Isuzu turbo diesel tuning guide

[Jack]

I'm not making this to compete with the one on VXON, I'm just making it because I'm bored.

There are two stages to this.

1) Removing the white ring from the fuel pump. This can be done in it's own for a nice increase in semi-open throttle response.
2) Increasing the boost and upping the fuel.

1. Removing the white ring.

The fuel pump on Cavaliers with the Isuzu engine is underneath the inlet manifold. This means the manifold has got to come off.

The collection box on the top of the manifold is secured by four 6mm bolts with 10mm heads. The air filter is also in here, the one that people forget about.

Once this is off, you can remove the hose to the air box which is held on with a jubilee clip, and the hose from the other side.

The manifold itself is held on with torx-headed bolts (some longer than others, so remember which ones are from where). I didn't have any sockets to fit, but IIRC a 5/16th socket fit very tightly.

You might have to loosen up the union on injector one to get a socket past it.

The easiest way to see what needs removing from the bottom edge of the manifold is by using a mirror, or I used my phone with the light on. There isn't much space down there, and there will be swearing,

You will have to remove the feed from the turbo as well, this is simply two bolts, but they are a pain to get to and they are different lengths.

You will need a new inlet manifold gasket and a new gasket from the manifold to the turbo feed.

[Jack]

Once the manifold is off, you can clearly see the fuel pump.

The cover you want to attack is held on by four 6mm bolts with 10mm heads.

Keep these somewhere safe and clean.

Gently pull the cover off, and underneath you will be greeted with the diaphram. You will need to (very gently) pull this up and pull the entire plunger out from the fuel pump.

Make sure you don't rotate it, as the orientation of this plunger determines the fuelling for the entire rev range.

Gently slide the white ring down and off the plunger, and put the plunger back into the fuel pump exactly how it came out.

While you have such good access, it might be worth taking the anti-tamper cover off the maximum fuel screw. I didn't do this, so I will have to attack it with the manifold on.

Now do the entire lot in reverse, renewing the inlet manifold gasket and the gasket to the turbo feed.

This is the ground work for further tuning done.

[Jack]

Stage 2 will come later, possibly Wednesday.

[ANDYRACER]

Update your thread Jack, want to get my bleed valve fitted tonight.

[elgan]

did they make an izuzu engined late cavalier cdx with all the toys? that would be a nice budget smoker.

[CraigGreen]

Yeah but good luck finding one.

The expression 'Hens teeth' springs to mind. lmao

[elgan]

oh it'd have to be a nice grey colour saloon.

[Jack]

Update your thread Jack, want to get my bleed valve fitted tonight.

There are a couple of other threads, with photos.

[the flash]

How much quicker did it feel when you did the mods?

Theres someone on vxon with 117hp and new 200ib of torque not sure if its running nitrous or not, think it was in performance vauxhall in a dyno shoot out.

[Jack]

It's probably Rich C, and IIRC he has a 75bhp+ nitrous kit as well.

It's a lot lot quicker. There's a video somewhere of me doing 25 - 70 and it only takes about 10 seconds.

It's made a very noticeable difference. I've only set mine up roughly cos I don't have a boost gauge, but should be getting one soon so I'll see how far it'll go.

It's definately worth doing though. I need to get mine on a dyno and see how much it's putting out now.

[the flash]

Yer thats the bloke, whats fueling like now mpg etc?

I got 22psi out of a bleedvalve on a td sierra without ic, would be funny to see what the isuzu does. Is it much better than the black top lowblow gm engine i've got?

If only your were close i'd love to have a testdrive

[ANDYRACER]

The vauxhall diesel engine is crap, mine is standard and is boosting at 1 bar for some reason and goes really really well. Coming from a 97bhp nova sri, the cavalier doesnt exactly feel that slow. Plus i love when it comes on boost, puts a nice grin on my face.

[the flash]

I do remember being chased up the DC by something when i had a nova gte years ago, slowed down and a mk3 astra td pushed in front lol i was abit shocked.

[Jack]

I got 22psi out of a bleedvalve on a td sierra without ic, would be funny to see what the isuzu does. Is it much better than the black top lowblow gm engine i've got?

Think the Isuzu can manage 1 bar, so about 14psi?

I haven't noticed a difference in fuel economy. Drive like a granny most of the time, but it's nice to have a bit of go when you need it.

http://www.migweb.co.uk/forums/attac...i?d=1165110520

There's my video.

[the flash]

Speed certainly goes than mine, i like the turbo spool up sound.

[ANDYRACER]

Need to change the gearbox on mine, cant get it past 100mph even tho the engine still wants to pull.
F16 cr maybe on the cards from an 20seh.

[Jack]

F16 cr maybe on the cards from an 20seh.

Why would you want a close ratio gearbox on a diesel?

The gearbox they have, the F18w, is the longest FWD gearbox that Vauxhall do, with the highest final drive.

Mine will do 110mph, but it's so close to the redline you might as well get out and pull the sump plug out as a final insult.

I'm definately planning a longer gearbox for mine, I don't quite know how though. Bigger wheels might be the only way you're going to get a higher top end for a reasonable budget.

I did write a whole thread comparing the different gearboxes and all the ratios and how suitable they would all be for a TD, but then the server crashed and they had to restore from a backup.

[Tathan]

Good thing about tuning a diesel, because a diesel by its nature runs incredibly lean on part throttle openings, you won't lose any economy by increasing output (providing you don't use the extra power available ). In fact, simple stuff like different air filters and less backpressure will actually improve economy.

[Jack]

Good thing about tuning a diesel, because a diesel by its nature runs incredibly lean on part throttle openings

How so? Could you explain, please?

I like diesels, I understand them better.

I'm a bit dense.

[Jack]

I did write a whole thread comparing the different gearboxes and all the ratios and how suitable they would all be for a TD, but then the server crashed and they had to restore from a backup.

Speak of the devil, I've just found the meat and two veg.

Looking at that, an F18w would be the way to go.

[Tathan]

Ummm.... Panics...


Weeeellll, in a petrol you inject fuel and it gets sucked into the cylinder, then valve closes and it compresses the charge which is then ignited.

In a diesel, there is no throttle so the air is drawn in by vacuum and scavenging regardless of how hard you're pressing the pedal. It gets drawn in, compressed mightily, temp increases to 600+ degrees (because it's compressed), then at TDC, fuel is injected incredibly quickly (why diesels run such stupid fuel pressure, 2100BAR on my Skoda ). The fuel immediately ignites due to the temperature.

If the car's idling, the amount of fuel injected is teeny, approx same amount as a bumblebee ejaculation. There's no throttle so very small pumping losses, so it'll sit there and idle using a fraction of the fuel a petrol car would. Likewise at part throttle openings, it only injects a teeny amount. All the fuel is burnt, with plenty of air left over. When you turn up fuel pumps (the classic diesel trick), you're effectively massively overfuelling it at WOT, which does make more power as you're ensuring every little last bit of air is used. This is why you get big black clouds out the back when you do it, and why manufacturers don't send them out the factory like that.

This ignores turbos, that's for tomorrow's lesson

[Tathan]

The lack of throttle makes the engine much more efficient at part openings, a petrol will kick the **** out of it in terms of peak power produced though but at a sacrifice to part openings. AFAIK, a diesel with the same specific output as a petrol is on a par with it for MPG when they're both at WOT. That's not even considering the fact that diesel is a lot denser, and has a higher calorific value.

The Fabia easily drops into single figures (usually 7-8mpg) if you rev it out in 2nd lmao

[Tathan]

Forgot, other reason the fuel pressure is that high, is because you're injecting it into a highly compressed cylinder and if there wasn't a large pressure differential, the diesel wouldn't do feck all lmao

[DutchNovaDiesel]

Looking at that, an F18w would be the way to go.

There are F16W's out there with a 3.55 FDR (and F13W's with a 3.35 )

Calibra gearboxes

[Ed]

Mine will do 110mph, but it's so close to the redline you might as well get out and pull the sump plug out as a final insult.

Really!? What is the redline on it? That must be a short 5th gear?