108 replies to this topic

[DaveCoxon]

Turbo charging the MPI would be the simpler ( not easy in relation to carb)of the injecton systems as you can use the original inlet swap out the throttle body for a turbo ( sealed unit, if there is actualy any difference other than it being alloy) off another Rover (almost like for like), pipe the discharge of the compressor through an RS intercooler going direct onto the throttle body. The MPI already has two injectors with others freely available in a veriety of cc/min to match the power, all the temp sensors are there, already has an oxygen sensor, all the wiring and relays are there and the direct fire distributorless ignition coil.

I personaly would use the Megasquirt engine management system as it is freely adaptable to almost every situation. Only one problem I see is the crank position sensor, I don't know if any one has coded the Megasquirt for Rovers unique pick up pattern. It would also be easy to fit a knock sensor. This along with the usual turbo required mods of course.

Big boost high power engines would require very big injectors in relation, causing difficulty in a single or twin injector system to control the low rpm fueling, so medium power increases would be much more succesful

cant see why it cant be done, but it certainly would not be as simple a carb turbo.

Realy got to get this sussed for my project, though I will be using four injectors with a single throttle, similar to below but not the same

EDIT: picture changed

ok a few points:

MPi inlet will not fit with turbo ex manifold.
MPi has one-bar map sensor. It will not see any boost, hence will not pull the ignition away. Also will not add more fuel as boost increases.
MPi injectors are already high-impedance 480cc/min items. Bear in mind that despite these, the MPi still has difficulty going over 66hp/litre.
MEMS is not mappable.

Someone has recently figured out the Rover (k-series at least) flywheel for MS
MS will still not perform 'correctly' (ie at 1000 rpm aswell as 7000rpm) on an A-series.

To get round the MPi issue, I'd have a second set of injectors fitted. Then, a 'piggyback injection controller for each MEMS injector channel, such that you can use the signal from the mems (so the second injector is triggering at the right time to prevent charge-stealing) and adjust the output of this injector to add the additional fuel.
You then will need a wasted-spark style (two channel) boost retard system to pull a few degrees off the MEMs advance as the boost builds.
A one-way check valve (eg 'missing link' as used by honda tuners) to prevent the map sensor seeing boost.

All pretty complex all in all!

A BMW or even 7-port head with MS would end up easier and cheaper probably!

[mini_me]

Well i value all your opinions, i know it will be very difficult to run a single injector on a turbocharged engine. I am determined to use a higher compression than standard. I don't believe that money will be well spent on the likes of a t2 conversion as im sure the higher cr and t3 will be as good. Iv decided to run the higher cr with t3 and about 4 psi of boost, afterall, more boost doesn't necessarily mean more power. I think alot of people are forgetting most jap cars (like the skyline) run only 4psi of boost with a cr much higher than that of the metro turbo. A high cr on a well set up turbo engine can prove just as good as running high boost it doesn't mean im going melt the block. With the right advance/retard dizzy, intercooler and higher ron fuel (thinking an octane boost and methanol mixture bout 105ron?) i think i can make it really reliable.

Thankyou again for your comments and suggestions! :grin:

[ditz]

correct me if im wrong here, but that fact about the skyline running high comp and low boost... isnt that true of many modern turbo engines??

and isnt it also true that when they go after big power from the skyline engine the CR is dropped down again and the boost wound up?

[wolfie]

skylines also a 6 pot 2.6 that pumps alot of exhaust gas into the turbo not a weezy 1.3 siemesed port a series that does not

cant see how you can use finer points of development of one with the other

[Sprocket]

ok a few points:

MPi inlet will not fit with turbo ex manifold.
MPi has one-bar map sensor. It will not see any boost, hence will not pull the ignition away. Also will not add more fuel as boost increases.
MPi injectors are already high-impedance 480cc/min items. Bear in mind that despite these, the MPi still has difficulty going over 66hp/litre.
MEMS is not mappable.

Someone has recently figured out the Rover (k-series at least) flywheel for MS
MS will still not perform 'correctly' (ie at 1000 rpm aswell as 7000rpm) on an A-series.

To get round the MPi issue, I'd have a second set of injectors fitted. Then, a 'piggyback injection controller for each MEMS injector channel, such that you can use the signal from the mems (so the second injector is triggering at the right time to prevent charge-stealing) and adjust the output of this injector to add the additional fuel.
You then will need a wasted-spark style (two channel) boost retard system to pull a few degrees off the MEMs advance as the boost builds.
A one-way check valve (eg 'missing link' as used by honda tuners) to prevent the map sensor seeing boost.

All pretty complex all in all!

A BMW or even 7-port head with MS would end up easier and cheaper probably!

Don't get me wrong.

Maybe I gave you the wrong impression, but i would not consider trying to use the MEMS ECU, I did not mention it. Getting round the crank sensor issue is easy by using the KAD crank sensor kit. A 2bar Map sensor is fitted inside MS ECU. You say the MPI injectors are 480cc/min ( I certinly don't know) which equates to 96 HP each ( plenty of squirt for 180hp), as for the MPI struggling beyond 66hp/litre normaly aspirated, i can only put this down to a restriction in air flow and or the ECU and these would change any way with the MS and Turbo. I was under the impression that it was the injectors that ran out of squirt rather than the engine running out of puff at 90 bhp, something does not seem right. What is the 0280 number of the injectors?

I was also under the impression that MS could run 1, 2, 4, 6 or 8 high or low impeadance injectors. I don't understand why it wont work under 1000 or over 7000rpm with two injectors, but then why would you run a street turbo over 7000rpm anyway. The MEMS seems to work below 1000rpm with two injectors why not the MS.

I'll need to read up on the latest developments of MS me thinks.

As for the exhaust manifold, again I never mentioned the use of the standard turbo manifold. A custom manifold with a Garrett T2 or even an IHI tucked close to the back of the engine, much like the mirage T2 kit. Not only this but the engine sits a little further forward on the Injection cars giving a little more space at the back.

No disrespect mate, I'm just a little confused as always.

[Sprocket]

Well i value all your opinions, i know it will be very difficult to run a single injector on a turbocharged engine. I am determined to use a higher compression than standard. I don't believe that money will be well spent on the likes of a t2 conversion as im sure the higher cr and t3 will be as good. Iv decided to run the higher cr with t3 and about 4 psi of boost, afterall, more boost doesn't necessarily mean more power. I think alot of people are forgetting most jap cars (like the skyline) run only 4psi of boost with a cr much higher than that of the metro turbo. A high cr on a well set up turbo engine can prove just as good as running high boost it doesn't mean im going melt the block. With the right advance/retard dizzy, intercooler and higher ron fuel (thinking an octane boost and methanol mixture bout 105ron?) i think i can make it really reliable.

Thankyou again for your comments and suggestions! :grin:

Are we also not forgetting that these 'Jap' cars with only 4psi boost and high CR's are using a massive intercooler, where the standard Metro is designed for a 7psi boost without intercooler.

Use gas laws and work out the charge temp when at the point of ignition and they will probibly be very similar.

[DaveCoxon]

MPi runs out of injector - I guarantee it.

You can't simply get enough fuel in there with the very short injection window on the inner cylinders. Put a wilder cam in there, and the window reduces again.

http://www.turbomini...p?p=vt&tid=6485
http://www.turbomini...php?p=vf&fid=29

Pretty much covers the injection issue wrt to 'turbo' A-series.
I'll be getting my injectors soon, my injector test bench and contoller will be done over christmas, then the manifold started... Hopefully all in and done by april (well, that's the plan!!!)

[DaveCoxon]

Back to this high cr shenanigans; Don't the majority of real high-power jap import motors pink their tits off on UK fuel???

These also have super-efficient management systems, with individual cylinder adjustments for spark. And a sequential injection system, giving a homogenus mixture and allowing for exceedingly accurate control of each cylinder.

And you're going to use an SU and a single 'heath robinson' injector and get the same results on a siamesed inlet engine which by it's nature always runs righer on the outer cylinders even when perfectly set-up.

All you've got to do to proclaim it's a success is pull shed loads of retard as the boost starts to build to stop it pinking; hell - pull enough and you'll throw 10+psi in there. Not pissing on your fire - but if that's what you want to do - then crack on.

Why not just drop it to 10:1 at the very least - give yourself a half-fighting chance?

[mini_me]

So surely if the metro turbo will run 7psi of boost on 9.4:1 with no intercooler, i will be able to run 4 psi safely on 10:1 with an intercooler and a higher ron fuel. Im sure 103 ron can be achieved with uk fuel works out bout £6 a gallon. So really the only problem im getting stuck with, is the fact that i might not be able to pull the retard back far enough?

Also so iv been told with skylines they should be set up to run on uk fuel and i know theres a little wiring trick that you can do to get it to 7psi but any more than that and you've got to start spending money on the engine. I know that these engines are on completely different scales, but surely the same principles apply?

Iv also started working the chambers on a spare turbo head of mine, iv go the cr down to 8.1:1 with that head. The reason im thinking of a higher cr, is an on going arguement with a mate from another garage down the road. He still stands by the fact that it'll work! Im still torn on the two decisions!????

Cheers! :grin:

[Oldskoolbaby]

Not 100% sure of this but Im sure that the modern WRC teams run the standard C/r that the model originaly had in production. And Ive heard that the big Jap tuners are starting to run higher c/rs. Norris Designs for example quoted in this months sh1tty maxpower that low c/r are in the past. These boys run 750bhp+ 2.2 litre engines so they know thier stuff.
There are ways to do this but Im 100% sure you will not make it reliable doing this with a carb. The fuel settings will have to be spot in these situations and how are you going to get this with the ammount of variables there are while driving.(air temperature, air pressure, differences in petrol)
Looking at modern day technoledgy says it all. The new M5 for example monitors every exhast port for different mixtures and corrects them accordingly. This bassicaly means that every cylinder has exactly the right mix. Its technoledgy like this that means modern engines can do things that are otherwise considered dangerous to the old basic carb, points and distributer.
Im only ever going to turbo my 7 port once I have the right ecu etc.

[DaveCoxon]

At 4psi - it's barel;y worth fitting an intercooler... max intake temps you'll see is 50 degrees or so. An ideal target is 40 degrees - but anything under this has so little benefit you'll barely notice it.

As stated; a skyline isn't on a SU carb. Nor, does it have siamesed intakes which by virtue of their design, always mean the inner cylinders run richer than the outers... Keep it simple. If you're determined to raise the CR, then do so. But keep it at 10:1 and see how that goes.

[MRA]

Not 100% sure of this but Im sure that the modern WRC teams run the standard C/r that the model originaly had in production. And Ive heard that the big Jap tuners are starting to run higher c/rs. Norris Designs for example quoted in this months sh1tty maxpower that low c/r are in the past. These boys run 750bhp+ 2.2 litre engines so they know thier stuff.
There are ways to do this but Im 100% sure you will not make it reliable doing this with a carb. The fuel settings will have to be spot in these situations and how are you going to get this with the ammount of variables there are while driving.(air temperature, air pressure, differences in petrol)
Looking at modern day technoledgy says it all. The new M5 for example monitors every exhast port for different mixtures and corrects them accordingly. This bassicaly means that every cylinder has exactly the right mix. Its technoledgy like this that means modern engines can do things that are otherwise considered dangerous to the old basic carb, points and distributer.
Im only ever going to turbo my 7 port once I have the right ecu etc.

A disadvantage of quite a few turbo engined cars is boost lag -

The lower the CR the more lag you get. Obviously there are ways around this. however if we just ignore them for this instance then it follows that the higher CR and lower boost will give a potentially more driveable car, for sure it won't be a rocket 13's 1/4mile contender but it will non the less be more driveable.

Nothing is 100% efficient - if you use the 3psi is approximately equal to 1CR

Then if you start with 10.5:1 NA and turbo it to 4psi then your effective CR is now 11.8:1, as long as you can control the ignition properly with a decent ECU and you have a well built engine with good components i.e. Omegas, JE's etc then this could give you good results.

However what would it give you over say a well built 1380 NA engine or is this what you would be considering as your core unit ???

Why do these specialist tuners use an intercooler on 4psi ?? Is it simply a commercial reason (because the customer wants it !!!) or maybe its down to any advantage is beneficial !!!

A charge cooler would be more benificial but only if using its own water supply, pump and rad, but then again this adds a lot more weight.........

The good old SU whilst not state of the art is pretty good, invariably its the engine that goes out of tune and not the carb (su)

The old adage is biuld it then modify it one step at a time to "see" where your improvemnts are coming from or not as the case may be....

[mini_me]

Very wise words, thanks for not totally writing off the idea that high cr is a deffo no no! Im sure a good tuner with a good set of det cans and all round good equipment will be able to set the engine to run safely and efficiently. The reason i thought that the higher cr would be a fairly decent idea, is because it produces a much more drivable car. I have really been put off now tho. My standard turbo runs great, but off boost its real sluggish. It makes city driving so boring! Gonna have a re-think! Again!

Cheers! :grin:

[Oldskoolbaby]

The good old SU whilst not state of the art is pretty good, invariably its the engine that goes out of tune and not the carb (su)

I agree, but in this situation where the fueling has to be exact the carb is never going to be good enough. It wont adjust when the air temperture rises and falls. Driving the motor around slowly ie around town, the under bonnet temperature will obviously increase and once up to speed and more cool air is flowing through the bay it will decrease. This will mean that the mix will just never be perfect. In my opinion, I would only ever use a high C/r and turbo on an 8 port or kad/Jack Knight16v where each outlet can be assesed and changed by the ECU and injectors to suit. There is just not enough control with a carb.

Just a quick question Mini_me, are you looking for some high out puts or are you looking at just drivability? If you want to have a high output and good drivability, why dont you consider supercharger?

[mini_me]

Really lookin for good drivability, thought bout the supercharger but decided on the turbo. I still think it will be capable of producing 100bhp, which is more than enough in a mini, without going to wild. Have owned fez rst, clio 16v etc but even in my 153bhp rs i couldn,t stay with a bog standard mini turbo!


Cheers! :grin: