First off,I understand that you should tune off the time slip and tune for best performance. That being said what are some ballpark EGT numbers and A/F ratios you guys are seeing in alky injection and running 1/8 mile? Reason I ask is I have both and my builder is comfortable tuning with egt and i’ve always used O2. My set up is 598 conv head deal topped with terminator, ran 4.78 at 146 first time out since rebuild and a few combo changes @ about 2000 lbs.

I found on the gas scale 11.8 to be a good number. Not a big egt tuner either but it's better than nothing.

I prefer tunning by the spark plugs. EGT and O2 can be misleading and not something you can really take from one car to the next. But the plug, it's a witness to the event.

EGTs are only useful once you have found your sweet spot. They can vary from car to car and distance from the valve. 02's are always right if you have them mounted in the tube and not next to the collector. O2's will get you close to perfect on their own, EGTs will rely on you finding your best time slip.

Agree egt's are a reference more than a exact tunning number. Too many variables.Sensor location is big one and if rich and burning fuel out exhaust it will make you think lean when its fat.

My rule has always been plugs and et,then whats egt's.Then if leaning and run quicker adjust target number.

As for temp numbers I have seen 1000 to 1300 work and thats huge span. On our TA cars 1050 was fast 1100 was time to check bearing and 1150 meant break out another piston. Now thats blower and more extreme.

If you are new to injection my suggestions are. Find someone who runs it and does well and see if they will help you get baseline. If thats not possible then a flowed system is about 500 bucks and the best money you will spend. Bonus is you can always call fuel guy you use and get info if needed.

MFI is super simple once you get the basics and a baseline. Makes carbs look like rocket science degree is needed.LOL

While I do all my own stuff(30 years doing it) I suggest taking one of two mentioned above steps for getting started it will save head aches and make you a MFI guy for life.

If any questions PM me and I will try to help.

I use O2 and I slow down s little (.02) at 12,5 and I am fastest around 11.5 ( gas scale).

Thanks for the replies. I alsked mainly because I was seeing rich on O2 and builder seeing lean on EGT. Car ran consistent but we both think could be quicker and faster. My O2 is in collector and is useless except wide open throttle. Egt’s are in #7 and #8 just installed exactly as computech instructions stated. Egt was around 1180 first hit, moved down to 1050 ish after we fattened it up. O2 showed 4.8-4.9 no matter what we did on tune. Performance stayed the same except when we moved shift point. My next step was to make a big junp fatter and see if performance improved or fell off but we didnt get to run the second day that we were planning on.

I have had EGT,s got rid of them totally useless on my car. I now have 8 O2 and it is much more reliable. I also use the gas scale and on the dyno and on the track my car works best at 12.9 to 13.1. One other thing you may want to know is with mechanical injection you may need different nozzles in every cylinder to get perfect tune up.
Good thing about alcohol is that it does not have to be perfect.

Stephen,
I ran into a similar issue showing lean on EGT. Turns out I was overly rich and was burning fuel in the tubes showing increased temp. After chasing for some time we figured that much out. Leaned it out a touch and got the most out of what we have. 582 ci with a toilet injection on a 1900lbs dragster, my sweet spot is 1120-1140 on the EGT.

Don't matter if your using EGT's or O2's, where it runs the best is the number! Between sensor locations and calibration, it is what it is! and it don't matter that someone else's is different. Time slips don't lie!

And for 02's in the collector, it's just an average of that side of the motor! You will have rich and lean cylinders! Put a bung in the pipes and see for yourself!

Here is my .02, to me the egt is slightly rich,that would put it 1280 in 1/4.also I think the O2 is showing slightly rich.your tuning changes will likely make more change in 1/4.from from et and mph it looks ok.time to strip weight off the car.

quote:

Originally posted by TOP38:
Don't matter if your using EGT's or O2's, where it runs the best is the number! Between sensor locations and calibration, it is what it is! and it don't matter that someone else's is different. Time slips don't lie!

And for 02's in the collector, it's just an average of that side of the motor! You will have rich and lean cylinders! Put a bung in the pipes and see for yourself!

I understand that just fine, I was hust wanting ballpark numbers to see what everone else was seeing. I personally have never messed with egt, and used O2 before just to give myself an idea of how the tune changed throughout the run. This is a completely different O2 set up, grid instead if stand alone, so I inow it can read totally different. I felt i could still get an idea of where we were at if my numbers where in the low end of the range of numbers other people see or the high end.

Rusty, not a lot of weight to be cut off of this thing except between the steering wheel and the seat, and that is 31 less than it was in March.

quote:

Originally posted by Stephen Hughes:

quote:

Originally posted by TOP38:
Don't matter if your using EGT's or O2's, where it runs the best is the number! Between sensor locations and calibration, it is what it is! and it don't matter that someone else's is different. Time slips don't lie!

And for 02's in the collector, it's just an average of that side of the motor! You will have rich and lean cylinders! Put a bung in the pipes and see for yourself!

I understand that just fine, I was hust wanting ballpark numbers to see what everone else was seeing. I personally have never messed with egt, and used O2 before just to give myself an idea of how the tune changed throughout the run. This is a completely different O2 set up, grid instead if stand alone, so I inow it can read totally different. I felt i could still get an idea of where we were at if my numbers where in the low end of the range of numbers other people see or the high end.

Rusty, not a lot of weight to be cut off of this thing except between the steering wheel and the seat, and that is 31 less than it was in March.

If you have a data logger with O2, look at the curve throughout the run, that is also important. If it's not relatively flat there is room for improvement. Remember MFI is dumb, it does not listen to the motor like a carb does! it just sends fuel based on rpm whether the motor wants it or not!

quote:

Originally posted by Stephen Hughes:
First off,I understand that you should tune off the time slip and tune for best performance. That being said what are some ballpark EGT numbers and A/F ratios you guys are seeing in alky injection and running 1/8 mile? Reason I ask is I have both and my builder is comfortable tuning with egt and i’ve always used O2. My set up is 598 conv head deal topped with terminator, ran 4.78 at 146 first time out since rebuild and a few combo changes @ about 2000 lbs.

AF for the last 1-2 seconds of the run = 4.8-5.2 (on meth scale, if using gas multiply gas number by .438)

EGT last second of the 1/8 mile = 980-1020 (if you are using a EGT that just records max, glance at gauge at 600ft and make sure that close to your max as MFI is notorious for momentary spike of 1300+ when lift)

maybe Scott Offerman will jump in with more info.

this is a copy and paste from a rant I went on about 2 years ago. I am better now, the meds are working.

When I have a engine on my dyno, I DO NOT use EGT’s to tune a engine. I use BSFC and O2 sensors (with ALL fuels) but even with that, I pull the plugs ever time I make a timing change. I use EGT probes to tell fuel distribution and other things, I never use or heavily rely on EGT as A/F Ratio determination
Using the EGT probes for fuel distribution studies is their greatest value.
You can't ask some other racer what EGT is best for you .
example= no matter how well you tune a 9:1 normally
aspirated engine, its EGT's will be higher than a similar
properly tuned engine with 15:1 Compression Ratio .
....no matter what you do , the 9:1 CR engine is going to have
higher EGTs because it will waste heat out exhaust more than
a 15:1 engine, or any CR higher than the 9:1 CR reference point .

If you asked a group of racers that all had their engines
perfectly tuned and maxed out with the best possible ignition
timing curve and A/F Ratio ....
one racer might say 1350 deg F ,
another might say 1250 deg F ,
another might say 1150 deg F,
another might say 1050 deg F
.....they could all be correct and have the very same A/F Ratios
.....the varying EGTs depending primarily upon Compression Ratio,
Volumetric Efficiency percent % , Combustion Chamber/Piston
top design and camshaft design.

Another thing you have to watch out for is
where are you placing the EGT probe??
1-at 12 o'clock or so ...
2-How far away from heads exh port flange ???
3-How deep is the EGT probe protruding into header pipe diameter ????
4-EGT probe type and response time

all these factors greatly influence EGT temps making
it very much impossible to directly compare EGTs between racers
if no standards are set to probe placement

So basically , if you walk around the pits at a National Event
and ask the SS racers that have CR from 9 to 11:1 mostly ,
they'll tell you 1250 to 1350 EGT and maybe a few at 1450

you ask the ProStock and Comp guys with 16+:1 CR
they'll tell you 1000 to 1150 deg F
maybe some of the very large Mountain type engines
with HiCr tell you 850 to 1000 deg F EGTs

Hi Compression Ratio = Lower EGT temps

Lo Compression Ratio = Higher EGT temps

Correct ignition advance(32+ to 40+ ign deg range)= Lower EGT temps

Wrong ignition advance ( below >25 or so deg range)= High EGT temps
..... burn slower and later in stroke , continuing to burn
while exhausting and if severe...cycling/snowballing into rising
coolant temperatures, preignition, then detonation.



bottom line is, unless you have a dyno, you need to tune your car by reading plugs, time slip and adjusting from there.

Joe

quote:

Originally posted by Greg Kelley:

quote:

Originally posted by Stephen Hughes:
First off,I understand that you should tune off the time slip and tune for best performance. That being said what are some ballpark EGT numbers and A/F ratios you guys are seeing in alky injection and running 1/8 mile? Reason I ask is I have both and my builder is comfortable tuning with egt and i’ve always used O2. My set up is 598 conv head deal topped with terminator, ran 4.78 at 146 first time out since rebuild and a few combo changes @ about 2000 lbs.

AF for the last 1-2 seconds of the run = 4.8-5.2 (on meth scale, if using gas multiply gas number by .438)

EGT last second of the 1/8 mile = 980-1020 (if you are using a EGT that just records max, glance at gauge at 600ft and make sure that close to your max as MFI is notorious for momentary spike of 1300+ when lift)

maybe Scott Offerman will jump in with more info.

I’ve talked to Scott about my set up. I’m not not looking to make wholesale changes to my set up based on the given data, I just wondered what other people see on their set ups.

As I and others have said the truest reading is plugs.They know more about whats going on in cylinder than anything else. ET tells you what makes best power every where and mph tells you how much power you are using to get job done.

Rather o2 or EGT's they are just another tool.Use them correctly and they will serve you well.

As cpl have said you will get lots of different views and most maybe right its just how they go about making them work. Some times there is such thing as too much info.

Joe here (SR440) has been a huge help for my car and tune up. I have made about 100 pulls on his dyno with different motors through the years and have learned so much. Now everyone here has got some good information and most of it is right.

In my opinion the best way to tune your motor is on the dyno with a good operator who has all of the O2 sensors. With that said the dyno is not the same as on the track. My tune up is completely different on the track. The reason for that is I have a Enderle hat injection and it is getting air forced into it at higher speeds. That makes the rear cylinders require more fuel. I used same O2 sensors and headers when I dyno my motor as I do on my car. I do this to help keep all variables to a minimum.
I also agree with what someone said about using the data at the end of the run. In my opinion it is more reliable after it has had a little time to stabilize and it is set rich at low RPM.
I trust my O2 on my car but I also believe in getting all information you can and using all of it to make a tuning decision. I look at time slips,
weather, plugs, water temp, O2 and oil temps to make decisions. I have also had some O2 sensors fail so if you have anything that looks out of place verify it by other means.

As for EGT's I was told years ago to put probe 1.5 inches from flange on header and get 1050* in 1/8 and 1100* in 1/4 mile and it will be perfect. Well when I did that it was so fat it would barely run. With my EGT's had to be at least 1350* in the 1/8 to run and it was not linear or predictable. The O2 numbers are much more reliable so I have removed the EGT and do not even use them any longer.

What ever you use EGT or O2 tune to get best ET and then use those numbers to tune to from there. For instance if your best ET's is with O2 at 12.7 then that is what you want your O2 to stay at as weather changes. Denser, cooler air add more fuel but you would still want the 12.7 O2.

Curly, the bottom of your post is how I normally go about it, I was simply wondering what other people see for numbers with EGT and O2. This is the first time i’ve ever had egt’s on my car in 24 years of racing. I’ve used O2 before but added it to a well established set up and used it as reference, same as I intend to do now once we get the most out of it.

quote:

Originally posted by wideopen231:
As I and others have said the truest reading is plugs.They know more about whats going on in cylinder than anything else. ET tells you what makes best power every where and mph tells you how much power you are using to get job done.

Rather o2 or EGT's they are just another tool.Use them correctly and they will serve you well.

As cpl have said you will get lots of different views and most maybe right its just how they go about making them work. Some times there is such thing as too much info.

What does a properly tuned methanol engine plug look like?