1.9 Durability Question for Turbocharging

2945 Views 14 Replies 9 Participants Last post by baz, Jul 24, 2005

FrogLightGt

Discussion Starter · Jul 23, 2005

Hello everyone. I have a 73 opel gt with a stock 1.9L. Soon I am planning to complete a total rebuild of my motor with new bearings, rings, gaskets timing chain etc. I was just wondering how much horsepower a freshly rebuilt stock 1.9 rotating assembly could handle. I am considering building a custom turbo efi setup based off of the stock efi manifold using a megasquirt and larger injectors and what not. I was wondering how the stock 1.9L holds up to boost and how much boost I could get away with running on a fresh motor. Any information would be greatly appreciated. Andy

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GTJIM (R.I.P.)

· #2 · Jul 23, 2005

Tuff

The 1.9 Opel motor has an extremely durable forged steel crankshaft with large journals and a short stroke with five main bearings. However your 1973 motor probably has the heavier, but weaker cast rods. For best strength with stock parts you need to find some of the earlier forged steel con rods.
The stock pistons are cast and not up to high boost pressures - you need to fit aftermarket forged pistons. The other problem is cooling - the later head such as you have is well known for cracking when subject to high heat flows.
HTH

Betta Carotene

· #3 · Jul 23, 2005

jim i thought only 74 and up came with the cast rods.

RallyBob

· #4 · Jul 23, 2005

Betta Carotene said:
jim i thought only 74 and up came with the cast rods.

I've never seen a '73 (US-spec engine) with cast rods, and only some '74 engines came with them. All the '75's I've torn apart had the cast rods however.

Bob

tekenaar

· #5 · Jul 23, 2005

CIH Cast rods

Betta Carotene said:
jim i thought only 74 and up came with the cast rods.

Parts book doesn't give a clue, but I thought only the '75 FI engines used cast rods . . . wanna jump in here, Bob?!

RallyBob

· #6 · Jul 23, 2005

FrogLightGt said:
I was wondering how the stock 1.9L holds up to boost and how much boost I could get away with running on a fresh motor. Any information would be greatly appreciated. Andy

Your key concerns are probably going to be the heat created by a turbo. Opels already have a bad intake/exhaust imbalance and some cylinder head cooling issues which create EGT's close to that of a turbo engine, and that's on a bone stock 70 hp N.A. engine! 1400-1580 degrees is not unusual....

New cast (stock) pistons and stock forged rods and crank are pretty capable up to about 8000 rpms. The stock rocker arms are not up the task of high rpms or high valve springs pressures however.

If you upgraded to forged pistons, and improved the intake port airflow, you will have created a pretty damn strong and reliable engine. I know of some folks in Europe making 300+ turbocharged hp from a CIH Opel with just a few mods such as this and an appropriate turbo and EFI system.

HTH
Bob

FrogLightGt

Discussion Starter · #7 · Jul 23, 2005

Wow. You guys rock. I was not aware that my 1.9L had a forged crank and rods. That is really awesome for a stock four banger. I am new to opels and it seems the more I find out about my little beast the more I love her. So I suppose that before I start using forced induction I am gonna have to drop a little money into getting my block prepped. I am gonna get forged pistons and have my bottom end balanced and have my head ported matched to my intake manifold and polished. I have been planning on finding out the specs on the head and connecting rod bolts and checking to see if ARP makes stronger bolts to replace them. I have also been tinkering with the idea of having a copper head gasket made. I have two questions.... I was wondering if anyone knows were I could get stiffer valve springs and stronger rocker arms. I suppose I could have the stock rockers shot peened and freeze tanked maybe. I was also wondering if I could run 9.0:1 compression with boost if i had my EFI tuned properly... Thanks Again... Andy

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GTJIM (R.I.P.)

· #8 · Jul 23, 2005

So ......

tekenaar said:
Parts book doesn't give a clue, but I thought only the '75 FI engines used cast rods . . . wanna jump in here, Bob?!

The change to cast rods was not contemporaneous with the change to lo-compression then? Every motor that I have dismantled ( seven of them ) dated from "74" through "79" has had cast rods. The only earlier motor I have is the original from my 1972 GT - and I have not dismantled that one yet but it has 9:1 flat-top pistons as I can see the valve notches through the spark plug holes. The PO told me she had it upgraded from lo-comp soon after buying the car due to lack of power - the dealer fitted a Weber 32/36 at the same time!
Strangely enough the later motors I have dismantled are all flat top pistons too - all from 1975-79 Holden Toranas - so not quite the same as your 1975 and earlier motors over there.
So ..... Turbocharging the stock lo-comp engines from 1971-74 would be an option as with 7.6:1 compression and forged rods they would be good candidates for this upgrade??? Except for the head heat flow concerns??

As for stronger rockers - have a search for "roller rockers" on this site.

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nobody

· #9 · Jul 23, 2005

If you go to 9:1 your boost potential will be limited a bit. What model are you working with? Without an intercooler you will be limited to around 8 to 10 pounds boost. I've seen the results of too much boost on a 1.9 first hand. Blown Arias 8:1 through both top ring lands is not pretty. Also if this is GT the spacing to put one in is kinda tight.

kwilford

· #10 · Jul 23, 2005

FrogLightGt said:
...So I suppose that before I start using forced induction I am gonna have to drop a little money into getting my block prepped. I am gonna get forged pistons and have my bottom end balanced and have my head ported matched to my intake manifold and polished. I have been planning on finding out the specs on the head and connecting rod bolts and checking to see if ARP makes stronger bolts to replace them. I have also been tinkering with the idea of having a copper head gasket made. I have two questions.... I was wondering if anyone knows were I could get stiffer valve springs and stronger rocker arms. I suppose I could have the stock rockers shot peened and freeze tanked maybe. I was also wondering if I could run 9.0:1 compression with boost if i had my EFI tuned properly... Thanks Again... Andy

Now you are heading down the path of major engine performance upgrades. Before you ask TOO many questions (and raise the wrath of members who are only too happy to answer a new, unique question, but get grumpy when asked to answer the same question over and over again), spend a few hours (or days) and have a read around this Forum, and do specific searches for things like:
"port match" (usually a complete waste of time in a CIH engine, much more to be gained by bigger valves, appropriate, INTELLIGENT port blending, and such),
"stiffer valve springs" (you have to know WHY you want stiffer springs),
"forged pistons" (some choices, but mainly expensive aftermarket Opel-style pistons, or converted Chevy or other aftermarket pistons),
"ARP rod bolts" (virtually NONE available, at least not that I have been able to find),
"head gaskets" (and why do you want a copper gasket?),
"rocker arms" (roller rockers ARE available and arguably worth the money, but I can't say about cryo-treating or shot peening the stock rockers)

You also need to decide on a cam configuration and flywheel weight, not to mention rpm/HP range and other mundane questions BEFORE you embark on a "performance upgrade". As has been said a few times around here, changing one aspect to improve its performance can actually HINDER overall performance is it isn't integrated into the total design.

JM2CW

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nobody

· #11 · Jul 23, 2005

Two threads jump out on this idea.

do a search for these
"Quest for Carlisle" or "winter turbo".

Happy reading

FrogLightGt

Discussion Starter · #12 · Jul 24, 2005 (Edited by Moderator)

Andy
when posting please keep responses polite or they will like this one be removed
baz moderator

kwilford

· #13 · Jul 24, 2005 (Edited by Moderator)

FrogLightGt said:
Hey keith. *****************************************************. Jm2cw
Andy

Well Andy, you have only posted here 4 times, so I don't know what you know. While you may know a lot about performance upgrades to some engines, every engine design has "peculiarities" that a person has to learn. Opel CIH's have more than their share. And that can be learned by trial and error, or by someone teaching you. I wasn't trying to give you a thorough diatribe on Opel tips, just to ask you to use the search function and look for certain aspects.
I am going to suggest that you be cautious of the "tone" that you use when you answer posts. While I may not have the experience and knowledge of RallyBob or "nobody" (two of the gurus of CIH performance on this site), my post didn't deserve the comments that you made. I will take the position that you didn't intend to "diss" me in any fashion, if you take the the same position about my comments. So you know, we do NOT tolerate any personal attacks or flames of even the most seemingly trivial degree. And you should know that I am a Moderator, and can take, well lets say, "positive action" on such matters

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soybean (R.I.P.)

· #14 · Jul 24, 2005

I think Keith and "Nobody" pretty much summed it up. Not being petty, but there is a wealth of knowledge here and a whole LOT of reading on what you are trying to accomplish with the CIH Opel engine. The search engine reveals a lot. Jarrell

baz

· #15 · Jul 24, 2005

did not see your response keith but have taken the post out anyway and will in your reply

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