I own a Perrin PWI-1 system. It has a version of Aquamist's race pump in it. The system is very nice and compact.

For my application it didn't quite flow enough, so I bought the HFS-5 system.

I have since learned a few things:

Going from 400ish ml/min (with primer pump) to 550 or 600 made a noticeable difference in tuning. Not huge, but allowed an extra degree of timing, and leaning AFRs by 0.2. I also learned (common sense I guess) that running more alky means the motor is more susceptible to changes in the alky mixture. When I first had the Perrin system I was only injecting about 250 ml/min and didnt notice much difference from WWF to my own 50/50 mix. Now the difference is huge!

The thing that I found very interesting was that the little race pump seemed to have very very linear and controlled flow. (I had a DDS3, gauge only, installed with it) Now the HFS-5 has very good flow control vs the competitors because of the HSV. But compared to the race pump it just doesn't seem to have the control.

This is all just my observations from a few months of driving and self tuning watching the DDS3 gauge.

Anybody else notice this?

 

There is a subtle difference between the systems. The Perrin system commences from 0%DC to 100% DC compared to the HFS5, starts for a specific IDC point, It could be anywhere between 12% to 72%.

Try lowering your triggering point to 12% - it won't flood your car. At idle the duty cycle is about 1%. Also matching your jet with the restrictor pill is important.

The Perrin system is by far the most advanced system on performance and fails safe algorithm to date; full time error tracking is standard. The pump is mapped with PWM and PPM (pulse position modulation) to follow a design delivery curve to match the flow against manifold pressure.

It doesn't have the "low flow" (low pump speed) = "low atomisation" (low pressure) symptom associate with the normal PPS system based on a rotating electric motor. There are on "inertia" delay or "run-on" dribble after switch off.

It is compact, neat and has all the necessary functions... and it is the most under-rated system too. If you are not looking for monster power, this is the system to consider. Price is not very competitive since Perrin has dropped one tier closer to the retail user.

Thanks for your fair comment on the Perrin system.

 

My HFS-5 system has the medium sized restrictor with two 0.6mm jets. Appropriately sized IMO.

The HFS-5 system will spike a bit on start-up (based on flow as shown by DDS-3) and then settle. The Perrin system is just dead-on accurate.

I also understand how the Perrin failsafes are better. If you are at 50% IDC and system maxes out at 80% IDC the low/over flow will function better.

 

Try the smallest restrictor and let me know if it improves. It is possible to drill out the restrictor to match your x2 0.6mm jets exactly.

The characteristics of the HSV is almost exact match as the fuel injectors. If the HSV maxed out, it is probably a reflection of the fuel injectors.

 

Is not the smallest restrictor for 400 cc/min or something like that? Won't it flow too little then?

What size should I drill it out to to match the flow of two 0.6 mm jets going into a 21 psi pressurized intake manifold.

My IDCs are right around 90%. I don't understand exactly what you are getting at with IDC.

 

A 400cc restrictor doesn't stop flowing water when it reaches 400cc/min, it just slow down the rate of flow. It wont take too much work to change it. Worth trying. I think you can also set the HFS-5 to come on earlier. There just isn't that much of a span.

Try to turn the triggering point down to 12% - you don't need to retune as the Perrin system because it mirrors the %DC 1:1.

 

I will try the 400 cc/min restrictor. At least as long as the DDS3 stays calibrated on the same spot I will see the flow difference.

It is funny that you write about turning down the IDC starting point. I don't think I even posted it.

My IDCs max out at 90%. I start injecting at around 30% IDC or so, which equates to around 7 psi (depending on gear and load, etc...)


I don't want to start injecting any earlier then that.

 

I forgot, about the failsafe - also looking for flow data earlier.

 

Not sure I know what you mean by that last post Richard.

 

When you lower the trigger point, the fail safe window will go wider. Which mean that you need to adjust "WL". Make a record of clicks before adjustment.

 

Yea, that is easy.

Why again should I lower the trigger point? I think it is pretty low already.

 

Just to test the linearity, so it appears to work closer to the Perrin range. Not a permanent setting.

 

I see now.