Engine swap or serious upgrade

[James Doulton]

It was all Paul Sheridan's fault by talking about 500bhp engines in Astras, not that I can afford such a beast nor that I think that it would make a lot of sense in a Dutton. However, I am thinking about ways to add power to my Legerra.

What I'd like would be to fit a Vauxhall V6 from an Omega but there is no way that it would fit - there is a reason for that huge bonnet on the Omega! The Legerra engine compartment is rather snug. A Rover V8 is much too long and a bit too wide, an Essex V6 is too wide (and heavy), most modern V6's are much bulkier because of all of the overhead cams etc.

I have thought about going down the Zetec route, looking at the engines that Omex offered, although they have now moved on to Duratec. Both of those engines have the coil pack and water housing at the back of the engine where it wouldn't fit against the Legerra body. Plus it is not cheap, at £7700! Also I am not sure whether an engine needs to have the emission paraphernalia appropriate for its date of manufacture.

All of that leads me back to my Pinto. I don't want to spend a fortune on making it rev to 8000 rpm and I want it to remain easy to drive in any gear, rather than having something temperamental and lumpy. So I think that it only leaves 3 options: supercharger, turbocharger or nitrous oxide injection.

As far as I can see, all modern superchargers and turbochargers are designed for dry air, i.e. the pumped air is fuel-free, this affects the internal design and they don't expect to have a vacuum which would suck the oil out of their bearings. Therefore I'd either need a blow-through carburettor, which are rare, or I'd need fuel injection.

I've seen suitable superchargers on ebay from small Mercedes but they are not simple and expect electronic control of the clutch in their drive pulley. I prefer the turbo option as it is less challenging mechanically and as far as I can see the TD04-14T from a Volve V40 (200bhp) looks a pretty good fit with a wastegate set at 0.7 bar - that should give me a 60-70bhp increase. However, it would need fuel injection, and that is a considerable extra cost when there is no guarantee that the project will work.

The only 'simple' option is N20, which could be done by adding an injector below my existing carburettor - the carb need never know about it! From what I can see N20 should be good for about 50-60bhp extra without making any real changes to the engine. I have been reading up on it in a book that I bought and on the net, particularly www.nitros.info which was created by a guy calling himself burgerman. He made up systems himself and seems to think that I could make a home made system (for less than £200) that is superior to the systems that I could buy for £900. I am rather inclined to believe him as I cannot see why the kits are so dear. I am thinking seriously about doing that.

[Adrian Southgate]

If it was anyone else James I would be thinking 'yeah right' ... I'm worried that you're actually planning a NOS install on a pinto...

By the way, the essex and cologne V6's fit, its been done, there was one for sale two weeks ago on ebay with a 3.0 in it...

[Dave Thomas]

I've always been led to believe that putting nitrous on a standard built engine would just destroy it, 

[James Doulton]

That pinkish one is still a 'project' and has failed to sell a few times so maybe the install didn't work out.

[James Doulton]

Okay, so I have now got a rather nice Essex V6 in my garage. Now how do I connect it to the back wheels? I currently have a Type 9 gearbox, so I could get a bell housing from Burtons which is rather expensive but will presumably let me keep my cable operated clutch and all the rest of my drive train.

Alternatively, I can look for a Type 5, which is only a 4 speed and is slightly different length, I think. It might be possible to reposition the engine and gearbox to keep the same propshaft as I'm pretty sure that the V6 is shorter than the Pinto. I already have a 3.54 diff waiting to go in too. Maybe I'll fit some big wheels to improve the gearing.

I have weighed the V6 and was surprised that it is 'only' 187 Kg, without the starter (which I need to get). So that is only about 50Kg more than the Pinto. I'll have to keep a spare wheel in the boot to balance the car!

[Paul Sheridan]

NOS is easy to retro fit, bur unless you do some serious mods to the engine, the pressure in the cylinders when you decide to push the button, will do untold damage! 

A standard Z20LET engine from a turbo astra will give you about 200bhp and if you treat the turbo with respect will be very reliable,   

[James Doulton]

With an added turbo the pressure throughout the cycle is higher and the temperatures are all higher too compared to a normally aspirated engine. That is not the case with Nitrous Oxide injection because the way that you get all of the existing air, plus the extra N20, into the engine is by the huge cooling effect of the evaporation of the Nitrous. Comparing 8-10psi turbo (with intercooler) to Nitrous to get a 50% power increase, then the charge density is about the same in both cases but the temperature with Nitrous is about 100C lower than the normally aspirated engine, not higher like the turbo (even with an intercooler). This means that the compression pressure is similar to the normal engine (actually 10% lower) and the temperature is now more than 200C lower.

Ignition pushes the pressure up to considerably more (35% more) than the normal engine but this can be offset by retarding the ignition so that it ignites later, as the piston starts to fall. The pressure throughout the power stroke is 40-50% higher than the normally aspirated engine but the temperatures are still a little lower. The turbo is similar except that the temperatures are much higher throughout.

The cooler temperatures, coupled with the anti-knock properties of N2O, means that there is less risk once the system is set up. Compared with the equivalent 50% power increase with a turbo, the Nitrous is gentler on the engine. It is also cheaper initially but the running costs will be higher - I haven't found out how much it costs to get a Nitrous Oxide refill.

What's not to like? Okay, it still needs a controller to either adjust the dose at low revs or to cut it out entirely below 4000rpm, and a variable spark timing, and sensors to avoid very lean mixtures if the supplementary fuel supply fails. Then you must remember not to use it when you are going around a corner, or in the wet. And sod's law says that it'll run out just when you really want it and your local supplier will have shut for annual holidays...

[Adrian Southgate]

I still think N2O is too 'heavy duty' for anything other than racing in a straight line. You really don't want it cutting in on a wet corner.

[James Doulton]

A £200 Nitrous system, when armed, is controlled by a simple switch on the throttle pedal so that when the pedal is to the metal then a fixed supply of Nitrous Oxide and fuel is added. There are drawbacks to this in that the dose is completely 'blind' and is not affected by engine speed. So it is not sensible to use it below about 3,500-4,000 rpm or else you get too much Nitrous per combustion cycle and could wreck the engine. Also the sudden injection of 50% extra torque could unsettle the car unless it is going in a straight line.

To my mind a Nitrous system needs to have some sort of control - at least some way to inhibit the system at low revs. Also I don't think that the simple one size dose makes a lot of sense as it adds a lot more torque at lower revs than at high revs, I think that the supply should be revs dependent using pulse-width controlled solenoids, like fuel injection does. Also I just don't need N2O in first gear as I can spin the wheels (or one wheel) already. So it is starting to sound like this will end up as more of an electronics project, like my rev counter. My plan would be under WOT to start the nitrous supply at 2500 rpm and to increase the added torque linearly up to a maximum at 4000 rpm and then hold that torque to 5500 rpm and drop it to zero added linearly by 6500 rpm. If I floor it when already in the 'boost band' then maybe I should phase in the boost over half a second or so, but cut it instantly if I come off WOT.

[Adrian Southgate]

The alternative would be staged multiport, a carb base plate using small bore injectors to give 'just a squirt' followed by a second 'full burn' set using direct injection into the manifold right by the head. Actuators to be pedal controlled with a separate arming switch so you have full use of the carb under 'normal' running or electrolnically controlled so you can map them into the dizzy vacumn advance mechanism too.

[Dave Adams]

James i am in the process of fitting the zetec with standard ecu to my Legerra. the coil pack unbolts and will not present a problem in moving it, the bulkhead is easily modified in any case should it be necessary.

the zetec is a smaller engine in height and length than the Pinto (about 3" in both dimensions)  and weighs about 20kg less. it will fit onto your existing gearbox and the sump is barely lower than the gear box bell housing, so ground clearance is not compromised  

my local scrapyard will supply engines for £140......a cheap Mondeo is only £250 or so and everything you need for the engine is easily removed (fuel pump, wiring, ign key with PATS sensor, ECU......etc)

[James Doulton]

Presumably a Zetec needs to have a catalytic converter and to pass the more stringent emission test when it is MOT'ed.

[Dave Adams]

NOPE

the test is done on the age of the vehicle not the engine.....

although it is a good idea to keep the Lambda probe for the ECU to work better