4kRR Audi 4000 Rally Rig

[Wilford Brimley]

I didn't think TR30r turbos were THAT expensive. I had the chance to buy a pair of them for $750 a number of years back, with a pair of spare turbine housings for $50 a pop.

[vbares]

I've looked at the TR30r - $10k - $15k each. You should have bought those lol Might have been the same guy I was considering buying them from

[vbares]

ok - believe it or not I'm finally getting ready to start this thing - but in doing all the necessary due dilligence, I've discovered that my Cam timing graph is fawking wrong - if anyone would like to verify my thinking that would be GREAT!!!!

So here's the thing - motor turns clockwise, that means that as you look at the graph, after TDC would be to the right of the zero mark and BTDC to the left as well as BBDC to the right and ABDC to the left. My original graph shows this relationship backwards. So, re-adjusting to this thinking - which I believe to be correct is attached (BTW also figured out that each tooth on the cam gear on the chain = 30 degrees on the crank and every 20.3 degrees on the crank is = 1mm of valve movement, so moving by a tooth = ~1.5mm of valve lift)

[vbares]

in order to try to wrap my head around this - I built a model that shows the degrees of the crank and which stroke the piston is on. This helped my understand that the way I currently have the cams set, is exactly what you want:
1. Exhaust as piston begins descent on the intake stroke
2. both closed during compression and ignition stroke
3. no overlap when the intake and exhaust are open at the same time

Based on what we know regarding the duration open-to-close for each cam shaft as well as the lift, we can calculate that for the 7a exhaust, each degree of lift = .0985mm and for the 3b = .0798mm - given that we can build this model:

Intake and exhaust modeled by stroke type

IntakeExhaustbydegrees.jpg (210.69 KiB) Viewed 49699 times

this shows that the exhaust closes 12 degrees prior to the intake opening - there is no overlap and no danger of bending valves ...whew...

If anyone has thoughts on this - I'd love to hear about it

[vbares]

and there's more - in order to be able to tune at the dyno I've made a degree wheel that we can use to measure what's going on

2015-07-12 09.52.49.jpg (3.01 MiB) Viewed 49699 times

downside of the 3b intake manifold is that you need to remove the TB to remove the valve cover

[mr_aj_johnson]

Makes sense to me!

[audifreakjim]

This is awesome.

[dana]

this is really cool. Makes me sad to see you have that damn restrictor in there though. I suppose having that limitation is probably what is spurring you to geek out on this, so maybe its not so bad.

[vbares]

haha Dana - yep, trying to get as much value out of the relatively meager dollars I have compared to the big guns I'm racing against...I figure this information will help others and will certainly help me figure out what I need to do next...

[deaner]

I wonder how the "powers that be" would react to a petition to changing the restrictor rule for regional classes. There's absolutely no way a small "weekend" team can compete with the bigger guys on 34mm. Something like a lower octane pump gas rule or something to keep power down instead of cutting our nuts off...

[vbares]

Coupe Du Quebec was on the verge of instituting something along those lines - you either run 91 octane or race gas - but always through the restrictor. The concept being that the 'big dollar' teams would run race gas and the weekender teams would run 91 - 'evening' things out as far as $$'s go...the ONLY reason it didn't fly is that there weren't enough race gas guys to have a meaningful class - bottom line, they are thinking in the right direction - oh, and you had to pre-buy gas for the event and from the organizers supplier - the supplier would then pump gas into your car at fueling in the service park - that way they could control the fuel quality.

They are thinking in the right direction - its just a matter of time...how about we put some race gas in this beatch then ??

[deaner]

I like that they're trying other things. I can honestly see how that fueling setup wouldn't fly very far. I wouldn't have an issue buying fuel from the organization as long as it wasn't stupid expensive. To me, as a newb still building my car, that fawking restrictor always pisses me off lol. Everything surrounding the sport is stupid expensive and that little thing in more ways than one, throws a bunch more cost and work on top. The off-road dirty bike racing I do has a "sprtsmans class" where you can run whatever you want, you just don't get any points. Keeps the faster casual riders from mucking up the points chasers scores as well as being a home for the guys that don't care about points and just want the experience. Works pretty well. Most people don't have the funds to chase a rally series around the country and end up only getting to one or two events out of the year, while they beat the piss out of it at local events in between. I'd love to see an "open, non restrictor" class that doesn't pay points. Cap it with shitty pump gas and draw in more people who just want to sling gravel a couple times a year. Just my opinion..
I plan on running RWD at first in the dirt lol.



Have you looked at any of the smaller framed holsets?

[vbares]

US Performance Rally is overshadowed by very unfortunate spectator deaths that occurred in early 2000's - this led to SCCA dropping the sport altogether and lots of rules to make the sport 'safer' - the restrictor being one that would slow the cars down - agree or disagree - I don't see unlimited coming back with or without points

Prices were competitive on the fuel, perhaps 15% markup compared to a local station, which I would pay if it created better competition...

As for the holset, no, I've not looked at that - this particular turbo has been custom built by Hank Iroz specifically for a restricted application. We're going for lots of torque sooner - limited to about 250hp due to choke...we'll see after this weekend how the custom design works compared to a stock GTX2869 and a less efficient restrictor (I have numbers for that setup).

[mr_aj_johnson]

Heard the noises this morning! congrats on firing her up again.

[deaner]

I agree, I don't see it coming back either. Just sucks because it's hard for a smaller to team to be competitive with the big guys. Luckily I'm just doing it for fun so stock turbo and RWD weeeeee.

I'm interested to see what you and Hank come up with. Any details you can share yet?

[roortube]

I know I'm late to the game here, and it may not work for you, but...

Last year I got an in cylinder pressure transducer for my Verus...it has become the single most valuable tool that ai own for diagnosing engine performance issues. I use it for many things, most relevant to your cam timing issues, checking cam timing with out removing any parts. You can graph cylinder pressure with respect to time and learn all sorts of things. This has helped me index cams (both or individual), diagnose failed lifters, valves, sensors, etc. If you already own a scan tool that will stream data from your car and has the capability to receive input from one, the $250 will be well worth it

[vbares]

Very interesting albeit perhaps too late for this first go-around of tuning...which one did you buy?

[roortube]

I told the Snapon man I wanted one and he got it. I can check the part # next time I'm at work if you like.

[vbares]

no worries - I'm sure I can source one when we go back to the dyno...and here are the results from the dyno...and there are always people to recognize that have helped on the journey:

Marc Swanson - EFI Express - this guy knows his business, has been tuning quite some time and prefers to play it safe with YOUR engine, unless you tell him not to. In Rally, due to the changing conditions - I prefer a safe tune. Also, keep in mind, the numbers below were taken on the hottest day of the year in NE - intercooler was well heat soaked and I would expect even better values in the fall...but for those hot days, I'm safe...

Hank Iroz - for the EM and turbo - ignore the numbers in the sheet - He took a GTX2862 and built a GTX28?? - inlet is 40mm, lets call it a GTX2840 not sure what the largest part of the compressor wheel size is.

Randy @ precision balancing in Hudson, NH - built the bottom end, balanced the crank, FW, damper...

Malcom @ Series Motorsport - did all of my aluminum tig welding - great shop, very knowledgeable guy!

Rob Shydo - helping to design the new restrictor - he did all the math!

Haydn @ HT Motorsports - for putting that design in to a form the machine shop could deal with

Ok - this is the old numbers - GTX2862, STR log manifold, sub-optimal restrictor (but really not horrible):

vittorioGTX2862_partial_pull_boost_reduced_same_torque.png (135.5 KiB) Viewed 49525 times

Next is GTX2840 (IMS flavor), efficient restrictor, IMS small runner EM, 7A exhaust cam, 93octane:

vittorio_93_2869.png (90.24 KiB) Viewed 49525 times

Next is GTX2840 (IMS flavor), efficient restrictor, IMS small runner EM, 7A exhaust cam, 103octane:

vittorio_103_2869.png (74.24 KiB) Viewed 49525 times

And finally an overlay of all 3:

vittorio_all_overlayed.png (130.72 KiB) Viewed 49525 times

Conclusions:
Restrictor improved HP numbers 10%-20%
Small runner EM, 7A exhaust cam and custom turbo improved spoolby 10% on 93oct and 25% on 103 as well as smoothed the boost curve
103octane, awesome early power, 370 ftlb @3100 rpm.

Running 93oct still produces 350 ftlb around 3300 rpm, but for much longer than the 2871 - which is pretty good when having to make the choice between race fuel $$ and pump gas...

[alxdgr8]

Wow, that is some awesome spool and early torque numbers!

[WOMBAT]

Fantastic results! That's going to be a monster on stage..

[groff]

Video or it didn't happen.
Looking forward to sharing the same stages with this thing!!

[vbares]

See facey space for a video ;p

[PRY4SNO]

The gain under the curve is pretty incredible. For an application where powerband is key you've done very well.

[deaner]

Holy cow! Well done!