BillyMoritz

First, I am no mechanic. I do understand what a CT shows and why people ask for them. I'm selling my car and people ask for CT numbers, so I took my car to the Honda dealership for a test.

I get results of 185/180/185/185. I come look here and I see people saying they get 240. So I call the Honda place to ask, what's the deal.

I talk to the service guys, and I am told there was no way it should have been 240 and that on their tests that it should never get as high as 200 when brand new. For some sense of comparison, I asked them what number is low enough to be a problem. I was told 128. That's pretty specific, which makes me feel like they were not just guessing. It's a successful dealership, I bought my first S2000 in 2002 when its was a new 2002 model. The parts manager has an S2000. They are pretty sharp.

What's the deal with the 240s

jr94513

I have a 00 ap1 with 45,xxx miles and my compression is at 240 all the way across. Perhaps they did yours with the engine cold that's why the numbers are a bit low. Most s2ks that have solid engines are around 210+ range. 185 is a bit low but at least its consistent. Be concerned when there is a 20psi+ difference between the cylinders. Might want to get a second opinion.

eight

Different compression testers give different readings. You don't really need to be looking at specific numbers just large gaps between cylinders. I.E. 220/220/180/210. That might indicate a problem in cylinder 3.

With that being said, having all cylinders being too low can be a problem as well.

Regardless, judging by your numbers, you have a healthy motor.

franky

Seem like it was done cold or they didn't open the throttle. Either way, if there's no big difference between the cyls, I say its a healthy engine.

BillyMoritz

It must have been the amount of throttle they run. It was tested at a Honda dealership and they told me they'd never test a cylinder to even 200.

It's not that it wouldn't test high, they were emphatic, they should never be above 200. Oh well...I don't totally understand what the numbers mean, I do get the reason you wouldn't want the numbers to vary. I guess I just tend to take the dealership as gospel. Why shouldn't I?

Car Analogy

Here is the deal. Most cars dont have such a high compression ratio the S has. So for most eveey car, import, domestic, 185 is a sort of Gold Standard. So to most car guys, if you meet that, your engine is perfect. Even performance cars this is still the number to shoot for.

Mention 195 psi CR to the average car guy or mechanic, and their eyes will get big. Wow! Huge numbers. 200 is like a pipe dream. You'd get laughed at.

So our typical 240 is well beyond the realm of possibility to most people that work on cars. Its a stupidly outrageous number.

But our cars have motorcycle like compression ratios. Just another way our cars are dissimilar to most anything else. So 240 is normal perfect. Kinda equivalent to 185 for 'regular' cars.

So here is what happened. They took your car, wrote down some numbers that they thought would sound really good, yet believable, charged you money, and never even opened the hood. They ripped you off. Not at all surprising, really.

Most independent shops aren't much better with CR testing. They think the only reason anyone would ask for this test is if they suspect something major wrong with their engine. So most shops will not even test it, and give you bad numbers, to confirm your fears.

They do this to try and get unneeded work from you, but also to protect themselves. If they say it checks out, then tomorrow your motor is blowing smoke, they dont want to get sued.

So, moral of story is you want CR test done right, ypu gotta do ot yourself...

Sent from my SM-G920P using IB AutoGroup

snitm

I got better compression numbers on my 2002 AP1 once I upgraded my battery (after test1, before test2).

compression test1: (6/3/2015)
cylinder 1: 225, 221, 225
cylinder 2: 226, 227, 225
cylinder 3: 215, 224, 221, 223, 221
cylinder 4: 231, 217, 220, 218

Cylinder 3 freaked me out initially but averaged out all looks fine to these untrained eyes.

compression test2: (10/28/2015)
cylinder 1: 227, 225, 240
cylinder 2: 220, 227, 235
cylinder 3: 230, 233
cylinder 4: 235, 235