Honey Badger's Completely Off-the-Rails Race Car Build and Track Adventure Thread

[oldbmwfan]

Alright - data is in! It's not great, but it's not terrible!

So to get it out of the way, apologies for the poor format for comparing. The reality is these were done 2 years apart, on 2 different dynos, with 2 different tuners. I just didn't have the ability to control these variables, unfortunately.

So this top image is for the motor with VCT. Runs breakdown as E85(top), VP100 (middle), and 93 tunes (bottom) I had for your average track day. These were quite de-tuned and conservative.

This image is from today with the cams locked out at 120 for the exhaust and 112 for the intakes.

As you can (sort of) see, the big differences are in the drop off at the very top and between 3,500 and 5,500. With VCT, we have about 360ish hp around 4,500. Without VCT, we're only around 320ish. Pretty big loss. And then there's the huge torque loss under 5k. Ha! But 5700-7600 is pretty similar. I'll keep reviewing and digging and share more.

Most of this is not a surprise. The main surprise was the dip up top. Notice how the VCT graph doesn't climb above 7600, but it stays level. Comparatively the VCT-delete motor falls off a decent amount from 7,500-8k. The tuner felt that we could move that up with some adjustment on the cams. I told Tim to optimize power where the stock cams make power and that's what I think we're seeing. Aftermarket cams could help fix this.

Hot takeaway: I am quite pleased how smooth the the pulls are given the lockouts. I expected a much bigger hitch around 5-6k. It's quite smooth. I'll be very curious to see what this motor feels like on track. Objectively it's pretty clearly worse, but my limited driving so far makes it feel pretty fun. We'll see what happens on Saturday on track

I've seen this with Vanos-delete BMW motors. It can "feel more fun" because what you feel is the inflection point in power gain, and you feel it as a kick in the seat as you accelerate but really what's happening is you're going from "worse" to "same," not "same" to "better." Like you, I'm quite surprised at the drop-off up-top and I hope that can be tuned out. The loss down low is pretty big, and it persists further up the rev band than I would have thought, but if you are mostly spinning the engine at 6K+, the losses below 5500 RPM might be a fair trade-off for reliability and durability.

 

[honeybadger]

Sorry if you've mentioned it already but what is the upside of locking out the VCT system? Love this build and how well you're documenting it.

There's honestly not that much. Mine has been as much an experiment as anything. Theoretically, it's more reliable because you reduce the number of "moving" parts. For me, I had some signs of deflection in the phasers that control the VCT and I went through a metric crap ton of solenoid plus/engine harnesses (particular weak point), so I decided to try it out.

For the general person, it's objectively considered a poor decision (and I'd agree with that).

I've seen this with Vanos-delete BMW motors. It can "feel more fun" because what you feel is the inflection point in power gain, and you feel it as a kick in the seat as you accelerate but really what's happening is you're going from "worse" to "same," not "same" to "better." Like you, I'm quite surprised at the drop-off up-top and I hope that can be tuned out. The loss down low is pretty big, and it persists further up the rev band than I would have thought, but if you are mostly spinning the engine at 6K+, the losses below 5500 RPM might be a fair trade-off for reliability and durability.

This is a good perspective. The extra character comes from a less smooth power curve. The peaky torque will likely amplify that as well.

Regarding the top end, the tuner felt we'd need to adjust the lockouts to get more out of it. He could've thrown more timing at it, but it would've reduced reliability. If I were to chase that, I'd rather dial in a set of cams to make power from 7,200 and up.

We'll see how this works out. I'll probably be driving a 500hp V8 like it's a miata engine

 

[honeybadger]

Two sessions down and so far so good. Absolutely screaming

 

[Hangman77]

Man that sounds good.

Since your running E85, I’m curious what the fuel consumption is going to be at the track on the 16 gallon tank. I know the E will burn faster.

Any thoughts on a cam? Custom ground? Or is there an off the shelf set you can buy?

 

[honeybadger]

Man that sounds good.

Since your running E85, I’m curious what the fuel consumption is going to be at the track on the 16 gallon tank. I know the E will burn faster.

Any thoughts on a cam? Custom ground? Or is there an off the shelf set you can buy?

It’ll oil starve under half a tank. At cota, I usually burn up 6 gallons in a 20-25 min session.

For cams. L&M Engines makes a pretty decent cam. I wouldn’t hesitate to run it. I’d only think a custom grind is needed when you do something like me and delete vct

 

[honeybadger]

Had a fairly wild ending to the day. Turned in to t13 and there was a pop, we spun, and the car ran over its own wheel. Ended up being a snapped UCA.

 

[ZX3ST]

Well that's TERRIFYING. Silver lining, there's way worse corners for that to happen in.

 

[Champale]

Man that is crazy! Thank goodness it didn't snap in the middle of a high speed corner.

 

[honeybadger]

Well that's TERRIFYING. Silver lining, there's way worse corners for that to happen in.

For sure. That’s probably the best turn to experience it. Lots of room for the speed. Thank god it didn’t happen in the carousel at 95+ mph

Man that is crazy! Thank goodness it didn't snap in the middle of a high speed corner.

For sure. Feeling might grateful. Ha

 

[JAJ]

Wow. You're lucky.

Have a look at SPC. Unbreakable and adjustable. Not quite as trick, but they won't let you down.

 

[Demonic]

Wow, glad you're ok. Could have seen that going much worse.

 

[Hack]

Looks like a fatigue failure to me. The outer shiny areas have been cracked for a while with the cracks slowly propogating along and the inner rough area just failed suddenly on track.

Please check the other side.

I was thinking about asking what the torque setting is but I see they are jam nuts and it's a little tougher to get those tightened to a specific torque. Is a crow foot wrench used to torque something like that?

 

[Hangman77]

Hopefully didn’t cause any other damage. Seems somewhat minor.

Like others already said you could have been at much higher speed during the failure.

Fix and keep racing.

 

[Lorne34]

Yikes! This track stuff looks dangerous! glad you are ok.

 

[NoXiDe]

Yikes! This track stuff looks dangerous! glad you are ok.

Don't let this deter you from participating. It's actually safer than driving on the highway and the part that broke was an aftermarket component. Although aftermarket, it could happen with OEM too.