Author Archives: bowtie6

Wiring Harness

Tonight I started working on the engine wiring harness. Doing an engine swap requires some sort of engine harness to be used along with the computer (ECM) in order to make the engine work. This is the part where “old school” hot-rodders shudder and panic about. This is also the part the trips up many folks attempting to run electronic fuel injection (EFI).

I’ve worked with my cousin Jim for the past 15 years perfecting the fine art of transforming a stock wiring harness into something that can be used to fully run a modern EFI engine in a classic car. At first we worked on “throttle body” engines – basically a glorified carburetor but with the advantage of electronics. These were the early EFI setups that offered much better economy than a plain carburetor but had a long way to go. Throttle bodies evolved into individual injectors feeding each cylinder and more sophisticated ECM’s.

Through the years, we were able to adapt the L98 Tuned Port v8 with it’s distinctive intake with eight runners going to each cylinder. As the L98’s became scarce we moved to LT1’s and LT4’s. During this time, we also mastered the L32 V6 as originally fitted to bowtie6. The next step was the LSx family of engines. Currently we’ve focused on the ECOTEC engine as fitted in Jim’s TR4 and now my TR6.

The throttle body harnesses were the simplest. No much really to figure out. When we started using L98’s and LTx’s in Jaguar XJ6 and XJS conversions, at first we sourced the harnesses. They were not cheap, so we took a stab at using original GM harnesses and cleaning them up. If done properly they make an excellent harness however it takes some effort to figure them out.

This photo shows the harness from a wrecked 2.4 ECOTEC powered HHR. The harness is basically all there; however it must be modified to work with the ECM and placement in the engine fitted to bowtie6. This photo shows the harness after I had removed all the plastic casings protecting the harness. This is done for several reason, among them exposing all circuits and it is easier to trace the wires to decide what needs removal.

We don’t use the original GM fusebox. We also remove redundant ground wires and hot feeds, thus allowing the harness to be much simpler and easier to deal with. Depending on what donor harness you use, certain pinouts on the ECM connectors must be relocated. This is all done by using original GM Factory Service Manuals.

I’ll have more as the process takes shape. This is actually a lot of fun however it is a little time consuming. At the end of the day, it is a very rewarding feeling when the harness allows the engine to run.

Things You See on the Road

Coilovers on a TR6

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When bowtie6 was built the first time, we used coilovers on the rear suspension. A special bridge was made and welded to the frame to hold the top part of the coilovers and tabs were welded on the aluminium control arms to hold the lower part of the coilovers. This was nice, the horrible “lever shocks” used on stock TR6’s were removed and all was good.

We thought about using coilovers up front but the way the original Triumph frame is constructed did not allow for a very good placement. So instead, I used SPAX shocks with upgraded aftermarket “racing” springs. This setup worked quite well – but with a huge shortcoming. What shortcoming?

We all know factory Triumph TR6’s require the dreaded “spring compressor” to take the front suspension apart. This in itself is not a big deal (provided one uses the correct type of spring compressor), however the constant tension from the spring loads up the front suspension something fierce. This load forces the driver use great effort when turning the front wheels at parking lot speeds. What?? Well – until you drive a TR6 with coilovers you will have to take my word for it. With coilovers, one can turn the steering wheel with very little effort. Huge difference. Coilovers also allow the use of different spring rates. One can tune the suspension to his needs very accurately. Finally, one can control ride height very nicely with coilovers.

The downside is price. Good quality, rebuildable coilovers are not cheap. Sure, one can source coiloves from eBay or some half-quality supplier. Good ones will run you about $400 a pair. By the time you order the appropriate springs you can have $1000 a set. But they are worth it!

The following gallery show some pics of my coilovers mounted on the new frame. There are some pictures of the front as well as the rear suspension, with the solid axle. One interesting note: Take a look at the frame: there is nothing that hangs below the frame line.

Oh and the coilovers, yes, they perform as nice as they look!

bowtie6‘s Frame Failure – Revisited –

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I have a few pictures with the rear section of the original frame on bowtie6. This frame was as about as pristine as could be found when I bought my car several years ago. There were gussets made and welded onto the frame, as well as reinforcement plates. Every weld on the frame was gone through and reinforced. Yet with all this work, after some 15,000 miles the frame failed.

The following pictures show the seam that failed. Granted the rear is far from stock, but this goes to show that you can weld on the original flimsy frame but this does not guarantee it will survive. The original frame might be OK for the anemic tractor engine that powers “original” TR6’s, but if you are going to put some real horsepower (and torque) in front of a TR6 then you might want to rethink if the frame will hold up or not. In my case, sadly the frame gave up the ghost.

The picture above shows the Nissan R200 “long-nose” differential we used. This diff came from a 280ZX and worked very well – however, it was quite heavy and did not have posi-traction. The ratio was quite nice – actually a 3.90 to 1 – and this was the reason we chose the 3.80 to 1 for the solid axle currently being installed. The picture above does not show the coilovers however, that can be found on my “old” website. The failure happened on the left side (the passneger’s side) and the following picture shows more about it…

In the above picture you see the crack on the tower that supported the coilovers. Here is another shot:

As you can see, the top section of the frame “lifted” off the rest of the beam.

Finally the above picture shows what the rear of bowtie6 looked like. The diff is in the centre, with the custom made halfshafts. The Nissan diff is held in place by the two bridges, the dual exhausts can be seen as well as the rear sway bar. This was a nice setup and would still be in place except for the crapy Triumph TR6 frame giving away…

Seriously folks. No joking aside. I spent a considerable amount of resources on this “original” frame with the work we did to it. Yet, it failed. No, I did not abuse my car but I did get down on it in such a way that I could enjoy the upgrades. For anyone remotely thinking about doing an engine swap using the original frame: think and double-think what it is you want to do.

The original diff will never hold up. Eventually after you put enough miles on it, it will fail. Ditto for the frame. Once again, the section that failed might have not been “original”, but we had a pristine frame to begin with. I hope these article and pictures are of value for you.

bowtie6‘s ECOTEC Custom Intake

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Lots of new progress to report this weekend.

Solid axle & Posi-Traction differential – check
Disc brakes (on all four wheels) plumbed with hand-formed stainless lines – check
Handbrakes using original TR6 cables – check
Wilwood proportioning valve – check
ECOTEC using custom/factory mounts – check
Fourth Gen Camaro hydraulic clutch – check
AISIN 5 speed gearbox on custom mounts – check
Tilt steering on a Triumph TR6 (I’ll have more on this later) – check

And the pièce de résistance for today’s post: a hand formed aluminium intake.

The factory ECOTEC comes with a very intricate and quite impressive composite intake manifold. The thing has a very unique shape, with a convoluted “S” shaped intake that splits the aft of the throttle body into four runners feeding each intake port. With the longer runners, lower torque is improved. Too bad we could not use this intake. Why? In the TR6 the steering shaft is in the way and the front fender would just not allow the factory intake to fit.

So what is one to do? Answer:

GM makes these cool plates for the exhaust and intake ports that are intended for exactly this type of application. The exhaust plate has already been used to make the exhaust headers on bowtie6 (if you haven’t seen that, CLICK HERE).

Now the intake plate along with my cousin Jim’s serious welding and fabricating skillz yields the following:

The intake is fitted for a trial fit and the all-aluminium body is yet to be fully finished. Here is another set of pictures:

The photo above shows the front section of the custom intake. The fly-by-wire throttle body will bolt to the flange on the front. Not shown on the picture above is the port for the MAP sensor as well as the bung for the vacuum line going to the brake booster on the right. Which, by the way is from a Vette along with the mastery cylinder. What are those blue thinggies on both of the brakes lines? Hmmm… Wonder what that is all about??

Last but not least, another view this time towards the front of the car. Yes, that is an all aluminium radiator up front. The fan is SPAL (the same kind used by the boys from Maranello) mounted on an aluminium shroud. Why the shroud? I covered that in my original explanation in my original website. Want to read about that? CLICK HERE.

Pretty cool, huh?

the bowtie6 blog

For this Triumph TR6, the road goes on forever and the party never ends…