Flat six powered Hillman Imp - now with added cake!

[yoeddynz]

Thanks fellas. Sooooo - does it sound like a (water cooled...) 911 from the short video I've posted? I think it does but there's so much other noise going on in the still very uninsulated shell on a rainy drive - gravel stones, water etc etc

I'm looking forward to getting some driveby vids. Have hannah driving it so I can hear it.

[911hillclimber]

The engine noise will depend on the firing order of the Honda v Porsche I think, but I hope it sounds unique rather than the same, will suit the car far more!

I've had my 911 since 1988 and have only heard it on the track once with me watching a mad journalist driving the nuts off it on a test track here in south England.
It sounded fantastic, but that was about 15 years ago.

Good insulation is needed over a 20 miles journey time i think or you go mad!

[yoeddynz]

Yeah it's going to get some insulation put back in! I've got a roll of good automotive carpet in red to fit as well.

[yoeddynz]

@911hillclimber - Just for info.. The Honda and 911 sixes both have a similar fitting order, well in that they fire bank to bank. If both engines have equal length headers fitted then the pulses and sounds coming out the back will be just the same...

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What I have noted is that since moving my outlets to the centre so they are close there's a smoother sound at idle compared to when they were 600mm, thereabouts, apart when I was bench testing it.
Ignoring the fact the silencers I was using to bench test were basic straight through items and loud I think moving the outlets closer loses the "two separate 3 cylinder" exhaust burble it had at idle.

There is a American built little sports car online somewhere with a goldwing 1500 engine. Might be a 60s Datsun fairlady or something. The guy had built side exhausts. In the driveby footage it didn't sound at all right. Sounded like a 3 cylinder daihatsu because all you could hear was a 3.

[neilbardsley]

Congratulations

Sent from my 22011119UY using Tapatalk

[911hillclimber]

Firing order:
Yep, take your points.
I had a hot 370 bhp Impreza on equal length headers, different sound to stock.
My hillclimb car, a Porsche 911 3.2 @ 320 bhp again on equal length but silencer on each side does not sound like a 911 at all.

But, the Honda sounds great!

[yoeddynz]

Well coming from someone with a flat six that has 3 times the power of mine its cool to know you reckon it sounds good. I'm really looking forward to hearing the drive by sounds this thing might make..

[yoeddynz]

After settling down from all the excitement I had a little break from the car for a day or two while I got some other stuff done. Plus it was raining cats and frogs outside. We ended up getting 160mm (6.2" for those imperial folk) of rain in two days.

I made a rough plan on what I'd do next to iron out some of the issues. The leaks and clutch were the most urgent.

We bled the clutch again. It seemed fine in use on the hoist with Hannah in the car working the pedal in and out while I turned the rear wheels. Bite point still roughly in the middle of travel. But I'm still going to look at the master cylinder because from a peek under the dash it doesn't look that flash...



It has been playing up (bite point getting low) with the Datsun engine and it's not been touched in the 5 years since first getting this imp on the road.

There's a seal kit waiting for me in town and I'll see how good it comes up.

The leaks next. I had a suspicion that the little vent hole in the filler tube was letting oil squirt out as the oil splashed up the tube. I wanted to work out where the majority of oil was coming from before taking the next steps.

Plus I wanted to drive the car some more before mucking about taking things apart.

So I folded up this oil shield with a folded edge that hopefully catches the oil...



'The oil shield 2000' bolted up below the cam belt cover...



Now I can go for another hoon.

But I need to easily spot my revs (because until tuned I'm not going to blindly go bouncing it off the limiter).

My rev counter wasn't working off the signal from the coil pack. I'm not sure what kind of signal that puts out or if indeed its working properly at all. So I swapped the signal wire over to the one from the megasquirt. Still nothing though. The rev counter, being an old cheap thing ($7 from the swap meet) needs a high voltage spike like it gets from the negative terminal of the ignition coil.

Enter stage left a spare relay. I took it apart, removed switch plate leaving just a little coil...





Made this little harness..



Ignition voltage flows through the relay coil to the ecu tach signal wire. The rev counter tach signal wire is connected to the ecu side of the coil. Each time the current is switched off by the ecu it creates a voltage spike to the old rev counter so emulating an old ignition setup.

This was a fun little job made nicer by having 'driven' the imp out into the sunshine. The ground had already dried nicely after the rainy weekend, the sun was hot and it was nice to be working in natural light.



Fitted the little 'Ignition spike generator 2000' in place and now I have a working rev counter...



I'd also folded up a bit of alloy, stuck some double sided tape on and remounted the water pump controller angled upwards so I could read the bloody thing ^

Note how generally untidy that lot is. I really want to remove the lot, put it in a bin and rebuild my own dash and instruments. That is future Alex's job though. Time for a second drive.

Boy its quick! I let it get up to about as hot as it could and did a spot of auto tuning. The tune was improving all the time as I tried to drive in as many areas on the fuel map as I could. I still didn't want to drive for too long because I was aware that the oil leaks were no doubt covering the whole back of the car with a fine mist of muck but I gave the throttle a bit more jandal (actually bare foot) and took it up to 5k. A mix of genuine surprise, shock from going that quick in the imp and mechanical sympathy held me back from going any higher.

Its wicked!

It really snarls.

Very much looking forward to getting better footage including some drive by clips so I can give a you all a better idea. Its much quicker than I was expecting from what should be a stock 100bhp (but could well be less or maybe a little more) and I figure its the 115lbft torque that's making it feel so punchy and fun.

Once back home and into the workshop it was up into the air to see where the oil splatter was at its worst. Sure enough most of it was around the filler cap area. That vent hole. Luckily its very easy to undo one screw and remove the filler neck. See the little hole here, above the screw hole...



I filled it in with some quiksteel epoxy putty and refitted it with a smear of sealant around the joint and screw head just to be sure.

I also made this.



Its a cablestay 2000. It stops the O2 cable from going for a sneaky wander across the top of the oil filter pedestal and straying too close to the exhaust headers...



One other issue I have been thinking about (too much) is the coolant system not getting hot enough. From extensive sofa residing google searches there's a few Davies Craig pump/controller combo owners in colder climates who can't get their cars up to temp, or at least not very quickly. Interestingly it was often Triumph car owners. Stags and Dolomites etc.

The controller chip runs the pump through 3 main settings.

At warm up runs the pump for 10secs on, 30 off until it reaches 20 degrees below the user defined target temp.

Then it goes to 10 on, 10 off.

At 5 degrees before target temp it has a lineal ramp up to pump on full time.

Ideally it should be able to pump slower or for less time when its cold outside because on these colder days (circa 10-15 degrees) takes quite a long time to get up to even 80 degrees if the target temp is say 90-95. I was getting a bit too thinky about all this, doing lots of frantic googling and getting ready to type a strongly worded email to Davies Craig.

I was also prepping to build a thermostat housing, just as some had on various threads I'd read. I even bought some alloy. I wasn't keen on this happening though. Adding restriction is one of the main reasons for premature pump failure (according to other threads..) plus it was going to be adding more ugly things to go wrong.

But common sense prevailed...

Goldwing engines seem to sit at around 87-90 degrees when cruising right and while they can happily handle more heat I have no need to chase it.

Its pretty cold here. About as cold as I'd normally expect to see when I might be out in the car. Summer is bloody hot. Be happy it stays cool easily.

Finally.. up the target temp a few degrees higher so the controller sits in the lowest flow rate possible. Rest easy me.

So we went for another drive this evening. A good strop. Up some hills. Did more tuning. Tried to see as much of the fuel map as we could and let the program do its thing. It was getting better all the time although the fuelling will only end up as efficient as what I have set as targets. If I have that wrong then it'll always be wrong. Lots of driving to do so I can tune areas more by the seat of my pants and what feels right.

But it was already much better and I was getting more confident and it was fun. Not so much for Hannah who was trying to hold onto the door and the laptop at the same time though.

Clutch seems to be holding ok and the bite point seems ok but I'm still replacing that seal.

At one point we heard a sound and saw something bouncing on the road in the cars wake. I stopped and checked the engine bay. Nothing amiss. Then I looked at the oil level (that little light under the cap never gets boring..) and the level was down. Hmmm. No signs of oil mess on the rear though. Maybe its just the oil level when the car is idling and hot...

We drive up the road again and spot that the thing I must have clipped with my wheels was a bit of roadside marker.

Go home now. Play is over. Its getting dark. Onto the hoist...



No signs of mess at all on the back like the last two drives. Have a look under the car..



Clean as. The slightest hint of oil on one rear sump bolt. But no drips. Result !!! It must have been that vent hole.

The low oil level? I checked it with the car on the ground again hoping it had risen as the oil drained back but no. Then I released the cap and the oil level in the filler tube rose. Ha. It's that well sealed. But really it needs a vent so there's no pressure changes. I'll have to look into it because I don't want oil pissing either. Going to be tricky with such a low cap.

Other things I have done is go on more romantic dates with Hannah to the wreckers where we looked for bits. I got these to try out for the basis of my custom instruments. If I can get the speedo head working fine with my Toyota speed sensor then I'll strip it further.

[sladey]

DIY rev counter! Impressive stuff! glad the car is going so well - good testament to your hard work and skills

[911hillclimber]

Some of the best bits right there, fixed this, fixed that and a romantic date with The Loved One in the breakers!

sounds so so familiar...

Not sure this car will ever get finished (with a bit of luck for us here), always look forward to the next bit!

[yoeddynz]

It'll never be finished....

Very much looking forward to building a new dash layout.

[stevenery]

It'll never be finished....

Very much looking forward to building a new dash layout.

No way! You have a very big back catalogue of finished projects. One of many... https://oldschool.co.nz/index.php?/topi ... guzzi-rat/

Most certainly could develop further, but that is the way! What is your plan for carrying bikes? Perhaps a nice roof rack?

[yoeddynz]

Picked up the clutch MC seal kit from town while there for the weekly shop. Got home, removed the fuel tank to gain access to the pedal box, removed the cylinder and stripped it. Like I said , its been 5 years since I last had it apart.

I'd like to blame this time span for forgetting what the main seal looks like.

Or I could just blame my own stupidity for not looking up Imp seal kits before ordering what I thought was the right kit in because what I'd bought doesn't look much like what I needed.

Oh well. The seal doesn't look too bad, nor the bore too worn. The seal could have sharper edges for sure but it would just have to do because I wanted to go out for a good drive the following day. I'll sort out replacements for the future.



I reassembled it all and Hannah helped me bleed the system, again.

Seems ok so we got all the blankets that used to be in the car and covered the rear parcel shelf in a bid to quieten down the engine thrum.

This morning dawned a bit chilly with high cloud. Since it was about 6 degrees I used that as a chance to further tune the cold start. Once warmed up I tried sorting out the hot start. It would always start but then die unless I held the throttle open and let it settle to idle. If I didn't hold the revs up it would stumble into in the low revs/high load area on the main fuel map and I thought that was too rich. So I leaned those bins out. Got sick of mucking about and we went for a drive. By the time we got near our morning coffee destination the sun was out and it was lovely!

We had a date to meet up with another oldschooler and there he was, waiting with his small rear engined noisy toy by the beach. I took some pics. Its one of the few cars that makes the imp look large...







Dylan went for a hoon in my imp and then I in his x19. The various folk about the carpark with their dogs and kids must have had a giggle. We both must have looked clown like emerging from these tiny low cars. I'm 6'2" and Dylan is even taller. It was great to try out a x19 with a proper amount of power and it sounds great. I'm looking forward to when my Imp is properly sorted so we can do some spirited cross country drives. My throttle tip in from idle was a bit sensitive and inclined to bog down making it tricky to get used to.

After a good coffee we parted ways and Hannah and I went home. On the motorway (Tasman 'motorway' that is.. there's like 3 areas with decent passing lanes) I was able to see how it was at higher speeds. It cruises along effortlessly at 100kph pulling around 2900rpm. Luckily the 'its getting boring now' exhaust boom is not around that zone. I'm going to have to do some work to the exhaust and try to tune out some of the drone. I have ideas already on how.

Before getting home Hannah took some driveby vids. Once home I threw them together and popped them up on the tube. It sounds great. This is the first time I have heard it properly as such. Please do it justice and listen to the vid on a decent sound system because phones won't do the low notes any favours.

https://youtu.be/wxyxGCCo2as?si=Ao5nFexZ7MiN-soI

Once home I had a play with the off idle area of the tune. I started by adding fuel back to the area I'd removed it this morning and this improved it muchly. I tweaked it, tested it, tweaked it until it was now much easier to open the throttle from idle without going lean and lurching. Then the hot start issue. Turns out I just needed to add more seconds to the 'crank to run taper time' in idle control. 5 seconds wasn't enough. Just kept adding time until its started and settled gently down to idle.

Those who have tuned their own efi projects will understand just how satisfying this shite is and also how frustrating it can be until you learn what needs to be done. So I ended the days tuning on a little high and decided to tinker no further so left it at that. I put the imp on the hoist, up in the air and checked for leaks. But for a tiny weep from one bolt area there's nothing. In fact, touch wood, this is now the least leaky of all our vehicles!

[911hillclimber]

It really sounds good!

Secondly, got chatting to an Imp guy racing his car at a local hillclimb here in the UK, place called Prescott in the Cotswolds.

Within a few seconds we were both chatting about your project!

[yoeddynz]

Cool. I imagine word is getting around about it.

Ive been to Prescott a few times to watch the racing. #retrorides forum in the UK used to do the gathering weekend there for a few years. Then they did it at shelsy Walsh, of which I've been to once or twice for the same gathering.

Ive a cousin in Surrey who's husband, Robert, races a very very smart sunbeam imp. He used to race them years ago and then more recently bought this one, spent a huge amount getting it restored and converted for racing. Here's a pic from the imp Facebook page of it...