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ECUflash Max timing on 91

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
Out of curiosity is 7* of timing at spool up and 10* up top normal for 20psi boost on 91 from a 20G turbo? Seems kinda low but everytine timing is added it picks up signs of knock. Egt will peg 1500* at the end of a run and that's at 11.2afr
 

danl

Proven Member
617
27
Apr 8, 2002
Severn, Maryland
What rpm is your 7 deg of timing coming in? That may be a bit much. The timing out the back door will rely on factors like iat’s, compression, etc.

As a reference, my car comes in at 4-5 deg at 3500 rpm and it’s 12-14 deg at 7000-7500 rpm. 20 psi, roughly 100 octane, iat’s are 5-10 degrees above ambient, big 16g, 20 psi. The engine has lots of compression and lo

Don’t try to run timing numbers the engine won’t take. Always run 1-2 degrees less than knock threshold to maintain consistency. They tend to run better passes that way.

11.2 afr is good. EGTs don’t mean much unless you are running them in each exhaust port and have reference numbers from a dyno session.
 

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
My low timing is about 4400rpm and slowly climbs. compression is 9:1. It does need a bigger intercooler as Temps start to climb
 

1990TSIAWDTALON

Moderator
8,593
4,497
Nov 14, 2013
Independence, Kansas
Until you go to higher octane fuel, you are just about at the limit. If you push it too far you run the chance of melting a piston at the ring lands.
Now put E85 in it and you can bump that top timing number up to 14-15 safely, but it won't "show" knock until it is too late, so I keep mine around 15*.
My son added 4* of timing to his already "hot" timing table and did that. You can see it happen HERE.
I have done it myself, thinking I could run more than 5* on gasoline. I moved my knock sensor up out of the range of RPM's I was running and I ruined 2 cylinders. Lesson Learned by us both.
 

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
Ok so looks like I'm going to leave it alone. Iv melted a few pistons in other engines and scared to do it again
 

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
It's crazy you can see when the piston let go!
 

1990TSIAWDTALON

Moderator
8,593
4,497
Nov 14, 2013
Independence, Kansas
Oh for sure.
It was a FRESH build and would have got him the 10.99 he wanted if he had just left it alone after we got it off the trailer is the sad thing. I can fix the motor, although it has some aluminum slag in that one cylinder that I will have to clean out. I saw the motor in his garage this last weekend and told him to let me re-rebuild it but it hasn't made its way out here yet AND.....IT'S FREE to him since dad builds them. ;)
 

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
Can't beat free! Ya I have alot to learn. I'm no beginner but I'm never gonna say I know more than others as il always learn something
 

jed344

Supporting VIP
1,147
242
Jan 10, 2008
Waterville, Iowa
So many factors that decide timing. When on pump fuel knock will almost always tell you when limit is, on e85 its not so simple. When on pump i tune till knock, when on e85 i tune till MBT and read plugs. When i remote tune e85 i build a map i feel is safe for set up. For example latest car is a 10:1 motor i built with a 6466 on e85 tested at 87%. I have 5-6 degrees at peak TQ climbing to 12 degrees by 8,500rpm. This is likely 1-2 degrees soft in upper rpm's but without being on the dyno or in person to read plugs its what i expect for this boost level witch is 37psi.
For a low compression motor say 8:5:1 if not knock limited its not uncommon to see 16-18 degrees up top on ethanol fuel. Pump gas well find knock and that is your limit. Sometimes you can go richer on air fuel and go little more.
 

Pvauto

Proven Member
31
9
Sep 25, 2021
Campo, California
Iv limited boost to 22psi and dropped afr to 10.9 or so. Timing is at 10 up top at the moment and will hit 1600* egt pretty quick.this 9:1 compression motor is a blessing and a curse when running pump. I dont have access to e85 locally so I'm stuck running crap California 91
 

1990TSIAWDTALON

Moderator
8,593
4,497
Nov 14, 2013
Independence, Kansas
Don't try to push her. I regret doing it but at the same time, I wouldn't have had to build the cool ass motor I have....ROFL
Gasoline is the same here in the middle of the country, its crap. I am very luck to have an E85 station about 20 miles away and I can bring some home eveyday since I pass by it going to work in my DD 38mpg Saturn SC2. :thumb:
Keep the timing conservative to avoid knock is all you need to be worried about and then leave it alone. Be thankful you can get more than 5* like here.
 

Vegas Smith

Proven Member
4,747
2,605
Dec 2, 2002
Houston, Texas
So many factors that decide timing. When on pump fuel knock will almost always tell you when limit is, on e85 its not so simple. When on pump i tune till knock, when on e85 i tune till MBT and read plugs. When i remote tune e85 i build a map i feel is safe for set up. For example latest car is a 10:1 motor i built with a 6466 on e85 tested at 87%. I have 5-6 degrees at peak TQ climbing to 12 degrees by 8,500rpm. This is likely 1-2 degrees soft in upper rpm's but without being on the dyno or in person to read plugs its what i expect for this boost level witch is 37psi.
For a low compression motor say 8:5:1 if not knock limited its not uncommon to see 16-18 degrees up top on ethanol fuel. Pump gas well find knock and that is your limit. Sometimes you can go richer on air fuel and go little more.
I've had the talon tuned by multiple well-known tuners and this is how they do it on remote tunes^^. You just go a little conservative on the timing and throw all the boost you want at it. If you're upset about the slightly lower timing then you shouldn't have gone remoted-tuned!
 

jed344

Supporting VIP
1,147
242
Jan 10, 2008
Waterville, Iowa
Without dyno and being in person to read plugs with e85 there nothing we can see on other end. So build a safe map and toss the boost at it.
 

Imback

Proven Member
1,171
31
Nov 8, 2006
Long island, New_York
^ This. As far as the OP original question. The few cars that i've tuned that requested to stay on pump gas have had around 8-9sih timing up top. One of them being a 20g car as well. Each car is diffren't and there is no set #
 
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