High Compression DJ pistons.

1

As many of you will know, VW marketed two versions of the 2.1 petrol engine, the MV and the DJ.


The DJ was a high-compression motor which, as far as I know, was not offered for sale in Australia.

There does not appear to be any difference in the bottom end, but I suspect that they used the larger air-flow meter off the old 1.9 motor.

The DJ ran a 10.5:1 compression ratio and developed 112 BHP at 4800 rpm, and 128 lb.ft. of torque at 2800 rpm, compared to 95 and 118 at the same revs in the MV.

These pistons have not been available for sale for some time, but I have tracked down a possible source.

Has anyone out there used these pistons? Did they have any issues with overheating or pinking on the pigswill they call petrol in Australia? Do they require 98 octane fuel, or do they run OK on 95?

Has anyone run the 1.9 AFM on the 2.1? Are they compatible with the MV efi system, or do you need to transplant the entire engine management system from a 1.9 T3 with the DJ system?

I once had a standard 1.9 Caravelle and it went like a scalded cat.

Would appreciate some advice, as the opportunity cannot be ignored.

Roger B. 


2
Roger I've got a DH Caravelle DJ SA Micro and a few MVs and I must say the DH is surprisingly nimble the DJ free revs like a hot Manx . Think the gearbox was changed after the DH but not sure if the ratios were part of the upgrade but could explain the nimble performance of something that is supposed to be compromised by low figures.
Not sure about the compatibility of the AFM.
I would guess the cam part numbers might be different ?
Could be worth checking ETKA ? to see if this is the case?
My DJ and my DH does not have a cat ?
Cheers

On Sat, Dec 5, 2015 at 10:23 PM, gullyraker53@gmail.com [Syncro_T3_Australia] <Syncro_T3_Australia@yahoogroups.com> wrote:

As many of you will know, VW marketed two versions of the 2.1 petrol engine, the MV and the DJ.


The DJ was a high-compression motor which, as far as I know, was not offered for sale in Australia.

There does not appear to be any difference in the bottom end, but I suspect that they used the larger air-flow meter off the old 1.9 motor.

The DJ ran a 10.5:1 compression ratio and developed 112 BHP at 4800 rpm, and 128 lb.ft. of torque at 2800 rpm, compared to 95 and 118 at the same revs in the MV.

These pistons have not been available for sale for some time, but I have tracked down a possible source.

Has anyone out there used these pistons? Did they have any issues with overheating or pinking on the pigswill they call petrol in Australia? Do they require 98 octane fuel, or do they run OK on 95?

Has anyone run the 1.9 AFM on the 2.1? Are they compatible with the MV efi system, or do you need to transplant the entire engine management system from a 1.9 T3 with the DJ system?

I once had a standard 1.9 Caravelle and it went like a scalded cat.

Would appreciate some advice, as the opportunity cannot be ignored.

Roger B.



3

Roger,

The MV does not have a knock sensor.  Perhaps VAG decided that our local pig swill would prevent the engine from ever knocking or perhaps they were saving money – who knows? 

Les

From: Syncro_T3_Australia@yahoogroups.com [mailto: Syncro_T3_Australia@yahoogroups.com ]
Sent: 05 December 2015 23:24
To: Syncro_T3_Australia@yahoogroups.com
Subject: [Syncro_T3_Australia] High Compression DJ pistons.

As many of you will know, VW marketed two versions of the 2.1 petrol engine, the MV and the DJ.

The DJ was a high-compression motor which, as far as I know, was not offered for sale in Australia .

Would appreciate some advice, as the opportunity cannot be ignored.

 

Roger B. 

 

 

4
Peter, pleased to hear that you have personal experience with the DJ engines.

Do they run hotter than the MV engines? Have you ever had any overheating problems with them?

Do they run OK on 95RON fuel or do they prefer 98?

I found an old T3 sales brochure printed in Germany in August 1988 for the Australian dealer network. Here is an excerpt;

"Those who set very high standards where performance and traction are concerned will find the 2.1 litre fuel injection engine developing 82 Kw (112 bhp) (premium grade 4 star fuel) the most interesting option. It has a digitally-controlled fuel-injection (Digijet), is immensely free-revving and is fitted with a five speed gearbox as standard.

One option highly recommended from an ecological point of view is the above engine operating in conjunction with a catalytic convertor and lambda probe, and developing 70 Kw (95 bhp). This version runs on unleaded fuel."

This makes it pretty clear that the DJ engine used the earlier Digijet engine management system, and lacked a catalytic converter.

I suspect that the camshaft and valve sizes might be identical on both engines, as maximum power and torque are developed at exactly the same engine speed. Will have to delve a little bit further to find out though.

It could well be that the high compression pistons will make a noticeable improvement to power and torque, even with the Digifant engine management system and cat as fitted to our MV engines.

I have already sourced a new stock genuine camshaft, and am tossing up between a 2.2 liter GoWesty big bore kit or the high-compression pistons for my next rebuild.

I am searching for a moderate increase in power without detracting the tractable nature of the stock engine.

Any thoughts?

Roger B.


5
Roger, the internals of a DJ are identical to the MV other than the pistons. The cams are the same and a new genuine cam is a good way to go if you want low end torque and reliability. I would use  highest octane fuel possible. There are benefits (including fuel economy) to using 95+ octane when your static compression is upwards of 9:1. I would not touch gowesty pistons. There lack of compression and high oil consumption reports put me off. I you can get your hands on Dj pistons at reasonable price go for it. The digifant will cope fine with dj pistons as will the cooling system which is identical. A cat conv will make next to no difference also. If you want to make more power there are lots of things you can do. Digifant an digijet are very basic efi systems and leave a lot of power on the table that could be tapped by an after market system. Gregor

From: "Roger Bayley gullyraker53@gmail.com [Syncro_T3_Australia]" <Syncro_T3_Australia@yahoogroups.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Monday, 7 December 2015, 0:10
Subject: [Syncro_T3_Australia] Re: High Compression DJ pistons.

 
Peter, pleased to hear that you have personal experience with the DJ engines.

Do they run hotter than the MV engines? Have you ever had any overheating problems with them?

Do they run OK on 95RON fuel or do they prefer 98?

I found an old T3 sales brochure printed in Germany in August 1988 for the Australian dealer network. Here is an excerpt;

"Those who set very high standards where performance and traction are concerned will find the 2.1 litre fuel injection engine developing 82 Kw (112 bhp) (premium grade 4 star fuel) the most interesting option. It has a digitally-controlled fuel-injection (Digijet), is immensely free-revving and is fitted with a five speed gearbox as standard.

  One option highly recommended from an ecological point of view is the above engine operating in conjunction with a catalytic convertor and lambda probe, and developing 70 Kw (95 bhp). This version runs on unleaded fuel."

This makes it pretty clear that the DJ engine used the earlier Digijet engine management system, and lacked a catalytic converter.

I suspect that the camshaft and valve sizes might be identical on both engines, as maximum power and torque are developed at exactly the same engine speed. Will have to delve a little bit further to find out though.

It could well be that the high compression pistons will make a noticeable improvement to power and torque, even with the Digifant engine management system and cat as fitted to our MV engines.

I have already sourced a new stock genuine camshaft, and am tossing up between a 2.2 liter GoWesty big bore kit or the high-compression pistons for my next rebuild.

I am searching for a moderate increase in power without detracting the tractable nature of the stock engine. 

Any thoughts?

Roger B.




6
Hi Roger, I have DJ pistons in my engine and they do work well with the stock EFI. No overheating problems and I run on gas most of the time. I do notice oil pressure drop when going hard on hot days but only really noticeable when running on gas. Also have an oil cooler for added protection. From past experience I would advise you to ditch the rings that come with the set and go for the Grant rings that van cafe are selling. Hope this helps, Eddie.
7
Thanks Greg and Eddie for your valuable insights. Makes it worthwhile to be a member of this erstwhile group!
Will chase up the DJ pistons.

I have a set of Spanish cylinder heads, which most people claim are better than the original kit, except that the valves need to be replaced with better quality units.

I have used these heads on three engines that have done high mileage with no problems, but have dismantled one engine that has had a different exhaust valve fitted - indicating a problem there in the past.

So I am inclined to spend the money on quality valves, just to make sure, on the "do it once and do it right" principle.

Does anyone know of a local source of high-quality valves?

Has anyone out there heard of any weakness in the Spanish valve collets or associated hardware?

Cheers, Roger B.
8
The valves and collets are a problem, particularly the exhaust valves. I think they have now fixed their collets. The problem was that they where more than 180 degrees each so they touched on both sides and this would not allow the collet to tighten onto the valve. A quick grind or use the old ones. The exh valves are just rubbish. The seat cut did not allow a large enough contact area which prevents the valve from dissipating heat. When your head guy fits the valves he will do a 3 angle cut and fix that. You are looking for TRW branded valves. US suppliers are probably easier than local. 
As a side note the genuine vw heads are not the evil people make them out to be. If badly overheated they will crack at a manufacturing date stamp near the plug holes. The amc's are thicker and don't have the stamp. That is about the only way they are better in my opinion and at the end of the day if you don't overheat them where is the issue? Gregor

From: "Roger Bayley gullyraker53@gmail.com [Syncro_T3_Australia]" <Syncro_T3_Australia@yahoogroups.com>
To: Syncro_T3_Australia@yahoogroups.com
Sent: Tuesday, 8 December 2015, 16:18
Subject: [Syncro_T3_Australia] Re: High Compression DJ pistons.

 
Thanks Greg and Eddie for your valuable insights. Makes it worthwhile to be a member of this erstwhile group!
Will chase up the DJ pistons.

I have a set of Spanish cylinder heads, which most people claim are better than the original kit, except that the valves need to be replaced with better quality units.

I have used these heads on three engines that have done high mileage with no problems, but have dismantled one engine that has had a different exhaust valve fitted - indicating a problem there in the past.

So I am inclined to spend the money on quality valves, just to make sure, on the "do it once and do it right" principle.

Does anyone know of a local source of high-quality valves?

Has anyone out there heard of any weakness in the Spanish valve collets or associated hardware?

Cheers, Roger B. 


9
Great advice Greg, thanks for that.

Roger.