RE: Skoda Octavia vRS Revo Technik: Driven
Discussion
A bigger compressor will indeed produce more cfm at the same pressure than a smaller compressor. I think AER meant so long as the engine can do something with all that extra air mass, then yes, it will make more power.
My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
SuperchargedVR6 said:
A bigger compressor will indeed produce more cfm at the same pressure than a smaller compressor. I think AER meant so long as the engine can do something with all that extra air mass, then yes, it will make more power.
My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
Is there actually any scientific reason why Revo's claims are unfounded and couldn't possibly be true? It's a bit hard from a layman's point of view to understand fully what is being said half the time. I also don't get the comparison with the Merc A Class. If a tuner like Revo for example has no concerns for things like C02 output's, MPG etc they instantly have an advantage that an official product cannot compete with. I'm sure Mercedes could get another 30Bhp from their engine if they were willing to make compromises but surely having competitive overall figures dictates how far a manufacturer can go. Or am I being naive?My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
ORD said:
Just from reading what people who know what their onions say, it seems like 200bhp per litre is a high enough specific output to give rise to reliability concerns. To put it in context, that would be a 600bhp M4 or a 720bhp 911.
I wonder what the measurable stats are for the FQ440?Scottie - NW said:
AER said:
Scottie - NW said:
When I ran a standard T28 at 1.2bar I struggled to make 288bhp, yet when I switched to a Garrett 2871 I only ran this at the same 1.2 bar (hadn't uprated the engine or fitted MHG etc as this point) controlled by an APexi AVCR electronic boost controller along with uprated actuator to hold base level, and at the same 1.2 bar, on the same rolling road, same mapper/operator and so on, even similar weather conditions the 288bhp became 323bhp
Several factors here: Firstly, rolling roads are not very repeatable, so there's a large error margin on the power delta you measured. Secondly, a more efficient compressor will yield lower IAT which increases charge density. More air mass equals more power potential. Thirdly, if you can reduce the exhaust backpressure, your internal EGR will be lower, enabling ignition advance to be closer to MBT (optimum) and most probably less enrichment for the same pre-turbine EGT limit. Both are conducive to more power.This is where I get confused. You are saying that a bigger turbo does not make more power at the same pressure level, but it seems a proven fact in car tuning that using a bigger turbo even at the same pressure makes more power.
If you read this thread it seems to be saying that pressure and flow are different things. The two main contributors "Mark" and "Zeppelin" both work on R&D for major motor manufacturers.
http://www.sxoc.com/vbb/showthread.php?585702-How-...
They are saying a bigger turbo will give more power at the same pressure level, and the results of tuning cars seems to bear this out.
If anyone can clear this up would be much appreciated
Cheers,
Scott.
The curious thing about aftermarket turbocharged cars being tested on rolling roads is that the more they are boosted, the more wildly optimistic the numbers seem to get. I strongly suspect some linearity error in rolling road testing, but I don't know what the mechanism might be that would cause this.
Conversely, on an engine dyno, the more you boost an engine, the worse things get in just about every way. Increasing power through increasing boost quickly becomes a law of diminishing returns.
gigglebug said:
ORD said:
Just from reading what people who know what their onions say, it seems like 200bhp per litre is a high enough specific output to give rise to reliability concerns. To put it in context, that would be a 600bhp M4 or a 720bhp 911.
I wonder what the measurable stats are for the FQ440?gigglebug said:
Is there actually any scientific reason why Revo's claims are unfounded and couldn't possibly be true? It's a bit hard from a layman's point of view to understand fully what is being said half the time...
Yes it is hard to understand, but the case has been put several times already. If you can't do the calculations yourself, you can't redibly dismiss them out of hand. The data has been presented earlier and so far, no-one has refuted it in any way, aside from waving dyno plots around. See above for my view on the accuracy of these measurements.AER said:
Seriously, I just wrote three reasons why a bigger turbocharger might yield more power at the same boost level. I won't be re-typing it again...
The curious thing about aftermarket turbocharged cars being tested on rolling roads is that the more they are boosted, the more wildly optimistic the numbers seem to get. I strongly suspect some linearity error in rolling road testing, but I don't know what the mechanism might be that would cause this.
Conversely, on an engine dyno, the more you boost an engine, the worse things get in just about every way. Increasing power through increasing boost quickly becomes a law of diminishing returns.
Ok I misread, I thought you'd said the three reasons would only produce a small gain, whereas they can be quite large, often over 100bhp more from going to a standard turbo to something like a 3071 or 3076 at the same boost level.The curious thing about aftermarket turbocharged cars being tested on rolling roads is that the more they are boosted, the more wildly optimistic the numbers seem to get. I strongly suspect some linearity error in rolling road testing, but I don't know what the mechanism might be that would cause this.
Conversely, on an engine dyno, the more you boost an engine, the worse things get in just about every way. Increasing power through increasing boost quickly becomes a law of diminishing returns.
Over a 2 year period of no changes to the car, and using same V power fuel and tyre pressures, I did various rolling road days, and the power output varied hugely from one to another, as much as 60bhp which as % of 400 is huge error margin.
I am really surprised at some of the comments I have read.
'What is the point of making a decent, performance orientated estate car even faster, why not buy a ?????????'.
I think it is brilliant to get dusted by something that you didn't expect.
Only thing that would bother me with the Octavia has been mentioned a few times, putting the power down.
We have a similar car to a standard Octavia VRS. Even with decent tyres on the front, if the road is slightly damp or greasy it will spin it's wheels for England.
'What is the point of making a decent, performance orientated estate car even faster, why not buy a ?????????'.
I think it is brilliant to get dusted by something that you didn't expect.
Only thing that would bother me with the Octavia has been mentioned a few times, putting the power down.
We have a similar car to a standard Octavia VRS. Even with decent tyres on the front, if the road is slightly damp or greasy it will spin it's wheels for England.
AER said:
Seriously, I just wrote three reasons why a bigger turbocharger might yield more power at the same boost level. I won't be re-typing it again...
The curious thing about aftermarket turbocharged cars being tested on rolling roads is that the more they are boosted, the more wildly optimistic the numbers seem to get. I strongly suspect some linearity error in rolling road testing, but I don't know what the mechanism might be that would cause this.
Conversely, on an engine dyno, the more you boost an engine, the worse things get in just about every way. Increasing power through increasing boost quickly becomes a law of diminishing returns.
Is there some sort of problem with people getting their head around dyno figures as of late on PH?The curious thing about aftermarket turbocharged cars being tested on rolling roads is that the more they are boosted, the more wildly optimistic the numbers seem to get. I strongly suspect some linearity error in rolling road testing, but I don't know what the mechanism might be that would cause this.
Conversely, on an engine dyno, the more you boost an engine, the worse things get in just about every way. Increasing power through increasing boost quickly becomes a law of diminishing returns.
No-one can just be happy for anothers successes. People always need to dig/imply that their figures are fake.
gigglebug said:
SuperchargedVR6 said:
A bigger compressor will indeed produce more cfm at the same pressure than a smaller compressor. I think AER meant so long as the engine can do something with all that extra air mass, then yes, it will make more power.
My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
Is there actually any scientific reason why Revo's claims are unfounded and couldn't possibly be true? It's a bit hard from a layman's point of view to understand fully what is being said half the time. I also don't get the comparison with the Merc A Class. If a tuner like Revo for example has no concerns for things like C02 output's, MPG etc they instantly have an advantage that an official product cannot compete with. I'm sure Mercedes could get another 30Bhp from their engine if they were willing to make compromises but surely having competitive overall figures dictates how far a manufacturer can go. Or am I being naive?My simplistic view of it is garden hose vs industrial hose. Run both at 2 bar. One will make you wet, the other will knock you over!
I found quite a lot more power when switching from a GT3071R turbo to a GT3582R. Obviously the onset of boost and torque curve changed, and the fuel map needed a tweak, but there were no other hardware changes.
Being a physical / visual learner, I need tangible proof. I haven't seen anything that I would call 'definitive' from either party yet, but burning dinosaurs has always been an area of inconsistencies and many variables.
The AMG scenario was an attempt to compare Revo's offering to one of a broadly similar setup that's currently available, and because tuning is their specialty, just like Revo. Looking at the numbers, AER's maths do seem to stack up. AMG won't have deliberately held back the performance in any way. They are not in the habit of producing engines that don't match or better their rivals. Look at the size of the exhaust downpipe on it compared to the VW's. They also changed the exhaust cam & ECU programming on the latest iteration and found an extra 21hp from the same turbo flow / pressure. I have no doubt in my mind they could get more from it, but I'm also confident they found it's peak / lifespan compromise. And it's warrantied for 3 years. What warranty do Revo offer on it's upgrade package?
I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
So yeah, that was a long winded way of saying there isn't any scientific proof either way
ORD said:
Do some googling. Dyno figures are almost always complete b
ks.
Can you prove that?ks.You are the one making the accusation.
Dynos give an indication of your cars output.
I don't think any claim to be accurate.
But if your car is making 250bhp it's not going to say 380bhp....... it may say 258 or 243 or something like that.
A dyno is simply a tool for measuring / monitoring changes. The numbers will never meet DIN standards.
Understanding dyno readings isn't made easy due to the different measurements they take either. KW, PS, BHP, HP etc etc.
As you say, if the numbers increase, the modifications worked and that should be all that matters.
Understanding dyno readings isn't made easy due to the different measurements they take either. KW, PS, BHP, HP etc etc.
As you say, if the numbers increase, the modifications worked and that should be all that matters.
SuperchargedVR6 said:
I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
That post was a good summary, but just to add re the bit about the intercooler, REVO confirmed in one of their posts the Skoda in this example has an uprated FMIC fitted but they forgot to include it in the PH article spec.SuperchargedVR6 said:
The AMG scenario was an attempt to compare Revo's offering to one of a broadly similar setup that's currently available, and because tuning is their specialty, just like Revo. Looking at the numbers, AER's maths do seem to stack up. AMG won't have deliberately held back the performance in any way. They are not in the habit of producing engines that don't match or better their rivals. Look at the size of the exhaust downpipe on it compared to the VW's. They also changed the exhaust cam & ECU programming on the latest iteration and found an extra 21hp from the same turbo flow / pressure. I have no doubt in my mind they could get more from it, but I'm also confident they found it's peak / lifespan compromise. And it's warrantied for 3 years. What warranty do Revo offer on it's upgrade package?
I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
Merc-AMG are a wholly-owned subsidiary of an OEM, so quite a different prospect to Revo.I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
You're comparing a production car, validated and homologated to production standards and requirements, to something from a much smaller; aftermarket tuning business. That clearly means that AMG are bound to certify their power output in a specific manner, and that they also have a clear warranty commitment which will also have a bearing on the power output. Thus AMG power claims are likely to be more conservative; and the power/lifespan compromise *may* be biased more towards the latter than for a Revo product, especially as Revo have openly said that they offer no hardware warranty with their upgrade package.
I'd not be surprised if AMG engineers in Revo's position could squeeze a bit more out of the AMG, were they not so constrained by OEM responsibilities/requirements. No doubt that if they stuck it on a hub dyno or rolling road and had some freedom around the test conditions that they'd also be able to 'find' some more power too.
The Octavia apparently does have a bigger intercooler - but I agree with your hunch that the AMG can deliver its power more repeatably. Being a non-OEM product is that an issue though? One of my toy cars is heavily boosted and would perform terribly across OEM performance validation tests at high temps or altitude, not to mention durability... However, I'm willing to accept those compromises in exchange for more performance across my narrower set of use-cases and requirements.
I still don't really get the issue, comparing a flywheel bhp figure from an OEM homologated test with that from an uncontrolled rolling road or hub dyno is never comparing apples with apples. Give Revo their due, they're quoting a power range for their tuning packages, not just a headline peak power figure that one car made once under perfect conditions - and provide before and after dyno plots by way of indication as to the percentage power increase.
Scottie - NW said:
That post was a good summary, but just to add re the bit about the intercooler, REVO confirmed in one of their posts the Skoda in this example has an uprated FMIC fitted but they forgot to include it in the PH article spec.
The amg has a charge cooler a very effective one to the point where nobody has manufactured an aftermarket one, the m133 also has some forged internals (probably crank and rods I'm not sure) this all goes in favour if you turn the wick up.SuperchargedVR6 said:
Well this is the problem. We have the vendor in the blue corner using dyno plots to argue their case, and in the red corner we have a PH member using maths to fight his. The classic salesman vs engineer stand-off isn't it.
Being a physical / visual learner, I need tangible proof. I haven't seen anything that I would call 'definitive' from either party yet, but burning dinosaurs has always been an area of inconsistencies and many variables.
The AMG scenario was an attempt to compare Revo's offering to one of a broadly similar setup that's currently available, and because tuning is their specialty, just like Revo. Looking at the numbers, AER's maths do seem to stack up. AMG won't have deliberately held back the performance in any way. They are not in the habit of producing engines that don't match or better their rivals. Look at the size of the exhaust downpipe on it compared to the VW's. They also changed the exhaust cam & ECU programming on the latest iteration and found an extra 21hp from the same turbo flow / pressure. I have no doubt in my mind they could get more from it, but I'm also confident they found it's peak / lifespan compromise. And it's warrantied for 3 years. What warranty do Revo offer on it's upgrade package?
I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
So yeah, that was a long winded way of saying there isn't any scientific proof either way
Cheers for the reply and thanks for making it as non patronizing as possible. It seems that some just can't help but talk down to others on here! Being a physical / visual learner, I need tangible proof. I haven't seen anything that I would call 'definitive' from either party yet, but burning dinosaurs has always been an area of inconsistencies and many variables.
The AMG scenario was an attempt to compare Revo's offering to one of a broadly similar setup that's currently available, and because tuning is their specialty, just like Revo. Looking at the numbers, AER's maths do seem to stack up. AMG won't have deliberately held back the performance in any way. They are not in the habit of producing engines that don't match or better their rivals. Look at the size of the exhaust downpipe on it compared to the VW's. They also changed the exhaust cam & ECU programming on the latest iteration and found an extra 21hp from the same turbo flow / pressure. I have no doubt in my mind they could get more from it, but I'm also confident they found it's peak / lifespan compromise. And it's warrantied for 3 years. What warranty do Revo offer on it's upgrade package?
I bet the AMG is more repeatable too as they will have used an intercooler that's up to the job. The Skoda's is still the same one the factory turbo / boost pressure required. As AER said, IAT has a big impact on torque.
So yeah, that was a long winded way of saying there isn't any scientific proof either way
Edited by gigglebug on Friday 19th February 14:04
AER said:
gigglebug said:
ORD said:
Just from reading what people who know what their onions say, it seems like 200bhp per litre is a high enough specific output to give rise to reliability concerns. To put it in context, that would be a 600bhp M4 or a 720bhp 911.
I wonder what the measurable stats are for the FQ440?Gassing Station | General Gassing | Top of Page | What's New | My Stuff