I have a MPI system that I am using with a MS-1 on a 383 SBC. Right now I have it set to alternating and 2 squirts per cycle. Is there an advantage (power,economy or fuel atomization) to going to 4 squirts or will this just make the injectors work harder? I am using 29 pph injectors.
Thanks for your input,
Wayne
Number of Squirts
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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Philip Lochner
- Helpful Squirter
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Re: Number of Squirts
I have found great benefits in using more squirts including more torque at lower rpms (not massive increases but enough so that no doubt existed over the improvement), and better throttle response. This was MOST noticeable on my V12 project where the engine is not very torquey at lower rpms.
However, bear in mind that the more frequently you inject, the shorter the PW per injection becomes, the greater the DIFFERENCES in the amount of fuel being squirted per cylinder (due to the differences in opening time between injectors), the greater the differences in AFR between cylinders (even though your WBO may tell you a good figure, keep in mind that is an average), the more rough the engine may become.
When using too many squirts, You may even find (as I have) that it becomes difficult to run the engine in those areas where small PWs are required such as at idle (when hot, no other aux loads) and very light throttle (< 40 kPa) , some cyls may not even get any fuel when trying to get it lean which will result in a very rough engine.
Also bear in mind that your duty cycle will increase as more time is then spent just in getting the injectors open with each squirt.
2/Alt is (as per manual) a good start, but IMHO it is worthwhile to experiment with more squirts. A stable idle at a sensible AFR, with engine hot(CLT), on a hot day (IAT) with minimal engine loads, is a good first indication if the number of squirts you are using will work for you. Keep an eye on duty cycle at WOT though.
However, bear in mind that the more frequently you inject, the shorter the PW per injection becomes, the greater the DIFFERENCES in the amount of fuel being squirted per cylinder (due to the differences in opening time between injectors), the greater the differences in AFR between cylinders (even though your WBO may tell you a good figure, keep in mind that is an average), the more rough the engine may become.
When using too many squirts, You may even find (as I have) that it becomes difficult to run the engine in those areas where small PWs are required such as at idle (when hot, no other aux loads) and very light throttle (< 40 kPa) , some cyls may not even get any fuel when trying to get it lean which will result in a very rough engine.
Also bear in mind that your duty cycle will increase as more time is then spent just in getting the injectors open with each squirt.
2/Alt is (as per manual) a good start, but IMHO it is worthwhile to experiment with more squirts. A stable idle at a sensible AFR, with engine hot(CLT), on a hot day (IAT) with minimal engine loads, is a good first indication if the number of squirts you are using will work for you. Keep an eye on duty cycle at WOT though.
Last edited by Philip Lochner on Fri Sep 05, 2008 9:11 am, edited 1 time in total.
Best regards
Philip
'74 Jensen Interceptor Mk3 (MS-2 EFI, GPIO + GM 4L60e)
'80 Jaguar XJS 5.3L V12* (MS-2 EFI + dual EDIS-6)
and about 10 others.
Philip
'74 Jensen Interceptor Mk3 (MS-2 EFI, GPIO + GM 4L60e)
'80 Jaguar XJS 5.3L V12* (MS-2 EFI + dual EDIS-6)
and about 10 others.
Re: Number of Squirts
Thanks, I will experiment a little and see if it works any better!