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Just wondering what's the max EGT your guage shows say,in a 4th gear pull . My EGT probe is located in the first part of the DP and occassionally,i mean sometime, my EGT goes to 660-670*C :eek: with 1.2 bar boost in a 4th gear pull. Though i'm pretty sure it's fine but still thought to ask u all !
Regards. Yasir
 

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My Probe is in the #2 runner and sometimes will find its way up to 1800 degrees F :eek: with no more than 1.2bar

Even at 1 bar it will creep up to 1650-1700 deg.

I think that BPU cars with the little stock turbos get a lot higher EGT's than people realize.

Lately I think timing retard from this crappy 91 Octane gas has been putting EGT's higher than usual. :(
 
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if you have GReddy EGT probe and mounted at top of DP. 680-690C is a standard for 18psi BPU top end pull. anything lower would be either you're running extremely rich, or your probe location is too far off the turbo.

RSA SUpra, I've been having some problem with EGT too...I'm really wanna blame it on shitty 91octan CA gas, but my A/F ratio tell me I'm running hot because of some other problem.
have you checked your A/F ratio lately? right now I'm at about 12.7:1 A/F ratio boosting 16psi only..and my EGT reaches 730C at top pf DP...too hot. but then again, I'm not using GReddy EGT, so the reading might be little different from Greddy/HKS EGT...
 

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Discussion Starter #6
Zerosoul said:
if you have GReddy EGT probe and mounted at top of DP. 680-690C is a standard for 18psi BPU top end pull. anything lower would be either you're running extremely rich, or your probe location is too far off the turbo.

RSA SUpra, I've been having some problem with EGT too...I'm really wanna blame it on shitty 91octan CA gas, but my A/F ratio tell me I'm running hot because of some other problem.
have you checked your A/F ratio lately? right now I'm at about 12.7:1 A/F ratio boosting 16psi only..and my EGT reaches 730C at top pf DP...too hot. but then again, I'm not using GReddy EGT, so the reading might be little different from Greddy/HKS EGT...
Zerosoul,what difference does it make with a different EGT probes :rolleyes: BTW,i think my A/F ratio around 5500RPM is 12.6 as well but i think i would like it to b around high 11's or low 12's ;). I have an old style Apexi AFC and need to dyno my car again ti tune it further !
Regards. Yasir
 
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different gauge reads little different alot of the times. sensors and temperature probes also, especially when its electrical and signals goes thru a unit before final read out. take boost ague for example, I've seen tests with differnt gauges, and some gauge, ex. Autometer, tested to be 10%+ off. therefore, EGT could also be off if its read with differnt set of gauges...eventhough it shoudnt be off by too much.

my A/F gauge reads exactly like the dyno sheet I've have. at WOT about 4000RPM it starts out at around 11:1, then as RPM increases, the A/F ratio becomes higher untill it reaches 13:1 at redline...which is too lean. I read Fields SFC installation manual and it has some good info on A/F on turbo cars. basically we need to be around 10-11:1 range...above that is consider lean. also, EGT should be below 880C before turbo.
 

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Discussion Starter #8
BTW i have Apexi EGT guage with peak hold,warning & memory selection! Is there any way u can e-mail me that info about the EGT stuff as i'm trying to educate my self as well about all this shit ;) However as far as my info goes EGT upto 12.5 around 5500rpm is safe .
Regards. Yasir
 
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http://www.mkiv.com/techarticles/sfc/index.html

I think info starts at P26 and on, it tells you the AVG # we should follow for EGT and A/F.

12.5 is safe i'm sure, but alot of members like to run a bit rich at high-mid 11 for safety..also to gain more power according to the Fields SFC manual when dialed in just right amount.
 

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First of all, Toyota typically designs phenomenal combustion chambers that allow one to run the leaner, more timing advance, andif necessary hotter charge air temps (from running more boost for given intercooler) than most designs while maintaining stable combustion.

Before you look at EGTs, first get your car wideband lambda monitored, your factory nonlinear O2s do not provide good resolution in WOT enrichment (which is why the computer does not even use nonlinear O2s for fuel trim in WOT enrichment mode).

Convert your O2 readings to the A/F ratios. General guideline 10.5:1 to 11.5:1 air fuel ratios if you want OEM-safe tuning: that means no pinging (assuming all other systems are in working order) all the way up to top speed. If your EGTs are going past 1700 deg. F, then lower boost because your knock retard is causing the combustion too occur to late and you could thermally fatigue your exhaust valves to eventual destruction (seen in 2 MKIV JZ motors and one 300ZX TT motor and I'm sure one of the few failure modes in many other forced induction motors). You can back off timing by a PCM reprogram based on the notion that it takes less timing retard to prevent knock that timing retard to stop it. If you refuse to lower boost and also wish to prevent excessively high EGTs then run more octane which will allow you to run more octane.

There are also instances when everything is in working order, boost is at a reasonable level and the motor still pings; cases seen when someone is trying to run very restrictive exhaust...(e.g.: my friend's '94 TT AOD-rebuilt Supra with the stock cats would ping during firm automatic upshifts with a bit of work done to it). My Trans Am was at its edge of detonation on pump 93 when trying to make 579 rwhorsepower through dual 2.5" random tech convertors despite 8.5:1 CR and a sane 11psi intercooled boost.

Finally my rough guidelines (there are many other variables that enter into the precise tuning A/F) for other driving conditions (if you still have high EGTs, run less boost or more octane):

10.5:1-11.5:1 A/F: pump 93, standstart to top-end driving, road race
11.5:1-12.5:1 A/F: race fuel top-end driving or pump 93 hot street driving up to and a bit beyond the quarter-mile, road race with race-gas.
12.5:1-13.5:1 A/F: race fuel top-end driving with exotic exhaust valve materials, ceramic coating the valves, strong ignition system to prevent breakup, tons of power made on lower-boost pump gas setups if you intend on saving the turbos in wear/tear and race only up to quarter-mile, but make sure to have a really free-flowing exhaust (4").
 

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yasir said:
Just wondering what's the max EGT your guage shows say,in a 4th gear pull . My EGT probe is located in the first part of the DP and occassionally,i mean sometime, my EGT goes to 660-670*C :eek: with 1.2 bar boost in a 4th gear pull. Though i'm pretty sure it's fine but still thought to ask u all !
Regards. Yasir
Yasir,

Mine does about the same. I have the APEX'i EGT gauge with the probe mounted in the top of the downpipe as far up as possible. I have set the warning at 750 Celsius and I only go above that in 5th and 6th gear full throttle pulls at boost above 1.2 bar. I have a lot of problems with overboosting so am very careful at the moment. I installed the Blitz SBC-iD boost controller today and I hope that this will be able to keep boost down.

Flavio
 
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Re: Re: BPU with EGT Guages,please respond !

Flavio said:


Yasir,

Mine does about the same. I have the APEX'i EGT gauge with the probe mounted in the top of the downpipe as far up as possible. I have set the warning at 750 Celsius and I only go above that in 5th and 6th gear full throttle pulls at boost above 1.2 bar. I have a lot of problems with overboosting so am very careful at the moment. I installed the Blitz SBC-iD boost controller today and I hope that this will be able to keep boost down.

Flavio
the rule is no BPU should be going over 700C no matter how hard you pull with probe mounted on top of DP.
I've been having problems also with my EGT going over 720C(where I set my warning) at the end of 4th gear hard pull and 5th gear pull.
I have A/F fuel gague with wideband O2 sensor mounted also at top of DP, which shows my A/F to be at 13:1 at the end of 4th gear pull....too lean.

have you pay attention to your A/F or fuel pressure ratio lately?
what octan do you run in your car?

Jonas
 

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Zerosoul,

Isn't the EGT temperature also dependant on boost? Like I said I sometimes overboost very high (sometimes over 1.35 bar).

I will install a fuel pressure gauge this week so I hope this can give me an indication. What should the fuel pressure normally be? I also have the fuel dampener bypass.

I haven't checked the A/F ratio, I will probably get the FJO unit shortly, I'm waiting for info if it can be connected to the Blitz SBC-iD display.

I run super unleaded 98 octane gasoline (don't know how that compares to US gasoline because I think they measure octane levels differently than over here in Europe, anyway I can't get any better gasoline over here).

Flavio
 
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with that dampener bypasses, your fuel pressure will be lower than stock spec so we cant compare our #. but basically the car should idle around 1.8-2.2bar, at 0psi, the car should be at 3.0bar, than when you boost, add that amount of boost on top of 3.0bar FP and you will know how much FP you should be at.
ex, if you boost 1.3 bar, your FP should be at 4.3bar.

I'm using the shittiest gas in USA. 91octan California gas.
I boost about 1.3 bar also, and my A/F is way lean. when I lower my boost to 1.1 bar my EGT drops.I should be around mid 11:1 range.
yes boost effects EGT, but we should not have any problems with our EGT cuz everyone else is running under 700C under the same condition.
 
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