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MG MGB GT V8 Factory Originals Technical - Nitrous Oxide

Apologies to the traditionalists out there but.....

Has anyone experimented with Nitrous Oxide on MGB's with Rover V8's?

I appreciate it's a bit over the top, but with the lack of modification required compared with turbochargers and superchargers for similar levels of power (not on the public highway of course) it seems like a sensible (?) option.

Obviously there are issues on stresses on the engine, handling and breaking, but at around 500 for a kit + NO2 cost it seems a reasonable economy for the occasional drag run / track day.

What levels of power can the standard SD1 engine and gearbox take without resorting to stronger cranks / pistons / springs and so on....?

Don't believe the evil stereotypes!! NOS is THE best bang for the buck power adder at this point.

NOS is perfectly safe for the engine IF DONE RIGHT AND NOT EXCEED the engines normal power abilities. There is allot of myth out there tha NOS itself is bad and break engines. That is like saying Guns kill people. It is HOW the item is used that causes problems.. That said dropping a 300shot into a rover would be BAD set-up.. I would think a 50-100shot would be ablout max for stock unit.

Some tips.
1. Get a WET system. That means the NOS plate will feed both NO2 and Fuel into the intake. Dry kits are cheaper but they are what usually cause reliability and breakage issues. Wet kits will keep you A/F ratios intake which will stop most reliability/breakage issues.
2. Use all the switches and triggers. Base arming switch ont he dash to make system "hot". WOT switch - for wide open throttle only activiation. HOBBS - for Fuel pressure, keeps from going lean and going boom, those are minumum. Also a NO2 pressure sensor would be good.

These items can increase the pruice, but will save the motor and you.. Don't do the ricer trick of triggering it by holding a button on the wheel, that is for movies only..

Good luck and HAVE FUN!!
Larry Embrey

The juice rules on the rides. Go wet with carb and dry with EFI motors. Also if you are building a N20 motor high compresion and duration on the cam is your friend.

You need to check your local laws for a street driver. This may not be right, but I believe that Maryland has outlawed nitrous bottles installed in cars (there may be others).

Wayne Pearson

Any suggestions on locating the bottle? I thought the boot (trunk) would be the best place, but after being badly rear-ended last year, I'm not sure if thats the best plan.

Also has anyone got any ideas on the bhp / torque you can put through the standard SD1 crank / SD1 gearbox / axle without modifcation? Based on ~160bhp-170bhp I believe I'm running at the moment, is a 100 shot a serious option (with careful implementation)?

I will again recommend a wet kit regardless of the system, carb or EFI. A wet kit on the EFI means the fuel system has to increase fuel flow. Some systems will handle that, but many cannot with bigger injectors. Just a heads up. My experience has seen more motors blow due to dry kits and going lean than any other issue.. Again, set-up properly it should not be an issue, but I like Wet as they are stand alone and you don;t have to mess with your normal street tune.
Legality - Yes it is an issue, many states it is illegal. Some you can get away with having the tank in the trunk as long as it is not connected to the lines if you get stopped, Each state and local Municipality will differ..

I cannot speak on the durability of your components as I have no rover experience..
Larry Embrey

Benja, England
Send me your e-mail address and I will send you photos of my system on my 1978 MGB V8 with Olds 215 (stroked to 269 by Dan LaGrou at D&D) with a 300 HP shot of nitrous. I don't use a plate system but have 8 individual fogger jets into the intake runners on the manifold.
Michael S. Domanowski

Hey Mike have you run a 300 shot yet? I'd love to see your 1/4 mile with that!


Justin I'm taking it to the track sometime this summer and I'll post how I do. I first have to modify the system from a single stage shot to a multi stage so I can hit the juice right off the line. I also want to wire in a retard control on the ignition.
Michael S. Domanowski

One of our local MGB V8 owners used a nitrous system on his carburated Rover engined car with some success. The car was un-believable, but he did have some engine problems such as a burned piston and several damaged plugs while he was dialing in the system. It did allow him to run 134 mph timed speed in a 5/8 mile distance.
Bill Young

benja, i just had a zex system installed on my v6 b, it is computer controlled thru the throttle postion sensor, since my car is fuel injection, but they have an add on kit for a carb car also, it is a dry system but has a wide variety of jets and instructions for retarding the timing etc, to mate it , but it limits possible damage to the car because it only comes on when the throttle hits 90%, veyr fun so far, i am only using a 65hp shot but i am thinking of going to over 100 i just have to retard the timing about 12 degrees, so i will see how i like the car runnin like that. the kit was very reasonable to buy and install, about $450 for all parts and less than $200 for the young fellows at the honda garage to install it, jim
james madson


what changes have you had to make to the engine internals to support the extra HP? Have you replaced the standard crank / pistons / valve springs or are you running a fairly stock set-up?

Engine specs as follows on the new engine:
Built by Dan LaGrou of D&D Fabrications, Inc.

Displacement: 269
Bore: 3.530
Stroke: 3.4 (Buick 300 crankshaft)
Block: Olds Jetfire
Heads Olds -829
Piston: TRW2492-F
Deck Height: .000
Chamber Volume: 41cc
Compression Height: 1.580
Compression ratio: 10.3:1
Intake valve: 1.625
Exhaust Valve: 1.425
Valve Spring:D&D 813
Lifter:D&D 896
Camshaft: Crower 50232
Head gasket: .040 composite
Con Rod: Eagle EAGCRS570053D (5.70
Rings: Hastings 2M5650 +.030
Rocker Arms: Stock Olds 215
Pressure Plate:D&D360700
Clutch Disc:D&D26027

plus I just added a special built 6 quart baffeled oil pan (obtained through Dan at D&D as well) and he relocated the pick up further back.

I ran up to an 80 HP shot of Nitrous on a fairly stock (some head work and a crane cam and lifters and MSD distributor) 215 Olds before I had Dan build me this new stroker motor.

By the way my Nitrous system is a NOS Sportsman Fogger system and it is a wet system.
Michael S. Domanowski

Ok this is like my take of the Juice. It offers somewhat cheaper initial cost then the other forms of power adders. Average cost in the local area to have a bottle refilled is $3.45 per pound means a 10lb bottle will cost you $34.50 to have your bottle refilled. Now if you go through two bottles a week (lets be honest with our selves unless you spray the engine for the first time and scared the crap your self. It becomes addictive and you will quickly go through a bottle. [Average of eight to 10 passes per bottle]) Therefore, that is $69.00 a weekend (if you are anything like me). Racked up over five months you may be looking at as much as $1380.00 if you spray the engine. Back to what I am going to say wet kits a good for cerebrated engines. I would never use a wet kit on an EFI engine due to the risk of fuel pooling in the intake causing a nitrous explosion (which can and has happen for many people). Now you need a window switch, which only allows the nitrous to flow between certain rpms. Nothing like hitting the rev limiter and the crap pools in the cylinder causing cylinder damage. So do your home work when choosing a kit get all of the proper safety equipment and never run to big of a shot for what your engine can handle.

The fuel puddling effect is not due to a wet system, or dry system, it is improped set-up. This is also highly less likely in a V8 than a 4cyl. No offense to our little import buddies, but many of them are just slapping on parts and using the biggest thing they can without tuning it properly or looking at the long term issues. A window switch is a nice add, but not required. It basically acts as a fancy WOT switch, that uses the EFI's TPS sensor rather than mounting a new switch. They are really good for multistaged systems.

Bottle fills is the great forgotten piece of a NOS kit, no question about that. Guys up here say is roughly $40.00 for normal fill unless you know someone that can give you a deal. number of passes however is lower than 10, most guys saying 5-7 with a 100shot. Now up here is not doo bad as on busy days your only looking at 5 passes tops at the track for a full day. Either way though long term NOS is just as expensive as say a turbo or blower, and technically less usable since in many states it is illegal for use on the road.
Larry Embrey

So, Larry how many cars have you used nitrous oxide on? How many installs have you done? How many years of experience do you have with nitrous assisted motors?

I think you and I are in agreement basically, we just preffer different systems. A Properly installed and sized NOS system whether dry or wet will NOT harm a motor, period. SET-UP and proper sizing are KEY.

Each has up/downs, it really depends on what the end user wants and thier pocketbook/wallet can handle. EFI or carb makes little to no difference with regards to a wet kit. Dry is only possible with EFI unless it is a track car and the owner does not mind it running pig rich when not on the bottle.

I pretty much believe Wet is the way to go, it easier on fuel system, always has proper A/F balance, etc. Yes is more work, has it's own install issues and is more $$, but to me is worth it. The damage and problems I hear about are 90% of the time related to people blowing engine because of 1. Too much NOS for overall engine durability/components. and 2. A Dry kit that went lean because the stock fuel system could not maintain proper A/F ratio, often due to using to shot size bgger than the system could handle. Often times as a safety precaution with Dry kits, people will install bigger fuel pumps and injectors so that the system can adapt and provide the extra fuel when needed.

Lots to think about Benja, just take your time. I would HIGHLY recommend finding local racers and see what pro shops they recommend that are familiar and experienced with V8 carb'd and EFI nitrous installs. Then visit that shop and talk with them about your plans and goals. Also maybe hit a library, there have been a few books out there that are about nitrous installs, both the, science and parts aspects.
Larry Embrey

This thread was discussed between 26/06/2003 and 11/07/2003

MG MGB GT V8 Factory Originals Technical index

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