Any one else surprise by such a high comprssion ratio on a s/c motor
engine specs
Engine Type Inline 4 Cylinder
Displacement
2.0 L
122 CID
RPO
LSJ
Liter (VIN) P
Bore
85.992-86.008 mm
3.3855-3.3861 in
Compression Ratio
9.5:1
Bearing Clearance
0.030-0.063 mm
0.0012-0.0025 in
Bearing Diameter - Inside - Carrier
20.050-20.063 mm
0.7894-0.7899 in
Bearing Diameter - Outside - Carrier
41.975-41.995 mm
1.6526-1.6534 in
Bearing Journal Diameter
20.000-20.020 mm
0.7874-0.7882 in
Bushing Clearance
0.033-0.102 mm
0.0013-0.0040 in
Bushing Diameter - Inside
36.776-36.825 mm
1.4479-1.4498 in
Bushing Journal Diameter
36.723-36.743 mm
1.4458-1.4466 in
End Play
0.100-0.300 mm
0.0020-0.0118 in
Block
Balance Shaft Bearing Bore Diameter - Carrier
42.000-42.016 mm
1.6535-1.6542 in
Balance Shaft Bushing Bore Diameter
40.763-40.776 mm
1.6048-1.6054 in
Crankshaft Main Bearing Bore Diameter
64.068-64.082 mm
2.5224-2.5229 in
Cylinder Bore Diameter
85.992-86.008 mm
3.3855-3.3861 in
Cylinder Bore Out-of-Round - Maximum
0.010 mm
0.0004 in
Cylinder Bore Taper - Maximum
0.010 mm
0.0004 in
Cylinder Head Deck Surface Flatness - Transverse
0.030 mm
0.0012 in
Cylinder Head Deck Surface Flatness - Longitude
0.050 mm
0.002 in
Cylinder Head Deck Surface Flatness - Overall
0.08 mm
0.0031 in
Camshaft
Camshaft End Play
0.040-0.144 mm
0.0016-0.0057 in
Camshaft Journal Diameter
26.935-26.960 mm
1.0604-1.0614 in
Camshaft Thrust Surface
21.000-21.052 mm
0.8268-0.8252 in
Connecting Rod
Connecting Rod Bearing Clearance
0.029-0.069 mm
0.0011-0.0027 in
Connecting Rod Bore Diameter - Bearing End
52.118-52.134 mm
2.0519-2.05252 in
Connecting Rod Bore Diameter - Pin End
20.007-20.021 mm
0.7877-0.7882 in
Connecting Rod Side Clearance
0.070-0.370 mm
0.0028-0.0146 in
Connecting Rod Straightness - Bend - Maximum
0.021 mm
0.0083 in
Connecting Rod Straightness - Twist - Maximum
0.04 mm
0.0157 in
Lubrication System
Oil Pressure - Minimum - @1000 RPM
344.75-551.60 kPa
50-80 psi
Oil Capacity - with or without Filter
5.7L
6.0 quarts
Piston Rings
Piston Ring End Gap - First Compression Ring
0.20-0.40 mm
0.008-0.016 in
Piston Ring End Gap - Second Compression Ring
0.35-0.55 mm
0.014-0.022 in
Piston Ring End Gap - Oil Control Ring - Rails
0.25-0.76 mm
0.010-0.030 in
Piston Ring to Groove Clearance - First Compression Ring
0.04-0.08 mm
0.0015-0.0031 in
Piston Ring to Groove Clearance - Second Compression Ring
0.030-0.069 mm
0.0012-0.0027 in
Piston Ring to Groove Clearance - Oil Control Ring
0.090-0.106 mm
0.0035-0.0042 in
Piston Ring Thickness - First Compression Ring
1.170-1.190 mm
0.0461-0.0469 in
Piston Ring Thickness - Second Compression Ring
1.471-1.490 mm
0.0579-0.0587 in
Piston Ring Thickness - Oil Control Ring - Rail - Maximum
0.43 mm
0.0169 in
Piston Ring Thickness - Oil Control Ring - Spacer
1.574-1.651 mm
0.0620-0.0650 in
Pistons and Pins
Piston - Piston Diameter - @14.5 mm up
85.967-85.982 mm
3.3845-3.3851 in
Piston - Piston Pin Bore Diameter
20.002-20.007 mm
0.07875-0.7877 in
Piston - Piston Ring Grove Width - Top
1.23-1.25 mm
0.0484-0.0492 in
Piston - Piston Ring Grove Width - Second
1.52-1.54 mm
0.0598-0.0606 in
Piston - Piston Ring Grove Width - Oil Control
2.52-2.54 mm
0.0992-0.1000 in
Piston - Piston To Bore Clearance
0.010-0.041 mm
0.0004-0.0016 in
Pin - Piston Pin Clearance to Connecting Rod Bore
0.007-0.026 mm
0.0003-0.0010 in
Pin - Piston Pin Clearance to Piston Pin Bore 0.002-0.012 mm
0.0001-0.0005 in
Pin - Piston Pin Diameter
19.995-20.000 mm
0.7872-0.7874 in
Pin - Piston Pin End Play
0.19-1.16 mm
0.0075-0.0461 in
Valve System
Valves - Valve Face Runout - Maximum
0.04 mm
0.0016 in
Valves - Valve Seat Runout - Maximum
0.05 mm
0.0020 in
Valves - Valve Stem Diameter - Intake
5.955-5.970 mm
0.2344-0.2355 in
Valves - Valve Stem Diameter - Exhaust
5.935-5.950 mm
0.2337-0.2343 in
Valves - Valve Stem to Guide Clearance - Intake
0.030-0.057 mm
0.0012-0.0022 in
Valves - Valve Stem to Guide Clearance - Exhaust
0.050-0.077 mm
0.0020-0.0026 in
Valve Lifters - Valve Lifter Diameter - Stationary Lash Adjuster
11.986-12.000 mm
0.0005-0.0020 in
Valve Lifters - Valve Lifter-to-Bore Clearance - Stationary Lash Adjuster
0.013-0.051 mm
3.2210-3.2299 in
Valve Springs - Valve Spring Load - Closed - @32.5 mm
245.0-271.0 N. - Eng Spec.
Valve Springs - Valve Spring Load - Open - @23 mm
525.0-575.0 N. - Eng Spec.
Displacement
2.0 L
122 CID
RPO
LSJ
Liter (VIN) P
Bore
85.992-86.008 mm
3.3855-3.3861 in
Compression Ratio
9.5:1
Bearing Clearance
0.030-0.063 mm
0.0012-0.0025 in
Bearing Diameter - Inside - Carrier
20.050-20.063 mm
0.7894-0.7899 in
Bearing Diameter - Outside - Carrier
41.975-41.995 mm
1.6526-1.6534 in
Bearing Journal Diameter
20.000-20.020 mm
0.7874-0.7882 in
Bushing Clearance
0.033-0.102 mm
0.0013-0.0040 in
Bushing Diameter - Inside
36.776-36.825 mm
1.4479-1.4498 in
Bushing Journal Diameter
36.723-36.743 mm
1.4458-1.4466 in
End Play
0.100-0.300 mm
0.0020-0.0118 in
Block
Balance Shaft Bearing Bore Diameter - Carrier
42.000-42.016 mm
1.6535-1.6542 in
Balance Shaft Bushing Bore Diameter
40.763-40.776 mm
1.6048-1.6054 in
Crankshaft Main Bearing Bore Diameter
64.068-64.082 mm
2.5224-2.5229 in
Cylinder Bore Diameter
85.992-86.008 mm
3.3855-3.3861 in
Cylinder Bore Out-of-Round - Maximum
0.010 mm
0.0004 in
Cylinder Bore Taper - Maximum
0.010 mm
0.0004 in
Cylinder Head Deck Surface Flatness - Transverse
0.030 mm
0.0012 in
Cylinder Head Deck Surface Flatness - Longitude
0.050 mm
0.002 in
Cylinder Head Deck Surface Flatness - Overall
0.08 mm
0.0031 in
Camshaft
Camshaft End Play
0.040-0.144 mm
0.0016-0.0057 in
Camshaft Journal Diameter
26.935-26.960 mm
1.0604-1.0614 in
Camshaft Thrust Surface
21.000-21.052 mm
0.8268-0.8252 in
Connecting Rod
Connecting Rod Bearing Clearance
0.029-0.069 mm
0.0011-0.0027 in
Connecting Rod Bore Diameter - Bearing End
52.118-52.134 mm
2.0519-2.05252 in
Connecting Rod Bore Diameter - Pin End
20.007-20.021 mm
0.7877-0.7882 in
Connecting Rod Side Clearance
0.070-0.370 mm
0.0028-0.0146 in
Connecting Rod Straightness - Bend - Maximum
0.021 mm
0.0083 in
Connecting Rod Straightness - Twist - Maximum
0.04 mm
0.0157 in
Lubrication System
Oil Pressure - Minimum - @1000 RPM
344.75-551.60 kPa
50-80 psi
Oil Capacity - with or without Filter
5.7L
6.0 quarts
Piston Rings
Piston Ring End Gap - First Compression Ring
0.20-0.40 mm
0.008-0.016 in
Piston Ring End Gap - Second Compression Ring
0.35-0.55 mm
0.014-0.022 in
Piston Ring End Gap - Oil Control Ring - Rails
0.25-0.76 mm
0.010-0.030 in
Piston Ring to Groove Clearance - First Compression Ring
0.04-0.08 mm
0.0015-0.0031 in
Piston Ring to Groove Clearance - Second Compression Ring
0.030-0.069 mm
0.0012-0.0027 in
Piston Ring to Groove Clearance - Oil Control Ring
0.090-0.106 mm
0.0035-0.0042 in
Piston Ring Thickness - First Compression Ring
1.170-1.190 mm
0.0461-0.0469 in
Piston Ring Thickness - Second Compression Ring
1.471-1.490 mm
0.0579-0.0587 in
Piston Ring Thickness - Oil Control Ring - Rail - Maximum
0.43 mm
0.0169 in
Piston Ring Thickness - Oil Control Ring - Spacer
1.574-1.651 mm
0.0620-0.0650 in
Pistons and Pins
Piston - Piston Diameter - @14.5 mm up
85.967-85.982 mm
3.3845-3.3851 in
Piston - Piston Pin Bore Diameter
20.002-20.007 mm
0.07875-0.7877 in
Piston - Piston Ring Grove Width - Top
1.23-1.25 mm
0.0484-0.0492 in
Piston - Piston Ring Grove Width - Second
1.52-1.54 mm
0.0598-0.0606 in
Piston - Piston Ring Grove Width - Oil Control
2.52-2.54 mm
0.0992-0.1000 in
Piston - Piston To Bore Clearance
0.010-0.041 mm
0.0004-0.0016 in
Pin - Piston Pin Clearance to Connecting Rod Bore
0.007-0.026 mm
0.0003-0.0010 in
Pin - Piston Pin Clearance to Piston Pin Bore 0.002-0.012 mm
0.0001-0.0005 in
Pin - Piston Pin Diameter
19.995-20.000 mm
0.7872-0.7874 in
Pin - Piston Pin End Play
0.19-1.16 mm
0.0075-0.0461 in
Valve System
Valves - Valve Face Runout - Maximum
0.04 mm
0.0016 in
Valves - Valve Seat Runout - Maximum
0.05 mm
0.0020 in
Valves - Valve Stem Diameter - Intake
5.955-5.970 mm
0.2344-0.2355 in
Valves - Valve Stem Diameter - Exhaust
5.935-5.950 mm
0.2337-0.2343 in
Valves - Valve Stem to Guide Clearance - Intake
0.030-0.057 mm
0.0012-0.0022 in
Valves - Valve Stem to Guide Clearance - Exhaust
0.050-0.077 mm
0.0020-0.0026 in
Valve Lifters - Valve Lifter Diameter - Stationary Lash Adjuster
11.986-12.000 mm
0.0005-0.0020 in
Valve Lifters - Valve Lifter-to-Bore Clearance - Stationary Lash Adjuster
0.013-0.051 mm
3.2210-3.2299 in
Valve Springs - Valve Spring Load - Closed - @32.5 mm
245.0-271.0 N. - Eng Spec.
Valve Springs - Valve Spring Load - Open - @23 mm
525.0-575.0 N. - Eng Spec.
1 - 20 of 39 Posts
Yeah I knew it was that high but I was surprised, the SRT-4 is only 8.5 or 8 to1 right??
Yes, that high comp ratio surprised the hell out of me when I first saw it.
9:5:1 compression means the motor wont be able to hold much w/ boost...
Hopefully some guys get that info before they start trying to push as much boost as possible and end up wearing the engine out quick.
SRT-4 is 8.1:1
SRT-4 is 8.1:1
You can always adjust the ratio when some decides to add more boost buy upgradeing the internals. But that will be expensive to do but i think would make the engine much safer to boost and tune. 
Yeah, that is kinda high. I would expect that out of the NA, but not the s/c. Doesn't Cometic make custom head gaskets? Maybe you could run a thicker gasket to give you a little more head room....but the hard part would be figuring out how to come up with the numbers for that.
That is really good info though for when time comes for a rebuild. It will happen, sooner or later.
That is really good info though for when time comes for a rebuild. It will happen, sooner or later.
WRicerX said:Yeah, that is kinda high. I would expect that out of the NA, but not the s/c. Doesn't Cometic make custom head gaskets? Maybe you could run a thicker gasket to give you a little more head room....but the hard part would be figuring out how to come up with the numbers for that.
That is really good info though for when time comes for a rebuild. It will happen, sooner or later.
Yeah expacailly when it goes you can alway rebuild it to take the boost.
Yep! Lower compression forged pistons for starters..then bring on the boost.
It's just a matter of time until tuners and the non financially challenged find out what this engine's limits are.
It's just a matter of time until tuners and the non financially challenged find out what this engine's limits are.
I think there are probably two reasons for the high static compression on the motor.
For one, when you drop compression to add boost, you lose some low-throttle performance (when you're not making boost). Not really a problem if you're talking about a 5.0L Mustang motor, but I bet this if this 2L motor were only run at 8.0:1, you'd have some drivability issues. It's slightly less of an issue on the SRT with the 2.4L (20% more displacement to make up for it).
The second is the M62 itself. It's a "smaller" unit, and as you lower static compression, the flow requirements of the S/C increase. Maybe too high for what the M62 is capable of (reliably) producing.
For one, when you drop compression to add boost, you lose some low-throttle performance (when you're not making boost). Not really a problem if you're talking about a 5.0L Mustang motor, but I bet this if this 2L motor were only run at 8.0:1, you'd have some drivability issues. It's slightly less of an issue on the SRT with the 2.4L (20% more displacement to make up for it).
The second is the M62 itself. It's a "smaller" unit, and as you lower static compression, the flow requirements of the S/C increase. Maybe too high for what the M62 is capable of (reliably) producing.
The stock WRX (2.0 ltr) has a CR of 8.0:1. When I was using the stock turbo, you could not feel any lag or driveability issue. But then again, the turbo was made for low end spool, but of course, top end suffered. It was not the biggest snail on the beach. So, it really comes down to the compatability to the equipment.
DanM said:I think there are probably two reasons for the high static compression on the motor.
For one, when you drop compression to add boost, you lose some low-throttle performance (when you're not making boost). Not really a problem if you're talking about a 5.0L Mustang motor, but I bet this if this 2L motor were only run at 8.0:1, you'd have some drivability issues. It's slightly less of an issue on the SRT with the 2.4L (20% more displacement to make up for it).
The second is the M62 itself. It's a "smaller" unit, and as you lower static compression, the flow requirements of the S/C increase. Maybe too high for what the M62 is capable of (reliably) producing.
You got some good points. Hummm.... Who knows really why.
how much boost do u think u can run with that high of a compression ratio? I was hopin to find a 18-20 lbs pulley, i mean everything else is solid i mean it has a metal head gasket, forged crank the list goes on
i just thought of something i pulled that info out of GM SI. What if its 9:1 after boost is added?
Spoke to Chris White online tonight. Hes in research and development for the high perforamcne engines center. He said that the cars break at 14 lbs of boost. Pistons and Rods being the biggest contributors.
Ouch, that's not much room to play with. What PSI do they run, stock?
the 2.2L ecotec is a 10.0:1.
I'm going to try to find what these thigns run for stock boost, but hopefully someone with one will gives us an accurate number.
Just doing a google search I am still finding conflicting numbers.
Mostly I see 10-12lbs. but I have also seen anywhere from 8-10lbs also, I am thinking it's closer to the 10-12.
I'm going to try to find what these thigns run for stock boost, but hopefully someone with one will gives us an accurate number.
Just doing a google search I am still finding conflicting numbers.
Mostly I see 10-12lbs. but I have also seen anywhere from 8-10lbs also, I am thinking it's closer to the 10-12.
Here we go again ... boost does NOT equal power. In fact, there's not even any sort of linear relationship between the two WHATSOEVER. You can have a motor making 10psi producing more power than a very similar one making 15psi. It makes absolutely zero sense to say that a motor will 'break' at a certain boost pressure. FYI, people have had the Ecotecs at much more than 14psi (via either turbo or SC) without any problems.wheelburns said:Spoke to Chris White online tonight. Hes in research and development for the high perforamcne engines center. He said that the cars break at 14 lbs of boost. Pistons and Rods being the biggest contributors.
The LSJ makes about 12lbs max in stock form.
So you're saying if I take 2 identical SRT-4's.....leave one stock and put one at 40psi. They will last the same amount of time.DanM said:Here we go again ... boost does NOT equal power. In fact, there's not even any sort of linear relationship between the two WHATSOEVER. You can have a motor making 10psi producing more power than a very similar one making 15psi. It makes absolutely zero sense to say that a motor will 'break' at a certain boost pressure. FYI, people have had the Ecotecs at much more than 14psi (via either turbo or SC) without any problems.
The LSJ makes about 12lbs max in stock form.
Not taking a 10psi engine and a "similar" 15psi one, taking the exact same engines and testing them against each other, the exact same engine and components a 10psi version isnt going to have more power than the 15.
Yeah I am sure you can take one engine, port and polish everything, balance and blueprint everything, add water/alky injection, map clamp, injectors, different intakes and exhaust, other components the 10psi may have more power, but the exact same engine/car setup.....how will the 15psi car make less power.
Boost leaks don't count.
and boost does not equal power? so how are people going from stock boost turning it up to 19psi and they are getting quicker times or showing more hp on the dyno? are they cutting down wind resistance?
1 - 20 of 39 Posts
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