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Discussion Starter #1
So I ended up doing a very interesting rebuild on my 1.1 OHV cylinder head. This Kadett is a LeMons race car so everything has to be done on the cheap and that means getting creative. I found that Honda b16 vtec engine valves are nearly the same length as 1.1 Opel valves and are 1mm larger than stock as well. They also have 5.5mm stems so they are much lighter and flow more too. Right from the start the Honda valves are 10g lighter than the Opel valves and if one includes the keepers and retainers the difference is even greater. The Honda valves need to be shortened a bit and have their keeper grooves cut lower but with 1mm lash caps on there it all fits together and runs really well. Ended up using all the Honda stuff. Guides, springs, keepers, retainers, seals, and seats. Runs strong, zips up to 7k rpm with no complaints and doesn't burn any oil. Honda valve springs are stiffer too! I also made a custom manifold for a pair of 38mm motorcycle carbs that I had sitting about and now this thing is making a whole new level of power. Here are few pix of the setup.
 

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Now THAT gets my attention ! Finally someone has done it.
I picked up a 'spare' 1.1 head at Spannaway years ago, and have dreamed and joked about doing a 'Big' valve job.
The deepest I've been into this motor is an oil pan gasket on the bottom, and a valve adjustment on the top. 59,000 miles now.

Avendler, will you supply more details, part #s or year of donor, etc. Is this all standard machine shop work ? Thanks

p.s. Have you raced with Tinyvette ?
 

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Discussion Starter #3 (Edited)
The donor was a late 90's Del Sol but the b16 was available in a lot Hondas. Any decent auto machine shop should be able to do the work but they have to be willing to be creative. I used a little place called "Pioneer Machine" in Glendale Ca. and they really seemed to enjoy doing something weird. The only part of this that's not regular valve job work is shortening the valves and cutting new keeper grooves. That needs a lathe and not every automotive machine place can do that. Otherwise they have to bore the head for guides and seats then do a basic valve job. I had them do the seats and guides first, took the head back, hand ported it, then returned it for the final seat cuts. I also had them shave 1mm off the face of the head. The car now has 150psi of compression on each cylinder and that's on pistons and rings that are original from what I can tell. Valve spring pressure with the Honda dual springs is about double the stock Opel spec. I bet this thing would be ok to rev to over 7500 but the worn out stock bottom end would probably not love that feeling. For Lemons, I will set the redline and 6500 MAX.

I have yet to go head to head with TinyVette in the "Opile" but this fall we'll be running at Buttonwillow and probably see them there. We enjoyed the handling and light weight feel of the Kadett and hopefully a few more HP will make it even more fun. Just praying that we don't break anything because of our new peppy engine.

Here's a pic of the head with the guide "towers" machined off just before boring for guides. I replaced the thrust bearings on the exhaust side with steel spacers. It's amazing to me that the OE setup had NO guides or seats, just cast iron. Now with modern valve seals it burns ZERO oil. Also a work in progress pic of the intake for the 38mm motorcycle carbs.
 

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Thanks for response and info. Have you replaced all valves or intake only ? I imagine exhaust also with seats included as described.
.... That question already answered, Thank You
Did you run it with new valves and dual solex's to compare or were cycle carbs part of original plan ?
I would like to keep this one as visually original as possible so I'm curious if 'big' valves would have some benefit still using solex carbs.
Could springs of less pressure be used, if available, for less wear on cam and bearings. I'm not racing but a little more power would be nice.
And I would not rev 1,000 - 1,500 over redline in normal driving, well maybe in the heat of battle. Ha Ha

There was a 1.1 GT at Spannaway bored to a 1.2 , owner claimed some performance improvement. Parts may be unobtainium now.
IIRC there was an early Kadett at Rohnert Park in 2015 also made into a 1.2.

I've watched for any info on a 5 speed transmission that would be close to a bolt -in for 1.1 but have never seen it here.

I have been to LeMons / Tinyvette races at Sears Point, maybe I can visit Buttonwillow to support 2 Opels this year.
 

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The donor was a late 90's Del Sol but the b16 was available in a lot Hondas. Any decent auto machine shop should be able to do the work but they have to be willing to be creative. I used a little place called "Pioneer Machine" in Glendale Ca. and they really seemed to enjoy doing something weird. The only part of this that's not regular valve job work is shortening the valves and cutting new keeper grooves. That needs a lathe and not every automotive machine place can do that. Otherwise they have to bore the head for guides and seats then do a basic valve job. I had them do the seats and guides first, took the head back, hand ported it, then returned it for the final seat cuts. I also had them shave 1mm off the face of the head. The car now has 150psi of compression on each cylinder and that's on pistons and rings that are original from what I can tell. Valve spring pressure with the Honda dual springs is about double the stock Opel spec. I bet this thing would be ok to rev to over 7500 but the worn out stock bottom end would probably not love that feeling. For Lemons, I will set the redline and 6500 MAX.

I have yet to go head to head with TinyVette in the "Opile" but this fall we'll be running at Buttonwillow and probably see them there. We enjoyed the handling and light weight feel of the Kadett and hopefully a few more HP will make it even more fun. Just praying that we don't break anything because of our new peppy engine.

Here's a pic of the head with the guide "towers" machined off just before boring for guides. I replaced the thrust bearings on the exhaust side with steel spacers. It's amazing to me that the OE setup had NO guides or seats, just cast iron. Now with modern valve seals it burns ZERO oil. Also a work in progress pic of the intake for the 38mm motorcycle carbs.
Next stage ?:veryhappy https://images.app.goo.gl/QrP6RGfx6rW7s2EN7
https://images.app.goo.gl/MatnzCDPG139H77W7
 

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Thanks for response and info. Have you replaced all valves or intake only ? I imagine exhaust also with seats included as described.
.... That question already answered, Thank You
Did you run it with new valves and dual solex's to compare or were cycle carbs part of original plan ?
I would like to keep this one as visually original as possible so I'm curious if 'big' valves would have some benefit still using solex carbs.
Could springs of less pressure be used, if available, for less wear on cam and bearings. I'm not racing but a little more power would be nice.
And I would not rev 1,000 - 1,500 over redline in normal driving, well maybe in the heat of battle. Ha Ha

There was a 1.1 GT at Spannaway bored to a 1.2 , owner claimed some performance improvement. Parts may be unobtainium now.
IIRC there was an early Kadett at Rohnert Park in 2015 also made into a 1.2.

I've watched for any info on a 5 speed transmission that would be close to a bolt -in for 1.1 but have never seen it here.

I have been to LeMons / Tinyvette races at Sears Point, maybe I can visit Buttonwillow to support 2 Opels this year.
Big valves are always an improvement, but the intake ports should be cleaned up as they are quite restrictive in stock form.
The original springs are fine if in good condition and can be improved with shims to rev higher. There are stiffer aftermarket springs available too.
About boring a 1,1 to 1,2, that is impossible by boring alone, no way there is enough material for a 5mm overbore. But the original crank is forged and can be welded to increase the stroke. Or be off-center ground.
There is no 5-speed that fits without major fabrication, but Krause in Germany sells a conversion kit(unfortunately quite expensive).
Valves and valve springs https://www.krause-rennsporttechnik.de/shop/Motorenbereich/OHV/Zylinderkopf?languageid=2
5-speed conversion kit https://www.krause-rennsporttechnik.de/shop/Getriebe/OHV-4-Gang/OHV-5-Gang-Umbausatz-Kadett-C?source=2&refertype=1&referid=256&languageid=2
 

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Discussion Starter #7
Big valves are always an improvement, but the intake ports should be cleaned up as they are quite restrictive in stock form.
The original springs are fine if in good condition and can be improved with shims to rev higher. There are stiffer aftermarket springs available too.
About boring a 1,1 to 1,2, that is impossible by boring alone, no way there is enough material for a 5mm overbore. But the original crank is forged and can be welded to increase the stroke. Or be off-center ground.
There is no 5-speed that fits without major fabrication, but Krause in Germany sells a conversion kit(unfortunately quite expensive).
Valves and valve springs https://www.krause-rennsporttechnik.de/shop/Motorenbereich/OHV/Zylinderkopf?languageid=2
5-speed conversion kit https://www.krause-rennsporttechnik.de/shop/Getriebe/OHV-4-Gang/OHV-5-Gang-Umbausatz-Kadett-C?source=2&refertype=1&referid=256&languageid=2
You are correct from what I can see. The reason I went with the Honda valves is that they are available for under $20 each new and are much lighter. The smaller stems make more room for flow too. The best thing is being able to use modern valve seals so no more burning oil. I'm hoping to dyno the engine soon and give you all some real numbers to work with as to power. Just driving it I can tell it's a lot faster. I'm guessing around 80 hp.

Anyone have good info on how high these engines can rev and not blow up? Also, I'm eventually going to rebuild the bottom end. How much can these blocks be bored out?

Thanks!!
 

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The Honda valves sound like an excellent idea. 80hp sounds plausible with a ported head and the bike carbs. The crank has only three mains so it is important to balance the rotating assembly if driven at sustained high rpm's. The ohv tuners in Europe say that 80-90hp from a 11S or 12S engine is streetable, but when the power climbs over 100 naturally aspirated hp the lifespan of the engine decreases notably. The largest factory overbore is +1mm over std 75mm, but the block can probably be bored safely to 77mm.
A hot rodded ohv https://pdmclark.co.za/magic-of-1088/
 

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Discussion Starter #9
Did a bit of dyno time yesterday with some interesting results. The first run gave us 52hp at the wheels and that's not terrible for an engine with home brewed head work but a totally stock and pretty "broken in" bottom end with a stock cam. The bike carbs were a tad bit rich so after a bit of carb needle tuning that got cleaned up and it started making a bit more power. The biggest change was advancing the timing though. Using run of the mill California premium pump gas it never pinged and gained nearly 5hp from just the timing change alone. Even more significant was the big torque gains at lower RPM with the new advanced timing. It now is running around 40 deg BTDC of total timing. Seems like a lot but this setup really likes it.

After all the tuning we got a very repeatable 58hp at the wheels (maybe 70 at the crank?) and the car is running really well. So much more fun to drive now that there's a bit more low end torque and the peppy nature of the engine is a big plus. Here is a before and after pic of the first baseline run and the final result after tuning. Note low end torque gains. Also note that since this engine is in a 24 Hours of LeMons car the redline is electronically cut at 6200 RPM for longevity reasons. I'm betting there could be a few more HP available if we revved it higher but that's not what this engine is for!
 

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Discussion Starter #10
Thanks for response and info. Have you replaced all valves or intake only ? I imagine exhaust also with seats included as described.
.... That question already answered, Thank You
Did you run it with new valves and dual solex's to compare or were cycle carbs part of original plan ?
I would like to keep this one as visually original as possible so I'm curious if 'big' valves would have some benefit still using solex carbs.
Could springs of less pressure be used, if available, for less wear on cam and bearings. I'm not racing but a little more power would be nice.
And I would not rev 1,000 - 1,500 over redline in normal driving, well maybe in the heat of battle. Ha Ha

There was a 1.1 GT at Spannaway bored to a 1.2 , owner claimed some performance improvement. Parts may be unobtainium now.
IIRC there was an early Kadett at Rohnert Park in 2015 also made into a 1.2.

I've watched for any info on a 5 speed transmission that would be close to a bolt -in for 1.1 but have never seen it here.

I have been to LeMons / Tinyvette races at Sears Point, maybe I can visit Buttonwillow to support 2 Opels this year.
Just to answer this. I do think you would pick up a bit of power with the better valves and some porting even with the stock carbs. I also milled the head 1mm and that may be a part of the gains. The only reason I went with the bike carbs was that I had them (so free to me) and my engine was a single carb "S" not a dual carb "SR".
 

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Did a bit of dyno time yesterday with some interesting results. The first run gave us 52hp at the wheels and that's not terrible for an engine with home brewed head work but a totally stock and pretty "broken in" bottom end with a stock cam. The bike carbs were a tad bit rich so after a bit of carb needle tuning that got cleaned up and it started making a bit more power. The biggest change was advancing the timing though. Using run of the mill California premium pump gas it never pinged and gained nearly 5hp from just the timing change alone. Even more significant was the big torque gains at lower RPM with the new advanced timing. It now is running around 40 deg BTDC of total timing. Seems like a lot but this setup really likes it.

After all the tuning we got a very repeatable 58hp at the wheels (maybe 70 at the crank?) and the car is running really well. So much more fun to drive now that there's a bit more low end torque and the peppy nature of the engine is a big plus. Here is a before and after pic of the first baseline run and the final result after tuning. Note low end torque gains. Also note that since this engine is in a 24 Hours of LeMons car the redline is electronically cut at 6200 RPM for longevity reasons. I'm betting there could be a few more HP available if we revved it higher but that's not what this engine is for!

If it makes you feel any better, way back in the early 1970’s, Road & Track magazine dynoed a stock early (US spec) 1.9 Manta. It was rated at 78 SAE net hp at the flywheel. It made 47 hp at the rear wheels on a chassis dyno.

I think you’re doing just fine!

Nice job.
 

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Discussion Starter #12 (Edited)
Yeah. There's a lot of conjecture as to how much power get's lost due to driveline friction etc.. A data point I know for sure is that on the exact same Dyno I ran the Kadett on, a stock NA Miata 1.6 gives 99hp at the wheels and that motor is claimed to be 116 at the crank. But whatever the numbers are the car is running better than any 1.1 OHV I've even driven. Let's see how long it lasts on the track. Endurance racing, even LeMons, is really a test of a car.

Here's a pic of it strapped to the dyno. Note custom aluminum airbox with air Polaris buggy air filter inside and intake snorkle under cowl vents. Don't judge too hard, I just learned to weld aluminum.
 

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Discussion Starter #13 (Edited)
Well, tis the season for an update on the OPILE!

Since my last post we survived another 24 hours of Lemons race and had a pretty good time. Big issue was a massive oil leak out the front main seal that caused us to run the car with no oil pressure a few times. Somehow it didn't all fall apart, but it ruined the rod bearings by the end of the second day. Car did run the whole time and drive onto the trailer after the race. Win(ish)!

So it became time to build a new engine. We pulled the old lump and sure enough the rod bearings were seriously worn. Otherwise the engine was not too thrashed if you didn't mind several broken piston rings. I think they may have been broken for years, judging by the amount of carbon packed around the ring segments that were remaining. It's hard to believe the car ran as well as it did honestly.

I then searched high and low for an economical way to get new pistons at 77mm bore for a bit more displacement. The Vauxhall pistons that work are super rare now so it wasn't looking good at all to find a set cheaply. Here's when things took a very sharp turn for the better though. After heavy google use, I stumbled across the fact that 2002 Mini Cooper base model pistons and rods are dimensionally nearly identical to the Opel 1.1 pistons and rods. Except that they are wildly different in all the best ways. See pic. below. The Mini pistons and rods match in bore and nearly in big end diameter, while only being .005" longer from crank center to piston top than the Opel parts. Do you hear me? REVOLUTIONARY!

The Mini Cooper sticks and stones weigh nearly 5lbs less than the Opel ones and that's just the beginning of the benefit. Notice the longer rod length? That's a major bonus as well as now the engine has the same rod length to stroke ratio of a superbike or F1 car. True story.
 

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Discussion Starter #14
So to install these new and much better pistons and rods in my 1.1 engine I had to bore the block to 77mm and grind about .5mm off the rod journals on the crank. There is nothing fancy about what it takes to put these parts in a 1.1 and I used a neighborhood machine shop to do the work. Used Mini pistons and rods on ebay are very cheap and I bought new rings and bearings from "offshore" suppliers. Thing is, these pistons don't have valve relief notches in them so I was ready to cut my own until I checked the clearances and discovered that the valves were nowhere near hitting the pistons. As a matter of fact I ended up milling nearly 2mm off the stock "SR" head and still didn't need valve notches. CCing the head chambers after milling indicated I now have a respectable 9.7 to 1 compression ratio. The stock comp ratio is WAY less than the published numbers so pretty much any 1.1 should have the head cut just as a matter of routine. Here are some pix including one of the method used to check piston the valve clearance and of the parts that came out of my engine after the last race.:ugh: Also, a pic of me cutting a cubic buttload of weight off the stock flywheel on a lathe.
 

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Discussion Starter #15 (Edited)
After a relatively basic process of assembling the whole deal the engine is up and running and while I still am not totally done breaking it in, it is a completely different animal now. It revs up much faster and puts out a surprising amount of power. Much more than the 58hp at the wheels on the old setup and it's a bit of an effort to not hit the 7k rpm rev limiter all the damn time. Static compression test numbers went from 150psi per hole to 200psi, so that says a lot and I'm going to get the thing to a dyno and post some numbers as soon as break in is done so please stand by. Another interesting note is that the engine temp runs so much lower now that I thought the thermostat was stuck open because the temp wouldn't go above 180f. Even idling in LA traffic the electric fan almost never turns on now because it's set at 200f. Nearly 10lbs of rotating weight's been removed from the engine and yet it still has pretty decent street manners. I'll post a video of it running soon.

Honestly, unless something bad suddenly happens with this engine, I think nobody should ever put stock pistons and rods in a 1.1 ever again. The Mini Cooper parts are cheaper and so far looking like they have no down sides.
 

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After a relatively basic process of assembling the whole deal the engine is up and running and while I still am not totally done breaking it in, it is a completely different animal now. It revs up much faster and puts out a surprising amount of power. Much more than the 58hp at the wheels on the old setup and it's a bit of an effort to not hit the 7k rpm rev limiter all the damn time. Static compression test numbers went from 150psi per hole to 200psi, so that says a lot and I'm going to get the thing to a dyno and post some numbers as soon as break in is done so please stand by. Another interesting note is that the engine temp runs so much lower now that I thought the thermostat was stuck open because the temp wouldn't go above 180f. Even idling in LA traffic the electric fan almost never turns on now because it's set at 200f. Nearly 10lbs of rotating weight's been removed from the engine and yet it still has pretty decent street manners. I'll post a video of it running soon.

Honestly, unless something bad suddenly happens with this engine, I think nobody should ever put stock pistons and rods in a 1.1 ever again. The Mini Cooper parts are cheaper and so far looking like they have no down sides.
OK, because I know nothing about 1.1 engines (some people say I should just stop at the "nothing"), what is the new displacement?

Doug
 

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Really cool engine!!! Thanks for posting this project and I can't wait to see the dyno numbers.
 

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Awesome! Sure Sounds like a strong 1.1!
 
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