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Opeler
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Discussion Starter · #1 ·
What would the inprovement in horsepower be between a stock intake and a ported one? I recently bought a 72 Gt and have a freind who drag races a GT in comp L/A NHRA and I am sure he would know what to do with it. Where else could I pick up a few horses, not sure if the motor has the low compression pistons. What is in a header? I would like to pick up maybe 30, motor has 65.5 hp. now. Would anyone have an intake they would like to sell? Thanks, Dwight
 

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Porting the intake is easy!

If you have a air compressor and dye grinder (or dremmel tool) do a search here, click on search at the upper right and type in porting intake or just intake manifold. Check out performance modifications as well in your search, think you'll be lucky to pull another 10-12 hp with just bolt on mods IE: Weber carb, header, porting, electronic ignition and stock 75 Fuel Injection (if you can peice a system together).

Now you'd like to get another 30 HP, :rolleyes: Who wouldn't but you'll need to do more than porting the intake, try flat top pistons (72 are dished) mild cam and fuel injection with a 75 manta Sprint exhaust or header. (header is 4 pipes into one off the engine head). and maybe get close to 30 hp. gain
this would mean a engine rebuild to change the pistons!

No easy way! Nor Cheap either! :(

Regards,
Rick
 

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Opel Tinkerer and Rescuer
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But consider this, the motor starts at 65 HP, so a 12-15 jump is 20-25% jump in horsepower.. !

But the biggest HP improvment is a set of 2.0L or 1.9L flat top pistons. If you dont change the pistons from the low compression ones, nothing you do will get you a drastic improvement..
 

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Opeler
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Discussion Starter · #4 ·
Forgot to mention the 65 HP is at the rear wheels. It has been suggested that the motor could have flat top pistons, is it possible to check without removing the head?
 

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OPEL-LESS!!!
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pull the spark plugs out and get a little pen light or a small light you can stick inside the spark plug hole. if you just see 2 valve reliefs, your lucky, see a big half circle like shape, john the rest of us.
 

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Opeler
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Discussion Starter · #6 ·
The car is still 2100 miles away. Can't wait to get it home. Thought I would do some homework while I wait. Thought of at least getting another intake, if they are not to expensive, sent with the car. I have in my corner an engine builder with a 160 cubic inch motor in his GT that puts out close to 400HP, but knows nothing about a 1.9.
 

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If the motor has never been apart look at the serial # on the block. If it starts and ends with * then your chances are extremely good.
 

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Opeler
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Discussion Starter · #8 ·
I will do a search to see where to look for the ID. What is a reasonable price to pay for an intake and maybe even a head?
Thanks, Dwight
 

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opel assimilated
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I just checked the #s on the block of Dwights/Shawns car. The # is *19S-0946063* So it does have the astrisks, but what does that mean? Does it mean it has flat top?
 

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Motor serial # is between #2 and #3 cylinders on the block just below head level. As far as stock intakes the price is pretty low, for a head it varies by year. Early years are worth more in my opinion.
 

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Flipper, it meant it did originally. If it has been rebuilt you can never know. Look at the color of the motor too. Semigloss black is another clue as to originality. Any good or reasonable rebuild includes a hot tank of the block that strips the paint. What color it was repainted is a sure sign. Painted oil pan is another give away it's been rebuilt if it's aluminum. I'm not sure which pan to look for. Liz and Jarrel could tell you on that.
 

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The 73 that I sold to joel from Va. had an aluminum pan. The 70 that has the High compression pistons with the double **, before and after the block nos, also has an aluminum pan. My 72 in the 72 has a steel pan. Go figure. My 74 Manta rebuilt with High compression pistons many, many years ago has a steel pan that came with it originally.
The double ** are a start, but like greensmurf20 said "pull the spark plugs out and get a little pen light or a small light you can stick inside the spark plug hole. if you just see 2 valve reliefs, your lucky, see a big half circle like shape it's low compression"
Apparently from what I've seen, parts were added/subtracted and, or replaced as engines were built/rebuilt through the years. So really there appears to be no standard reply that "This is the definitive one".You're in the ballpark though. Confused thoroughly by now? Easiest thing is to do what greensmurf20 said. Sorry I can't be of more help than the above. Jarrell
 

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Opel Tinkerer and Rescuer
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nobody said:
Motor serial # is between #2 and #3 cylinders on the block just below head level. As far as stock intakes the price is pretty low, for a head it varies by year. Early years are worth more in my opinion.
Actually the late models are the ones worth the coin. Due to the EGR connection, etc. they were taller so they flow better and have more room for the plenum mods.

TO quote Bob from his article:

"To start off with, getting the proper core is essential. I say this because there were numerous variations of the 1.9 intake manifold. I've personally seen seven different intakes for the U.S. 1.9's, and a few other European intakes that have made it over the ocean. Unlike most things Opel, the older manifolds are not better than the later smog-style intakes.

Keep away from the old ones, unless the outward appearance is important to you. They can be improved, just not as much and with more work. In fact the later smog intakes are far superior for airflow and even air/fuel distribution. Notably, the older intakes have a pronounced "ramp" at the outer (towards the fender) side of the plenum wall. The plenum is simply the large open area directly beneath the carburetor. The inner side of the plenum wall (towards the valve cover) is more or less vertical.

Besides the casting dates, the easiest way to identify a smog intake is by the presence of three ports or threaded holes in the plenum area. The third port (most have two, some only one) is the true identifying one, as it shows the presence of an EGR system. You'll see this on all 1973 and 1974 intakes, as well as some later 1972 intakes. Many of the 1974 intakes will also have "U.S.A." cast into the bottom of the plenum, albeit inverted. These intakes are my favorite to work with, as I've seen the best results with the least amount of work."


Charles
 

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Charles your right on that, as far as which intake is best to start with. I have just gotten used to carbs you can't look down into I guess.
 

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Opeler
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Discussion Starter · #15 ·
Thanks for the great replies, and thanks Shawn!! Before I ask any more questions, I am going to search this form and Charles " Goin Manta " web site for the answers, except for a couple. Would anyone have a picture of a 3, 2 , and a 1 port intake? How would a good intake and carb compare to a FI system? And has anyone ever built a FI intake manifold? Thanks Dwight
 

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Opel Tinkerer and Rescuer
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For the answer to the last question.. Yes Opel built one, a few in fact. The 1975 Manta has a FI Intake, not to mention FI. I am not sure if it will fit under a GT hood though, I know there is a whole thread on that.

As for my GoinManta site.. the intake article, and others are at http://www.opel-na.com One of these days I will transfer all those old articles over to this website somewhere. Currently dont think I can upload the PDFs.

Charles
 

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Opeler
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Discussion Starter · #17 ·
I know of a person who builds FI intakes for his car (a GT) and has sold a few to racers in competition eliminator, NHRA. Does anyone think there may be a market for such a piece?
 

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theres definately a market for a pre-made FI system, depending on price, i know i'd be interested
 
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