Das Beast: My E30 track / street build

[dvallis]

Went for my first drive yesterday in the newly dyno-tuned car. Wow! What a difference. With our previous "butt tuning" the engine ran strong but felt rough. Now it's super smooth.No hesitation at any RPM and the power comes on like a freight train. When you hit 4500 RPM it slams you back into into the seat like a punch in the chest from Mike Tyson. Had a long time BMW shop owner friend in the passenger seat and he was grinning like a maniac. I was fascinated by the change in boost behavior. With open loop the turbo seemed to meander its way to max boost. With closed loop control the boost gauge instantly snaps to target boost once you get around 4500 RPM.



I'm really happy with how the build turned out. Only gets even more fun from here.

[ForcedFirebird]

The rule change was actually GTS, my bad. Had to look at the Dyno rules for the classes. The way it's done now, each RPM number has a weight to it (xx power at 3000, xx power at 3500, xx power at 4000 etc, max RPM, max power RPM etc) and it gets run through a calculator to spit out it's corrected HP/WT...

https://community.drivenasa.com/topi...-re-gts-rules/

[dvallis]

Yes, our ST2 aspirations could be highly delusional. :-) Flash forward to Rob on the radio yelling "Drive faster!" Alternative is detune to 10 psi and load up with sand bags for ST3, LoL

[Digitalwave]

ST2 for an E30 is pretty crazy! Going to be running with some wicked fast cars.

John, what about the current rules would deter doing the "max power from 2,000 - 8,000 RPM" that you described? You can use average numbers if you want, or you can still claim just 1 peak number for ST/TT as long as it fits in the HP:WT for the class. Average actually works in your favor as it should lower the number. Still seems like you could use that de-tuned V10 method if you wanted.

[Mushi]

I'm still open to options. Have you seen a southbend clutch hold over 400 ft-lbs? If so, which one for M20?

I PMd you about the DKM. And it did handle 750WTQ and 800WHP.. Its cheaper and perfect for your power goal.

[dvallis]

I'm still open to options. Have you seen a southbend clutch hold over 400 ft-lbs? If so, which one for M20?

[zaq123]

Why SPEC? Southband is a better option IMHO.

[dvallis]

PM me a link. DKM says it doesn't fit M20

[Mushi]

Clutch options now is DKM twin disk for the m5x and do m5x starter.

[dvallis]

Now we're finally getting back to racing. My favorite book is Mark Donohue "The Unfair Advantage". He was one of the first racer / engineers. I suspect Randy's detuned V10 in the E46 is something Donohue would have loved.

Sounds like I need to get my act together on the power to weight and power band width. Going from 6:1 to 9:1 on every turn would truly suck :-)

[ForcedFirebird]

Yeah, I was gonna mention power/weight ratio, but figured you were already figuring stuff out - much less than 9:1 and the cars are a bear to drive. Also, that curve is going to hurt you competitively. You will need average power for your dyno sheets at NASA, and your avg will be high, but it's all up top. Ideally sacrifice upper end power and fluff the curve lower, it will be a better performing car.

You might be familiar with Epic Motorsports. Randy caused the TT rules to change as he put a v10 in his e46 and de-tuned it so it has the max power from like 2000-8000rpm. They used to use peak power until he was sweeping every event he entered, and adjusted his tune to whatever class he wanted to be in (he is also a phenomenal driver to boot, not discrediting that).

Not sure how much faster is will spool, there's so many dynamics in a build, but anything will help your numbers right now. At 4000rpm, your car is only making 18hp more than my n/a 9.4:1 2.7, but your doubles that at in about 1000rpm lol.

[dvallis]

"M20 Lawnmower". LoL. I'm familiar with the concept.

I think a 0.58 turbine with the power flattened out on top will be fine, as long as it spools faster. 375 HP puts us at the top of ST2 in NASA including a 0.9 penalty for <2600 lb and non DOT tires. I'd rather be there than the bottom of ST1.

What RPM would you expect the power to start coming on for a 0.58 turbine housing?

[Digitalwave]

Great numbers. Bummer about the clutch. It's always something.

[ForcedFirebird]

The layout on that graph is deceiving at first, but when you look at the RPM on the X-axis, you can see all the power comes in at ~5k. Not much fun on a circuit when you really only have ~1000rpm to work with.

The hairpin at Sebring would be a good example. By exiting in 2nd, you don't have much time before the limiter, or use 3rd and the RPM drops to about 3200 when hitting the accelerator, the car wouldn't even really be straight when all of a sudden you have 2x the power. Took me a long time to master that corner when I was in HPDE (one of the other guys used to call my car "the m20 lawnmower" lol).

When I mentioned flow, it's on the exhaust side. Going to a smaller turbine decreases max flow capability - on the exhaust side - so you get in a situation where the power level will flatten out up top since the smaller turbine can only allow so much through it. This is the reason a lot of BMW guys complain about boost creep - and they are using a tiny t3 .58 with a 62mm compressor which should go on a small displacement high revving engine. What you have is the opposite.

[dvallis]

'Bird, thanks for the explanation. Makes sense. We're running a Precision 6262 with T4 divided twin scroll turbine, 0.84 A/R exhaust housing, 62 mm wheel, 3-5/8" V-band flange. Talking to Precision, they offer a 0.68 or 0.58 T4 direct bolt-on replacement (see below) I think we'll go with the 0.58 to get this thing spooling fast as possible. The compressor is rated to 700 HP so will not run out of flow for ~400 HP. Precision gave me these MPNs which are not on the web site:

K-TH5862A: T4 tangential 0.58 A/R 62 mm wheel 3-5/8" flange
K-TH6862A: T4 tangential 0.68 A/R 62 mm wheel 3-5/8" flange

Here's KAMotors dyno for the Canyon Crusher V2, which this whole build was based on from waaaayyyy back when.