+20% Injectors: Lower EGT's

[85GLHT-Omni]

Interesting finding:

I just installed a new set of +20% injectors and my EGT's dropped significantly. Cruising at 65-75 MPH dropped EGT's from 1400+ to <1300F. Max EGT's at WOT are a touch over 1400F...a change from scary 1550F temps.

Also, I'm running at stock fuel pressure. Idle is good and no black smoke. I'm using a TU cal set to 15 psi. The before numbers were with a new set of 804's.

The car is an 85 GLHT with a TII conversion.

Car feels as strong as ever.

[cndnGLH]

Was the TU unit cal-ed for the +20's?

[Una]

Frankly, when I do my cars, I specifically tune them to run lean at cruise. It makes for better gas mileage and the car isn't under enough load to damage anything while cruising (generally 10-17" of vacuum). So it's not that bad of a thing for EGT's to be fairly high under cruise. Do you have an A/F gauge? You may have pushed that cal right out of it's adaptability range, and it's unable to fully enter closed loop mode now.

[85GLHT-Omni]

A/F gauge bounces around under cruise as it did with the 804's. The Cal was setup for 804's.

[turbovanman]

Seems the TII calibration likes the +20's, from what I have read!

[TurboShadowES]

mine is likeing my +20's alot... my base is at 42 psi and im running 1500 going down the freeway. Im pretty shure my gas milage has went up since the swap.

ims till running kinda lean at 17psi even with the 1.7:1 RRR... Ill just turn the base up more, lol.

[unclejemima]

Quote:

Originally Posted by Una You may have pushed that cal right out of it's adaptability range, and it's unable to fully enter closed loop mode now.

I dont quite understand this? Can you explain more?

Pretty much, you are now adding 20% more fuel than would normally be used, but its amazing that you dont notice a decrease in idle or fuel economy. Very neat... A guarenteed safe in terms of extra fuel...
Did you notice a power difference? My guess is your power may have slightly came down, being you are not at the best fuel/air ratio? Can anyone confirm this?

Verrrrrrry interesting

-mark

[unclejemima]

Mabey the TU guys would be able to best answer this question? Chris, where are you
-mark

[85GLHT-Omni]

Off to the Dyno today. I'll bring the 804's and do a swap if time permits.

As for TU, they have stated that my cal wasn't setup to run with the +20's. I've got about a tank of gas burned and I got my obligatory 200 miles, so no significant change in mileage. With more data, I'll plot mileage as a stock T1, TII with 804's, and TII with +20%'s.

IMHO, any reduction in EGT's translates into significant improvements in material properties for aluminum. After ~400F, Aluminum's fatigue capability falls off very fast.

[unclejemima]

Agreed, 85GLHT-Omni. That would be a amazing discovery! And you will actually have dyno results to prove it! Good luck with everything.
I definatly would trade a few hp or worse gas milage for a longer lasting engine!

What do your plugs look like? Do you notice they foul up more? Are they super black?
-mark

[85GLHT-Omni]

Well, now I have results....

Good news, +20%'s yield lower EGT's.
Bad news, +20%'s yield lower performance.

I hit about 180 hp on the dyno today. I was expecting to hit well over 200. The facility probe was off-scale rich. I plan on switching back to 804's immediately. I'm very disappointed with the results.

BTW, plugs look fine.

[unclejemima]

Thats too bad! So the tail sniffer was way off the scale rich?! Well, that answers our questions. Funny your plugs werent soaking wet or black!
Thanks for the info, i'm sure this would have generated quite abit of interest if the results were hp+
I guess we just dont trade HP for lower EGT's.
1550 is ok, 1600 starts to get bad. Your still ok!
-mark
PS
are you going to do a dyno run with the 804's some time in the near future? What are you running? TI, TII?

[jdawg]

Quote:

Originally Posted by unclejemima I dont quite understand this? Can you explain more? Pretty much, you are now adding 20% more fuel than would normally be used, but its amazing that you dont notice a decrease in idle or fuel economy. Very neat... A guarenteed safe in terms of extra fuel... Did you notice a power difference? My guess is your power may have slightly came down, being you are not at the best fuel/air ratio? Can anyone confirm this? Verrrrrrry interesting -mark

I agree with this, youre not adding 20% more fuel unless the fuel pressure is tuned or the comp is cal-ed for it. Kinda like I talk to Honda guys all the time that say i spent x on bigger injectors for more power, i kinda snicker, u have to bump fuel pressure up or get a re-cal. Its kinda like comparing water going thru a straw compared to a garden hose, at the same pressure it kinda just drips out instead of squirting. There should be a loss of "velocity" right? Or am i just over my head?

[turbovanman]

Quote:

Originally Posted by jdawg I agree with this, youre not adding 20% more fuel unless the fuel pressure is tuned or the comp is cal-ed for it. Kinda like I talk to Honda guys all the time that say i spent x on bigger injectors for more power, i kinda snicker, u have to bump fuel pressure up or get a re-cal. Its kinda like comparing water going thru a straw compared to a garden hose, at the same pressure it kinda just drips out instead of squirting. There should be a loss of "velocity" right? Or am i just over my head?

You are actually gettting 20% more fuel at the same fuel pressure. You will only see a gain if the engine was running lean.
I have test our injectors down to 20 psi and they still have the correct spray pattern.

[jdawg]

yeah i figured i was at a loss, prolly would be good on a t2 or a 2.5 assuming it was stock, or just runnin a little more boost, i was gonna put +20's in my car (2.2) when i did the headgsket but i feared it would be too rich so i just used stock replacements, mine were pretty cruddy