EGT with Prochargers/Whipples
 

Ok Procharger & Whipple guys.... question??

What is your EGT at 3000 rpm cruise & at WOT?

I am hitting right at 1400 degrees at WOT on one engine & 1300-1350 on the other. Seems awfully "warm" to me!! What are you reading???

With my Procharger, I am about 200° - 300°cooler than I was stock!!!!:eek: I wanted some stock numbers for comparing, so I mounted my dual EGT gauge to my bone stock 1999 502 mag MPI. I was shock to see that at WOT was getting a reading of 1550° - 1600°:eek: :eek: Stock!!!!! after putting on the Procharger I was reading around 1250° at 3500, and just under 1350° at WOT... I then increased the fuel pressure to 40PSI at an idle(it was at 36 psi before) now my temps at WOT droped to just under 1300°... The whole time the EGT probe stayed in the same location..

Now when I bought my 2002 Sunsation, it also had a 502 Mag MPI. I had such good luck with the 1999 engine that I desided to swap engines instead of buying a new procharger and doing the work to this engine. And besides, selling an old boat with a brand new engine is easier....;) But I didn't swap any gauges because they didn't match the new boat. To make a long story short. I put the probes in the new engine so that the gauge on the dash would work with the new engine.... well sure enough, the new engine had 1550°+++ EGT's at WOT!!!!!:eek: Stock!!!

I have over 260 procharged hrs with EGT's around 1300°

I thought that "melt down time" was at 1450*.... so that is not true????? I should not worry about this??? It is two brand new engines, so I want to be sure.......:crazy:

NO!! Melt down is at 1450°..... I was just explaining that I was reading those temps on the 2 different 502's I had. It was just weird because they were 100% stock????

I would go out and take down numbers at a certain rpm. then stop and increase the fuel pressure by 2-3 psi. then go back to the same rpm, and see what the temps are. I did that about 4 times, till it didn't make a difference. Then I went back down a pound or two, and did a WOT plug reading. You are intercooled right????. In this boat I had to go up a few more psi from the 40 psi I was using in the Stingray. I blamed that on the extra load the Sunsation had compared to the Stingray. I am at 43 PSI at an idle.

I am at 46# pressure at idle, intercooled yes, engine temp 105-115*and 3# boost at WOT. Az Speed reworked the ecu's again to add more fuel between 2600-3500 rpm..... it helped but still way up there....

HUM???? Mine is reworked by AZSM as well B.Formula. I went with there 50 lbs injectors, 2 bar map, reprogram ECU. I am at around 43 psi. Are you running the stock 36lbs injectors??? because I know with 3 lbs + boost, those injectors are running at 95%, which is alot for an injector. Thats why I went with AZSM recomendations of 50 lb injectors. I run at 6 lbs of boost...

I would like to do the Mefi 3, 3 bar map sensor & injectors but building this "hot rod" Sonic 31SS, leaves resources a little tight for an over $2000.00 upgrade just for the MEFI 3 & Map Sensors for twins..... with the injectors on top of that!! I just have to be cautious and not bend the throttle too much or especially for too long.!!

I hear you B. Formula. Two motors twice the price.....:eek: I would try more fuel pressure and see what that does to the egt temps.
Good luck my friend
Claude

Another thing to consider is placement of the EGT. From setup to setup you can get varied temps and still be ok. Distance from the exhaust valve is critical. On a before and after test it would be relative, but on setup to setup, becareful to compare apples to apples..

Good luck guys..

Mr Gadgets:
Both sensors are mounted in the same location on both engines. Depth or distance from the valve can or will vary slightly & so will sensor to sensor..... but if you are running within 100* of destruction, your careful!!

I have flown airplanes with EGT's for 36 years. Here is what I know about combustion heat and mixture. Take one state of the engine for this discussion, W,O.T. Apart from detonation, excessive heat will kill your pistons and or your exhaust valves unless you are cooling with fuel. The temperature in your combustion chamber will go up with leaning to a point (happens to be the peak) then the temperature will go down with further leaning but you do not have enough mass flow to take the heat away from the two parts I mentioned (piston & exhaust valve) This latter state is called lean side of peak (bad side to be on). What you want is to be on the rich side of peak where you have Mass Flow (created by a richer mixture) to take the heat out the exhaust. The important fact is, where is the peak not what the temperature is. Here is why. You can't really properly measure the temperature due to thermo losses related to probe positioning and conductivity to surrounding heat sinks (metal). What you can do is to see where the peak is relative to leaning and once you find it then richen by 50deg or 100deg to be safe. The person who was testing with increased pressure and the temp was rising was on the right track as he was on the correct side of the curve. leaning made the temp rise. He might have been too close to peak however so you should keep leaning until the temp drops and then you know that you are on the lean side of peak. Now richen the mixture until you see the temp falling and you are now safe. These gages are not accurate enough to give you an exact temp, but you should not care because all you care about is peak and any Gage in most any location will show peak. The more expensive gages for airplanes only show a star near peak and no numbered gradations except bars on 50deg increments. If all this is too confusing call me @ 530 587 4700 Baronbob

BaronBob

What about max cruise fuel economy. Where should
your EGT's be in relation to peak?

And on supercharged marine motors, many guys run too close to detonation to safely play with trying to find peak EGT since detonation will cause temp spikes that a cheap gauge won't identify properly.

boom

I get 1350 on the # 2 cylinder at the port in the manifold and 1300 on the #7 in the mani at the port. At 3000 rpm the probes run about 1100 deg./1150 deg. The reason its on the 2and 7 ports is because those are the 2 pistons that melted last time. Greg

I see about 1150-1200 at 3500 rpm and 1250-1300 at 5500 rpm.
This is at ~7.5 lbs gauge and ~5 lbs absolute manifold pressure due to altitude (5000 ft).
9.25:1 static compression ratio.
91 octane.
Timing vs absolute manifold pressure is 34 at 0 lbs, 33 at 1 lb, 32 at 2 lbs, 31 at 3 lbs, 30 at 4 lbs and 29 at 5 lbs.
A/F is 13.5:1 at idle and gradually ramps to 10.8:1 at WOT.

The beauty of a FAST ECU and wide band O2 sensor :D

1400 sounds a touch high. Follow Kanook's suggestion and up the fuel pressure on the one motor and see what it does.
Another twist is that I've also heard that too much fuel (and also lack of timing) can also cause excessive temps. :eek:

Dave

This weekend I am going to have to check my EGT probes to see how far they are stuck into the manifolds.
At 3000 rpm there is about 300* difference between the two engines.... everything else is the same on both engines so maybe it is something along those lines. No other way to explain it that I can think of. :confused:

NordicHeat, Why so rich at WOT? How do you like the FAST ecu? What wiring harness did you use? Do you use the knock sensor? I think that it is my next venture.

Marty,
I went with the suggestions of Dustin and a few others. It works out well and I have very little transom soot after WOT runs. I'd rather be a tad on the rich side anyway.
The harness came with the ECU and I use an aftermarket MPI set up.
I'll try and attach a picture...
PM me if you have any questions.
Dave

Blown F. try swapping probes and swapping the wires on the guages, If the 300° swaps along with it. then you know its not the engine. It's either the probe or gauge. Then swap the gauge wires again, if it stayed on the same side, then you know it's the probe.If not, then it's the gauge.:):)
Good luck

Check your timing also.Late(retarded) will cause high egt.ALWAYS pull a plug to see if it agrees with your egt.Guages & egt probes are just for reference,plugs don't lie.Bob