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-   -   AFR with procharged setup (https://www.offshoreonly.com/forums/general-q/325583-afr-procharged-setup.html)

endeavor1 04-26-2015 10:50 PM


Originally Posted by MILD THUNDER (Post 4297206)
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.

mike tkach 04-27-2015 12:00 AM


Originally Posted by MILD THUNDER (Post 4297206)
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. .

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.

HaxbySpeed 04-27-2015 01:18 AM


Originally Posted by mike tkach (Post 4297219)
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.

Full Force 04-27-2015 04:48 AM

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

ezstriper 04-27-2015 06:02 AM

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

MILD THUNDER 04-27-2015 06:07 AM


Originally Posted by mike tkach (Post 4297219)
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.

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

ezstriper 04-27-2015 12:24 PM

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.

MILD THUNDER 04-27-2015 12:26 PM

Cool. Which intercooler are you running ?

Full Force 04-27-2015 04:49 PM


Originally Posted by MILD THUNDER (Post 4297243)
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

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..

hadleycat 04-27-2015 04:55 PM


Originally Posted by ezstriper (Post 4297242)
also knowing that 02 now only in 1 tube vs the collector have to roll that into the deal as well.

Which cylinder are you going to measure ? Just curious.


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