12H-T performance Build (2 Viewers)

[Dougal]

Yeah, it shows how important it is to reduce parasitic losses. It would be interesting to know idle fuel consumption on various vehicles.

If I can get lowish EGT's and huge torque at ~ 1600rpm, I will be very happy since that should equate to a good bsfc result. I should aim for the 1.9 TDi EGT curve.

I did consider destroking my engine at one stage..... I just cant make up my mind. Maximize the potential capacity or make it less. I wont know what I want to do for sure until I get the twin turbo running!

You can get a 7psi back pulse in the exhaust, so in effect you can supercharge it in the resonance range - to good effect!

Idle fuel consumption on the VW 2.0tdi is 0.9 litres per hour according to the computer. This is with the AC running. That's the only result I have right now.

The higher your EGT's are, they higher efficiency you'll get from both combustion and from the turbocharger. After all the goal is to expand air. So attempting low EGT's by pumping extra air will cost you in fuel economy and power/torque.
Just pick a level that you consider safe for your engine and use that. I run 750C peak, for continuous loads (long hills) I keep it around 650C. The occasional excursion over 800C too :whoops: but it seems to survive fine.

 

[gbentink]

Dougal, do you get much smoke at those temps, they are racing high and your top rings will wear really fast with the overfueling. Personally I think there is a limit to what you are saying being true. It is a balance against parasitic friction, pumping and heat losses for the most part. So in some instances it is true, but not all. I would include the turbo in pumping losses.

Fitting an intercooler will make your turbo work better with the increased mass flow and the egt's will be less. So, its not all about the egt's.

I get the head back today. To race cut the valves/seats, change springs, increase valve seat pressure 20%, full recon + resizing conrods and fitting little end bushes cost me a whopping AUD $1750 (I supplied the valves, seats and did 40 hours of porting/valve deshrouding). This is getting to be an expensive hobby!

I will post some photos tomorrow hopefully! I need to hear some "man that head looks awesome" comments to make me feel better


This is rather more than I budgeted for the excercise. Oh well, I will send in the photos

 

[Dougal]

Dougal, do you get much smoke at those temps, they are racing high and your top rings will wear really fast with the overfueling. Personally I think there is a limit to what you are saying being true. It is a balance against parasitic friction, pumping and heat losses for the most part. So in some instances it is true, but not all. I would include the turbo in pumping losses.

Fitting an intercooler will make your turbo work better with the increased mass flow and the egt's will be less. So, its not all about the egt's.

I get the head back today. To race cut the valves/seats, change springs, increase valve seat pressure 20%, full recon + resizing conrods and fitting little end bushes cost me a whopping AUD $1750 (I supplied the valves, seats and did 40 hours of porting/valve deshrouding). This is getting to be an expensive hobby!

I will post some photos tomorrow hopefully! I need to hear some "man that head looks awesome" comments to make me feel better


This is rather more than I budgeted for the excercise. Oh well, I will send in the photos

I only get smoke at altitude or if it's had a succession of cold starts. The rest of the time it burns clean.
I've been running on this tune for the last 18 months and haven't had any related problems yet. I'm well aware of the stress I'm putting everything under and will have no qualms about shouting it a piston/liner kit if needed.

Part of the reason for my high EGT's is the lack of an intercooler, I'm feeding my engine air at over 135 deg C. The air volume I'm pushing could be easily beaten by 13 psi with a good intercooler or 15psi with an average one.
So while the temps are high, the AF ratios seem to be still clear of the smoke zone (unless at altitude).
The turbos are built to take that temp (exhaust housing may crack, many of them do) and a good source of info tells me 750C is mentioned in isuzu literature as the maximum exhaust temp allowed.

Here's a couple of diesel BSFC maps (these are hard to find, if you've got more I'd love a copy). They all have the same basic shape with max efficiency at high load and near max torque.
However, peak BSFC doesn't matter as much as how widely spread you can get good BSFC.

 

[gbentink]

Thanks for posting that. I have only seen one a few times, they really are hard to find. The VW is just so impressive over such a wide operating area. Peak torque also equals peak efficiency, clearly and BSFC is highest at full load at all rpms except at the low end (expected).

By the way, I had a look at the inline pump on the weekend. I was thinking that the pump could be modified to have the idle circuit and rev limit removed and be simply a rack controlled torque….. If connected to a stepper motor and ECU control, you could map boost and torque! In the 12HT, it has a throttle shutoff, so you could have a cabin safety cutoff…. Possible a dumb idea, but on the face of it, other than the danger of an over rev, seems like a good one.

 

[Dougal]

Thanks for posting that. I have only seen one a few times, they really are hard to find. The VW is just so impressive over such a wide operating area. Peak torque also equals peak efficiency, clearly and BSFC is highest at full load at all rpms except at the low end (expected).

By the way, I had a look at the inline pump on the weekend. I was thinking that the pump could be modified to have the idle circuit and rev limit removed and be simply a rack controlled torque….. If connected to a stepper motor and ECU control, you could map boost and torque! In the 12HT, it has a throttle shutoff, so you could have a cabin safety cutoff…. Possible a dumb idea, but on the face of it, other than the danger of an over rev, seems like a good one.

You mean BSFC is lowest? Efficiency highest?

I'm currently playing with stepper motors trying to get a home-built cnc mill running. So right now I couldn't think of anything worse. But ask me again when it's running.

How about an indicator on the rack which shows inside the cab how much fuel you're currently injecting?

 

[gbentink]

Thanks for posting that. I have only seen one a few times, they really are hard to find. The VW is just so impressive over such a wide operating area. Peak torque also equals peak efficiency, clearly and BSFC is highest at full load at all rpms except at the low end (expected).

I wasnt at all worried about your turbo. Good power figures though for a non intercooled quite heavily boosted engine.

By the way, I had a look at the inline pump on the weekend. I was thinking that the pump could be modified to have the idle circuit and rev limit removed and be simply a rack controlled torque….. If connected to a stepper motor and ECU control, you could map boost and torque! In the 12HT, it has a throttle shutoff, so you could have a cabin safety cutoff…. Possible a dumb idea, but on the face of it, other than the danger of an over rev, seems like a good one.

 

[gbentink]

Thanks for posting that. I have only seen one a few times, they really are hard to find. The VW is just so impressive over such a wide operating area. Peak torque also equals peak efficiency, clearly and BSFC is highest at full load at all rpms except at the low end (expected).

I wasnt at all worried about your turbo. Good power figures though for a non intercooled quite heavily boosted engine.

By the way, I had a look at the inline pump on the weekend. I was thinking that the pump could be modified to have the idle circuit and rev limit removed and be simply a rack controlled torque….. If connected to a stepper motor and ECU control, you could map boost and torque! In the 12HT, it has a throttle shutoff, so you could have a cabin safety cutoff…. Possible a dumb idea, but on the face of it, other than the danger of an over rev, seems like a good one.

 

[gbentink]

Well, got my head. Forgot to take photos. Looks great, perfect job. Seating pressure on valves has been increased from 70lb's to 100lb's to eliminate valve float under heavy boost. Many mods done and has all worked out great.

Dougal, how much boost would you estimate is required to make 600nm? I have my own calcs but was wondering how much you would expect?

I also picked up a set of pistons and rings yesterday for the next project - 4.9 Stroker 12H-T. But that will be another story! Doing this project has allowed me to measure everything for a fully custom engine next time. I know I am getting ahead of myself, but, its fun!

 

[Dougal]

Well, got my head. Forgot to take photos. Looks great, perfect job. Seating pressure on valves has been increased from 70lb's to 100lb's to eliminate valve float under heavy boost. Many mods done and has all worked out great.

Dougal, how much boost would you estimate is required to make 600nm? I have my own calcs but was wondering how much you would expect?

I also picked up a set of pistons and rings yesterday for the next project - 4.9 Stroker 12H-T. But that will be another story! Doing this project has allowed me to measure everything for a fully custom engine next time. I know I am getting ahead of myself, but, its fun!

So 100lb being the closed force, what's the projected area (i.e. what boost pressure will blow them open)?

600Nm on 4 litres with BSFC of 238, VE 80%, 60% efficent compressor, 60% effective intercooler, sealevel etc
34psi.

Your VV turbo might do that alone.

 

[gbentink]

So 100lb being the closed force, what's the projected area (i.e. what boost pressure will blow them open)?

600Nm on 4 litres with BSFC of 238, VE 80%, 60% efficent compressor, 60% effective intercooler, sealevel etc
34psi.

Your VV turbo might do that alone


Thanks for that. 70lb is stock, so I increased 30lb. The valve is 43.5mm so the extra 30lb gives me 13psi more room than whatever the stock value is. I am happy with that - otherwise it gets really hard on the valve train. The valve float is caused by the pressure across the valve, so I am taking the middle ground; having no idea what the in cylinder pressures are at a given moment!

I started a spreadsheet to do the full turbo calc, but it got quite complicated. I can understand easily enough the impact of the intercooler, but have found it rather more difficult to calculated the heating value of the compressor inefficiency.

When you consider 60% efficiency for the compressor, are you determining the work being done for compressing the air mass to a given pressure and allowing for 66% of the required energy for work to heat the air, factoring that the intercooler then removes 60% of that energy (as K?) and then using the resultant temp to determine density and ultimately CFM?

The other factor is that even if the compressor is perfect, there is heat associated with compression, so the intercooler is removing two sources of heat (other than radiant and convection heating from the engine itself)

I would be interested in how the units finally cancel out to a simple formulae. I know we discussed this a few posts earlier but I was wondering the thought process you used.

If I can get my setup correct, I should be in the plus 70% efficiency for both turbos.

As for the VNT able to do the CFM's, it could probably do a 3.3PR (with some overspeed) up to 2200rpm. If I high flowed it with a 19T compressor wheel, it could flow 530cfm at PR2.8. I did consider it, even for simplicity sake - I was thinking about this very thing this morning. I will run some more calcs.

 

[Dougal]

Thanks for that. 70lb is stock, so I increased 30lb. The valve is 43.5mm so the extra 30lb gives me 13psi more room than whatever the stock value is. I am happy with that - otherwise it gets really hard on the valve train. The valve float is caused by the pressure across the valve, so I am taking the middle ground; having no idea what the in cylinder pressures are at a given moment!

I started a spreadsheet to do the full turbo calc, but it got quite complicated. I can understand easily enough the impact of the intercooler, but have found it rather more difficult to calculated the heating value of the compressor inefficiency.

When you consider 60% efficiency for the compressor, are you determining the work being done for compressing the air mass to a given pressure and allowing for 66% of the required energy for work to heat the air, factoring that the intercooler then removes 60% of that energy (as K?) and then using the resultant temp to determine density and ultimately CFM?

The other factor is that even if the compressor is perfect, there is heat associated with compression, so the intercooler is removing two sources of heat (other than radiant and convection heating from the engine itself)

I would be interested in how the units finally cancel out to a simple formulae. I know we discussed this a few posts earlier but I was wondering the thought process you used.

If I can get my setup correct, I should be in the plus 70% efficiency for both turbos.

As for the VNT able to do the CFM's, it could probably do a 3.3PR (with some overspeed) up to 2200rpm. If I high flowed it with a 19T compressor wheel, it could flow 530cfm at PR2.8. I did consider it, even for simplicity sake - I was thinking about this very thing this morning. I will run some more calcs.

The basics for turbo calcs is adiabatic compression. The temp rise for that is PR^1.4
So multiply your absolute inlet temp (in kelvin) by PR^1.4 and you get the adiabatic outlet temp.
This is for a 100% efficient compressor.
Take the inlet temp from the adiabatic outlet temp and you've got the temp rise across the turbo.
Divide that by your compressor efficiency and you've got the actual temp rise.
Add the actual temp rise to the inlet temp and that's your outlet temp.

Apply the ideal gas law at the outlet to find the density at that temp.

So yeah it's not a simple formula, but a combination of several. I have spreadsheets set up for all this now, makes it easy but I had some brain fade setting them up.

 

[marting]

What's going on here? This thread died before it got really exiting How's it going on this project ?

Will the 300 hp 600Nm 12ht-monster soon be a reality?

 

[gbentink]

Hi Marting,

Just slow going on my side. Wife has been ill, many home maintenance issues to contend with and trying to finish the last bits on the HJ61 before sale - amazing how long everything takes. The engine is (and has been for ages) all machined up ready for assembly, but looks like I have sold the engine to a friend of mine and will rebuild my second 12H-T as a 4.93 litre stroker....

I didnt plan it that way, but there you go. A bit unexpected.....

This also means another ported cylinder head - not looking forward to that as it was very time consuming.

If I end up building the stroker instead of stock displacement, I will start off straight away with the GT3782VA that I have. I have wanted to use this for ages (been on the shelf for 3 years,....) My brother used it to impressive effect on his td42 which made >20psi by 2000rpm, so with 4.93l that equates to in theory ~ 1700rpm. If it doesnt build boost early enough I will go for the twin turbo setup since I have it already. Project includes using the "Suprastick" ecu transmission control on my electronic A442F transmission.


Either way, I will be shooting for more than 200rwhp out of a 12H-T with no smoke to speak of and great drivability.

I have all the stainless fittings and tubing and a new DC/AC Tig waiting to be used for the Twin Turbo project, so will see what happens!!

I need a auto from a HJ61....anyone have one in Perth (or Australia?) No-Go is fine, I mostly need the bellhousing

 

[Tapage]

did you have a website for suprastick ecu .. ? ( I was only able to find some supra info )

 

[gbentink]

Hi Tapage,

SSv4 is the website.

I havent used one, but need to for my conversion. By all accounts I have read they drive as stock when set up correctly. I have read the setup manual - not difficlut at all.

Hope that helps.

 

[gbentink]

Well, things are moving closer....

I have to sell my HJ61 in order to clear the garage for the 12HT conversion in my FZJ80 1997. I need to fix the HJ61 in order to make that happen.

So, I removed the head off the HJ61 and pulled all the pistons. All pistons were perfect condition except for the classic top ring land damage. Mine had done 320,000km so I expected to see it.

In the process of mildly porting the exhaust ports on the head and will have it back on in about 2 weeks.

The history was that the engine blew heaps of smoke (oil) and the reason as it turns out was a stuck oil ring on #6 and generally glazed bores. Virtually no cylinder lip, pistons were not worn either. So, fitting new updated design pistons, new big ends and mildly ported and recond head.

When all running, the next step is to increase boost and fiddle with the injector pump to see what it is capable of. This important leading up to my big build engine - the 4.9 Litre. I really need to find the pump limits.

As for compound turbo or not - still a distinct possibility however the date is pushed out.

I am sure there are many that would be interested in a 4.9 Litre 12H-T? Surely?

 

[blis]

The 12h-t injection pump has 9mm elements in it and in stock form it gives around 110cc/1000 strokes, which should be good for over 200hp easily, with std parts you should be able to get around 160-180hp just by turning up the fuel and boost....

The biggest problem in 12h-t lies in the clutch since it doesnt hold when torque goes above 600nm...

 

[Dougal]

The 12h-t injection pump has 9mm elements in it and in stock form it gives around 110cc/1000 strokes, which should be good for over 200hp easily, with std parts you should be able to get around 160-180hp just by turning up the fuel and boost....

The biggest problem in 12h-t lies in the clutch since it doesnt hold when torque goes above 600nm...

110cc/1000 shots on a 6 cyl at 240 g/kwh is approx 670Nm.
That gives you almost 200hp at 2000rpm.

I figure you'll need about 42psi to make it burn clean, maybe more to keep the EGT's down as even with 60% intercooling you'll be feeding the engine 110C air.

 

[jb BJ73]

"I am sure there are many that would be interested in a 4.9 Litre 12H-T? Surely?"

hell yeah! i'm interested. i got one in the shed waiting to be rebuilt and put in my bj73 when i get the money/time, and i don't want to rebuild it stock.

 

[R2HKS]

I am sure there are many that would be interested in a 4.9 Litre 12H-T? Surely?

Raises hand!!!