7 port injection vs 5 port injection both turbo..
Turbo Mini Forums

which would give a better engine in terms of how easy it would be to set up?
the 5 port would be a spi turbo (think specialist components spi kit) and the 7 port would have itb's with a plemum on the front.. assuming all components are kept as equivilents or the same, such as cam shaft ECU and Throttle bodys (as close as possible for tb's).
basicly i want to know is the 7 port worth the extra money and setting up if its not going to give that much extra power

p.s. the engine is a 1293T with a GT17 turbo built as a road legal race car (track slag in other words..)

masive masive masive can of worms mate

in my opinion the spi injection method is a big bodge plain and simple its adequate enough for n/a but there is no control over the fuel distribution per cylinder ( big problem on the a series) and thats crucial

for the 7 port, tuning will be the same give or take a little but the results will be as close to perfect as you could map, fuel distribution should be equal as a result should be more powerful reliable and able to tune close to the limit

one mini to look at is wil h and ben h 's 7 port 998 turbo ( they went from 5 to 7 port this year with fantastic results)

Yes i moved to the darkside

Instagram @jdm_brett

As Brett says I built a 7-port turbo, but interestingly, I also built a SPi turbo.

The results are that the 7-port is superior in eveery way. It was also a lot easier to set up. However, that had something to do with wanting a more refined map for the Spi setup and the MS1 is a pain for some things, especially light throttle settings.

It depends what you want, if you are after a modest amount of power, the SPi is more than up to the job. If you want 200bhp AND injection, 7-port is a good choice.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

so for a modest day to day turbo/fun weekend country driver the SPI would be adaquate?

This is what I said on the subject last month:

"You need to go back about 5 years to the point where the TM forum started discussing the merits of wet manifold or port injection.

The concensus at the time was that the potential lean condition on the outer cylinders due to poor mixture distribution of a wet manifold in conjunction with a turbo would have serious implications for engine life i.e. blown head gaskets, burnt valves or even holed pistons. "

For all means try the SPi, but be aware of the potential risks.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

sorry for thread hijacking to a degree, but the sc kit in this instance i assume is an upgrade on the carb or yes but not really significant enough to measure in reality?

Depends on your criteria for what constitutes an upgrade.

Edited by Paul S on 17th Oct, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Schrödinger's cat - so which one am I ???

Yes, someone needs to measure it.

But equally, there is enough miles on SPi cars running turbos to state that it is not an engine melter.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

I've no doubt that an SPi turbo can be setup safe i.e. rich and conservative timing, but then you end up with less power and driveability than a carb.

Rather defeats the object in my opinion.

Come on wil, fit a couple of widebands to yours so that we can put this arguement to bed once and for all.

Edited by Paul S on 17th Oct, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I bought a 7 port because i am a dipshit when it comes to injection and the 7 port in theory is the easiest option

sorry for being a bit thick here in this convo but one thing im trying to understand is why (if what i read correct) the afr's would be so different between a SPi (or MPi if that is what the sc kit is being it has 2 injectors) and a carb?

in my simple head the fuel sits in the float bowl gets sucked up the jet into the engine. on an SPi or MPi it just gets squited in there.

unless your specifically talking about having 1 injector in which case i can kinda see why it might cause issues.

again sorry if this really does seem like a dumb ass q

Edited by t@z on 17th Oct, 2011.

http://www.jbperf.com/

Then there is the phenomena of "wall wetting" that delivers approx. 20% more fuel to the inner cylinders.

The fuel that is in the air in the port when flow stops as the outer cylinder inlet valve closes sticks to the port walls, then gets sucked of the port wall when the inner cylinder inlet valve opens on the next cycle.

So even if you do inject with 4 identical pulses per cycle, it will still be distributed unevenly.

Edited by Paul S on 17th Oct, 2011.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

And this wall wetting is partly why sequential port injection can provide significantly better results because port injection reduces the wall wetting by putting the fuel charge closer to the cylinder (less wall to wet) and sequential injection allows you to adjust fueling independently to each cylinder to offset any remaining wall wetting contribution.

Jean

http://www.jbperf.com/

I agree with the theory, but my car is as driveable as the carb, and I run the same ignition map. I don't run it especially rich either. although owing to other issues it's still not as fuel efficient as I made the old green mini engine, but as good as the carb was on the Sprint.

It's not perfect and I'm still fiddling, but the carb was never perfect either, far from it. Not sure about power, seems the same and ran what I'd expect at Avon with the power that the old carb had.

If I had the money and time I would happily fit twin widebands, I'm as interested as everyone to see the results. but I have neither at the moment.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

looks like the basic concenses is that it depends on application.. if the car/engine is not built for absolute power then the spi will do if its built to squeeze every bit of power then 7 port is the way forward (or even 8 port but i spose thats the same when it comes to intake/injection mapping?)

oh.. slightly off topic but wil h, whats involved with putting a 7 port on a 998.. does the head need modding or the block or both for things such as valve clearences or is ur head a special 998 7 port casting??

Edited by black n yellow on 18th Oct, 2011.

The mods are basically the same for fitting a 12G940. Pocket the block and fit a 1275 head gasket.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

Would say over the carb it is a more refined beast though?

I know this is not the argument but I wanted something smoother and reliable.

Most spi run pretty smooth but not a power house compared to single carb.

And for me that's partly the idea of a injection kit and reliability, I got the shits of fiddling with my carbs even when rebuilt i was never quite happy until I whent to a single the cold starts shitted me out mega jolt in, was very happy but it"s halfway to injection so why not go the full way.

i think if you want all out power then 7 port is the way, the scoot is nice I'll be setting mine up NA once I get the car back together.

But I'll be running a supercharged set up, I think this is fine because the charger kicks the shit out of the fuel before it makes it"s way in.

Edited by NickG on 18th Oct, 2011.

I said it was a can of worms

Yes i moved to the darkside

Instagram @jdm_brett

interesting can of worms though, i'd thought becuase the EFI was more modern that it would have better gains and it does to a degree on maybe reliability.

i was going to get a sc kit next year maybe but now i think i might just stick with me carb until i can afford...decide to get a 7 port head.

Edited by t@z on 18th Oct, 2011.

Or you could try the TM developed 5 Port port injection setup of which there is a whole section of this forum devoted to :)

Runs and hides.......

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

I don't see why you should run and hide. The potential for a well designed 5-port EFI setup should be very close to an equally well designed 7-port.

And it might be easier to package an optimal setup with a 5-port head and I don't think anyone has done the research and experimentation to come up with an optimal setup for a 7-port head.

But maybe I'm the one who should run and hide because not many seem to want to hear that.

Jean

Edited by jbelanger on 18th Oct, 2011.

http://www.jbperf.com/