Inliners International Forums General Discussion Blown and Injected Siamese Sequential Port Fuel Injection

All, I think people may find this interesting. I am interested in fuel injecting a Packard straight 8 engine, which has Siamese intake ports as many old engines do. The conventional wisdom is that these type of engines can't get sequential port fuel injection, due to the 2nd cylinder robbing fuel from the 1st cylinder, as discussed many times here. I was doing research on this issue. I have found that a group interested in the British Classic Mini from the 60's that was produced there for many decades, actually up to the year 2000 had a 5 port, 4 cylinder engine (Austin A-series) figured out how to make sequential port fuel injection work on a Siamese port engine.

Basically what they are doing is programming an EFI system to think the engine is twice the displacement it actually is and only using the injectors for the 1st cylinder of each Siamese port pair. The injectors are timed to middle versus start or end of spray time, so that the middle of the injector spray is when the 1st cylinder's intake valve closes of the pair.

It takes more time to get tuned, since the injector timing needs to be precise so half of the fuel load goes in each cylinder. A wideband O2 in each cylinder of 1 Siamese port cylinder pair is required to tune the engine. For a 4 or 8 cylinder engine injectors need to be sized for a duty cycle of only 20-25%. So the 1st cylinder doesn't go lean. For you 6 cylinder guys, the degree of separation on the Siamese port is greater so 27-33% duty cycle sized injectors will work for you.

A Megasquirt 3/Extra will do this, but it only supports 2 additional staged injectors in a wet manifold setup, which you may need based on your HP goals. If you have a 4 cylinder engine you can use a Megasquirt 2/Extra with the special Siamese Code, which allows for staged sequential port fuel injection. So for the 6 cylinder guys you could run two efi setups, 1 for the outer 4 cylinders and 1 for the inner 2 cylinders if you have to have staged sequential injection.

I am not running yet so I can't give you real world info on this. I just thought people would want to know. The turbominis.co.uk forum has good information and helpful people if you are wanting to pursue this.
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=612576

Best Regards,
John R.

I think you're on the right path using the middle of the valve cycle for the injection point. Alternatively set the engine as half the number of cylinders and wire the injectors up as pairs. As mentioned, the MS3/3x does this, using the injector timing table timed to the middle of the valve event with a low duty cycle. The lower the HP production of the engine the cheaper it is to get injectors large enough to fit the duty cycle window. Its still a compromise, but it would be pretty close if the cam doesn't have a ton of overlap. I'd be curious to know what the high end of HP production is for Packard straight 8 is?

700HP, 25% duty cycle can use commonly found 2000cc injectors ($$$ though).
300HP, 25% duty cycle can get away with a much cheaper 750cc or 800cc injector.

https://www.witchhunter.com/injectorcalc1.php

Although this is over my head it is interesting. I very much like the idea of applying modern tech to these old engines. Please keep us up on your progress and post some pictures as you go. Been a long time since we've had a Packard here. We have several Packard guys in or local chapter.

I hope the info is useful to people.

The Packard engine is a 359 cid engine making 212 gross HP at 4,000 rpm stock (187 net HP is more comparable to now). I am working on a Packard that will look stock from the outside, just a street car so I am not trying to set a HP record. My plan is to use 4 ea. 1,400cc injectors, which should give me about 400 HP worth of fueling at 22-23% duty cycle, 1500cc and up start getting really expensive. I have 2ea Borg Warner K03 twin scroll turbos from 2007-10 Mini Cooper S which can be separated from the exhaust manifold unlike the newer twin scroll K03's used on the 2.0 and 3.5 Ecoboost engines as well as VW. The 2 turbos seem to provide enough air for 375 HP in my application, along with quick spool. I have the 4 individual throttle bodies off a 2002 Suzuki GSX-R 1000 motorcycle, that I plan to use. Scrounging the junk yards and eBay is my plan. I unfortunately am not quick at getting stuff done so this is going to be a long term project.

Best Regards,
John R.

I'm a big fan of scavenging and making it work!

I am not familiar with the term "1,400 cc injectors" Would you please explain it? I am used to terminology like "19 lb/hr" What is the correlation?

So when it is cycling at 23% to make 400 hp does that mean at 40 hp output it will only be cycling at 2.3%? and at 10 hp (idle) will it be at 0.6% duty cycle? I know I'm ignoring motoring friction for the sake of discussion.

I ask this because one big drawback to larger injectors is the inability of the injector to control fuel at idle due to its non-linearity of fuel delivery at small pulse widths.

Rough conversion (assumes fuel pressure is constant, usually 43.5 psi):
lbs./hour = cc per minute × .0952
1,400cc = 133 lbs./hr.
cc per minute = lbs/ per hour × 10.5
19 lbs./hour = 200cc

Yes, that's for peak power, the BSFC determining the duty cycle (80% suggested max) will vary from .50 for NA (probably close to the usual 12.5-13:1 A/F) to .65 for turbo (9.6-10:1 A/F, extra fuel for cooling and knock suppression).
The problem:
1. too small = lean-out and destruction
2. above 85% sustained the injector will fail
3. too large, the injectors will drool and not respond linear to low speed signals, idle quality suffers.

Yes idle can be an issue, but I have heard from the other group that they had gotten a 61 cubic inch engine to idle well on 1000cc/min low impedance injectors and 875cc high impedance injectors. Scaling up the engine size, the 4 ea. 1,400cc injectors are proportionally smaller in my application (359 cid) than the 2 ea. 875cc injectors in the 61 cubic inch engine. I would think I am ok. But I guess I will find out.

John R.

My 2JZ 183" turbo engine (perhaps 20 psi, .60 BSFC?) has 6 X 550cc injectors for about 520 hp.
If the fuel pressure is lower than the usual 43.5 (common value for stock pumps), that reduces delivery rate significantly.
Rate change:
(New psi / old psi)^.5
Going down from the rated 43.5 psi to (example only) 30 psi:
30 / 43.5 = .69, ^.5 = 83%
That would take your 1,400cc to 1,163cc equivalent with std. pressure.
Seems harmless to try it out, you're not going to cook anything!

Thanks. Guess I need to find an adjustable rising rate fuel pressure regulator. A normal 1 to 1 ratio would be 33 psi off boost and 43 psi at 10 psi boost. Or would a 1.5 or 2 to 1 rise be better, but havent seen those available?
John R.