Compression test reading from 250-270 on F22
05-23-2011, 04:44 PM
#1
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Compression test reading from 250-270 on F22
So i bought a compression gauge and followed the DIY to get Compression numbers and they seemed off to me.
Heres the numbers in order.
Here are my numbers from the front to back of the block.
Isnt this too high?
268
269
280
268
Im going to replace my compression gauge tomorrow hopefully its busted.
The reason these qeustions arise is because i had my 2004 ap2 tuned with AEM and only hit a 207 on a mustang dyno, which didnt bother me much but than an ap1 with the same mods as me (intake/exhaust/test pipe) making 214
while i had a no name header (its not cracking) intake exhaust test pipe AND crank pulley so i should have slightly higher numbers yet i only made 207... but the ap1 made 214 horse power on the dyno.
Heres my dyno. Torque is only at 120 as well...my torque as an ap2 should be higher than my friends.
Heres the numbers in order.
Here are my numbers from the front to back of the block.
Isnt this too high?
268
269
280
268
Im going to replace my compression gauge tomorrow hopefully its busted.
The reason these qeustions arise is because i had my 2004 ap2 tuned with AEM and only hit a 207 on a mustang dyno, which didnt bother me much but than an ap1 with the same mods as me (intake/exhaust/test pipe) making 214
while i had a no name header (its not cracking) intake exhaust test pipe AND crank pulley so i should have slightly higher numbers yet i only made 207... but the ap1 made 214 horse power on the dyno.
Heres my dyno. Torque is only at 120 as well...my torque as an ap2 should be higher than my friends.
05-23-2011, 06:16 PM
#2
I don't see much wrong with your compression numbers they are reasonable IMO. Not much wrong with your dyno numbers either, pretty good for a Mustang Dyno. Comparing dyno numbers isn't all that accurate, perhaps the Ap1 was just running exceptionally strong and the parts it has are working perfectly for that setup. I wouldn't sweat the details as long as your car is running well which it seems to be doing by the compression and dyno numbers.
05-23-2011, 06:29 PM
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True because the car does run fine but look at the torque on our dynos, his even gets higher than mine, and as an ap2 verse ap1 that should not have happened. Plus i think these compression numbers are ludicrous
05-23-2011, 08:38 PM
#4
Did you guys run on the same dyno on the same day in the same weather conditions conditions ? , if so maybe your no-name header is the problem, it's not uncommon for an aftermarket header to make less power and torque than the oem header. If your parts and tune are worse than the other guys it is possible to make less power and torque regardless of the engine differences. If you didnt dyno together on the same day and in the same weather conditions you cant make a very accurate comparison.
Your engine is making more bottom end torque than the other engine , which is about right considering the rated numbers for the two different engines. So you are making more bottom end torque due to the additional displacement of the ap2, so that is fine. But the ap1 is making really good top end torque after the vtec crossover point due to its tuning or aftermarket parts, where your eninge is running flat on its face on the top end. The difference on the top end is all about tune and the aftermarket parts being used, the other car simply has a better tune and/or parts on it and has a stronger top end. What are the different intakes being used, what are the different exhausts being used , and who knows what the no name header is doing to your engine. I can`t tell what your header is doing to your top end but I will tell you that I`d never run a cheap no name header on this engine as it`s likely to be worse than the oem part. Something is affecting your top end power, bad air-fuel ratio, worn sparkplugs, bad aftermarket parts or any combination of the three.
I still don't see anything wrong with your compression numbers, they look great, don't get caught up in the outright numbers the main thing is that they are even between cylinders and within spec from cylinder to cylinder, below the maximum variation spec.
Your engine is making more bottom end torque than the other engine , which is about right considering the rated numbers for the two different engines. So you are making more bottom end torque due to the additional displacement of the ap2, so that is fine. But the ap1 is making really good top end torque after the vtec crossover point due to its tuning or aftermarket parts, where your eninge is running flat on its face on the top end. The difference on the top end is all about tune and the aftermarket parts being used, the other car simply has a better tune and/or parts on it and has a stronger top end. What are the different intakes being used, what are the different exhausts being used , and who knows what the no name header is doing to your engine. I can`t tell what your header is doing to your top end but I will tell you that I`d never run a cheap no name header on this engine as it`s likely to be worse than the oem part. Something is affecting your top end power, bad air-fuel ratio, worn sparkplugs, bad aftermarket parts or any combination of the three.
I still don't see anything wrong with your compression numbers, they look great, don't get caught up in the outright numbers the main thing is that they are even between cylinders and within spec from cylinder to cylinder, below the maximum variation spec.
05-23-2011, 09:11 PM
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Those numbers do look high to me. My quick google search says new factory spec is 228, but many people report up to 240. My guess is your tester is faulty and your engine is running just fine. It is possible though, that your engine has some carbon build up increasing compression. This may result in knock and retarded timing.
05-23-2011, 10:08 PM
#6
the tester is reading high, but it's consistent between the 4 cylinders so I wouldn't worry about it being on the high side, a lot of aftermarket testers read inaccurately in terms of outright numbers, the main thing is if they are consistent on all cylinders.
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05-24-2011, 07:54 AM
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Does it make sense that my max torque is lower than an Ap1?
And that im losing up to 10 horse power with the header? I'll get it swapped out a.s.a.p. but in my opinion i should have been making MORE power than Presto, as i have an f22 and al the same mods plus the crank pulley, which is debatable to how much power but it should have given me at least 2 or 3
And that im losing up to 10 horse power with the header? I'll get it swapped out a.s.a.p. but in my opinion i should have been making MORE power than Presto, as i have an f22 and al the same mods plus the crank pulley, which is debatable to how much power but it should have given me at least 2 or 3