Supercharger for TR

[Lebro]

Correct, probably a typo from Peter 

[Peter Cobbold]

4 hours ago, Z320 said:

Peter,

back from my workshop you make me struggle:

HS6 is 1 6/8“ (1.75“), HS8 is 1 8/8“ (2“)?

Yes that is correct. I made a msitake but could not go back and alter it.

 

[Peter Cobbold]

13 hours ago, BlueTR3A-5EKT said:

I was told they lost supply of a vital part.   

I think it was the Holley carb, and for some reason they did not want to use an SU.

[Peter Cobbold]

5 hours ago, Z320 said:

Hi Peter,

thank you for joinig here at this thread and your HS6 evaluation.

This will safe me a lot of money and allows to rotate the SC down instead to hold it leveled for 2 HS6.

But - 2 HS6 will look very impressive?

And yes, the valves have to be out, these butterflys are only used in this case to hold all parts together.

The Moss inlet manifold will not fit the SLK SC because it has a much shorter shaft. --> I have to place it more forward.

The SC's weight is 8.5 kg and it I will not only fix it on the manifold and cylinder head studs.

Also Moss fixes it much solid on the front end of the shaft on the engine.

Allard's book you already recommended me and I own it already for some years.

But it is no fun for me reading it, your seminar dokumentation helps me more, thank you.

Next is to slow down and collect ideas.

Ciao, Marco

 

 

Marco, The first thing to assess is the compression ratio and the fuel octane you can use. That dictates the boost you can use without detonation and that dictates the blower/crank rpm relationship.  There are tricks to reducing detonation. But its best not to be too greedy with boost. Peter

[dblenk]

On 3/11/2023 at 5:52 PM, Z320 said:

Hi Peter,

what makes me "worry" with my low budget is to buy a HD8 while I have a pair of TR4A HS6 and a pair of Strombergs in stock.

 

Marco

looking forward to watching the progress keep posting cheers David

[Tim D.]

For the record I am running with a CR of 8.9:1. It was the lowest I could get to easily without to much modification. It runs 4psi fine and will run 7psi but you have to watch it pulling from low revs in some situations.   Probably could dial the pre-ignition out with some more work on the ignition time. Marco, What ignition system are you using? I run an aldon amethyst system which allows boost retard. 

Tim

[Z320]

1 hour ago, Tim D. said:

For the record I am running with a CR of 8.9:1. It was the lowest I could get to easily without to much modification. It runs 4psi fine and will run 7psi but you have to watch it pulling from low revs in some situations.   Probably could dial the pre-ignition out with some more work on the ignition time. Marco, What ignition system are you using? I run an aldon amethyst system which allows boost retard. 

Tim

Hi Tim and Peter,

I don't know the compression ratio of my TR4A, it runs with the original distributor with vacuum box and a Pertronix I braker.

First I check other basics: what is below the magnetic clutch? Hopefully piece of anything to fix the SC close to the pulley.

The pulley spins clockwise, the magnetic clutch locked with 12 V the M6 screw opens "normal" and easy.

YES! Looks good.

All together again, btw the pulley is for a 6PK multi rib belt, the belt itself is only 4,6 mm flat.

Time for some more thoughts.

Ciao, Marco

Edited March 12, 2023 by Z320

[Peter Cobbold]

Marco, The marks on the nose of the blower suggest to me the inner race of the bearing has been spinning on it - perhaps why it was for sale.

The clutch mechanism is not needed, it jsut adds complication. I would find a way to use the female splined section of the pulley to constrcut a new bearing/pulley assembly.

If the TR4 head has been skimmed in the past you might well get detonation problems. However I think solid copper head gaskets are available for those engines.

Peter

 

[Z320]

Good morning Peter,

thank you for your worry, luckily the bearing inside the pulley spins easy in itself.

The inner race has a wide fit on the nose - but does not move on it. Too easy spinning in the bearing itself.

These SC are that cheap because the Mk1 SLK is 25-19 years old and hundreds go their way to the car wracker.

The guy who sold me only wracks SLKs and offered another SC for 333 Euro (sold now).

Possibly I put the magnetic coil out and try to sell it. This gives me the space for a bracket on the nose.

Still I‘m collecting ideas.

Ciao, Marco 

Edited March 13, 2023 by Z320

[stuart]

Triumph used to do a steel shim plate to drop the compression to suit countries with poor fuel quality. I dont know the part number but someone might.

Stuart.

[Z320]

another one

but please don’t trust on me to get mine fitted and running.

I never did that before, it is your an stupid idea.

Edited March 13, 2023 by Z320

[Peter Cobbold]

Marco,   This graph will be useful when estimating how fast the blower has to be turned in relation to the crank:

[Motorsport Mickey]

Aaaaahhhh Marco I am so sorry for you my friend.

When your darling wife discovers her dress fund account has been raided...this will involve you in a disproportionate amount of pain and suffering... lol.

Mick Richards

[Charlie D]

Hello Marco,

It may well be a stupid idea, but I bet you will have a lot of fun trying to make it work.

I personally have no intention of fitting a supercharger, but will watch your efforts as I did with your MX5 gearbox swap.

It’s just a pleasure to watch such great engineering, the total opposite to my "Bodge it up and hope for the best" attitude.

(Although that does work a lot of the time.)

Charlie

[Z320]

22 minutes ago, Charlie D said:

Hello Marco,

It may well be a stupid idea, but I bet you will have a lot of fun trying to make it work.

I personally have no intention of fitting a supercharger, but will watch your efforts as I did with your MX5 gearbox swap.

It’s just a pleasure to watch such great engineering, the total opposite to my "Bodge it up and hope for the best" attitude.

(Although that does work a lot of the time.)

Charlie

Hi Charlie,

thank you very much, but believe it or not:

in my opionion there is no need for a supercharger and I don't miss one.

But I want to know and see the challenge to do it with a "small budget".

Perhaps finally I'm the same way pleased as with my 5 speed gb?

Ciao, Marco

 

[Z320]

Hi Peter,

my calculation was very simple: the M62 SC pumps 62 cub. inch each turn = 1.016 liter.

The TR4 engine with 2.2 l pumps 1.1 liter each turn, for 0 bar boost the pulley must be 1.016 / 1,1 = 92.36% = 7,34% smaller.

For 0.3 bar (4.4 PSI) boost (absolute 1.3 bar) the SC pulley must be 0.9236 / 1.3 = 0.71  = 29% smaller than the crankshaft pulley?

Some bigger should also work because the compressed air heats up and expands.

So my first test (anytime) für 3-4 PSI boost could be a about 25% smaller pulley?

What do you think about, please?

[Peter Cobbold]

6 hours ago, Z320 said:

Hi Peter,

my calculation was very simple: the M62 SC pumps 62 cub. inch each turn = 1.016 liter.

The TR4 engine with 2.2 l pumps 1.1 liter each turn, for 0 bar boost the pulley must be 1.016 / 1,1 = 92.36% = 7,34% smaller.

For 0.3 bar (4.4 PSI) boost (absolute 1.3 bar) the SC pulley must be 0.9236 / 1.3 = 0.71  = 29% smaller than the crankshaft pulley?

Some bigger should also work because the compressed air heats up and expands.

So my first test (anytime) für 3-4 PSI boost could be a about 25% smaller pulley?

What do you think about, please?

Hi Marco,  You need to correct that 1.1 litre for volumetric efficiency of a running engine (which will be highest ar peak troque rom ca 3000), A figure of 80% is abour right, so the engine pumps 1.1 x 0.8 litres per rev. So recalculate to allow for that. Otherwise it looks about right to me, but its late and I have not run through the sums.

If you know the boost at ca 3000rpm of the donor Merc 2300 - close enough to the TR's 2200-  then the pulley ratio calculation can be checked. Better stiii maybe a TRrer with the Moss TR4 kit can help with boost and pulley data.

3 to 4 psi will be, as you say, calculated for cold air. Actual boost will be hotter, about 5-6 psi and that should be just about OK on 97RON with a 9.5:1 compression head. But freedom from detonation is impossible to predict with certainty , it might need 99RON. And you would still have boost-retard as an anti-knock measure.  Heat is the enemy so design a cold air intake to the carb air filter and wrap the exhaust manifold and fit a heat refectlor. However if you try to run that boost for more than say 10 seconds detonation might start. Water injection is another anti-detonation trick.

When it works you wont want to drive normally aspirated again!

Peter

 

[Z320]

Good morning Peter,

thank you for your explanation!

Do I remember correctly: the compression ratio must be determined on the opened engine?

Measure the compression with a gauge via a compression test gives a higher result ?because of pulsing air?

Ciao, Marco 

Edited March 14, 2023 by Z320

[Waldi]

Hi Marco,

I’m not an expert with screw compressors,

but it could help to look at the Mercedes to TR4 stroke volume and then compare pulley diameters; this would give you a ball park number for your pulley ratio?

I realise these are entirely different engines, 4 valves/2valves, different compression ratio’s but its a sanity check.

Good luck with your journey.

Waldi

[Peter Cobbold]

8 hours ago, Z320 said:

Good morning Peter,

thank you for your explanation!

Do I remember correctly: the compression ratio must be determined on the opened engine?

Measure the compression with a gauge via a compression test gives a higher result ?because of pulsing air?

Ciao, Marco 

I think an accurate measure can only be done with the head on the bench and a burette to measure chamber volume. A compresson gauge has dead volume in its hose and inlet valve closing is never at BDC.

Maybe on the TR4 engine the head thickness measured externally in situ will tell you if it has been skimmed?  (On the TR6 it is the corner above the MU that shows head thickness).

Peter

[Z320]

Thanks all,

my first concern is to get the SC in a possible position and to make the inlet manifold.

 

[Peter Cobbold]

Aligning the crank and blower pulleys dictates its fore-aft location. That means deciding upon the new crank pulley design first of all. Peter

[BlueTR3A-5EKT]

50 minutes ago, Z320 said:

Thanks all,

my first concern is to get the SC in a possible position and to make the inlet manifold.

 

I guess you have studied these photos or similar.

https://www.fenderbroad.com/car/triumph-tr4-supercharged/

[Z320]

My possibilities to make the inlet manifold are limited.

With the SC in a possible position I will decide about the belt/s, pulleys and the inlet manifold 

[Z320]

Hi,

today I did some measurement on the cars engine, found the head about 85.3 mm high.

Minus about 1.7 mm for the head gasket

= 84.6 mm = 3.33" (84.582 mm), ergo the head is original.

Like this head (84.58 mm) on a worn TR4a engine, which I bought some years ago because of the crankshaft and head.

 

I could do what I never wanted to do: rebuilt the hole engine.

With a different gasket I could reduce the compression ratio and do a quick swap.

Some items fitted, with the dynamo back on the engine I hope to find a idea how to fit the SC and how to fit which belt.

Ciao, Marco

Edited March 18, 2023 by Z320