65 replies to this topic

[sonikk4]

Mmm that means mine will be the same then. Well not a lot I can do at the moment but when I get home I will have to dig the head out and have a look.

[Mini_Martin]

I measured between the 2 end exhaust ports (ignoring the middle port) on the billet head. From the inside edge closest to the middle, to, inside edge and got 280mm.

And when measuring from the same 2 ports on the exhaust manifold I got 274mm.

Sonikk I would be really interested to know if we have the same measurements.

I am asking around at the moment to see if there is a fix for this problem.

[Mini_Martin]

Ok guys so the latest status is all good so far!

The 220cc injectors are fitted, with connection adaptor (EV1 Male to EV6 female).

Valve clearances set at 0.020" hot, and she's running better than she has done in a long time. Idle is much better, start goes to idle much quicker without support, and AFR values fluctuate far far less!! Maybe a flicker of 0.1 or 0.2 rather than 0.6 to 0.8 at Idle.

I kept my own same map for ignition, and had quite a bit of re-ballancing of the fuelling maps. Low TPS values were almost a straight multiplication factor of the existing fuel pulses 1.5 to 1.7 High TPS values took a bit more work but were nearer a 1.9 to 2.0 multiplication factor.

Its early days yet, however all the signs so far are looking pretty good, and pretty soon I'll book her in for a Rolling Road. Prior to getting this far, I think I would have been wasting good money by it not being 'sound' enough for a RR to get the best out of it.

Tomorrow I'll restart her from cold and plot some cold start correction values too.

If anyone has a similar set up or faces similar problem, I hope that the above helps!!

[Mini_Martin]

Did you get the car back on the rollers?
What was the outcome, did it idle better?
And did the smaller injectors affected peek power?

I only ask as my elf had it’s first start up the other week and is really lumpy above ideal (is underivable). I only have the bace map in and know nothing about tuning... well the only thing I know is don’t blow your engine!! I was planning on taking a smaller sets of injectors with me to the rollers. If we struggled with the 440cc injectors just throw the 220cc’s in there.

[sonscar]

Not Mini related but my 1860 MGB has four 220 cc injectors and reaches 75% duty cycle occasionally.440 may be too large to deliver reliable fueling at lower pulsewidths.Don't shoot me I am a blacksmith.Steve..

[sonikk4]

I measured between the 2 end exhaust ports (ignoring the middle port) on the billet head. From the inside edge closest to the middle, to, inside edge and got 280mm.

And when measuring from the same 2 ports on the exhaust manifold I got 274mm.

Sonikk I would be really interested to know if we have the same measurements.

I am asking around at the moment to see if there is a fix for this problem.

Sorry never got round to checking this out, some things got in the way this year if I get a chance I will try and have a look.

[sonikk4]

Did you get the car back on the rollers?
What was the outcome, did it idle better?
And did the smaller injectors affected peek power?

I only ask as my elf had it’s first start up the other week and is really lumpy above ideal (is underivable). I only have the bace map in and know nothing about tuning... well the only thing I know is don’t blow your engine!! I was planning on taking a smaller sets of injectors with me to the rollers. If we struggled with the 440cc injectors just throw the 220cc’s in there.

When I said to stevegrabba about changing the injectors for smaller ones, this was off the back of someone else’s issues they had with serious over fueling and just trying to get it to run. His engine spec is identical to the one I’m building and so he reduced his down in size. 440 is far too big so fit the 220s and see if that makes any difference.

[Mini_Martin]

I measured between the 2 end exhaust ports (ignoring the middle port) on the billet head. From the inside edge closest to the middle, to, inside edge and got 280mm.

And when measuring from the same 2 ports on the exhaust manifold I got 274mm.

Sonikk I would be really interested to know if we have the same measurements.

I am asking around at the moment to see if there is a fix for this problem.

Sorry never got round to checking this out, some things got in the way this year if I get a chance I will try and have a look.

[Mini_Martin]

No worries mate it took a little fettling but I get there in the end

[Mini_Martin]

Did you get the car back on the rollers?
What was the outcome, did it idle better?
And did the smaller injectors affected peek power?

I only ask as my elf had it’s first start up the other week and is really lumpy above ideal (is underivable). I only have the bace map in and know nothing about tuning... well the only thing I know is don’t blow your engine!! I was planning on taking a smaller sets of injectors with me to the rollers. If we struggled with the 440cc injectors just throw the 220cc’s in there.

When I said to stevegrabba about changing the injectors for smaller ones, this was off the back of someone else’s issues they had with serious over fueling and just trying to get it to run. His engine spec is identical to the one I’m building and so he reduced his down in size. 440 is far too big so fit the 220s and see if that makes any difference.

That settles it I’m gonna get myself some 220cc injectors thanks guys

[Mini_Martin]

 A4616026-F9F4-47D7-96EE-3B4763B203A2.jpeg   125.85K   20 downloads

[Mini_Martin]

I got hold of these 220cc injectors. They are a straight fit to the head and fuel rail, with the EV6 plug on them. Happy Days
Part code 0280 155 844
I haven’t started them up yet. When I do I’ll let you guys know the outcome if they work or not.

[IronmanG]

Good job. I might need some of those

[Northernpower]

Just a few thoughts on injectors and my experience with the SC heads.

 

The injector pulse width is in three phases, the opening phase, the fully open phase and the closing phase. Only the fully open phase can give a truly accurate volume of fuel for a given time. The other two phases vary. When the injector is opening up or closing down it is not consistent in the time it takes to go from fully open to fully closed and vice versa, consequently, this leads to a variation in the fuel delivery during these two phases. Don’t forget, this is all happening in 2.5ms to 3.5ms at 51 times a second at 6,000 revs therefore, it’s imperative to reduce variables. With a large injector these two phases of the pulse can be greater than the fully open phase.

 

With the above in mind it follows that the longer the injector is in the fully open mode (as a percentage of the full pulse length) in any given pulse, the more accurate the delivery of fuel over the whole length of the injector pulse will be. Normally SC supply the 440cc; this is part of their one size fits all policy but unless you’re building a very large capacity screamer that’s constantly revving between say 6,000 to 8,500, they’re way too big. What we found when we changed the injectors down to the 330cc was the percentage (as a ratio of the whole pulse) the injector was in the fully open position doubled in time from the 440cc and given the injector is smaller, the fuel delivery in the other two phases is also less due to the opening and closing timing being the same.

 

On the last engine we built, at 7,750 revs under full load at 1342cc running normally aspirated, the 330cc injectors were delivering just a shade under 71% of their capacity (this is well below the 90% maximum capacity you would not want to exceed) and it delivered 108bhp and 83lbs of torque at the wheels. I don’t know whether I could tell if it ran smoother but I do know the emissions were less and more importantly much more consistent and the fuel consumption improved enough to be measurable as well. We were running it with the wide band lambda with a maximum variation of +/- 7% installed just after the Y piece.

 

The final variable is the fuel delivery. It’s important the pump has a much greater pressure than is needed so when it’s reduced by the regulator there in plenty in reserve to keep the pressure consistent when there is a sudden demand through rapid acceleration. If there isn’t then the volume of fuel delivered through the injector will reduce due to the injector being time-based opening not volume-based opening. This will be helped by very good quality none expanding fuel hose of at least 8mm diameter.

 

I know the above is more important on the race engines we built but it’s extremely good practice if you’re building a high quality road car from scratch as you are.

 

You may want to amuse yourself with this link to an injector size calculator. You'll see for your capacity you'll not need and anything greater the 220cc. 

 

https://witchhunter....jectorcalc1.php

Edited by Northernpower, 27 September 2020 - 07:01 PM.

[IronmanG]

That's very useful thankyou. What kind of pressure pump are we talking about. 50 psi?
Also I cant get the calculator to work?

Edited by IronmanG, 27 September 2020 - 05:14 PM.