications. Not something that's been cut up for flares with a swapped or modified engine. But again, I'll be the first to admit I sometimes don't know what I'm talking about.

For what it's worth, I've heard the 1911's are pretty dang peppy. That's what mine is, hope to have it driving next Spring. If you build the 1911 you'll probably keep the 1.7 heads/tins/specific bits and make it look the closest to it's original 1.7 setup.
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Dave_Darling
post Dec 5 2016, 02:45 PM
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Your 1911cc with Dells should be about as good as you can easily do. If there's nothing wrong with it, slap it back together and keep driving! Most especially if you are going to do an engine swap in the near to middle future, the cheap and easy way is likely the way to go.

For more power, you're looking at spending money that you won't get back. Either a nice cam and a bit of head work to wake up the 1911, or finding a 71mm crank and rods (and P&Cs) to make the 2-liter's 1971cc displacement, or a 2056cc. But the 2.0 heads are expensive, and your 1.7 heads would need a good bit of work to flow like those do.

If you can find a 2.0 engine complete with FI, that should be mostly a bolt-in. But those can be a bit hard to find with all of the bits on them.

Oh, a good exhaust like the Tangerine Racing header setup should provide a real boost in power; less-expensive headers will provide less of a boost and most mufflers aren't much improvement when using stock heat exchangers.

I do think the best option is freshening up the current motor (if it's apart) and just driving it.

--DD
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Matty900
post Dec 5 2016, 05:55 PM
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QUOTE(Optimusglen @ Dec 5 2016, 08:34 AM) *

I guess I maybe don't know the full meaning of the term, but when I think concourse car, I think of an original car, built to original specifications. Not something that's been cut up for flares with a swapped or modified engine. But again, I'll be the first to admit I sometimes don't know what I'm talking about.

For what it's worth, I've heard the 1911's are pretty dang peppy. That's what mine is, hope to have it driving next Spring. If you build the 1911 you'll probably keep the 1.7 heads/tins/specific bits and make it look the closest to it's original 1.7 setup.

You are correct.
I was flip flopping back and forth on doing a concourse restoration -vs- a GT clone over time.
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Matty900
post Dec 5 2016, 06:20 PM
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QUOTE(Dave_Darling @ Dec 5 2016, 12:45 PM) *

Your 1911cc with Dells should be about as good as you can easily do. If there's nothing wrong with it, slap it back together and keep driving! Most especially if you are going to do an engine swap in the near to middle future, the cheap and easy way is likely the way to go.

For more power, you're looking at spending money that you won't get back. Either a nice cam and a bit of head work to wake up the 1911, or finding a 71mm crank and rods (and P&Cs) to make the 2-liter's 1971cc displacement, or a 2056cc. But the 2.0 heads are expensive, and your 1.7 heads would need a good bit of work to flow like those do.

If you can find a 2.0 engine complete with FI, that should be mostly a bolt-in. But those can be a bit hard to find with all of the bits on them.

Oh, a good exhaust like the Tangerine Racing header setup should provide a real boost in power; less-expensive headers will provide less of a boost and most mufflers aren't much improvement when using stock heat exchangers.

I do think the best option is freshening up the current motor (if it's apart) and just driving it.

--DD

Thanks Dave.
I am going away from the idea of anew engine swap on these cars now. I have 2 other cars that are better suited for engine swapping as they already have body kits on them.
My plan now for this car is" a nice cam and a bit of head work to wake up the 1911, and doing a good bit of work on the 1.7 heads to make them flow.
That being said, I know enough to know what I don't know, so I am trying to learn here. So I will probably ask some dumb questions along the way.
You mentioned "finding a 71mm crank and rods (and P&Cs) to make the 2- liter's 1971cc displacement, or a 2056cc
Do you have any recommendations for these, there seem to be a lot of options.
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McMark
post Dec 5 2016, 08:23 PM
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71mm stroke is stock 2.0.
71mm x 94mm is 1971, which is the stock 2.0 size.
71mm x 96mm is 2056.
Stock 71mm crank and rods are fine for most builds, no need for fancy upgraded components.

If I were you, I'd look at a 1911, with a focus on lightening. Order of 'upgrades' by cost/benefit (in my opinion)

Core 1911 (what you've got now, your starting point)
Lightened flywheel.
New 96mm pistons and cylinders.
2.0 heads.
Valves/springs/retainers/pushrods for high RPM (lighter/stiffer).
Lightened connecting rods.
Lightened pistons.
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Optimusglen
post Dec 6 2016, 07:47 AM
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I believe I've read a post on here by Jake Raby that the 1.7 heads are desirable because the smaller ports increases the velocity. I wish I could find it. Unfortunately the 1.7 heads combustion chamber/spark plug location are not as good as the 2.0 heads.
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McMark
post Dec 6 2016, 08:00 AM
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Glen, you're right about the velocity increase and that can have its advantages in certain engine designs. But it's really an aide to low-rpm power. If you build a bigger motor or a high revving motor those small ports will restrict the upper RPM band.

Like all engine design, it's just about what you want out of your engine.
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Matty900
post Dec 6 2016, 02:00 PM
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QUOTE(McMark @ Dec 5 2016, 06:23 PM) *

71mm stroke is stock 2.0.
71mm x 94mm is 1971, which is the stock 2.0 size.
71mm x 96mm is 2056.
Stock 71mm crank and rods are fine for most builds, no need for fancy upgraded components.

If I were you, I'd look at a 1911, with a focus on lightening. Order of 'upgrades' by cost/benefit (in my opinion)

Core 1911 (what you've got now, your starting point)
Lightened flywheel.
New 96mm pistons and cylinders.
2.0 heads.
Valves/springs/retainers/pushrods for high RPM (lighter/stiffer).
Lightened connecting rods.
Lightened pistons.

What about the cam? I know the PO had already done some work on it. What do I want it to be?
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McMark
post Dec 6 2016, 02:49 PM
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Depends on how far down that list you're going to go. If you lighten everything, it'll rev higher and high revs benefit from more overlap. If you're not going to lighten as much you'll probably be happier with a cam with less overlap for better driveability and easier tuning.
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Jake Raby
post Dec 17 2016, 02:31 PM
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I prefer most things about the 1.7 engine as a foundation for a larger displacement build- especially the crankcase.
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