Boost, EGT and Oil Pres Gauge Readings?

[dongoesby]

I just got my defi link gauges hooked up. I'm not sure the numbers I got from my gauges are within spec for my motor.

Here's setup:
stock s14 sr20 w/ stock exhaust
(except tomei manifold, greddy oil pan and s15 smic core)
4qt 10w30mobile1 + 1qt 15w40mobile1 (for quiet down drained lifter)

defi link gauges: boost, egt, oil pressure, "oil temp"(not set up yet)
*egt sensor mounted on dp, half an inch next to turbo housing
*boost "t" to fuel regulator hose
*oil pres mounted at the oil filter housing
*oil temp mounted to greddy oil pan (still suffer wiring problem)

hwy cruising 65mph:
egt: 1100 F+ (normally near 1200F @70mph+)
oil pressure: 70 psi

idle:
egt: 800 F-
oil pressure: 20 psi (after warmed, ~60 psi cold)
vacuum: -60kpa (-8.7psi)

under 10psi boost
egt: 1400 F+

under 14psi
egt: 1500 F+ (full throttle at 7k rpm)

Do these numbers seem normal? I think mine is running lean at high end and becomes too hot 1500 F at 14psi. My friend's evo never go above 1400 F even under boost.
I heard at 1500 F, it is enough to melt pistons. Is the temperature at exhaust manifold/dp different from engine internal? Does it get hotter when the air gets outside of the engine?

what readings you guys have?

[jr_ss]

Yeah, your EGT's are a bit high... You're running extremely lean at 14psi and even at 10. I'd back it back down to 7-10psi MAX until tuned.

You're vac is low as well. 13inHg is not a healthy motor. Do a comp/leak down test.

Good news though you're oil pressure is awesome at cold and warm.

[dongoesby]

Originally Posted by jr_ss

Yeah, your EGT's are a bit high... You're running extremely lean at 14psi and even at 10. I'd back it back down to 7-10psi MAX until tuned.

You're vac is low as well. 13inHg is not a healthy motor. Do a comp/leak down test.

Good news though you're oil pressure is awesome at cold and warm.

thanks. What would be normal temperature for egt? Is there a number I should never go over such as 1500 degree F? During normal cruising/driving, it usually stays below 1200 degree F on highway (70~75mph). Please note that the egt probe is mounted right next to the turbo housing on dp. Should it reading a tard lower than if it was mounted on the manifold?

I did a little research, and -8.7 psi should be normal for stock sr. I've checked every piping and clamps. I found no leak anywhere. Timing was untouched. The car idle fine at 900rpm. Cold start would jump up to 2100rpm, but slowly down to 900rpm.

It does have a notchy idle jump every one mine from 800~900rpm for about 5 sec. I think this caused by air trapping in the coolant system though. It was worse before I bleed the coolant system.

Any thought welcome.

[z2roll4life7]

Stock Sr's Run 11 Psi from the Factory.....

Also i Though U place the EGT sensor on to the Manifold before the Turbo?
like about 2 to 3 inches from the head on the 3rd or 4th runner You have a tomei Manifold put a Bung on that u should get a better reading

[dongoesby]

Originally Posted by z2roll4life7

Stock Sr's Run 11 Psi from the Factory.....

Also i Though U place the EGT sensor on to the Manifold before the Turbo?
like about 2 to 3 inches from the head on the 3rd or 4th runner You have a tomei Manifold put a Bung on that u should get a better reading

i placed the egt sensor after turbo actually. I tapped a hole on the dp where it was like right next to turbo (less than 1 inch away).

i know on the manifold would give more accurate reading, but really don't want to make a bung on the tomei...

any thoughts on the gauge readings?

[g-via]

(S13 SR/straight pipe/LT-10s)

my cold idle is ~18 inhg = 8.8416 psi

my warmed up idle is 20inhg = 9.824 psi

jr_ss either you or I did the conversion wrong

1 inhg = 0.4912 psi???


EDIT

You know what's weird though...my greddy profec-b tells me that my vac is 99 KPa @ 20 inhg.....something isn't right.

[ILoveJDM]

Originally Posted by z2roll4life7

Stock Sr's Run 11 Psi from the Factory.....

hes talking about vacuum

[g-via]

after quick readings on the interweb

16-20 inhg is a healthy motor.

So, OP, if my conversion is right, your idle vacuum is fine (same as mine)

[jr_ss]

Originally Posted by z2roll4life7

Stock Sr's Run 11 Psi from the Factory.....

Also i Though U place the EGT sensor on to the Manifold before the Turbo?
like about 2 to 3 inches from the head on the 3rd or 4th runner You have a tomei Manifold put a Bung on that u should get a better reading

Stock SR's do not run 11psi from the factory, go research my friend. 7psi is the stock pressure from the T25/T28 turbo's.

Originally Posted by g-via

after quick readings on the interweb

16-20 inhg is a healthy motor.

So, OP, if my conversion is right, your idle vacuum is fine (same as mine)

I didn't do a conversion, I forgot/didn't realize he was in metric.

[dongoesby]

Originally Posted by g-via

after quick readings on the interweb

16-20 inhg is a healthy motor.

So, OP, if my conversion is right, your idle vacuum is fine (same as mine)

yes thank you. But for -8.7psi/.49 ~ 17.7 inhg, I think I am still at the low side.



Does anyone can tell me why my egt is higher than normal?? It is like 1200 deg F when i cruising on freeway last night (@70mph all motor, turbo did not kick in)

[z2roll4life7]

Originally Posted by jr_ss

Stock SR's do not run 11psi from the factory, go research my friend. 7psi is the stock pressure from the T25/T28 turbo's.

Haha Tell me to Do Research The Stock WasteGate Spring on
t-25 and t-28 is 7 Psi but from the Factory they come
with a Air Restrictor that goes in between the Vacuum line from the cold pipe to the WasteGate that bumps
Boost to 11Psi SmartGuy

[z2roll4life7]

Originally Posted by ILoveJDM

hes talking about vacuum

He was talking About PSI when he was on the Highway hes over 10 psi (Sr from the Factory is at 11 Do your Fucken Research) and hes at 1500 THATs FUCKEN hott the placement of the EGT sensor can have a big effect all i can say is the Right way would to put in on ur Manifold bro also Check Ur Timing

[dongoesby]

Originally Posted by z2roll4life7

He was talking About PSI when he was on the Highway hes over 10 psi (Sr from the Factory is at 11 Do your Fucken Research) and hes at 1500 THATs FUCKEN hott the placement of the EGT sensor can have a big effect all i can say is the Right way would to put in on ur Manifold bro also Check Ur Timing

actually no. Honestly, i appreciate your help for chiming in. But, like lots flame going on now on new zilvia users, please use commas and punctuations...

stock sr t25/t28 does run 7psi without mods, but given the factory boost solenoids are still hooked up, it would go up to 11psi depending on the rpm. It could be another topic for this, but it is not the matter here anyways. I use hks actuator and it holds steady 14psi under WOT. And the egt shows 1500 deg F only at 14psi. When I'm at half throttle (around 11psi), the egt would be around 1400 deg F. And under no boost, cruising at 70mph all motor, the egt is at 1200 deg F.

Any ideas?

[dongoesby]

Just read the DSM forum with great information. I think I might found answers to my own questions. I will post here for future reference for zilvians.

Since DSM people have similar engine (4 cyl. alum block w/ t25/t28), I assume their gauge readings would be relatively effective on sr20. Their average egt readings are 800 deg C (1472 deg F) on 75mph hwy cruising and 900 deg C (1652 deg F) under 11~14psi boost.

Base on their conclusions, 1600 deg F is the highest safe side you should go, beyond that would be asking internal stress or melting. These egt readings are measured from probe mounted on manifold. For probe mounted after turbo should add 100~150 to be approx correct.

Reasons cause egt to change: (thanks dsm forums)
"Retarded timing will raise EGTs. So in effect, running lean still raises EGTs, but not for the right reasons. Also, running excessively rich will raise EGTs due to fuel still burning as it leaves the motor and passes the sensor. Retarded timing raises EGTs the same way. AFR will affect EGT, but to a small degree. The large swings people report are all from ignition timing changes."

[jr_ss]

OP, glad you answered most of your own questions. In my personal opinion, I'd back down the psi levels until you get a tune to make it safe..

That's right the wastegate does pop off at 7psi, the boost solenoid, not the restrictor allows the boost to creep to 11. That is not 11psi all the time, nor the stock pressure. Therefore, the factory boost setting you'll see is 7psi on 99% of STOCK swaps.

[z2roll4life7]

But What i was Getting at is that s13 SR's (wich More people Have) from the factory were Made to run at 11 Psi thats all i was getting at

[dongoesby]

As a future reference for other members. I went further into research and found my EGT reading (1100~1200 deg F) is exceptionally good for stock motor w/ stock ecu.

"We conducted the experiment on Ryan Larsen's '92 Talon AWD. Our baseline run had the EGT probe located in the collector and whenever the car was under load, the EGTs would easily climb past 1600oF (at which point we let off not wanting to damage the engine). After that, a new exhaust manifold was acquired and the EGT probe plumbed into the runner this time. Additionally, Ryan upgraded to a SteveTek High Flow Fuel Delivery System which has been consistently shown to drop EGT's about 50oF. Other than that, everything was kept constant (AFC programming, fuel octane, pump, injectors, etc.)
With the probe now mounted in the runner, we went out for a few runs and found that we could not induce the EGTs above 1410oF!!! Or in other words it ran at least 150oF cooler than when the probe was mounted in the collector (accounting for 50o decrease due to the new fuel deliver system). It is probably a bit more as we could've driven the collector mounted probe temp easily above 1600oF."

data gathered from Stevetek

cheers.