Best turbo upgrade

[MonkeyHanger]

You should know by now that there's no 'ish' in Denis' vocabulary!!

Of course, i'd forgotten about "Mr

[Speedy G]

Size? What diameter is the VR6 one?

I know mine uses an S3 tube (bigger diameter) and have seen the RS4 one which is massive. Scaling of mass airflow to match the software/tables is usually something to do with it.

Bill

The VR6, S3, and TT 225 all have the same MAF housing diameter. I think the diesel ones also have the 2.75" inner diameter one. The S4 has a 3" internal diameter. There are several reasons to increase the diameter (1-3 assume you get software upgrades with the larger housing):

I) Disclaimer: DO NOT INCREASE THE SIZE OF YOUR MAF HOUSING WITHOUT EITHER LARGER INJECTORS OR PROPER SOFTWARE, YOUR ENGINE WILL GO LEAN AND BOOM!!

1) More airflow needs bigger pipes.

2) The MAF sensor senses air velocity, the bigger the pipes the lower the velocity. Since the stock MAF sensor likes to see stock velocities in the order of 140-200g/s it's a good idea to maintain that range by increasing the size of the pipe when a larger turbo adds enough airflow.

3) Depending on the engine code, MAFs top out at different electrical maximums. My AGU one tops out around 180g/s I think, but I've heard of the newer engines topping out at like 240g/s. My MAF with a 3" housing sees only 150g/s but in reality there's 240g/s flowing (22psi to redline at 2800m altitude).

4) You can cheat the ECU into thinking there's only 150g/s of airflow, while in reality there's 240. The ECU therefore asks for less fuel, but since you added bigger injectors, the mix is still just right. This is good if you upgrade the injector flow in the same ratio as the MAF housing inner area. Like this:

Assume 270ml stock injectors & 2.36" ID stock MAF

440/270=1.63 so 440s have a 63% larger injector flow

(3/2)^2/(2.36/2)^2 = 2.25/1.3924 = 1.6159 so a 3"ID MAF has a 61% larger air flow area

Speedy G

[TaviaRS]

Thanks Bill and Speedy Top stuff.

Speedy, have you changed the FPR and/or the fuel pump to go with the larger injectors? I gather that the RS4 fuel pump is a good buy.

[badger5]

MAF is Mass Air Flow meter

g/s is Mass of airflow not velocity, grams per second, not velocity which would be meters per second type measurement.

Ratioing the incoming metered air to the injector sizes is what makes this setup work without software. Needs must and all that.....

[TaviaRS]

So, if I read that right, if I put a MAF in with a bigger ID and then increased the injector flow to match the new density figure, I'd be back where I started. Or am I missing something here?

Bill, you have a PM

[Ant]

Your fuel/air ratio would be back where you started, but there would be rather a lot moe fuel, & therefore more power

[redbaron]

can anyone point me in the direction of a highflow manifold to fit my GT25 to the RS when it finally returns from outer space.....?

[TaviaRS]

I know a man who will make you one. He's been making them for the last 25 years, does it as a hobby now and they are very, very good.

[Speedy G]

The comment on the MAF being a Mass Airflow meter is correct. g/s is a mass measure, but how does it work? There's a hot wire in the sensor element that measures essentially air velocity (collisions and momentum, actually but momentum is mv, and the mass of air known..). I have a paper on hot wire MAFs if anyone's interested. The sensor element is callibrated with the MAF housing ID, the air temperature and the atmospheric pressure in the ECU to really get a mass airflow reading. So you see, if you change any of those variables, you can alter what the ECU sees as mass airflow. It's not like the MAF grabs each gulp of air, then measures it's mass, then passes it on to the turbo...

In any case. The whole point of changing the MAF and the injectors is that before you could flow 270ml at maximum load. Now you can flow 440ml at maximum load which is a lot higher due to the larger turbo. What I'm saying is that since you have more air from a turbo, you can squirt more fuel to make more powe. This just moves the normal operating load of the engine (as the ECU sees it) up by 60%. What's the catch? Well RS Octavias and others with the DBW (those usually have a MAP sensor), have a MAP sensor, or more accurately a pressure sensor on top of the intercooler. If you have one of those, not only do you need to cheat ECU with the MAF but you also need to add a zener diode on the MAP so that you won't get an overboost fault code and go into limp mode. Since I don't have a MAP I didn't have to deal with that. People on vortex have made close to 400whp using this method, and running k03 chips.

Speedy G

[DGW]

Don't do it, Jon! :shocked:

[MonkeyHanger]

Don't do it, Jon![/b'] :shocked:

But we all know he will !

[Neo_VR]

The comment on the MAF being a Mass Airflow meter is correct. g/s is a mass measure' date=' but how does it work? There's a hot wire in the sensor element that measures essentially air velocity (collisions and momentum, actually but momentum is mv, and the mass of air known..). I have a paper on hot wire MAFs if anyone's interested. The sensor element is callibrated with the MAF housing ID, the air temperature and the atmospheric pressure in the ECU to really get a mass airflow reading. So you see, if you change any of those variables, you can alter what the ECU sees as mass airflow. It's not like the MAF grabs each gulp of air, then measures it's mass, then passes it on to the turbo...

In any case. The whole point of changing the MAF and the injectors is that before you could flow 270ml at maximum load. Now you can flow 440ml at maximum load which is a lot higher due to the larger turbo. What I'm saying is that since you have more air from a turbo, you can squirt more fuel to make more powe. This just moves the normal operating load of the engine (as the ECU sees it) up by 60%. What's the catch? Well RS Octavias and others with the DBW (those usually have a MAP sensor), have a MAP sensor, or more accurately a pressure sensor on top of the intercooler. If you have one of those, not only do you need to cheat ECU with the MAF but you also need to add a zener diode on the MAP so that you won't get an overboost fault code and go into limp mode. Since I don't have a MAP I didn't have to deal with that. People on vortex have made close to 400whp using this method, and running k03 chips.

Speedy G[/quote']

errrm... what just happened?

Ah... if its something Jon is planning, its ovbiously something insane

[TaviaRS]

Speedy,

What is a zenner diode and where do I get one from? I'm very interested in this Also, how is it wired in to the MAF?

One last question ( ) have you got a part number for the injectors? I've had a look round and have found a couple which might be suitable (although the flow rate may be a bit high) Looked at the 150351 which flows 590 @ 3 bar or possibly the 412911 that flows 800@ 2.5. I reckon the 590 is probably the best bet as I coulkd run the 4 bar FPR if needed.

Thanks in advance

[Speedy G]

A few things about injectors:

1) A 4 bar FPR makes the injectors flow more. Just like a turbo puts more pressure in the manifold thereby increasing air flow, a higher pressure FPR will make your injectors flow more. So running 590s at 4 bar you'd be increasing their flow rate to 680. Unless you want to run 680ml of flow, a 4 bar FPR is not a good idea. 680s are good for at least 410bhp. There's a good page for calculating injector flow:

http://www.rceng.com/technical.htm#WORKSHEET

2) The type of injectors that you need are hi-z or high impedance injectors. Those aren't easy to find in high flow specs. I've heard of 550s but that's about it. In any case if you plan on doing getto mods like the MAF and the zener, 440s will suit you fine. There's a guy on vortex that sold me my 380s his name is Scott Williams. He's pretty much in every thread that talks about injectors. 440s run for about USD200 from him plus shipping. I'm sure he could ship them out to you.

Now regarding the cheating of the ECU using a MAF housing and a zener on the MAP. If you're considering this, there's a ton of info on vortex on this topic in the 1.8t forum. I did the trick on my MAF but since I have no MAP sensor, I cannot say how it works. I suggest looking at threads on vortex by nerdhotrod and 1.8T3T04e. Both of them run about 380whp on k03 software with a T3/T4E turbo and a GT30R. Those guys really know what's going on.

The zener mod is pretty easy to do, I think, and one of them can run like a couple of USD. All you have to do is buy a zener diode with the right specs at an electronic components store (plenty of those in the UK btw). The install involves hooking up the zener diode to the two wires coming out of the MAP sensor. That's the sensor on top of the stock intercooler, in other words, not a MAF. What the zener does, is limit the maximum voltage the ECU will see from the MAP sensor. That means you can run 26psi and the ECU will only see 17psi. However, the downside to this is that you'll get more ignition advance which can lead to pinging. That's why the spec of the zener is important.

I do have to say that there are electronic gadgets that do the same as these getto mods and may make a cleaner install:

MAF "tuning": The Apexi S-AFC is made to control fueling by altering the MAF signal. The effect is the same as the larger MAF housing, but much more adjustable and costs USD300 more than a self-fabricated piece of PVC. The Apexi can adjust your fueling by +-50%. That means you can use 50% larger injectors. If you're running anything bigger than a GT25 or a T3 60 trim, you'll need to increase the MAF housing anyway, but the apexi is useful in getting a good idle and the right A/F mix.

MAP tuning: There are several products out there, usually called fuel cut defenders, FCDs or voltage clamps:

http://www.splitsec.com/products/clamps.htm

There's adjustable ones out there, I'm sure, you just have to look around if the MAP-zener bit seems too getto and are willing to spend the cash.

Remember that non of this is necessary if you're just thinking of going with a k04 or staying stock. If you're thinking of upgrading your turbo, a MAF and injectors would do the trick until you hit limp mode, then the zener/FCD begins to be important to be able to increase boost. Also, remember that turbos with less restrictive turbines, like a T3/T4E 50 trim stage III wheel .48A/R hot side, need less boost to make more power. You may find that 230whp is enough, and that can be done within the chipped k03 boost settings, so there's no need for a zener/FCD.

Good luck if you go for it! Oh, and I think 380whp can be done for less than the cost of an AMD K04 kit... not including and LSD though, which is a good idea.

Speedy G

[TaviaRS]

I have that last figure already Was looking at a "bit" more, so back to the thread title; which turbo?

I've looked at the IHI, the GT28R and the GT30. Any others I should consider? Have you got a compressor map for yours?

Edit: You changed your post! I have 231whp is what I meant, not the 320 :eek: Yet!

[Speedy G]

The GT28R is a good turbo, but you'll need an exhaust manifold to make real power. It has little lag and 300whp can be achieved with race fuel. I'll get your tires spinning. The GT30 is too laggy in my book, full boost by 5krpm. It can make a ton of power, but I'd go for a T3/T4E 50 trim .60A/R compressor and a stage 3 .48 A/R turbine instead. The T3/T4E can make more than 450bhp and gets full boost by 4.5krpm, sooner if you get the ball bearing option.

The IHI sounds like a good option though, but jabba is expensive. I'd love to hear more about IHI turbos and how they could potentially fit our cars. They're not expensive, they're low inertia and can handle some power, but I'm wondering if the ones available for the WRX would be too laggy for our cars. That's why some research needs to be done regarding the turbine specs of the IHI turbo used in the Jabba kit. I'm really curious about IHI turbos.

If anybody knows somebody at a porsche tuner, the K24 or K26 could be interesting if the hot side can be modified to a smaller A/R so that lag can be minimized. The turbine is what decides when a turbo spools up btw.

Mine is a T3 super 60, the compressor maps are on the turbonetics site:

http://64.225.76.178/catalog/compmaps/fig5.html

I don't recommend T3 turbos though. I made a mistake with it. Although it spools up quicker than a T3/T4E 40 trim, and is about the same size flow-wise, it's not efficient beyond 17psi. The T3/T4E 40 trim is a much better option.

Speedy G

[Speedy G]

Also, there's talk of the GT28RS on vortex. It can do 350hp with a little more lag than a GT28R. If 350hp isn't enough, a GT2871R can do 400hp with just a tad more lag. Those are all expensive turbos though, > USD1000.

Speedy G

[Leeboy]

Oh dear, there seems to be an opinion that the AmD K04 upgrade is rather on the expensive side - though lets not forget this includes full exhaust and cat, DV, and remap. A pity I would have to say, because I had this done to my motor in the Summer, before I came across Briskoda.net. Would I have sent the money in hindsight? Difficult to say.

The dyno plot gives 245bhp and at 263 ftlb of torque - near the limitations of the standard cogbox so I read elsewhere on this site. 'Coz I've not tried driving other uprated cars, i.e Jabba conversions/remaps I don't have anything to compare against - though I see may of your signatures quoting 230+bhp.

In defence of the money spent (before people reply and say I was stupid not to find briskoda before spending a considerable sum), pounds per grin factor for me have been worth it. Obviously, I would have been unimpressed if the difference was minimal. The car is very drivable around town or out on the open road. Masses of acceleration are available in all gears once revs pass 3000. I rather enjoy gently flexing the right foot on motorways to leave cars once hogging the rear view mirror behind, and truely marvel at 2nd gear acceleration 4000rpm to the red line.

I would certainly be very interested at track days/meets to see how other cars drive, and likewise people are free to test this AmD conversion.

Lee

[ColinD]

Well in defense, god knows we all pay for things sometimes. If your happy and I think you should be with that much torque..one hell of a good left foot in this chap me thinks, or shares in rubber plantations.

Anyway as you say it's alot, but alot comes with the package. Headline BHP is not the be all and end all.

I choose APR chipping (sorry of topic) over Jabba custom. I get a figure around 207BHP and 245'Lbs torque, a few other toys, like fault code erase, throttle body align etc etc it costs more for less than jabba...maybe so, but it was worth it for me...

We should all have a get together though wheres that driver training day thread?

re Turbos, Garret, good enough for the WRC teams, sounds good to me. speedy G, about to change your user text to font of knowledge, great info Sir. :liao:

[Speedy G]

I actually just think Euro prices in general are waaayyy too high. APR for example sells the stage III kit for USD4500 in the US, but GBP4000 in the UK. That's almost USD6900!!!! Then you guys have VAT... Pay me USD2400 to buy you a kit in the US and fly to Europe and install it for you. It would definitely be worth the trip for mechanics in the East of the US.

Regarding the AMD K04 kit, it sounds like a great kit for autocross. However, the GT28R kit from APR or ATP (USD2000) would do even better. I'm sure the price difference has to do with import tariffs and labour costs, but it's just sad that it's so overly expensive to get a few upgrades for your car in the UK/Euroland.

Speedy G

[badger5]

The comment on the MAF being a Mass Airflow meter is correct. g/s is a mass measure' date=' but how does it work? There's a hot wire in the sensor element that measures essentially air velocity (collisions and momentum, actually but momentum is mv, and the mass of air known..). I have a paper on hot wire MAFs if anyone's interested. The sensor element is callibrated with the MAF housing ID, the air temperature and the atmospheric pressure in the ECU to really get a mass airflow reading. So you see, if you change any of those variables, you can alter what the ECU sees as mass airflow. It's not like the MAF grabs each gulp of air, then measures it's mass, then passes it on to the turbo...

Speedy G[/quote']

Aye... and the company I work for makes thermal Mass Meters..... hot wire ones... Go figure!

[Speedy G]

Hmm... I wonder where I got confused with collimators... Yes the MAF measures airmass flow, not momentum, just re-read my paper. The hot wire is cooled by the collisions of the air with the hot wire, and more current is needed to heat the wire back to the specific temperature. The point is that it's still callibrated with a specific diameter MAF housing, temperature and pressure, although it self adjusts for pressure, I imagine within a specific range. So... you can still play with the MAF housing diameter as stated earlier to fool the ECU, which is what was being discussed.

Speedy G