g8tor20

Hey guys. Stock (except for Crawford h/f Cats) 2005 G35 Coupe owner here. Still a newbie with this FI thing but have another issue. I have spoken with a few of you guys privatly but wanted to get some more opinions. I have the Vortech 3.12 installed and tuned. I also have the Zeitronix gauge which has given good data loggings. My EGT temp at highway cruise (80mph) is ~710 Celcius. On some hard runs and multiple gears, I get EGT's past 900 C (Peak of 920 so far). I have not run it hard since I have dicovered this and am getting a re-tune this Friday to be sure. My gauge is one inch from the flange on the drivers side. My question to those who have had high EGT issues, what should be done to get it back down? Some suggestions I have received:

Advance Timing a few degrees
Add more fuel
Check Cats / Exhaust for unwanted back pressure

I called the Dyno place and he thinks retarding timeing is what we should do. I thought the opposite. What do you uys think?

TIA

Jason

g8tor20

And just to clarify... 920C is 1688F!!!

amolaver

iTrader: (1)

Considering where you're probe is, I don't think that's that bad. My WRX, completely stock powertrain had Defi BF's added w/ the probe in the manifold, and I'd see temps like that. In fact almost exactly like that. One-off (street) full throttle runs would be ~900c. Track time would push it up to 910-920c. I was wondering if I was going crazy, and it was degrees F, but since the BF's don't (or didn't at that time) come in fahrenheit, it had to be C.

ahm

booger

iTrader: (6)

My first thought was that your probe was down by the collector so you maybe running hotter than that . Some one with more know how on it should chime in . But would it be running hotter because the probe is being hit with the exhaust pulses from all 3 cyl. , one after the other ? Do you have the probe at the collector ...or up closer to the head on one pipe ?
My probe is 1 inch away from the exhaust port . I get high way cruise [ 70mph ] temps at 690 C. to 710 C. and on hard pulls to 6900rpm...temps of 755 C to 780 C.

g8tor20

When I called my installer (CP RACE) to see where it was at....he said it was on the drivers side on the downpipe about once inch from the flange. Thats was as close as you can get it.

My Cruise temp to 700 doesn't bother me. Its the WOT temp of 800-900+ that concerns me. From my readings of other posts....this is way too high for the VQ. What bothers me is that CP Race pulled back my tuning runs and the a/f and timing looked good. Did something happen with the 2005 engine timing that would made tuning different that previous years? (I have the 280 hp AT and not the 298 MT which, I believe, has the exhaust timing). Its tough to trouble shoot this. Like I said....I'm biting the bullett (and several hundred bucks) to have this re-tuned to see if I can get that temp down. Better safe than sorry I guess....

Gman2004

iTrader: (8)

you can't compare your EGT's to someone elses. depending on the probe location they will vary greatly. Example I see 400-500 when cruising. the thing to look at is that you are always at the same temps. If you normally see 700 for cruising and 800-900 when you are running that is fine as long as it is that way all the time. if all of a sudden you start seeing 1000-1100 when running it then something is wrong. you are worrying way to much about your set up. just go out and enjoy it. your car is fine and does not need to be re-tuned.

Badmonkey

iTrader: (9)

Some good info for you.

https://my350z.com/forum/intake-exhaust/137926-exhaust-gas-temperature-de-mystified.html
https://my350z.com/forum/forced-induction/136643-egts-with-fi-what-are-yall-getting.html

g8tor20

Thanks for the links. But if you read these posts...all of you FI experienced people are running way below 1500 at WOT...usually about 1400. I am way above 1600 and approach 1700.

As for Gman's comment...it does always stay the same...but dont you think its possible that its too high to begin with. Maybe the status quo was too high. I wish I could just enjoy this thing but I worry bout alot of things. This is my daily driver. I think once I figure out this EGT problem, assuming there is one, I'll have a blast.

luanda

I took a preventative hit up-front and did the following to keep engine temps down....

- shoehorning an oil cooler on the passenger side in-between the intercooler and the rad.
- went with a Koyo Rad.
- went with SPAL 16" medium-duty and 13" fans

You may be fine with the EGT temps, but while they may not cause a major catastrophic failure, it may shorten the life of your baby's engine....on that basis I believe stuff like the above ends up paying for itself in the long run.

350Zteve

iTrader: (6)

Get rid of the cats and see what it drops to. Is should drop quite a bit.

UnderPressure

iTrader: (4)

Exactly, you are still running the stock exhaust as well, correct?

Change that stock bits out to something that will flow enough to evacuate the exhaust gases. You are pushing ~1.65x the amount of air volume the stock system was designed to handle. Not to mention the significant increase in heat generated. Remember only ~33% of the combustion process goes towards creating the force exerted on the piston. A small % goes into light energy and the rest is HEAT. By increasing the air volume ~65%, you have increased the amount of heat energy ~65% as well. Yet your tring to evacuate this thru an exhaust system that was sub-standard to begin w/.

Let the engine breathe. It needs an exhaust.

g8tor20

Will just an exhaust do or do I need headers too?

UnderPressure

iTrader: (4)

If you can afford to do both headers and exhaust, do both. If you have to choose. Upgrade the exhaust first then headers later. I suggest something that is @ least a true dual exhaust. Nothing w/ a y-pipe or single exhaust. We have seen these be very restrictive @ higher HP levels.

g8tor20

Vortech said that they design their blowers to be installed on bone stock cars. Assuming this...and the fact that I added the crawford h/f cats, should mean I shoudl have less back pressure than the Vortech was designed and intended for...no?

theking

iTrader: (3)

That would be true if you had the stock pulley but you have a smaller one. Get a new exhaust. Like i told you, I have a borla td for sale.

UnderPressure

iTrader: (4)

But you have had the tune changed from the stock Vortech tune. Vortech's stock tune is very rich and timing retarded. This will produce less heat energy than the setup you have now. You have had the tune changed to optimise power output of the engine setup. Fuel has been taken away and timing added to create a more optuimum combustion process.

Not to mention probably 98% of vehicles that have superchargers attached to them have an upgraded exhaust. So Vortech kind of takes this into consideration. They just kind of assume the car has an upgraded exhuast system.

The stock exhaust system on the Z is inadiquite for even a stock Z. The design is intentionally restrictive to produce a tendency to run out towards the top end of the rpm range. This helps keep the stock motors, in stock form, together thru their warrenty period.

Imagine that your running a marathon. You can breath in thru your nose but only breathe out thru your mouth. And your mouth is taped shut. All you can do exhale thru is a straw poked thru the duct tape. How do you think your going to perform? If you walk you might just make it. Run and your going to end up in convultions on the side of the road with little kids and dogs staring @ you. Laughing....

This is what your motor feels like right now. Let it breathe...

palmerwmd

My EGTS are around 700C at steady 80 mph cruise and 750 C at 90 mph cruise and 790C at 105 mph cruise ( must eb cruise not WOT if WOT then 850C)

Have seen a high of 895C once, but that was only once ever.
usually see 880C on 0-130 mph WOT romp.

When I removed a restriction form improper installtion of AAM highflows , EGTs; dropped by 15-40C depending on driving condtion.

Fred..

g8tor20

Well...I may try and install a Borla TD Exhaust before my Friday Tune. Between the two...I should get my EGT's down a bit even if it means a loss of boost and/or power.

UnderPressure

iTrader: (4)

I'm not real sure what part of this your not understanding.

By replacing the stock exhaust w/ anything better you are going to see much lower EGT's and a power increase. Whoever is filling your head w/ all these ideas about power loss and tuning theory is dead wrong. The tune currently on the car is fine as the car sits now, but will be much better once the car can breathe. Install the exhaust and drive the car. It will be a noticable improvement.

While you are installing your exhaust inspect the cats and make sure they are not damaged or cracked.

Badmonkey

iTrader: (9)

Test Pipes.