These are such cool looking cars. Thanks for sharing.
These are such cool looking cars. Thanks for sharing.
glad to see the Opels are back
Glad to see this thread back on page 1. I love the Opile
Turbine said:Glad to see this thread back on page 1. I love the Opile
Agree 100%.
AngryCorvair (Forum Supporter) said:Turbine said:Glad to see this thread back on page 1. I love the Opile
Agree 100%.
Same!
I like Opels.
Awesome, thanks everyone.
I've already got a decent list of improvements I'd like to make to the Opile. I'm not sure if all of them will happen but by driving the car around on the street for a few months I really got to know its quirks and had plenty of time to think about what I'd like to do it.
For the sake of documenting my thoughts, here's the list of smaller bite-size tasks:
And the big ones:
It's been a while since any engine bay photos were posted. Here's the current state of affairs:
Alex had it looking really nice with the grey paint, but then something happened relating to brake fluid (I've been there). I'm thinking of scuffing and repainting the whole bay again including the cowl area. Then ebarking on the wiring tidy-up.
Bonus quiz: who can spot the Volvo 240 part in the engine bay? There's only one (so far). We try to include a few in every Black Iron Racing car.
A couple of weeks ago I took the Opile back to our shop to live indoors for a while, and couldn't resist getting shots of all three Kadetts lined up as if our parking area was some kind of apocalyptic Opel dealership lot.
I just re-read your whole last race write-up. It was just as good of a read as the first time around! This little car is the David we all love to root for: modified in all the right ways, purpose built but still crude, humble and effective. It's the perfect blend.
In reply to Mezzanine :
Hey, thanks! It's fun putting those write-ups together. They also come in very useful later on (such as now, over a year since then) helping us remember what our strengths and weaknesses were, and where our heads were at. Glad to see others enjoy them as well. Someday I'd really love to make a cohesive race video to tell more of the story. Alex is a cinematographer and now that he isn't the Opile's main handler, maybe we can convince him to document the next one.
Cheers & Happy New Year
-Chris (Duder)
Next chapter - coming soon!
(I mean engine stuff; I have not bought a wagon)
I realized a while ago that the "Brazilian" 1.1L pushrod engine was only partially documented here, or should say I felt like we needed to document it better. Neither me nor Alex ever planned on going into business building these so we might as well share what we've learned with the car kook community at large. I was present during the original build but was more adjacent to the work than elbows deep in it, so I figured, what's the best way to really learn & record what goes into one of these? Build another one - or two!
So let's see if I can contribute to the Opel hot rodding world a bit more by detailing one way to make this "husky" little powerplant even more lively.
Building a Brazilian - Pushrod Opel with Mini Tritec Pistons & Rods
As a recap, the basic formula for the Brazilian is to get some pistons & rods from an R50 / R52 Mini Cooper, the naturally aspriated non-S, then stuff them into the Opel block and make the Opel 1.1L crank play along. The savings in reciprocating mass is around 2 lb (= 900g) vs. the original Opel pistons & rods. The Mini parts also offer longer rods, shorter skirts, increased compression height, modern rings, modern materials & quality control, and flat tops. The parts I'm using came from ebay, and they are "pre owned." I haven't seen any broken or failed parts so I'm not sure what to watch out for when buying them, other than careful visual inspection for damage. The wrist pins are a very tight interference fit in the rods, so removal and installation of them probably requires help from professionals. Incidentally we call this the Brazilian because the 1st-gen new Mini's engine, known as the Tritec, was built in Brazil... after being co-designed by Rover and Chrysler, go figure.
Here's what you'll end up with, including specs for the slight overbore required on the block. Here in the US our Kadett Bs came with the 1.1L (1078cc) with a 75.00mm bore. The overbore to 77.00mm is for standard-size Mini pistons, and gives 1136cc. Otherwise known as 69.3 CID. Nice.
Disregarding the valvetrain and the rest of the engine for a minute, we know we can safely rev the Mini pistons & rods well past the rotational speeds they would've seen in the 1.6L Mini Tritec engine. The naturally aspirated 1.6 was called the W10 from what I've found. That engine was very undersquare, with a stroke of 85.8mm to go with the 77.00mm bore. Those same pistons and rods have much less distance to travel in the same amount of time when we attach them to the Opel crank with its short n' sporty 61.00mm stroke. Looking at linear mean piston speeds in ft/s I concluded that we could easily rev these suckers to almost 10,000 rpm in the Opel Brazilian. That's not to say the crank wouldn't break and the valves wouldn't float and the bearings wouldn't spin far below that figure, and we don't know the Chryser/Rover engineers' actual mean piston speed limit for these parts, but at least we do know there's a healthy 19% safety margin if we rev the Opel to 8,000 rpm, for example. The Mini's rev limiter is set at 7,000 rpm so we can use 65.7 ft/sec as our mean piston speed limit.
After getting your hands on some sweet Tritec pistons & rods, the next step is to take your Opel 1.1L pushrod block and crank to a machine shop and have them bore out the cylinders and grind down the rod journals per my notes below. It's also a good idea to get some new stock Opel main bearings and check your main clearances before machining, or have the mains ground undersize if you find damage when you tear down your Opel lump.
I had some bad info on the handwritten page above ^ so I redacted that and typed the right stuff in for posterity ;-)
So here's the block I started with for my TurbOpile build. This bottom end will be built for boost in terms of ring gaps, but everything else is basically identical to what Alex did for the original NA Brazilian in the Opile Lemons car.
This was a mystery shortblock we got with the red cars, and from the 1975 date codes and odd serial number I think it was a factory built replacement engine. There was basically no wear on any components, just a healthy coating of shelf rot from sitting for so long unused in Phoenix. It wasn't wise to run it as-is because of all the dirt and surface rust in the cylinders, so it became Brazilian No. 2.
The three bottles of Pacifico total 1064cc in liquid volume (yum). The stock Opel displacement is 1078cc. Pretty damn close.
Here we are with the crank and cam and the bottom of the block. There was junk on all of the journals that was probably petrified assembly lube, but it all came clean. You can see how very much of a 3 main bearing engine this thing is. Like, it's so blissfully unaware that there are any engines out there in the world with an exorbitant count of 5 mains.
Main caps on these engines are funny - the front one actually sits partially out in the fresh air, outside of the oil pan.
Back together with plastigage to check main clearance:
Nominal clearance is 0.033mm, with an acceptable range of 0.010mm - 0.056mm according to Ferdinand Opel. Everything checked out OK so off it goes to our friendly Glendale machinist, Art at Pioneer Machine.
I had a giant novelty ziploc bag and this is a tiny novelty engine block so naturally I brought them together.
A few days later I got a call from Art and picked up the block and crank, along with the mains and one piston which they used to ensure everything was kosher.
This block is quite pretty when it's all cleaned up. Really a nice piece of casting design. It's a shame it's normally hidden at the bottom of a Kadett engine bay with an ugly head and some boring parts bolted to it!
The freshly ground & polished crank looks better in black & white 
The corner radius between the rod journal and webs needs to be small enough to clear the chamfer on the Mini rod bearings, which was another reason the machinist wanted a piston & rod, and I'm glad they thought about that because it's something I probably would've missed until it was too late.
After a lick of paint she's looking quite fetching. I believe Opel painted these gray from the factory, and the closest I could find was "Ford Gray" as an available VHT color. I think it works.
I moved on to filing rings to get my gaps opened up for mild boost. A bit on the large side but nothing excessive. I ended up with 0.015 - 0.016 inch gaps for the 1st rings and 0.018 - 0.020 inch for the 2nd rings. Bonus GRM sticker in the background...
Piston crowns do end up above the deck at TDC, and I measured between 0.021 to 0.026 inch stick-out which will need to be accounted for with the head gasket and head machining. Lucky that these were such low compression engines to begin with, there's plenty of meat on the head to make everything work even with some generous surfacing. Incidentally, my block has not been decked.
I bead blasted the main caps and got the bottom end buttoned up. The rods do have a bit of side clearance as installed, meaning axial movement along the direction of the crank centerline. I measured between 0.029 to 0.031 inch for this, with the stock Opel max spec at 0.010 inch. Sounds scary maybe, except the Opile race car has been running exactly like this for a few years with no ill effects.
This is as far as this Shorty McShortblock goes for now. It will get oil squirters before final assembly.
Signing off,
Chris / CFlo / Duder
Can you check a few things from the Mini pistons and rods
Pin size
center of pin to top of piston ,
Big end size
center of big end to top of piston
You probably already have those sizes to check the Opel block fit .
Thanks
Great write up, thanks for sharing
californiamilleghia said:Can you check a few things from the Mini pistons and rods
Pin size
center of pin to top of piston ,
Big end size
center of big end to top of piston
You probably already have those sizes to check the Opel block fit .
Thanks
I don't have any of those dimensions documented, but could take measurements. Are you looking to fit these into a different block?
In reply to Duder :
Yeah , just might be a source for some 77mm pistons and rods
But if its already together don't take it apart to measure it , it not that important .....
and we can figure it out later.......
In reply to californiamilleghia :
No worries - I have a spare. I'll measure it and post up my findings.
"All right all right all right," here we go...
Let me know if you need other measurements!
Drawing below is not to scale.
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