2000 7.4 MPI fuel pressure question

[E4ODnut]

Re: 2000 7.4 MPI fuel pressure question

Some figures from the table are as follows.....
Ethanol AFR
00.0% 14.68
06.2% 14.32
12.5% 13.97
18.7% 13.61

rounded off 20% ethanol lowers ARF 1%

Ok heres some more...literally

http://www.mastertune.net/faqsMasterTune-HD.html

Q: What is the best AFR for power?
A: Keep in mind that every motor is a bit different and that gas composition can vary substantially. In general, we find the best AFR for WOT power is between 13.0 to13.5:1 AFR. However, these settings can build a lot of heat so it is best to go a bit to the rich side. For street use, using a AFR setting of 13.0 is a good compromise between power and economy. Keep in mind that alcohol fuel blends require a lower AFR for maximum power than straight gasoline. Also, if heat is a problem it will be better to run a lower AFR


"Also, if heat is a problem it will be better to run a lower AFR"....................

Oh,. We're talking about AFRs. I thought we were talking about Mercruiser hardware components.

OK then. If there is a heat problem and we are talking about gasoline as a fuel, then I can see about 12.5:1 as lower, but not 11:1 and 10:1 is completely out of the question.

The table snippet you quote looks logical to me, where did you find that?

If we are talking about E15, then looking at the table, for an equivalent of 13:1 straight gasoline I can see about 12.17. If we have a heat problem, then as low as about 11.76.

This is for E15, not straight gasoline, E10 will tolerate a leaner mix, straight gasoline leaner yet.

I'm just going by the numbers you provided.

 

[Tail_Gunner]

Re: 2000 7.4 MPI fuel pressure question

Keep in mind all of the info and links pertain to automotive with closed loop systems....You will find very little on marine efi...OS sensors and adapters have only been around for a few years now. Try to find a wide band system that will read marine I/O exhaust..

MEfI 4b has that capability to work with os sensors...Honestly were back in the 80's with marine tech. I wish i still had pics of my plugs coming out of a 4.3 tbi with mefi 3...To say dark carmaled was going easy and they ran quite well.

Theres enough info in the above links to get a grasp on how rich it runs...Quite intresting actually and 11 or 12 could be the case... honestly i dont know for sure 10/11 is a WAG

 

[E4ODnut]

Re: 2000 7.4 MPI fuel pressure question

Keep in mind all of the info and links pertain to automotive with closed loop systems....You will find very little on marine efi...OS sensors and adapters have only been around for a few years now. Try to find a wide band system that will read marine I/O exhaust..

No problem. Got it. Done it.

 

[Tail_Gunner]

Re: 2000 7.4 MPI fuel pressure question

No problem. Got it. Done it.

And the answer is......No problem alcohol actually enhances AFR you have no issues...