1965 Hillman Imp with Honda Goldwing flat 6. Gordon Murray has contacted me with advice !!!

[stevenery]

What a cool cruise!

[yoeddynz]

Cheers Steven. It was a super fun night. Great summery carnival like vibes!

[sladey]

Nice knob

[yoeddynz]

If you were here in nz I'd let you touch it.

[KS]

If you were here in nz I'd let you touch it.

For god's sake don't encourage him!

[yoeddynz]

I'm here to share

[yoeddynz]

I have still been dealing with exhaust fumes entering the Imp when the side windows are down. We were planning a weekend trip to visit mum and go to a car show. Considering this trip would see us doing over 400km I thought it time to try a new exhaust tip design. Enter exhaust box version 3.2

I cut the 45 degree tips off just before the bends, added about 20mm to the remaining tube and then welded the tips back on but this time pointing down towards the ground at around 45 degrees. This I hoped would catch the air stream that runs along the side and under the car better..



Well it was certainly a bit better but still not good enough.

But the trip was great. Brilliant weather for the whole weekend and a really good turnout at the Blenheim Hospice charity car show. The Imp was well received and looked very cute nestled in between two huge cars..







The engine performed really well on the journey both ways. I sat with all the modern traffic at circa 100kph but on the hills I gave it the jandal and had a good laugh on the twisties - surprising many of the other cars I imagine. Filled the tank back up to the brim each way and we got 5.7/l 100km over and 6.3 on the way back (because whilst in Blenheim I took a couple of mates for some hoons up the valley. In old money that's 50mpg and 45mpg. Bloody stoked with that considering the cost of fuel right now.

While at the show we met an old friend of my older brother. He's had Lotus Elan series 4 for well over 30 years. Its a tiny thing. Its narrower than the Imp by 100mm! Hannah was quite smitten by it and was taken for a drive in it later that evening.



He also has a Lotus Esprit Turbo..



But the star of the lot was is this beauty. In my opinion the last of the good looking fezzas.



Its a RHD 355 with the very rare Fiorano handling pack model and with only 20k on the clock. Its simply stunning. I'm very much looking forward to being taken for a spin in the near future. That engine at 8500rpm will be something I'll cherish hearing in person. Here's Hannah checking it all out as if we were buying it (dreams)..



Now back to the real world and that exhaust of mine. If you go back a while when I had made exhaust box version 2.0 - the single side exit buzz box. I wasn't smitten with that design as it had a decidedly tinny exhaust note at certain revs...

https://youtu.be/2b8CUm4J7Jo?si=4vWy-PniGJFa8_Qx

But what it lacked in sound it made up for by pointing the exhaust away from the low pressure zone behind the car. On the long trip south to Christchurch and back never once did we get any fumes in the car. So I will copy it. Time for exhaust box version 3.3

I cut the 45 degree bends off the tail pipes and luckily had some left over shiny stainless tube the correct diameter. This I welded on, smoothed the welds off, masked and painted..



Bolted back up to the box. These new pipes extend a further 20mm than the single pipe on box 2.0. I figured that worked well but just to be sure I'll go out a bit further. I can always chop them back down but as it is I think it looks fine. I like the black with silver tip look too..





I only just bolted these back on this evening so I'll wait till tomorrow to see if its a success. I'll report back with my findings. Fingers crossed.

[911hillclimber]

How did it go?

[yoeddynz]

​Gordon Murray contacted me

In a dream.

He has been following my imp build with much interest and upon reading about my fumage issues decided to reach out with some ideas he had on how to sort it once and for all. He invited me to his workshop for a brain storming session. We drank some strong coffee and went over his ideas, sketching some lovely technical drawings together. I'm the fella on the left btw- but I guess that's pretty obvious to those who know me well..



In my dream we did several long days of engineering to build what Gordon believed was going to sort out my fume ingress and also help keep the rear end planted. Gordan told me he was not a big believer in dropping sacks of sand in the front an Imp to keep the front down. He said he'd had many boring pub Barries tell him over the years that the F1 would have handled better with a sack or two in the front. Anyway, in my dream we finally had this beautiful creation sorted. You can tell from my stubble that some long hours went into it...



I woke up after this dream with renewed confidence and full of vigor. I was going to replicate Gordons ideas and it was going to be amazing.

Sadly my engineering skill set, nor funds, allowed me to match what the team at Gordon Murray automotive can build. But its pretty close and I'm excited about the first tests...



The placement might not be bang on but there's room to move it about, unlike Gordons system which has no adjustability. I'm quite proud of my future proofing and look forward to hearing back from Gordon if he does actually indeed follow this build.



Now with regards to my crankcase ventilation system that I had previously mentioned might be the cause of the smell.

I took the car for a quick drive with the outlet mounted outside the car. It was in the evening, light fading and road to Kaiteriteri was empty - mine for the taking. Its such a giggle giving the Imp some proper jandal up a twisty climb, especially with no passenger to worry about. Its an 800kg car so having 70kg less makes a decent difference.

A run up the hill and back down with the tube venting outside did make a difference. There was definitely less smell. Possibly still a trace getting pulled in and back under the car as the pipe was mounted very close to the bodywork.

At the bottom of the hill, with the engine still idling I disconnected the pipe from the crankcase outlet. Instantly the engine bay filled with fumes - really highlighting to me how much I'm dealing with. I reconnected the original tube that goes to the air filter venturi and went for a another run up and down the hill. The fumes were back.

So I have two things to look at..

Firstly - I need to work out where the fumes are getting into the car on the underside from the filter area.

Under the car I noted the handbrake rubber seal was a bit perished. Fumes could be dragged forwards along the tunnel and into the cabin through the tiny gap. There's no boot over the lever either. I cant even remember if Imps have one? Its a bit unfinished looking. I'll think I'll make a leather boot and seal it up with that.

The coolant pipes that enter the cabin under the rear seat and then exit back out to run forwards under the car both have gaps that allow air through.



I had actually already sealed the main entry from the engine bay..



But not the exit point out the floor. I'd never thought of this as an issue.





So I popped out to what is currently the 'Goldwing' garage..



Box of various foam used for packing bicycles when travelling abroad..



Plus foam from the box of foam and rubber (everyone has a box like this don't they?)



I sealed up the gaps from the top and from below. You can see here how fumes could possibly be dragged forwards if the car indeed does have a low pressure zone beneath it (it certainly will now due to the Imp being a much improved GMA designed fan car) ...




Secondly - I need to re-route the outlet from the catch can to a point closer to the engine. There's a bit of thought needed here as the Goldwing engines have a pretty basic crankcase ventilation setup as standard. The fumes are simply pulled out via the breather vent into the air box above the carbs and drawn back into the carbs to be burned. Being so close to the carb mouths means that even with the throttles shut there's enough vacuum to pull the fumes in...



My current setup is like this. Be wowed by my very carefully altered technical drawings - no help from AI - I don't need it. My hand drawing using a Samsung S pen is simply flawless...



You can see how simple venturi I'd built into the air filter mount is only going to drag the fumes away when its getting decent airflow. I think with a closed throttle situation after a bout of acceleration the filter fill ups with fumes and rather than getting pulled into the engine they are permeating out of the filter and pulled into the cabin.

So my idea is to do something like this...



I'll change it to pull the fumes into the inlet via a pcv valve into the throttle body. If I use the existing inlet that the idle control valve feeds into it'll be on the engine side of the throttle so a constant vacuum even at closed throttle. You can see that tube here...



Hopefully I can close the throttle down enough via the stop to allow for the extra air at idle. Some re-tuning will need to take place.

Most crank case venting systems which have an extra vent to allow fresh air to be pulled in. But the original Honda system and my setup do not. This is a something I had asked about on the Goldwing forum years back when putting the engine back together. I'm not sure if this is a big issue though. The key thing is that the crankcase is never pressurised and whatever blowby fumes are created are pulled out.

I cant imagine the engine intake can pull enough air volume via the fairly small pcv valve or associated tubing to somehow create extra blowby?

I have some pcv valves and lots of tubes to make something up..



What are your thoughts on all this Gordon?

[911hillclimber]

Hello, Gordon with the secret race car here.

1
Stop drinking that coffee...
2
On my flat 6 Porsche race car I have a very very simple breather system that works (in a race situation). Do you need to make this a 'closed-system' for the regs (ie MoT) in NZ?
If not just take the crankcase vent tube to a separate 'tanks'. I use a screen wash moulded bottle with a screw top. Bring the vent tube to it via the screw top.

Drill a 6 mm hole to allow the air flowing from the case to escape to atmosphere, but any oil droplets in the air/mist from the engine will tend to 'condense' on the side wall of the bottle.
If the engine is in poor condition (ie rings loose) then there will be a build up of neat oil in the bottle, if there is non then the engine is quite good.
If you stuff the container with stainless steel wool that will scrub the oil from the air very efficiently.

None of this is rocket stuff, it has been used in race cars for decades.

Just a thought.

This is the best picture of my breather on the race car, it is the box with the bungee strap round it, vent tube coming in from the top.

[yoeddynz]

Hey Gordon with 911 race car. I'm very sorry for this late reply..

Yes your system is somewhat very similar to the original goldwing setup. Theres a plastic capture tank which can be drained. The tank is vented back to the carb mouths (for emissions)

I've actually remade my catch can. Now alloy as the steel one has a split, looked ugly and was going rusty.

I've also vented one cam cover so fresh air can get pulled in. I'm still testing it. If you're interested I'll report back.

[911hillclimber]

Always ready to read about other solutions!

A free consultation with Gordon Murray, how good is that?!

[yoeddynz]

Maybe Gordon leaned some stuff from me too? Perhaps we'll see a goldwing powered lightweight special from him soon

Back to the imp and the real world now.

Exhaust box version 3.4

When I was building this current exhaust box 3 I machined up some spare flanges for the exhaust outlets just in case I wanted to try alternative designs. It was now time to try something new for a couple of reasons. While I don't mind the look of the straight out the side 3.3 tips I'm not quite sold on the sound. When the windows are down I feel each occupant is only really getting the sound of one pipe. Although there's an X pipe within the box I still wonder if the majority of the sound is that of a 3 cylinder?

With both exits pointing straight back then the sound is one of a 6 cylinder. Only one way to figure this out. I decided to make a couple of stubbies and point them down to the road.







The design is not bang on how I wanted them to look because I've run out of stainless bends so I'll order more bends and change the design. For now I can at least try it out and I'm hoping that maybe directing them down into the flow nearer the centre I might catch the air streaming under and away - plus it sounded pretty cool last time I had some pointing down

I had noticed a while back that my steel catch can had a split and was weeping a rusty oily mess - steel not being ideal the condensation within. So I made a new one from alloy. Similar design but without stainless pot scourers inside. I painted the outside with black wrinkle finish paint. One can barely see the catch can hidden away in the back of the engine bay but at least if someone does look it'll look neat enough.





I also decided to add a fresh air vent into one cam cover as an experiment. As I had showed with teh drawings on a previous post Honda don't do it this way on the Goldwing 1500/1800 engines. I sure they know what they are doing and maybe its because on a bike there was no easy way to add a cam cover vent that wasn't either ugly or in harms way?

However most car engines have vents in and out and I just like the idea that the engine sump can have fresh air pulled in to replace the drawn out blow by. So I removed the cover on the air filter side of the bay then drilled a hole in the back where it cant be seen...



I then machined up a little vent boss..



Glued in place with my favourite JB weld.



This vent gets fed from the old spare stub on the air filter via a tube that loops upwards first, to avoid oil running down to the filter (This I learned pretty quickly..)

There's also pcv valve in the line now so it cant breathe backwards.

So far so good. I don't think the engine breathes very much anyway as its a low mileage unit. I'll just have to see how much oil vapour might get caught in the new can over time.

The imp is getting used more than our Cube or Hiace van. Its just proving to be really cheap to run and so enjoyable to use so its the go to daily right now. Here's a couple of pics whilst out and about.

Beach run.



Saab spotting. Cool little car. Ford V4 version. Very tidy.