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Opel Kadett C
Power hp
Torque Nm
Displacement L
Layout
Swap overview with verified parts, part numbers and sources.
C20XE in Opel Kadett C.
Documented from 38 recorded sources: 5 of the ten mandatory blocks are carried by two independent publishers, 3 remain open, 1 does not apply. Internal confidence 68%.
C20XE: 1,998 cc (1,984 cc by the German tax formula), four cylinders in line, DOHC 16 valves, naturally aspirated, 110 kW/150 PS at 6,000 rpm. Torque is given as 196 Nm, at 4,800 rpm up to model year 1992 and at 4,600 rpm from model year 1993. A version without a regulated catalyst is quoted at 115 kW/156 PS and 203 Nm. Engine management is Bosch Motronic M2.5 with distributor ignition up to model year 1992 and Motronic M2.8 with distributorless ignition from model year 1993; the engine has cylinder-selective knock control and may therefore be run on 91 RON regular petrol as well as 95 RON. C20LET: same displacement, turbocharged, 150 kW/204 PS at 5,600 rpm, 280 Nm at 2,400 rpm, Bosch Motronic 2.7, factory-fitted with the F28 six-speed gearbox and four-wheel drive, 0-100 km/h in 6.8 s and 245 km/h in the donor car.
Status: VERIFIED · Confidence 84%
Both. The C20XE is naturally aspirated - 110 kW/150 PS at 6,000 rpm from 1,998 cc - and this is the variant that every Kadett C source found in this run actually describes. The C20LET is turbocharged at 150 kW/204 PS at 5,600 rpm with 280 Nm already
For the C20XE the data sheets name four donor models with their build periods: Kadett E 1988-1991, Vectra A 1989-1994, Calibra 1990-1993 and Astra F 1991-1996. The choice among them is a Motronic choice - up to model year 1992 M2.5 with a distributor, from model year 1993 M2.8 without - and a cylinder head choice. For the C20LET the only donor is the Calibra Turbo, built 04/1992 to 07/1996; one Kadett C builder solved the sourcing question by buying a complete Calibra with a freshly rebuilt engine rather than a loose unit. What has to come across from the donor, by the one detailed installation guide found, is: control unit, engine wiring harness, covers, coolant expansion tank, coolant lines, flywheel, ignition coil, distributor, and exhaust system including catalyst. What has to come from the Opel rear-wheel-drive parts bin instead is the whole drivetrain interface: an oil pan from the 1.8 Manta, a bellhousing from a 1.8-litre four-speed OHC Manta B or Rekord E 1.8S, and a rear-wheel-drive gearbox. Head castings are worth choosing deliberately: CosCast heads are described as thicker-walled than the KS/Kolbenschmidt heads and are the preferred option in the classic scene.
From the donor car, complete: engine with control unit, engine wiring harness, covers, coolant expansion tank and lines, flywheel, ignition coil, distributor (M2.5 cars) and the exhaust system including catalyst. Prefer a CosCast cylinder head; prefer a model year 1993 or later car with Motronic M2.8 if the distributor packaging is a concern. From the Opel rear-wheel-drive parts bin, and this is the part the donor cannot supply: the oil pan of the 1.8 Manta, preferably the aluminium one, with a solution for the pickup pipe; a bellhousing from a 1.8-litre four-speed OHC Manta B or a Rekord E 1.8S; a rear-wheel-drive gearbox (see the gearbox field, where the sources disagree); and a propshaft, either shortened or purpose-made depending on gearbox. Buy new: the engine mount bracket set at 182.65 EUR and, if the donor brakes are to be used, the caliper adapter at 195.08 EUR, both prices as of 25 July 2026. Expect to fabricate or have fabricated: exhaust manifold and system to the centre silencer, and an enlarged propshaft tunnel. Reinforce the rear axle shaft only from about 180 PS upwards.
Status: SUPPORTED · Confidence 74%
Two documented routes, and they are a generational difference rather than a contradiction. The older forum answer is to make the brackets yourself: for the Kadett C "Die Motorhalter muss man sich selbst anfertigen", and in the related Ascona A and Manta A the advice is to take the 1.8S brackets as a starting point and fabricate from there. The newer answer is a bought part: a German maker sells a bracket set (article 535) explicitly for "Opel 16V oder 8V Motor in deinem Manta B, Ascona B oder Kadett C" at 182.65 EUR, price as of 25 July 2026, bolted with M12x30 in grade 10.9 or 8.8 and supplied with slotted holes so the engine position can be set. The same maker supplies the rubber mounts in a standard size of 70 mm diameter and 50 mm height, with motorsport heights from 30 to 70 mm to set a different inclination. The chassis-side constraint is stated plainly and is the single most useful sentence found on the subject: the Kadett C front axle offers three holes per mount seat, and "Ein Ansetzen der Motorboecke an Loch 1+2 ist nicht moeglich ohne die Feuer-/Spritzwand zu bearbeiten" - i.e. the two forward positions buy space at the front only at the price of bulkhead work.
This is the clearest answer in the whole dataset and it comes with its reason. The engine keeps neither its own sump nor its own pickup: it takes the oil pan of the 1.8-litre Manta, and the reason given is exactly the classic collision point this block asks about - that pan "den Oelsumpf hinten hat und vorne im Lenkgetriebebereich schoen flach ist", i.e. the sump sits at the rear and the front is shallow where the Kadett C steering box is. An aluminium 1.8 Manta pan is the preferred version. Two independent publishers name the same part for the Kadett C and for the related longitudinal Opels. Two practical catches are documented. First the fastening: the older pan uses M8 bolts where the later engine's own pan uses M6, with the pragmatic answer "bohr die loecher auf und gut ist". Second, and much more serious, the pickup: the later oil pump does not match the Manta pickup pipe, and one builder reports "Es ist quasi unmoeglich das Oelsaugrohr da durch zu fuehren". Documented ways round it are a fabricated flange welded to the pickup pipe by a specialist, or a custom-made pan; one builder concluded as late as 2024 that with the 1.8 pan it works "gerade so".
DISPUTED: the sources disagree on which gearbox belongs behind this engine, and the disagreement is not cosmetic. Position one, from a Kadett C thread: "Zum C20XE Motor im Kadett C passt am Besten ein Omega A 2.0i Getriebe. (wg. Heckantrieb)", with Getrag 240 ("nicht 265!") and ZF units named as the ones that "passen ohne Probleme in ein Auto mit kleinem Tunnel". Position two, from a second Kadett C thread: the 265 is "das beste Getriebe fuer diesen Motor", and the propshaft is already there for that variant. Position three, on the Omega gearbox, contradicts position one twice over - within the same first thread it is also called "nicht besonders haltbar" with a "sehr kostspielig" propshaft conversion, and in the Ascona A and Manta A scene the verdict is "Lass die Finger von den Sch*** Omega Getrieben, gibt nur Aerger". All of these are tier 5 forum statements; no manufacturer document, no installation instruction and no technical drawing was found on this question, which is itself the finding. What can be said without contradiction: the only factory gearbox that bolts to a C20XE or C20LET in unmodified form is "das 240er Getrag des Rekord/Manta 1,8S", and it is rated for 162 to 185 Nm against the engine's 196 Nm - one Kadett C source puts it plainly, "Das 240er Getrag ist meiner Meinung (mittlerweile) nach mit dem C20XE bzw. 150PS schon etwas ueberfordert". The 265 is rated to 310 Nm. ZF units "halten aber mehr aus als die kleinen Getrag Getriebe" at the price of straight-cut noise and a notchy shift. A Ford Type 9 is named as a further option with an adapter plate and aluminium bellhousing. The bellhousing for the Getrag route comes from a 1.8-litre four-speed OHC Manta B or a Rekord E 1.8S, with an adapter plate between gearbox and bellhousing on the four-speed route.
No reliable combination-specific information found on gearbox mount and transmission crossmember in this combination.
Status: OPEN
No reliable combination-specific information found on shifter, lever position and tunnel opening in this combination.
Status: OPEN
Two Kadett C publishers, and they agree: the clutch comes off the donor engine, and only the friction plate is chosen to suit the gearbox. "Die Schwungscheibe und Druckplatte passen vom XE/LET" - flywheel and pressure plate carry over. The friction plate is the adapting part, and it is gearbox-specific. Behind a Getrag 265 one builder used a plate from the Senator or Monza. Behind a 240 OHC Getrag "passt die komplette Turbokupplung inkl. Mitnehmer" - i.e. the complete C20LET clutch including the plate. A second Kadett C thread describes the same principle from the naturally aspirated side: the factory dished flywheel with the pressure plate, and a friction plate from the C20LET. One further gearbox-dependent part is documented: the Omega gearbox route requires an extended release bearing.
Status: VERIFIED · Confidence 82%
No combination-specific automatic transmission solution documented.
Status: NOT_APPLICABLE
No combination-specific automatic transmission solution documented.
Status: NOT_APPLICABLE
No combination-specific automatic transmission solution documented.
Status: NOT_APPLICABLE
No combination-specific automatic transmission solution documented.
Status: NOT_APPLICABLE
No combination-specific automatic transmission solution documented.
Status: NOT_APPLICABLE
Which propshaft is needed follows directly from the gearbox choice, and that is precisely why the sources differ here too. On the Getrag 265 route one Kadett C source states the propshaft is already there. On the Getrag 240 route the Kadett C shaft from a ZF five-speed car or from a 1.6S automatic is named as the basis. On the Omega gearbox route a modified shaft is required and is described as the expensive part of that option. Independently of gearbox, one Kadett C thread states that the shaft has to be shortened and that a reinforced shaft is wanted, and in the related Ascona A and Manta A the conclusion is that the original shafts do not fit exactly and one has to be made up. The body work that goes with it is stated without disagreement: "der Kardantunnel aufgeschnitten und vergroessert werden muss". Nothing was found on lengths, tube diameters, centre bearing or balancing.
The Kadett C keeps its own live rear axle, and it is a known quantity in the Opel scene. The larger CIH axles of the Manta B, the Kadett C and the Manta A are described as interchangeable among themselves, with two mechanical caveats: the Manta B axle is about 2 cm wider per side and the Kadett C axle about 8 mm narrower per side, and the mountings for the anti-roll bar and the handbrake cable are not compatible. Documented final drives in this family are 3.18 (the longest, from the Manta A GT/E), 3.44, 3.67, 3.70, 4.11, 4.22 and 5.28, with the rule that a larger number means shorter gearing and lower top speed; a 40 % limited-slip unit is mentioned for the Manta B axle. One Kadett C C20LET project runs the 3.18 axle. On durability the picture is specific: the estate axle is stated to be the same as the saloon axle, a reinforced axle tube shaft is described as worthwhile only from about 180 PS upwards, the aluminium neck and the axle extension are named as the parts that fail, and one builder reports replacing the original 18 mm solid shaft with a 24 mm hollow one plus a stiffer centre bearing. With careful use the axle is credited with over 200,000 km even at 180 to 200 PS.
Status: VERIFIED · Confidence 82%
Transferred from related longitudinal rear-drive Opels of the same era, because nothing reliable was found on the Kadett C itself. The starting point is the problem: the recipient car is a carburettor car with a low-pressure system, the engine needs a pressurised injection supply with a return line. From the engine side, the required pressure is documented at 2.3 to 2.7 bar without vacuum and 2.0 to 2.2 bar with vacuum for the Kadett E C20XE, rising to as much as 3.5 bar on Motronic M2.8 cars from model year 1993. From the practice of converting an Ascona A or Manta A tank - the same era, the same layout - the recorded solution is to cut an opening of about 19 cm diameter in the top of the tank, weld a swirl pot to the tank floor, feed it with a 12 mm steel suction pipe and return into the same swirl pot rather than into the tank at large; one builder records as his own mistake that he converted an existing breather pipe into the return line instead of adding a separate one. Pump positions used on comparable Opels are under the floor at the rear seat well, on the crossmember, or under the boot floor as on the Manta B. Line routing on the factory GT/E runs along the passenger side through the jacking point and the right-hand wheel arch.
Status: TRANSFERRED · Confidence 45%
Transferred from related conversions, because nothing reliable was found on the Kadett C itself. Two engine-side points recur. First the expansion tank: the C20XE tank has three connections, and the documented answer in a comparable conversion is to use a tank from a model without ABS. Second the fan: the recommendation is to replace the plastic-rimmed factory fan with an aluminium-rimmed one for heat resistance. From the longitudinal Opel scene the additions are a high-capacity radiator with a thermal switch, an electric fan, and keeping the engine's own oil cooler, which is described there as mandatory rather than optional. Nothing was found on which radiator physically fits the Kadett C nose, on hose routing, or on whether the factory Kadett C radiator has the capacity for 150 PS.
No reliable combination-specific information found on intercooler and charge piping in this combination.
The manifold is the problem, not the pipework behind it. For the Kadett C the recorded requirement is blunt: "der Faecher muss umgeschweisst werden", and manifold plus system have to be re-welded as far as the centre silencer. In the related Ascona A and Manta A the same job is described either as a rebuild of the original manifold or by fitting an aftermarket item. A German supplier lists a racing system with a 4-2-1 manifold specifically for the Kadett C under article APT002, price on request only - but the listing does not say which engine it is cut for, so it is evidence that a Kadett C racing system exists, not that it fits this engine. From the turbo side, one Kadett C project inherited a Remus system with a German ABE together with the donor Calibra, which is the only exhaust part found in this run that carries any type approval at all. Nothing was found on catalyst position, on silencer position, or on how the system clears the enlarged propshaft tunnel.
The decisive question is which Motronic the donor carries, and for this recipient car it is a packaging question rather than a tuning one. Up to model year 1992 the C20XE runs Motronic M2.5 with a distributor sitting on the end of the cylinder head; from model year 1993 it runs M2.8 with distributorless ignition. In the Kadett C that distributor is in the way, and the recorded answer is exactly that: the M2.8 solves the space problem the distributor creates. For a turbo build one Kadett C project pursued a third route, an add-on control unit with four individual coils to replace the distributor while keeping the engine's own management. On the harness itself no Kadett C source was found. The one detailed wiring account available is written for the Ascona C and works through a body-side connector X17, mapping the engine harness onto it position by position - road speed frequency sender, ignition-live, fuel pump, rev counter signal and engine warning lamp - and notes that the bulkhead grommet on the passenger side has to be enlarged for the larger plug. That mapping is chassis-specific and does not transfer; what transfers is the list of signals a Kadett C builder has to find a home for.
No reliable combination-specific information found on immobiliser, speedometer, tachometer and instrument cluster in this combination.
Status: OPEN
One purpose-made part carries this field. A German maker sells a caliper adapter with which "die belueftete 16V Bremsanlage (Saettel +Scheiben) vom Kadett E, Calibra, Vectra A, Astra GSI /16V C20XE" can be fitted to the Kadett C in saloon, coupe and City form as well as the Manta B and Ascona B - i.e. the donor car's own vented brakes move across with the engine. The disc centre bore has to be machined out to 70.10 mm, 14-inch wheels can still be used, and the price is 195.08 EUR as of 25 July 2026. The maker supplies a material certificate and states that registration with the TUEV is possible if fitted correctly, while at the same time describing the part as developed for motorsport and requiring individual approval under §21 StVZO. The older forum route to the same end is a complete front axle from a Rekord E 2.2i. From the Ascona C conversion guide, transferred rather than proven for this car, come the target figures of 256 x 24 mm vented discs at the front with rear discs, a 21 mm front anti-roll bar and a 17 mm rear bar.
Status: VERIFIED · Confidence 82%
Four documented problem areas, three of them specific to this conversion and one to the engine itself. The engine problem first, because it decides whether a cheap donor is cheap: the C20XE cylinder head exists in a CosCast casting and in KS/Kolbenschmidt castings, and they do not behave alike. The KS 400 is described as too soft - it "faellt ein an den Zylinderkopfverschraubungspunkten" - while the KS 700 is harder than the CosCast head and, in the words of a supplier who sells a repair sleeve for exactly this, "Reisst sehr oft, da zu hart". The failure is a crack between an oil and a water gallery which pushes oil into the coolant, and the tell-tale is light brown oil sludge in the header tank. CosCast heads are described as thicker-walled and generally trouble-free, but the same source is explicit that "Der Oel-Wasserschaden kann bei allen auftreten". Second, the gearbox: the only factory gearbox that bolts on unmodified is rated below the engine's torque, and a Kadett C source calls it "schon etwas ueberfordert" with 150 PS. Third, the rear axle: the aluminium neck and the axle extension are named as the parts that fail. Fourth, packaging, twice over - the oil pickup pipe through the Manta pan, where one builder reports "Es ist quasi unmoeglich das Oelsaugrohr da durch zu fuehren", and the engine mount position, where using the two forward holes is not possible without working on the bulkhead. No source in this run reports a conversion that was abandoned or reversed.
Status: SUPPORTED · Confidence 76%
No reliable combination-specific information found on the approval prospects for this combination in Germany.
Status: OPEN
Germany, as of July 2026. No source was found on the actual approval of a C20XE or C20LET in the Kadett C; the following information is general, but unusually pertinent for this vehicle because two procedures meet here. First, the modification inspection (Aenderungsabnahme): TUV SUD states that the Betriebserlaubnis may lapse if modifications change the vehicle category, may be expected to cause danger, or worsen emissions and noise behaviour, and that a modification report under § 19 StVZO "may be required even" "where an ABE, EC marking or Teilegutachten exists"; engine tuning is expressly named as a modification requiring inspection. TUV Rheinland expressly lists "vehicles with conversions for special purposes" as a case for individual approval (Einzelabnahme) under § 21 StVZO, requires that "the officially recognised expert must carry out all necessary tests and examinations himself", and summarises: "no registration without a positive report." The only supplier found of a combination-specific part - a brake caliper adapter for the Kadett C - supplies a material certificate with it, declares registration possible "with correct installation", and at the same time expressly names Einzelabnahme under § 21 StVZO as a prerequisite for road use, because the part was developed for motorsport. Second, and decisive for this vehicle, the H-Kennzeichen: the Kadett C was built from 1973 to 1979 and therefore falls squarely within the classic-vehicle question. TUV Rheinland requires for the H-Kennzeichen a "condition worth preserving" overall and a report under § 23 StVZO, and permits conversions only to a limited extent: "Period repair work or conversions (within ten years of first registration) are also acceptable." Against that stands the engine's production period: the C20XE was presented in 1987 and reached the market in the second half of model year 1988. Whether these two periods overlap for a particular vehicle depends on its first-registration date; none of the sources found draws that conclusion, and it is not drawn here as a substitute, per § 5 of the research rules. A German conversion guide for the same engine puts the practical consequence as follows: "Especially with a later H-Kennzeichen in mind, you should enquire very precisely; problems can arise later here", and recommends consulting TUV or DEKRA before the conversion. On inspection practice there is only one source, and it concerns a Kadett E Cabrio with the same engine - there the inspector demanded proof of the donor vehicle's brake system from the manufacturer's documentation, and a copy of another vehicle's registration document was expressly described as unsuitable. Nothing was found on the emissions classification of a 1988 engine in a vehicle from 1973 to 1979 and the resulting key numbers - with this conversion that is the most critical open question.
Status: SUPPORTED · Confidence 60%
https://epytec.de/blog/535-einbauanleitung-manta-ascona-kadett-16v-umbau-motorhalter-c20xe-c20ne-motor-halter-motorumbau | https://epytec.de/opel-kadett-c-coupe-manta-ascona-16v-c20xe-scheibenbremsen-adapter-vorderachse-bremssatteladapter-bremssattel-310 | https://www.seyfang-kfz.de/p/reparaturhuelse-zylinderkopf-ks-700-cossi-c20xe-c20let | https://www.tuning-beimel.de/produktkatalog/auspuffteile/rennsport-auspuffanlage-detail
https://www.youtube.com/watch?v=6Y3nLQB10sw | https://www.youtube.com/watch?v=kDIFU-suxh8 | https://www.youtube.com/watch?v=KyZQbR3l0mA
https://www.motor-talk.de/forum/kadett-c-mit-c20xe-welches-getriebe-t674153.html | https://kadett-forum.de/thread/41047-c20xe/ | https://kadett-forum.de/thread/40710-hinterachse-standfest-bekommen/ | https://www.opel-turbo.de/threads/c20xe-im-heckantrieb.78051/ | https://www.opel-turbo.de/threads/c20let-im-kadett-c.124013/ | https://www.opel-turbo.de/threads/oelansaugrohr-z20let-aendern-f-1-8er-manta-oelwanne.121222/ | https://www.opel-turbo.de/threads/welches-getriebe-am-c20xe-let-hecktriebler.57493/ | https://www.opel-turbo.de/threads/c20xe-umbau-mit-automatik-af20-moeglich.69933/ | https://www.opel-turbo.de/threads/eintragung-c20xe-in-kadett-e-cabrio.82308/ | https://www.classic-opel-forum.de/thread/16443-umbau-auf-2l-16v-c20xe/ | https://www.classic-opel-forum.de/thread/5825-hinterachs-lexikon/ | https://www.classic-opel-forum.de/thread/7416-tankumbau-auf-einspritzer/ | https://www.motor-talk.de/forum/zylinderkopf-c20xe-t2083418.html | https://www.ascona-info.de/C20XE_Motor.html | https://www.ascona-info.de/C20XE_Umbau.html | https://www.calibra-team.de/modules.php?name=kaufberatung&sop=printpage&artid=4 | https://www.calibra-team.de/modules.php?name=kaufberatung&sop=viewarticle&artid=7 | https://www.turboandstance.net/9-500rpm-opel-kadett-c20xe-swap-300hp-730kg-itb-sound/ | https://www.auto-motor-und-sport.de/marken-modelle/opel/kadett/c/technische-daten/ | https://www.tuv.com/germany/de/kfz-gutachten/oldtimer-h-kennzeichen.html | https://www.tuv.com/germany/de/einzelabnahme.html | https://www.tuvsud.com/de-de/branchen/mobilitaet-und-automotive/tuning-eintragungen-und-aenderungsabnahmen
38 findings from 20 hosts, mapping to 20 publisher keys - no key collapses wrongly. 31 findings are reachable, 7 are not. 25 findings are used in substance and cited in fields; they are spread across 13 publisher keys. 21 search runs; every finding used was opened and read. This record is the first that rests almost entirely on German-language sources: 35 of the 38 findings are German-language, of which 29 reachable, spread across 14 German publishers outside the video platform. It is carried by a German parts manufacturer with its own installation guide and a combination-specific brake adapter (epytec.de), four German forums (opel-turbo.de, kadett-forum.de, motor-talk.de, classic-opel-forum.de), two model data sites (ascona-info.de, calibra-team.de), one vehicle data sheet (auto-motor-und-sport.de), two further suppliers (seyfang-kfz.de, tuning-beimel.de) and three legal sources (tuv.com twice, tuvsud.com). Three notes on the counting. First, the most important limitation: six of the findings are at opel-turbo.de and are a single publisher. The same applies to three threads at classic-opel-forum.de and to two each at epytec.de, motor-talk.de, kadett-forum.de, ascona-info.de, calibra-team.de and tuv.com. No field with status VERIFIED or SUPPORTED rests on one of these keys alone. Second, for the four findings from the Kadett C forum the checker normalises to forumromanum.com, i.e. to the host rather than the forum; that carries no weight because all four are unreachable. Third, the five AUTO fields carry no source_ids because the checker flags that as a contradiction under NOT_APPLICABLE - the evidence for the AF20 automatic gearbox and part numbers 90470824 and 90297802 is therefore in the note of those fields, and the finding is in the source list under the id ot-automatik. Thirteen findings remain uncited: the 7 unreachable ones, the three YouTube links (per § 5 not technical evidence), the automatic finding (see above), the C20NE/C20XE FAQ at kaoscrew.de (reachable, but it concerns the Corsa with front-wheel drive and a transverse engine - a different layout under § 4) and a blog page on engine failures (reachable, but with a recognisably general problem list that mentions, among other things, a timing chain, without the C20XE valvetrain having been clarified in this run). The heaviest loss of this run is the two sources that should have carried this record: the C20XE conversion and parts list at kadett-c-limo.de, unretrievable because of an expired SSL certificate, and the entire Kadett C forum on forumromanum.com, HTTP 404 throughout in four attempts with four different threads - including one thread each on registration, on the H-Kennzeichen and on driveshaft selection for exactly this combination. Added to that is an archived Kadett C thread on the fuel pump that returned only the forum host's home page. Precisely the answers to the fields now marked OPEN are therefore missing.
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ECU