48 replies to this topic

[costasa]

lamchop77, on 13 January 2012 - 01:23 PM, said:

<sub>Costasa

For your info, was looking at wossner pistons the other day and i think they now do a long rod version of the 2.0 piston. I haven't contacted them but i think this is using the 2.0 crank 2.4 134mm rods and then the long rod piston. this i think would be your easiest solution and would give a good rod ratio. If you are going to use std rods get them shotpeened along with the crank as this stress relieves and also improves the strength of the rods/crank.

A word of caution as well, alot of the CIH pistons are designed to be used with the 2.0 style head so the crowns of the piston match the 2.0 combustion chamber. The 2.2 combustion chamber is a different shape for unshrouding the valves, this means that the piston crown can actually make contact with the head depending on how much the head/block have been skimmed. This is easily remidied by relieving the edge of the combustion chamber to clear.

Montza

Not sure about the 1.9 blocks being better on cooling as i have looked at all the different ones and they all seem to be the same, is it a known fact or something that is assumed? I only ask because therecould be another explanation for it. Got this info from Hiro on opel tuners. When the blocks are bored the head and gearbox are not attached, when bolted up they could actually deform the bores slightly so they are out of tolerance and as you say it is always no 4 bore that picks up or fails. Thing is when running forged pistons your looking at a 0.0035" piston to wall clearance which is tight so a 0.0001" movement could cause the piston to pick up as the block heats up. I have noticed that most engines suffer from cooling issues between 2 and 3.

I made up a thick boring plate so that headbolts could be torqued up to full tightness before boring, also did the bellhousing bolts as it was thought that this could also affect it. Had it measured numerous times whilst being bored and it didn't shift with the plate on. Engine guy also said that the boring machine seated better with the boring plate.

Cheers

Chris</sub>

Hi Chris,

Thanks for the info, that is good news if wossner is doing 2.0 pistons to the long rod version, and for the tip to check the combustion chamber with the top piston crown.

What type of pistons that you prefer flat top or with crowns? I have reading some topics in opelgt forum and rallybob use a lot flat pistons.

thanks
Samuel Costa

[lamchop77]

Samuel

i think flat tops are the ideal route to go BUT you cant get high comp ratio without crowns. Had a set of custom pistons done with the help of Dave Powell at performance unlimited. He works on alot of yank V8s which have a similar piston/combustion chamber set up. Basically he recommended that if you do have a crown to increse the comp ratio keep it as minimal as possible as it can interfere with flame propogation across the cylinder. Wossners seem to have a good following and are nicely made.

Rallybob is a wealth of knowledge but he has access to a different pool of engines. He tends to use earlier heads with small combustion chambers and mods them with impressive results although he has used 2.2 motors. In England i have access to 2.0/2.2/2.4 so if i want to up the ratio the easiest route is to use the crowned pistons.

HTH

Chris

[611]

Have been reading this tread for a while now as its interesting to hear all the different stuff about tuning they old CIH. Was thinking about doing some work on mine while its apart but its all getting very techy!
I have a 1.9 taken out to a 2.0 and have a head of a 2.0l B that i was told had been ported and had bigger valves, it has X20 stamped on the side. Does anyone know what the standard valve sizes were for 2.0l?
Im running a mild road kent cam, and will be running twn 45 throttle boddies with full injection (weber alpha).
The engine is in bits at the moment and i have had it all wash, bores honed and the head skimmed to remove a little bit of corriosion.

I dont want to spend too much more on the engine as i still have lots of bits left to do on the car so the question is:
Just put it all back together and drop it in?
or is there anything i can do to add a little bit of extra performance that is easy to do and wont cost too much?
Any thoughts would be great.

Thanks  Andy
www.theopelproject.com

p.s got a limited slip diff in it that i got from an auto a while back if that makes any difference to what i do?

Edited by 611, 15 January 2012 - 10:50 PM.

[lamchop77]

Andy

Think the std size 2.0 valves are something like 41mm inlet 36mm exhaust can't remember off the top of my head. Bigger valves will usually be 45/41. I assume the cam is a OP214. Should be fairly good with the 45 throttle bodies.

For extra performance get the whole thing lightened and balanced, clutch,flywheel,crank and front pulley. Get the flywheel skimmed down to lighten it before the balance. Min thickness anywhere on the flywheel should be no less than 12mm when finished. You could do the rods as well getbthem all weight matched, i have a set already done that were on the forsale section on here. This work will give you a free revving engine with better throttle response. Only other thing would be to up to an OP234 you should be easily on 150+bhp.

Dont waste money on a 4 branch manifold the std cast one is fine.

HTH

Chris

[611]

Hey Chris
Thanks for the info. I have measured the valves and they are 44mm inlet and 36mm exhaust. So might have had some work done.
I will have to look into the option of getting it all balanced. Do you have any idea of a rough cost?
I already have a 4-1 manifold that I got from the US as before the car was taken apart for the rebuild it had twin carbs with 4-2-1 exhaust which was crap, so I'm going to make a new stainless system this time. I think the cam is the one you said as didn't want to go too wild as there wasnt much clearance when running the carbs so didn't want it too rough on tick over. I think I might have a bit more room running the throttle bodies so might be an option. Again it's down to cost as have to get the wheels refurbished and all new tyres and have spent a small fortune on it so far :-)

How much were your rods that you had for sale?

Andy

[garymanc]

611, on 15 January 2012 - 10:50 PM, said:

p.s got a limited slip diff in it that i got from an auto a while back if that makes any difference to what i do?

did not think a auto had a lsd

[lamchop77]

Andy

Sounds like its had the 45mm 2.2/2.4 valve thats been fitted, good mod and with a bit of a clean up of the ports can see good power gains. Price for l+b is about 85-100 quid but can be more, ring round a few places see mif they do it near you.

Rods were up at £40 and they are weight matched to a gram, no takers so make me an offer if you want.

Garymanc lsd's were a factory optional extra so a lucky find methinks!!!!

Chris

[611]

Hey garymanc
As chris says its was a special option you could have fitted to the A. And yes chris it was a lucky find, i broke a rusty auto and kept lots of bit (one being the axel) and it sat at the back of the garage for about 3 years and it was only that someone was looking for an axel that i dug it out to see what it was like ( i hadnt used it as one of the spring hangers was rusty) and when i took the diff cover off i thought ooh look at that! one factory limited slip diff :-) best opel find i've had!

Chris it looks like the head has had the ports cleaned up as they are nice and smooth. Is £25 + postage too low for the rods? and im not much of an engine expert but will they just fit on in place of mine? or do i need to check what ones i have on mine first?

Andy

[costasa]

lamchop77, on 15 January 2012 - 09:21 PM, said:

Samuel

i think flat tops are the ideal route to go BUT you cant get high comp ratio without crowns. Had a set of custom pistons done with the help of Dave Powell at performance unlimited. He works on alot of yank V8s which have a similar piston/combustion chamber set up. Basically he recommended that if you do have a crown to increse the comp ratio keep it as minimal as possible as it can interfere with flame propogation across the cylinder. Wossners seem to have a good following and are nicely made.

Rallybob is a wealth of knowledge but he has access to a different pool of engines. He tends to use earlier heads with small combustion chambers and mods them with impressive results although he has used 2.2 motors. In England i have access to 2.0/2.2/2.4 so if i want to up the ratio the easiest route is to use the crowned pistons.

HTH

Chris

Hi Chris,

Thanks for your reply, it is great to learn more and knowing diferent opinions and routes.
I'm trying to set a main goal to my engine and i'm open to study all the options and the use off chevy parts as rallybob use is a good option because we can buy at good price the parts in us ebay the only problem it will be the custom fees.

Samuel