Compression Test. What does Honda Specify ?

[86-accord-lxi]

Hey everyone,
I did a compression test on my 86 lxi for the hell of it,
I got 130 psi on cylinders 1, 2, and 3, cylinder 4 was 150 psi.
My question is what does honda specify the compression to be ?
If anyone can tell me It would be most appreciated.

[88Accord-DX]

I'm not sure what Honda specifies as the lowest compression readings to have. I've seen some people talk about 142 p.s.i. was the lowest you want to be at. 150 p.s.i. isn't too bad. Not sure how long that p.s.i. would last though.

Around 175- 180 p.s.i. is OEM compression readings on a new factory engine.

[hyongel]

The 1988 service manual says 178 psi nominal/135 psi minimum for injected engines, with a max variation of 28 psi between cylinders.

[Soundy]

It's rare that ALL cylinders will lose significant compression... old-timer wisdom is that the cylinders should all be within, IIRC, 20% of each other. The exact number isn't as critical as long as they're all close to the same.

[86-accord-lxi]

I always thought it was 10%, Is it 20%, or 10% ?

[Soundy]

I'd say 20% is probably okay, but of course, 10% is better :)

[newaccorddriver]

The 1988 service manual says 178 psi nominal/135 psi minimum for injected engines, with a max variation of 28 psi between cylinders.


i hate to resserect old threads, but i did a compression test today and my results were 130, 125, 125 and 130.

i think 178psi is pretty high for an A20 series motor considering my friends H22 motor is putting about 180psi or so on a fairly new motor and his was actually a high compression motor.

[88Accord-DX]

i did a compression test today and my results were 130, 125, 125 and 130.
That is below the lowest reading you want to be at. Leak down test will see if the rings are shot. Your motor is tired. Hope you make it through your rebuild if you plan on doing it. Takes some money to do it right.


i think 178psi is pretty high for an A20 series motor considering my friends H22 motor is putting about 180psi or so on a fairly new motor and his was actually a high compression motor.
A20 series motors are considered high compression motors as far as I know with the valve releifs in the tops of the pistons. They have 178 psi at nominal pressure.

[newaccorddriver]

That is below the lowest reading you want to be at. Leak down test will see if the rings are shot. Your motor is tired. Hope you make it through your rebuild if you plan on doing it. Takes some money to do it right.

hopefully ill be doing a rebuild rather then retiring the car. its very tired for its age, and the problems that are surfacing are just making it worse. i guess the hardest thing isnt getting the money for a rebuild(even though im unemployed), or even the time(ive got plenty of time at this moment), i think its really finding the right block to rebuild. id hate to pick up a block thats got a hairline crack in it cause i really dont know where to get certain stuff done(like magnafluxing). ive already posted a WTB ad in a local forum that im with trying to get another A20 motor i can rebuild, but the 2 guys that messaged me are wondering why i wont take a prelude one. thats also another thing with buying from someone you dont really know, you dont know if their lying or not cause the guys that messaged me have new accounts. if they got something i dont want, then theyll message me from a new account and BS me into thinking its an accord block.

for some odd reason i cant message elijah, but i know hes got a spare motor at his place. not sure if hes willing to sell it though...


A20 series motors are considered high compression motors as far as I know with the valve releifs in the tops of the pistons. They have 178 psi at nominal pressure.


what are valve reliefs?

[88Accord-DX]

Valve releifs are indentions in the tops of the pistons to make it simple. As far as Prelude motors, the 86-89 Accord has a lot of engines that can be swapped into the Accord that the Prelude has. The B series motor in the Prelude can be swapped into the Accord.

I'm not into swapping motors on this car. just fixing them.

[3gn86lxi]

I had 160 across all cylanders a while ago. And thats with almost 250000 miles.

[newaccorddriver]

The B series motor in the Prelude can be swapped into the Accord.


are you serious? i thought only an accord B20 would work. and i thought the USDM B20A3(or whatever number it was) and the JDM accord B20 had very little in common

[88Accord-DX]

Don't quote me. I just know the manuals on the Accords cover the Prelude motors as far as Haynes & Chiltons. I'm not into the "swapping motor thing". So I could be wrong. I do know that some B series motors can be swapped. What it comes out of, I'm not sure. Just know it is B series.

[newaccorddriver]

Don't quote me. I just know the manuals on the Accords cover the Prelude motors as far as Haynes & Chiltons. I'm not into the "swapping motor thing". So I could be wrong. I do know that some B series motors can be swapped. What it comes out of, I'm not sure. Just know it is B series.


thought so cause the prelude motors are tilted towards the firewall while the accords are tilted towards the radiator

[Soundy]

That could be just a matter of different position of the motor mounts in the engine bay...

[newaccorddriver]

That could be just a matter of different position of the motor mounts in the engine bay...


if thats the case, then i think the rear and front mounts wont mount properly due to the tilt of the motors

[87preludeA20A3]

well the earlier b20 engines in early 88-89 preludes sat straight in the engine bay... go look in a junk yard and you will see...

[Blkblurr]

I have a question about psi measured on our A20 engines. If the compression ratio is 10.1 to 1 and atmospheric pressure is about 14.7 psi, Houw can the compression be any better than about 148 on a stock engine? 14.7 X 10.1

[hyongel]

I would guess when you compress air in the cylinder, the air temperature goes up a bit due to the work being done on it. That would raise the pressure above what you would expect from the volume ratios. P=nRT/V for an ideal gas ...

[shepherd79]

when i rebuild the engine, my compression was 180 psi. on all 4 cylinders.
Stock A20 motor should be anywhere between 175-180 psi on stock or rebuild engine.

[newaccorddriver]

when i rebuild the engine, my compression was 180 psi. on all 4 cylinders.
Stock A20 motor should be anywhere between 175-180 psi on stock or rebuild engine.

180... i guess that means my rings are really shot up.


on a more general question, when it comes to rebuilding a motor, can i use an A20A1 block instead of an A20A3 block? does it really make a different what one i use?(mines a BT block)

[Blkblurr]

I would guess when you compress air in the cylinder, the air temperature goes up a bit due to the work being done on it. That would raise the pressure above what you would expect from the volume ratios. P=nRT/V for an ideal gas ...

That makes sense. That would raise the pressure quite a bit.

[FyreDaug]

I would guess when you compress air in the cylinder, the air temperature goes up a bit due to the work being done on it. That would raise the pressure above what you would expect from the volume ratios. P=nRT/V for an ideal gas ...

Best newbie post of 2006 award!

[FyreDaug]

180... i guess that means my rings are really shot up.
on a more general question, when it comes to rebuilding a motor, can i use an A20A1 block instead of an A20A3 block? does it really make a different what one i use?(mines a BT block)

Oh, and yes, any A20 series block will work fine