4kRR Audi 4000 Rally Rig

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4kRR Audi 4000 Rally Rig

Postby vbares » Mon May 19, 2014 11:32 am

Time to start a build thread for phase 3 of the rally rig:

Phase 1 - purchase in 2009 as a 10VT 4K, 2-piece conversion suspension with big springs and Bilstein HD's - otherwise stock
Phase 2 - 20VT, new wiring, JVAB 50mm Bilstein, Porchse 944 intercooler, V8 oil cooler, k24 (3), GT2871 (2), GTX2860(1)
-- Blew 3 K24's
-- Melted a motor, rod knock
-- Found a 20yr old crate motor from EFI Express (thanks Marc)
-- Due to an unfortunate blockage in the oil restrictor for the turbo - blew GT2871 #1
-- After Dyno on a new GT2871, decided we needed to go to a smaller turbo - so GT2871 is now in a box :)

Phase 3:

Why would I need a phase 3?
-- Blew the turbo in October at Charlevox - seems there was a boost hose disconnected, turbo was overspinning, moment of cavitation, turbo bearings and cage explode and regurgitate into the oil pan, pickup sucks debris into oil pump, seizes oil pump, toasts engine. Oh, and just before Charlevoice - the night before, found a cracked EM with bits missing (replaced in time for rally) - who knows how that participated in the demise of both turbo and motor?

Plan:
-- Motor rebuild (thank you Randall at Precision Balancing)
+ Weisco Forged Pistons 0.20 over
+ JE Rods
+ Coated Bearings
+ New Oil Pump
+ New Squirters
+ rotating assembly balanced
+ Valve Job and light deck
-- Refurbish Radiator
-- Make calculations to determine what the best turbo is, given the 32mm restrictor
+ New restrictor with proper design
-- Accusump
-- New Oil Cooler
-- New EM (Wagner cast or IROZ tubular)
-- New DP is most likely required
-- Dump valve rather than recirc (gives more flexibility for piping and expected length of new restrictor)

Goal:
-- Reliability
-- Maximize Boost as early as possible
-- Moah torque!
-- Try to maintain theoretical max of 250 or so hp
-- Can we get close to 400 ft/lb of torque and remain reliable on pump gas?
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Re: 4kRR Audi 4000 Rally Rig

Postby WOMBAT » Mon May 19, 2014 1:37 pm

I like this. Will be watching for obvious reasons 8)
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Re: 4kRR Audi 4000 Rally Rig

Postby PRY4SNO » Mon May 19, 2014 4:04 pm

Cool project!

Maybe an aerocharger will suit your needs?
http://aerocharger.com/aerochargers/

Otherwise, BW has a cool site for sizing turbos.
http://www.turbos.bwauto.com/aftermarket/matchbot.aspx
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon May 19, 2014 10:38 pm

Here's what I've got so far on the Turbo with restrictor:

@32mm choke, reaching M1 we have a theoretical max Mass Air Flow of 25.6 lb/min = ~max 250 hp

Given that I've come up with the following table:

FlowPressure.jpg
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Keep in mind the Volumetric Efficiency (Ve) is a total guess and could be improved if anyone has the numbers.

What this shows is 2 things:
1) As expected Boost decreases as RPM's climb linearly
2) I'd like to be making 43 PSI of boost at 2500 RPM

Some WRC numbers:

With a 34mm restrictor the Ford Cosworth 2.0 litre version produced as much as 4.3 bar (47.87 psi) absolute at 2800rpm = 680 Nm (500 ft-lb) at 3000 rpm.

They achieved this using the Garrett TR30R (many dollaruni's to get in bed with one of these - like $15k) - here are some spec's:
Compressor housing: 
.60 A/R 
60mm inlet 
50mm outlet 

Compressor wheel: 
45.5mm Inducer 
69.4mm Exducer 

Turbine housing: 
.57 A/R 
50mm V-band inlet 
60mm V-band outlet 

Turbine wheel: 
59.3mm 
52.2mm 

Garrett also has a GTX2860R (Rally) about $5k each with these spec's (2nd spec is the non-rally GTX2860R):
GTXRallyVSNon.jpg
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Interesting here is the A/R on the turbine is zero for the rally version, and the inducer on the compressor side is almost 4mm smaller (this is probably to accept a restrictor without forcing a really sharp diffuser angle or a nasty step, causing a low pressure zone on the outer edge of the impeller blades) with the same size exducer diameter.

Borg Warner doesn't seem to have a small enough turbo to fit my needs - too bad in that I like the EFR line...

I may need to call Aerocharger to see what they're all about - and check rally rules to ensure variable vane is legal.

As you can see from the map of the rally turbo - the pressure ratio would be way off the reservation to achieve the boost I'd like at 2500 RPM:
GTX2860R.jpg
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So, the next step is to find a turbo with the closest numbers to what I'm looking for...
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon May 19, 2014 10:53 pm

Well, here's some good news - senility is starting to set in - its not a 32mm restrictor, its a 34mm and I'll need to re-calc...stay tuned.
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Re: 4kRR Audi 4000 Rally Rig

Postby Hank » Tue May 20, 2014 12:16 pm

Interesting read.

If you have any interest on building a more affordable 42/60mm compressor and housing that would bolt onto a standard 28r shaft/assembly, that is a project I might be interested in entertaining. It is insane that Garrett can charge 5k a turbo just because of the market.

I'd also love to get ahold of the $$$$ TR30r if you ever see any in the used market needing rebuilt or withing reason money(less than 2500). Another cool turbine that gets overlooked is the t25 30r turbine they are using in IWG turbos like thet IWG3071r. It is a 56mm inducer turbine instead of the standard 60mm turbine in the 30r. I always thought htat would be a fun turbo with a GTX or HTA71mm wheel in it.

Both would be too big for a race class on budget without antilag expense. I think you are on the right track with a 28 series turbine and a small 42-44mm inducer/ 60mm exducer wheel in a To4b compact housing.

Hank
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Re: 4kRR Audi 4000 Rally Rig

Postby mr_aj_johnson » Tue May 20, 2014 1:48 pm

How deep have you gotten into this VVT idea?
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Fri May 23, 2014 9:16 am

busy week!

Thanks to Rob Shydo for helping out on the calc's ! (the guy is a genius - really) :hail:

so, there are a few things to cover:
1. New Calcs
2. Hanks offer
3. Variable Vane

1. New Calcs based on 34mm restrictor

Max Air Flow @ Mach 1: 28.97 lb/min = max ~290hp
Max inlet pressure: 9.4 psi

MAP table:
MAP.jpg
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Pressure ratio's remain very similar - but boost requires grows - of course because we can flow more air and we're maxing out at 290hp

The turbine problem compounds, need moah soonah

2. Hank - I'm interested to see what magic you might be able to inject here.

As for Garrett, I would imagine they had an expensive engineer look at this, built a few prototypes, did some measurements and came up with the appropriate near perfect setup. Of course one might argue that the kit would need to change based on the engine and how it flows...None the less they probably want to recuperate their R&D plus they know the market will support that level of expense at the pointy end of the field.

My ability to stay at the pointy end of the field is currently limited to regional competition - I'd like to give nationals a shot - but fully realize that the differential technology at that level is going to leave me and my 4k lockers at a great disadvantage, oh and I'll probably buy new tires this year too, may be the least expensive upgrade I implement - but certainly my primary objective is reliability of whatever I put on the rig.

As for TR30R - I had found 2 a year and a half ago - guy wanted $1800 ea. for them as he was involved in some experimental lab where they let him keep the turbo after a small test - I wasn't of the mind set to spend that much on a turbo I couldn't easily replace. I've not looked for any since, for the same reasons...

I'll give you a call.

3. Variable Vane

No deep at all - I clicked on the link provided by PRY4SNO to the aerochargers site

Even though I like the idea in concept - and I understand this technology is used in diesels with pretty good success - I'm seeing some level of distrust from a reliability perspective ?

Also, aerochargers didn't have a turbo that matched what I'm looking for in their maps - seems like even for smaller engines, they have a very small pressure ratio range.
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Tue Jun 03, 2014 10:18 pm

Here's my CR assuming I use the 20v metal head gasket - which is pretty darned thick at 1.6mm compressed.

CC'ing the head:
2014-06-03 22.40.36.jpg
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Enter Bore/Stroke Designation Type  2 
1 = Inches 2 = Millimeters
Enter Cylinder Bore Size   81.5
Enter Piston Stroke Length   86.4
Enter Head Gasket Bore Diameter 83.0
Enter Compressed Head Gasket Thickness 1.6
Enter Combustion Chamber Volume In CCs 43.4
Enter Piston Dome Volume In CCs Negative For Dished Pistons (Use '-') 0
Enter Piston Deck Clearance Negative If ABOVE Deck (Use '-') : 0.2
        

    
Calculated Engine Compression Ratio 9.48 :1
Total Displacement Volume 53.1 cc

Pasted from <http://www.csgnetwork.com/compcalc.html>

If I drop the head gasket thickness by 0.5 mm I get to 9.94 : 1 CR

Any ideas on how I might get 0.5 mm thinner gasket? Does that even make sense or am I just looking for a reliability problem?

I have a paper 10vt gasket (not sure if all the ports align, but I suspect they do)...

Thoughts?
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Re: 4kRR Audi 4000 Rally Rig

Postby vt10vt » Wed Aug 20, 2014 8:48 pm

Drill out thw rivets in the hg and pull the metal spacer out. Pretty common in the vw world search around google and vortex.
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon Nov 03, 2014 1:09 am

Ok - been away for awhile - I've actually been learning about indexing cams on the 20vt. Long story short, there have been many discussions about what cams to run on 20vt - I don't want to re-hash those as my particular configuration is not geared towards biggest baddest power curve - but earliest spool, with a restrictor capping possible horsepower - so here's where I'm at in terms of cams - going to start with a 7a exhaust cam and a 3B intake. The idea being that we leave the 3b intake timing stock, but advance only the exhaust timing - how to do that? With adjustable gears on both cams:

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Intake adjustable gear
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Adjustable Exhaust (adjust this one changes both)
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    Timing Values @ 1mm
    7a Exhaust
    Open 42 deg
    Close 9 deg BTDC
    Duration 213 deg
    Lift 10.3mm

    3B Intake
    Open 3 deg ATDC
    Close 25 deg ABDC
    Duration 208 deg
    Lift 8.6mm

The adjustable intake timing gear did not have a TDC mark, so I needed to get both to a known point so we know what we're doing once we get to the dyno. What I've read so far is that spool can be tuned to come on earlier but you give up power on the top end. Since we have to run a restrictor, the top end is capped anyway and I figure this is a win...

Issues to get to a good measurement:
1. Finding an attachment for the dial gauge that is long and then. There's a very small area where you can get between the cam and the lifter surface to measure.
2. Getting a good zero measurement:
- Hydraulic lifters tend to squish if they don't have oil pressure keeping them pumped up, squish introduces random error in your measurements
- Solid lifters typically require machining and/or spacers to take up the lash - I believe the measurement is 14.7mm - my solution was to take the lifters apart as pictured and pour some oil in, then reassemble. This worked pretty well - I'm within 0.5 deg of factory spec on both intake and exhaust.

2014-10-26 16.11.57.jpg
lifter parts
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Lifter Plunger apart
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In order to get the plunger out - I whacked it on my wooden bench until the plunger came out - then the spring and internal cylinder come right apart. Put it back together and good to measure (I did buy a set of new lifters to complete the build). Poured some oil in it and put it back together - as long as there isn't a ton of pressure on it - the oil will stay in and provide a consistent measure.
3. It was exceedingly difficult to get the correct specs on the 7a exhaust cam - mostly because the Bentley is wrong and maybe there are multiple versions of the 7a exh cam - so there are multiple specs out there - one has a 219 degree duration and the other a 213 duration. The above specs are what my 7a cam shaft measured out to be - the key is that it has a 10.3mm lift (compared to the 3B 8.6mm lift).

Once I had these issues taken care of, indexing to spec was pretty straight forward. Looks like we can advance the exhaust 5 degrees and still have no overlap.


Next question was how to mark the intake adjustable cam so that we could make changes fairly easily on dyno day without the degree wheel. Solution was this cam degree wheel and pointer I found on the net @ http://www.20v-sauger-tuning.de/ - be aware that this sight also suggested indexing cams by removing the plunger altogether - this may be a translation problem - but clearly that doesn't work as it reduces the lift and changes all the measurements. Anyway by printing out the cam degree wheel and gluing it to some cardboard (still want to plastify each side of each piece), I can use the stock cam gear when at the dyno (will have to swap it in and out :thumbsdown: ) and move either cam, or both by a measured amount. Each degree on the Cam wheel=2 degrees on the crank.


CamIndex3b7a.jpg
Cam Index
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Last edited by vbares on Mon Nov 03, 2014 7:20 am, edited 2 times in total.
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon Nov 03, 2014 1:10 am

2014-11-02 15.27.37.jpg
Cam Wheel
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Awaiting Completion
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Re: 4kRR Audi 4000 Rally Rig

Postby deaner » Fri Mar 20, 2015 8:45 pm

So how's it coming along Mr.Bares?
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon Mar 30, 2015 7:15 am

Certainly making progress - we have some go-fast parts from Iroz Motorsports installed and should have a turbo next week. We then proceed to figuring out the restrictor and intake configuration.

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ensuring we are 100% level
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon Mar 30, 2015 7:18 am

2015-03-07 10.54.53.jpg
ensuring turbo will be level when building the DP
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Nice tight fit around the axle heat shield
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Re: 4kRR Audi 4000 Rally Rig

Postby deaner » Mon Mar 30, 2015 11:04 am

Looking good! Heard through the grapevine you're running new uprights these days too?
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Mon Mar 30, 2015 4:38 pm

Here you go...arm design and welding by Haydn Taylor Haydn Motorsports...excellent quality!

the inserts and bodies I sourced from Team O'Neil in Dalton, NH. They are a couple hours drive from my house and will take care of them when they need parts, rebuild, etc...

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Re: 4kRR Audi 4000 Rally Rig

Postby PRY4SNO » Mon Mar 30, 2015 4:43 pm

:drool:
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Re: 4kRR Audi 4000 Rally Rig

Postby deaner » Sun Apr 05, 2015 6:18 pm

Those look really nice! Are they bilstein 50s? I was hoping to get into a set of nicer boingers next winter but I think I'm going to hold off. First rally will more than likely be idaho, which from what I've heard is pretty smooth. I'm thinking of bigger tubed Bilsteins(urs/bbse) with an inch or so cut off the bumpstops and DIY coilovers with maybe 225lbs springs. How do you like your new setup so far? Compared to the green ones....
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Fri Apr 10, 2015 9:58 am

Yeah - 50s.

I got an additional 2" of travel in the front compared to the green ones - they should all be equal length front and rear - this was not the original thought.

The extra travel does make a difference keeping the steering wheels on the ground over bumps :)

I used billies before these - there's really no comparison as the travel can not be achieved with them. I agree you should just get out there with what you have - the billies are cheap to replace. I would bend at least 1 per event back in the day. But seat time is your best friend :)
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Re: 4kRR Audi 4000 Rally Rig

Postby mr_aj_johnson » Wed Apr 15, 2015 1:26 am

I'm pretty sure your and my green ones might not compare so well. The fronts have enough travel to just kiss the steering arm against top and bottom of the hole at full droop or compression. Looks like you might actually give a slightly healthier love tap under full compression up front? How long are your springs?

Droop just touches. Compression just kisses the top of the steering arm hole. right at or just shy of 8" of strut travel if I use my good eye ;)
Image


Didn't you go fling gravel on a closed course recently with a camera in the car? :hide:

I cant drive mine, even on tarmac without doing sideways things. Need to rebuild the steering rack as it's pissing fluid like a drunk on free beer night.
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Wed Apr 15, 2015 6:57 am

I'll measure the springs - but I remember they were 14" or so? I also just noticed that your arm looks a whole ton lower than mine - your rise from the shock body to the tie rod hole looks to be around 3" where mine looks like its around 7"...

Btw - since I swapped the ball joints left to right to push caster forward, the travel was allowing the tie rod to impact the inner fender well - so had to make some adjustments.
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Re: 4kRR Audi 4000 Rally Rig

Postby Mcstiff » Wed Apr 15, 2015 11:12 am

:drool: I need to talk to H about a street version for my 90 :-D
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Re: 4kRR Audi 4000 Rally Rig

Postby vbares » Wed Apr 15, 2015 12:20 pm

I think a street version is very simple - you can buy shorter inserts and shorter/stiffer springs - I'm thinking of doing this for a tarmac setup...
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Re: 4kRR Audi 4000 Rally Rig

Postby mr_aj_johnson » Wed Apr 15, 2015 3:40 pm

my arms are quite a bit lower than yours. had to in order to use all the available travel in the window. I haven't swapped bj's yet so good to know.
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