Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB GT V8 Factory Originals Technical - Nitrous with Hot-Wire EFI

Has anyone adapted a nitrous system with the Rover hot-wire EFI? Or point me in the right direction.

Edd Weninger

Hi Edd,

Intresting idea, I don't how it would be done, might be worth posting on this site
Let us know what you find.


What I have found so far is that there are various systems available for plates that go under 4 bbl carburetors, but nothing specific for EFI systems.

A seemingly good programmable controller is made on your side of the pond, the Maximiser (misplaced the link temporarily).

I plan to design and machine a piece to introduce the N2O and gas downstream from the hot-wire sensor box and upstream of the throttle body, and control the solenoids with a Maximiser or something similar.

Ideally, the system would increase the pulse time of the existing injectors to enrich the mixture when the nitrous is engaged, but I haven't been able to find a good source for hacking the 14cux controller.

This project will take a while but I'll post the results. I don't like to get dusted by Porsche Turbo Carreras.
Edd Weninger

There are kits for EFI they are not really any different than a carb kit..

Well I guess that is not true.. Here is a QUICK summary..

There are dry and wet kits. Dry kits are ONLY for EFI and require the computer to increase fuel flow to compensate. This is how most people hurt thier motors with Nitrous as thier fuel system cannot counteract the NO2 and they spike lean and BOOOM!!

Carbs cannot add fuel so they use what is called a WET kit. higer end EFI kits are also wet kits. These kits add NO2 AND Fuel when the system is activated so your Carb or ECU does not need to do anything more..

I HIGLY recommend running a Wet kit as they tend to be much safer on the motor and are completely independant of what EFI system you are using.. There are a number of specialised kits made for certain vehicles, but many EFI kits are just a wet Carb kit with the Carp plate replaced by a fogger nozzle. You plumb the nozzle in After the MAF but before the Throttle body in the air inlet tube.

I also HIGHLY recommend a Wide open throttle (WOT) switch AND a Fuel pressure switch.

Hope some of that helps...
Larry Embrey

Why can't you just plumb a 9th injector into the same area where you would put the NO2 fogger?

I plan on a wet system with both N2O and gas solenoids operated by some type of programmable controller independent of the hot-wire controller. The programmable controller will allow me to do some graduated testing to determine whether I need to add a second fuel pump to provide sufficient gas volume to burn with the nitrous or if I will be able to tap sufficient volume off the fuel rail 40 psi.

The nozzle design needs to be done and suitable parts machined/assembled. The nozzle/fogger will be installed between the flow sensor and the throttle body.

I have found a nearby expert, Mike Thermos, with whom I plan to discuss the orifice sizes and mixing ratios needed to keep the motor safe.

This will be a 9th injector followed within milliseconds by the activation of the 10th N2O injector. No WOT switch, just a push button...........intelligently used when needed (is that an oxymoron?)
Edd Weninger

A WOT switch is an added level of safety when using or designing a Nitrous system. I can't think of one instance where I would use Nitrous without having my right foot to the floorboards.

I'm sure my timing is fully advanced (minus the retard I program in) and if anything goes wrong all I need do is lift my foot and the Nitrous stops.

My system is a quadruple safe system in that I must 1st arm the system with the main switch (this turns on the secondary fuel pump to my dedicated fuel cell for the Nitrous and also sends power to my NOS programmable Nitrous controller)

The second safety is to then turn on the NOS controller which also controls the MSD 3 stage timing retard box (I so far am only using it as a single stage but the system has room to grow). I have a preprogrammed amount of initial hit in % (pulsed system) followed by a preprogrammed delay time and a preprogrammed ramp up time to my final % of total HP shot that the jets are capable of.

The third safety is the RED button on my Hurst shift handle that must be held in, it allows me to let off between gears when I shift so I donít over rev.

The final safety is the WOT as this prevents the button from firing the solenoids if the switch is not activated.

I have a carbureted system using direct port injection (not a plate system).
Michael S. Domanowski

Sounds like a good kit Michael though your WOT switch will take care of your between shift revving as you should be leting off throttle to shift?? Either way your system sounds well designed!!

Justin - Not sure why you would want to go thru the hassle of an extra injector?? That is just making things overly complicated for no reason. a Wet fogger kit already takes care of all the NO2 and Fuel needs for the system. You could even keep your eyes open at local swap meets for a $150 Carb notrous kit then order the <$40 fogger from Summit racing and be set... Or buy the complete kits for ~$400 if you want new with all directions etc...
Larry Embrey

There's a guy called Perry from over here in the UK who's installed NOS on his V8 B. There are some photos on the following link:

Rick Haynes

Larry, who lets off the throttle when shifting? Ha Ha!
Michael S. Domanowski

This thread was discussed between 04/06/2005 and 14/06/2005

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.