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McGee machanical injection
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Mr Cool
900RPM



Joined: 27 Sep 2020
Posts: 907
Location: Bacchus Marsh, Vic

Posted: Mon Jun 28, 2021 2:56 pm    Post subject:

SRVLIVES wrote:
I hate arriving late and missing the joke...

Spell it out for him will ya. You need the book with Frank "Choco" Munday's name on it as the author, not that other one. Choco's book is absobloobylutely brilliant
As for the McGee red motor injection, its only 3 trumpets with constant flow injectors (It was about 15 years ago we played with it), and from memory it was fairly tight in the EH too. You may need to re-think this one for EFI or it will lean out in half the cylinders. TBI injectors rather than PFI maybe?
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SRVLIVES
200rpm



Joined: 30 May 2021
Posts: 232
Location: Toongabbie, Sydney

Posted: Mon Jun 28, 2021 5:11 pm    Post subject:

Quote:
Spell it out for him will ya. You need the book with Frank "Choco" Munday's name on it as the author, not that other one.


Well, I did ask him the question now didn't I! An exact link to save me searching around would sure be nice... but alas, I have found it and will order tomorrow.
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choco
800RPM



Joined: 11 Jun 2021
Posts: 805
Location: Queanbeyan, NSW (on the ACT border)

Posted: Tue Jun 29, 2021 7:41 am    Post subject:

[quote="Mr Cool"]
SRVLIVES wrote:
As for the McGee red motor injection, its only 3 trumpets with constant flow injectors (It was about 15 years ago we played with it), and from memory it was fairly tight in the EH too. You may need to re-think this one for EFI or it will lean out in half the cylinders. TBI injectors rather than PFI maybe?


Just run the formula for HP vs Injector Size to determine flow rate. If, say, you are looking at 300HP, 30Lb/Hr injectors would do (for a 6). Depending on what type of computer and injector driver you are running will determine the injector type. Frinstance, I would recommend Kalmaker, so run a high impedance injector, something like the yellow Magna injectors (30lb/hr) or whatever - there's a plethora of factory injectors around.
You are quite right, those trumpets suck a lot of air, and a lumpy cam will make any vacuum signal almost non existant. So either run the system as Alpha-N (TPS Mode) or only have the MAP sensor come in when there's vacuum. As long as the injectors can supply the volume of fuel reuired at WOT, it won't lean out. Most stack injector conversions that I know about run without a MAP, just using the Throttle Position Sensor to determine engine load. A heated O2 sensor is also required.
Here's a thought - NOS now make fogger type injectors - these are big injectors with an extra tit for the nitrous. The computer senses WOT, pulls the nitrous on and bumps up the base injector flow rate at the same time. Heaps safer than the old cheater systems and much more useable, too!
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Frank Choco Munday, Technical Author
Hot Rod Handbooks
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Carburettors SUCK!
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bcal
700RPM



Joined: 04 Feb 2021
Posts: 722
Location: The Shire, Sydney

Posted: Tue Jun 29, 2021 6:01 pm    Post subject:

My megasquirt has no probs controlling in closed loop with manifold vacuums of between just 85 and 95kpa Absolute (ie -15 to -5).
Main problem you can get with individual TBs is that the fluctuations in the MAP signal requires it to be heavily dampened with a restrictor (mig tip or carby jet). This slows the MAP response somewhat on hard accel and can cause leaning out. There is a code mod tho that switches to TPS control (alpha N) during acceleration.
Fortunately I don't need to use it.

If, as MC suggests there are just 3 trumpets then you are only using 3 TBs on siamesed ports and so the MAP fluctuations may not be too great.

Another source if 30lb injectors is Toyota 7MGEs in Cressedas and Supras. You have to watch tho coz some are low impedance and should be avoided. I have a set in my car and they're Nippon Denso with green tops. Good enough for up to 200hp in a 2L so should be plenty for a hotted up Holden six.
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Brett.
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Mr Cool
900RPM



Joined: 27 Sep 2020
Posts: 907
Location: Bacchus Marsh, Vic

Posted: Wed Jun 30, 2021 4:34 pm    Post subject:

bcal wrote:
If, as MC suggests there are just 3 trumpets then you are only using 3 TBs on siamesed ports and so the MAP fluctuations may not be too great.

Yep, only 3 trumpets, so would the ECU need to pulse twice per firing of cylinder no 1 (once per engine revolution)? This would probably work best as the ECU would give you a fuel injector pulse for the first three cylinders (1, 5 and 3), then another for the other three (2, 6 and 4) which will draw from each of the three TBs and then from the same again. That way the lean-out problem would be eliminated. Just a thought. If I'm wrong, tell me.
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bcal
700RPM



Joined: 04 Feb 2021
Posts: 722
Location: The Shire, Sydney

Posted: Wed Jun 30, 2021 5:24 pm    Post subject:

Mr Cool wrote:
If I'm wrong, tell me.

Ok then, I think you're wrong
Both the GM808 and MS are batch ECUs not sequential, so you get an injection on all ports per ignition event.
You could use a sequential ECU but the costs and added complication wouldn't make it worthwhile.
With the MS you can set it for one or any number of squirts per event and you can set it alternate (ping pong) batches of injectors but there are only 2 outputs. The ping pong feature is more for fuel pulsation issues rather than engine management.
Mine is set for 1 squirt per event similtaneous and runs fine.
Choco would be able to comment on the GM system.

With the Holden I see an issue with the 3 sets of siamese ports (Pity it's not the later 12 port) because you would have to decide whether to install one injector per cylinder just near the cylinder head or 1 larger injector
further back in each manifold runner. I reckon the latter may be the most practicle.
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Mr Cool
900RPM



Joined: 27 Sep 2020
Posts: 907
Location: Bacchus Marsh, Vic

Posted: Wed Jun 30, 2021 5:42 pm    Post subject:

bcal wrote:
With the Holden I see an issue with the 3 sets of siamese ports (Pity it's not the later 12 port) because you would have to decide whether to install one injector per cylinder just near the cylinder head or 1 larger injector
further back in each manifold runner. I reckon the latter may be the most practicle.

This is where the problem lies.
If using sequential injection you'll need 6 injectors.
If using single batch injection (as you suggst) the latter 3 cylinders will be sucking in air only.
If using the MS, by setting it for two squirts per event you'd be fine, so long as the 2 squirts occur at exactly the same time apart ie- exactly half way through the firing sequence, to ensure the latter 3 cylinders dont run lean.
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SRVLIVES
200rpm



Joined: 30 May 2021
Posts: 232
Location: Toongabbie, Sydney

Posted: Wed Jun 30, 2021 5:47 pm    Post subject:

(If I be very quiet they'll come up with the answer and I won't look so foolish )
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bcal
700RPM



Joined: 04 Feb 2021
Posts: 722
Location: The Shire, Sydney

Posted: Wed Jun 30, 2021 6:48 pm    Post subject:

Mr Cool wrote:
If using single batch injection (as you suggst) the latter 3 cylinders will be sucking in air only.

Not really. At 1 squirt per event you get 2 per cycle so there should be enough fuel available when the valve opens.
Mr Cool wrote:
If using the MS, by setting it for two squirts per event you'd be fine, so long as the 2 squirts occur at exactly the same time apart ie- exactly half way through the firing sequence, to ensure the latter 3 cylinders dont run lean.

With the MS set at 2 squirts the duty cycle halves for that event so each squirt should occur 1/4 way thru the cycle at a given cycle speed.
I see this working more like 3 throttle body setups on one engine and I would imagine that it would work best at 2 or maybe more squirts per event. That's why I invisage the injector being further back up the runner.
But I must admit I'm getting out of my depth here.
The good thing about MS is that it lets you play around with all these settings yourself and is very easy to understand even for a novice like me.
I played around with all sorts of settings like alternating and multiple squirts until I settled on what worked best.


Quote:
(If I be very quiet they'll come up with the answer and I won't look so foolish )

Is it wiser to ask a foolish question than to make a foolish mistake

Ask questions at the MS board, there's plenty of smart people who lurk there. If I see your post I'll help push things along a bit for you.
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Brett.
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choco
800RPM



Joined: 11 Jun 2021
Posts: 805
Location: Queanbeyan, NSW (on the ACT border)

Posted: Tue Jul 06, 2020 10:54 am    Post subject:

With the batch injection of MS and the GM Delco, the fuel squirts at a closed intake valve every revolution. It has been argued that this is a better mode of injection than sequential for high performance applications, and it is documented that sequential injection was developed more for anti-smog than performance. What Brett said was true, though - sequential injection is far more sophisticated and, therefore, more expensive than a batch or bank system.
I have seen a couple of 265 Hemis running EFI. Check the Kalmaker forum (http://kalmaker.hotrodhandbooks.com.au/index.php), but one thing that was clear is that these in line sixes don't mind having the injectors a little further up the runners, not necessarily pointing directly at the back of the intake valve. Which means that the McGee setup will work just fine if you replace the constant flow injectors with EFI injectors. You can then run a remote IAC. For an inexpensive computer, go the MS or get a Kalmaker tuner to tune your engine and burn you a chip for a Delco computer. I won't enter into a debate with Brett about the differences, because I have used both and they both work great. For all out racing with data logging, MOTEC is the answer.
_________________
<><><><><><><><><><><><><><><>
Frank Choco Munday, Technical Author
Hot Rod Handbooks
Phone: 0412 883 235 or (02) 6255 9810
Carburettors SUCK!
<><><><><><><><><><><><><><><>
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