AFR recomended for crusing in boat?

AFR BOAT vs CAR?

Introduction:

I`m new to programming Afr. I do know a lot for engine building, Naturally aspired, Carburators etc. But its the first time I myself is going from Holly carburator to Fitech throttle body system in my boat.

Hardware setup: Chevy petrol 632 Cubic inch ( 10,4L ) , engine-V8. Max rpm 5500. Naturally aspired. And it`s used a lot of money into this machine in balance and

total build up,including increased toleranses for piston / sylinder bore etc etc. Machine vise adapted for marine use.

AFR:

The boat is heavy. The engine is as mentioned naturally aspired, producing 700-750 hp. Top speed like 70 mph.

I will travel long distances also with this boat in cruise speed ( 35- 50mph ). So it is important to find the cheapest / leanest Afr I safely can

drive the engine within the rpm range 3000 - 4500. The output power will probably be like 350- 550Hp in «constantly use»!!! ( Compared to car, do this mean constantly driving uphill with a full trialer )

So yes- . It is extremely hard use in this cruising Rpm. Of course I also is interessed in maximum power :) . This will be in the area 5000-5500 Rpm, but there its not so neccesary to run lean. There I can only think "power" and normal cooling.

Experience- recomondations:

* Do anyone have experience in this matter- Cruising Afr in boat. Is there any pre suggestions comparing to a car.? Do it need to be so or so much richer... Or just follow normal Afr setup or???

Injection setup:

I will have the Fitechs map / Afr sensors. The Afr system can be adjusted as you see attached in the Fitech pictures. And it is the thottle body system.

Privatly I will install exhasust temp. Both Exhaust sensors ( temp and Afr ) will be in the area where all 4 exhaust on one side has got together to one exhaustpipe, like 1,25 feet ( 40 cm) after exhaust outlet. Inside exhaust diameter 3,5inch.

Excited for you answers guys. : )

Best regards. Nils

Personally, because it's so difficult to get best lean torque, I'd be going for around 14.7 (stoich') and 15.5:1, and as much timing as the engine will take while keeping clear of detonation.

As an aside, there's a, IIRC, shop teacher building up something very similar, who posted recently on one of the "engine builder's" channels, was that possibly you? I was thinking off-road/rock crawler, but might have been wrong.

Thx Gord. Super answer : ) Do you mean 14,7 wot and 15,5:1 with cruising?

Double posting no. This is my first post here ever. But if you have a link to the post you mention it be good to look there also at the case and answers.

I have earlier had a crash in this engine. So I want to be safe, using your guys eqperience as help : )

If I go as lean as you suggest. Will I read this as increased exhause temperatur if I start richer and lean up against your suggsetions? Meaning: Can this also be a guide for me that I see a quicker change in increased temperatur as i tune against a "to lean level"?

As told. Im new inte this kind of tuning game. So sorry for asking a lot, hehe. : )

I'd be looking around 13-13.5 under full throttle, around 14.7 for medium load/around half throttle, around 15.5 for light throttle. using a curve with smooth transitions.

Yes, it is similar to towing up a hill, on part throttle.

The post I was referring to was in the comments of a Youtuber's channel, rather than here.

THX a lot again Gord. : ).

BR Nils

Personally I'd be a little conservative with this application. Boats are VERY different to cars in so much as you can be at WOT for minutes on end in a boat. The closest automotive application is land speed racing. Due to this potential for sustained high load our calibration becomes more along the lines of component protection rather than maximising power or economy (within reason). The other big difference with your application is that 'cruise' in a boat is going to require significantly more power than you'd use on the road hence the engine load is also higher. It sounds like you're on top of this as you suggest the engine may be producing 350-550 hp in this operating regime and 700-750 under WOT.

I'd be inclined to aim for around 12.5-13.0:1 under WOT and probably in the region of 13.5-14.0 under cruise BUT that is simply a starting point. For a marine application I'd be installing EGT (as you are doing) and then seeing what the EGT stabilises at in each operating regime. The numbers I've suggested I would consider to be quite conservative for an N/A engine so you can most likely lean them slightly from there once you see what the EGT is looking like. Tread carefully though as the additional fuel cost of richening the target AFR 0.2-0.3 is infinitely cheaper than a rebuild.

Hi Andre.

Super thx for your answer. I see you have read both my setup, and consider my use! This realy gives me trust :)

As you say: A boat is very different to cars. One thing is WOT constant for minutes, but also cruising with the thottle far more pushed in at medium rpm`s for hours.

This said. I have 2, for me, complex questions. I am «new» in this Afr / tuning game for setting it up myselves, so sorry if I see things wrong or ask stupid, hehe.

My 2 qestions are:

1 What sign (changes) to look for at Cruise speed, when I adjust AFR lean and then ignition. The overall thing is still to have a safe setup!

2 What sign (changes) to look for at WOT, when I adjust for Maximum power, and then ignition. The overall thing is also here to have a safe setup!

Before i explain my questions a bit more, I quicly repeat my setup and add one thing, knock sensor, that might help me?

Chevy 632, 10,4 Liter (632 cubic inch)

Max rpm 5500, the camshaft gives realy much power in medium Rpm ( Marine setup )

Fitech throttle body that can be adjusted at idle, 1100, 3000 and 6000 rpm at different Kpa`s (Egt) (pictures attached in earlier text)

Exhaust temp sensors

Exhaust and Egt sensor located approxemataly 1,5feet after outlet from expansion chamber. (where the 4 exhaust pipes has come into one 4inch exhaust pipe (3,5» inside diameter)

AND

I Also have bought a Knock sensor system. The sensor is installed in senter at the intake manifoil, at the horisontale plate under the throttle body. (On the up side of this plate, not on the bottom side over the camshaft- oily space)

But, I have not read any tests about this equipment if it is something I can trust…..

https://www.viatrack.ca/ The sensor though, is standard reliable equipment.

This is a standalone system. Showing a red lamp when going at knock (see attached picture), and it has an adjust screw.

I have 2pc 4inch loud exhausts, (straight through). So this is what I thought is the best way to SEE the knock straight - «right in my face» if it happens offshore …. :)

With this above in mind, then my 2 questions above explained a bit more:

1

Cruising 3000-3500 Rpm

What procedure is the best (a safe way) to start? Leaning up Afr to knock for a realy short time? Do I chrash the engine? Same with ignintion after- adjust to knock and go back from there?

Or not use the knock at this RPM`s at all but first adjust AFR and then Ignition? ( Only test the knock system at idle? ) If I do it this way, leaning up the Afr at ruise Rpm. - Tthen: What sign tells me when I go from «helthy to «to lean»» (I`m thinking- changes can be: Exhaust temp increase?, Or - go for reading spark plugs?? (but his take much more time? ……… or? Is it only an Audio knock sound like Knockblock G4+ that realy gives a safety… ?)

Sumup: What is safe and correct way to proceed in this process?

2

And exactly the same question at WOT 5000-5500 Rpm. With max SAFETY and POWER as the first prioriteys.

Maybe do Wot before Cruise?

Realy hope for you answer Andre And yes. I bear in mind your sentence: Due to this potential for sustained high load our calibration becomes more along the lines of component protection rather than maximising power or economy : )