Alfa Romeo Giulia Forum banner
1 - 20 of 56 Posts

·
Registered
Joined
·
702 Posts
Discussion Starter · #1 ·
So I just had the car in for service. Serpentine belt, spark plugs, cabin filter, oil change and requested a compression test. Total $2500

Surprisingly, cylinder 3 is fine. Cylinders 3, 4, 5, and 6 were all 118-122.

Cylinders 1 and 2 were both 100.

Funny thing is car had CEL and throttle control light lit up as I picked it up from the dealer.

Opinions?

Should I have another mechanic do the test to see if the results are the same? Dyno the car to see what power it’s making?

The tech said it’ll probably be an issue down the road and they’ve replaced 7-8 QV motors, half of them tuned. Said they could try warranty if I were to return everything to stock but can’t promise. I don’t really like lying and want to do all that anyway.

Leaning toward taking off the aftermarket stereo and wheels and trading it in while used car values are super high. 2018 with 30k miles. Was going to keep it until ~50k miles.
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,457 Posts
Have second test. Maybe oil analysis too.

Based on results you can do a CarMax dump lol
 

·
Registered
Joined
·
414 Posts
I wouldn't put too much faith in compression tests on these motors, especially when the low numbered cylinders are on the deactivation side. Dyno numbers would definitely be better. I'd also recommend a leak-down test on those cylinders... can be difficult to do though since the crank is hard to turn, to get it lined up to TDC( on the cylinder to be tested). Better yet, see if someone can scope the motor and do a cylinder power balance test.
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,457 Posts
Disconnect and reconnect negative terminal right before making a pull?
Exactly. You'll see the Christmas tree of lights showing your abs tc ecs forward collision etc is disabled
 

·
Registered
Joined
·
702 Posts
Discussion Starter · #8 ·
Thanks. That’ll probably be my next step. It should make close to 500whp with the mods.

Might do some 60-130 pulls. Supposed to be under 60 degrees Thursday morning. Ran 7.7-8.1 before.

If the dyno and 60-130 are fine, maybe keep it for now.
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,457 Posts
Btw i don't recommend a dyno at all. There is no way to predict your crank power from whp numbers. Ive seen the exact same model mustang dyno reading 10 percent different from each other at different facilities. Seen dyno dynamics showing somewhere around 40 percent drivetrain loss. not joking. Seen dynapaks spit out higher whp numbers than the car is rated for at the crank. Seen big drum dynojets read 10 percent lower than the local mustang.


Whether the car makes 400whp or 500whp on the dyno you really won't be able to glean anything from it.
 

·
Registered
Joined
·
2,405 Posts
Because you asked "Options?", this is mine:

I am sure you already know it. Simply, ignore those BS CELs which do not mean anything. I am sure you have noticed zero power lost, zero compression issues and that car is still performing like a beast. Clear the the OBD2 error codes and continue enjoying your Dream Car. If you keep it, you (and me and many others) will be posting the same stuff about CELs for the next 100,000 miles. It has been demonstrated, and once again, you just demonstrated, that it si nothing. It is for sure an annoying CEL showing up sometimes, which normally clears with the 4 start/stops SOP and the error codes is erased with the tool, with zero consequences. Enjoy it.
 

·
Registered
Joined
·
4,168 Posts
60-130 pulls will be you’re best bet to see if power is low. Anything from 7.8-8.3 should be normal power on same stretch of road in same DA and temps. If you run a high 8s low 9s you know something is up. If you don’t dyno on same dyno as before you basically will get more info and confusion than before. 500 whp should be good enough to get high 7s 60-130.
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,457 Posts
60-130 pulls will be you’re best bet to see if power is low. Anything from 7.8-8.3 should be normal power on same stretch of road in same DA and temps. If you run a high 8s low 9s you know something is up. If you don’t dyno on same dyno as before you basically will get more info and confusion than before. 500 whp should be good enough to get high 7s 60-130.
Good call.

That and better yet datalogging. You can log air imtake volume and requested and actual torque
 

·
Registered
Joined
·
2,405 Posts
Talking about the thread title, I think that "... healthy engines should have compression at/over 100 psi per cylinder ... So, I would suggest to re-write the threat title and eliminate what is within parenthesis leaving only the compression test results part. I think that people will assume that you are asking for options. I did not know that you were going to judge the options, too.
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,457 Posts
Talking about the thread title, I think that "... healthy engines should have compression at/over 100 psi per cylinder ... So, I would suggest to re-write the threat title and eliminate what is within parenthesis leaving only the compression test results part. I think that people will assume that you are asking for options. I did not know that you were going to judge the options, too.
Thats not necessarily correct. Compression test results are relative to each other. If you have 4 cylinders at 125psi and two at 105 youd want to dig deeper. If you had 6 at 110 psi on the same car id likely not bat an eye. His results would at least make me want to investigate more.
 

·
Registered
Joined
·
702 Posts
Discussion Starter · #16 ·
Does anyone build these motors btw?

Ive blown up some motors in my day but you can get out the door under $10k for a domestic or Japanese short block with forged pistons and rods. I would think it shouldn’t be any more complicated for an Alfa other than finding someone to work on it.

Sure as hell ain’t paying the dealer for a complete new long block.
 

·
Registered
Joined
·
702 Posts
Discussion Starter · #17 ·
Talking about the thread title, I think that "... healthy engines should have compression at/over 100 psi per cylinder ... So, I would suggest to re-write the threat title and eliminate what is within parenthesis leaving only the compression test results part. I think that people will assume that you are asking for options. I did not know that you were going to judge the options, too.
The cylinders should be within 10% of each other.
 

·
Registered
Joined
·
414 Posts
The cylinders should be within 10% of each other.
They should, but as you lose oil pressure in the deactivation system, build heat in cylinder walls, lose oil coating on the cylinder walls and lose cranking voltage, this can all cause a loss by the time you get through all of the cylinders. If I was to guess, 1 and 2 may have been the last, or first, tested. See if the dealership has a Pico scope(they shipped them to all Mopar dealers) and have them do a power balance test, it'll show differences in cylinder speeds so you can identify if one or two really have low compression.
 

·
Registered
Joined
·
2,405 Posts
As a rule of thumb and in general terms, compression at/over 100PSI per cylinder and 10% variation between each other is perfectly OK. I do not see an extraordinary and terrible issue with a 18% and a 22% variation. This is not a perfect science but, an estimate. In any case, it's your engine so, you can please proceed as you think appropriate. That was my option, not good or bad, just an option.
 
1 - 20 of 56 Posts
Top