AFR with procharged setup
 

hoping to fine tune boat this spring...if want to call it that..M3 procharger on a 500HP, what AFR's would be ideal @ cruise & WOT ? Running 6psi ,@ 5600 thanks Rob

you could go 305's but we did the 335cnc's first then used the heads when we upgraded to 540's.so far we got a 38 formula w/ arnesons to 110mph in alittle under a mile from a 30mph start.1 of my videos is on Arneson's web site.:D

I think he meant AFR's not AFR's, lol

Thinking he meant air fuel ratio
Mid 12's to 13 cruise, if you plan on running wot for extended periods of time high 10's, if short bursts 11.2-11.6

i think with the m3 and 6 lbs boost you can get away with a leaner afr than with a roots deal.it also depends on the type of boat and how long the stick will be pinned.

It would be nice to compare egts and see what it likes

yes air fuel ratio...just hoping can get the 02 to live in these lightnings, killed 3 in the last couple of years, put a bung in a tube this time, know it's not ideal, but normal location will not work...

sorry about the confusion(something to ponder later on :D),,cruise I wouldn't go more than 12.8,,wot shoot for 11-11.3.does your procharger have an oil feed and return?friends set up gets the air pretty warm before the biggest intercooler they have,although 6lbs isn't to much.we run 8-9lbs.

No, its a SC(self contained unit), also don't do any real long WOT runs, 25' checkmate, things get interesting !

I recently learned of a M3 procharged intercooled setup that runs 7psi, and has the same air intake temps at wot, as a roots blown 10-71 WITHOUT an intercooler running similar boost . (130-140*)

I think we've all been led to believe roots blowers make tremendous heat and centrifugals simply blow icy cold air out of them.

If its a blow thru carb setup, I'd be very careful with leaning the afrs too much. The fuel distribution sucks on those setups. While you maybe will see 11.8 Afr average from the bank of the 4 cylinders, you very well can have a cylinder in the 12's ....port injection with a good intercooler, high 11's no problem at wot. .

My carb box setups had dams welded in the inlet due to the signal reduction on the Venturi. It would lean down a couple cylinders. Changing the air flow angle alleviated the problem. This was in a HP500/ M3sc with an inner cooler. They would run well but if you got into the throttle and stayed in for more than just a bit, the EGTs would go they the roof. I went back to NA.

joe,while i understand what you are saying,a m3 on a 502 really does not get spun very fast to make 6 lbs boost.this is why in my opinion it can be run a little leaner.and we now know it is in a light small boat so i think 11.5-11.7 he will be fine.i am soon going to be doing a 565 with an m3 making 6 lbs boost and i am a little concerned about intake air temp because that m3 is being spun at the max rpm to produce 6 lbs.i am going to install a air temp gauge in the manifold to assist tuning on dyno day.this engine will find it,s home in a 26 ft cat that will only see wot for 45 seconds max.you can be sure this one will not see lean afr,s.low 10s at wot.

Mike you wont be anywhere near max blower rpm at 6#s. Also, overly rich afr is usually a crutch for insufficient octane, and really isn't the best plan for an endurance application. The unburnt residuals can compound and actually promote detonation, there's also the risk of fuel getting past the top ring and combusting between the ring lands. As you know though, they're all just numbers. Give it what it wants and it'll be happy, and live a long time.

M1 is limited about 7lbs, I think the M3 will do 12lbs or so....

also knowing that 02 now only in 1 tube vs the collector have to roll that into the deal as well.

Cool beans. I remember years back here there was a company making some intercoolers for procharged setups, that seemed to really help with bringing the air intake temps down. Not sure if they are still around. From what I been hearing lately talking to some procharger guys, ATI's intercoolers arent all that great.



http://www.offshoreonly.com/forums/g...percooler.html

we are using a blow thru demon with the boost referenced throttle shafts with a hat, while back ran a prosystems blow thru in the box..worked ok, just a pain to deal with, then did EFI but could not stop the RFI interfence from messing with tha ECM. We are not running the procharger intercooler, have a larger one mounted on the floor. Back when we had the EFI on we were seeing inlet temps less 100.

Cool. Which intercooler are you running ?

Scott had issues with his, almost cost him an engine, he is using another persons coolers now, not sure who made them , I will try to ask him..

Which cylinder are you going to measure ? Just curious.

#5, no idea who's intercooler, was on the boat when I got it, floor mounted, have not seen one that looks like it