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1969 Opel Gt 1.9 Automatic
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The turbo came in today.

As expected, I had to re-clock the center section in order to orient the oil feed and drain lines correctly. When I re-clocked the compressor side of the turbo, surprisingly the wastegate actuator was pretty much just where it needed to be without binding. I may have to adjust the preload tension on the actuator, but it all JUST fits in there.

It did dawn on me that this setup won’t fit the early 1971-1973 engine mount brackets, only the 1974-1975 brackets. The waste gate actuator is nestled inside the engine mount practically!

Anyway, first impressions are that for $236 (delivered), this turbo doesn’t look too bad! I was expecting far more flawed castings and impeller wheels, but it didn’t look half bad. Time will tell however. View attachment 437054 View attachment 437055 View attachment 437056 View attachment 437057 View attachment 437058 View attachment 437059
Where did you buy the turbo from?

The engine looks very nice!

Also how much hp do you think it will make?
 

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In my my anticipation for the turbo yesterday, I failed to even notice another package had come in. In it, I got my twin 8” cooling fans for the Scirocco radiator, and the Pertronix ‘Flamethrower HV’ 60,000-volt coil with .45 ohm resistance.

I still need to fabricate a radiator shroud from aluminum (or fiberglass…haven’t decided yet), and I need to order the Pertronix 2 igniter.

Recurving a factory distributor is another step I’ll need to take as well. I already have all the other needed components for the ignition…Standard Ignition distributor cap, non-resistor ignition rotor, o-ring seal for the distributor base (in lieu of a gasket), and a ratcheting distributor hold-down handle and stud. I have a Magnecor wire set I was going to use but the coil wire doesn’t work with my new coil so I may go with a full custom 10 mm wire set instead.
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Where did you buy the turbo from?

The engine looks very nice!

Also how much hp do you think it will make?
I got the turbo off eBay, but it’s distributed by CX Racing.

How much power? Not as much as you might expect.

It depends on a lot of things. Your baseline HP, in other words how much power the stock engine is making, is one of them. A turbo isn’t a magic wand.

I chose a small turbo because the engine isn’t fully built. It has cast pistons. It uses stock fuel injection, which has limitations. I’m also running pump gas, not race gas.This turbo has a stock wastegate setting of 8 psi. I can raise the boost with an adjustable boost valve if I want to.

Based on the stock HP rating of 81 hp for a fuel injected 1975 Opel 1900, 8 psi of boost should give me around 125 hp
(Pressure ratio of 1.544 x 81 hp = 125 hp)

Now, if I modify the engine internally for better breathing, such as a slightly better camshaft and bigger valves, plus mild porting work, I should be able to increase the stock engine’s hp from 81 to about 95 hp. Multiply the pressure ratio of 1.544 x 95 hp, and now the same 8 psi of boost will yield around 146 hp.

Of course I did plumb in a water/methanol injection system so I don’t have to run race gas. Presumably I can also run higher boost levels. Let’s try again with 14.7 psi of boost (one atmospheric).

2:1 pressure ratio x 81 hp = 162 hp
2:1 pressure ratio x 95 hp = 190 hp

At that power level I would be very concerned with the stock pistons. The ring lands of the low compression pistons aren’t very strong. I’ve seen them break with 70 hp and bad ignition timing!

That said, I have a new set of standard bore low compression pistons laying around, which I might send out for ceramic coating. That would raise the danger threshold a bit. I just need to go thru my stash of engines and find a block with a good, stock bore with minimal wear and taper.
 

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I got the turbo off eBay, but it’s distributed by CX Racing.

How much power? Not as much as you might expect.

It depends on a lot of things. Your baseline HP, in other words how much power the stock engine is making, is one of them. A turbo isn’t a magic wand.

I chose a small turbo because the engine isn’t fully built. It has cast pistons. It uses stock fuel injection, which has limitations. I’m also running pump gas, not race gas.This turbo has a stock wastegate setting of 8 psi. I can raise the boost with an adjustable boost valve if I want to.

Based on the stock HP rating of 81 hp for a fuel injected 1975 Opel 1900, 8 psi of boost should give me around 125 hp
(Pressure ratio of 1.544 x 81 hp = 125 hp)

Now, if I modify the engine internally for better breathing, such as a slightly better camshaft and bigger valves, plus mild porting work, I should be able to increase the stock engine’s hp from 81 to about 95 hp. Multiply the pressure ratio of 1.544 x 95 hp, and now the same 8 psi of boost will yield around 146 hp.

Of course I did plumb in a water/methanol injection system so I don’t have to run race gas. Presumably I can also run higher boost levels. Let’s try again with 14.7 psi of boost (one atmospheric).

2:1 pressure ratio x 81 hp = 162 hp
2:1 pressure ratio x 95 hp = 190 hp

At that power level I would be very concerned with the stock pistons. The ring lands of the low compression pistons aren’t very strong. I’ve seen them break with 70 hp and bad ignition timing!

That said, I have a new set of standard bore low compression pistons laying around, which I might send out for ceramic coating. That would raise the danger threshold a bit. I just need to go thru my stash of engines and find a block with a good, stock bore with minimal wear and taper.
40-50hp is still a pretty good increase in hp.

Also just curious how much money would a better cam and valves be for a 1969 gt?
 

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40-50hp is still a pretty good increase in hp.

Also just curious how much money would a better cam and valves be for a 1969 gt?
It’s a massive increase, if you think of it in percentages. Going from 81 hp to 125 hp is a 55% increase in power. That would be like taking a modern engine with 300 hp and increasing it to 465 hp.

Camshafts depend on regrinds versus new billets, and solid lifters versus hydraulic lifters. It can cost $250-$400.

The same with big valves and porting work. You could put in Opel valves from a different head (such as 2.0 or 2.4 heads) which have the same stem diameters. This way you don’t necessarily need new guides, but you still need a machine shop to machine the seats oversized.

However the porting work is best left to a professional, especially on an Opel.

And if you decide to upgrade to a better flowing and lighter valve with smaller valve stems, then you need a whole bunch of extra machining for the supplemental parts such as guides, seals, springs, etc. That of course costs money. Better parts cost more too.

Figure $800 minimum for a reworked head with Opel valves, and $1400-$2200 for a head with everything replaced and machined, with high quality racing grade parts. The better the porting work, the more power potential there is, but the more it costs.

If you want to see a race-prepped 2.0 head, here is a thread from 2015 where I show the step-by-step process. That head cost $1850 at that time.
 

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40-50hp is still a pretty good increase in hp.

Also just curious how much money would a better cam and valves be for a 1969 gt?
Just to give you a visual on what bob is refering to.

Here's my 1.9L Head fitted with factory 2.4 L (45mm) intake valves and factory 2L ( 36 mm) exhaust valves.

The combustion chambers around the Intake valves have been unshrouded (opened up) to promote better air flow .
.

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Today was mostly a housework day. Didn’t get into the shop until later. Didn’t do much either!

I did however pick up some closed cell foam, as I decided to make the fan shroud from fiberglass. So I need a buck to make a mold from. I would’ve liked to have made the shroud at least twice as tall as I did to improve airflow thru the fans, but in an Ascona that just isn’t happening! There simply is no room. A Manta would have had the space though.
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I did however pick up some closed cell foam, as I decided to make the fan shroud from fiberglass. So I need a buck to make a mold from. I would’ve liked to have made the shroud at least twice as tall as I did to improve airflow thru the fans, but in an Ascona that just isn’t happening! There simply is no room. A Manta would have had the space though.
If you glue some stiffeners to the back of that you may be able to re-use the mold. Which means I would buy Unit 3 from you. I realize that Legere Motorsports probably doesn't want to get back into business by doing layups, but I'm just sayin'. Like most of the things you make, it's like "take my money".
 

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If you glue some stiffeners to the back of that you may be able to re-use the mold. Which means I would buy Unit 3 from you. I realize that Legere Motorsports probably doesn't want to get back into business by doing layups, but I'm just sayin'. Like most of the things you make, it's like "take my money".
The foam is the form or buck from which the mold will get made from. The foam gets tossed away.

While I will have a mold that I can then make multiple parts from, I’m doubtful there will be too many people who will be using a Jeg’s Scirocco radiator with twin 8” Speedway cooling fans in their Opel.
 

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Been a busy week. Mostly house work, but I managed to take 4 days off too, and attended the Mt Washington Hillclimb. Amazing weather and an amazing event!

Anyway, during my absence a few things I ordered came in. Mostly related to the turbo. As usual, when you buy something cheap you get what you pay for. In this case, I’m finding that the turbo has some non-standard features. Tracking things down has been interesting. And in one instance, I had no choice but to make it myself! All in all, I will probably have as much invested into the turbo plumbing (oil and water, and gaskets/flanges) as I do into the turbo itself.


First things first. While the oil drain bolt pattern is correct, it is in no way centered over the turbo oil drain hole! If I used a standard T25/T28 drain tube it would partially block the oil discharge on the turbo. Never good.
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The solution, of course, was to make a custom turbo oil drain flange. I cut it out of 3/16” steel, and brazed a 5/8” steel tube to it.
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I used my tubing beader to produce a raised bead on the metal tube for better hose retention. I’ll probably have it zinc plated.
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Note that I had to put a bend and a slight offset in the drain tube in order to clear the wastegate actuator rod
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Here you can see a 3/8” banjo tube fitting which is the feed for the water-cooled center section. It gets REALLY tight in here, so much that I had to order a small-head banjo bolt (M14 x 1.5 pitch) to clear the turbo mounting flange stud. Even still, I will be using a shortened mounting stud and a small-head (10 mm) copper exhaust nut for clearance.
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Close-up at the banjo bolt. Very tight fit.
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The black fitting in the center of the turbo is the discharge line for the water cooled center. It’s also M14 x 1.5 pitch.

At the top of the pic, there is the oil feed line, which is an oddball size. Usually a turbo will have an 1/8” NPT feed. Sometimes an M11 x 1.25. Sometimes M12 x 1.00. Sometimes M12 x 1.5. This turbo however, was M12 x 1.25. Weird. Hard to find and expensive banjo bolt too. The oil feed line will be a -4 AN (1/4”) copper-nickel tube with 37 degree tube nuts for attachment.
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Then there is the turbo discharge flange. I tried a GT25/GT28 flange I had. Nope. I ordered a T25/T25 flange then. Nope. So then after some research I found out it matches a Nissan T25/T28 flange, even though this turbo is universal and not vehicle-specific. Not rare, but not exactly common everywhere either. So I now have one of those in order now, along with a gasket.

I also picked up a manual boost controller if I want to increase boost above the 8 psi baseline setting that the supplied wastegate gives. Nothing crazy, but a ball-and-spring regulator is arguably better than an air pressure regulator valve.
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The form for the radiator shroud got finish sanded today, and I applied a cost of epoxy to it to seal it. It will probably need another coat and then some minor bodywork to fill voids and dips, and probably a couple more coats of epoxy over that. Then it will get wet sanded and buffed until shiny and smooth. From there I will make the mold for the finished part.
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The new T25/T28 turbo discharge flange showed up today. And it’s wrong. So, thats 3 different, yet still incorrect…discharge flanges I’ve tried. It’s getting expensive now just buying things that don’t fit, so no more guesswork for me. I’ll just make one from scratch when I have the time.

For the record I tried a T25/T28 Garrett flange, T25/T28 Nissan flange, and GT25/GT28 Garrett flange. Ugh. Again, more crap that wastes time and money trying to save money buying a ‘cheap’ turbo. Not really worth it.
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On a happier note, I came up with a merge connector for my coolant surge tank feed lines. My surge tank has two 3/8” feed fittings and a single 5/8” return fitting.

I will have one 3/8” line coming from the top of the thermostat housing (highest coolant point on the engine), and that will merge into another line on the top of the radiator, which will then go to the surge tank 3/8” fitting near the rear firewall (higher than both ports on the engine and radiator). This purges any potential air pockets from both the engine and the radiator.

There will be a return coolant line from the turbo which goes to the other 3/8” fitting on the surge tank. The 5/8” line on the surge tank is the ‘return’, and it will get plumbed into the lower radiator hose, which siphons into the engine via the water pump. Normally I would ‘T’ into the heater hose return line on top of the water pump, but in this instance, there’s a lot going on at the front of the engine from the EFI and turbo, and therefore not much space!

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Welded up the merge collector for the coolant
lines.
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I also dug out an old flywheel for the turbo engine.

I think this was the first flywheel I modified for an S-10 clutch, back in 1992 or so. It’s been behind a few engines over the years, but never abused. I’ll magnaflux it at my machinist’s, then I’ll bead blast it, and I’ll have him re-surface the face. I was just going to install a stock replacement organic clutch setup, which is about $80 for the complete kit.

That would be MORE than capable of handling 200+ hp and 250 + ft lbs, so it’s more than enough for this project, and very driveable.

I tossed it on my UPS scale and got 15.75 lbs, which is around 7 - 7.25 lbs lighter than stock. The S-10 9.125” presssure plate is also about 2 lbs lighter than the stock Opel 8” pressure plate. So roughly 9 lbs less rotating mass than OEM.

Add in a 3.90 rear axle and 150+ hp and it should move out nicely.
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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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Well compared to RallyBob I would have to say that my afternoon in the garage was not nearly as interesting or impressive, but it was productive. I did however take care of a couple of issues - dropped the steering column, I swear for the last time, pulled the steering wheel, replaced the hub and realigned the steering wheel correctly so that when the car is driving in a straight line the tach and speedometer are in full view - I had screwed that up sometime in the past. Was able to install the screw holder, thing behind the right side of the instrument panel so that I can actually tighten the panel on the right side as well as the left side. That reminds me of someone posting a question on the number of screws holding the instrument panel in place, I answered two as my 70 GT does in fact have only 2 visible screws holding the unit in place. I recently saw a picture of, I assume, a newer model and it appeared to have five holes in the instrument panel to hold it in place. The way the 69-70 modles were designed it appears to remove the instrument panel that the whole dash would have to come out as there are a number of tabs that lead me to believe that the instrument panel was attached to the dash in several areas not accessible unless the dash was also removed. Needless to say I never used those additional connections and I would bet in 1971 the 5 holes resolved that early design flaw - I am guessing here... I also installed the new seat belt and tightened down the carb. Due to the fact that everything that I did today was a redo it was kind of fun to know exactly what I was doing and it all went pretty fast which is not the usual scenario. I am waiting for a gallon of Lube to be delivered for the transmission so the car has been drained and is still on jack stands waiting for that delivery.
 

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Plans changed ever-so-slightly. Numerous tolerance stacks dictated that an improvement could be had by spacing out the turbocharger 1/4” from the exhaust manifold. I stacked washers to test my theory and it looks like it will make a lot of things easier. I will however need to order a 1/4” thick mounting flange as a spacer (yes, they exist, I checked first!).

How does this help? Well, first of all it allows me to clock the compressor housing on the turbo so that the discharge points down. This makes the intercooler plumbing MUCH easier. Secondly, it gives more room to access the mounting nuts that secure the turbo to the manifold. Third, it gives improved access to the oil feed line at the top of the turbo. Fourth, it opens up the air gap between the turbo and the intake manifold. This leaves me with more room for a heat shield, and should reduce heat transfer a little bit. The only negative seems to be that the wastegate actuator gets closer to the engine mount bracket. I will grind a little bit off the bracket to improve clearance.
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The wastegate actuator arm sits about 1/16” away from the engine mount bracket currently.
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Clearance between the intake manifold and the turbo has improved.
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The intercooler hoses can be run essentially side by side now.
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The turbo oil drain routing. I need to weld the steel tube to the oil pan, but otherwise it’s all figured out.
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No work in my shop today.

I did, however, receive my fuel injectors today. I wanted to change injectors for a multitude of reasons. I need higher fuel flow of course. I also wanted a more modern double o-ring design so I could use a higher volume fuel rail. A more modern spray pattern doesn’t hurt either!

Now, since I’m retaining the factory 1.9 L-Jetronic ECU, there are limitations. First, I needed the injectors to be low impedance. Second, since the ECU is analog and not tunable at all, I really only wanted the injectors to flow about as much as the expected airflow increase from using the 2.0 liter AFM. I really can’t tune it, I can only adjust fuel pressure, idle air bypass, and AFM air flap tension.

The stock 1.9 injectors are roughly 19 lbs/hr fuel flow. The 2.0 air flow meter is about 44% larger in area. I settled on a 26 lb/hr injector which is about 37% more fuel flow than stock. A small increase in fuel pressure can get me to where I need to be.

I have a high pressure fuel pump I’ll be using (up to 9 bar/132 psi), and a rising-rate adjustable fuel pressure regulator. I can set baseline fuel pressure, and pressure under load. I can increase fuel pressure as much as 14 psi per 1 psi of positive boost, or as little as 1 psi of fuel increase per 1 psi of boost.

Hopefully it will all work out, but it will certainly take some doing.

I ended up buying a set of rebuilt and flow-balanced (used) Rochester 26 lb injectors with 2.5 ohms of resistance, which use the same plug as the OEM Opel Bosch injectors. Only about $85 per set delivered. 6-hole nozzles should have a better spray pattern too.
These fit right into the aftermarket 14 mm injector bungs I’ll be using. The tops will be connected to a piece of 3/8” extruded aluminum fuel rail.

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I ground down that pesky engine mount bracket today. Tons of clearance to the wastegate actuator arm now
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I also silicon-bronze welded the turbo oil drain tube to the oil pan.
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