HX35, exhaust, and injectors?

[THEFERMANATOR]

You will get a tiny bit more fuel at a lower pop pressure due to less bleed off through the internal transfer ports and around the plungers, but not alot. Also lower pop pressure will give you slightly advanced timing. Fuel doesn't compress, but it does take time, encounter resistance, and has weight behind it as it travels through the line from the pump. This is why even though you set the injectors at say 2200 pop pressure, you can still easily see 11,000 PSI at the pump while the injector itself will rarely see more than 3500 or so.

 

[littleboy]

Lower pop pressure doesn't atomize the fuel as well. It tends to prolong the injection event and not burn as complete usually making more smoke ...

 

[restoguy]

I'm just a dumb redneck, but to my line of thought, if you take $1 out of your right pocket and put it in the left you won't find $1.05 in there.

If the pump is capable of 10,000+psi and it meters 50cc to an injector that has a pop pressure of 2200, then 50cc is what will be dispensed. If the pop pressure is lower the result is the same, 50cc. If the pressure was to change between injection events from 2200 to 1600 then it would meter just slightly more, but only for that one cycle. The variable here could be the return portion of the injector bleeding fuel during the injection event.

 

[THEFERMANATOR]

Lower pop pressure doesn't atomize the fuel as well. It tends to prolong the injection event and not burn as complete usually making more smoke ...

Yep, lower pop pressure gives less atomization as you need the pressure to get the fuel to turn into a mist instead of droplets.

I'm just a dumb redneck, but to my line of thought, if you take $1 out of your right pocket and put it in the left you won't find $1.05 in there.

If the pump is capable of 10,000+psi and it meters 50cc to an injector that has a pop pressure of 2200, then 50cc is what will be dispensed. If the pop pressure is lower the result is the same, 50cc. If the pressure was to change between injection events from 2200 to 1600 then it would meter just slightly more, but only for that one cycle. The variable here could be the return portion of the injector bleeding fuel during the injection event.

Not always. Even though fuel isn't compressible, there is places for it to bleed off under high pressure. Around the pistons in the poumps is sealing rings sort of like in a cylinder, and also you have bleed and transfer ports inside of the pump. Plus when you raise pressure, you essentially lose volume. Sort of like how if you take say a HOLEY blue electric fuel pump. It can free flow 140GPH at 0 PSI, but at 7 it only flows about 100-110, and at 14 it barely flows 60. The higher the pressure, the more places fuel will find to bleed off. Also this is where injector orrifice sizing comes into play. You can run higher pop pressure and get more flow but upping the orifice size, but this comes with other drawbacks. Theres no free lunch per say, but if the system is sized properly it can work quite effectively.

 

[restoguy]

But is the Holley blue pump positive displacement with no pressure relief? Granted there is likely some bleed off in the injection pump from internal leakage, but unless the pump is worn, that amount is negligable. And the difference in bleed off between 1500psi pop and 2500psi would be almost un-measurable. Especially when you consider that the pump is creating much more pressure than the injector pops at anyway. I would guess that peak pump pressure is almost the same with either pop pressure.

If I put my grease gun on a frozen zerk and squeeze, nothing happens. Because it's positive displacement and has no relief system. If the handle moves, it dispensed grease. But I don't get more or less grease depending on how hard I squeeze. It's always the same.

 

[ak diesel driver]

I think that in order to ensure the injs get the proper amount there has to be some residual fuel in ramping up and down in the pumping action. and also why you need a return line system otherwise everything would be going to the injs and no need for a return line

 

[restoguy]

My research on the interwebs has suggested that some fuel is allowed to leak through the injector to lubricate and cool it. So a lower pop pressure could result in more fuel entering the cylinder and less "leakage" getting bypassed. But I would reckon that the amount leaking to the return would be nearly the same at the pressures we're talking about. There might be a noticeable difference between 500psi and 5000psi, but I hardly think that 1700 leaks measureably less than 2200. I don't know for sure, but the amount allowed to 'leak' may be a specific amount built into the injector that never changes regardless of engine speed, injection pressure, etc. The info I found was pretty basic and didn't specify exactly how it was done.

 

[ak diesel driver]

there is a member on here who claims that his 1600 psi injs give him more power in his drag truck and 300 hp (not necessarily all from lower pop presssures)

 

[dka99burb]

Is the HX35 a good upgrade?

I was just doing some reading and found some comments stating that the HX35 is not much better than the GM8. Anyone have comments on this?

 

[Slim Shady]

I was just doing some reading and found some comments stating that the HX35 is not much better than the GM8. Anyone have comments on this?

The HX 35 is not much better than the gm 8, You would be better with a turbo that can grow with your needs. There are trade offs on every modification, fuel mileage would be a number one concern. I like my A team Turbo 1 to 3 mpg more on my rig and a few others. Just my 2 cents worth.

 

[Jorge6.5]

The HX35 would be a good upgrade if you got one with a 14cm2 exhaust housing. The 12cm2 housing is kinda small.

 

[dka99burb]

I will have to measure the housing. Mine was free so I would like to use it if it will be a good upgrade.
Anybody have a link to show easiest way or what to measure on the housing?

 

[Jorge6.5]

The exhaust housing is marked down by the t3 flange. Just give it a good look over and you should find the numbers cast into it.

 

[handcannon]

The exhaust housing is marked down by the t3 flange. Just give it a good look over and you should find the numbers cast into it.

Can you give me some hint as to where I might find this marking, and what it would look like? I have an HX35 already installed and am curious as to what one I got.

So far, I'm not overly impressed with it, but I'm still running the stock tune, due to lack of funds. My EGTs seem to have gone up some. The MPG doesn't seem to have changed any. My low end response hasn't changed much, mostly in a more sensitive go pedal.

Don

 

[turbovanman]

Any updates?

 

[Jorge6.5]

He never put the turbo on and now has his burb up for sale

 

[turbovanman]

He never put the turbo on and now has his burb up for sale

Bummer, what about Handcannon?

 

[Twisted Steel Performance]

there is a member on here who claims that his 1600 psi injs give him more power in his drag truck and 300 hp (not necessarily all from lower pop presssures)

John setup my IP & injectors, my IP is set at 95cc, injectors are set at 2100psi..... my timing is a little less advanced than some think might be best but with the built in advance with the gear drive, this motor is strong.

If I needed injectors reworked I would recommend Unique Diesel, John has done lots of testing and has proven his work.... and so far,,, he has had the largest dyno numbers for a 6.x that I have seen anyway...

 

[dka99burb]

I did the IP, injectors, exhaust, crossover, and didn't get to the turbo. Still running stock vac wastegate system. A tune and the turbo would be next. I guess that will be up to the next owner. We need a 4-door truck.

 

[dka99burb]

Well, I sold the burb today. But, he didn't get the goodies that I had not installed yet. If anyone is interested in a brand new FD, PMD, raceday HX install kit, or very lightly used FRC-10 let me know. It's been fun but I have to find a truck.