Skyline Detonating On Dyno

[GotsWapan]

I can't answer half these questions, as I don't know enough about it. I never saw it blow any blue smoke with the old turbo but a friend claimed he saw a little bit a while ago.

It might be an aftermarket intake pipe as its not running an AFM, I'm not sure.

The car ran fine before I went to do this stage of upgrades.

[skylinecouple]

So you add 0.2-0.6mm for every 0.005" they take off the head?

Your assuming they actually took .005 off. Personal experience and the experience of way too many people on these forums is, you have one guy doing the machining, one guy building the engine and yet another tuning. Who shaved too much off ? Who tuned it wrong ? Who put the engine together wrong ? No one ownes up to mistakes and yet again the poor old owner bares the brunt of school drop outs who casually wander through tech and get a peice of paper saying they are now a qualified mechanics. Apologies to those mechanics who actually give a sh#t.

I guess the best way to take the car to the next level is to get one shop to do everything, let them try to blame someone else then. And no, I am not saying this shop is blaming someone else, I am being general in my comments. But I am sure this particular case will turn out just fine.

[WMDC35]

I agree with it being hard to find good mechanics, that's why you do it yourself, also hard to fix problems when you're not sure what you're starting with

[GotsWapan]

So it turns out it was excessive oil in the intercooler that was lowering the octane rating of the fuel.

[AngryRB]

really? does it have that much effect, so a oil separater really is a good idea for high power cars, i thought that would just add to lubrication in the cylinders

so any more results? dyno print out?

and +1 about finding decent mechanics/tuners, PM me if you wanna know who to avoid in brissy..

Edited May 22, 2012 by SliverS2

[GotsWapan]

I will have a dyno print out on or by the weekend. Tuners said the rear muffler has somehow collapsed in the middle so that's going to restrict the power a little.

I don't know a big deal about it ,but yes, I'd say its a pretty plausible theory , Mark

[Moodles2]

Oil had to come from somewhere, turbo (oil seals), or excessive blowby ("rebuilt" bottom end built by a monkey, rings that didn't seal properly etc.) or the intercooler has been full of oil the whole time and wasn't cleaned out when whatever was the cause before the engine needed the rebuild.

[GotsWapan]

The bottom end and head are only about 6000kms old. Ive been told motors can have decent blow by till around 10,000kms?

[GotsWapan]

As well as unknown condition of the old turbo, yes

[51NNA]

The bottom end and head are only about 6000kms old. Ive been told motors can have decent blow by till around 10,000kms?

Back in the day yes, not these days unless the builder gapped the rings wrong.

[GotsWapan]

Well it never really used oil, constantly checked the dipstick, yet to find out the condition of the turbo

[R31Nismoid]

The bottom end and head are only about 6000kms old. Ive been told motors can have decent blow by till around 10,000kms?

Absolute rubbish. Within the first 20mins, it should be run/bed in and ready to tune up.

Excessive blow-by after that means it's a rubbish build

[HYPED6]

really? does it have that much effect, so a oil separater really is a good idea for high power cars, i thought that would just add to lubrication in the cylinders

Oil, and carbon deposits can make that much difference.

I have seen as much as 14 deg timing being able to be added after removing all contaminates from cooler piping/cooler and cleaning carbon off the tops of pistons.

Detonation is not as easy as "o Its pinging..... I will just get out my crystal ball and see what the cause is..... "

Possible causes........

Tune related.......

Too much ignition timing (AFR Dependent)

Not enough ignition timing (only seen this maybe once)

Too much fuel (same again... maybe twice)

Not enough fuel (but is also in relation to timing as well)

Mechanical Engine related.....

Too much compression

Anything protruding into the combustion chamber that shouldn't be there

Exhaust back pressure from exhaust, turbine housing, turbine.

Damaged compressor wheel

And well, we can call this "other" I guess

Too much heat in the combustion chamber

Timing jitter. If you don't know what this is yet then get reading.

Contaminants in the intake, oil etc

Incorrect fuel used for the application

Intercooler, causing to much pressure drop..... or not cooling properly.

and honestly....... the absolute biggest cause of detonation is customers expectations.

"But I read on the internet that my 30/76 on a RB25 should make 430rwhp on 98 octane because I have a built engine and have spent all this money and now its your fault because its not making the power"

This is what makes engines detonate. Now how long does it take to test for all these things especially when you have allocated 5 hours for a tune..... and not 2 days from removal and refit of parts when you have other customers booked in as well.

Honestly you should be happy that they actually have the correct equipment and actually heard the detonation. Knowing this, when it is fixed your engine will live a long and happy life.

I bet you would be more upset if they didn't hear it and it made awesome power and your engine went bang in 3 days..... how good would that be.

Edited May 22, 2012 by HYPED6

[HYPED6]

You need to get your car outta that shop ASAP before they knock the bearings out of it (if it hasnt already) or worse... detonating in the top end = big trouble!! Its also the hardest to hear/detect so if they're certain thats whats happening i would be really concerned if i was you... To say they dont know why its detonating is reason enough for any person to question there ability. You need to ask questions like How timing have they put in at the point of det? What are the lambda readings at that point? If those questions arnt answered quickly and confidently then its obvious they dont know what they're doing.

You should read my above post. Im sure with the information provided you will be able to give me a clear and precise diagnosis of the mentioned pinging. Shouldn't you? I mean it can only be maybe one of about 15 things

[The Dan]

Your assuming they actually took .005 off. Personal experience and the experience of way too many people on these forums is, you have one guy doing the machining, one guy building the engine and yet another tuning. Who shaved too much off ? Who tuned it wrong ? Who put the engine together wrong ? No one ownes up to mistakes and yet again the poor old owner bares the brunt of school drop outs who casually wander through tech and get a peice of paper saying they are now a qualified mechanics. Apologies to those mechanics who actually give a sh#t. I guess the best way to take the car to the next level is to get one shop to do everything, let them try to blame someone else then. And no, I am not saying this shop is blaming someone else, I am being general in my comments. But I am sure this particular case will turn out just fine.

Yes, when a cylinder head is presented to a competent engineer for rebuild or refresh they generally take off 0.005" or 0.008" when they have slight warp.

More than 0.010" is severe. My point is, just because the head was shaved, doesn't mean everyone needs to run out and add 0.5mm (0.020") in thickness to their head gasket.

My personal experience is that it's stupid to rely on one person to do it all.

1. Chilton Engineering do all my engineering work - no I DO NOT rely on them to measure bearings or get clearances right, I blueprint all my engines personally.

2. Even though I am quite capable of honing a bore etc, why would I do that myself when there is someone like Chilton to do it for me who does it every day and have done for the last 50 years - yes they have been around for that long. They have the million dollar equipment to do the job to a level of perfection that I cannot achieve.

3. I do not tune cars. Sean from EFI Performance tune cars. Sean is probably one of the best tuners in this country and it has taken me several years to find him. I can tune cars. How stupid would it be for me to start tuning cars when Sean (used to be) tuning one street away? I'd waste days and weeks of time competing with another business that specialises in doing that one thing

4. I am so confident in the quality of my engineer and my tuner that I can actually give warranty on a 700hp engine....and do.

It's not a good idea for a customer to go to several different places to get work done but it is even worse to expect a workshop to do everything.....and to expect the highest quality from every part of the job. Do one thing to perfection and allow others to do other things to perfection. It's teamwork IMO.

@ WMDC35 - yes it can be frustrating having problems with workshops. It's even worse, though, when we get cars dropped off and they are an absolute mess because they weren't aware of how to do the job properly. It's more than nuts and bolts with these things. Doing odd jobs yourself is great if you wanna learn, but expect to pay more when it needs to be fixed.

[GotsWapan]

Absolute rubbish. Within the first 20mins, it should be run/bed in and ready to tune up.

Excessive blow-by after that means it's a rubbish build

Christ, go easy I'm only an amatuer I know f**k all about this stuff.

[NoFigJamHere]

Oil, and carbon deposits can make that much difference. I have seen as much as 14 deg timing being able to be added after removing all contaminates from cooler piping/cooler and cleaning carbon off the tops of pistons. Detonation is not as easy as "o Its pinging..... I will just get out my crystal ball and see what the cause is..... " Possible causes........ Tune related....... Too much ignition timing (AFR Dependent) Not enough ignition timing (only seen this maybe once) Too much fuel (same again... maybe twice) Not enough fuel (but is also in relation to timing as well) Mechanical Engine related..... Too much compression Anything protruding into the combustion chamber that shouldn't be there Exhaust back pressure from exhaust, turbine housing, turbine. Damaged compressor wheel And well, we can call this "other" I guess Too much heat in the combustion chamber Timing jitter. If you don't know what this is yet then get reading. Contaminants in the intake, oil etc Incorrect fuel used for the application Intercooler, causing to much pressure drop..... or not cooling properly. and honestly....... the absolute biggest cause of detonation is customers expectations. "But I read on the internet that my 30/76 on a RB25 should make 430rwhp on 98 octane because I have a built engine and have spent all this money and now its your fault because its not making the power" This is what makes engines detonate. Now how long does it take to test for all these things especially when you have allocated 5 hours for a tune..... and not 2 days from removal and refit of parts when you have other customers booked in as well. Honestly you should be happy that they actually have the correct equipment and actually heard the detonation. Knowing this, when it is fixed your engine will live a long and happy life. I bet you would be more upset if they didn't hear it and it made awesome power and your engine went bang in 3 days..... how good would that be.

How on earth can you blame a customer if the engine is damaged by detonation? This is 100% ENTIRELY the tuners fault!!! Because the customer has paid the "tuner" so it doesn't detonate... Your saying that the customers expectations is the "Absolute biggest cause of detonation" is ludicrous!! Surely a tuner would just explain to a customer that what ever power it makes is the best he can get out of it!! The issue your refering to is when a workshop/tuner makes claims that once he modify's/tunes/builds the car it WILL make xxx power and then to try and back up the "promises" only to kill the engine!! And who takes 5 hours to re-tune a new turbo/injectors???

Oh n BTW if i had the OPs car on a dyno and couldn't figure out why its detonating i would b looking for another career the next day..... And i dont beleive the explaination the shop gave him is a truthful one...The car never had this issue before he dropped it into the shop..

[51NNA]

L O L I liked the part about "Honestly you should be happy that they actually have the correct equipment and actually heard the detonation."

and "especially when you have allocated 5 hours for a tune..... and not 2 days"

Who could possibly take 2 days to tune a car? Imagine the bill, hi yes that will be 1600$ please oh and great news it made 6kw more!

Edited May 23, 2012 by 51NNA

[HYPED6]

How on earth can you blame a customer if the engine is damaged by detonation? This is 100% ENTIRELY the tuners fault!!! Because the customer has paid the "tuner" so it doesn't detonate... Your saying that the customers expectations is the "Absolute biggest cause of detonation" is ludicrous!! Surely a tuner would just explain to a customer that what ever power it makes is the best he can get out of it!! The issue your refering to is when a workshop/tuner makes claims that once he modify's/tunes/builds the car it WILL make xxx power and then to try and back up the "promises" only to kill the engine!! And who takes 5 hours to re-tune a new turbo/injectors???

Oh n BTW if i had the OPs car on a dyno and couldn't figure out why its detonating i would b looking for another career the next day..... And i dont beleive the explaination the shop gave him is a truthful one...The car never had this issue before he dropped it into the shop..

Did they damage the engine? or did they diagnose the detonation was there?

Also can you please confirm how you know there was absolutely no detonation before it went to the shop?

Im glad that your expectations of your self are so high that you would be able to fix the car the same day. I wish I was that confident in life.

Well, I am actually....... and as soon as I am, another car comes along and shows me that I know bugger all and to pull my head back in and keep learning.

I hope you have a great day diagnosing cars today. Its your gift from god. Stop hiding it from everyone

[HYPED6]

L O L I liked the part about "Honestly you should be happy that they actually have the correct equipment and actually heard the detonation."

and "especially when you have allocated 5 hours for a tune..... and not 2 days"

Who could possibly take 2 days to tune a car? Imagine the bill, hi yes that will be 1600$ please oh and great news it made 6kw more!

You would be surprised.... Yes spending 2 days on the dyno is not how i intended that.

However, Car comes in.... makes ghey power.... spend 4 hours working out why.....needs new valve spring.... springs go in... car goes back on the dyno..... car gets re tuned...

How long do you think this process takes? Buy the time you order the springs, get them, spend 5 hours changing them, put the car back on the dyno and tune all the other cars that where booked in after his?

Im not saying the car would be on the dyno for 2 days...... they may spend 6 hours over 2 or 3 or 5 days in between jobs.

In saying that..... I have seen a car on a dyno for more than 1 day..... Fixing issues, just small ones. but then went 8.8@155..... No one seemed to complain about the bill?

Edited May 23, 2012 by HYPED6