lee Posted October 13, 2016 Report Share Posted October 13, 2016 I say big because it's only the second engine I've built The idea is to get it going Planning to go out to +60 but I hear people say that overheating will be an issue, is this the case? Quote Link to post Share on other sites
Steves_TR6 Posted October 13, 2016 Report Share Posted October 13, 2016 My car has +60 forged pistons, gas flowed and balanced etc, circa 170hp. Built in the late 1990's and totally reliable to this day, with only reconditioned injectors in the last 12k miles. No overheating issues whatsoever, whether potterin, thashing, or sitting in traffic. I did flush the engine 3 years ago using the 'two part' engine flush from i think Holts. Regards Steve Quote Link to post Share on other sites
john.r.davies Posted October 13, 2016 Report Share Posted October 13, 2016 Why overbore? You'll gain about 100cc capacity, at the cost of new pistons and all the work. For a road car??? More power, cheaper, from flowing the ports and chambers, increasing CR, use of a 6-3-1 tubular exhaust and enabling higher revs by lightening and shot peening the rods, balancing the crank, rods and pistons. Etc. And I admire Steve's 170bhp! JOhn Quote Link to post Share on other sites
astontr6 Posted October 13, 2016 Report Share Posted October 13, 2016 Have to agree with John! You may also have head gasket trouble and porous block trouble between the bores? Bruce Quote Link to post Share on other sites
Andy Moltu Posted October 13, 2016 Report Share Posted October 13, 2016 Overheating should not be an issue because of a +60 bore. The TR6 has ample cooling capacity in standard form so any actual overheating is likely to be indicative of a fault. More than that you may have problems with head gaskets as there isn't a lot of room between cylinders 3 & 4. Quote Link to post Share on other sites
Guest ntc Posted October 13, 2016 Report Share Posted October 13, 2016 Remember if you go to +60 anything goes wrong the block is scrap and it will crack. Quote Link to post Share on other sites
TRTOM2498PI Posted October 13, 2016 Report Share Posted October 13, 2016 +40 is safe with routine, high RPM. Mine was built 5 years ago and 50K miles without any issues at all. Used for sprints, track days and endurance events. Cheers. Quote Link to post Share on other sites
Andy Moltu Posted October 13, 2016 Report Share Posted October 13, 2016 Remember if you go to +60 anything goes wrong the block is scrap and it will crack. You can get them sleeved and there's the option to use a block off one of the other big triumphs. Quote Link to post Share on other sites
TriumphV8 Posted October 13, 2016 Report Share Posted October 13, 2016 I made several engines in the range from 76.5 to 78mm. If you expect core shift you will like this tool: http://www.ebay.de/itm/262466237910 You can check and decide what the block accepts. Normally 77mm is no problem. Also overheating is no problem that is bore related. It relates to radiator and thermostat. I would recommend to use modern VW pistons. They are cheaper, hypereutectic, have better piston rings are lighter and are availiable in 76.5. and 77 mm. Also the MAZDA pistons are a nice choice, I have a set of 77.75 at hand and made an engine with them in 78mm. Their advantage is that they are close to identical to TR6 piston. They have to be reworked for floating pin of TR6. As power of the TR6 is difficult to generate I decided not spoil that chance to get some horses for free and the best is, they are not availiable only at higher revs like with a cam or PI or WEBER but they work just from idle...... This is the MAZDA piston This is the VW piston Quote Link to post Share on other sites
lee Posted October 13, 2016 Author Report Share Posted October 13, 2016 Thanks Chaps I've had a few well experienced TR engine builders recommend +60s I am aiming for hopefully close to 180 horses as I can get. It's a US engine so there's plenty of head skimming to do. Billit rods etc, changing everything and strengthening it all. We shall see, I'm having fun anyway Quote Link to post Share on other sites
Guest ntc Posted October 13, 2016 Report Share Posted October 13, 2016 Thanks Chaps I've had a few well experienced TR engine builders recommend +60s I am aiming for hopefully close to 180 horses as I can get. It's a US engine so there's plenty of head skimming to do. Billit rods etc, changing everything and strengthening it all. We shall see, I'm having fun anyway They are telling you bulsh!!! but your money Quote Link to post Share on other sites
Peter Cobbold Posted October 13, 2016 Report Share Posted October 13, 2016 Thanks Chaps I've had a few well experienced TR engine builders recommend +60s I am aiming for hopefully close to 180 horses as I can get. It's a US engine so there's plenty of head skimming to do. Billit rods etc, changing everything and strengthening it all. We shall see, I'm having fun anyway US engine needing skimming....ideal for a blower as it is. Quote Link to post Share on other sites
Guest ntc Posted October 13, 2016 Report Share Posted October 13, 2016 (edited) US engine needing skimming....ideal for a blower as it is. Peter Then show us all a dyno ( engine) output of yours please.Not any links . Edited October 13, 2016 by ntc Quote Link to post Share on other sites
TriumphV8 Posted October 14, 2016 Report Share Posted October 14, 2016 They are telling you bulsh!!! but your money Wise words from somebody who did that work! Some time ago I could see a TR6 head at Stoneleigh from a bloke who claims tuning in that quoted range (with twin carbs) ..... What should I tell.......... Quote Link to post Share on other sites
harrytr5 Posted October 14, 2016 Report Share Posted October 14, 2016 I went to plus 50 thou on the advice of the reconditioner. I ordered forged pistons from America and they will make any size you want still the same price. The size in mm was 76mm. Used Fardon forged rods (uk) and all fasteners were ARP including head studs,nuts etc. The car flies and has been flying for two years with no problems up to date. Regards Harry Quote Link to post Share on other sites
john.r.davies Posted October 14, 2016 Report Share Posted October 14, 2016 I said I admired 170bhp with to gue in cheek! 180?! Some racers may be able to claim that. Kaxtner claimed 200, but that lies only I very high revs, 7K+, and a steel crank and rods are necessary to achieve that. Also frequent rebuilds. Unless you want a race engine, and all the expence that implies, aim at a more realistic bhp figure. John Quote Link to post Share on other sites
Ragtag Posted October 14, 2016 Report Share Posted October 14, 2016 I am aiming for hopefully close to 180 horses as I can get. Schoolboy error. Never, ever quote BHP figures on here, it isn't worth the hurt Quote Link to post Share on other sites
lee Posted October 14, 2016 Author Report Share Posted October 14, 2016 Schoolboy error. Never, ever quote BHP figures on here, it isn't worth the hurt I quite agree, though it's a figure in my head I'm not overly worried If I want proper power I'l take another car Quote Link to post Share on other sites
stuart Posted October 16, 2016 Report Share Posted October 16, 2016 I quite agree, though it's a figure in my head I'm not overly worried If I want proper power I'l take another car Judging by your fleet the 6 is the least powerful of the lot! Stuart. Quote Link to post Share on other sites
alan atkinson Posted October 17, 2016 Report Share Posted October 17, 2016 I said I admired 170bhp with to gue in cheek! 180?! Some racers may be able to claim that. Kaxtner claimed 200, but that lies only I very high revs, 7K+, and a steel crank and rods are necessary to achieve that. Also frequent rebuilds. Unless you want a race engine, and all the expence that implies, aim at a more realistic bhp figure. John Crank or RW? You can get 163 on an engine dyno at 8.5:1 with a .020 overbore. I have the dyno sheet somewhere. It had Carrillo rods, forged pistons, a custom cam and a chunk of head work to get there, but it was at normal rpm. Translated to about 125 at the rear wheels. Bump the compression a point and there's an easy 10-15 more. Just saying... Quote Link to post Share on other sites
Andy Moltu Posted October 17, 2016 Report Share Posted October 17, 2016 Kastner may have made 200bhp in his day but there are racers out there with 6 cylinder TR engines putting out considerably more than that, again with engines revving to 7000+. (in the end engine power is a reflection of how much oxygen you can draw in to burn the fuel ,or blow in if super or turbocharged. I'm excluding Nitrous and trick fuels from that consideration) Bhp measurement in a car is a speculative calculation and engines rarely get tested in control condition dyno's to DIN standards. A rolling road is useful to tune a car but comparing figures from one to other is not possible unless they are next to each other! Quote Link to post Share on other sites
Peter Cobbold Posted October 17, 2016 Report Share Posted October 17, 2016 I dont bother with hp except to get a rough idea of air flows to calculate onwards eg water injection flows. Supercharging gives low rpm torque that gives a different feel to the car than conventional tuning. Flooring the throttle in a bend at 2000rpm the extra torque from 4 psi of boost can be felt helping the steering. I rarely go above 4000rpm as the torque is quite adequate for steep hills, without dropping a gear. And the old Wade blower is limited to 4500rpm = 5000crank rpm. Mostly I drive a gear higher than normal. Peter Quote Link to post Share on other sites
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