Not driving well
Turbo Mini Forums

Hi guys
New too this turbo build.
So I have put the engine all together, the turbo build has gone well. It starts and runs beautifully But I have a problem when driving.
When I go up through the gears normally (haven't tried booting it yet) it doesn't seem to be boosting up but the dump valve is working. The boost gauge is reading -0.5 bar on idle but will not go above 0 when driving. It feels like it's holding back when you tell it to move(it did splutter before I turned the fuel screw up). It does have a manual boost controller if that's any help but I have tried turning it up, doesn't seem to help. Its running a standard fuel pressure regulator (no gauge on it). I have tried pulling choke out to get more fuel in and tried winding the mixture up but doesn't seem to affect it.
I'm not quite sure where to start, whether to ditch the boost controller? Maybe fit a different fuel regulator to make sure it's not leaning out?
Any help would be greatly appreciated
Thanks

When you say it's a standard fuel pressure regulator, is it a rising rate regulator?

Welcome.
Whats your base fuel pressure (between regulator and carburettor, and does the pressure increase either with boost or if you apply pressure the the boost pressure reference on the regulator.
Shane

Where is your boost gauge plumbed in, when you say you haven't booted it, are we talking minimal load and what rpm? If you're running it in, i'd be giving it a bit of beans!

So hopefully the picture I have attached works. Its the regulator that almost looks like a UFO😂
Unfortunately it doesn't have a gauge attached so I'm unaware of what pressure it is putting out.
The boost gauge to plumbed into the manifold and t pieced with the dump valve as per a image off this forum. Like I said it doesn't seem to have any leaks that I can hear and it sounds like it's trying to build boost as the dump valve opens and releases pressure.
As for driving problem, I seem to reach about 3500/4000 rpm and it holds back. Like a N/A engine that isn't getting enough fuel.
Hopefully that helps a bit better

Attachments:

22.17kb

Sounds like it’s running very low boost (and/or lean/incorrect ignition timing) and the boost gauge is plumbed into the vac advance port.

The dump valve wouldn’t do anything without any boost.

In the 13's at last!.. Just

nomal reg issue is if its set too high and pushing past the float valve. you can check that by pulling the dash pot off and running the pump for a bit and seeing coming out the float orofice.


another issue thats been seen is the gasket between the plenum and carb not having the correct holes, and screwing up fueling, it should be obvious if you whip it off and check all casting holes have a coresponding hole.

another posible is just a leaky dump valve, but i'd expect it to show some boost, what dump valve is it?

apart from that, double check the timing, and fueling, you really need a Wideband to tell you anything useful fueling wise.

Also, its always worth swapping the plugs out, especially if theyve been fuely

Right guys. Got the car timed up, runs loads better. But it's only building 0.1 bar of boost. Any suggestions?
I have no leaks and all the correct gaskets fitted

Right guys. Got the car timed up, runs loads better. But it's only building 0.1 bar of boost. Any suggestions?
I have no leaks and all the correct gaskets fitted

Actuator preload? Start with half a hole load.

I have adjusted the actuator arm still not boosting past 0.1 bar, checked the wastegate is working with pump, working fine.

ok, common no boost issues,

you are actually loading the engine? and not just revving it?

leaky dump valve, try blocking it off?

the "original! dump valve leaking, theres a shuttle and spring on the metro plenum set for somthing like 10 psi, if somones been at it and left the spring out.... usually this gets blocked totally to allow more boost, or pacjed with 5 p's to up the pressure so its redundant.

dodgy gauge, or the gauge fed from the wrong point.

the inlet hose to the turbo sucking flat.

The engine is being driven, so not stand still revving.
I'll try blocking off the dump valve, the plenum is a custom stainless one.
It could be a dodgy gauge I suppose. The feed for gauge and dump valve are from the inlet manifold.
Thanks