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Turbo TR6? Yes sir!

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rjtr6 Avatar
rjtr6 Richard Janvier
Quebec, Quebec, Canada   CAN
Hi Doug,

Thank you for your message.
Sorry for your leg. Hope you will be better soon. To answer your question,
we've placed the carb ahead of the turbo to keep simplicity of the system (and reversibility).
As Dick said, I don't want to put the carb in a pressurize box. The constant depression design of this carb
make it a good choice for a draw thru system. It is almost impossible to overcarbureted an engine with this kind of carb
as the slide open in relation with the air demand. The turbo stay relatively cool due the cooling effect of the gasoline in the intake charge. The boost is controled by an external wastegate (The red part on the pictures) that we've set to 7 psi. Next summer I will increase the boost to 10 psi but I'm sure I will need to add water injection between the carb and the turbo to
cool down the intake charge and avoid detonation. But for now, the car is very fun to drive with instant power available under the foot. I use premium fuel at 92 octane. That's the highest rating I can get here. Fortunately, I didn't have detonation yet.
I will post few more pictures soon.
I've read your aircraft stuff with interest and noticed that it is an other world but very exhilarating.

BTW, my son's name is Hubert

Best regards
Richard

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TR6Ken Avatar
TR6Ken Ken U
Loomis, CA, USA   USA
Nicely, nicely done!

rjtr6 Avatar
rjtr6 Richard Janvier
Quebec, Quebec, Canada   CAN
Thank you Ken

There is more to come. As I said, I will post few more pictures this weekend.
Have a good day

Richard

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Punkdogstr6 Doug Lawson
Culver City, California, USA   USA
Richard & Dick,
As you've figured I'm a aircraft engine guy that's trying to follow and learn on the auto turbo systems. Even though the application are completely different the purposes and physics are the same. Aircraft systems are not only for power they compensate for the decrease in air pressure as the planes climbs. They are also used to pressurize the cabin and operate deicing equipment so the systems can get complicated and be a pain to trouble shoot. The primary job of the turbo controller is to maintain the the power setting as the plane climbs or descends without any movement of the throttle control.
This is where I start to loose you guys. The primary power indicator is a manifold pressure gauge. It's calibrated in inches of mercury and is measured after the throttle body. When you guys are talking "psi " and "bars" I'm lost. Also with a car you are constantly moving the throttle so how does the turbo controller work and where are you measuring this " PSI " ?
Our base line for power out put is called " standard day " at sea level that is defined as 29.9 inches of mercury which I believe is 14.7 PSI.
The larger engines I work on are pushing 350 HP out of six air cooled cylinders. Max / take off power is about 42 inches of mercury at 2,700 RPM with a constant spark advance of 20 degrees, 100 octane fuel with most using intercoolers.
When I read you are thinking of running " 10 PSI " with water injection it doesn't seem like much power to me. What am I missing here ?

rjtr6 Avatar
rjtr6 Richard Janvier
Quebec, Quebec, Canada   CAN
Hi Doug,

When we are talking about 7 or 10 psi, it is above the normal air pressure of about 14 psi or 1 bar. As you know, a non-turbo engine (NA) has always vacuum inside the intake except at wide open throttle (WOT). When you add the turbo to an engine you push more air into the combustion chambers. Therefore you must add more fuel to keep the air/fuel ratio in a safe range. The turbo is able to reach a much higher pressure than 10 psi. That's why we use a wastegate to allow the exhaust gas to bypass the turbo when the set point is reached. Of course, there is variation of pressure in the intake along the power curve but it is not suppose to overcome the set point (10 psi for example). So, my TR6 at 7 psi of boost has in fact 21 psi of absolute pressure in the intake. That's pretty close of your 42 inches of mercury at take off and for a 2400lbs car it's pretty much.

Regards
Richard

Punkdogstr6 Doug Lawson
Culver City, California, USA   USA
Got it. Thank you.
The aircraft engines that run 42 inches, they don't last long.
Again, thanks for the lesson.
Doug

sixtynine Avatar
sixtynine mitch somethingorother
las vegas, nv, USA   USA
Have 2 different sets of carbs,
The piston with the 2 notches must be the adjustable, the other the earlier with the ability to swap needles.?
Wondering if i should. use the earlier with the adjustable jet i've seen advertised.
Also thinking about AJ6mod6 comments and the Su 2" carb.



Edited 4 time(s). Last edit at 2014-02-23 01:31 PM by sixtynine.

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Attachments:
IMG_20140223_083847[1].jpg    41.1 KB
IMG_20140223_083847[1].jpg

poolboy Avatar
poolboy Ken D
Sandy Hook, Mississippi, USA   USA
All I can tell you from that picture is that they look like pre 73 carbs.
If I saw the top of the air valve instead of the bottom of the air valve in that picture, I would be able to tell you if they had adjustable needles.

TR6Ken Avatar
TR6Ken Ken U
Loomis, CA, USA   USA
I think the combination of aircraft and TR6 talk is relevant; as this TR6 is going to fly!

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AJ6mod6 Avatar
AJ6mod6 Gareth T
Disabled Account, Antarctica   ATA
1989 Jaguar XJ40 "Animal2"
In reply to # 927530 by rjtr6 When you add the turbo to an engine you push more air into the combustion chambers. Therefore you must add more fuel to keep the air/fuel ratio in a safe range.

So, my TR6 at 7 psi of boost has in fact 21 psi of absolute pressure in the intake. That's pretty close of your 42 inches of mercury at take off and for a 2400lbs car it's pretty much.

This is incorrect.
Aero engines don't have massive long strokes and non optimal valving.
They don't work in the same way in terms of volumetric efficiency so they make a massive amount higher torque per litre of engine.

This idea that the intake pressure translates into cylinder pressure can easily be verified on an engine dyno, and it's demonstrably false.

You can measure the cylinder pressure with piezo devices and it's typically of the order of 50-60BAR.
You will find it is no different from a reasonably well tuned N/A engine but the turbo will have a narrower power band due to the need for much milder cam timing (to prevent charge loss).

In fact I doubt very much if you have even changed from the very mild low lift USA camshaft profile.
This cam is only 10-50 timing (240 degrees) and very little lift.

Boost and flow are TWO totally different problems.

Your inlet valve is incable of flowing more than 70cfm at 10" ( 108 at 25" ) , but this is at 0.450" lift.
Your engine with a milder cam and less valve lift, will flow AT LEAST 30% less than this.

It simply doesn't matter if you put 200psi at one end you will not get an ounce more cylinder filling.It's like blowing hard into a drinking straw, and on top of this a single CD carb has a very finite flow level, with extremely poor droplet size when it's wide open.

Most people simply don't get this relationship between boost pressure, cylinder filling and droplet size.
Droplet size is what determines the limit of A/F ratio v CR and the onset of detonation.

The CD carb is about the worst possible solution imagineable for this, and it will CAUSE detonation merely by the fact it is generating bucket loads of unburnt fuel, dead spots and huge droplets.
You could do instantly a lot better merely by fitting a large Solex, Weber or Dellorto.

This is why your engine is incapable of making more than about 300-330cfm TOTAL while the rest of the turbo system just backs up the boost and generates more heat.

If you are lucky you could get an absolute maximum of about 160bhp at best, but more likely around 135-140.....
(Easily matched or exceeded by a N/A EU TR5 engine on just 2 SUs or 3 webers with a good head and exhaust)

If you increase the boost pressure (as you call it) in fact you will get LESS power, not more, because the extra heat will push the charge temperature off the scale and the head will in any case not flow any more air.

This is why the only way to get BIG power out of such an engine is to reduce the stroke, and increase the head flow.
De-stroking it simply increases the VE and the chamber is much smaller, helping combustion.

INCREASE THE FLOW, not the PRESSURE and throw the Stromberg in the bin.



Edited 4 time(s). Last edit at 2014-02-23 06:09 AM by AJ6mod6.

rjtr6 Avatar
rjtr6 Richard Janvier
Quebec, Quebec, Canada   CAN
Hello everybody

Gareth is right!!!

It is not possible to get much more flow from the cylinder head of a TR6 and the crank is way too large for high revolution. As a result the VE is not good. Moreover, the US spec camshaft is milder than mild. When I was talking about pressure, it was to explain the meaning of psi value to another member. I talked about intake pressure not combustion chamber because the head is like a very restritive funnel. Also, the carb I used is not the best one. That's why I kept the size small to have a higher velocity near the jet area to get the smallest possible droplets in the inlet tract.

Gareth, I've read your book with great interest. It represents a huge amount of work to test all the modifications you did. Maybe later I'll try to apply what you describe in your book to a more 'ideal' engine.

My goal was not to build a high power engine but to mildly modify my TR6 engine with the smallest budget I can. It cost me less than $600 CDN to build this set up and I have what I want: More torque through the rev range. Maybe it is equal to a PI engine but it doesn't matter to me. At 8psi, the car is more fun to drive all around and it is rewarding to see the surprise in the face of modern sports cars drivers when the old TR6 accelerates.

Best to all
Richard

AJ6mod6 Avatar
AJ6mod6 Gareth T
Disabled Account, Antarctica   ATA
1989 Jaguar XJ40 "Animal2"
In reply to # 940377 by rjtr6 It is not possible to get much more flow from the cylinder head of a TR6
Moreover, the US spec camshaft is milder than mild.

At 8psi, the car is more fun to drive all around and it is rewarding to see the surprise in the face of modern sports cars drivers when the old TR6 accelerates.
Actually you are wrong here.
You can quite easily get a good 20% more flow out of the TR6 head.
The increase in exhaust port efficiency you can get is even better, which is what you really need to get the thing to breath.

Also I do still have a camshaft profile ideally suited to a forced induction engine that was originally developed for a cross flow turbo 1600 engine.
This gives similarly period to the mild US cam but about 3mm (0.120"winking smiley more lift.

With this kit you could get the turbo to kick in properly as low as 2500rpm and not run out of puff until 5000rpm+

The original twin outlet cast iron TR6 exhaust manifold is well able to cope with a throughput at least 50% more than the standard US motor puts out, and the original twin silencer starts to throttle things down from about 145bhp up, so that's easily changed too.

If you really want to get some more GO from your T3 turbo, stick a 2" HD8 Jaguar carb on there from an early XJ6.
That should be a minimum for such an installation and they are dirt cheap.

If you do all that, and flow out the inlet manifold so it doesn't have those terrible restrictions for No 2 and No 5 cylinders you could get the thing to go REALLY well.

It will also take more advance.
You won't get any power at 16 degrees, you are going to need at least 22.

The Garrett T3/T34 is a good turbo and very reliable in operation, which is why Renault, Ford, Peugeot and many others used it on their cooking production motors.

They were made only a few miles away from me in France, when I was working in that region, but not many people know they are made in that factory in the Vosges.

rjtr6 Avatar
rjtr6 Richard Janvier
Quebec, Quebec, Canada   CAN
Thank you Gareth for your advice

I was reffering to the TR6 head in stock form with only a free flow exhaust and when I said milder than mild about the camshaft I meant for NA engine. It is one reason why I opted for a turbo set up. I didn't want to change camshaft and/or head. I'm a bit afraid to do porting. I don't have much experience in that area. It seems to me that it is quite easy to ruin a cylinder head.

But now, I'm very interested by what you said about the camshaft. Is it available somewhere? What is the name/number of this part.
I looked for a HD8 carb initially but here it is more difficult to find and unfortunately it is not dirt cheap.

I have a spare TR6 head on my bench. I will read your book another time and maybe I'll make a try into porting.

Until then, thank you again

Richard

PS: If you worked in France, do you speak french?

AJ6mod6 Avatar
AJ6mod6 Gareth T
Disabled Account, Antarctica   ATA
1989 Jaguar XJ40 "Animal2"
In reply to # 940464 by rjtr6 I was reffering to the TR6 head in stock form with only a free flow exhaust and when I said milder than mild about the camshaft I meant for NA engine.

But now, I'm very interested by what you said about the camshaft. Is it available somewhere?

I looked for a HD8 carb initially but here it is more difficult to find and unfortunately it is not dirt cheap.

PS: If you worked in France, do you speak french?
I was in France for many years.

The HD8 is a dead easy carb to find in the UK, you just go to a breaker that does Jags and go find a manifold off some early XJ6 4.2L (the one with the manual choke adjustment).

The camshaft I will have mastered in the next few weeks, because I have had it (4cyl version) in stock for 20+ years.
This means I can grind that profile onto a brand new 6 cyl cam blank

As far as I know it's the ONLY camshaft profile that has ever been made for the pushrod turbo or s-charged engine.
Even Jaguar never engineered or redesigned their camshafts properly from the N/A to S-charged versions, so I would be curious to see what it would do to a TR6-T.

The lobes are really quite triangular in shape so it has nigh on ZILCH overlap but quite a bit of lift and very sharp ramps, which is exactly what any decent forced induction engine needs.


Attachments:
turbo_cam.jpg    5.8 KB
turbo_cam.jpg

sixtynine Avatar
sixtynine mitch somethingorother
las vegas, nv, USA   USA
I'll take your advice. If anyone has a suitable carb postup or pm me.

In reply to # 940368 by AJ6mod6
In reply to # 927530 by rjtr6 When you add the turbo to an engine you push more air into the combustion chambers. Therefore you must add more fuel to keep the air/fuel ratio in a safe range.

So, my TR6 at 7 psi of boost has in fact 21 psi of absolute pressure in the intake. That's pretty close of your 42 inches of mercury at take off and for a 2400lbs car it's pretty much.

This is incorrect.
Aero engines don't have massive long strokes and non optimal valving.
They don't work in the same way in terms of volumetric efficiency so they make a massive amount higher torque per litre of engine.

This idea that the intake pressure translates into cylinder pressure can easily be verified on an engine dyno, and it's demonstrably false.

You can measure the cylinder pressure with piezo devices and it's typically of the order of 50-60BAR.
You will find it is no different from a reasonably well tuned N/A engine but the turbo will have a narrower power band due to the need for much milder cam timing (to prevent charge loss).

In fact I doubt very much if you have even changed from the very mild low lift USA camshaft profile.
This cam is only 10-50 timing (240 degrees) and very little lift.

Boost and flow are TWO totally different problems.

Your inlet valve is incable of flowing more than 70cfm at 10" ( 108 at 25" ) , but this is at 0.450" lift.
Your engine with a milder cam and less valve lift, will flow AT LEAST 30% less than this.

It simply doesn't matter if you put 200psi at one end you will not get an ounce more cylinder filling.It's like blowing hard into a drinking straw, and on top of this a single CD carb has a very finite flow level, with extremely poor droplet size when it's wide open.

Most people simply don't get this relationship between boost pressure, cylinder filling and droplet size.
Droplet size is what determines the limit of A/F ratio v CR and the onset of detonation.

The CD carb is about the worst possible solution imagineable for this, and it will CAUSE detonation merely by the fact it is generating bucket loads of unburnt fuel, dead spots and huge droplets.
You could do instantly a lot better merely by fitting a large Solex, Weber or Dellorto.

This is why your engine is incapable of making more than about 300-330cfm TOTAL while the rest of the turbo system just backs up the boost and generates more heat.

If you are lucky you could get an absolute maximum of about 160bhp at best, but more likely around 135-140.....
(Easily matched or exceeded by a N/A EU TR5 engine on just 2 SUs or 3 webers with a good head and exhaust)

If you increase the boost pressure (as you call it) in fact you will get LESS power, not more, because the extra heat will push the charge temperature off the scale and the head will in any case not flow any more air.

This is why the only way to get BIG power out of such an engine is to reduce the stroke, and increase the head flow.
De-stroking it simply increases the VE and the chamber is much smaller, helping combustion.

INCREASE THE FLOW, not the PRESSURE and throw the Stromberg in the bin.

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