2.9 stroker pinging

[Sebastian35]

Engine pinging and need help!
block fitted with m52 crank and rods, pistons are +1mm JE and head is 885. Need advice!

[Kos]

try 99 ron fuel

failing that get it mapped

[Sebastian35]

I am using 99 already! just need to get it run in so an dyno can tune it.

[Brianmoooore]

DON'T POST THE SAME THREAD IN MORE THAN ONE FORUM!

[Gunni]

You need mapping.
Which I can sort out for you.

[Kos]

if you are running it in the you dont need to drive it hard ( in some peoples opinion ) any way try an octane booster, or get the timing backed off a bit

what compression are you running , it must be bloody high to be pinking

finally, gunni is the man when i comes to mapping these.

[Sebastian35]

DON'T POST THE SAME THREAD IN MORE THAN ONE FORUM!

Sorry I just wanted some help not stress for asking a question!
I wonder about this site sometimes as people can leap on you for such little things! Sorry sorry sorry!

[Sebastian35]

if you are running it in the you dont need to drive it hard ( in some peoples opinion ) any way try an octane booster, or get the timing backed off a bit

what compression are you running , it must be bloody high to be pinking

finally, gunni is the man when i comes to mapping these.

The pining was instant as soon as I pressed th gas, so i could not drive at all, by no means am i trying to drive hard yet. Just want to get moving lol. Now with the war chip I can move just lol and should be able to run it in! The compression should be 11.2.1 I did a CR test and it went off the gauge around 250+psi will check again tomorrow!
Thank for the info so far guys and I would love some help with that tune please....

[GeoffBob]

I did a CR test and it went off the gauge around 250+psi

Suggesting that you have a CR in excess of 18:1 No amount of tuning or additional octane will get you around this problem. You need to lower your compression ratio. Perform a compression test again with a quality gauge to be on the safe side and take it from there. If the numbers are as high as you say they are then don't even try to drive the car, you'll only damage your engine.

[CHR1S1990]

how did you get 18:1 geoff? I got somewhere between 10.3 and 11.5 depending on his choice of cam based on his cranking 250psi

[CHR1S1990]

should be getting between 210 and 240 PSI for 11.2:1, your cam being the varying factor

[CHR1S1990]

your reply has vanished geoff?

[GeoffBob]

How did you get 18:1 geoff?

By assuming a non-adiabatic process during compression Chris, an error on my part. Sebastian, please ignore my above post, I apologise for misleading you. I have a nasty habit of typing before thinking.

[GeoffBob]

your reply has vanished geoff?

By the time I finished typing my post you had already posted your next. It was then that I saw my mistake and took it down.

Are you assuming any heat lost to the cylinder walls in your calculation Chris (non-adiabatic process) or do you arrive at your value purely as a result of the delayed closing of the inlet valve (cam timing). No matter how I tried I could not arrive at your values. What value are you using for the ratio of specific heats?

[CHR1S1990]

No problem geoff, i thought somebody might have been tinkering with your posts thats all.

I was using a calculation i noted down a few months back I saw on the web:

Cranking Pressure (Psi) = CR^1.3 x 14.7 x 2/3

And.. as an estimate for cam overlap:

x .95 fast road cam
x .90 rally cam
x .85 full race cam

so for his 250 psi cranking pressure he should have seen somewhere between 10.3 and 11.5 CR
for his supposed 11.2 he should be looking between 212 and 238 PSI.

these are however, as youl agree, rough estimates as I am not sure how they arrived at the factors in the equation, or whether they take into account the adiabatic index. Im far from a mathematician/physicist as you can see, do you know a more accurate way of calculating the CR or vice versa? From what ive seen, you know your stuff!

[CHR1S1990]

edit: 1.3 is obviously the specific heat ratio

[Gunni]

I did a CR test and it went off the gauge around 250+psi

Suggesting that you have a CR in excess of 18:1 No amount of tuning or additional octane will get you around this problem. You need to lower your compression ratio. Perform a compression test again with a quality gauge to be on the safe side and take it from there. If the numbers are as high as you say they are then don't even try to drive the car, you'll only damage your engine.

I measured a M20B27 the other day and it measured more then 16bar. I have never seen anything like it, it made no more power then a kinda similar B27 that only measured in the 11s and they made about the same power at the same ignition advance.

The high pressure test one didn´t have any issues with detonation either.

[CHR1S1990]

^ strange!

[CHR1S1990]

do you know the block/head specs gunni?

only thing i can think of is the obviously higher CR engine as an unsuited cam to be not making any more power?

[GeoffBob]

[Ziggy]

Apologies for the long post.

When you put that much effort into helping someone, the last thing you need to do is apologise!

[GeoffBob]

Apologies for the long post.

When you put that much effort into helping someone, the last thing you need to do is apologise!

Ta!

[CHR1S1990]

At the very least (ignoring all the maths) it should give you some indication that your problem is tuning only (assuming your measurements are correct).

thanks for that geoff, makes perfect sense.

a little more info on his cam choice and we could be more accurate, but either way it seems his CR is around that of what it should be based on his piston choice and as you say, tuning is way off in this case. Sebastian you can rest assured you dont need to strip the block apart [edit] assuming your compression gauge readings are correct

[GeoffBob]

a little more info on his cam choice and we could be more accurate

Indeed, and a more accurate pressure value given that he states:

I did a CR test and it went off the gauge around 250+psi

I’m assuming a gauge pressure of 250psi in my calculation given that’s where his gauge ended (the most accurate value he can give us). If the pressure was indeed higher then I would expect my estimate above to creep closer to the expected value.

but either way it seems his CR is around that of what it should be based on his piston choice and as you say, tuning is way off in this case. Sebastian you can rest assured you dont need to strip the block apart

For sure

[reggid]

[GeoffBob]

[GeoffBob]

To add to the above, it is worth mentioning that calculating the CR of this engine is a purely academic exercise in any case (and one for which I must take the blame for raising). The probability of detonation occurring is a function of the combustion pressure and temperature and is thus only related to the CR of an engine in the sense that an excessively high CR can potentially result in an excessively high combustion pressure after the fuel/air mixture has been ignited. If the cam is chosen such that it results in a low dynamic CR, despite a high static CR, thus maintaining the combustion pressure below that beyond which detonation would occur, then the high static CR indicates effectively nothing. If, on the other hand, it results in an excessively high combustion pressure then delaying (retarding) the ignition timing will ignite the mixture at a time when some of the compression pressure has receded as the piston progressively moves past TDC. The question is thus, more specifically, one of whether a compression pressure of 250 psi is one that can be brought under control (prevented from exceeding the detonation limit during combustion) purely by means of effective tuning of the ignition timing. My gut feel, as a result of my very limited exposure to high compression Honda engines, is that this is indeed manageable, but requires a fair degree more attention to detail than say a low compression engine recording only 170psi that would indeed be considered less likely to ever experience detonation.

[reggid]

[GeoffBob]

[reggid]

[Sebastian35]

I would just like to start with a big thank you guys! Away regularly with no net hence the random input. Now then I brought the cam from top end in the US along with Je pistons connected via m52 rods and m52 crank, sadly they must think I want a refund or something as I have no response from them! All I know I have some issues and not sure what direction to go in. A little info from them would have been nice. Correction parts will be brought else where nevertheless. Meanwhile i have Been playing with the miller chip and I have managed to get it running and should be able to gently run it in, Hopefully! timing has to be retarded somewhat and some v power fuel and tetra boost has helped pinging! Making 5 star is not where I want to be lol but I can at least run it in.

is there a way I can check cam profile? I have a dti gauge ect. I can say the profile was bigger than the standard, also a VE pulley is fitted but set to 0 Should I retard this to reduce the dynamic comp? As soon as I can I will invest in a good compression gauge and see what the compression of my warm engine is. If the cam is Wong can that really make the difference or is it just a power thing?

Thanks again all for you interest and help so far.

[Sebastian35]

[Sebastian35]

[Sebastian35]

[Sebastian35]

a little more info on his cam choice and we could be more accurate

Indeed, and a more accurate pressure value given that he states:

I did a CR test and it went off the gauge around 250+psi

Seb here my gauge is 300psi and the engine was cold!
I’m assuming a gauge pressure of 250psi in my calculation given that’s where his gauge ended (the most accurate value he can give us). If the pressure was indeed higher then I would expect my estimate above to creep closer to the expected value.

but either way it seems his CR is around that of what it should be based on his piston choice and as you say, tuning is way off in this case. Sebastian you can rest assured you dont need to strip the block apart

For sure