Blow through HS8 issue
Turbo Mini Forums

I'll take some close up shots over the weekend.

My turbo cold side has a small diameter fitting, which a silicone pipe fits on and links to the waste gate actuator. I teed off this SMALL diameter pipe and went straight to the float bowl. Tested it and could hardly drive down the road it was that lean. Reverted back to having the float bowl piped from just before the carb mouth, this made it as it was when I started. Just lean on boost But drivable.
So what's this telling me.
The small diameter fitting on the turbo being too small. I'll bet its only 2 mm I.D. IF THAT. The barbed fitting That's just before the carb is a 6 mm at least.

Edited by GARRICK.CLARK on 23rd Sep, 2017.

Pilot tube next

are you absolutely sure its lean? could it be so rich that it's miss firing?

Schrödinger's cat - so which one am I ???

Hi Rod.
The normal vent hole has been tapped and a small bolt screwed into it with some lock and seal juice on the thread. The float bowl lid gasket has been replaced by a rubber one, It doesn't leak. If it did it would be wet with fuel around the lid and down the sides of the bowl.
The pressure line is a silicone hose that is smaller than the 6mm barb fitting so needs to be stretched over the barb.

Schrödinger's cat - so which one am I ???

I haven't put up any other pics up yet because I just haven't got round to doing it. This vehicle isn't at my place at the moment.
I made and fitted a rubber float lid gasket because the original one leaked under pressure. It doesn't leak now the rubber one is fitted.

Edited by GARRICK.CLARK on 27th Sep, 2017.

Fitted a pilot tube and increased the size of the hose to the float bowl. This has fixed it.

Edited by GARRICK.CLARK on 14th Oct, 2017.

Guys. I have a bit of pinging to get rid of. I've limited the total advance and its still there. AFR is 11. fuel is 95 octane. I have a direct port water inject kit fitted but vacuum is pulling water and flooding the engine. My idea is to fit 1 Nozzle into the breather on the carb. This breather tube is behind the butterfly on the carb and shouldn't be affected by vac. Will this work ok.
Regards G.C

Edited by GARRICK.CLARK on 14th Oct, 2017.

How much boost are you running ? What's your compression ratio ? What have you limited advance to ?

Phil.

WWW.TURBO-MINI.COM

Its running 1 bar ,timing at 24 total, 7.5.1 total.

One major issue with the HS8 would be the jet itself i.e. the hose from the bottom of the float chamber. How do you make it work at 1 bar, these were prone to leaking in N/A engines ?

Another issue is that you need a proper restriction on the carb face. I tried to remove the restriction in the HIF plenum and found out that it was not a good idea. Yes it allowed a lot of air into the carb but the fuel pressure regulator lost its signal and once the boost equalled the fuel pressure that engine literally hit a rpm limit. Got the brass thing fitted back to the plenum in no time.

I also did some tinkering with a Lotus Esprit Dellorto 45. I tried to make it work in blow thru setup with siamese head and it needed major restrictions at the carb mouth. IIRC I had something like 30 mm ID restrictions. In the end I got it working, gained nothing in power but suffered in fuel economy. Now back to SU HIF.

To be honest I would not even consider a HS carb myself but can admire your enthusiasm !

Edited by jukka on 25th Oct, 2017.

Jukka!!! Glad to hear from you

Yes Dave I am still around. And my Mini is still in one piece. Haven´t really done anything with it, maybe 300 miles in 5 years. Had to rebuilt the fuel system due to old fuel ruining almost everything. In the meanwhile, I restored a Mini pickup and converted my Minor to EFi.

Anyway, back to topic: here are (hopefully) a couple of ppics showing the plenum I fabricated for the Dellorto. I machined stub stacks with about 45 mm ID to suit the carb. It plain did not work. I had to put about 30 mm ID inserts into the stub stacks (mimicking the MG plenum) to get the carb / regulator working.

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Hi Jukka.
I've up loaded a pic.
I fitted a pilot tube into the middle of the pre carb flange.
This pilot tube sends a higher boost signal into the float bowl than what's going through the carb. Works great.
To stop any fuel leaking out of the carb under boost all I did is this.
Removed the jet from the carb, fit an O ring over the Jet and refitted the jet to the carb the same way as it came off.
Removed the butterfly shaft.
Machined a groove in both ends of the shaft, Fitted O rings to the shaft were the grooves were made re fitted shaft back on the carb.
Made a rubber gasket for the float bowl lid , That's all I've done.
I also have stopped the pinging.
I drilled out the brass breather pipe that was fitted to the carb.
Tapped it for a devils own jet.
I spray water/meth into the carb which starts at 8 psi.
This stops the ping up to 1 bar.
After 1 bar it pings again slightly.
I maybe able to increase the water jet size to fix this.

Edited by GARRICK.CLARK on 27th Oct, 2017.

Good to here it's working.

I bet a charge cooler would also help with stopping the det.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

Yeah I think so too. I do have an air to air with a fan on it. I may be able to fit were the number plate fits.

Hi Guys.
I'm doing a bit more tuning to my HS8 carb.
I have put enough oil in to the piston so that if I lift the piston to the top by hand some oil will escape through the cap hole.
When I'm driving the vehicle in flat out mode I'm wanting to see oil come out of the cap so I no I'm allowing the most air/fuel into the motor.

Well I see no oil out of the cap hole.


Is it the spring being to strong and not letting the piston rise to the top

The carb should be sealed, including the damper. The HIF44 has a little fibre washer under it. Therefore no oil should escape.

Have you got any measure of AFR? Otherwise how do you know what the fuel mixture is?

The HS8 is a big carb, so the damper won't need to fully raise to flow the air your engine needs.

HOSS

I have a PLX afr gauge fitted. It is rich under boost , Its showing 10 on the gauge
and goes richer with more boost.

Edited by GARRICK.CLARK on 25th Jul, 2018.

Sussed the rich at WOT. Tried another needle.
No success, I realised that the more boost I get the richer the mixture so that got me thinking, what I ended up doing is fitting a blead valve to the boost pipe that feeds boost pressure into the float bowl. Now I have an AFR reading of 12 instead of 10. This means if I increase boost past the 1 bar setting that I'm at now the 12 AFR reading will go down again into the 10's. Meaning I can then readjust the blead valve again to stop being too rich. Hopefully I'll be at 1.5 bar boost .

Edited by GARRICK.CLARK on 25th Jul, 2018.

Nice work.

Phil.

WWW.TURBO-MINI.COM

Hi Guys, I'm thinking of doing a mega squirt conversion, reason being I think the standard points ignition is giving up under high boost/revs. The fuel will be via an SU injection throttle body from Specialist Components. Has anyone used one of these on a turbo engine. Can 1 of these throttle bodies give enough fuel for high HP numbers. I suppose it depends on the injectors really.

P.s I no nothing about fuel injection/mega squirt ignition. So any advice is appreciated.

If the carb setup is working well, why not just try megajolt. So just mapable ignition?