Air fuel ratio for direct drive

Automotive powered airboat discussion.
Keeth1123
Site Supporter - I
Site Supporter - I
Posts: 316
Joined: Fri May 16, 2008 8:54 pm
Location: Polk County
Contact:

Re: Air fuel ratio for direct drive

Postby Keeth1123 » Thu May 09, 2019 5:39 pm

What temp is it getting to. Took a little bit to get the air out of my system. Let it sit for a few with the burp tank cap off. It would burp and need some more fluid. Ran it on the trailer for a bit and topped it off. Topped it off a week later before ride and it was good to go
:old_glory:

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Thu May 09, 2019 6:58 pm

Keeth1123 wrote:What temp is it getting to. Took a little bit to get the air out of my system. Let it sit for a few with the burp tank cap off. It would burp and need some more fluid. Ran it on the trailer for a bit and topped it off. Topped it off a week later before ride and it was good to go

It crept up to 206, then I shut it down. I let it cool for a while then did it again, same result. I changed to a 180* thermostat because the EFI learns above 170* I was told. I was searching around the forum and saw people drilling a hole in the thermostat to help air escape, I didn't do that, didn't know it was necessary. I'm going to let it cool, check the coolant and try again tomorrow. I might pull the thermostat and drill it.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:

Keeth1123
Site Supporter - I
Site Supporter - I
Posts: 316
Joined: Fri May 16, 2008 8:54 pm
Location: Polk County
Contact:

Re: Air fuel ratio for direct drive

Postby Keeth1123 » Thu May 09, 2019 7:08 pm

Hmmmm. I can’t speak for the EFI deal. I want the setup you have but don’t feel like messing with it. My carb setup runs a 165* thermostat with no holes or anything drilled. I added a bottle of a Lucas coolant product with my dex cool coolant. It runs at 170 to 180. Will rise to 200 if you shit down after running dry.

I can’t rmemebee what my DD 350 used to run but I know it was cool. I wanna say like 165. Had a big block size radiator on it though
:old_glory:

Keeth1123
Site Supporter - I
Site Supporter - I
Posts: 316
Joined: Fri May 16, 2008 8:54 pm
Location: Polk County
Contact:

Re: Air fuel ratio for direct drive

Postby Keeth1123 » Thu May 09, 2019 7:14 pm

Hmmmm. I can’t speak for the EFI deal. I want the setup you have but don’t feel like messing with it. My carb setup runs a 165* thermostat with no holes or anything drilled. I added a bottle of a Lucas coolant product with my dex cool coolant. It runs at 170 to 180. Will rise to 200 if you shit down after running dry.

I can’t rmemebee what my DD 350 used to run but I know it was cool. I wanna say like 165. Had a big block size radiator on it though
:old_glory:

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Thu May 09, 2019 7:16 pm

Keeth1123 wrote:Hmmmm. I can’t speak for the EFI deal. I want the setup you have but don’t feel like messing with it. My carb setup runs a 165* thermostat with no holes or anything drilled. I added a bottle of a Lucas coolant product with my dex cool coolant. It runs at 170 to 180. Will rise to 200 if you shit down after running dry.

I can’t rmemebee what my DD 350 used to run but I know it was cool. I wanna say like 165. Had a big block size radiator on it though

99% sure it's air, I'm trying to figure out the best way to purge the air, on my car I had bleed screws.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:

hdsadey
Southern Airboat Member
Posts: 237
Joined: Sun Jul 01, 2012 7:42 pm
Location: venice fl.

Re: Air fuel ratio for direct drive

Postby hdsadey » Thu May 09, 2019 8:35 pm

On my Windsor I drilled a small hole on the side of the stat. It sure helped with the air purge. There is a funnel from Lisle tools that uses an adapter to the radiator cap that will let the system run and bleed off air.

https://www.summitracing.com/parts/lil-24680/overview/

I also run a product called Hypercool which is an additive to help prevent corrosion when using straight water. Water helps transfer heat much better than anti freeze.
02 Predator 12' 0320 Lycoming
92 Big O 13' Ford 408 Windsor DD Dry Runnin MOFO!
99 Donzi 16 Classic 350 Vortec

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Fri May 10, 2019 6:53 am

hdsadey wrote:On my Windsor I drilled a small hole on the side of the stat. It sure helped with the air purge. There is a funnel from Lisle tools that uses an adapter to the radiator cap that will let the system run and bleed off air.

https://www.summitracing.com/parts/lil-24680/overview/

I also run a product called Hypercool which is an additive to help prevent corrosion when using straight water. Water helps transfer heat much better than anti freeze.

I'm going to drill a hole in the stat today. I have one of those radiator funnels. I'm going let it run with the expansion tank open and the funnel in place.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Fri May 10, 2019 3:07 pm

Drilled the hole, it was still creeping up to 230 at idle, decided to give it some rpm and see if I could force the bubbles out. Worked like a charm, idling at 190 degrees and cruising at 186-188. It ran awesome at idle, cruise, and WOT. Picked up 100rpm on the trailer. I know it takes time to learn, but sudden throttle changes would make it stumble and going WOT from a low rpm would make it hesitate for a few seconds. I'm going to let it learn for a while before I change anything, only put 2 hours on it.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:

hdsadey
Southern Airboat Member
Posts: 237
Joined: Sun Jul 01, 2012 7:42 pm
Location: venice fl.

Re: Air fuel ratio for direct drive

Postby hdsadey » Fri May 10, 2019 5:19 pm

Yeah it's hard to resist not stabbing it to see how it reacts. Time is the key!
02 Predator 12' 0320 Lycoming
92 Big O 13' Ford 408 Windsor DD Dry Runnin MOFO!
99 Donzi 16 Classic 350 Vortec

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Fri May 10, 2019 11:17 pm

Oh, and I dropped the timing to 32, it was at 36. Might try to bring it back up and see if it picks up rpm.
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:

User avatar
Slidin Gator
Site Supporter - IV
Site Supporter - IV
Posts: 645
Joined: Sat Feb 03, 2018 11:33 pm
Location: Jupiter Farms, Florida

Re: Air fuel ratio for direct drive

Postby Slidin Gator » Sat May 11, 2019 12:06 am

keys2pines wrote:Oh, and I dropped the timing to 32, it was at 36. Might try to bring it back up and see if it picks up rpm.

My old notes say go back to 36 and try 38. But Hdsadey is right, give it time to settle first before changing anything. Just don't give it too much time, you don't want her to settle on old lady going to church mode.

My experience with automotive EFI systems is about 30 miles of driving is pretty settled. Call it an hour of training. I would force the tune with 5-10 minutes of steady state RPMS (2,000 2,500 2,800) and then go aggressive on the throttle. You don't want to train it to be a Pu66y motor. It's just like training a new puppy, give it a day or two to get used to the smell of the place, then you gotta show em who the boss is real quick so they are forever scared shirtless of you and react when you say do it, no matter how big they grow. They are all stupid animals just looking to please.
I grew up thinking I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540, 72” NGQ. A Bob Stossel original.

User avatar
keys2pines
Southern Airboat Member
Posts: 107
Joined: Thu Jun 28, 2018 10:55 am

Re: Air fuel ratio for direct drive

Postby keys2pines » Sat May 11, 2019 8:57 am

Slidin Gator wrote:My old notes say go back to 36 and try 38. But Hdsadey is right, give it time to settle first before changing anything. Just don't give it too much time, you don't want her to settle on old lady going to church mode.

My experience with automotive EFI systems is about 30 miles of driving is pretty settled. Call it an hour of training. I would force the tune with 5-10 minutes of steady state RPMS (2,000 2,500 2,800) and then go aggressive on the throttle. You don't want to train it to be a Pu66y motor. It's just like training a new puppy, give it a day or two to get used to the smell of the place, then you gotta show em who the boss is real quick so they are forever scared shirtless of you and react when you say do it, no matter how big they grow. They are all stupid animals just looking to please.

That is by far, the best explanation of tuning I've ever read :lol: . This system is supposed to continually learn, but does most of it in the first 200 miles, so probably 5-8 hours of driving. Once I realized that it would stumble on sharp throttle changes, I actually was doing what you said and run it harder. I probably did 5 dead stop WOT runs, did a bunch of letting off then stabbing the gas. I was trying to get it to learn to adjust for that. It was hard to tell what was happening because the AFR would go dead rich 10.0, then shoot to 20, then settle at 12.5 once it got going. I think it was putting too much fuel, then cutting back too much. It's fine though, I'm going to be patient for a few more hours, data log, then start tweaking. According to the fuel burn rate at 27mph, I was getting 3.5mpg. :usa:
12x6'8" Taylor deckover, 383 DD, 72" Sensenich JM
Our keys house for rent, 10% off for SA members https://rentalsfloridakeys.com/view-unit/l/Marathon/MA770/#image-10 :usa:


Return to “Automotive Power Only”

Who is online

Users browsing this forum: BigRed350, Bill.Braski and 7 guests