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Need Help With 18S Ohc Engine

young kadett kinin

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hello, i have a manta a with a 1.9 cih engine and im in the middle of restoring a 1.8 18s manta b and im looking to do some mild modification to the engine i was thinking about a high lift cam and a pair of twin 40 webers

-is there such a thing as a high lift cam for this engine

-iv seen a manifold for to convert a 1600/1800 cavalier/astra to twin carbs iv looked at the bolt patern on both manifolds and the look very similar but i cant be sur can any one verify this

-are there any other modifications i can do to this engine to squeez a little bit more power out of it

any help would be much appreiciated!


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I'm using the 1.8s block and the 1.8E cylinder head with the injection system, when fitted with the 1.8s head and a weber carb it had 110bhp, the injection set up has improved the performance. You could always fit the 2.0 8 valve engine or the 16 valve if you want more power.

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i dont really want the hassle of wiring i want to keep it as simple as possible.

-would i have to use an ecu if i went for the 18e injection set-up?, is there much wiring involved

-if i had the 18e head and injection system are there any other mods i could do to get more than the standar power of an 18e(113bhp)?

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put the astra gte mk1 1.8 head and cam on it with manta cam carrier for dizzy set up, twin 40 dellortos are better than webber jetting is more precise. you can use the 2.0 carlton/cavalier/astra engine use the manta cam carrier again and dizzy. inlets between 1.8 ans 2.0 are easily available for either head but are different cos of the inlet ports in different places. 1.6 and 1.8 inlet is same. the injection is good but limited as its not chipable or mappable so stick with carbs for power but injection for better economy. the cam from the gte head is best you can get unless you rev it past 6500 all the time.

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With a fast road cam and twin 40's (I would assume a decent exhaust too) you'd pass the 113bhp quite easily. Like you I wouldn't want to ruin the simplicity of the carb and have the complication of fuel injection, but to be honest I think twin 40's are a bit major also. For a 'bit' more power you'll only need a 'bit' of a better carb and yes you could get camshaft options for the 1.8S standard engine, but the weedy 90bhp is only really down to a strangled air intake, a poorly built carb and the exhaust is common for the time but not ideal for efficient gas flow.

As Greg said he got 110 quite easily and I had a 1.8S exclusive with the weber DTML (not even a performance carb) with K&N, standard head with a mild skim and sportex exhaust which showed 115bhp on the dyno. Also had the best of everything else, leads, plugs, dizzy, oil and timed for 99RON fuel which on there own don't make a difference but apparently add up to a little extra..

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aggreeing with what already been said ...the most noticable increase in power was from fitting the 18e asrta mk1 gte 1800i head and cam shaft , started off with the varajet and eventually got a weber 32/36 dgv and that really sorted out those crappy choke problems and gave better top end .

i did try a 2.0 block with the mk1 gte 1800 head and it didnt work very well , the CR was way high and ignition timing went out the window .

it could possibly work the other way round , 1800 block and 2.0 head . and i just happen to have a modified manta 1800 manifold to fit the 2.0 injection head , so you can still use a carb and not get too technical with injection and wiring etc.

so the parts are here if you wanted to wack a 2.0 head on it and see how that works ...it would be uncharted teritory as far as i know .

possibly pie in the sky ...what head gasket would you use etc ...???

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if i was doing this again i would just by the hybrid manifold off dynamite dan for the 2.0 head put a full 2.0 engine from a carlton/cav/astra in and put an electric pump for the fuel much easier. 1.8 with 2.0 head dont go unless you are running a low boost turbo or supercharger, chamber in 2.0 head too big for standard 1.8 normally aspirated. i have tried/looked into them all over time.

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2.0 seh is the 130 bhp version the "h" for high out put .(is the one you want)

the other variations 20ne etc all have a few less horses 122,124 .

bhp figures are assuming the standard injection fitted not carbs .

looking back on what i done with the 1800 , yes the head, cam and carb changes made it better and have more grunt ... but it never felt like enough to me . it was just a taste of what it could be .

finally now with the 2.0 and r1 carbs it seems right ,like thats what it should have had from the begining .

you would need better front brakes also .

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  • 2 weeks later...

2.0L ne is 115bhp standard.

2.0L Se is around 122 - 124Bhp standard

2.0L SEH is around 127 - 132Bhp standard.

I would look for a pre 93/94 carlton and get the 2.0L SE engine. Easier to find now than the SEH and cheaper too.

A standard 1.8 is a good engine but for more power and torque it's a lot easier to just put the 2.0L in.

I would install the standard fuel injection. It's very easy to do, will give better economy, cold starting, and generally better power/torque through the rev range than 32/36DGAV, or similar, carb.

A decent twin choke Webber may give a slightly higher peak output than standard fuel injection but it will never drive as well.

It's only when you start fitting a single choke per cylinder that you will see bigger power figures. But even then i would go for throttle bodies and stand alone management system.

Carbs are dead, fuel injection is KING.

Just my opinion.

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