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todd914's Avatar
 
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how much hp gain??

I have a 72 1.7 motor that I am going to be rebuilding. I have a few questions about what to do to get a stock 1.7 to put out 100-110 hp using the stock FI that will stay reliable as a daily driver. I would like to get some slip in 96mm pistons/cylinders and port/polish the heads. Should I stay stock or go stainless valves? How much of a hp gain will I notice with the 96's? Is there a mild cam that will have a good broad range that you guys would recommend? I dont want a rough idle but something that will give me more power throughout the rpm range. The motor I have I believe puts out 80hp. I would like to be around the 100-110 hp range. Any ideas would be appreciated. Thanx in advance!!
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Old 11-22-2002, 07:12 PM
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Todd, go to this post. It'll tell ya alot.
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Old 11-22-2002, 10:41 PM
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IMHO the best bang for your buck would be to buy a strong used 2.0, make sure it is running perfectly, and maybe throw a header and good muffler on it. Then sell/trade your 1.7 core for whatever you can get.

That will get you to 90-110 reliable, easy hp for probably < $2K. Good luck rebuilding a 1.7 to 110hp for anywhere near that
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Old 11-22-2002, 10:50 PM
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Going to be tough. The P&Cs are going to give you maybe 6 or 7 hp. More radical cams tend not to like the fuel injection (or vice versa), although some say webcam 73 will work okay (ask Jake Raby).

D-jet tends not to like too many changes. L-jet Fuel Injection seems to be more tolerant. (i.e., D-jet may require more tweaking).

You might pick up a few HP with a free flowing exhaust (try Tangerine Racing), but overall, you're probably only going to get max 95 to 100 HP out of the 1.7. The limiting factor will be the smaller valve sizes in the 1.7 Heads. They are probably the worst of the 914 head designs.

Switching to 1.8L heads may help for a few HP as they have bigger valves and tend to be stronger.

Stick with the sodium filled exhaust valves if you can. They disapate the heat better. You can get bigger stainless valves (=$$$)

Larger valves, porting and polishing are good for a few HP. = ($$$)

Bumping up your compression by flycutting the heads sometimes leads to geometry problems with the pushrods. = ($$$)

For the hastle and what you will probably spend, you may want to consider looking for a good 2.0L motor, adding Euro Pistons and Cylinders, a hotter cam, and carbs, and you'll easily get to 100-100 HP!

Stock 1.7 - 80 HP
96 MM P&Cs - +6 HP
Hotter Cam - + 4 HP
Free flow exhaust - +5 HP
Port, polish, - +5 HP

Lots of $$$$ for about the same output of a FI Euro-pistoned 2.0L...

Good luck.. Search the archives on this board for similar questions.

Regards,
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Old 11-22-2002, 11:01 PM
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Well I forgot to mention that I am going to go with bigger valves in the heads. I have heard good things about the titanium valves but I've never used them. I had a 2l before and wanna try and stay away from them cause they are more pricey when stuff breaks
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Old 11-23-2002, 12:27 AM
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FWIW, years ago (before they had sites like this) I rebuilt my 1.7 stock except for 93mm p/c. I could feel the difference in power in my day to day driving. The 96's should be even better. I think you can adjust out your MPS to make the 1.7 system work, or put in 2.0 injectors and adjust it in.

Jake's got me sold on the webcam, says it will run cooler. We Texans need to keep that in mind. I think a73 or 86 would work with the fuel injection.

The hardest part for me is deciding what to do, with all the possibilities. Good Luck with it.

PD
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Old 11-23-2002, 07:26 AM
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i had a stroked mark stephens motor about 12 years ago. it was wicked. ( 75x96 with dels/bursch/mild cam ). very temprimantal, but fun on the pipe. a stock 74 2.0 fi with euro p&c is your best bet.
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Old 11-23-2002, 09:02 AM
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A set of 96s and some headwork is good for about 15 Ponies.....according to the CR and cam they are mached to....are you using stock EFI?
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Old 11-23-2002, 11:51 AM
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Yes I am going to be using the stock d-jet.
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Old 11-23-2002, 12:51 PM
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You will be on the brink of safely feeding the engine with the stock system....does it have a stock cam?
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Old 11-23-2002, 12:53 PM
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Yes, what cam should I use to even it all out? I would love to go hydro but I hear you hate em. What exactly are the problem points about this switch. I have used them for years without problems.
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Old 11-23-2002, 12:55 PM
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The "D" jet system really hates hydros, as the events are somewhat delayed...

exploded lifters, and years of problems, as well as increased neglect from owners thinking their valve never need to be adjusted with hudros makes me dislike them. They also always have contact with the lobes and they wear like mad, atleast 40% faster than a solid lifter, inmmy experience... I go over the differences in my TIV engine rebuild video.

I would use a web 73 in that engine, and try to stay around 8:1 CR static according to your altitude and climate.
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Old 11-23-2002, 12:58 PM
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Todd,

I'm going sing along with the rest here. You're best bet for the money is going to be the 2.0L with FI. If you're willing to do the work yourself, the prices really aren't that far off the 1.7/1.8.

And you will really notice the difference!

Enjoy.
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Old 11-23-2002, 02:49 PM
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Its great to rebuild a motor to exactly what you want, like using the 1.7 crank and rods with 96's. If thats the experience you want, great.
But it is way cheaper to get a good used 2.0L complete with FI for around $1000 to 1500. There is your 95hp stock!
The 1.7L rebuild/buildup is going to cost DOUBLE that so you are money ahead.
Look for a 2.0L that is coming out of a car that a six is going into. Heck, they may even throw is the SSI HE's and muffler just to get rid of it and get some cash.
Geoff
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Old 11-23-2002, 03:25 PM
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Anybody out there wanna trade 2 - 1.7's for 2.0?
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Old 11-23-2002, 05:14 PM
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Sure, I'll take that trade! I think I know where I can get my hands on a couple of 1.7s, and I could use that spare 2.0... Oh, you mean the other way around, huh?

BTW, just about anyone who says "XX mods will give you YY horsepower" is talking out their a**. Most especially me!! An engine is a system, and all of the parts of the system will affect the rest of it. And the power curve is the product of the system as a whole. A great cam, nicely-flowing heads, and a top-notch induction system can still give you crappy power if you have little tiny valves and a nasty restrictive exhaust... And there are a lot of little things that can give you some power here and there, or cost you if they are not done or are done wrong. There are so many variables that it's really hard to do anything but hand-wave about power numbers.

Except, of course, when you have already built the engine and ran it on a dyno--then you can say "This engine built with these parts and those techniques gave me that kind of power." And if you've kept careful notes about exactly what you did, you ought to be able to reproduce those results. Usually.

But changing one thing can have unexpectedly large results (for good or bad) sometimes. As Raby has said on other forums, "It's all in the combination!"

--DD
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Old 11-23-2002, 05:39 PM
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Ya - ya... I know! As soon as I hit the submit button I knew what I'd said..... and yes, Dave is right, it's the other way around
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Old 11-23-2002, 10:18 PM
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