Dipped in green glass

[GT6 M]

here it is,   hidden in the deppths of me comp

M

[Nick Moore]

Oooh, that head is interesting. The injector ports look quite small (for the Lucas PI injectors?) but I guess they could be machined out to 13mm? I don't plan on pulling my head off again - the engine is built, dammit! - but it's a good idea. How close are they to the water jacket?

Marcus, I really have been listening to what you say. The side feed injectors are a possibility, but I hadn't found much info on their flow rates. And Craig's busy making his Mk2 inlet, which has shown that the short EV6 injectors and an extruded fuel rail do fit under a Mk3 bonnet. Just. I'll leave the 'big reveal' to him. I very much like your home made fuel rail though - the Ross Machine rail everyone uses is massive and would be referred to by the police as a blunt object. If I copy your rail though, I'm afraid it won't be red.

As for the single throttle body, I started down that path, but was worried about charge robbing between cylinders due to the amount of camshaft overlap. Individual throttles seemed like a better way to go, and even if I'd started with the single throttle, it would probably have evolved into a six-butterfly setup eventually. It seemed simpler just to chose the evolved option right from the start. The throttles will be hanging quite low, so linkage clearance shouldn't be an issue.

Edit: Craig's just posted a video of his Mk2 EFI manifold to Youtube: https://www.youtube.com/watch?v=9ArkQMSR6os. We're using the same inlet manifold plate, runners, injector pockets and injectors, so if it fits his car, it should fit mine too!

[Nick Moore]

I guess that if Craig has posted his video, then I can show a couple of photos he sent me. The cat is officially out of the bag (apologies to animal lovers).

We're using the same hardware, including the same 32mm runners with 45 degree bends. My injectors will sit where his are located. As you can see, his injector pockets are laid as low as possible, and the bonnet does close. The big difference is of course that he has a single throttle and I'll use six. It should make for an interesting comparison.

Nicely done Mr Trimble.

[BiTurbo228]

Ooh that looks very nice! Do you know how long they are and I can have a go at calculating what rpm you'll get resonance charging at

[GT6MK3]

Cheers Nick.

Full build story with pics here http://tinyurl.com/gt6manifold.

BiTurbo, you can go with 215mm from memory, flange to trumpet.

C.

[BiTurbo228]

Well, according to a couple of different calculations the resonance should peak between 5250 and 5500rpm which is a nice place for it to be. Probably still around when peak power hits for a 2.5l.

That all changes if it's a different overlap cam to the stock TR6 though...

[Nick Moore]

The inlet length may provide a resonance around 5000, but that's not intentional. There simply isn't enough room to make the inlet runners any longer, and even the length we're aiming for is longer than stock TR6 PI manifolds. It won't be seeing high revs very often as it's intended to be an open road cruising car, albeit one with plenty of motivation.

I was going to fit a GT-42 camshaft, but it broke in transit. Andy Thompson very kindly gave me a '43' from his race car when he moved to a '42'. Here's how the two cams compared in his car. I'm sure my horsepower numbers will be lower due to different compression and exhaust, but the torque curve should be similar. And fun in a lighter car!

[byakk0]

You've gone way beyond this stage, but have you looked at the patton injection system?
http://www.pattonmachine.com/TBI-Main.htm

[Nick Moore]

Quoted from byakk0

You've gone way beyond this stage, but have you looked at the patton injection system?

I looked at it briefly. My aim is to produce a modern interpretation of the factory's PI setup, which used six throttle butterflies, but using electronic injection instead of mechanical. I'm much happier tweaking the tuning and timing with a laptop than endlessly fiddling with vacuum gauges, feeler gauges, springs and files, so didn't long consider sticking with Lucas PI. I thought the Patton system was less efficient because it places one injector in each carburettor body and retains the stock inlet manifold, which apparently doesn't deliver equal inlet charge flow to each cylinder. On the other hand, it would have been a lot easier to fit, which I guess is its biggest selling point.

I think Andy Thompson fitted a Patton system or similar to one of his cars, but has since upgraded?

[byakk0]

Good looking setup. Are you going to try for the TRIUMPH lettering on the intake?

Guess it depends on the end look you want, as well as performance. I like the stock look, so I may -someday- go for the Patton system. Bit spendy for me at this point~I'd rather that money go to getting it on the road Not to mention, I'm not much with building that sort of stuff. (I'd certainly learn if I needed!)

[BiTurbo228]

Well with that cam it pushes the peak down to around 5000 so good guess!

It's more a happy coincidence that that's a nice place for the resonance to be

[Nick Moore]

A set of reconditioned short EV6 injectors arrived today. They're the same ones Craig is using, and have been ultrasonically cleaned, tested and flow-matched. The last is important, as a partially blocked injector would cause a cylinder to run lean and could melt a piston.

By the way, the old 0280 155 712 injectors are still available for beer money, low alcohol beer at that. 😉

I've decided to make a fuel rail from 3/4" square steel tubing (I have lots lying around), and some steel weld-on injector bosses are on their way. The steel rail should sit lower than a chunky billet alloy rail, and the end hose connectors can be welded on at an angle rather than pointing straight out like the fittings on the ends of alloy rails. At the front, that angling of the fuel supply pipe might make all the difference.

[Nick Moore]

At long, long last the inlet runners are taking shape (dance)

Brian at Exhaust Innovations has made up six beautifully curved runners. Rather than use pre-formed tube with sharp bends, he's used 4mm thick-wall alloy tube, curved gently using the tube bender he usually makes roll cages with. The runners are 32mm internal diameter - the same as the inlet ports - and flare out to 40mm ID at the butterflies. They're as long as they can be, about 22cm including the 10mm head flange. The butterflies are on the same slope as the engine, and splay out slightly to match the spacing of the throttle chokes. Runner #6 comes straight from the head face so that the rearmost throttle block clears the bulkhead, meaning that by the time you get to #1, the runner points slightly forward. It might be a centimetre or so longer than #6, but compare that to the different lengths of a standard GT6 inlet manifold!

The injector bungs will be lined up with the inlet ports, so the shape of the front runners won't mean that the fuel rail extends further forward than it otherwise would have.

Having not seen the GT6 for a couple of weeks, I had a real "damn, that looks good" moment upon seeing its tail sticking out of the workshop.

[Nick Moore]

We're using my highly precise bonnet space gauge (also known as a piece of fuel line) to make sure the manifold and runners fit under the bonnet. For more precise measurements, we'll probably use plasticene.

As you can see, Bryan spends a lot of time figuring out various ways to fit everything in, and has even started using my cardboard templates. I thought he would have sworn off Triumphs by now, but then I sneaked a look at a Cobra Daytona he's making exhaust manifolds for, and that bar steward is just as tight!

[GT6MK3]

I was trying to work out how this went so long with no comments.

Then I realized that we're all awestruck.


Noice!

C

[Nick Jones]

Quoted from GT6MK3

I was trying to work out how this went so long with no comments.

Then I realized that we're all awestruck.


Noice!

C

Reckon that's about right, stunned into silence........ Noice indeed 🙂.  But you're ahead 'cause yours runs  

Nick

[junkuser]

I can picture myself, leaning on that tyre, planning ahead, drooling or just dreaming of things to come.

[Nick Moore]

Yep, Craig's car runs, so he's winning. Do I get points for tidier wiring?

While the runners are getting welded up, I've been looking into how to run the vacuum lines. There are four things that need vacuum - the idle valve, brake booster, fuel pressure regulator and Manifold Air Pressure (MAP) sensor. The most sensitive is the MAP sensor.

Idle and brakes: I'm thinking of running a 3/4" steel tube (the same as the fuel rail, 'cos I've got lots of it) under the throttle bodies as a vacuum collection rail. It would replicate the vacuum rail in PI manifolds. The idle valve would connect to the front end of the tube, just like a PI's idle bleed screw. The brake booster would connect at the other end of the rail. In turn, the rail would be connected to each runner to distribute the idle air and provide adequate brake booster vacuum. Does this arrangement sound sensible?

MAP Sensor: While it would be easy to also use the booster and idle rail for the MAP sensor, the application of the brakes or the idle valve opening would increase the air pressure in the vacuum rail, which would give the wrong signal to the car's brain. It would think the throttles had been cracked open, and enrich the mixture. So, I've been looking at fitting a second vacuum chamber, unconnected to the first, also tapping into each intake runner. Below is a photo of a Borla manifold on a TR6 from Grassroots Motorsport with just such a vacuum collector - the box with the lines running to it from each intake runner. Hopefully an arrangement like that would provide a steady vacuum signal, but I know that if necessary, noise can be damped out with a canister fitted in the MAP vacuum line. I think Nick Jones once recommended a film canister (remember them?) or fuel filter.

Fuel pressure regulator: Which vacuum takeoff would be best for the fuel pressure regulator? The large vacuum rail for the idle valve and brakes, or the smaller collector for the MAP sensor? Instinct says to use the MAP sensor's chamber, so that the regulator doesn't get confused by the brake booster or idle valve.

[Nick Jones]

Sure, your wiring's tidier now........ or tucked out of sight anyway!  I'm fully confident we can rely on both of you to end up with top notch installs 🙂

To try and answer your question about MAP sensing, I think the only one that will actually potentially cause problems is the idle valve and even then only if the connections from runners to vacuum plenum are too small.  That said, I reckon what you propose is the ideal (if most complex) solution with idle valve and servo on the balance tube and individual tappings taken to a small summing chamber for the MAP sensor and FPI.  It is tempting to just connect to the centre of vacuum rail you propose which would certainly be simpler and eliminate alot of extra clutter and in practice although your instrumentation might detect the effects, the butt dyno probably won't.  The other option would be to use Alpha N (TPS) for load sensing, though I have to say it's not my favourite option as it only infers engine load rather than measuring it.  Might have some benefit with a really wild cam and huge throttle bodies.......

Never knew that Borla thing existed, and reading between the lines it may be that the one in the picture is the only one that does.  Looks really nice, but a pity that they have duplicated the main defect of the PI TBs and made the butterflies way too big.  That MAP connection arrangement is very functional, but damn ugly..... .

The vertical throttle spindles are interesting.  I've been mulling that one as a way of getting bike TBs to sit closer together......

Nick

[GT6MK3]

I'm going to leave the dispariging remarks regarding my Gilligan like wiring well alone.  

I am however looking forward to how you'll package and mount your air filter 😉

But I digress.

Having looked hard at ITB, I have a plan to do it one day.  I reckon you've got some fun bits to look at.  Regarding Map, I think you need to consider hose length.

The folks at EFI hardware have this https://www.efihardware.com/pr.....al-length-connection

Quoted Text

Having equal length hoses ensures each vacuum pulse arrives at the collector so the map sensor can pick up the vacuum signals at the correctly timed intervals. Just like a tuned set of exhaust headers requires all the same length primary pipes to the collector to provide proper operation.

I always figured I'd need 2 taps per pipe, one intake, one outlet.  I havent done the reading, and am happy to be wrong, but how often will you be braking and fueling at the same time?  I always figured that with a large enough outlet off each runner, equal lenght hoses/pipes, and a large enough map collector I would be able to vampire the brakes off the same spot.  Ditto Fuel Reg.

For the intake valve, I figured on a 2nd tapping, with a second chamberand equal lenght pipes.

[Nick Moore]

Hmmm. I've seen the EFI Hardware vacuum chamber. (Google searches always take me to their website now, and I'm not sure whether it's because they have good stuff, or Google is tailoring its searches to my browser history). It would look like a Huntsman spider lurking under the bonnet! Nobody else has mentioned the need for equal length rubber hoses, so I'm not sure whether EFI are smarter than everyone else, or if it is marketing spin. Other firms make up long thin vacuum collectors out of alloy bar, although that might be because it's easier to make them that way.

I might make something similar to EFI's spider out of PVC and see what happens.

Oh, and as for my air box and filter, I want to replicate the 'log', but am still at the head scratching stage. Getting it running is my current goal, and pretty wiring won't help there 😉

[Nick Moore]

The fuel rail fittings turned up today, which was a good excuse to check on progress at the fabricator's. They've welded up the inlet runners, using a spare head I provided as a jig to make sure that the head flange didn't warp. The front injector pocket is in, and Brian is confident that at that angle, the fuel rail will clear the bonnet. Fingers crossed...

He's also ripped the exhaust manifold apart again. I really hate spending money twice, but the first crew made a horrible mess of the secondaries and collector, and it would have leaked like the Titanic. I didn't take any photos of that, it's not something I want to remember.

[GT6 M]

thats gonna give a nice squirt right at the back oft valve.

questionee for ye Nick

will this be up an running befoer in drawing yer pensionee,!!!

Ev a mass attack, get it going

M

[Nick Moore]

Hi Marcus,
It should be running in a couple of weeks. Once Brian has finished making the manifold and fuel rail, the fuel side will be almost done. Then I just have to make a vacuum chamber, mount the throttle linkage and wire up the injectors, and it will be ready to start, and drive.

N

[GT6MK3]

Looking really nice Nick.

Are you going to recess the cups into the rail?

C.