question about HFS-1 and meth/fuel ratio

[mrfred]

I've been looking through the HFS-1 manual and reading recommendations on meth/gasoline ratio. If I understand things correctly, when the HFS-1 turns on, it pumps meth at 125 psi with nothing to control flow except the nozzles and the UICP pressure. So when people tune for say 15% meth, what that really means is 15% meth at peak gasoline flow, and at lower gasoline flow (e.g. lower rpm), the meth/fuel ratio could be higher. For meth/fuel ratio set to 15% at a peak fuel IDC of 80%, then at 60% IDC, the meth/fuel ratio would be 20%. Is that correct?

[Richard L]

This is 100% correct.

The HFS-1 is designed for small, fast spooling stock turbos. It operates within a narrow torque band where most knock occurs.

[mrfred]

Originally Posted by Richard L

This is 100% correct.

The HFS-1 is designed for small, fast spooling stock turbos. It operates within a narrow torque band where most knock occurs.

Thanks. Just wanted to be sure I knew what I was doing with someone's Evo. I'm tuning a stock turbo Evo utilizing 0.9 mm and 1.0 mm nozzles in tandem. By my calcs, at 90% IDC on the stock injectors the meth/fuel ratio is ~24%. At say 65% IDC, the ratio is up to 32%. Seems like total overkill, but more importantly, I'm seeing consistent light knock across the rpm range. E85 is known for causing light knock at gasoline AFRs of less than about 11.8:1. I'm wondering if meth causes a similar response when the meth/fuel ratio starts getting as high as what's on this car.

[Richard L]

A 25% afr is really a 20% if you include the meth as part of the total flow. I think you need to find the right m/f ratio for this set up.

Can you tell me what caused the light knock? Timing or Temperature? I believe at 11.8, alcohol burns the fastest. Your timing may not be too aggressive the burn speed compensates the necessity of adding timing.

As soon as you add methanol, the burn speed will decrease due to colder burn. So much liquid is evaporated.

[mrfred]

Originally Posted by Richard L

A 25% afr is really a 20% if you include the meth as part of the total flow. I think you need to find the right m/f ratio for this set up.

Can you tell me what caused the light knock? Timing or Temperature? I believe at 11.8, alcohol burns the fastest. Your timing may not be too aggressive the burn speed compensates the necessity of adding timing.

As soon as you add methanol, the burn speed will decrease due to colder burn. So much liquid is evaporated.

hehe. I just realized that the web calculator I was using isn't giving the right answer. The 1.0 mm + 0.9 mm nozzles in a 30 psi environment should be spraying about 850 cc/min. At 90% IDC, fuel consumption is 1836 cc/min. That gives a meth/gasoline ratio of 45%, or a meth/total fuel ratio of 32%. Definitely seems way over the top.

I'm just getting started on tuning the car. I was initially asked to just fix up the boost control, but I couldn't resist doing some tuning when I realized that the current tune was not optimum. In the as-received condition, it exhibits light knock (5 counts or less with no strong spikes) with extremely conservative timing values. This is true whether I've got the boost set for 30 psi or 18 psi, although there is less knock at 18 psi. I'm just getting started on modifying the timing to see how the car responds, so I don't have any info that really tells me what's causing the knock. Its just my suspicion that the huge amounts of meth are causing it.

[Richard L]

The amount of meths spray can easily be taken into consideratio when you map the AFR. As far as the engine is cocern, it just see it as fuel. The higher meth percentage, the colder the burn.

Before tuning the car, have a look at the AFR, if it is too rich, the burnt rate will be slow and resulting a knock during the end flame period. Please post the AFR value.

[mrfred]

I didn't figure out that the car was setup for logging AFR via the ECU until after I moved away from the original map and dual nozzles. The car is behaving more predictably now that I'm tuning with a single 1.0 mm nozzle. I am currently tuning low boost and the car is making good power runing low 12:1 AFRs at 200 load with aggressive timing. I can induce typical lean AFR knock spikes if I push the tune to around 12.5:1 with aggressive timing. I think I'm going to settle on 12.0:1 or perhaps slightly richer.

[tephra]

yeah I would say that 1.0 + 0.9 is too much for that setup, particularly with the HFS-1... I am assuming it doesn't have a solenoid to control flow?

[mrfred]

Originally Posted by tephra

yeah I would say that 1.0 + 0.9 is too much for that setup, particularly with the HFS-1... I am assuming it doesn't have a solenoid to control flow?

No flow metering solenoid that I'm aware of.

[Richard L]

What is the version number of the DDS3 junction box? If you have a v10, bought recently, it can be configuured as a IDC based progressive system with a reasonable dynamic range.

[burgers22]

Originally Posted by Richard L

If you have a v10, bought recently, it can be configuured as a IDC based progressive system with a reasonable dynamic range.

Can this be done with a v8? Or can the v8 be upgraded to a v10 easily? Is there any extra equipment needed?

Thanks.

[mrfred]

Originally Posted by Richard L

What is the version number of the DDS3 junction box? If you have a v10, bought recently, it can be configuured as a IDC based progressive system with a reasonable dynamic range.

I forgot to answer your question from before. Its a v8. Interested in hearing your response to burgers22 question.

[Richard L]

On the v10, the FIA (fuel injection amplifier) is built into circuit board.

To upgrade to v10, (PWM-V) from, v8a and v9 to v10 requires:

1. v10 junction board
2. Dash gauge change (RJ45 equipped).
3. Medium speed inline valve to the latest medium high speed valve (rounf body) with black coil (this valve is being tested on some of the HFS-1 shipped since April/May this year).

That is all.