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12 Posts
Discussion Starter · #1 ·
hello to All,
i've been reading the posts for quite some time now and would like to ask for advice to find and match the parts which work together and give the best result. Sorry in advance for entering a long post and making lots of questions but i have quite a few alternatives and don't want to make unnecessary experiments. if something is not recommended at all, we won't try it...
target: have a car with good acceleration in traffic (it's not a racecar).
start from the beginning:
1. i have an old Manta A, with the 3 speed automatic, open diff of 3.44 ratio ('big' axle). i'd like to keep the automatic transmission. in the past i also bought a small axle with 4.11 but so far we have not used it. i would expect automatic works better with a lower ratio (like 3.44) - as in our case it remains in 1st gear up to 70 km/h when throttle is floored. with a higher ratio rear end it would shift earlier... Recommendation: leave the 3.44 or try the small axle with higher ratio?
2. Now engine is a 2 liter, fuel injected. lately we have reworked the cylinder head: installed 2.2 valves (45 mm inlet and 40 mm outler) and put a regrinded cam in (unfortunately i have no info about duration), just noticed valve lift was higher. Also with an adjustable timing gear. So far we don't have much experience (we did not drive during winter). Lately i have bought a complete 1.6 engine. i was told 1.6 engine with 2 liter valves is the best combo - 1.6 has the smallest combustion chamber so results in highest compression ratio. we could insert 2L valves with little work - for 2.2 valves we would need to remove a lot of material (unshrouding).
Which way is better? higher lift cam, big valves or smaller valves but higher CR?
Have also read in 'Opel Hi-po cyl. head comparison': >>A 2.0 head has the same port locations as a 1.9. It has slightly larger valves than a 1.9, but barely better airflow. For my money, if I were going to install larger valves and modify a head for power, I'd rather use a 1.9 head than a 2.0 head.<<
>>And the 2.2 head is crappy on the exhaust side as it is (only 77 cfm, a 1.9 head would smoke it with the same sized valves). << i think it was intentionally restricted to give better low torque. but for an automatic do we really need good low end torque?
i can't immagine which one an automatic transmission like: something with good low end torque to pull the car, so that converter could not overload/stall the engine - or an engine with higher power at higher rpms, as if you want to go faster, you floor it to rev the engine (otherwise an automatic does not accelerate). so don't know which one would be the best option.
3. about cam... once RallyBob said for an automatic, the best option is the cam from a19S. i found a chart at Customs-n-classics.dk
it says max torque is at 2600 rpm. all the others have max torque at higher rpm.
is it the reason why it works better with the automatic? if we use different cam with the adjustable gear, we can advance it to have max torque at lower rpm... fortunately i have a 19S engine in pieces, so i have the 19S cam available... so still the 19S cam is recommended or if we can adjust, could we use 'anything' ?
4. exhaust manifold. now we have the stock exhaust system slightly modified: (with only one (straight-through) muffler at the end). i also have a 4-to-1 custom manifold. runner lengths are not perfectly equal: made a rough measurement with a measuring tape, they are about 52-54-55-61 cm long. more or less. so like almost 20% difference between shortest and longest. how much does it count? is it strictly compulsory to have the exact same length or is it still far better than the original (2-to-1)? then they combine in a tube of 60 mm. if this manifold is okay, we would intend to create and install 60 mm tubing all the way to the back. question is again: what is better for an automatic: higher revs requires greater diameter. but for lower speeds 60mm diameter maybe too big, exhaust flow will be lazy causing too much restriction?
5. finally the 'lower' part, the crank itself. as mentioned, now it's a 2 liter. but i also have a 2.2 liter engine. i know, there is no replacement for displacement, but again, for an automatic, which one is better? a 2.2 liter with greater torque or a 2 liter (revving, swift) - if an automatic requires more revving...
ok, perhaps now you say i asked too many questions and ask for a good receipt. as mentioned in the beginning - i just want to avoid unnecessary experiments if someone had already gone through or had the experience with a particular setup.(Don't want to reinvent the wheel).
Thanks for thoughts and recommendation.
Gyorgy (from Hungary)

12 Posts
Discussion Starter · #2 ·
pictures of heads

16_16.jpg - see the deposit on the 1.6 used head around the inlet valve. there is not much air flow at that part i believe (dimples could help?)
16_20.jpg - if we were to put the 20 inlet valve in the 16 head. some unshrouding should take place.
16_22.jpg - if we were to put the 22 inlet valve in the 16 head. LOTS of unshrouding should take place, edge of valve head is very close to the wall - but removing a lot of material results in lower compression.

(sorry, forgot to mention: budget is low, want to use the parts i have on hand, can't afford buying special domed pistons...)


Super Moderator
14,163 Posts
You lose a lot of "grunt" with the automatic. Partially because of the gear ratios, and partially because the Trimatic eats about 14 HP compared to a manual gearbox.

So you need as much torque as possible from your engine to work well with the automatic.

I would do this:

>use the 2.2 shortblock.
>use the 2.0 head with the 2.2 valves, and the 2.0 injection.
>use the higher lift camshaft. Advance the camshaft about 3 or 4 degrees.
>use your 4-1 exhaust, and use 60 mm exhaust all the way to the rear of the car.
>use the 3.44 big axle. The small axle is not strong enough for a 2.2 litre engine.

You will probably have 125-135 HP with this combination. I'm not exactly sure because of the camshaft.
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