1.6 rally engine

[bascona]

hello

As i'm looking to build a 1.6 rally engine without spending to much money, i'll mostly try to be using parts i already have.
This is what i've come up with so far:

The block will have a 8 counterweight crankshaft (kept original) with a lightened steel flywheel (all balanced). It will have new bearings and piston rings, but no new pistons.

As for the head i'm planning to build cam, springs and valves from a prepped 2.0 rally head into the 1.6 head.
Valves are 44 (1.73) and 40 (1.57), but i think to cut them down to 43/39 (1.69/1.54) because (especially at the side of the inlet) there isn't much unshrouding possible.
Springs (inlet) have 40kg with closed valve, 65kg at max. lift and 120kg with coil bind.
Cam has 8.51 lift (inlet) and 8.12 lift for the outlet. With 1.51 rocker ratio and 0.30 valve lash this will give 12.5 mm (4.92) of valve lift.
Compression i want to get as high as possible which will be hard with the flat-top pistons. I'll be running pump gas (maybe with octane booster).
Fuel delivery by a pair of 45 DCOE, but with an air box/duct.
Ignition will be a distributor (with adapted advance) from a Manta Gsi (with Hall-sensor)
Furthermore a stock exhaust header with 63mm exhaust, adjustable cam sprocket, electric fan, ...

My questions:
Is this a good combo (valves- cam -springs) ? Mechanical but also in terms of driveability. What can i expect from it: high rpm and nothing below 3000rpm?
Is it worth to work further on this or should i get other valve sizes, cam, carbs, ...

greetz bert

PS: my drivetrain is a 5 gear (0.87) and 5.14 diff. with 13" wheels

[RallyBob]

Originally Posted by bascona As for the head i'm planning to build cam, springs and valves from a prepped 2.0 rally head into the 1.6 head. Valves are 44 (1.73) and 40 (1.57), but i think to cut them down to 43/39 (1.69/1.54) because (especially at the side of the inlet) there isn't much unshrouding possible.

Why not put the 8-cwt crankshaft into a 2.0 block, and fit the 1.6 head? There you'd have the higher compression, greater displacement, and smoother running crank.

Anyway, I'd use larger inlet valves, just unshroud the chambers a bit. I have done this a lot with 1.5 and 1.6 heads, you can still have reasonable compression ratio, plus good airflow. This 1.5 head has 1.85" (47 mm) inlets and 1.50" (38 mm) exhaust valves. No reason to go larger than 1.50" there, the exhaust ports outflow the inlet ports! I realize that if you use the 1.6 block then the 1.85" inlet valves are too large due to the smaller bore, but I would keep them at full size (1.73") and just cut down the exhaust valves. I've been able to get those 1.5/1.6 heads to flow as well as a fully prepped 2.0 head BTW, so they can make some good power.

HTH,
Bob

[SantaClaw]

Ok, for 1.6 liter engine tuning, there is only two sites...


Opel Motorsport: Aktive Erfahrung aus dem Opel Tuning - Risse Motorsport.



You can purchase just about anything there is that you need in order to tune a 1.6 from their site.

And they know their engines, if you give them the specs for the engine you want to build, they can answer most questions you might have...


Most tuning companies doesn't have that many parts for the 1.6, but Risse does.


Also, try contacting Enem in Sweden, www.enem.se he's legendary in the Opel Motorsport circut with his awesome Opel race engines, he specializes himself in camshafts, email enem@telia.com ....

He makes 324 degree camshafts that will fit the 1.6, giving you a workable rpm range of 4000 to 8500 rpm +


Can you give me the engine name ?

Is it the 1.6 S with 75 bhp ?
Or the 1.6 N with 60 bhp ?

[bascona]

@SantaClaw
I'll be starting from the 1.6S engine

@RallyBob
Can't use the 2.0 block. Because i'm a beginner rules say we need to have 3 results (finish) with <1600cc before going any larger.

What about the cam?
It was fitted in a prepped 2.0EH head. I was told it was mounted on a 2.7 block for rally. It's an original cam that has been regrinded.
Can i use this cam for a 1600cc engine or is it only suitable for larger displacements (110° lobe seperation)?
I guess the 12.5mm (4.92) valve lift means power at high rpm?

[SantaClaw]

That cam will work in that engine, especially with the larger valves, I would try to get as little resistance in the exhaust as possible..

Of course. that's if where talking high revs...

There are better cams out there, but that costs money...


It all depends on what type of engine you want...

If you want an engine with mid range torque you should be fine with the stock headers..

If you want more low down torque, get a set of 4-2-1 headers..

If you want a high revving engine, you should get a set of kit car headers, in a 4-1 configuration with extra long pipes before joining to 1.

Lightening the flywheel also does wonders for these engines..


Just be aware that oil pressure\flow can be an issue with the CIH\OHV engines, due to small oil ducts in the head causing the cam to seize..

There is no baffle plate in the oil pan of that engine, get one... A very common problem with those old CIH\OHV engines are prolonged corners, when all the oil goes to one side in the oil pan, and you loose oil pressure...

You could also try contacting CNC Heads - HOME for advice when it comes to valve sizes and machining of the head.

They increased the flow on my 8v ohc with 23,2 CFM, on the exhaust, from 108 CFM to 131,2 CFM and with 20,5 CFM on the inlet 137,9 CFM from to 158,4 CFM....

[ggl]

Originally Posted by bascona @SantaClaw I'll be starting from the 1.6S engine @RallyBob Can't use the 2.0 block. Because i'm a beginner rules say we need to have 3 results (finish) with <1600cc before going any larger.

Then why not just run a near stock 1.6 until you've got those 3 finishes rather than spending money on something as "odd" as 1.6 CIH engine and spend the money on a 2.0 (or bigger) that you can use once you have those 3 finishes ?

Just do some mild work on the head, move the camshaft over perhaps and slap the dual carbs and a proper exhaust on it, nothing you can't move over to the 2.0 again afterwards, that way you won't have to spend money on two engines and we all know you'll be going for the bigger engine once you're allowed to do so

[RallyBob]

Originally Posted by bascona What about the cam? It was fitted in a prepped 2.0EH head. I was told it was mounted on a 2.7 block for rally. It's an original cam that has been regrinded. Can i use this cam for a 1600cc engine or is it only suitable for larger displacements (110° lobe seperation)? I guess the 12.5mm (4.92) valve lift means power at high rpm?

I couldn't read those cam specs you posted, but generally for rally and for better (flatter) torque I would use 104 to 106° lobe separation for such a small engine. With 110° LSA it certainly rev well, but will not have much power low. The high valve lift usually equates to torque, but long duration means rpms, at least in my opinion.

[bascona]

I couldn't read those cam specs you posted, but generally for rally and for better (flatter) torque I would use 104 to 106° lobe separation for such a small engine. With 110° LSA it certainly rev well, but will not have much power low. The high valve lift usually equates to torque, but long duration means rpms, at least in my opinion.

That cam will work in that engine, especially with the larger valves, I would try to get as little resistance in the exhaust as possible.. Of course. that's if where talking high revs...

So i hear both torque and revs in the above answers.
By playing with cam timing, carb settings with long intake runners and filterbox, ignition timing, ... wouldn't it be possible to have a smooth(er) revving engine?
I do want some revs to push the 5.14 diff., but i dont want any gaps or dead points at low rpm. For example when accelerating from a tight corner ... Neither do i want an explosion of hp (with 1.6?) at high rpm.

Just be aware that oil pressure\flow can be an issue with the CIH\OHV engines, due to small oil ducts in the head causing the cam to seize.. There is no baffle plate in the oil pan of that engine, get one... A very common problem with those old CIH\OHV engines are prolonged corners, when all the oil goes to one side in the oil pan, and you loose oil pressure...

That wont be a problem. My daily driver even has one, including the raised oil level in the head.

@RallyBob
Couldn't you open the attachment? It's an Excel-file.
I'll try to post numbers/degrees instead of a graphic.

[Hiro]

Originally Posted by bascona hello As i'm looking to build a 1.6 rally engine without spending to much money, i'll mostly try to be using parts i already have. This is what i've come up with so far: The block will have a 8 counterweight crankshaft (kept original) with a lightened steel flywheel (all balanced). It will have new bearings and piston rings, but no new pistons. As for the head i'm planning to build cam, springs and valves from a prepped 2.0 rally head into the 1.6 head. Valves are 44 (1.73) and 40 (1.57), but i think to cut them down to 43/39 (1.69/1.54) because (especially at the side of the inlet) there isn't much unshrouding possible. Springs (inlet) have 40kg with closed valve, 65kg at max. lift and 120kg with coil bind. Cam has 8.51 lift (inlet) and 8.12 lift for the outlet. With 1.51 rocker ratio and 0.30 valve lash this will give 12.5 mm (4.92) of valve lift. Compression i want to get as high as possible which will be hard with the flat-top pistons. I'll be running pump gas (maybe with octane booster). Fuel delivery by a pair of 45 DCOE, but with an air box/duct. Ignition will be a distributor (with adapted advance) from a Manta Gsi (with Hall-sensor) Furthermore a stock exhaust header with 63mm exhaust, adjustable cam sprocket, electric fan, ... My questions: Is this a good combo (valves- cam -springs) ? Mechanical but also in terms of driveability. What can i expect from it: high rpm and nothing below 3000rpm? Is it worth to work further on this or should i get other valve sizes, cam, carbs, ... greetz bert PS: my drivetrain is a 5 gear (0.87) and 5.14 diff. with 13" wheels

this cam profile is specific:
inlet lift is much higher than exhaust lift,
don't know about durations because I can't read the degree values.
also beware that lift @ TDC is 4.5mm,
so better chech your valve to notch clearance.
IMO don't invest too much money into this 1.6 CIH,
do the first 3 races with a near-stock 1.6
then build a nasty 2.5 as parts are very easy to find in your country!
HTH,
Hiro

[RallyBob]

Originally Posted by bascona @RallyBob Couldn't you open the attachment? It's an Excel-file. I'll try to post numbers/degrees instead of a graphic.

Can't do it from this computer, no excel program.

[ggl]

Originally Posted by RallyBob Can't do it from this computer, no excel program.

There's a perfectly good, free alternative if you don't want to spring for a second copy of MS Office

download: OpenOffice.org Download

[RallyBob]

Originally Posted by ggl There's a perfectly good, free alternative if you don't want to spring for a second copy of MS Office download: OpenOffice.org Download

Still can't do it. Company computer, not allowed to download anything!

[bascona]

Here are numbers and degrees of the cam

Cam 1:
duration: 320°
lobe max. Inlet: 8.52mm (3.35) Exhaust: 8.12mm (3.2)
lobe seperation: 110°
lobe lift at TDC Inlet: 4.59mm (1.81) Exhaust: 1.45mm (0.57)

I've found another cam with more moderate specs. Maybe this one is more suitable?

Cam 2:
duration: 300°
lobe max. Inlet: 7.93mm (3.12) Exhaust: 7.78mm (3.06)
lobe seperation: 105°
lobe lift at TDC Inlet:4.37mm (1.72) Exhaust: 0.71mm (0.28)

I will also (re)post both graphics because some degree numbers seemed to have been disappeared...

@Hiro
Only the first number of the degree value is shown in the graphic. The last number(s) must have been 'slipped off'.
So the degrees are 0-40-80-120-160-200-240-280-320-360-...

I've also noticed that it is better to measure cams by 5° instead of 10° Especialy for a correct valve-notch clearance...

[RallyBob]

Originally Posted by bascona Here are numbers and degrees of the cam Cam 2: duration: 300° lobe max. Inlet: 7.93mm (3.12) Exhaust: 7.78mm (3.06) lobe seperation: 105° lobe lift at TDC Inlet:4.37mm (1.72) Exhaust: 0.71mm (0.28)

I like this cam better for a 1.6 litre engine. It's also better suited for rally use. The first cam would work more like a circuit racing cam...very peaky power delivery.

Assuming it is installed 'straight up', it has this timing:
Intake opens 45° BTDC, closes 75° ABDC
Exhaust opens 75° BBDC, closes 45° ATDC
It has 90° of overlap.

The first cam would have 100° of overlap, even with the wider lobe separation!

Bob

[bascona]

hello

here are the graphics of both cams. Sorry it took so long, but i had a few problems on posting the graphics: Disappearing numbers, jumping graphs, ...

The first thing i'll do is a quick fit of the valves to check piston clearance and springpressure.

Thanks for all the replies. Now i know at least where to start from ...
I'll make a post with the outcome when the engine is ready, but i'll probably pop up before that with some other questions ...

bert