Stock Fuel Rails, why they don’t keep up

[Speedy!]

The alcohol pid is only active in a flex fuel tune.

 

[curt_dusterhofftuning]

I'm extremely skeptical that the rails are going to have a significant effect on fuel pump duty cycle. I will admit I have not tested before and after because we typically only do rails when doing a full return system. I wouldn't mind being proven wrong though. I would hate to recommend a mod to a customer I can't definitively say will fix their issue. I personally would add a bap and be done with it.

 

[curt_dusterhofftuning]

@yellow_hellcat - 71% inj DC wouldn't worry me with your inj pw and commanded EQ looking good. I'm surprised to see a pressure ratio of 2.25 and an aircharge of less than 1700mg though. What did that aircharge look like earlier in the pull? I'm assuming this is an E85 tune based on the timing advance.

I'd suggest adding actual fuel pressure to the log, that way you can compare commanded to actual.

Finally, fuel pressure can be increased a bit in the tune to a little over 90psi at WOT. Curt I'm sure knows how to set that up, pretty easy.

The concern isn't injector duty cylce, its pump duty cycle. It's never advisable to run the pumps at their max, fca wouldn't do it and I certainly don't advise a customer to do it. Given good da and a sustained pull, the issue will only become worse.

There's no way to increase fuel pressure when the pump is already maxed, not that we need to, the injectors aren't maxed. The concern is the pump being maxed.

 

[curt_dusterhofftuning]

I have a 55 gallon drum of E98, it tests 99.5%. I mixed E77 and E98 this morning to a electronically digitally tested mix of 86.5%, that’s what was in the car for today’s test on reduced timing settings. The car sensed it as 83.5%, it probably didn’t help with the fuel system keeping up today in 26F -1700 DA
Here a picture of the WOT alcohol spark table running today. Reduce more?
View attachment 34608

Who tuned your vehicle?

 

[16GoManGoHC2]

Who tuned your vehicle?

Sent you a Private Message

 

[curt_dusterhofftuning]

Sent you a Private Message

Thanks man. I'm curious about the rail mod and how it effects pump duty cycle ultimately.

 

[fubar569]

I'm also staying tuned.

I'm on the ragged edge of big money as-is. Fuel system included.

Something something full send blah blah.

 

[16GoManGoHC2]

Thanks man. I'm curious about the rail mod and how it effects pump duty cycle ultimately.

I still need to look for similar restrictions as found at the rail connections back in the pump area where the fuel line starts. I’ll be doing such in the next few weeks. In that last log posted my pump DC actually was not maxed at 89% for all of the top end of third and fourth like it was before the rails where opened up. I’m Working on my SuperCharger snout replacing bearings and opening the inlet up to 100mm to match the BBK TB to see what it nets. I tried it before in place of the Fastman 95 and it didn’t net anything, the stock snout inlet is 95mm so that may have negated the bigger TB. A ceramic balled hybrid bearing did not last long at all on the front of the snout, I’ll be using a high grade total 52100 steel SKF bearing this time. The balls where all pitted in the front 6204 bearing, the 6203 back at the coupling was fine, they’ll both be SKF this time. This hopefully was my knock issue. I also found SC heat exchanger had a slight leak right over # 2 cylinder, see the purple spots on #2 intake port in picture? Replacing both HX’s with spares I have. The SC was spotless inside, UPR catch cans are GREAT!!

 

[Hickster]

I had my stock rails replaced 3 times before 2,000 miles.

 

[16GoManGoHC2]

@Speedy! Think this could have been the source of knock?

 

[curt_dusterhofftuning]

I had my stock rails replaced 3 times before 2,000 miles.

A lot of times that is due to frp failure as there really isn't anything in the rails themselves to fail

 

[curt_dusterhofftuning]

@Speedy! Think this could have been the source of knock?

Lol ya I think the knock sensors might pick that up

 

[16GoManGoHC2]

Lol ya I think the knock sensors might pick that up

They are set up stock yet and very sensitive, I’m hoping that’s what was triggering them. While off and apart I opened up the inlet to match the BBK 100mm TB that’s going to be the next addition. It’s a hair under 100mm as I wanted to retain the factory oring groove but with the BBK attached it’s a near perfect smooth transition from T to snout.

 

[2fast4u]

Your work looks fantastic, must have a steady hand...LOL

 

[16GoManGoHC2]

Your work looks fantastic, must have a steady hand...LOL

THANK YOU!! Unfortunately I shake like I have Parkinson’s but having the proper burrs and sanding drums does wonders at covering it up LOL. Only took about 2 hours start to clean up. Plus I grew up with the only way I could afford porting, port matching, etc was doing it myself lol. Aluminum is easy, old cast iron heads now that was a task!!

 

[Hickster]

That is some nice work. I used to port and polish street choppers and it is time consuming and a 12 pack for a steady hand. Looks great. Hickster is still kicking. No moe 45 over speed limit tickets,, yet. But have not seen the judge. He can fine me all he wants but my Gastro test comes back positive in 2 weeks for cancer. Well, he can beat up my estate fer it. B- Day tomorrow for apple pie shine. Weather down here is mid 70s. Perfect. Engine work looks great.

 

[Mean Cat]

They are set up stock yet and very sensitive, I’m hoping that’s what was triggering them. While off and apart I opened up the inlet to match the BBK 100mm TB that’s going to be the next addition. It’s a hair under 100mm as I wanted to retain the factory oring groove but with the BBK attached it’s a near perfect smooth transition from T to snout. View attachment 36443 View attachment 36444 View attachment 36445

Good job but Man that's a thin lip, I hope it still seals good ?

 

[16GoManGoHC2]

Good job but Man that's a thin lip, I hope it still seals good ?

It seals on a oring that goes in the groove, the thin lip just keeps it in place, it’ll seal perfectly like this. I’ll post a picture later with the seal ring in place and you’ll get the idea what leaving the thin ring does.

 

[16GoManGoHC2]

Good job but Man that's a thin lip, I hope it still seals good ?

Here is the intake end with oring gasket installed (green thing). The only aluminum face that does any sealing is the one in the bottom of the groove, the sides just capture the oring and keep it in place, then the other face of the oring seals against the back side of the throttle body. If the groove is machined out such as done to open it up for a 105, 110, 112 mm TB then this whole groove is machined out and a traditional flat paper type gasket is then used for a seal on the outer flat aluminum surface, not ideal as it does get very thin when that’s done especially when you go to 110,112 mm it’s about gone.

 

[Mean Cat]

Here is the intake end with oring gasket installed (green thing). The only aluminum face that does any sealing is the one in the bottom of the groove, the sides just capture the oring and keep it in place, then the other face of the oring seals against the back side of the throttle body. If the groove is machined out such as done to open it up for a 105, 110, 112 mm TB then this whole groove is machined out and a traditional flat paper type gasket is then used for a seal on the outer flat aluminum surface, not ideal as it does get very thin when that’s done especially when you go to 110,112 mm it’s about gone.

View attachment 36474 View attachment 36475 View attachment 36476

Yeah, I thought there was just enough lip left for the O-ring but it looks like if you go any more it will suck that O-ring in.