How likely am I to blow my motor running 19 PSI at 18.5 degrees on 93 plus octane booster?

TheFleshRocket

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I have a Gen2 TVS on my '04, and it's a disappointment. Mostly I think it's because my tuner was ridiculously overly conservative. (BBK DBTB, 60# injectors, VMP BAP and MAF, LFP dual-pass HE, 70/30 water/coolant with water wetter)

I was running a 2.8 pulley, which made 19 PSI. The tuner gave me three tunes--93 octane (with what appears to be a peak of 13.5 degrees of timing based on my OBDII scanner), octane-booster-supplemented 93 octane (appeared to be 15.5 degrees), and race gas (appears to be 18.5 degrees). Additionally, the tune pulls timing based on IAT2 very aggressively--I might get full timing for most of one 2nd-4th gear run, but definitely not on any subsequent runs.

The 13.5 degree tune was pathetic. If it was over 500RWHP, it wasn't by much. The 15.5 degree tune was a little better, but probably no more than 530-540RWHP. I started running the 15.5 degree tune on straight 93 and it didn't blow up, but IAT2s were still in the 140-145F range after one pull, so it was pulling timing. (This is in 90+ degree ambient temps, so not exactly optimal.)

In the interest of getting the IAT2s down, I went to a 3.0 pulley which makes 16.5PSI, and started running the 18.5 degree "race gas" tune on 93 + octane booster. This is by far the punchiest configuration--I'd guess 550-560RWHP before it starts pulling timing noticeably--but still disappointing.

I am tempted to go back to the 2.8 pulley and run the race gas tune on 93 + octane booster. I am getting a divorce and may lose the Cobra, so while I'm not purposely trying to blow it up, if I do end up hurting it, it'll likely be her problem, not mine. What do you guys think?

On a related note, if you see a silver '04 Cobra with 35Kish miles in southern Illinois up for sale in the next year or so, it has the following issues, so don't give her top dollar for it:
--head tick (mild but noticeable when it gets hot)
--squeaky throwout bearing
--rear glass tint is starting to peel away
--R888s are shot--great for driving sideways, worthless for putting the power down in first or second (but I still want more now because.. REASONS)
--needs to be retuned (in addition to being painfully conservative and disappointingly slow, it has an off-idle hesitation that necessitates excess clutch slip or it'll try to stall, and it lurches at light throttle / low RPM driving, like stop-and-go)

(This car was tough when it was just a 2.76 Eaton and had great drivability--since then, I've spent north of $5K on a car that's marginally quicker and has drivability issues. I should have just had the Eaton ported and been done with it.)
 

Curt@injected

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IMO That's too much for 93. You could probably get away with 16-17 degrees on that set up but I wouldn't go 18.5.

Are you even sure that is commanded peak? I ask because unless you can see spark without modifiers it's difficult to say. It's possible that tune could command like 20 degrees when cold.
 

DSG2003Mach1

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Are you even sure that is commanded peak? I ask because unless you can see spark without modifiers it's difficult to say. It's possible that tune could command like 20 degrees when cold.

this.

My car will pull timing all over the place based on various temperatures with an absolute max of 14 degrees on the 93 octane tune (but then again this is a 10:1 setup and ~15psi). In hot ass Florida its rare that it sees a full 14 for long if at all
 

TheFleshRocket

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IMO That's too much for 93. You could probably get away with 16-17 degrees on that set up but I wouldn't go 18.5.

What about 93 + octane booster, which is probably 95-96 octane? I'm using a pint of the Klotz stuff with every fillup of 93.

Conversely, you think I can safely run the 16.5 PSI 3.0 pulley and the 18.5 degree tune, on straight 93?

Are you even sure that is commanded peak? I ask because unless you can see spark without modifiers it's difficult to say. It's possible that tune could command like 20 degrees when cold.

I have no idea if that's "commanded peak". I'm using an app called OBD Fusion which just monitors various OBD2 readouts. The one I'm using for reference is called "ignition timing advance for #1 cylinder". I'll eyeball it (or have a passenger watch it) and it'll be at 18 degrees until around 5000RPM, and then it'll go to 18.5 degrees.
 
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TheFleshRocket

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Maybe I'm oversimplifying things, but it seems to me that power output is primarily affected by boost and timing. If some (most) people with TVSes are making 600ish RWHP on 93, then I should be able to turn up boost and/or timing until I get there. I've turned up the timing to the most-aggressive tune I've got, so all that's left is to add boost. SOTP, the car definitely isn't knocking on 600 RWHP so I am assuming that I can safely add more boost since other cars can apparently take it without blowing up.

Feel free to tell me that my assumptions are wrong and that it is dangerous to do what I am thinking about doing.
 

DSG2003Mach1

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What about 93 + octane booster, which is probably 95-96 octane?



I have no idea if that's "commanded peak". I'm using an app called OBD Fusion which just monitors various OBD2 readouts. The one I'm using for reference is called "ignition timing advance for #1 cylinder". I'll eyeball it (or have a passenger watch it) and it'll be at 18 degrees until around 5000RPM, and then it'll go to 18.5 degrees.

To see whats really going on youre gonna need to use your handheld and their actual datalogging software. Then you can see commanded, actual and which setting(s) is/are responsible for pulling timing

Edit: based on your other post you need to see what the car is doing. It might be commanding enough timing to make 600 but if something else is causing it to pull timing you'll never get there. It might expose a bad/weak intercooler pump or who knows what other mechanical issue
 

DSG2003Mach1

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also once you've verified everything I'd put it on an actual dyno instead of this butt dyno business
 

01yellercobra

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Any idea what the A/F is? The tune that came with my car had 12.0 A/F and the time was around 13. It was a very soft tune IMO.
 

TheFleshRocket

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Any idea what the A/F is? The tune that came with my car had 12.0 A/F and the time was around 13. It was a very soft tune IMO.

The AFR is upper 11s. I have a wideband sensor wired up with an alarm set to go off if the AFR gets leaner than.. I think I set it for 12.1:1.
 

TheFleshRocket

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To see whats really going on youre gonna need to use your handheld and their actual datalogging software. Then you can see commanded, actual and which setting(s) is/are responsible for pulling timing

Edit: based on your other post you need to see what the car is doing. It might be commanding enough timing to make 600 but if something else is causing it to pull timing you'll never get there. It might expose a bad/weak intercooler pump or who knows what other mechanical issue

The intercooler pump is nice and strong (lots of flow visible in the reservoir) and there are no vacuum leaks (as confirmed with a smoke tester). I've got an SCT x4 and the associated software, but have no idea how to datalog with it.. well, beyond what the tuner had me to during the remote tuning process. I know that timing is being pulled because of IAT2--and the threshold at which it starts pulling is somewhere in the 120s.

No point in wasting time and money on a dyno at this point--I am positive it's not where it should be. If I'm gonna throw money at a dyno, it's going to be with someone tuning it at the same time.
 

blownfox

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Why not find a better tuner? It's a lot cheaper then blowing up your engine. There is no reason why your car should be making only 500 RWHP on the 2.8 pulley. Every car is different, I'm running a 2.8 pulley and only making 17PSI and I believe my current timing is at 14. I'm still one or two revision from completing the remote tuning process.

Data logging with liveleak will allow you to see the complete picture of what your car is doing. this would only be for a SCT device.
 

cj428mach

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Don Lasotas tuning manual says 18psi with 17 degrees of timing is the max safe limit for 93 Octane. If you add more boost you need to take more timing out. For every change in full octane point you need to adjust boost or timing by either 1 degree or 1lb in the direction.

So if you're on 93 and you run 19 psi you need to drop to 16 degrees of timing.

If you're on 95 octane, you can run 20 psi and 17 degrees, or 19psi and 18 degrees. These are just rules of thumb.

So if you drop to 91 octane you'd go down to 17 psi and 16 degrees, which is pretty common for 91'ers.
 

DSG2003Mach1

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Don Lasotas tuning manual says 18psi with 17 degrees of timing is the max safe limit for 93 Octane. If you add more boost you need to take more timing out. For every change in full octane point you need to adjust boost or timing by either 1 degree or 1lb in the direction.

So if you're on 93 and you run 19 psi you need to drop to 16 degrees of timing.

If you're on 95 octane, you can run 20 psi and 17 degrees, or 19psi and 18 degrees. These are just rules of thumb.

So if you drop to 91 octane you'd go down to 17 psi and 16 degrees, which is pretty common for 91'ers.

this quote is dangerous because the compression of the motor has been left out. Put 18psi and 17 degrees on a high compression motor with 93 and you'll need a broom to clean it up
 

TheFleshRocket

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Don Lasotas tuning manual says 18psi with 17 degrees of timing is the max safe limit for 93 Octane. If you add more boost you need to take more timing out. For every change in full octane point you need to adjust boost or timing by either 1 degree or 1lb in the direction.
So if you're on 93 and you run 19 psi you need to drop to 16 degrees of timing.
If you're on 95 octane, you can run 20 psi and 17 degrees, or 19psi and 18 degrees. These are just rules of thumb.
So if you drop to 91 octane you'd go down to 17 psi and 16 degrees, which is pretty common for 91'ers.

Don Lasota is who tuned my car, and it's a pooch. So, yeah.

And it has apparently-unsolvable drivability issues.

This car has been nothing but a disappointment ever since the blower swap, and a lot of it is due to those two complaints.
 
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cj428mach

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this quote is dangerous because the compression of the motor has been left out. Put 18psi and 17 degrees on a high compression motor with 93 and you'll need a broom to clean it up

Thats true, he calls that out for a stock 03-04 Cobra.
 

Fopar

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Don Lasota is who tuned my car, and it's a pooch. So, yeah.

And it has apparently-unsolvable drivability issues.

This car has been nothing but a disappointment ever since the blower swap, and a lot of it is due to those two complaints.

What kind of drive-ability issues? Are you running a return fuel system or stock style?

Don't feel bad on the timing, I'm only running about 12-13 peak at 17 psi here cuz of our CA 91 octane swill. More timing only gets you so far btw, people don't realize there's a thing called max brake torque timing... meaning even if you have the octane to support it, more timing will peak, then start giving you less power (and more bearing stress). A big part of how much power you make is the inlet temps... There's a significant power difference when your IAT2s are high... you might consider trying to lower those if you want more power.
 

cj428mach

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What kind of drive-ability issues? Are you running a return fuel system or stock style?

Don't feel bad on the timing, I'm only running about 12-13 peak at 17 psi here cuz of our CA 91 octane swill. More timing only gets you so far btw, people don't realize there's a thing called max brake torque timing... meaning even if you have the octane to support it, more timing will peak, then start giving you less power (and more bearing stress). A big part of how much power you make is the inlet temps... There's a significant power difference when your IAT2s are high... you might consider trying to lower those if you want more power.

Thats true on MBT but you're a long way from it. You could easily have a couple more degrees even on 91 and see some good gains.
 

Fopar

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For sure, I'm playing it safe tho, CA 91 is worse than other states (no joke). Not only is it worse than other 91s but it's also less consistent. My boss (who used to own a GTR said the GTR tuners literally have a '91 tune' and a '91 CA tune' because of this.
 

Comp04svt

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Well the other downfall to remember too, is the shrouded IAT2 sensor with the TVS, you may be getting some higher than normal IAT2 readings, or readings that are slower to recover, and timing may be getting pulled quicker as a result too. Is E85 a possibility?
 

wckdvnm

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For sure, I'm playing it safe tho, CA 91 is worse than other states (no joke). Not only is it worse than other 91s but it's also less consistent. My boss (who used to own a GTR said the GTR tuners literally have a '91 tune' and a '91 CA tune' because of this.

Interesting statement, I’ve heard from multiple people CA 91 is the most consistent as far as octane due to the stricter emission standards.
 

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