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  • TRMark
    replied
    I've been driving my '73 TR6 since 1975. I had three daughters and even bolted 2 lap belts to the shelf behind the seats. They are grown now themselves, but their excitement at being dropped off at the elementary school in Daddy's TR is the biggest thrill I ever had in my TR. Make sure you have pictures and video of your daughter. She will never forget it.

    All of that being said, I always wanted more giddy up. Several years ago, I added Good Parts GP2 Cam, and shaved the head to 9.5 to 1 while getting a valve job. I freshened up the original carbs. Wow!!! What a difference! The idle quality is as good as it ever was, and the first time out on the interstate I looked down and was cruising at 90 mph without the overdrive. My experience has been that if the carbs are running badly and can't be adjusted, its usually the throttle shafts need replacing. My '73 TR6 has 200,000 miles and still ticking.

    TRMark

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  • L.O. Guvna
    replied
    I will add that it is nice that we continue to find a few hp here and there. It is great to catch up on the bits - what else can we do to the head and cam, for example. While Kai and WBC is dark and hiding, there are others continuing the work to improve the whole package. I still like thinking about the lightened crank - maybe 5 pounds, and how that rotation improved engine balance. We talked recently at a Dallas 6 gathering, about parasitic power loss - even the cam takes away from power, somewhat like an accessory tied in to the crank with a belt.

    Good to see Al's vega pics - thanks for sharing those!

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  • lfmTR4
    replied
    Well said. I’ve always thought of torque as what tears your diff mounts or bends your frame if you don't reinforce them when upgrading your engine. LOL

    Seems like everybody sees performance as HP, but to get it you have to be able to apply the HP to the road hence suspension upgrades. Once that is done, then you have to stop it hence brakes. By the time you’re done you’ve built a new car. Kind of an expensive way to get “performance” as a system which is best and less expensive bought all together.

    Best to just enjoy it for what it is. To me 50mph in a well driven 6 beats the snot out more HP in a straight line. It’s really how you drive it.

    Originally posted by TRick6 View Post
    I have argued blue that it ain't the HP, it's the torque, that turns the earth when you let the clutch out.. In the auto performance world, too much emphasis has been placed on HP, but torque is the work quotient. I want a ton of torque. All earth moving equipment is operated a little above idle but the monstrous torque is development down there so that high RPM's are not needed. There is a HP to Torque relationship when the work is twisting but HP seems to have capture the attention of the auto industry. I guess when it changed over to the horseless carriage it is the animal relationship picturing 2 horses pulling your wagon as opposed to 350 ft.lbs of torque. What is a torque? A force placed on an object to rotate it. What? What does a torque look like anyway? A lower case Greek alphabet T. Heck, I can't relate to that. How does a lower case T move my carriage. It doesn't even look like a horse.
    Last edited by lfmTR4; 02-28-2021, 09:59 PM.

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  • tdafforn
    replied
    I think people are offering very sane advice.. think about how you drive the car and how you want to enjoy it.. these cars were never really intended as screamers but saying that they can be really good fun. I opted for the supercharger option when they were available from Moss.. Lotss of torque from low down so less need to change gear and great in the mountains.. but transmission had to be upgraded somewhat to cope.

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  • TRick6
    replied
    I have argued blue that it ain't the HP, it's the torque, that turns the earth when you let the clutch out.. In the auto performance world, too much emphasis has been placed on HP, but torque is the work quotient. I want a ton of torque. All earth moving equipment is operated a little above idle but the monstrous torque is development down there so that high RPM's are not needed. There is a HP to Torque relationship when the work is twisting but HP seems to have capture the attention of the auto industry. I guess when it changed over to the horseless carriage it is the animal relationship picturing 2 horses pulling your wagon as opposed to 350 ft.lbs of torque. What is a torque? A force placed on an object to rotate it. What? What does a torque look like anyway? A lower case Greek alphabet T. Heck, I can't relate to that. How does a lower case T move my carriage. It doesn't even look like a horse.
    Last edited by TRick6; 02-26-2021, 05:40 PM.

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  • skootch13
    replied
    Exactly why I did GP2 and not GP3. When am I ever going to be at 5500 rpms in my 6? I was worried about gassy smell, startability, smooth running etc. Maybe the GP3 doesn't have those problems, but I wanted to be sure. Mine is quick enough for me.

    Leave a comment:


  • HuhReally
    replied
    To be more clear, the rest is assuming you have mashed the throttle to wide open and you feel the need for speed in your TR6. Engine A makes 131 HP and engine B makes 155 HP but they both make a constant 125 LbFt of torque. That last condition determines quite a bit. Namely, they both will accelerate at the same rate until engine A needs to shift. That engine B has a higher redline than engine A, approximately 1000 RPM higher. This illustrates that when we talk about HP (peak HP that is) for bragging rights etc, it is good to ask, at what RPM? Another example is why do people like supercharged engines? Because a supercharged engine can produce more torque at a lower RPM compared to a NA version of the same engine. That torque is esentially the grunt that accelerates you from that RPM.

    Or for example, you want more HP in your TR6 engine? Get the all the parts finely balanced along with a steel fully counterwieghted crank from Racetorations, then you could safely spin it to 7K. If you changed nothing else, it would have quite a bit more HP.

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  • TRick6
    replied
    Originally posted by HuhReally View Post
    How do you drive? Do you routinely upshift near redline? Or routinely cruise near 5000 RPM? I ask because HP is a linear relationship of torque x RPM divided by 5252. Which means that the driving experience below 5200 RPM is really dictated by the torque being produced. Maximum Brake Torque is directly related to the Volumetric Efficiency of the engine As Long As the ignition timing is optimized at that operating point. This is the where I believe you can have a better driving experience by controlling timing more precisely for your specific engine. Read up on spark hook tests and general theory of engine operation at less than wide open throttle.
    Very real condition questions. I don't generally up shift near redline, but I do on occasion. I never cruise near 5000 RPM; my 5th gear is a 059 to 1 which could push me over 200 MPH with my tire size. I leave that cruise/RPM to NASCAR. I am not the 1st to enjoy a "muscle car;" the auto industry targeting those that do for many years. I am a spirited driver possessing the need for speed as those 1st motorists loving driving and wishing for more power. Very few automobiles utilize the available engine power at all times. What I enjoy is the knowledge of the existence of the horse power and when I crack the whip (wide open throttle), those horses come to life and pulled the wagon at the speed desired. I have also concluded that 10 lbs per developed 1HP is adequate for a narrow short wheel base 2100 lb car as the TR6. Much more without serious chassis modifications could be hazardous to your health.

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  • old6er
    replied
    Originally posted by Jackamo View Post
    SU’s were a recommendation from my local guy when I referred to the article which went with Webers. His opinion was SU’s would provide some performance upgrade while being easier to deal with than Webers. Do you think a rebuild of the ZS carbs would suffice and work well with the other upgrade ideas?
    I bought a nonruning car that had a set of brand new SU's on it when put away. They are on the shelf and I am running a rebuilt set of ZS's. What does that tell you ? Want to buy the SU's ?

    Leave a comment:


  • HuhReally
    replied
    How do you drive? Do you routinely upshift near redline? Or routinely cruise near 5000 RPM? I ask because HP is a linear relationship of torque x RPM divided by 5252. Which means that the driving experience below 5200 RPM is really dictated by the torque being produced. Maximum Brake Torque is directly related to the Volumetric Efficiency of the engine As Long As the ignition timing is optimized at that operating point. This is the where I believe you can have a better driving experience by controlling timing more precisely for your specific engine. Read up on spark hook tests and general theory of engine operation at less than wide open throttle.

    Leave a comment:


  • TRick6
    replied
    Originally posted by Anthony View Post
    I was lucky to have a friend who was a professional drag racer (71 Vega photo below) and engine builder. He has always told me that the head and cam are the choke points on any engine. Performance carbs flow rates are wasted on stock heads and cams. The Strombergs are already supplying more fuel than the stock head can make use of according to him. My head was skimmed to make it true, probably only a minimal compression increase. I did the valve job myself using his equipment. New points distributor. Mikuni carbs for their reliability ( love them). EBAY cam maybe from a GT6 with a slightly hotter profile. Electric fan. AAW wiring. I built my engine with his assistance and our modest touches have made the drive a lot of fun. I was aiming for a more reliable car than the original and the extra pop is a welcome by product. Money is always an issue and I did things that were affordable. I think these cars have a perceived level of performance that is what makes them so much fun not the actual performance numbers. Just remember that all of that new power is delivered through one of the weakest links in the car, the diff mounts. Enjoy the journey!
    Wow Anthony, you knocked it out of the park. Having been an old drag racer and small block Chevy engine builder myself (my little 305 ci 71 Vega pictured), your friend is correct that the head and the cam is where the action is to the engine; controlling the breathing. I would add one very important thing, these little TR6 engines possess one-sided heads, meaning the intake and exhaust ports are on the same side. This design limits, or better still restricts the HP production. Cross flow heads, intake and exhaust ports on opposite sides, are far more receptive to producing HP. Stubbornly I went the route of all out building this little engine the way I learned to extract HP from the little Chevy V8. My results were disappointing yielding me about 125 HP at the rear wheels. This was with a blue-printed big end, a popular cam, extensive head work, a fancy exhaust header and MIkuni carbs (which are amazing), the Toyota 5 speed, and the 4.08 Nissan differential upgrade. I could have gotten more engine HP but the car would have become less and less street friendly the more power I produced. The car was fun to drive but, then I drove Rick Patton's supercharged TR6 and knew I had to have more power. So I sold that TR6 engine and Toyota transmission and performed an engine swap to acquire the performance I wanted. You can click on the signature link to British V8 for a tour.

    So I would recommend that you drive a few different modified cars to determine the level of performance you desire and build your modifications on paper first with real costs for a bottom line. Then double it.
    Last edited by TRick6; 02-25-2021, 03:41 PM.

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  • Anthony
    replied
    I was lucky to have a friend who was a professional drag racer and engine builder. He has always told me that the head and cam are the choke points on any engine. Performance carbs flow rates are wasted on stock heads and cams. The Strombergs are already supplying more fuel than the stock head can make use of according to him. My head was skimmed to make it true, probably only a minimal compression increase. I did the valve job myself using his equipment. New points distributor. Mikuni carbs for their reliability ( love them). EBAY cam maybe from a GT6 with a slightly hotter profile. Electric fan. AAW wiring. I built my engine with his assistance and our modest touches have made the drive a lot of fun. I was aiming for a more reliable car than the original and the extra pop is a welcome by product. Money is always an issue and I did things that were affordable. I think these cars have a perceived level of performance that is what makes them so much fun not the actual performance numbers. Just remember that all of that new power is delivered through one of the weakest links in the car, the diff mounts. Enjoy the journey!

    Leave a comment:


  • L.O. Guvna
    replied
    The hardest lesson any TR6 steward learns is.....there is a ceiling to what we can get out of these motors. The second hardest lesson is learning that the best bang is freeing up the motor. And drive train.

    When you blue print this block, shave this head, move to GP2, flow that head, and all the sexy stuff you can throw at it.....you have maybe....190 at the flywheel. I mean, call it 200 if you want to round up. But stop and think about that number. We all get distracted with a 2018 8 speed camaro with a blower and small spinner, and 600 at the rear wheel. That aint us.

    to lock's point - there is plenty of examples of what you can do. And lock, wolf and everyone else borrowed from Craig Kenyon, Kai at Wishbone, Richard at goodparts....etc. There are good recipe's for improving this motor, but it aint' gonna magically go to 300 or something that puts us in the hot rod category. Mild rod. At best.

    and Pool is your source for fuel delivery. the 175's are great, particularly his that he offers in his program.

    Good luck with your project.

    LOG

    Leave a comment:


  • BWA
    replied
    That classic motor sports article is in my opinion is the go to for modest upgrades for the TR6 engine.
    One thing they did not talk about is the extra boost you will get from going with an electric fan.
    So concentrate on the fundamentals:
    Make sure the internal parts are not worn out.
    Increase compression
    Get the head to breath better
    Go with a mild cam that will take advantage of a better breathing head.
    Free up the drive train from parasitic loss (the air pump and fan)
    Get the engine properly tuned as the original settings were designed to reduce emissions and they ended up reducing the efficiency of the engine.
    Stick with the stock TR6 carbs as they are good as long as they are not worn out.

    I had a 1991Honda Civic SI that had a true 108 hp at the flywheel and the car weighed a bit over a ton.
    By today's standards that does not seem like much but it had lots of zip.
    That little car had ample power to go 200 km/hour (125 mph).
    How do I know this, I put the pedal to the floor on an open highway and it easily did it.
    Jay Leno constantly tells us that most of the legal fun occurs in driving between 40 mph and a 100 mph.
    If you can get the TR6 engine to put out something comparable to 108 hp at the flywheel then you will have a car that has ample zip for some fun driving.

    Cheers
    Byron

    Leave a comment:


  • Cygan
    replied
    You wrote; "My goal is to recover some of the horsepower and then some while maintaining a pleasant drivability " and "I don't want to go crazy with mods, as much of the work will be done in the shop ($$$)...." This is good because it is easy to go crazy with mods. You seem to have an objective in mind. Let's talk about recovering HP. How much HP is enough?

    Bolt on equipment may not give you the boost you may be expecting. A tired engine will not respond as well as it might. So an engine rebuild might be a good place to start. "Power is made in the head" so most folks start with a head rebuild. you have choices here. certainly they will square up the head. Most folks will opt for a 3 angel valve job and install new guides and stem seals. The next thing folks may want to do is deck (shave) the head. Raising the compression on a TR is done by making the head thinner, making the volume smaller and keeping the stroke the same. This is opposed to using high compression pistons. PB mentioned a compression ratio of 9.5:1, because you will still be able to use pump gas. Then you can have the head ported. There isn't a lot of meat there and if too much is taken off then you will break into the water jacket. So you really want somebody who has done this operation before successfully. Smoothing down the flash inside the head and matching the intake ports, the manifold gaskets and the ports on the intake manifold will help the flow.

    You can square up the block and then check the bores for roundness and scratches. If they aren't round or are scratches, you will want to bore the block out to the next oversize piston. Speaking of pistons, you will want to decide if you want Forged or Alloy pistons. Forged pistons are very nice, but they cost a fortune for the TR. If you have decided to go "all-in" and want to put a supercharger on the car, then I would go with forged pistons. I mean after the cost of the blower and everything else, the cost of the pistons are a mosquito bite. You will want to blueprint your old oil pump of buy a new one. The crankshaft should be checked for cracks and the journals tested for roundness. If necessary you can have the cranked turned to the next smaller size bearings. And fresh bearings on a newly turned crankshaft are a must.

    Then you will want to consider the cam. You should do your homework because the cam really influences the behavior of your car. There are lost of racing cams out there that put you powerband up into the high rpm range. The are great for racing, but not so great for the street. You idle may sound like a "box of rocks". Having modeled a few of these cams, almost everything you do will move your power band high in the RPM range. Sticking with the 125 hp cam is a good choice + you won't need to re-curve your distributor. You may find that a fresh engine will give you all the HP that you need.

    Cygan

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