The intake worked out well! 1

[NickB]

That intake i built using your help for the theory went on the engine about 10 days ago, and the engine went in a week ago. I've only been running at 5 psi for the week because i wasn't sure of how it would change airflow characteristics, and i didn't want to blow anything up from running too lean.

Welll... tonight i started tweaking the fuel tables in the ECU. I'm only using a plain oxygen sensor right now, the wideband will be finished and installed within a week or two, so i'm aiming for 0.900 volts as my target, to keep it on the safe side. I had to raise the part-throttle table above atmospheric, it was reading around 0.74, and that helped, so i raised the boost to 7.5 psi. Ran well, but was running a little lean at higher boost, around 0.85's, and would lean out further at RPM's above 4000, which is actually a GOOD sign, in that the intake was flowing more air than expected.

Raised the full and part throttle maps above 7 psi a tiny bit, and richened up the higher RPM bands too. Went a little ont he safe side at 6000 rpm, again, i wasn't sure what to expect.

Third time out, ended up at 10-11 psi, oxygen sensor is reading between 0.88 and 0.91 all the time under boost, EGT's start around 1250 and climb to 1450 depending how long it's being pushed hard, and it pulls steadily to a higher RPM than it ever has before!!!

Used to peak at 3000-3500, and start to drop off around 4000 or so. Now it still hits hard at 3000, but doesn't really start to let up until 5000, and it drops off a little slower than it used to as well. The stock cam in these things is very conservative, and i'm sure that's holding it back a lot.

Oh, BTW, it's painted a really cool gunmetal grey hammertone now, along with the valvecover. It looks great under the hood.

 

[MaxRaceSoftware]

Nick , glad to hear the new manifold worked out for you !!!

Any pictures of finished product on your web site ???

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

http://members.rogers.com/nickboers/100-1759.JPG

It makes for great access to the wastegate, as you can see it right through the hole in the manifold now. I should be putting the 450cc injectors in soon, and retuning the computer with the aid of a wide band O2 sensor and some datalogging hardware i've built.

That brings to mind another question, what kind of A/F ratio do you suggest i aim for when tuning? Should i tune by A/F, EGT, or a combination of the two? OInce i have the fuel delivery sorted out, what about the spark advance? Any suggestions for how to tune the advance for best performance? I have full control over the advance at all times, i just don't know what to do with it, and when to stop.

 

[MaxRaceSoftware]

Nick,
i would tune by the Air/Fuel Ratio
then look at EGT ,

if timing is too retarded , the EGTs will be very high
for a particular A/F Ratio and Compression Ratio/ Boost psi

whats your measured static Compression Ratio and i can give you a ballpark EGT ...also tell me boost psi
*********************************************************

Nick , you could have a perfect A/F Ratio
and then go retard timing , and EGTs can skyrocket even with a perfect A/F Ratio !!!

***********************************************
Nick just for your information....
i've seen a few racers come to my dyno and dyno test their engines ...we make a few pulls, and i tell them from the computer readouts what the A/F Ratio is
1-if i tell them its rich ...they want to increase ignition timing to change the jetting

2-if i tell them its lean, they want to retard ignition timing to change the jetting

then i tell them ,
"How can increasing or decreasing ignition timing "
magically UNSCREW and REPLACE that jet in your carb ????????????

OK, go move the ignition timing where you want to, and we'll make another test .

So we make another test and i show them the test results ...
i ask them ...."did the A/F Ratio change ???"

they say, "according to readouts , NO"

the A/F Ratio remained basically the same, no matter what you do with ignition timing .

what they "perceive" as rich or lean moving the ignition timing is the EGT temps growing hotter or colder depending upon which way you move timing

moving ignition timing will NEVER unscrew and magically replace the jet in the carb with a new jet size !


Nick , on the dyno , after one short dyno test, i know what the A/F Ratio is ...if its in the ballpark ,
i go after ignition timing ...we keep moving ignition timing
a step at a time one way or another, to find best combo of torque/hp...then we go back and play with jet sizes to fine tune ...if you go after jet size 1st with wrong timing,
sometimes exhaust conditions during overlap can affect jetting slightly , if the racer happens to have mostly header specs on edge of being wrong , or intake specs or overlap period on edge of being wrong for rpm range.

then after the engine is tuned for best average torque/hp
curve,....note the EGT temps as a reference !
but only a reference , not the final word in jetting .

every once in awhile, a racer doesn't do a good job of tightening down the distributor ,...we make a dyno test and the engine's egt go up suddenly and power goes down
as the distributor loosens and retards .
the racer says "it leaned out"
i tell him NO, all it did was start burning the same correct A/F Ratio later and was continuing to burn as it went out exhaust port as you were pretty much wasting it
and sort of blow-torching the EGT probes

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 engine but with 15:1 CR engine ....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

Nick, 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 upon mostly CR + Ve%

Nick, you can dyno test the worlds most perfectly tuned engine with the most stable , most perfect A/F Ratio ,
..it might have 1150 to 1250 EGT for an example .......

then dyno test this same engine at zero deg TDC ignition timing advance under full load for a half an hour or so,
...you're going to completely melt the headers off the engine in half an hour, thats is if it last that long and doesn't 1st cyle/snowball into serve preignition then detonation ! all the while its A/F Ratio would be perfect
but the EGTS will have gone thru the roof !!! that is if you still have a roof in the dyno room and it wasn't burnt in the fire caused by the melting headers .

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 infulence EGT temps making it very much impossible to directly compare EGTs between
racers if no standards are set to probe placement

i had one SS-racer with the Lo-Compression Ratio SS350 engine had his probe 8 to 9 inches back from flange and at 6 o'clock position because thats were it fit best underhood of car ..he was trying to make his car run the same EGT temps as his buddy with a similar SS car but the Hi-Comp Ratio SS350 engine with his probe near header flange and about 12 o'clock position ..needless to say, every time he tried to tune engine to same EGTs , his car slowed down drastically from his buddy .

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

Rich A/F Ratios = Lower EGTs (also extremly lean, misfire)
Lean A/F Ratios = Higher EGTs ..burn slower and later in stroke , continuing to burn while exhausting if severe...
cycling/snowballing into rising coolant temperatures, preignition, then detonation.
Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

Ok, you get a little pink star for that one!!

Compression ratio is 8.1:1. Boost pressure is set at 10pi right now, but i will be running it up to 20, maybe even a little bit higher. I understand now how the compression ratio affects the EGT, since the thermal efficiency of a high CR motor is higher, there will be less thermal energy left over, as it's been used to expand gasses and make power. What about a forced induction motor? It would seem that the same % of energy would be wasted regardless of the inlet pressure if the compression ratio stays the same, which would lead me to believe that although i would have an overall dynamic compression ratio of 13:1 running at 10 psi boost, it's going to run high EGT's because of the static CR of the cylinder itself. Looking at the numbers you've given, i expect a ballpark EGT would be 1450-1500.

My EGT probe is a K type from aircraft spruce. It's got a 1/16" dia. tip, 1/8" body, and sits about 40% into the #1 runner from the 1 o'clock position, 1" away from the head surface. I used to have it located at the turbo inlet flange, and readings were 200 degrees hotter there. I moved it to the current location based on what i've seen as being the industry standard. The gauge is a VDO vision series with cold junction compensation, with the circuit modified for realtime response. It had a filter that drastically slowed reaction time, but i pulled the component responsible for the delay out. The gauge will sweep from 1050 to 1350 in half a second.

What A/F ratio is good to start with? I see differing opinions on this as well, some saying as rich as 11:1, and some as lean as 14:1. Also, how lean can something typically be run under light loads? I might as well tune the part throttle maps for fuel efficiency under vacuum if i can.

What happens to the EGT if you advance the timing too far?

I really ned a dyno now, lol. I have full control of the ignition at any rpm and at any boost pressure, so i don't have to settle for the best comprimise between hp and torque, i can raise the torque curve as high as it will go all the way across the board. Same goes for fuel delivery.

Thanks a lot, and i hope to never be racing AGAINST you, lol.

 

[MaxRaceSoftware]

Nick ,
i forgot to mention one of the most important
aspects of EGT tuning ...
Example-> 4 cyl engine

Engine #1 cyl #2cyl #3 cyl #4 cyl
RPM EGT EGT EGT EGT
5000 1350 1250 1300 1325
....
....
8000 1390 1370 1390 1390


Nick..i would be worried about the
Number # 2 Cylinder out of the 4

Nick, look at the "RATE of CHANGE" in EGT temps

Number #2 cyl starts off low , ends still lower than
others but its RATE is quicker

during a short 600 RPM/SEC dyno acceleration test
you might see engines like above example

but if you were actually racing this same engine
in a road course or relatively long race
the number #2 cyl would grow way too hot ,
its EGT would out pace other cylinders and cause failure ???

Look at "RATE of CHANGE" !!!!
also at lack "RATE of CHANGE" in EGTs
=============================================================

Can't tell you what would happen to EGTs if you went
too far advance on ignition timing ....the engines i dyno
we go a few degrees at a time , sometimes moving advance
1 deg at a time on Hi-CR engines ....we've never went past
4 to 6 deg beyond best ignition timing advance for best
torque/hp curve average . i guess from looking at
P-V Diagrams or ECA Charts of detonating engines , the
EGTs would still be lower from over advance timing
because flame travel rate would be very quick with fast rise
in heat/psi release TOO early in cylinder position
for any leverage and by time exhaust occured
at EGT probes, heat exhausted would be less (just a guess ?)

Nick on the dyno ,
i advance ignition timing 2 degrees then make another test
i then look at new dyno data ..if the 1st couple of
RPM increment points , torque/hp are lower than previous tests
and even though we might have picked up a few Torque/HP ...
we then decide if we will go back to previous timing or try
another degree or so . You can see early in the RPM range
if the engine might be on verge of detonating , it will start
to loose Torque/HP in the EARLY RPM increments compared to
your previous test ...its giving you a hint of whats going to
happen .
=============================================================

with a normally aspirated 8:1 CR engine with a good set
of breathing heads = EGT baseline of 1500 deg F

if you think you are getting 13:1 CR with your turbo
then a EGT Baseline = 1289 deg F average for all cylinders
over AVERAGED RPM-range

ZERO-experience with TURBOs on my dyno...
so i'm guessing that your engine might like higher EGTs than
a normally aspirated engine because of Turbo characteristics
it might like higher EGTs than the baseline i'm
suggesting to you .
=============================================================

i've calibrated my SF-901 dyno fuel sensors to GRAMs accuracy
in both channels/lines A & B

but the SF air turbine i don't know and have questions about ??
on my dyno at 600 RPM/SEC acceleration , 14 to 15: A/F Ratio
make best Torque/HP Curve most of time .

corresponds to;
usually 1 full-turn of light-to-medium color on plug's base-ring
after quick engine shut-off when dyno test is over .
with porcelain looking white like it came out of box
your BSFC should be also low at 14 to 15:1 A/F Ratios and
basically in range .36 to .46 depending upon effective-CR and port dynamics
Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

hmmm.... this is all very interesting....

I expect the average EGT should be more along the lines of 1500 than 1300. EGTs have always been above 1450 until i richened it up this week. Based on what information i've found on standard O2 sensors, it's running around 12:1 A/F right now, which would account for the low EGTs i'm seeing. When it leans out towards 14:1, the EGT sits right around 1500-1550. My friends talon (8.5:1) always read around 1550 as well, and got really fun around 1650 when you pushed it too far.

Since i don't have a dyno, i'll do the next best thing i can think of. I'm almost done the datalogger, and since i can record engine speed, i can also record engine acceleration. From there, i can find road torque, and get a pretty good plot of the power output fromthe motor, i just have to get it weighed.

EGTs on a turbo engine are going to be higher due to the backpressure of the turbo. A freer flowing turbine will lower the backpressure and EGT.

Where are you located? Maybe i can bring the car and we ca both learn something, hehe.

 

[MaxRaceSoftware]

EGTs on a turbo engine are going to be higher due to the backpressure of the turbo. A freer flowing turbine will lower the backpressure and EGT.

Where are you located? Maybe i can bring the car and we ca both learn something, hehe.
===============================================

Nick, i thought the EGTs would be higher for best Torque/HP
curve with the TURBO -vs- Normally Aspirated engine even if
both had 13:1 CR
---all i can give you is dyno data from normally-aspirated engines, and see how close it applies .
i was pretty close for 8 to 8.5:1 CR EGTs

Nick go to my website URL at bottom of this post and there is map location

Larry Meaux (meauxracing@mindspring.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

http://www.mindspring.com/~meauxracing/

 

[NickB]

Whoah, that's kinda far....

I'm putting in some larger injectors tonight and will be tuning it some more, i'll let you know how it all goes.

 

[mattsooty]

Excuse me for not reading all of the above.

In my experience as long as you are running 'rich' you should be well below max EGT or BCT. The only question is how much you should lean the mixture off to accomodate fuel consumption targets, the company that I work for do try their best!!! You have to go VERY rich to lose power.

By the way AFR is NEVER affected by spark advance, always check that fuelling is right before going for power with spark!!!

Perhaps I am a way away from what you chaps were talking about but if interested then reply....


MS

 

[NickB]

Yeah, i'm interested, i'm trying to get as many views on this as i can. The more i know, the less likely i am to overlook something, or misinterpret the readings, and break something.

Where are you reading the A/F ratio from? A probe in the tailpipe? I'm reading off the oxygen sensor, and if the timing is retarded a lot, the mixture is still burning on it's way out the head, and osmetimes even the turbo, in which case the oxygen sensor will read lean, because there's still oxygen left that hasn't been consumed yet, but will be as combustion finishes. It can be rich, but read lean...... gets confusing, lol.

Last night i put the 52# injectors in, and it was running a tiny bit leaner across teh board, but it would lean out a lot at high rpm/boost. At one point the indicated A/F ratio went past 20:1, lost power, but nothing blew up..... I found a fuel leak when i got home, i'm thinking it either actually did severely lean out and my chamberwork kept it from detonating, or the knock sensor picked up the detonation, pulled the timing way back, and that's why the indicated mixture went so low.

Going out for more tuning.... thanks for all the help guys!!