Turbo upgrade

[Alistair E]

I swore I would never do it, but I don't think I'll be able to stop myself.

The problem is, I don't understand enough about turbo specifications. I'm looking for about 350-400hp which I believe should be ok on original ABY rods. I understand that I will need to go with RS2 exhaust manifold, green injectors, RS2 intercooler, different turbo and a remap. Is there anything else I need such as uprated fuel pump? I've heard mention of changing cams and cam timing, is this necessary?

Next question is which turbo. I've been looking through old threads and from what I can tell, the concensus seems to be that the RS2 turbo is the most straightforward route. However, there now appears to be another contender, the Garrett GT2871R. Looking at the thread started by maRS2, it appears to be a straight match for the RS2 turbo. Does anybody have any recomendations?

Also, would someone try to explain, in layman's terms, the differences in hotsides, coldsides and compressor wheels. I understand that a turbo basically comes in two parts, the hotside which sits in the exhaust and the coldside which actually forces the air into the manifold (I hope I'm correct in this). I don't understand all the housing numbers and compressor wheel numbers and mixing different housings with different wheels.

Lastly, anyone selling any of the parts I will need.

Hope someone can help.

Thanks

Alistair

[S2central.net]

I've wanted to do an FAQ on this stuff Alistair for a while now... I'll try to make a start on it. Meantime if you do a google for 'how turbos work' or words to that effect you are sure to find some useful resources. Recommended reading is a book called 'Maximum Boost' by Corky Bell.

Also if you do a search for 'Turbology' on the forum you'll find a white paper I compiled some time ago about understanding some of this stuff. Its overdue an update actually with more info that I have gleamed along the way.


Paul

[Ross]

Great reading with Paul's turbology doc:

http://s2central.net/Turbology_v4.pdf

Paul, how much does it take to bribe you to finish the brake upgrade before you go about updating the docs

Alistair - I thought I was buying an 'out of the box' super-S2 that I'd never want/need to upgrade as well... I guess 300bhp isn't enough Here's a few comments on what I've found in my research:

Stock rods - safe for 525NM, after this you're really risking failure. HP, they're ok for ~420. Note, though the RS2 turbo is 'only' good for 370-380hp, it'll deliver rod-bending torque IRO 600NM. But it can be mapped conservatively to avoid such as disaster...

I believe a new fuel pump is in order, I'm using a Bosch 044 Motorsport which seems to be the popular choice. Not sure what the stock pump is good too.

Injectors, RS2 EM, RS2 IC, all good for your power range.

Cam is recommended, I understand the extra advance allows the engine to be mapped much more aggressively; I'm sure a search will turn up some info. Popular is the 7A Exhaust cam (again, what I have) though some have both cams changed.

You've not mentioned the Exhaust + clutch. Are you planning on any upgrades there?? The stock exhaust will be a major restriction; stock clutch will be OK but if it's worn already you might want to replace it with something designed for the extra power.

cheers
Ross

[Alistair E]

Paul

As Ross said, your turbology paper makes great reading but as you state at the beginning, it will need reading a number of times for it to sink in.

Ross

Thanks for the info and yes I was looking at the exhaust and clutch. At the moment I have no idea which clutch but I was looking at a Milltek RS2 system for the exhaust (mine's an Avant).

Alistair

[martinjs]

i would fit the 044 fuel pump alistair, im still using the stock one but its running right at its limit on an rs2 setup. You should be ok with stock rods, but as ross says, if you want lots of torque you could have troubles. Mine has 515nm so again is right at the limit lol
Depends on what your after regarding turbo? Do you want lots of power or lots of torque or best of both. Do you go to the redline lots?
HTH
martin

[Alistair E]

Don't tend to redline it a lot so I guess I'm looking more in the direction of increased torque. Having said that, I don't particularly want to start changing rods. Especially if I've got to find the cash for all the other parts.

Alistair

[Ross]

I'm currently pushing some reasonable torque (was 435NM, before the 7A ex cam was fitted...) on the stock turbo, and that gives a good push in the back. 515NM has to be awesome, and I'm sure you'd not be dissapointed with it! With an ABY, I'd just stick with that level of torque as you'd be paying alot more for not alot extra.

I'm doing the rods, only as I have a 3B and have to change the bearings + head gasket anyway. 600NM eyes-pinned-to-the-back-of-your-sockets here I come

I'm sure the milltek system would be ideal, I hear it sounds awesome too! 2.75"-3" turbo-back is what I imagine most would recommend. As per clutches, do some searching, try "sachs" and "sinter", I'm gonna try the clutchnet Carbon Fibre jobbie as it gets a good report; hear it's good for day-to-day driving yet copes with these levels of power/torque with ease.

Rgds
Ross

[Ski]

IM planning on rebuilding my engine within a year or so... but im cluleless

So i want to start early planning... purchased the clutch.. just need the rest hee hee..

i see a group buy for rods.. where would I get 7a cams from and bearings? buy new from vagparts? what have others done?

[WabTheKing]

pm azman he has a pair of 7a cams he may sell

[Ski]

I dont need any right this minute, im just asking where would u normally get some from? Im guessing azman has some brand new ones he dosnt need?

[stevieyid]

@Ross 435nm is very impressive especially with stock turbo. What mods have u got to get that? When mine was dynoed i only got 359nm? what bhp is yours running now?

[S2central.net]

I dyno'd my 'homefried' ABY at 430Nm and I know that Ross's car got the MRC touch when it was owned by a previous owner. Depending on health of the engine, turbo, ignition and fuel systems it is perfectly normal to see 410-430Nm (and 270-280bhp) on good software with an otherwise standard engine. Translates to about 1.3-1.4bar maximum boost depending on the weather !

It pays to do dyno tests in nothing lower than 4th gear - otherwise it can be hard to get sufficient load necessary to generate maximum boost.

Also - if you had serious heatsoak it would reduce performance ?

Gees but 359Nm is less than what a stock ABY should be providing in overboost mode.

Paul

[stevieyid]

Mine has had the MRC magic on it i did get 281hp though. I dont think i would get much heat soak from the two massive fans that QST has got. The only thing i can think that affected it was the fact i had a collapsed cat and part of it had forced it way down the pipe therefor restricting the flow. Now i have a 3'' catless exhaust some maybe i should get it done again. Also the thermostat not working probably had a bearing on that to.

[S2central.net]

Yeah - get a 2nd opinion now you have fixed the exhaust and thermostat. With the same MRC touch as Ross's car you should be on the same spec as he is... give or take engine differences and the dyno's themselves of course.

[Alistair E]

Gt2871 / K26

Having never had the original turbo off the car, can someone tell me how the various bits fit together. Is it possible to build a gt2871r / k26 by buying the components individually? If so, which parts are k26 and which are gt2871, can someone provide a list such as
turbine housing
turbine wheel and size
centre housing
compressor housing (.63ar)
compressor wheel
spindle

Hopefully, this is not a ridiculous question

Alistair