PDA

Archiv verlassen und diese Seite im Standarddesign anzeigen : 1.8 JH-engine tips?



kapsu
16.07.2005, 22:20
Hi and greetings from Finland!

I have a Scirocco GT2 -90 (and Primera GT -99). I'm quite newbie with Scirocco, just bought it few months ago..

Car has 1.8JH engine with catalysator and it is running ok, although lacks some power.. any hints for that?

Because the laws in Finland, we cannot install turbo nor can we remove the catalysator :/ So what can we do... if anything?

I'll try to add some pics..



Post Edited (07-16-05 21:28)

kapsu
16.07.2005, 22:29
pics,

OSLer
16.07.2005, 22:50
Hello to Finland from Germany!

Nice cars, the Scirocco especially ;-)
For tuning the JH is simply the wrong engine, it would cost too much in effort and money to get this engine running smoothly.
Simple things are of course camshaft ( Schrick for example), the damper from Audi 5 cylinder engine + warmup regulator, flatten the cylinder head or polishing the intake and exhaust area.
But all this won´t let you get far over the 105 hp, i think.


Greetings Lars

kapsu
16.07.2005, 23:26
Hi Lars, thanks for the info..

What do you mean by that damper from Audi?


Any experiences of replacing the original catalysator with a highflow cat? (eg. MagnaFlow or HJS.)

Or rising the compression ratio from 8.5 to 9-10 by changing the pistons from other 1.8 engine, EV/DX etc.?

OSLer
16.07.2005, 23:43
Damper is another word for the air regulator with the flap, maybe throttle(?) the german word for this is Drosselklappe, i don´t know any other or better translation, sorry.

"Or rising the compression ratio from 8.5 to 9-10 by changing the pistons from other 1.8 engine, EV/DX etc."

I think that this is the only way to get more out of this engine, if this is possible for you. Together with the camshaft from Schrick and all other mentioned mods you can get up to 115 hp, if everything is set up correct.
If possible better change the engine to DX, it would be the better base for tuning.
To keep the catalysator regulations clean, just use the puls generator, fuel distributor and the exhaust header of the JH engine.


Greetings Lars

Tempest
17.07.2005, 01:54
Is that you in the first picture, kapsu?

Nice Rocco, and welcome to this forum from the UK-outpost :wink:

Yes, Lars means the Audi 5E throttle body (German: Drosselklappe), but you must use that in conjunction with the matching Audi warm-up regulator.

As Lars has already mentioned, the JH in standard format is not hat ideal for modifications, unless you're willing to invest lots of money and time. Indeed your ideas of increasing the compression are a solution, but by the time you've done it, you would have been better off having strated with a different engine altogether, like the afore-mentioned DX engine (already has a compression of 10:1, not 8.5:1 like the JH).

HTH,

Tempest

sublime
17.07.2005, 02:35
Welcome kapsu,

Most things I whould suggest have already been said, a few members of this board invested time and money into modifying an JH engine with very little effort. The reson is quite obvious when considering the meaning of compression ratio. Compression is directly related to average combustion pressure . The higher the compression, the higher the combustion pressure. This "a.c. pressure" is the most significant attribute for efficiency of an engine. By raising the efficiency, you get more horsepower per fixed amount of fuel/air mixture. It's one way of classic tuning. The other way is to raise the amount of air/fuel mixture sucked into cylinder and another way is to raise the rounds per minute at which the peak torque is available.

You see, by driving a very low compression, lower than the engine layout whould allow at most, you suffer a bad efficiency. This also relates to every tuning attempt you start. As on the one hand a sharp camshaft of about 272° whould boost the max. power of an DX another lets say 10HP up, on the other hand a JH whouldn't be able to use that amount of more air/fuel mixture just as efficient as the DX does, resulting in a lower HP gain (lets say 6-7HP).

Thinking about higher compression should be the first step if serious HP gains are wanted.

Greetz
Chris

kapsu
17.07.2005, 11:28
I'm not looking for a rocket, merely checking that what can be done. (Our Primera (150ps) beats it 10-0 :( )

I bought the Scirocco mainly for the looks, great classic =) Scirocco is really a rare car here in Finland.. there wasn't many to choose from. All the originally imported DX and KR/PL models were in pretty awful condition. In the recent years people have imported more Sciroccos and they are usually JH (it seems to be the most common in Germany...)

back to topic:
In our local forums I read that the cylinder head is the same on JH and other 1.8l 8v engines, so the lower compression is due different pistons.. which have bigger combustion area. But besides the pistons, what are the other differences to e.g. DX engine?

Could I just change the pistons from a DX/EV/PB or basicly any other 1.8l 8v mk2 Golf engine (plenty on the scrapyard..)? That would be bolt-on change? What else is needed?
I imagine that would be much cheaper than making modifications to the head or manifolds at some high-price workshop..

kapsu
17.07.2005, 11:32
And are there any exhaust manifolds available for JH (that would fit the original catalysator)? I have seen plenty of manifolds for 1.8 8v but..

EDT: I noticed that SuperSprint has manifolds for mkII Golf with cat.. would that fit?



Post Edited (07-17-05 10:55)

GTX
17.07.2005, 11:53
Hi!
replacing the original catalysator with an cat-fake wont get you any 0,1HP.
The Problem ist the fu***ng small outtake-manifold.
I have a EV (same as DX) installed instead of the JH-Enginge. All parts from the FI are still JH.

http://forum.rowi.net/read.php?f=10&i=11522&t=11522

My Engine is the pic under : "Ich weiß zwar nicht was der Sebastian für nen Motor drinhat, aber der drückt auf jeden Fall 108,5 PS nach DIN"


Greetings, Sebastian

kapsu
17.07.2005, 12:15
GTX,

so the 4-1 exhaust manifold of the JH is a bottle neck? what can be done?
Different manifolds available?
here seems to be one with dual outlets:
http://www.techtonicstuning.com/viewpart.asp?partnum=251.101
and matching downpipes as well..

Or just get rid of the whole original front section and get a decent manifold&downpipe and change to high flow cat at same time.. as they wont fit the original cat anyway. hmm, not cheap :/ well, nothing is..

ps. how can I make actual links here?

Angel
17.07.2005, 13:31
hi,
why don't you replace your Jh with an PL? Isn't that allowed in finnland? That's the easyest/cheapest way to get more horsepower.

there are two ways to put links in here:

Link1: http://www.rowi.net (url)http://www.rowi.net(/url)
Link2: RoWiTech (http://www.rowi.net) (url=http://www.rowi.net)RoWiTech(/url)

you must replace the parenthesis () with brackets [] than it will work.

greetz angel

Tempest
17.07.2005, 15:35
>the lower compression is due different pistons

This is correct (even have a nifty picture in a book here showing the 2 pistons, the JH one has a deeper mould in the top of the piston).

The effort in changing the pistons is still considerable given that as Angel has already said, you may very well be better off starting with a 16V block.

This is very unusal for me to say, as I normally am a big fan of the JH engine, well mine at least, as prior to me buying my Rocco with the JH, some other person had already kindly invested bucket loads of money and time in modding that engine (increased the compression by skimming the head, now back up to 10:1 again). So my JH is quite a different story in terms of tuning. But if yours is still totally standard, then even I would have to agree that unless you really want to stick a lot of time and effort into that engine, you are better off getting a DX (probably very difficult in Finland), or some 16V block.

Tempest

GTX
17.07.2005, 16:48
It even makes sense instead of buying a complete DX/EV(from Gollef2) getting an EX(90hp carb enginge) oder an 2H(Gollef1 Cabrio)-Block and put the JH Head on it. Then u will even have the 10:1

kapsu
17.07.2005, 21:56
about the Audi throttle body.. which models have the compatible part?

kapsu
18.07.2005, 13:48
I just checked the throttle body and the holes measured about 36mm and 45mm.. what size is it in the Audi body? It can't be much bigger if it will fit the original manifold & mounting?

While measuring I noticed that the cable was a bit loose and the throttle flap didn't open all the way to the max from the pedal.. and it didn't hit the full throttle microswitch. What does the switch do anyway? (couldn't even find it on some older technical pics..)
Well, adjusting the cable was cheap ;-)

EDT: picture attached



Post Edited (07-18-05 12:50)

Tempest
18.07.2005, 16:18
>It can't be much bigger if it will fit the original manifold & mounting?

The Audi throttle body does have bigger butterfly valves, which hit the opening of the original manifold when you're trying to fully open them. That's why using a Dremel you will have to grind some material away at the opening of the original manifold to make room for the valves to fylly open.

>What does the switch do anyway?

It signals the Lambda control unit to ignore the Lambda sensor readings and enrich the mixture.

Tempest

kapsu
18.07.2005, 16:51
Tempest wrote:

> you will have to grind some material away at the opening of the original
> manifold to make room for the valves to fylly open.

Ok, that is not a problem. It can be attached directly to the original screw holes on the manifold?

What is the correlation between the throttle body and the warm-up regulator, why change both (mentioned above)?

I noticed many 5E units in the eBay.de, have to check the local VAG forums first ;)

> It signals the Lambda control unit to ignore the Lambda sensor
> readings and enrich the mixture.

thanks for the info!

Tempest
19.07.2005, 17:12
>Ok, that is not a problem. It can be attached directly to the original screw holes on the manifold?

Yes, but you just need the extra clearance on the manifold for the larger butterfly valves to fully open.

>What is the correlation between the throttle body and the warm-up regulator,

The Audi throttlebody has an extra vacuum connection that goes to the warm up regulator to further enrich the mixture on demand. Although some people have used the throttle body without the Audi warm-up regulator, the results weren't that satisfying (guzzling fuel etc.).

Tempest

GTX
19.07.2005, 22:29
I think the exhaust manifold from the G1 Cabrio Enginge 2H 98HP will fit, is is a little bigger than the JH one.

Sebastian53b
20.07.2005, 00:50
to get more power ,you can also use the airflow sensor disk, fuel distributer and intake manifold from the eg (1.6 gti engine).

kapsu
20.07.2005, 11:45
Sebastian53b wrote:
> to get more power, you can also use the airflow sensor disk,
> fuel distributer and intake manifold from the eg (1.6 gti
> engine).

Really? I'll keep that in mind.

I have read many texts about the bigger throttle body and changing the ignition distributor from 112hp engine but this was new..

kapsu
20.07.2005, 11:48
Tempest wrote:

about the full throttle switch..

> >What does the switch do anyway?
>
> It signals the Lambda control unit to ignore the Lambda sensor
> readings and enrich the mixture.

hmm, so normally it holds back on the mixture becoz of the lambda.. what if you would modify the full throttle switch to be on all the time?



Post Edited (07-20-05 10:49)

Sebastian53b
20.07.2005, 12:18
i hadn't try it but i will, i only read it in a vw-tuning book.

Mr.Burnout
27.07.2005, 16:55
The easiest way to boost your JH Engine is changing the pistons.
Using EX or DX pistons will boost your Engine up to 105-110 hp, without any more changes.
The difference is that you must use premium gas.

Greetings and have fun
Stefan

Tempest
28.07.2005, 21:16
Can do that, the frequency valve will than permanently run at 50%, slightly rich. Not the best way of tuning the JH, though :zwinker:

Tempest