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Triumph TR6 - Hi-Ratio Roller Rocker Update

1.75 to 1 Roller Rockers from Jim Swarthout are installed and work in my otherwise stock
'75 exactly as advertised. There is a noticeable and very appreciated gain in power at very low RPM 1500-1600 and on throughout the range, quite a noticeable difference. They are quiet - set at stock .010" clearance. No affect on oil pressure readings. Before installation I checked stock total valve lift on 2 intake and 2 exhaust valves with a dial indicator -averaged .330" - after new rockers installed checked at average of .398" - actually this is a lower amount of total lift than most 'performance grinds'-the GP3 cam from Richard Good, for example, is .405" and the Triumph S2 cam also had valve lift of .405". I decided to change valve springs and used those sold from British Parts NorthWest - they are not an extremely high pressure spring set and using Mr. Swarthout's (special for Triumphs) valve spring compressor ($40.00) the switch was extremely easy and fast. Aside: What was very strange was that the new springs seemed to require much less effort to compress than the stockers.(Could the 28 year old springs become work hardened ?) The oil flows nicely through the new nitrided rockershaft- though certainly at a much lower rate than what I had expected from my experience with racing motorcycle engines. I am not worried at all about this and will not use the external oil line kit. As I mentioned in an earlier post I am going to supercharge this engine over the winter and decided to put the rockers on with the stock engine to separate one modification from the other. So far, I am very impressed with the workmanship of the roller rockers, the performance they give, the instruction manual that he provides is superb, and from Mr. Swarthouts enthusiasm and excitement regarding Triumphs. His company is new and there are often glitches at the beginning of a new venture - delivery delays and so on. I am very satisfied so far with his products and also admit I've just installed them - driven only about 75 miles in the last two days, so this is,obviously, a 'first' report. By the way, I am a full paying customer with no connection with Mr. S's business. The delivered price of $216 is very high value in my opinion. I'll report further as miles accumulate, though I'll be 'off the road' in 3 to 4 weeks to start the supercharging project. I hope this helps provide some useful information for you. All the Best !
David Johnston

Thanks for the info. I looked at Mr S's page and can see no design flaws, in fact they look just fine, think I'll give 'em a try. Where did you find the nitrided shaft ?
Will be very interested to hear what happens when you supercharge. Peter
Peter Gooch

David,
Great to see another enthusiast for supercharging. Those high lift rockers will be perfect in ablown engine. What blower are you going to use?
Peter
(Wade-supercharged TR6)
P H Cobbold

Bought the nitrided rockershaft from BPNW.
http://www.bpnorthwest.com/tr6/tr6.htm
Great service and people - approximately $75 as I recall.
David Johnston

Hi Peter, I'm using the Eaton M62 using a replica of the Vintage Induction Systems setup. And thank you, Peter, your enthusiasm and encouragement demonstrated in your article describing your car was a major factor for me in making this decision. Those of you who have't seen Peter's article are in for a treat --http://triumphs.50megs.com/blower1.htm
I am really excited to begin the installation, I've been "buying and storing parts, reading and researching" for almost a year now-it's time to get to it. So Peter,have you made any major changes to your setup since the article appeared ?
David Johnston

Hi David,
One big change I would make if I were starting out again would be to use that Eaton blower- the Wade is three times the size and restricts max rpm.
I looked up the patent that VIS took out, to try to find how he eliminated mixture bias between cylinders- there must be baffles of some sort inside the inlet manifold. (On my setup the inlet duct does that job, but with the blower mounted on the engine inlet manifold you will need to induce swirl somehow.) Mixture bias can be a serious problem- the lean cyliders can detonate. So I would recommend finding out how VIS did it!
I think you could probably also go for more max boost than the VIS (which I think was 6psi)by running the blower faster. It all depends on the octane of the petrol available to you and the compresssion ratio. A second SU would then help reduce the blower inlet depression(so less power needed to turn the blower and probably a little less heat generated- but space could be problem.
I can assure you that you will be delighted with the feel of the blown engine- it will be well worth the effort.
I'm always happy to help if i can: my email address is (respell it to defeat the spammers):
pcobbold@briishlibrary.net

Peter


P H Cobbold

There are a host of in-line mixers that can be used to insure uniform mixing. Of course, better mixing comes with a price - more pressure drop. That shouldn't be a problem with a "blown" engine, though. The first thing to do is make sure the carb is at least 20 diameters from the manifold split to the cylinders. Then there are other options like "fingers" every so often to help induce turbulance. That can involve some serious metal working, so getting "fully developed flow" by length is the easy option.

Brent
(I dabble in engineering...)
Brent B

I also am running Jim's RRs. I've had them about 2000 miles now and am beginning to hear a very distinct ticking. I need to pull the cover and re-adjust. I too am planning a supercharged conversion. I started out buying parts and now feel as though I need some engineering advice. I have Corky Bell's book "Supercharged! Design,Testing,and Installation of Supercharger Systems" and am feeling a bit overwhelmed. I don't mind sharing in this thread my direction and was wondering if any of you are engineers or are minded enough to give advice. I have a great machinist to help with this.
w Holtzclaw

Brent,
Maybe you can throw light on what VIS did. The blower mounted on a flat rectangular plenum chamber no more than 2" thick. The outlet port of the blower seemd to be immediately opposite the two ports on the original carb manifolds. So the required mixing had to occur in a space around 1-2" deep and say 10" long and 6" tall.

wH,
I agree Bell's book is a bit heavy going. If you can get a copy of Alan Allard's book (published by Patrick Stephens) it is much more accessible. Unfortunately its out of print but it seemd to me to be more in tune with classic cars- it was written when they were new! I am very happy to give advice- either here or by email. I am not an engineer (although I do have some science behind me, but in biology- my physics is from schooldays) so that should encourage you to press ahead. Your engineer will be able to advise on designing the parts- some photos of the VIS kit would help him, and there are drawings of it on the US Patent web site. You will need to calculate the fundamentals like blower gearing- is that where your feeling a bit overwhelmed? If so I can take you through it step-by-step from first principals.
Peter
P H Cobbold

David,
One modifacation I do plan to make is to improve the cold air supply to the air filter. Although it sits just under a bonnet scoop I find that in traffic hot under-bonnet air rises and the engine will start to stumble after 15 min tick-over (from a cold start). IIRC the VIS kit has the carb sitting to the rear of the blower with a simple air filter bolted to it- not ideal. You need to get cold air up there!
Peter
P H Cobbold

Peter wrote in part:
"Brent,
Maybe you can throw light on what VIS did. The blower mounted on a flat rectangular plenum chamber no more than 2" thick. The outlet port of the blower seemd to be immediately opposite the two ports on the original carb manifolds. So the required mixing had to occur in a space around 1-2" deep and say 10" long and 6" tall."

Not seeing it makes it really hard to say what's going on. There are really two problems here - mixing the air/petrol, and providing good distribution of that stream to the inlets. This sounds like a box plenum to connect the blower discharge to the two ex-carb ports. In something like that a series of perforated metal plates could be used to even out pressure pulsations (coincident with each lobe of the blower coming to the discharge) and provide good flow distribution to both inlets. The baffles would also do some mixing.

If the stream is mixed going into the blower, it will be mixed coming out. I'd concentrate on mixing between the carb & blower - which means don't mount the carb on the blower, and good flow distribution on the outlet, which would mean a plenum with perforated baffles.
Brent B

I did wonder if VIS had used a couple of sheets of expanded metal sandwiched togheter at right angles. But as you say without seeing it in the flesh its difficult to judge.
The Eaton blower should do a good job of smashing up the fuel droplets- it will be turning faster than the crank ( max. 16000rpm!) and has a spiral rotor like the GM jobs only with tighter clearances. So that plenum chamber probably just needs to baffle the flow.
MossUSA has just released a kit for the MGB-it might be good idea for David and wH to see how they have fitted the blower.
P H Cobbold

The VIS manifold has no specially designed
pieces to distribute flow more evenly --Nick Formica the enthusiast (and 6-Pack Member)who actually first came up with this supercharging option started by buying the bare case of an M62 supercharger from Magnason Products (Calif.) and built a plenum out of plywood to see if he actually could mount the supercharger to his TR6 !! He fabricated pieces of aluminum with a hacksaw and did a lot of experimentation - he's an energetic and creative guy. Then when he thought it "might work" he cut the pieces of aluminum to match the size of the plywood plenum and took them to a welder for assembly. (I can just see Peter C. grinning)
After he got it back, he tried it out and it started right up and with just a few carb tweaks - ran prettty well. His story is documented in a nice article that appeared in the 6Pack July 1997 magazine, with pictures of the plywood too ! (This magazine article is available from 6Pack as a back issue for something like $4.00 - it includes the whole issue) One thing that he was absolutely amazed by was that the plugs on all six cylinders burned evenly and with no detonation. Incredible.
Got to run.
David Johnston

I got the big idea for supercharging by driving my wife's car- a XJR. 4.0 liter, 4200lb blast! I've been a car nut all my life and have done 2 ground up resto's,69 Corvette 427/435, and a 72 TR6, owned and maintained myself 5 XJSs(v-12s), converted a TR6 to a Chev v-8, and a MGB to the Olds 215 v-8 (to name a few). I still come back to my 6 though for some strange reason. I started out buying a Lucas PI unit and wanted to s/c with it, but soon realised that was not a good idea. I then bought 3 Lucas throttle bodies(single air balance type) and had my machinest drill out the holes where the mech inj. went to accept GM style injectors. Took all of the TPI wiring ect, off of a 85 Olds with a 3.8 liter engine to adapt for engine management. Batch fire, this particular year used the o2-maf to provide fuel curve vs programed controllers starting in 86 (sequential fire). Bought a roots style blower off of a 95 Toyota Previa 2.4 liter. Also bought a intercooler off of a Isuzu NPR to top it all off. I have bought a spare engine to begin mock up. That is when I came across Bell's book. When I began to do the math for pully speed, displacement of blower ect, ect, is when I became overwhelmed. I now question where I am in this project. A interesting article can be found at http://www.slantsix.org/articles/dibiase_efi/efi-conversion.htm . Somebody help!! Oh yeah, also am going to keep A/C on this puppy.
w Holtzclaw

You are all MAD DOGS! Uh - will you let me take 'er for a spin when you get done??

Brent
anemicly aspirated TR6
Brent B

Need help with supersizing your six? Check out Mitch Seff's at http://www.angelfire.com/ny4/triumph5/. Eaton & VIS fully functional with a single SU carb.

Rick O.
Rick Orthen

David,
Problem solved then!
When I had my blower inlet manifold welded it distorted horribly so I now use a simple propane torch and a 'soldering' kit called Lumiweld or Technoweld. Its brilliant- no distortion, really strong, and DIY.


wH,
You need to find out what that Toyota blower pumps per revolution.The data must be available somewhere ( did Eaton make them for Toyota??)
Start by calculating the volume of air the TR6 engine will consume at max rpm, say 6000. Thus: engine displacement is 2.5l, but its a four stroke so in 1 min it will consume 2.5x 6000x 0.5 litres ( which is 7500litres per minute). But it does not succeed in fully filling a cylider in each rev so multiply this figure by the 'volumetric efficiency'- I used 80% as a guess ( giving 6000 litres per minute actually inhaled). So if the drive to the blower spins it fast enough to deliver 6000 litres per minute (when the crank is at 6000rpm) the blower will supply just enough air to fill the cylinders. The supply and consumption are exactly equal and the pressure in the engine inlet manifold will be at atmospheric- ie no boost.(Note that Roots blowers do not compress the air internally - you only get boost of the blower pushes the air through faster than the engine wants to inhale it.)

Now you need to decide upon the max boost you want to run- this depends greatly on the fuel octane you can get and the cylinder head compression ratio. If you can get 98 octane fuel and have a 8.5 head I reckon, providing you fit 'boost retard ingnition', that 9 psi will be a safe-ish limit.(As a rough estimate 95 octane would need a 7.5 head). Now atmospheric pressure is around 14.7 psi so 9 psi is roughly 60% of 1 atmosphere. You already have the blower delivering air to give 1 atmosphere in the engine manifold (absolute pressure not guage) so you need to up the gearing by 60% so that the blower delivers 9600 litres per min when crank is at 6000rpm.
This is called 'free air delivery' and takes no account of leakage back past the rotors (giving a bit less psi). Nor does it take into account that the air exiting the blower will be heated by up to 90C (more psi, but no more oxygen), nor that evaporating petrol into that air will cool it down to about 70C. Its a ball park calculation, but it worked for me.( I did not worry about air density ratios etc that the books go into).
The Eaton web site has graphs showing that their Roots blowers give linear air delivery with rpm, so if you get 9psi at 6000rpm, you'll get 4.5 at 3000rpm and a shade over 1psi at 1000rpm. (all at wide open throttle of course) That's where the smoothness an all that torque comes from!!
So once you know the air delivery of that Toyota blower per rev simply claculate how many times faster than the crank it needs to be turned to get 9600 litres output when crank is turning at 6000rpm. That will determine the cank pulley circumference you need, assuming you stick with the original Toyota blower pulley. Then its off to the machinist with the TR6 fan boss as a pattern and the spec for the grooves on the poly-V belt that fits that Toyota pulley.
Peter
P H Cobbold

Thanks Rick, I had missed that site. Interesting he has fitted a cold air duct and has 7.75 CR head with 9psi boost.
Peter
P H Cobbold

wH
That intercooler will not be safe to use if the blower draws through a carb- wet intercoolers can explode at a hint of a backfire! Maybe you're thinking of EFI fitted after the intercooler?
Peter
P H Cobbold

Peter,this particular blower is a sc14 vs the sc12 on the MR2. All I know is that this relates to 1.4 and 1.2 liters. What I don't know is if this is per rev, per 1000, ect. I'll dig around on the MR2 sites and see if any of those guys know. The blower will be on the left side of the engine bay (from cockpit). Then through the intercooler in front of the radiator, then through the maf, then into the Lucas plenum. The injectors are mounted in the Lucas throttle bodies so the fuel will be directed at the intake valve. The injector is about 1 3/4" from the valve.
w Holtzclaw

wH
That's really neat. I chickened out of trying to use the Lucas PI with a blower but so lost possibility of intercooling. From what I've read flow losses in the intercooler mean that a intercooler-bypass is a good idea, opening the flow into the coooler at 6psi and above.
You'll need to beef up the way the Lucas PI plenum chamber mounts onto the PI manifolds- those bent rubber sleeves and jubilee clips wont take much pressure before sliding off!
I cant help with the blower spec- those models of MR2 never came to UK. It sounds to me like the "sc14" describes 1.4 litres per rev. If so it needs to spin up to 6500rpm to give max 9psi. If it is similar in design to the Eaton blowers that is a modest rpm. With an intercooler you should be able to run higher boost!!
I know very little about electronic PI, but putting the air flow valve after the blower means you will need a method of sensing boost pressure ( otherwise the ecu does not know anything about air density as boost changes).
An afterthought: if you can find the crank pulley size on the Previa and the boost it developed at max crank rpm you should be able to calculate the blower's displacement.
Peter
P H Cobbold

Peter, could you e-mail me with your e-mail address so that I may can run a couple of things by you?
w Holtzclaw

Peter, check this out http://www.mr2.com/TEXT/SuperChargerInfo.html
w Holtzclaw

wH
That web page gives the crank pulley dameter for the s/c as being 145mm. What's the diameter of the pulley on the blower you have? and what's the MR2 cubic capacity? Thats all we need to know the get idea of blower displacement per rev.
Its a very interesting set up. Toyota have gone for large boost levels at low rpm- 6psi at 2000!! That low down torque will really give it grunt off the line. Then they spoil it by restricting boost, but that would be in the interests of avoiding detonation. The knock sensor will play a role there too.
Peter
P H Cobbold

The MR2 cubic capacity is 1.2 liter. From what i've always been told about the 2.5, I don't want it to turn over 6000rpm anyway as far as the boost goes. I'll have to measure the pully and get back to you. This is literally my starting point. I will have to get this right and then everything else will be done to go with that. I'm not sure what diameter the TR6 damper is either, yet the new lower pully will have to be made to go over it as I want to go to a serpentine belt and don't have much room in between the chassis crossover and timing chain cover. If it is too large, I will then have to look at having a new pully made for the s/c as to slow it down some.
w Holtzclaw

wH
I use a poly-V belt and that is nearly 30mm wide (it has to be to transmit around 30hp).A toothed belt can be narrower but it will be a tight fit behind the crossmember if it's going to drive blower, alternator, water pump (and aircon?)! You can reckon on that blower taking 20 hp at full boost.
If you make the TR6 crank pulley the same diameter as on the MR2 ( ie keeping the pulley ratio the same) you would get 6psi at 2000rpm and hence 15psi at 5000rpm(crank)on the MR2, providing you disable the blower bypass system. This ratio will be ideal for the the TR6, beacause 2.5 litres is moreorless double 1.2litres. So you will get 7.5psi at 5000rpm. That would be a good starting point I reckon and you would not need tp omplement the electronically controlled MR2 blower bypass.
My regular email server is down- use the welsh one instead.
Peter
P H Cobbold

Peter,the s/c pulley is 12.3cm+/-, the harmonic balancer on the TR is 15.25cm +/-. I still do not know the original Toyota pulley size. I have about 4.75cm between the crossmember and timing chain cover.The stock belt for the Toyota is 1.9cm wide. I believe my best bet is going to be having a pulley made that will go over my balancer, get my s/c lined up with that, and then align everthing else to those. I don't understand using the welsh? server to contact you.
w Holtzclaw

wH
The MR2 web page gives the crank pulley as 14.5 cm. diameter. That means the blower is turning at 14.5/12.3 times crank rpm. If you make new crank pulley of different diameter then a new s/c pulley keeping to this ratio should give TR6 7.5pi at 5000rpm.
Best we re-check this by email!
Peter
P H Cobbold

David,
Just seen this on an MGB site:

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=115&source=T&thread=2003091719352115752

The bit about 'Eaton is not made for a wet mixture'needs looking into. Will the teflon come off the rotors? How did VIS get round this?
Peter
P H Cobbold

Hi Peter, It turns out that VIS did nothing to get "around" this . It was always presumed by Eaton that the bearings within the blower where adequate to deal with a "wet" mixture. Many, many superchargers have been purchased and installed in TR6's and some in MGB's in the last 5 years and used successfully with no reported bearing or blower failures. What is this about then ?
This same M62 supercharger has also been adapted by MagnaCharger (a part of Magnason which specializes in the application of superchargers to the Harley-Davidson market)-- and re-configured for that use. In two cases , both in Australia, the supercharger bearings have been contaminated with the fuel/air mixture, the bearings have lost their internal lubrication and then failed. These engines were "probably" run at very high RPM (6000-7000)in a racing mode, with far less than perfect carb jetting and on a motorcycle exposed directly to the elements. The owners screamed 'bloody-murderers' -- and wanted their money back. Hence, salespeople at Eaton/Magnason are advised that the blower is not to be be "recommended" in the future for a "wet environment" (carburetors) . The motorcycle people at Magna-Charger set out to design a bearing (there are two bearings in the blower case) with a Viton lip that will effectively seal the bearing from the fuel mixture. They have had these bearing since approximately January '03 (that I know of) - for approximately $30-$40 total, for the two. I have purchased these bearings to be "more" , 'on the safe side'.
I have not yet installed them, but they should be easy to deal with-unbolt one end of blower-press out bearings--press in new bearings- this is not the end that requires careful shimming. Everyone I mention this to, who has an installed TR6 blower, seems to think I'm --well, being anal. I am very "experienced" with Nortons, Triumphs,MGB's and feel that a person must be anal if he has any chance of getting out of - and staying out of-- the garage/workshop for very long.
I got this info after quizzing both the auto and the motorcycle people at Magnuson before purchase last December and feel the new bearings will be just fine for my use. Actually, existing installed units are probably just fine also - in the USA legal environment, companies must be truly conservative and Magnason is just playing by the current rules of the game. This has been a rather long winded explanation - sorry. Hope all is well with you-
David Johnston

David,
Thats useful to know- Magnasson are clearly on the ball! My thought is that in road driving most of the time the blower will be off boost and the pressure in it below atmospheric, keeping fuel out of the bearings. Maybe it is only in racing when the blower will be under boost for much longer that the probelm could arise.

Talking of blown bikes, tha nchi8nist who dod my work also was involve din fiitng a small Wade blower to Kawasaki drag racer. The main proble was the SU icing up before the end of the 1/4 mile. Great fuel methanol for cold running!
Peter
P H Cobbold

This thread was discussed between 19/10/2003 and 27/10/2003

Triumph TR6 index

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