EGTs how hot?

Nov 26, 2007
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I have learned that there are so many variables. It depends how far your probes are from your pistons, the temperature your sled likes to run at etc.. I suggest that you read the plugs, top of the pistons and get a feel for the engine performance and then monitor your egt temperature. If you decide on a specific temperature and then try to tune to it, you will be replacing a piston and cylinder (that's what I am going to be doing in about an hour). This sounds advice sounds like your defeating the purpose of having egt's, but I have found that they are device to help monitor, not to solely use for tuning. They work fantastic if you find the base line that your engine likes and your are changing elavations, barametric pressure, temperature, etc. frequently. Once you find the base line, you should have it licked. My M8 (kit) runs great around 1200 to 1225 on top end. Mid range I better be around 1150 at max or I have iron to replace. I sure hope this helps. Again, this is my experince and some one else may have a better explanation. Good luck. :)
 
Nov 26, 2007
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Cranbrook B.C.
I know about reading the plugs and mine are looking great but I didn't do any real climbs and later I checked my max reached egts on the gauge and it was 1350 and 1352 . just felt this was a bit hot for my setup. my probes are just past 6 inches from the skirts.
 
Nov 26, 2007
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It sounds like your probes are about the correct distance. If your piston looks good, no problem. On my sled, my probes are six inches as well. When I see those temps, I'm adding fuel as soon as possible. I think if you run those type of temperatures very long, your asking for a seizure. If your base line is at those temps, then that's a different story.
 

AaronBND

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Nov 12, 2005
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I have a UB900 in my M7 and run the hottest at around 6000-7000rpm's which is about 1230-1275. Usually WOT, and below that I am around 1120-1150 on the gauge. Still trying to dial the BD box in though. I'd like to get those mid's down to around 1200 without loading up the engine though. Not sure if it's possible though! Good luck.

Aaron
 

oldcrow

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Dec 13, 2007
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I'm running a basicaly stock 800 Crossfire. Only thing I've done is install carbon fiber reeds and opened the reed stops to 14mm.

In the mid I see 1350-1360F, drop down to 1100-1200 WOT.
Plugs and wash look a bit rich.
 
Nov 26, 2007
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Cranbrook B.C.
I'm running the speedwerx y pipe and pipe, jaws can, v-force reeds and speedwerx intake and 1350f was in my mid and on top I was around 1150, all this and no fuel box. I was at 4000 feet also. looks like my setup is working well then. thanx for the replys.
 

tatorsalad

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Nov 26, 2007
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egt

I have a m-7 with rkt 800 top end and it runs real hot around 6-7 1300-1350 and it seemed to have good looking plugs with the slp twins still a little scard of it
 
Dec 21, 2006
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Would you guys please post how far you are from the piston skirts when you are talking temps. I am running a SLP single on my M8 and SLP installed the weld on mounts for me. I measured them at about 2" from the back of the y-pipe flange. This is my first set of EGT's but I have my sled ripping. I have seen temps at about power valve engagement at about 1225. I have my warning set at 1150. I am going to check the plug wash.
 

DeepInTheTrees

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Nov 26, 2007
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Mine are 2.25" from the y-pipe flange. I believe the further you get away from the cylinder the temps increase. This is just what I have heard, haven't really field tested it, although my brother has the exact same sled (M8T) and his probes are about 2 5/8" and his temps are hotter (could just be because it is a different sled). But he is replacing a piston tomorrow morning, so who knows...
 

frock

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Sep 13, 2005
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Ignore your EGT

When you first start dialing in your sled ignore your EGT. Look at your plugs and more importantly your piston wash. When your sled is dialed in using these things then take a good long WOT run where you are really working the engine and then look at your peak temps on your EGT. These temps are now what you want to aim for when you are tuning your sled. As long as your probes are installed close to manufacturers recommendations you should be fine. There recommendations are basically a guideline and that's all. My brother in law ran a 925 genesis in a polaris chassis that ran at 1400 deg all day and loved it. His probes weren't placed properly and the temps proved it, but he tuned his sled first then used the resultant EGT temps to keep it running there. Hope this helps, M8Sean.:D:beer;
 

JMCX

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Nov 26, 2007
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I've had the same Racepak for about ten years now, just move it from sled to sled. All of them were Doos until the King I have now. I have always aimed for 4" from the piston skirt with the probes.

On the Doos it was very common to hit high 1300's and even 1400's at mid range with stock jetting. I never lost a piston on any of them and never blipped the throttle when I saw those numbers, just kept on riding. Wide open I was happy with 1250 based on plug readings.

My EFI King Cat will run about 1300 cruising on the trail and 1150 is good on the climbs. I cut the heads 10 thou. and squeeked pistons twice at less than 1200deg. Now have to add octane boost.

The advice to look at other indicators first is a good one. Probe placement is everything. A guy I know who had twins with probes at 8" could run 1400 at WOT.
 

JMCX

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Nov 26, 2007
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I talked to Jeremy at Speedwerx about probe placement and he said I should be 6-8 inches from the skirts. and thats what I did 6 inches from the skirt on my M8 .
Didn't that put you into the convergence of the Y? Not going to be any difference side to side there.

4" is what the Doo and Cat race manuals use to recommend for single pipes but that may have changed.
 

Meatman

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just to reiterate what some of these guys were sayin, you have to tune your sled to the EGT gauge first. watch your plugs and piston wash
 
Dec 17, 2007
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Cat Efi Sleds Will Run Mid 1300 Deg At Midrange. If You Try To Add Fuel To Richen Up The Sled Will Develop A Bog Or Rich Spot. If Adding Fuel To Midrange Just Add A Little. Your Main Concern Is Wot. If You Want To Be More Accurate Use A Wideband Air Fuel Ratio Setup. They Can Tune A Sled Dead On.
 
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