Rustynuts 90Q RS Project.

[RustyNut]

Engine back in with Wagner IM installed. Still a few bits to tidy up but the need to get her running has taken priority now...

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Side shot of the Inlet Manifold.
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Pic from underside..
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Next step is to fit the intercooler and bracket. The dry run has revealed how difficult connecting the hoses to the intercooler is going to be! Ideally the outlet from the intercooler should have been fabricated facing back as there's barely enough room to install a Samco 3" 90 bend and the rest of the pipework to connect to the TB... It's the same the other side too with the route from the turbo to the IC being very tight. My only real issue now is positioning the MAF. The only spot for it is in between the air filter and turbo but most of this space is taken up by the headlight and the hoses running to the IC . We'll find out tomorrow when i've bought yet another selection of hoses if it's going to work!

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[Rusty]

Good work Russ, glad you're making progress

[BRY]

Nice work Russ.

[S2_Dave]

My only real issue now is positioning the MAF. The only spot for it is in between the air filter and turbo but most of this space is taken up by the headlight and the hoses running to the IC .

What about between the IC and reverse IM:

[Bram]

Nice stuff you have there

[RustyNut]

@S2-Dave - What you have there would be perfect but we're struggling to find the room (see pic below). If i had the facilities and know how to weld ally like that then I might be able to solve the problem because at the moment i'm limited by what Samco's can do... I bought a few more Samco bends and connectors today and i'm hoping once everything's connected we'll find a place for the MAF where you suggest. The second pic shows the turbo side and the amount of room available there. The turbo to IC connection is straight forward but we've then got to fit an air filter in there somewhere too. I think i need to find a competant ally pipe fabricator...

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Thanks for the comments so far chaps. This is my first attempt at anything like this and the whole thing has been a long time in the making. Neil and Alex are the brains behind the engine build - i just get in the way, work out what bits i need, pay for them, clean and paint stuff and make the tea . Really enjoying it though as i'm always there when the car is being worked on so i'm learning all the time. The thought of having a super quick 90q has always been my inspiration for the build. It's one of the best cars Audi ever built IMO

[RustyNut]

A bit more progress!
We've mounted the intercooler and bracket in their final position and had our first go at lining up the pipe work. At the moment we've only fitted Samco's and straight couplers to get an idea where the MAF, N75 and BOV can be mounted.

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Plan A was to have the MAF mounted in front of the Radiator as shown below. We've decided against this on the grounds that we would have to extend the cabling and there's more room in between the turbo and IC to mount it. Would also like to keep things simple on the IM side as the route to the throttle body is tricky enough without adding the MAF into the mix.

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However... This is where we need some advice on what we should do next. In the pic below you can see the gap between the two silicone tubes from the turbo and the IC which is where we intend to plumb in the Dump valve and the N75 wastegate valve. Problem is that we're stuck and don't really know exactly how to go about it . Has anyone got some pointers on the best way forward from here?

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I'll get a suitable length of alloy pipe and will have to find someone to weld on the necessary bits to connect the valves once we're clear on what's required.
As far as the MAF goes, we're going to mount that between the Air filter and turbo (there's more room than we expected) and try to get the filter to sit below the line of the exhaust manifold.

[RustyNut]

Right, having done some in depth research on the workings of the N75 i believe my above post was somewhat ignorant on my part. I assumed this stage would be pretty straight forward but i have now realised that I need to get this part of the build spot on or the whole thing will be a waste of time.
I've read through Pauls excellent write up in this thread ( http://www.s2forum.com/forum/showthr...&highlight=n75 ) and i'm now a little nearer the point where I understand what needs to be done.
My understanding so far is as follows:

1) I need a stiffer wastegate spring to match the pressure created by the 3071. Which spring should i use?
2) I need to connect the WGFV in the standard S2 format (Pauls logical layout). Port1 connected inbetween the MAF and cold side (compressor) of the turbo. Port2 connects to the wastegate lower chamber. Port3 connects directly to the compressor 'Air Out' side (does this mean i can form a connection in the pipe i mention above?).
Or 3) I go for Pauls alternative layout A or B? My preference would be Layout A which gives faster spool and less lag as opposed to max boost quicker. What layout would be recommended for my set-up bearing in mind i want to get the car remapped in a way that won't overly stress the major components (can't afford a rebuild!!)?
4) The TBV is connected inbetween the turbo and IC with a link to the Inlet Manifold (how is this linked?). Do i still need to go for a recirc valve or is it safe to go for a vent to atmosphere valve? Again i'd rather be cautious if there's any doubt.

I'll probably go for the Turbosmart WGFvalve which seems to be the valve of choice as a direct replacement for the OEM N75?

Have i understood the principles correctly or have i missed someting out?

Cheers

Russ

[RustyNut]

Quick update,

Finally got everything fitted, tightened, lubricated and clamped up on Saturday (i think i've kept the hose clip & silicone industry afloat getting everything jointed up properly!) and hoped that the old girl would fire back to life after all this time. But alas, she didn't....
We practically flattened a new battery trying everything we could to get her started but she just wouldn't go...
We checked everything over and these are our findings:
1 - For some reason the fuel pump is running constantly. Once the rail is primed it should stop pumping until the engine is started but it just keeps flowing? Not sure what this could be but at least we're getting fuel.
2 - The crank sensor isn't getting a signal.
3 - It is sparking.
4 - There's definately compression.
5 - We're getting a signal from the cam position sensor.
6 - The injectors are getting a signal.

At the moment we're a bit stumped... We're thinking there could be a problem with the pin on the flywheel so next saturday we're going to remove the gearbox to check but apart from that I could really do with some advice. neil checked all the wiring and everything appears to be as it should. Can anyone help?

Cheers

Russ

[GT500]

WHy not just take the starter off?

[Jenks]

Brian Tonks checked for evidence of the timing pin by poking small tyrap in through the relevant sensor hole and feeling for it being flicked by the pin when someone turned the engine over. The lack of 'flick' more or less convinced him that the pin was missing and that was confirmed when the gearbox was later removed.

Just thought, if you try this make sure you use the pointy end of the tyrap and for gods sake don't stick your finger in the hole!

[Rusty]

My immobilisor makes the fuel pump run constantly and not prime and I've had starting issues due to the crank sensor plug, as Neil will testify! It won't have spark without both crank position and cams position, crank speed is for running, not starting, which crank sensor is it? Grey, position, or black, speed, plug? Good luck with it.

[A80Avant]

something i realised for the 3071R 0.63AR turbo and boost recently with some logs...

trying to run 2bar of boost to the redline is useless.The turbo runs out of juice pretty much at 1.7bar after 6000rpm and starts to blow hot air instead. My IATs from 13-18C climb to 40C even with a 9C outside temperature.

In my case, having 0.72lamda after 6000rpm also maxes out the injectors (440cc) which is ok, but the mixture can get leaner with a bit of higher EGTs as well (more than 950C on the hotside).

In essence, using a stiffer wastegate spring will allow faster and higher boost,but you wont have high gains above 6000rpm. (unless you use cams that may push a bit more air in OR better exhaust to reduce the backpressure a bit, although most of it done by the hotside anyway).

[RustyNut]

Cheers for the replies, will try and check the timing pin as suggested. Could well be something really obvious but we won't know until Saturday.. Still a bit confuzzed by A80avant's reply?

[terrybullwon]

Cheers for the replies, will try and check the timing pin as suggested. Could well be something really obvious but we won't know until Saturday.. Still a bit confuzzed by A80avant's reply?

Hes just rambeling about the turbo you have. Like Gt500 said take the starter off to check for the timming pin. I am just about to send you those photo's mate