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SpeedFreak

What's inside ?

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I am new to TR6's always lusted after one, now bought one, so here goes.

I imported a good looking TR6 from the U.S.A.  which has had a recent engine rebuild, looks professional, nice coat of paint all over, yes I know thats no indication in itself, however , a rough finish is an indication of lack of attention to detail.

A recent visit to the rolling road showed that it has 103BHP at the engine, now I assume that in 1970 this would have been SAE. The rolling road figure is DIN so that should be worth + 15 to 20%

The compression figures are 185PSI. average with all well within 10% of each other. and yes I have checked the guage and they were taken cold at WOT.

Should I assume ( hope ) that this has had other work i.e. cam replacement ?

Any help, comments, would be greatfully recieved as I am new to the forum.

Richard..

Edited by SpeedFreak
Typo's

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Depending on whether its had its smog equipment removed or not then that would be about right for a US carb equipped car.

Stuart.

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Thanks Stuart, a 1970 build year so no smog kit.

Having read other forums re compression ratios I am still unsure as others with PI's have quoted 140PSI. ?

Richard..

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1 hour ago, SpeedFreak said:

Thanks Stuart, a 1970 build year so no smog kit.

Having read other forums re compression ratios I am still unsure as others with PI's have quoted 140PSI. ?

Richard..

Possibly had a head skim?

Stuart.

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Richard,

i am confused. You say you have a carb car with 185 psi and only 103 bhp ?? Measure the head please. 

Jochem

Edited by JochemsTR

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Though they are supposedly calibrated, I think various rolling roads come up with various differing peak power figures.

When I had my CP series TR6 on a rolling road a few years ago, it made just 126bhp add the flywheel. The technician said that it was the best near standard TR6 he'd seen, as most injection cars struggle to make 120bhp on his particular rolling road. 

My point is, rolling road figures can't be compared with book specifications. However, a rolling road is the best way of optimising fuelling and ignition settings.

Nigel

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The reason I asked since the numbers do not match up. The 185 psi notes to a modified head. Since only 103 bhp was generated, it seems your camshaft may be out of sync. 
Measure head height. This tells you whether psi value is plausible. Next step, measure cam lift. With cam lift you are getting closer identifying camshaft.
Jochem

PS assuming spark timing is correct. Did you measure this? @idle, 1.500, 2.000, 2.500, 3.000 .... ? 

Edited by JochemsTR

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Thanks for the interest Jochems and Nigel, in answer to both of you, yes I am aware of the problems with rolling road data, however, I am using this as a start point before modifications including EFI. And I want to know what I am starting with.

Jochems, the head thickness measured by vernier on the car is close to 85mm. I hope this helps, I will try to post the r.r. graph soon but the reading was 103 hp. 149 f lbs.@ 4665 & 2685 rpm respectively.

Richard..

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with a 85mm head it confirms my thoughts.....the numbers don't add up.

1. check cam lift

2. check timing spark

3. check cam timing

Jochem

In case you are looking to swap cams anyway, you can ignore 1. and 3.

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Nigel and Jochem thank you for your input. I am sure that I am in danger or trying to teach my grandmother to suck eggs, however, from what I have been able to find on the internet and forums the question of h.p. has not been satisfactorily defined.

I am of an age where I used to see today’s “classic cars” in the showrooms new. Prior to 1970/1972 British cars were rated in SAE HP as DIN had not been introduced to the UK. As I am sure you know the difference between the two is significant so I am not unhappy with 103 DIN hp at the moment from a carb car that was originally rated as 105 hp ( SAE ?) and your comment Nigel about CP and in fact CR cars makes sense to me as CR cars rated to SAE and now tested to DIN makes sense and CP cars we’re probably tested according to DIN which had been accepted by 1973. 

I await thoughts on the matter !

Edited by SpeedFreak

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What is the conversion factor for DIN to SAE HP? 

I thought it was tiny, like 1.014. (less than 2%)

Peter W

PS Would any of these help?  https://spicerparts.com/calculators

 

Edited by BlueTR3A-5EKT

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My understanding is 15 to 20 % we are talking early SAE, I am sorry I don’t recall the SAE number, I will look them up later.

Under the early SAE regime engines were tested on a dynamometer with short exhaust stubs, no alternator/ dynamo, no cooling fan and possibly no water pump or fan belt, that is worth more than 2% ( I think you are confusing the latest SAE which is more in line with DIN ).

I hope I am not adding confusion out there ?

Thank you for your interest.

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Richard,

Early US Carb car:

- 104bhp @4500 with 132 lbs-Ft @3000

- 516323 head with 3.4375 "

- compression across 120-145 psi

You car:

-103bhp @4665 with 149 lbs-ft @2685

- xxxxxx head with 3.346" 

-compression across 185 psi

Correct ?

Jochem

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Yes Jochem, correct head for a US car, to get back to my original question, I know the engine has been rebuilt and I am sure that the power output is nearer 120 bhp compared to early SAE standards, look at the torque figure 149 compared to 132 as factory spec. I just want to know if anything else might have been done before I wade in with my spanner’s and hammer ?

thanks for you interest .

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54 minutes ago, BlueTR3A-5EKT said:

What is the conversion factor for DIN to SAE HP? 

I thought it was tiny, like 1.014. (less than 2%)

Peter W

PS Would any of these help?  https://spicerparts.com/calculators

 

Isn't that the conversion between HP and PS?

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13 minutes ago, SpeedFreak said:

Yes Jochem, correct head for a US car, to get back to my original question, I know the engine has been rebuilt and I am sure that the power output is nearer 120 bhp compared to early SAE standards, look at the torque figure 149 compared to 132 as factory spec. I just want to know if anything else might have been done before I wade in with my spanner’s and hammer ?

thanks for you interest .

The head has been skimmed quite a bit so the CR is probably higher than the standard UK spec of 9.5. You can try and measure the valves opening and closing to get an idea on the cam but the only definitive way is to take it out and look.

Did you not get any documentation history with the car?

If its running well and has had a recent rebuild then you probably don't want to start taking it all apart again.

Is it running on carbs? Did the rolling road operator confirm that the mixture & timing is OK?

Darren

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23 minutes ago, SpeedFreak said:

I just want to know if anything else might have been done before I wade in with my spanner’s and hammer ?

Measure cam lift across and spark timing. Or do you want to replace the cam?

Jochem

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Hi Darren and Peter W,   Seems I have started a separate  new topic ( can of worms ) so here goes.

Prior to 1970 U.S. and of course U.K. engines were tested to SAE Gross ( J245 ) standards, this is without ancilliaries such as water pump, alternator/generator, fan, fan belt, air cleaner, restrictive exhausts etc. so was an unrealistic Gross output under ideal conditions.

After about 1972 engines were tested to SAE Net ( J1349 ) standards that aligned more closely to current DIN standards i.e. with all ancilliaries fitted and corrected for Temp, Pressure etc.

The confusion over the conversion factor seems to be that SAE Horsepower is defined as 740 Watts and Din PS is I think more like 736 Watts ( I stand to be corrected ).

As an aside, I wanted an engine powered alternator for boat use so I fitted a 50 amp alternator to a small generator engine ( 3-5 hp probably ) direct drive, connected it up started the engine switched on and the engine stalled immediately, another bright idea down the drain, but it does show the drain on HP from such ancilliaries.

Thank you all but I still do not know what might be going on in my engine so has anyone seen my set of AF spanners? and thank you Jochem I will check cam lift asap.

Edited by SpeedFreak

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14 hours ago, SpeedFreak said:

Thanks for the interest Jochems and Nigel, in answer to both of you, yes I am aware of the problems with rolling road data, however, I am using this as a start point before modifications including EFI. And I want to know what I am starting with.

Jochems, the head thickness measured by vernier on the car is close to 85mm. I hope this helps, I will try to post the r.r. graph soon but the reading was 103 hp. 149 f lbs.@ 4665 & 2685 rpm respectively.

Richard..

Hi Richard,

Looking forward to seeing your progress with EFi posted here, it's becoming more and more popular as a conversion for Triumphs. And with good reason, a well sorted EFi conversion on a Triumph six is wonderfully tractable and more fuel efficient, all of the character with none of the original drawbacks!

That said, I'm happy with the Lucas PI on my '6 and enjoy it for what it is, an interesting piece of period engineering.

Nigel

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I will keep you posted Nigel, it won’t happen overnight as it now looks like I will take the whole drivetrain out as I also have an overdrive to go on.

The efi will use CP type throttle bodies with the injectors in the original places and the distribution manifold fitted where the original mechanical fuel pump was so as to retain a near original look, I have nearly everything ready except an air filter can.

Richard..

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Richard - sent you a PM last night which is showing up at my end as not yet read - a PM is a personal message which goes straight into your forum mailbox which is the envelope icon in the top right hand corner of a forum page - if it has a red flag on it, it means there is an unread message inside it. You can also set up your options to be sent an email if you get a message.

Cheers Rich

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27 minutes ago, SpeedFreak said:

I will keep you posted Nigel, it won’t happen overnight as it now looks like I will take the whole drivetrain out as I also have an overdrive to go on.

The efi will use CP type throttle bodies with the injectors in the original places and the distribution manifold fitted where the original mechanical fuel pump was so as to retain a near original look, I have nearly everything ready except an air filter can.

Richard..

I like the sound of your EFi plan! Multiple throttle bodies have been found to work better than a single TB when a long duration cam cam is used. The 280 degree CP cam has been known to cause rough running below about 2000rpm with single throttle bodies, apparently due to pulsing between the open inlet tracts. I know of someone who found going to a 270 degree cam cured the slow running problem.

Using the original CP throttle bodies you will avoid this potential problem but of course, they will need careful balancing.

Nigel

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Nigel, careful is my middle name, as anyone who has helped me pick up the pieces of my BSA Starfire, Triumph 900 Leg end, or Ducati Monster will tell you .

Richard..

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BSA Starfire takes me back... Never had one but rode another 250cc grenade when I was 16... A Royal Enfield Continental!

Nigel

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I have a single TB on a common plenum with EFI. The plenum displaces about 3.7L. I have run a WBC 518 cam with a CR of 9.9 for over 7 years. I have had no idle quality issues, hunting, or poor response below 2000 RPM. In fact, I usually drive around 1500 rpm in the city. Here is an article re various camshafts. https://averymotorsports.com/tr6-camshaft-selection/

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