SCCA EMod MGB GT V12 Build

The Pink Panther is ready to race, whenever the season resumes. Here's a new video Episode 255 First drive of 2020

Wow, been a month since the last update. I pulled the car out of storage and went for the first event of the year and it was a double header. Day 1 wasn't perfect, the car had great handling and stopping but would stumble and nothing I could do would stop it. Despite that, I finished with fastest time of day and 7th in PAX. I got home and changed the oxygen sensor, cleaned the air cleaner and performed a pressure test of the intake system. Day 2 the car didn't stumble at all, but it didn't make boost, either. Again, I couldn't find or fix the problem so I just floored it everywhere and the car stuck. I finished with the 2nd quickest time. I got home and pulled things apart and checked a lot of stuff and found nothing obvious, until I checked the wastegate. It is an aftermarket wastegate and the pull rod had come loose, leaving the wastegate open all the time. I took it for a scoot around the neighborhood and it definitely made boost-yay!!  Episode 256 It's on rails!!

"17 or 18" C equals 62.5 - 64.5 degrees F.  

Unless there is lead in the fuel you use, I would not suspect the O2 sensor.  The simple fact that it's running tells me that it's hot- as it has to be to even run, and it knows it.  Could be there's stuff on it, and more heat will burn it off, perhaps.

But I would suspect the stumble to something else- not sure what, though.  

BTW, any intake leak would be "measured" by the MAP sensor, so it would be automatically compensated for.  A MAF meaurement would be problematic, though, if there was a leak.

In reply to alfadriver (Forum Supporter) :

I do use leaded fuel so O2 sensor is potentially a problem. The car does seem to be fixed now so either the air cleaner, O2 sensor or broken wastegate (or all 3) was the problem. I'll know more in a couple of weeks at the next event. It is really disappointing to have the whole winter to solve problems then have these things pop up at first event.

"nothing to see here occiphur"  SWEET!!!!

I had another event and made some changes to the car that proved to be dramatic. My aero guy had advised me that the new spoiler and splitter would give an unbalanced aero profile and lead to understeer. After the last event I realized he was right and I put my old rear spoiler on but kept the new, larger splitter. At the same time I tried moving my ballast forward to see what would happen and was rewarded with massive oversteer. Moving the ballast back restored the balance but not before I looped the car. Watch the video here

In reply to loosecannon :

it's interesting to hear how finely balanced the car is, that 30#'s... on, what(?), a ~30" arm can move the car from balanced, to oversteer, to 'whooooah-nelly oversteer'!

taking a step back, there's something tickling at my brain... it's not fully formed... but it strikes me that the rules seem to push the aero design into a corner where it's... difficult? complicated? to add in the ability to tune the front/rear aero balance.  I suspect part of that is the necessity to try and maximize the downforce.  and I suppose, there's the difficulty of isolating mechanical grip refinement from aero-grip refinement... especially with limited testing time/opportunities.

thanks for that episode.  the mic was a nice addition.  good luck!

In reply to sleepyhead the buffalo :

The aero rules were written back in the day based on guesswork. Maximizing the aero front and rear will give you far more rear downforce than front. The recent change from 6" splitter to 8" splitter was designed to address that but it hasn't gone far enough. We really need dive planes or diffusers on the front of the car. I wish they would do away with aero in EMod but that will not happen. I have a theory on car set up that the closer you get to the ideal chassis set up, the greater the effect of small changes to the set up. When my car had a bad set up, I could make big changes without much affect but now that I'm close, a couple of clicks on shock settings or moving ballast around makes a difference.

In reply to loosecannon :

I'm circling around a thought that at some point, you want to figure out a way to make the rear spoiler 'adjustable'.  I reckon you're right, that you're always going to be front-aero limited... so, it seems like fine-tuning the balance will have to come from adjustments on the rear.

Unfortunately, I don't know the rulebook well enough to come up with ideas of how to go about that.  And I have a feeling 'adjustable rear spoiler' is going to end up being more be along the lines of 'have 6 different spoilers stored in the trailer to change between'... and not "tweak the angle, and/or swap the gurney", as you see in other series.

In reply to loosecannon :

Just a thought?  Maybe the problem is the MGB nose? It's rather blunt.  Wouldn't a lower front aide in getting front downforce?  
Since your body is just a fiberglass replica what about a different front? Maybe something more slippery?  
I'm just spitballing  But here's an interesting fact, the MGB and the Jaguar XKE have the same front track. 50 inches.  Or maybe you'd like a Spitfire or Mazda RX7? 

  I've seen cheap Chinese made chopper guns for spraying fiberglass.  They work and they are cheap.
make a plug as a pattern use stock (ish) parts.  cover rust holes with tape and bondo.  Wax the heck out of it. And spray a coat of fiberglass with the chopper gun. 
That's your mold. Wax the heck out of the inside and make a part.  
Yes I glossed over a lot but it's not that hard. I could take just about any simple  body and make molds off it in a longish weekend. Pull parts the next weekend. 
if Fiberglass is too heavy, you can use cloth at a slight increase in cost and save about 1/2 the weight. 
Buy some expired prepeg  and do it in carbon fiber without vacuum bagging and autoclave and save 1/2 again the weight while getting stronger. 
How light?  Well race cars went to carbon fiber because aluminum was too heavy and not as strong.  Mind you the standard now is walk away from a 200+ mph crash. 
 

Money?  I'd be surprised if expired prepeg cost you much over $5-600 if you find the right source. If you want further details, just ask 

ps I have an XKE bonnet nose mold. 

In reply to frenchyd :

The unique rule for DM/EM is that the car needs to be recognizable as whatever you declare is as. I would have to declare it as something else and make it look recognizable from front and back. I know, I know, you have to squint to see MGB in my car but right now I have neither the desire nor the means to do a rebody. I'll be bringing both spoilers to Nationals and I have to look at the rules but I may be able to make the high downforce one adjustable with a height change, sort of like an adjustable Gurney flap

In reply to loosecannon :

Yeh changing a body to Jaguar  Spitefire or whatever  is not something you do at the snap of your fingers. More of a winter project.  But take a look at an XKE roadsters back end from the side.  Notice how it swoops up to meet the bumper?  Think there might be some additional down force there?

I don't have a the molds for the rear except the trunk lid. Doesn't mean a mold can't be made. Either from an actual car or a block of foam.  
You would need to  buy a set of taillights though.  

I see you used the super light non-vented rotor 2 piston wilwood setup.

How would you rate them? Would you consider them for street/autoX, on a 2500# car?

Allen says he feels a little fade if he is hard on the brakes at the drag strip with those brakes.

There is also the issue of wheel clearance.

Their next step up is vented and 4 pistons but a 14" minimum wheel size is recommended......

In reply to bentwrench :

There's no way the 2 piston calipers/rotors are big enough for a 2500 lb street car, in my opinion. My car weighs 1750 lbs with me in it and I've managed to overheat and warp my front rotors already.

And you are kind of stuck because you are using 13" wheels, no?

In reply to bentwrench :

I don't need much for brakes so I went with lightest possible. If I were going to do any track work, I would simply put ventilated discs on the front with some slightly bigger calipers, and probably keep my 13" wheels. Here's a picture from the last event

what rpm's and what gear are you in for the most part during a 'RUN'?

And how is this LHU holding up so far??? have you ever done DYNO pull on this?

In reply to 759NRNG (Forum Partidario) :

On our local course, I was only getting to 55 mph and 5000 rpm in 2nd gear. I run 2nd gear for most of the course but downshift to 1st for the pivots. The LHU has been great since I put the CBM road race oil pan on. I had it on the dyno a couple of years ago and it made 350 hp and 395 ft/lbs torque.

loosecannon said:

In reply to 759NRNG (Forum Partidario) :

On our local course, I was only getting to 55 mph and 5000 rpm in 2nd gear. I run 2nd gear for most of the course but downshift to 1st for the pivots. The LHU has been great since I put the CBM road race oil pan on. I had it on the dyno a couple of years ago and it made 350 hp and 395 ft/lbs torque.

and those numbers aren't really stressing it per se?? eh?

In reply to 759NRNG (Forum Partidario) :

No, those are pretty safe numbers for my stock parts. If I want to rev it higher than 7000 rpm, I need a better balancer but I've been told that the basic engine is good to about 500 hp at which point I need better rods. I have a high flow head and manifolds but am reluctant to install them because it changes the tune and the engine runs so good right now.

Having followed you for some time, I'm in full agreement on not making engine changes.  It's so solid now and it has all the HP you need to get the job done.  As you have mentioned before, getting the time behind the wheel will do the most good and keeping the setup consistent will go a long ways towards achieving your ultimate goal.  If the engine gave up for some reason, then it would be time to make the afore mentioned changes so long as you have the ability to de-tune as you have done with the current setup.  You are poised to really put the pressure on the top drivers this year assuming nationals are actual held.

loosecannon said:

In reply to 759NRNG (Forum Partidario) :

No, those are pretty safe numbers for my stock parts. If I want to rev it higher than 7000 rpm, I need a better balancer but I've been told that the basic engine is good to about 500 hp at which point I need better rods. I have a high flow head and manifolds but am reluctant to install them because it changes the tune and the engine runs so good right now.

I ask this because this bullet in my '73 B/GT makes way more sense than mazdafordoldsmobilebuick done before mash up......including Herr Tanner's LS bunker buster.....my take YMMV

A long time ago, I installed an aftermarket wastegate and 14 lb spring on the turbo in an attempt to get boost at a lower rpm. Since then, I have improved the tune by changing the variable cam timing, ignition timing and torque map and now I want the ability to have a low boost setting for low grip events (like rain) so I put a 7 lb spring in it. I also had some concerns about high temps around engine compartment and air cleaner so today I added some hood vents. I have two hoods so I can quickly switch from one to the other and see if there's any improvement in temps. Either way, I really dig the look of these vents. I made them myself and and quite proud of the results.

Probably a silly question, but do you have any forward facing air inlets to feed the outlet that those vents are?  It looks like great extraction, but with the whole grill and front looking like its blocked off...  I know you did that whole areo workup, seems a bit extreme if you are struggling with underhood temps is all. 

Car looks great, those vents look mean.