Blow through HS8 issue
Turbo Mini Forums

Hi. I have another feed just before the carb mouth.

I'm no expert on this so thanks for the help guys.
I did a test tonight .
I took off the dash pot and piston, put a hand pump to the float bowl fitting to pressurise it and fuel shot out the jet , so as WIL said the way I had it plumbed might have given the bowl a weak pressure signal. So if the carb throat pressure is higher than the float bowl pressure the fuel from the jet will stop flowing . This would explain why the engine goes leaner when the boost pressure rises.

Edited by GARRICK.CLARK on 19th Sep, 2017.

How about just buying a hif44 and factory plenum? These were used on the metros and montego / maestro turbos and could easily make over 250hp.
That would basically be plug and play if you put the montego spring, jet and needle in it...

Yeah that's possibly what I'm going to have to do. I just don't like being beat ya no.
I will try again over the weekend , if no joy al get 1 .

And how about a few pictures of what you have actually done ???

Diagnosis over the internet is hard enough even with pictures but without them, near impossible.

I can't see why plumbing through the float bowl lid shouldn't work ???

Edited by Rod S on 20th Sep, 2017.

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

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Yes, this is the problem you have.

But why is the question. Is the restrictor just not doing its job?

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

www.twin-turbo.co.uk

This thing about fuel coming out of the jet hole if you apply pressure to the float bowl. What am I missing here? Surely this is exactly what it would be expected to do if there was no equal or similar pressure above the jet to push the fuel back down?

Simple question.
Does your regular look exactly like this:

http://www.ebay.com/itm/like/371732228210?...6&ul_noapp=true

Or this:

https://goo.gl/images/anJSES

These are the only fuel pressure regulators known to work properly with Blow thru carb set ups. Top is the
Malpassi (or exact copies of) as used on all the mg turbo and lotus turbos, and bottom is the Renault turbo unit (the rarity of this is why I could only find a grotty image of one...

Edited by TurboDave16V on 20th Sep, 2017.

And on the 7th day........... God created turbochargers!

Hi Guys, I'm rubbish at putting up pics, when I do via photo bucket they cover it up with an update message. I could email it to someone on here. I'll take a close up pic of the carb and pipe work and send it to one of you guys on here.
So My reg is a Malpassi FPR014 There black if anyone wants have a look.
Wil. I don't think the restrictor is doing its job. I could be wrong but I think at the moment I have an amount of pressure in the bowl that is equal to the inside of the carb. If I had enough pressure in the float bowl under boost fuel would push UP and OUT of the jet to stop me going lean. My needle has been thinned out also.

Dave , My little test of blowing air with a pump into the bowl and seeing the results is just telling me how it works. I'm new to SU's.
The fuel shooting out the jet tells me if I get enough pressure in the bowl while the motor is running Then the motor should go really rich. Even flood out

Edited by GARRICK.CLARK on 20th Sep, 2017.

Adding images:

Navigate to http://www.turbominis.co.uk

Click on "my photographs" in the top RH corner.

Log in (if needed - same user/pass as this forum)

Click on "browse" and navigate to the image on your phone/laptop

Click on "upload"

Bosh. Done.

Done. I need a close up really

It looks like it should work, but I find few references online that the reg you're using is suitable for turbo with carbureted use. The bottom half looks the same as the stock malpassi units, but has a raised upper, presumably to allow for a MUCH larger spring. My honest concern, is a regulator able to regulate to 88psi, has insufficient resolution to accurately and repeatedly regulate to pressures 1/100th of that.
Yes it might work, but it might not do what you want. I feel like it might be ok, but it has to remain an unknown...

http://www.gsparkplug.com/fuel/fuel-regula...fuel-regulators

You also seem to misunderstand the carb operation - the vacuum over the jet is what sucks fuel up. You don't want to have too much pressure in the float bowl vs the trout otherwise the fuel is pushed up with too little vacuum; conversely too little pressure and there isn't enough vac to draw the fuel up. I suspect the balance here is where you're struggling with; and the dynamic vs static is not the same.

I struggled for a long time with a custom plenum and a simple smaller hole to create the restriction, but once I replicated the OE plenum restrictor, all fueling issues were fixed.

Hey Thanks Dave for putting the pic up. I do wonder if I will ever get it right. At the moment when I drive it I feel that it is close. It takes off from a stand still really good The front rising to the shock limit. Then no more fuel. I'll keep trying different ways for a bit longer ,Then I'll try a different carb.

Is that blue elbow on the vacuum side of the carb a rigid pipe or a soft hose? what about the two black elbows on the plenums?

because if they are they'll probably suck flatter than a witches tit.

I do think it needs a real plenum once you get the fueling right.

also we need close ups so we can actuially see whats going on.

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

check you havent got the feed and return swapped, this will give a massive pressure pump side (well what should be the return)

Hi Sprocket. The 90 degree black elbows are fairly rigid, The blue 90 in front of the carb is softer and with vacuum is it goes suck in on itself. I am going to fix this once I get the fuel working. Good spot.

Edited by GARRICK.CLARK on 21st Sep, 2017.