Pushing a near stock R33

[Lithium]

Hi all!

I am trying to improve the all around performance of my Spec2 R33 GTS25t while maintaining acceptable reliability, and not spending huge amounts of money or having the car being obviously fairly modified.

At the moment it has a 3" catback exhaust, Pod filter with cold air box (and ducting), removed charcoal canister a GFB bleed valve and an S-AFC2 which has been dyno tuned to run at 11psi, which I don't want to go past with the stock intercooler and turbo.

The thing I have noticed, that when looking at the boost plot from the dyno tuning - it reaches 10.5psi quite quickly (2400rpm), creeps out to a peak of 11.3psi (momentarily) at 4500rpm and by the time it reaches its peak power at 6600rpm the boost has dropped back off to about 9.5psi - where peak power is attained. The "base" dyno run I did for some reason peaked out at 13.6psi, and dropped back to a minimum of 11.5psi - interestingly enough that was before it had a bleed valve installed!?

Anyway - what I conclude from this, is that the factory wastegate is not much fun - and is obviously opening earlier than I want to, stopping the car from reaching 11psi straight away - but then after it reaches that peak it stays more open than it needs to be and the boost is dropping off, as opposed to the turbo running out of efficient flow. The most obvious sign that the car wants to push harder, is briefly as the boost is dropping - it levels off from its decline at around 10psi for a few hundred rpm between 6000 and 6500rpm and there is a corresponding increase in steepness of the power curve until the boost starts dropping again, where the power curve returns to being almost flattened off completely.

What I am thinking about doing, is installing an Apexi AVC-R and getting that tweaked to allow it to hit 11psi straight away (ie, ~2500rpm) and hold that until the end - in an effort to increase torque, and also keep the power curve climbing at the steady rate it appears to want to - possibly gaining me near 10kw @ wheels peak power, but most importantly having it so its not dropping boost in my "working area" of 4500rpm -> 7000rpm.

Question is, I hear the factory intercooler has quite a significant "pressure drop" across it - due to inefficiency more than cooling effect, and I don't want the poor stocky to be revving its nuts off to supply 11psi at high engine rpm through a restrictive intake system. Will this be a dangerous amount to push the turbo? Any experiences with Apexi AVC-Rs and boost behaviour using them?

Any help would be very appreciated

Dyno plot from the final tune at 11psi for reference should be attached:

[Guest Robo's]

Yes the stock turbo/actuator is giving you the restriction up high. But together with the stock cooler, this maybe a good thing. I was running 12.5psi with the stock cooler and this dropped to 10.5psi up high. With the fitment of a FMIC i gained a slight increase in boost up high, maybe .25/.5 psi. But i also gained a huge power increase.

Im not to familiar with the AVCR, but can you dial in 11psi down low and increase it 13psi, to get your plenum psi of 11??

[predator]

it sounds more like its just dropping timing as it senses detonation from the knock sensor??

larger intercooler should fix that, and add to the overall life of the engine.

[Munna]

Very interesting. I have a similar setup on my skyline. Full 3inch from turbo back exhaust, SAFC2, and bleeder set to 10psi, Stock turbo, and stock intercooler Boost starts dropping off up 5000 rpm, by 7000 rpm boost has dropped to 7.5 psi. But power still keeps climbing.

I also want to get a EBC to help hold boost but didn't even think about intercooler efficiency. If you put 1 boost guage before and 1 after the intercooler you could measure the presure drop accross the intercooler at certain boost levels. Eg. set boost to 12.5 psi (off guage After Cooler) by 7000 boost should be bakc to about 10psi. Watch the gauge before the intercooler to see what boost it is running if it is over 13.5 psi at any stage it would probably be unsafe to hold 10psi to redline with the stock cooler.

[Lithium]

Very interesting. I have a similar setup on my skyline. Full 3inch from turbo back exhaust, SAFC2, and bleeder set to 10psi, Stock turbo, and stock intercooler Boost starts dropping off up 5000 rpm, by 7000 rpm boost has dropped to 7.5 psi. But power still keeps climbing.  

I also want to get a EBC to help hold boost but didn't even think about intercooler efficiency. If you put 1 boost guage before and 1 after the intercooler you could measure the presure drop accross the intercooler at certain boost levels. Eg. set boost to 12.5 psi (off guage After Cooler) by 7000 boost should be bakc to about 10psi. Watch the gauge before the intercooler to see what boost it is running if it is over 13.5 psi at any stage it would probably be unsafe to hold 10psi to redline with the stock cooler.

Good point - that would be quite a good idea, though where is the "13.5" magic number defined? What pressure drop is it assuming etc? Shame its not feasible to attach a tacho to the turbo hehe Most people talking about 13.5 as measured at the plenum afaik.

I am just after 11psi (or even slightly less) right through the rev range, I'd just like more "area beneath the curve" - and think that up-and-down boost running isn't the best way about it.

[Munna]

Good point - that would be quite a good idea, though where is the "13.5" magic number defined?  What pressure drop is it assuming etc?  Shame its not feasible to attach a tacho to the turbo hehe  Most people talking about 13.5 as measured at the plenum afaik.

I am just after 11psi (or even slightly less) right through the rev range, I'd just like more "area beneath the curve" - and think that up-and-down boost running isn't the best way about it.

Basicaly I would like to know What the pressure drop accoss the the standard intercooler would be at 10psi with an engine speed of 7000rpm. If the guage on the turbo side of the intercooler read more than 13.5 psi I would fear for the life of the turbo. As it has to work to hard to produce 10psi, at 7000 rpm at the engine, with the standard intercooler.

[Jay95R33]

Could be a few things going on at the sametime.

Stock interheater restricting flow up high, stock dump pipe not liking the extra flow, and the stock actuator not being able to hold the extra boost up top.

Interestingly, I had a full 3 inch turbo back exhaust (highflow cat) and a front mount intercooler and I still got the boost drop up top. I would say that in my case the actuator was flapping open... Simple fix for the actuator is to put a stock R32 GTS-t one on as they hold 10psi well (that's their factory holding presure).

J

[benm]

Interesting, my boost isn't holding up top either. I was told by the workshop that it is because i'm using a bleed valve rather than EBC. My Mods:

R33 GTS-t S1

FMIC

Full 3" exhaust

3" Cat

TurboXS Dual stage bleed valve

K&N Panel Filter

Bosch 040

... everything else is stock standard. We turned the boost from 12psi -> 13psi and it didn't make any difference, it still settled on 10psi up top.

I'll be getting either an AVC-R or the P/FC Boost Controller addon when I get a PowerFC however that won't be until atleast the end of the year. Any ideas what it could be?

[Guest Robo's]

Its the actuator spring. Mine does it too.

[BOO57A]

The boost controler I am using is the setup from an article on AUTOSPEED.COM It uses an adjustable regulator and a pressure relief valve just like the ones u would use on an air compressor, but with a .8 bar spring not the standard 10 bar spring obviovsly. With this i have no loss of boost and zero wastegate creep.

I belive I have also read that sydneykid also has used this setup with good results and it will cost u under $100 to fit unlike those shitty name branded bleed valves that will spike and surge etc.

Cheers

Scott....

[Lithium]

Thanks for the input guys

It looks to me to be pretty much what I expected (seeing that people with FMICs and dp/fps have the problem too) which is that the factory wastegate is behind most of the problem, so I am guessing that an external (or replacement internal) wastegate would improve it a lot - though an AVC-R would probably do quite a good job of tricking it into holding boost as well.

Might have to nick a wastegate actuator from someones broken RB20DET turbo and experiment - we'll see

[Guest Robo's]

Actually i would like to try the RB20 actuator too. I dont know how much more power i would get if i can hold more boost up high, but certainly worth a try.

The HKS actuators are $275

[Lithium]

Actually i would like to try the RB20 actuator too.  I dont know how much more power i would get if i can hold more boost up high, but certainly worth a try.

The HKS actuators are $275

Well, seein as you are running 13psi (so probably drop to 10-11psi) - quite a bit from 4500rpm (where they seem to peak) up to 7000rpm based on the boost plots I got for my car. I should really scan them and post them.

From memory 1psi (slightly less even) boost at ~6700rpm gained me ~10rwkw at that point.

I got 202rwkw on 9psi, with 9psi coming at ~4500rpm and dropping to ~8.5 at peak power - and got 211rwkw peaking at 11psi @ 4500rpm, dropping to ~9.5 at peak power. Of course mid range still gets some pretty decent gains

[lwells]

I would be careful about modifying/replace the wastegate to hold boost for longer without a FMIC or someway of monitoring knock/detonation.

LW.

[benm]

The boost controler I am using is the setup from an article on AUTOSPEED.COM It uses an adjustable regulator and a pressure relief valve just like the ones u would use on an air compressor, but with a .8 bar spring not the standard 10 bar spring obviovsly. With this i have no loss of boost and zero wastegate creep.

Interesting, R33vit is using the same system. He showed me it a few months back at WSID and I didn't take that much notice of it (just another boost controller to me). He was raving about it with the same sorta response you have just given. I wonder if it would be worth my while swapping my TurboXS dual stage bleed valve for this AutoSpeed.com setup hrmmm.

Did you purchase the parts online or go to the Silverwater shop?

[Anquetil]

Can you please point me towards this article?

The boost controler I am using is the setup from an article on AUTOSPEED.COM It uses an adjustable regulator and a pressure relief valve just like the ones u would use on an air compressor, but with a .8 bar spring not the standard 10 bar spring obviovsly. With this i have no loss of boost and zero wastegate creep.

I belive I have also read that sydneykid also has used this setup with good results and it will cost u under $100 to fit unlike those shitty name branded bleed valves that will spike and surge etc.

Cheers

Scott....

[benm]

Part 1: here

Part 2: here

[Lithium]

I would be careful about modifying/replace the wastegate to hold boost for longer without a FMIC or someway of monitoring knock/detonation.

Yep, definately - the S-AFC2 has a knock readout, and I tend to mess around with settings on the dyno

[BOO57A]

Can you please point me towards this article?

Ill try and find the link for u.

BENM I brought the parts from a local phenumatics shop. The valves i use are made by Norgen and if i can find the article it has the part numbers including the numbers for the springs u have to change

[Anquetil]

Ta Ben...

• 1 x R07-200-RNKG Inline 07 ¼ Regulator Relieving 7Bar;
  

• 1 x V07-200-NNKG Inline 07 ¼ Relief Valve 7 Bar;
  
• 2 x 2069-02 07 Spring 0.7 Bar (brown);
  

BOO57A, so these are all relevant to Skylines as well, not just the Audi in the article?