Educated Guess At The Final Tune Results

[Nismo 3.2ish]

Just read the last 20 pages. A lot of people have thrown different theories around with explanations. Maybe they are right or wrong, but the discussions have been enjoyable and valuable I recon, even if we are all wrong.

I'm with you, there has been some good thoughts put on here , thanks

[Ben C34]

Pete needs a shot of nitrous and v cam to get the feeling of response he desires.

[XGTRX]

Turbo diesel

[AngryRB]

diff swap and VNT

Edited July 7, 2015 by AngryRB

[XKLABA]

Just read the last 20 pages. A lot of people have thrown different theories around with explanations. Maybe they are right or wrong, but the discussions have been enjoyable and valuable I recon, even if we are all wrong.

I have been reading, just not posting

Having theories is a good thing but the incorrect one should be recognised as incorrect to move focus to plausible issues so people aren't changing things that don't need to be changed

Like putting a GT42 or V cam on a car that the owner has all alone said he is after response with no shits given for top end

This setup should be at lot more responsive then it is easily beating a stock turboed GTR for response

As I said to Pete while I was there, fix what you know isn't right first before trying something you are not sure is incorrect

[Nismo 3.2ish]

As I said to Pete while I was there, fix what you know isn't right first before trying something you are not sure is incorrect

That has always been the plan Mick.

It will go on the Dyno to get another look at it and have a comparison Graph on the same Dyno for when the "final tune" is done

Then I guess he will work from there, eliminate the obvious, hopefully it will just be a tuning problem .

[jangles]

How do we know if the theory is incorrect if it hasn't yet been proven otherwise?

I would of thought the bigger dump/front pipe not making a difference was a good indication that the restriction is further up, ie. Turbo

[XKLABA]

The dyno graph is proof, because the the boost peaks then steadily falls away while the power continues to climb and then level out instead of falling off heavily as it would with the massive back pressure this theory implies

The theory would be under the assumption the excess pressure is only against the wastegate and not the turbine which is not the case the excess pressure is also pushing through the turbine increasing its speed and while this is happening on Peters car the boost signal to the wastegate is reducing which reduces the assistance the boost gives the wastegate spring to open the wastegate which increases the wastegate seat pressure which increases the manifold pressure and in turn the pressure at the turbine increasing turbine speed

Or is that wrong ?

[Shoota_77]

My head hurts! As was mentioned earlier, the actual discussion is fantastic as no one is really saying "I know this is the issue" more along the lines of "I believe it is..." so there is no need for anyone to be getting upset about another person offering a solution. It's great that everyone is willing to offer ideas as we've all had varying levels of experience chasing various issues. At the end of the day though, it's not until a decent tuner (that has nothing to hide unlike the previous tuner seems to have...) gets the car on the dyno and properly diagnoses the tune and setup that we're going to really find out what's going on.

One thing that I also need to add is how f**king awesome it is that Peter is a 70 year old bloke with a love of the GT-R that he obviously gets a lot of enjoyment out of. Peter I take my hat off to you and can only hope that my balls don't shrivel up by the time I hit 70 and still have a passion for the amazing vehicle that the Skyline/GT-R is!

Keep up the great discussion, it's what being part of a forum is all about. A lot of you guys have a great amount of knowledge and it's great to be a part of but let's keep all knickers knotless!

[sky30]

The dyno graph is proof, because the the boost peaks then steadily falls away while the power continues to climb and then level out instead of falling off heavily as it would with the massive back pressure this theory implies

The theory would be under the assumption the excess pressure is only against the wastegate and not the turbine which is not the case the excess pressure is also pushing through the turbine increasing its speed and while this is happening on Peters car the boost signal to the wastegate is reducing which reduces the assistance the boost gives the wastegate spring to open the wastegate which increases the wastegate seat pressure which increases the manifold pressure and in turn the pressure at the turbine increasing turbine speed

Or is that wrong ?

Exactly, turbo speed cant drop like that if there is huge pressure in the manifold.

Compressor out of flow could

[fatz]

Any reason this hasn't been taken to jez's and fixed for 1/8th the cost?

Only read last 5 pages

[XKLABA]

Any reason this hasn't been taken to jez's and fixed for 1/8th the cost?

Only read last 5 pages

waiting for Jez to have time

[fatz]

waiting for Jez to have time

make sure he doesnt read this thread or he might charge extra

i would

[Nismo 3.2ish]

make sure he doesnt read this thread or he might charge extra

i would

I am glad you fell off your toy in your backyard , giving Jez bad ideas like that,LOL

[Nismo 3.2ish]

My head hurts! As was mentioned earlier, the actual discussion is fantastic as no one is really saying "I know this is the issue" more along the lines of "I believe it is..." so there is no need for anyone to be getting upset about another person offering a solution. It's great that everyone is willing to offer ideas as we've all had varying levels of experience chasing various issues. At the end of the day though, it's not until a decent tuner (that has nothing to hide unlike the previous tuner seems to have...) gets the car on the dyno and properly diagnoses the tune and setup that we're going to really find out what's going on.

One thing that I also need to add is how f**king awesome it is that Peter is a 70 year old bloke with a love of the GT-R that he obviously gets a lot of enjoyment out of. Peter I take my hat off to you and can only hope that my balls don't shrivel up by the time I hit 70 and still have a passion for the amazing vehicle that the Skyline/GT-R is!

Keep up the great discussion, it's what being part of a forum is all about. A lot of you guys have a great amount of knowledge and it's great to be a part of but let's keep all knickers knotless!

haha, your head hurts, mine fell off pages ago

[AngryRB]

I reckon what Lithium said, the 0.84 split housing is probably not big enough, i had one on a 3076 and they are small in comparison to an open 0.82...

On a 3.2L motor the retarding of cams would be to try and help the top end, if they were advanced and the boost didn't fall away ( assuming deliberately done) then it would be getting pretty hot with only 98 wouldn't it? When it was previously backfiring uptop , that might of been some ignition retard from knocking up top with a small rear housing?? You said it was running pretty rich which also would suggest they were trying to keep it cool cause was getting hot in there..

Edited July 8, 2015 by AngryRB

[XKLABA]

My head hurts! As was mentioned earlier, the actual discussion is fantastic as no one is really saying "I know this is the issue" more along the lines of "I believe it is..." so there is no need for anyone to be getting upset about another person offering a solution. It's great that everyone is willing to offer ideas as we've all had varying levels of experience chasing various issues. At the end of the day though, it's not until a decent tuner (that has nothing to hide unlike the previous tuner seems to have...) gets the car on the dyno and properly diagnoses the tune and setup that we're going to really find out what's going on.

One thing that I also need to add is how f**king awesome it is that Peter is a 70 year old bloke with a love of the GT-R that he obviously gets a lot of enjoyment out of. Peter I take my hat off to you and can only hope that my balls don't shrivel up by the time I hit 70 and still have a passion for the amazing vehicle that the Skyline/GT-R is!

Keep up the great discussion, it's what being part of a forum is all about. A lot of you guys have a great amount of knowledge and it's great to be a part of but let's keep all knickers knotless!

I to like the throwing around of ideas and theories but unless there is a for and against discussion for them then anyone that reads them that doesn't know leaves thinking they are correct, I think the power of these fors is the back and fourth discussion of theories and ideas

What I don't like and why I am selective in where I post is people that think they are always right and when someone says different or questions them they throw out an insult then throw a tantrum and get upset cause not everyone just automaticly agrees with them

[XGTRX]

The dyno graph is proof, because the the boost peaks then steadily falls away while the power continues to climb and then level out instead of falling off heavily as it would with the massive back pressure this theory implies

The theory would be under the assumption the excess pressure is only against the wastegate and not the turbine which is not the case the excess pressure is also pushing through the turbine increasing its speed and while this is happening on Peters car the boost signal to the wastegate is reducing which reduces the assistance the boost gives the wastegate spring to open the wastegate which increases the wastegate seat pressure which increases the manifold pressure and in turn the pressure at the turbine increasing turbine speed

Or is that wrong ?

You are making a lot of assumptions as we all are.

If there was excessive back pressure and the gas speed is slowed it would have the same effect but will be more detrimental to the engine.

If the turbine is slowed the boost will drop, that's why we have a wastegate gate and the power still rises with rpm.

But the gate is open by exhaust gas in the manifold, not the boost controller so you can set the controller however u want but the turbo's rear is too small and can't flow enough to evacuate gases which results in a power ceiling and also a gradual reduction in boost.

The fact that boost had to be reduced to settle the other issues supports this to a point.

So in response to Pete questioning why he can't have more power, well that was the rationale because they can't increase boost safely.

The comment about a GT42 was merely to illustrate that people with bigger turbos don't have the issues like he is having.

But he loves the response of his set up, no one is telling him to change it, he just asked many 'why' questions and theories we share and hopefully JEZ can sort it out for him, and when they do we can learn something.

I would be a great car to drive regardless.

[QUP29]

feel sorry for u Pete, if only CRD would just answer your questions, most of your issues would be sorted.

Very poor form CRD!

[Nismo 3.2ish]

I think I must have given the wrong impression about power, everyone questioned the power I had, I did not have an expectation of much more than what I ended up with , I had spoken to the builder and he said it would be around 400kw and it was, 386.9kw.

But I questioned where the power is and why it drops off. I mean you cannot get any thing spinning at a 5k or 6000rpm launch, a little slip and thats it ,( I do not want to disappear in a cloud of smoke, but ?) I guess it is because the boost has already started to fall off at 4500rpm , maybe also because of better 4WD traction and good rubber, I thought 380KW would be mad

If it is a bolt on problem, I can change whatever is needed.

But the main thing is to get it in the shop and see how it goes with the mods it has now and see if anything shows up on the Dyno.

He has also used the PT6262 on his stock RB26 and is at full boost around 4300rpm , so he should have an idea how to get the best out of it.