The Sleeper Project, why ?
OK, I think we're all familiar with the concept of a sleeper, or Q car, looks stock externally, but has some major modifications under the bonnet, with little or nothing to hint at what lies beneath, that's the main aim for me, maximum Q
The car :
For the project I purchased a mint, fully historied 1987 325I Se 2 door in Zinnobar red, not my 1st choice of colour , but a car this solid, with the history to back up the condition, sometimes you just have to live with it ( its grown on me over time , not dolphin grey though is it )
As I knew full well what I had in store for the SE ( nicknamed granddad BTW ) I uprated the brakes and suspension before setting about the main point of interest, more power
Modifications:
The engine was superb having had a crated BMW replacement in 1995, and having covered 30K since then, so nothing to do there then, result!
Being a Cat ready engine, the compression ratio was fairly low to start with , so I decided to just turbo the beast as it was, and uprate anything that failed later, to this date there have been no issues with the install in over 10K miles ( touches wood)
The turbo install:
My aims were to create something that was almost factory in appearance and which drove without any lag or massive jumps in power, smooth and silky , to compliment the BMW engine in a way not seen previously, with masses of midrange torque in exchange for sky high BHP figures
Yes there are mega power 325i turbos in the US and Sweden, but as this is my daily driver 500 bhp was not the aim, if I'm honest 300 bhp was the goal I set myself.
The turbo I chose was donated by a 2wd-sierra cosworth, it's a stock T3 with a 0.50A/R on the intake, and 0.47A/R on the turbine, in English that means its quite small, and should deliver lag free boost, nice! The unit was duly rebuilt an received a few internal mods to help with its new location
The manifold was in fact from a rare BBR kit produced in 1991, it's a log type manifold and very compact in design, although originally BBR used a smaller T2.5 turbo, the T3 was more available,more capable and bigger and as they share the same input flange,would bolt straight on without issue.
To get oil in and out of the Turbo, a feed was taken from the oil pressure switch, and a drain added to the upper portion of the sump, perfect, the turbo is installed, now what?
The intercooler story :
Why do I need one, well as pressure increases so does temperature, the downside is air density drops , not good for power hence the need for an intercooler to cool the engine intake charge down again
My 1st choice was a 2WD cosworth intercooler, compact but very efficient, and obviously a good match for the turbo, a unit was procured and I set about fitting it in…..
In short, the IC didn't fit !, it would if I cut the front valance out, but that's giving the game away, a soloution had to be found, and fast
A chance visit to a breakers threw up an alternative unit, From a Volvo, it had the inlet and outlet where I needed them, and was the same size as the stock BMW rad and very slimline, Result, the IC was purchased and cleaned up ready to install.
With the IC installed between the rad and front panel, no external signs of what lay beneath were evident, perfect for the Q car
So we have a turbo and intercooler installed, now to join them together.
I selected to run 52mm charge pipes, some 4 metres in total were procured and with some deft cutting and welding, shaped to fit the confines of the engine bay.
We are now officially turbocharged! Great, but it throws up another issue …..
How to fuel the car :
Ok, I knew this to be an issue from the outset, there's simply no way for the stock ECU to see the boost, and flow enough fuel to prevent a lean condition, a soloution had to be found, and fast, I wanted to drive the Sleeper
Standalones:
OK, big word, what's it mean, in simple terms it's a replacement ECU with more capabilities and flexability than the original, for this project I looked at many , most were over a thousand pounds and would require a lot of tuning on a dyno ( expensive) to get right, oh dear, another possible hitch in my plans.
An alternative is an FMU typically, this replaces the stock fuel pressure regulator, and when the engine goes into positive pressure (boost),the force acting on the FMU causes the fuel pressure to rise, thus increasing flow, A cheap solution yes, but I wanted a car that drove as good as BMW intended, the FMU was not an option.
Megasquirt:
This is the standalone ECU I chose, after almost a month reading up on various ECU's, I chanced upon the Megasquirt main site, looked good, capable and cost effective, in short just what I was looking for.
I'm not going to cover the tech specs in much detail here, but with an onboard MAP sensor there were obvious advantages to the unit, so I duly purchased one and set about fitting it
I could wax lyrical all day about the ECU itself, but in short it's reliable and capable , not state of the art in terms of spec, but more than good enough for my install, and because of the open source design, easily modified to perform many more tasks than originally intended, with no downside
The install:
1st step is the loom, you have 2 choices, add a new one and disconnect the old, or splice the new ECU connector into the stock loom and proceed that way, either is fine , however its important that all connections are good, and sheilded where applicable.
Looks bad doesn't it ! its not to be honest, the supplied wiring diagram for the Megasquirt shows where each wire need to be routed, and by using the BMW diagrams, each is soon connected to its desired location.
Once loomed and tested fully with a multimeter, its time to fit the ECU itself
The ECU is plugged in and ignition switched on, time to hook up the laptop and see if the blood sweat and tears I shed were worth it ….
Result ! all seems to be working as intended, I got the screen up showing engine speed temp etc and all was displayed in the correct sense
Time to turn the key and see what happens !
The starter churns and the engine coughs and splutters……. Finally it catches and bursts into life, to immediately splutter to silence again, better than I'd hoped for to be honest, and nothing less than amazing considering mere hours before the loom was a mass of spaghetti.
Time for a cuppa and to reflect upon how far I've come, now for me the best part tuning the car for optimum performance and reliability
Again I wont cover this in much detail, but suffice to say, unless you have access to a wideband air/fuel ratio tester, this stage will be almost impossible and very frustrating to complete , you can however get the car to run quite well at idle using only the engine vacuum indication on the screen , lowest vacuum is normally the strongest idle, in the case study we have here, the M20 engine has best idle around 35 Kpa
Once happy with the idle ( better than stock BTW ) and with the laptop and Wideband hooked up ,. Its time for a slow drive !
Oh dear, a lot of work to do, the car is lean everywhere and the injectors are maxed out already, time for some larger units to be fitted then I had suspected this may well be the case
After some research in the US, I opted for some 42lb/hr injectors quite a jump from the stock 14.3lb/hr units and to some extent overkill in this application, however the Megasquirt ECU allows any injector to be used so in they went.
After “ rescalingâ€a the injector flow in the Megasquirt tuning screens, a second test drive was carried out, much better air to fuel ratios, far from perfect but we're finally getting there folks !
After a day or two spent driving slowly around, building a fuel map to keep the engine running in top condition, it was time to try some boost.
Boosted 1st drive:
Below is a quote pulled from a forum I moderate on, www.e30zone.co.uk I have taken it straight off the screen as it reflects the moment perfectly
“Well, light greens are in, boost is @ 4.5 psi ( for now)
ventured out for a short test drive, set the AFR to 12:1 so its rich as hell but safe as houses, only tickled the loud pedal , no higher than 3K rpms.
verdict ?
grunt like a 750I , effortless cruising on little or no throttle, pulls 5th @40mph ( 1.6K) without a blip, must admit I am stoked
found the boost comes in @ 1.8K with load, I got some very strange looks from a group O lads @ a bus stop, dunno what they actually said but it sure looked like " dump valve , WTF !!!!?? ** , those aint turbo"
next step is test drive with co pilot so I can tune the VE tables, then I'm upping the boost to 7 psi there's enough fuel capability for 40 psi without any danger of going over 100% PWM, never going that high but 12-15 would be the main aims, depends on the intake temps, saw ambient +/- 2 degrees on the short drive today.
Gas bench agrees with the on board 02 so @ least I know I'm sound there.â€a
As you can see, I was quite pleased
Fresh from the success of the 1st drive, I used the Megasquirt's datalogging function to see where improvements could be made, there were plenty trust me, but I proved the concept and with some more tuning over the following days, with incremental boost increases, I was ready for someone else's opinion on the car, cue my Friend Salman, and his expert analysis
Again quoted from e30zone
“5.5 Psi and had a drive yesterday on my own.
The power delivery is enough to scare my 3.8 M5 - I'm sure it will be faster once boost is turned up.
The level of refinement is unreal, the idle is better than stock. Simply fantastic.
If you're thinking about going turbo do not hesitate!â€a
He's not easily pleased so the above quote can only be a glowing recommendation, Using Sal to drive and with me on the laptop,we soon had all the issues ironed out, the car had become exactly what I wanted, and drove like the maker intended, smooth and silky with approximately 50% more power to boot.
Summary:
OK, my aims were to created a sleeper/Q car.Been there done that, along the way many lessons have been learned, the chief one being you can achieve your goals, but forethought and planning are key to the overall success of the undertaking, willingness to compromise in certain areas helps too
Indeed there were some compromises on this project, mainly down to a lack of space but we got there in the end, and I stand by what I achieved.
What next?
As with all these things, I'm writing today in retrospect, it all seems a long time ago, it isn't but the memories are fading, hence this prose.
From the inception of this project to its conclusion I have honed many skills, indeed a spin-off from the project is I have carried out a number of commercial Megasquirt installs, including all the hardware building, wiring and tuning, and another e30 turbo conversion, all of which have been well received by those that commissioned them.
I've found that in the pursuit of perfection I've actually remapped my ECU 67 times since the original basemap went in, its true there was nothing “wrong “with it from the outset but each time a tiny change resulted in more power , lower emissions or better economy, all data I collect goes back into my fast growing map collection for use on later projects.
One thing I have noticed is mapping can be very subjective, some customers expect a linear power delivery, others a top end rush, the reality is anything is possible with different mapping styles, another case for horses for courses maybe ? whatever the case, that's why I feel its important to establish what the customer wants, and needs before commencing an install
You could say I've become addicted to tuning, I have to agree but that's the real beauty of the ECU, you can change things whenever you need or want to, bigger engine,new exhaust sytem, sporty cam profile, throttle bodies all no problem, just retune the existing map to optimise it for the new parts you added, Megasquirt is not only for those planning major engine mods, you'd be surprised how much an air filter can affect the overall tune of the vehicle, this is what brought me to Megasquirt in the 1st place, it gave me the ability to step outside the limits of chip tuning and really exploit the engines full potential .
Email FTW
What a great read!
