How to tell you have a High Compression Engine

[69whitegt]

How do you tell the high compression engine from the regulars? I heard one difference is the ash tray in the car. It will have vinyl on it. Any others??

[saxybiker]

The vinyl on the ash tray is an indicator of a 69 model year (unless it has been switched) The 69 model years and early 70 model years had the high compression engines (unless they have been switched).

Vickie

[69whitegt]

What is the HP on the High Compression engine?

[GTJIM]

Have a look at the engine number stamped on the flat, machined pad on the side of the block. Asterisks each end of the number are used on HI-comp engines.

*19S-XXXXXX* for instance.

If there is only one asterisK at one end of the number it is likely to be Lo-comp.

[Willy_g77]

if all else fails you can take the valve cover off and look at the lifters.. correct me if im wrong.... solid lifters are high comp. and hydraulic lifters are low comp.

[RallyBob]

What is the HP on the High Compression engine?

High compression 1.9:
102 gross hp (pre-'71 US rating system, prior to standardized SAE tests)
90 ps (metric hp rating)
82-85 hp (actual hp at the flywheel for most high compression 1.9's)

Low compression 1.9 (US spec)
78 ps (metric hp rating)
75 hp SAE
62-65 hp (actual hp at the flywheel for most low compression 1.9's)

As you can see, the ratings for these engines are all over the place. The only way to know for sure is with a dyno test. Keep in mind a chassis dyno rating
(power at the wheels) will only be about 82-85% of the SAE flywheel rating.

Bob

[2 Fast 4 U]

In Europe we can see it very simpley, if there is a S behind the 1.6 or 1.9 or what ever engine you have, this is a high compression engine, if there is a N behind there it's a low compression engine and an E stands for injection.
so a 1.9 S is a high compression 1.9 engine,
a 1.9 N is a low compression 1.9 engine,
and a 1.9 E is a fuel injection engine.
maybe it's the same in the US

[spdkilz02]

my motor is a 73, it has the 19S, but no asterisks...and it is a low comp

[2 Fast 4 U]

The only sure way to find out is to mesure the compression with a compression gauge

[hallgeir]

In Europe we can see it very simpley, if there is a S behind the 1.6 or 1.9 or what ever engine you have, this is a high compression engine, if there is a N behind there it's a low compression engine and an E stands for injection.
so a 1.9 S is a high compression 1.9 engine,
a 1.9 N is a low compression 1.9 engine,
and a 1.9 E is a fuel injection engine.
maybe it's the same in the US

Wasn`t the carb also different on N and S engines?

[kwilford]

Moved to the Engine Forum...

In truth, the only way to REALLY tell you have a high compression engine is to look at the pistons. The dished tops are Low Compression (LC, nominally 7.6:1), while the flat tops with two valve reliefs are High Compression (HC, nominally 9.0:1). And you might find some that are Extra High Compression (EHC, as much as 13.0:1) with domed pistons. Chevy 265 pistons (such as Jared and others have installed) are flat tops, but with four valve reliefs (so they can be used on either bank of a V8) and are probably a bit lower CR than OEM style pistons. But maybe with the bigger displacement, the CR is still the same (more swept area, but larger combustion volume).

The easiest way is to remove a spark plug and shine a light through the hole to see the piston top. But that can be hard to see for sure, so if you ever have to remove your head...

From the factory, the year and engine serial number were usually enough. But 35 years later, any number of PO's (Previous Owners) could have installed HC pistons in LC engines, or even vice versa. Heck, one owner here pulled his engine apart for a rebuild to find two LC pistons, and two HC pistons!

[hallgeir]

Moved to the Engine Forum...

Heck, one owner here pulled his engine apart for a rebuild to find two LC pistons, and two HC pistons!

Well, well, as we say here: You gonna hear many things before your ears fall off.

Would it be possible to tell by the way it was running?

[lewdawg]

Keith is exactly right. The only way to tell is to look at the pistons. I have disassembled three engines just recently that by the block number were suppose to be high compression engines...NOT!!! All three had low compression pistons installed. From everything I have read here on the site and the different configurations people are finding leads me to believe there was no standard way of identifying a low compression engine vs a high compression one.

[2 Fast 4 U]

Wasn`t the carb also different on N and S engines?

Yep, the N engines have a single barrel carb, and the S ones have a dubble barrel carb

[pastopel]

Keith is exactly right. The only way to tell is to look at the pistons.

And I know another way of doing it!
http://www.scopes.com/detpages/industrial35.shtml

You can find people using these puppies and other models all over, JM2c

[jeff denton]

One of my three engines was flat top, two of them should have been, and one shouldn't have been. In other words, by the application and codes on the block one of them wasn't what I hoped for. So watch that, these engines are old enough that they've probably been into at least once, right? Lord knows what happens on the way back together.
Wow, the scope system would be neat to have. I don't even want to guess what that costs. My dentist has something like that, sticks a little camera in my mouth and can snap still shots while monitoring on a tv screen. He said it was thirteen thousand dollars...
I think if you were very careful you could stick a long skinny screwdriver in the spark plug hole, with the piston about an inch down, and "feel" the piston top. If you feel a ridge near the edge it is a dished piston. If it feels flat all the way to the wall, it is a flat top.
Has there ever been any kind of a way figured out to tell what the compression ratio is by measuring fluid capacity of the cylinder with the piston all the way down, compared to all the way up? Anybody ever thought about this?

[soybean]

The way I found 3 high comp engines out of 7 I have here, was to pull the spark plugs out and shine a little Zeon light into the hole. Actually I got it into the spark plug hole and shined it around to see the Pistons. It was $9.00 at a local Lowes Store, sorta like Home Depot, etc. Liked it, (light) so much I bought 5.
Keith is correct about POs. '" From the factory, the year and engine serial number were usually enough. But 35 years later, any number of PO's (Previous Owners) could have installed HC pistons in LC engines, or even vice versa. " I did the same thing with my 74 Manta.
Jeff has raised a good good question about fluid capacity of the cylinder. Anyone got an answer? Jarrell

[69whitegt]

So if the number on the block has astrics at both ends, then it came from the factory with high compression pistons????

[baz]

So if the number on the block has astrics at both ends, then it came from the factory with high compression pistons????

yes......

[fredopelgt]

However, one should never be surprised when re-building and Opel Engine.

On various re-builds I have found different pistons in the bore plus crankshaft bearing thicknesses? Saves Money