Ideal Compression Ratio - 350 to 500bhp

[driftin jo]

I am not talking about when timing is being pulled. I'm talking about when Not being pulled. Theoretically you are saying that the 8:1 will be able to run more timing everywhere on the map.

I have stated my top and middle range timing. Perhaps Dmitri can add to this if he thinks more power will be made with a different compression adding more timing to that.

post #6

[A80Avant]

post #6

Obviously I disagree

And as far as Dmitri I'm referring to the timing degs I have stated after his post

[prj]

On any given psi when the engine is not knocking which will make higher torque? The 8 or 9 to 1 cr?

I run up to 41deg timing off boost and 20 on wot and 1.8bar which is the effective island of my FP at high revs and doesn't knock. I have plenty of timing in the midrange except on WOT. Would I gain more on having it 8:1 ? Also, do you run the car on WOT or nothing?

20 in the midrange at 1.8 bar without water meth on standard CR = molten 2.2T.
Or you have tons of blowby in the combustion chamber... or horrible VE.
Or... you are mapping with meth injection

What I am saying is that you cannot say to someone: do one or the other CR unless you know the rest of the parameters of the engine. Hence if for my setup I had less CR I would have lost top end and gained a bit of torque in the midrange. Lose top end due to the fact that although it may not knock because of the CR, the fact that the turbo is off the chart it would not make much more power anyway.

For what is worth that's my setup and that is how its been and worked fine. In my view a car is not made to go from idle to WOT while the in between map is useless.

Okay, engine basics.
You have a TURBO engine. A TURBO engine has a TURBOcharger.
On a NA engine having a high CR is important because you always have ATMOSPHERIC pressure.

On an ideal TURBO engine when you are running 1 bar of boost you have DOUBLE the air to compress compared to a NA engine. Get it?
So if you had 8:1 static, with double the air, that'd be like 16:1 on a NA. With double the heat and so on... Obviously the figures aren't like this in the real world.

This "low CR low response" bull*** is the most repeated myth about turbo engines there is.
As long as you are knock limited (and you are knock limited just about everywhere when you go near the throttle on a 9.0:1 2.2T), you are losing power and responsiveness.

A 2.2T on standard fuel without WMI will NOT lose any power anywhere whatsoever when you are on throttle comparing stock to 8.0:1. Even if you go WOT at 1000 rpm, will the higher CR engine have less torque.

What you describe happens much lower on these engines. 7.0:1 and lower you start to feel sluggish off boost response, but not at 8.0:1. If you look around a little, you will see for example the Volvo V70R and S60R, making 300hp with very low boost, and 8.5:1 CR.

But in the end, do whatever you want... can't look after all of 'em.

[A80Avant]

20 in the midrange at 1.8 bar without water meth on standard CR = molten 2.2T.
Or you have tons of blowby in the combustion chamber... or horrible VE.
Or... you are mapping with meth injection



Okay, engine basics.
You have a TURBO engine. A TURBO engine has a TURBOcharger.
On a NA engine having a high CR is important because you always have ATMOSPHERIC pressure.

On an ideal TURBO engine when you are running 1 bar of boost you have DOUBLE the air to compress compared to a NA engine. Get it?
So if you had 8:1 static, with double the air, that'd be like 16:1 on a NA. With double the heat and so on... Obviously the figures aren't like this in the real world.

This "low CR low response" bull*** is the most repeated myth about turbo engines there is.
As long as you are knock limited (and you are knock limited just about everywhere when you go near the throttle on a 9.0:1 2.2T), you are losing power and responsiveness.

A 2.2T on standard fuel without WMI will NOT lose any power anywhere whatsoever when you are on throttle comparing stock to 8.0:1. Even if you go WOT at 1000 rpm, will the higher CR engine have less torque.

What you describe happens much lower on these engines. 7.0:1 and lower you start to feel sluggish off boost response, but not at 8.0:1. If you look around a little, you will see for example the Volvo V70R and S60R, making 300hp with very low boost, and 8.5:1 CR.

But in the end, do whatever you want... can't look after all of 'em.

In fear of this becoming yet another one of the huge meaningless arguments with those who do not follow the prjism, but here is what I have to correct you on.

20deg is not on midrange timing but top end. 41 is off boost.

Now when it comes to your 'experience' I will return your basics and ask the rhetorical question: if 8:1 becomes 16:1 at 1bar of boost, then how much detonation do you have going to 18:1? Do you get ANY? And if YOU have detonation on the engines you have had the pleasure of tuning then it explains your beliefs. From the graphs you have uploaded on several of your maps I can see that your timing is not far different than mine and I have no knock whatsoever. So your assumption that anything near the throttle of 9:1 CR is simply a bad assumption.

Yes we do have a Turbo engine when the turbo is working and that is anything above atmospheric. Till then its a dull atmopsheric engine. The lower the compression the duller it is. So now we are going down to numbers. 8:1 is perfect. 7:1 is too low and yes will be duller off boost, and 9:1 is a fatal engine mistake.

Rusty, you are an intelligent person. I hope you get something out of this discussion. I know I have. Everytime I say what my car is doing, it seems as if it should have blown up years ago. My motronic map was crap and should have burnt my engine down, and with vems now I'm secretly running meth that I don't tell anyone to make me look as if I'm the best tuner around even though I don't do this for a living.

All in all what the truth about my engine is and has been.. oh well. I leave you to the realms of prjism

[prj]

In fear of this becoming yet another one of the huge meaningless arguments with those who do not follow the prjism, but here is what I have to correct you on.

20deg is not on midrange timing but top end. 41 is off boost.

Now when it comes to your 'experience' I will return your basics and ask the rhetorical question: if 8:1 becomes 16:1 at 1bar of boost, then how much detonation do you have going to 18:1? Do you get ANY? And if YOU have detonation on the engines you have had the pleasure of tuning then it explains your beliefs. From the graphs you have uploaded on several of your maps I can see that your timing is not far different than mine and I have no knock whatsoever. So your assumption that anything near the throttle of 9:1 CR is simply a bad assumption.

It is not an assumption it is fact.
A 8.0:1 CR engine with your boost could run 18 degrees in the midrange and about 28 on top.
That would make more power. Why do you think that 20 degrees on high rpm is MBT? It's not even close to MBT.

Why don't you advance your timing some more? Do you even know how timing is tuned?
Why do you think I have knock on 13-20 timing at 1.8 bar?

Yes we do have a Turbo engine when the turbo is working and that is anything above atmospheric. Till then its a dull atmopsheric engine. The lower the compression the duller it is. So now we are going down to numbers. 8:1 is perfect. 7:1 is too low and yes will be duller off boost, and 9:1 is a fatal engine mistake.

Rusty, you are an intelligent person. I hope you get something out of this discussion. I know I have. Everytime I say what my car is doing, it seems as if it should have blown up years ago. My motronic map was crap and should have burnt my engine down, and with vems now I'm secretly running meth that I don't tell anyone to make me look as if I'm the best tuner around even though I don't do this for a living.

All in all what the truth about my engine is and has been.. oh well. I leave you to the realms of prjism

Clearly, you have VEMS, so it is far superior to the Audi original ECU, and because of this your car can fly to the moon with 20:1 CR

[A80Avant]

It is not an assumption it is fact.
A 8.0:1 CR engine with your boost could run 18 degrees in the midrange and about 28 on top.
That would make more power. Why do you think that 20 degrees on high rpm is MBT? It's not even close to MBT.

Why don't you advance your timing some more? Do you even know how timing is tuned?
Why do you think I have knock on 13-20 timing at 1.8 bar?



Clearly, you have VEMS, so it is far superior to the Audi original ECU, and because of this your car can fly to the moon with 20:1 CR

Not one car you have tuned so far shows more than 14deg and 20-22deg at midrange and top end on full boost respectively and those have already CRs close to 8:1. Andy? Ross? Am I wrong? Show me one graph that you have 28deg at 1.9bar at 6500rpm and I will believe you. Show me the power it made as well and tell us the specs. I know enough about tuning timing. No need of your help. Thanks

The rest of your comments just show your age of a 6 year old. Maybe less. My nephew would probably like to play 'angry birds' with you sometime.

[prj]

P.S.

Knock free timing @ 1.8 bar, dyno tuned.

RPM   8:1   Stock
3000  12.75  8.25
3520  14.25  9.00
4000  17.25  9.75
4400  18.75 10.50
5000  21.00 10.50
5600  22.50 11.25
6120  24.00 12.75
6600  25.50 13.50
7000  26.25 14.25
7400  27.75 15.00

No water meth. 98 RON pump.

It really seems you have no understanding of how to tune timing though.
But please elaborate, how you tuned timing on your car.

[A80Avant]

P.S.

Knock free timing @ 1.8 bar.

RPM   8:1   Stock
3000  12.75  8.25
3520  14.25  9.00
4000  17.25  9.75
4400  18.75 10.50
5000  21.00 10.50
5600  22.50 11.25
6120  24.00 12.75
6600  25.50 13.50
7000  26.25 14.25
7400  27.75 15.00

No water meth. 98 RON pump.

Specs and power. Or it means nothing

And no I wont elaborate on anything. Its a secret. Remember? My car flies to the moon

[prj]

Clearly, whatever I type means nothing.
Only your internet claims, without any data are important.

It is enough for me, have fun.

P.S.
Guys, I am sorry, I was wrong. 8.0:1 CR is a horrible idea. You should skim the head and block, to achieve 10:1 CR, and your car will make 600hp with 1.5 bar boost.

[A80Avant]

Clearly, whatever I type means nothing.
Only your internet claims, without any data are important.

It is enough for me, have fun.

My data is all over the forum. You are posting something that could easily come out of your head. We have seen Sonic and Ross car and their numbers. Are they or are they not CR around 8:1? Is their timing as I stated above? Simple questions.

The numbers you posted are looking very good. So share the specs and lets see what it makes. Ill believe you.

[Mr30psi]

Clearly, whatever I type means nothing.
Only your internet claims, without any data are important.

It is enough for me, have fun.

P.S.
Guys, I am sorry, I was wrong. 8.0:1 CR is a horrible idea. You should skim the head and block, to achieve 10:1 CR, and your car will make 600hp with 1.5 bar boost.

Id love to see HP numbers actually. Cause throwing timing only is beneficial if were making power. just out of curiosity you retard timing under boost or advance it?

[Rusty]

PMSL @ the Angry Birds comment.

Discussion is good but please don't descend this thread into a slanging match...

[diesel des]

I have a feeling that on pump fuel and for 500bhp that 8:1 will be an easier tuned and "better" compression ratio than 9:1. But the real life results will show only marginal difference's. The efficiency difference is theoretically about 5%.

My stroker is going to be between 8.5 and 9:1 but my main fuel is LPG. If I was on pump fuel only I would goto 8:1. I will confirm my measured Cr when I get some stuff sorted in the next weeks. Dimeti like getting wound up about these small differences. Its all part of the fun...

Sent from my GT-N7105 using Tapatalk 2

[Error404]

I know nothing of the subject, so I will say nothing other than that today showed that Darren's motor at 8.5:1 is bang on the money for what you originally asked Andy, so surely can't be far from ideal

[prj]

I know nothing of the subject, so I will say nothing other than that today showed that Darren's motor at 8.5:1 is bang on the money for what you originally asked Andy, so surely can't be far from ideal

8.5:1 on water meth, just like I said in the very first post in this thread.