So had my local guy completely weld them on the outside and then ran them by machine shop who had a large belt sander to flatten the flanges
first pic is the stitch from ARH, they are (or were) fully welded on the inside, following pics are after local welding

 

Fuel system,
I want to run flex fuel and have the ability to run full e85, not mess with meth, not spend 5k on DI parts and immediately have to swap cam in. not to say cam is never goin to happen, just not right now. so decided to go with port injection - DSX port plates, gm 50lb injectors (very well documented injector data) between the DI and 50lb PI injectors, should be plenty to flow 900hp+ on ethanol.
needing intank pumps to feed all those injectors, i went with the Katech drop it dual pump module, retains the bucket, venturi, and the primary pump is able to be controlled by the stock fpcm. for the second pump i am using a vaporworx LT4 controller, it mimics the fpcm pwm signal and drives the second pump with it. the fpcm doesnt really know its there it just thinks whatever pump its connected to flows "twice" as much.

heres where the first major struggles began lol
so no real issue installing the module, pretty much like stock its physically larger/bulkier than the stock module but it all still fits in the tank. it requires an external fuel filter, so i end up buying parts/material to swap it over to 8an from the tank to the front,, split between DI rail and PI rails, install the flex fuel sensor, and everything just to get it out of the way. this is really the only difference between what everyone else has done vs what i did. but was assured the stock line would flow 1000hp+ but i had to redo it all anyway

started tuning and pressure would still drop off under decent wot load. recheck everything outside the tank, no real reason why it should - other using same in tank set up report 80psi all day pushing way more hp than my few bolt ons. so maybe cracked hose, loose clamp whatever. decide to drop the tank and check everything again(pay to have shop do it). nothing obviously wrong, check all connections, hoses. put it back in. seems somewhat better. i start running it thru different scenarios full tank/half tank/empty tank. it acts like its sucking the bucket dry (worse when tank below half) so i buy new venturi lines and module, in the event one of those is broken elsewhere in tank, have the shop drop the tank again, check everything again, i stop by and look it all over myself - not that i dont necessarily trust them but i want to see for myself. bench test each pump.... seeing nothing, i told them throw new venturi line and module in and put it back in.
wasnt any better, with a full tank pressure would drop from like 78psi commanded down to 60psi. below half tank it would drop into the 30s. After testing out a few more things, i was fairly convinced there was something wrong with the module. in the back of my head there was always the "going from 6an to 8an shouldnt matter but maybe some weird fluid dynamics was happening". so instead of going back down to 6an i grabbed what i needed to gut the bucket and put it an 8an bulkhead and just run 8an from the pumps. I eventually dropped the tank myself in my driveway, pulled the module, threw it in a 5gal bucket with enough fluid to submerge the module and hotwired a pump - everything looked normal, but i noticed down in the pump module itself there was fluid swirling. so i dead headed the pump, still swirling like inside the module itself.
this in tank pump uses ,what im going to call, a little manifold to join both pumps, the discharge, and an oem pressure relief - not really a regulator its set at like 90psi just to prevent dead heading the pump. well the tube that went from the manifold for the pressure relief goes thru the top of the module, thru a "stand" down to the housing of the pressure relief valve. where the stand meets the housing it was just blowing fluid out there, like there was supposed to be some sort of seal/grommet/orings. at that point i had it all apart, i had all the parts i needed to gut the shit, so that what i did and just deleted the pressure relief valve.
Until i could get the fuel pumps figured out there wasnt much point it doing anything more.
also to add, it would not hold any pressure priming while starting, added checkvalves that helped some, but still would stumble a little starting. i came across reading somewhere that you could approximate the pwm signal by measuring the volts across the circuit. ie 7v on 14v =50% duty cycle... well i was reading almost 10v just trying to maintain 50psi at idle. which worked out to like 70% duty cycle so knowing i had to be blowing fuel out somewhere and it obviously wasnt outside the tank it had to be inside. finally led me to just pull it and either find out what was wrong or make it work for sure.

 

ended up with something like this in the tank

getting off of the tank with 1/2 wasnt so easy, i tried to follow the factory routing but it wasnt going to happen, not without also having to splice in the fitting for/and the pressure sensor.
so quickest way off the tank it was. its away from the positive terminal higher than it, i also threw a little rubber nub on there to insulate it in the event it did somehow make its way to it.

 

Sooo, after all that mess. the first time i hit the key and watch the scanner, thing made and held 110psi. not sure if swapping to the c7 pressure sensor was skewing the reading at the time but it also showed as roughly the same on the high pressure rail, so i was fairly certain it was reading correctly. and now it holds commanded psi no problem - more mods!
in between all that, deciding to do port injection and having to pull the blower anyway, i had them throw on a griptec hub and 2.30 pulley. so the 17% lower is way too much to go with it.
we (tuner) pretty much said i could run probably like E50 as it sat, if i threw on lower it may not be able to run any ethanol, but i wanted to get the parts on it even if i cant drive it to its full potential for a little bit.
a few of the other things i wasnt all that enthused about how they were installed.
i grabbed the DMS CWA pump and harness, LMP bumper tank. shop installed the pump where the stock one is, very tight, you could see where the belt was barely rubbing away at it. hoses had to both run to in front of the core support, seemed dumb. so i moved the pump out to in front of the driverside, shortened hoses.

DSX SC lid... i liked how much it cleaned up under the hood, but loathed the wiring harness and vacuum lines that still ran across it. i was able to tuck the harness under the supercharger since the port plates brought it up. i re routed the driverside valve cover vacuum line, the fuel purge solenoid, and the vac to intake hose.

 

all the hardware was also miss matched, some studs not needed anymore, etc... I tried to use some different water manifold adapters, but with the port plates/90° an fittings the hood doesnt close. 12an anyway...10an may have worked but just trying to get it back together and working at this point. heres about where im at with it:

 

few more random pics...

 

Digging the build my man.

 

thanks man,
making any headway on yours?

 

Yeah, just posted another update. Getting the injector done. All the other crap was speculative bullshit.

 

Btw, $2k+ for headers with bullshit welds and warped flanges is horseshit. You’re a better man than me…I’d have returned that shit…but I get the time value of money.

Based upon that level of craftsmanship, did you shine a light down the tubes/collector to check for pinholes?

 

Btw, $2k+ for headers with bullshit welds and warped flanges is horseshit. You’re a better man than me…I’d have returned that shit…but I get the time value of money.

Based upon that level of craftsmanship, did you shine a light down the tubes/collector to check for pinholes?

i hear ya, i just had mulled over so many setups, mid pipes, tube size, mufflers, resonators, cats, etc....and had decided on what i wanted. and didnt feel like starting that whole process over again.
at the same time, the car had been sitting at a friends shop taking up a lift for a couple months, so ordering new or waiting for them to be fixed wouldve started pissing him off
the fix was easy enough, but yea for the price it was disappointing

 

Subbing. I enjoy build threads.

 

Subbed. I also got the Katech Dual Pump and had zero issues for about a month but started not to hold pressure after a Drag day and hot weather.

I'm wondering if the "seal" in that manifold connection got undone with mine too.

 

i dont think mine was ever right - so it was hard to diagnose without having any reference how it was supposed to work.
i replaced the fuel line from the tank forward initially, changed it to -8an, and then split it up between the DI and PI rails. I unknowingly removed the check valve in the flex section, so we put one back on the DI line which helped some but would still stumble a little on startup pretty often.
the first issue that came up was it wouldnt hold pressure priming. it would crank over for a while and sometimes not even start. scanner would show zero psi on low side - second time id hit the key it would start immediately. now that i know how its supposed to work that would have been a dead give away.
while doing pulls it would meet the commanded pressure targets but as soon as i laid into it, it acted like it was out of pump (low side pressure drop and in turn high side).

high side is about tapped out at this point, can run about E30 mix but high side starts to fall off and is not happy right at the hit. still holding out for DSX port controller, rails/injectors/plumbing is already installed. getting it on full e85 should pickup a nice bit, only other bolt on that will likely get done in the immediate future is ported blower/103mm tb.

 

I like your build. I see a lot in common with the way mine goes, and your writing style is similar. I'll be following.

 

seems to always be the way it goes! i guess my expectations were too high having someone else do the work
i also dislike not knowing how things are done whether it be trying to troubleshoot something or when i work on stuff myself i generally try and eliminate any obvious problems and at least make a mental note of what could go wrong if i do something im not proud of.

 

Any updates on how you like the LMP front bumper HX tank? Thinking of pulling the trigger as I have the smaller Cordes one.

 

No complaints so far, but not sure it'd be worth swapping from one to the other.
I had them fab it with a smaller fill cap (wasnt ever planning on using ice) cap isn't tiny if i really wanted to ice it wouldn't be too hard. And at the time I was gung-ho with insane cooling-cwa400/16an lines. So I had them weld an bungs on instead of the hose barbs. Ended up using the dms cwa150 and 12an hoses. LMP still had it from order to shipped within like a week, including powdercoat.
Would start with pump/hoses if you haven't already before swapping the tanks

 

No complaints so far, but not sure it'd be worth swapping from one to the other.
I had them fab it with a smaller fill cap (wasnt ever planning on using ice) cap isn't tiny if i really wanted to ice it wouldn't be too hard. And at the time I was gung-ho with insane cooling-cwa400/16an lines. So I had them weld an bungs on instead of the hose barbs. Ended up using the dms cwa150 and 12an hoses. LMP still had it from order to shipped within like a week, including powdercoat.
Would start with pump/hoses if you haven't already before swapping the tanks

Thanks for the update! I did get a CWA 150 so I'll do that first and go from there. Solid build you have.

 

New year update...
Had another issue with the in-tank pumps, symptom- wouldnt maintain fuel pressure again, even worse this time. diagnosed everything i could without dropping tank again but no luck. At this point kind of conceded defeat and external aux pump wouldve been much less drama, if i could leave it alone when aux pump max'd out anyway. so tank had to come back down.
problem this time, was the hose that makes a 180° to the primary pump. the hose was too long (my fault i guess) when you stuff this monstrosity back into the tank the hose was actually sitting against the top of the tank (its offset from the fuel hat). hose didnt rub through or anything, i think it was just smushed in there and ended up splitting the hose. I had a hell of a time getting these corrugated hoses on the first time so i ended up replacing both of the hoses while it was out(shorter hose between these two), re-crimping them. has been fine since.

one other seemingly random issue is my car makes a lazy 4>5 shift. part of it is the larger gap in gearing after 1-4 shifts, but also in the logs shows shift times .7+. so one morning i was just cruising not even really beating on it and went to pass on the highway and it sort of acted like it popped out gear the way an old shitty manual would and rev'd to redline, CEL, then just wouldnt make any 5,6,7 shifts. i didnt have anything to check/clear codes with me, middle of rush hour morning traffic. it would make first couple shifts and get up to like 50-60mph and then you could feather it into 8th and lockup and cruise ok-ish. so i limped it home. i just jumped in my truck and went to work, didnt have time to mess with it. sat for a week or two... i was fairly certain it just wiped all those steels clean. in that time i started looking to see what rebuild/replace was going to cost, 10l90 swap maybe (still a maybe). got around to actually diagnosing. made sure fluid level was good, had a bunch of codes but they were all for like tpms and wheel speed sensors, loss of communication with some module basically threw the trans into limp mode cause it wasnt getting speed signal 🤦‍♂️. i checked over all the harnesses, connectors, harnesses around the headers, inside the wheel wells. couldnt find anything so just rare fluke occurrence at this point i guess. cleared the codes, still makes same sloppy 4>5 shift

next immediate mod:
DSX port controller and dual wideband set up has been ordered (the port rails, plumbing, and injectors have been installed for a few months now).
was going to just order the controller and tune it off the wideband i already have same way it would normally. however, with the additional dual widebands, the controller will provide closed loop fueling 100% of the time via the port injection and will also compensate for bank to bank inconsistencies independent of each other. much of tune needs to be gone back through, rail pressure on the high side wasnt just dropping in high rpm, some wot launch/downshifts got lightened up. so hopefully can feed some power back in those areas.

for those not quite on the mod path yet... while i would say the port injection does have more potential - with what ive now spent on plates/injectors now controller and widebands, going thpsi wouldve been a little bit cheaper. part for part i would be in it around the same cost as a cam/30% injectors. labor if i was paying someone to do it would be more but the setup wouldve been simpler.

 

Were you using the Katech Dual-Pump? I was having issues with that pump as well and just switched over to the DSX dual pump, which seems more robust and I have also heard great things about it. I am also planning on going the DSX port direction as I now have +30% XDI and Lingenfilter HPFP.

 

Yea, still using the katech drop in (DW400s). When i went looking, Katech was the only option. I picked up the vaporworx controller before katech started providing it as a package - I do like how simple of a solution it is to control the second pump. between the pumps and controller the price is pretty much the same as DSXs which comes pumps and controller all together
i think i read DSX uses twin hellcat pumps?? they should be able to provide more fuel and imo be more reliable. not sure what he's doing to control the second pump but i believe its also pwm controlled?
i havent really had problems with the DW400 pumps themselves, its just been the plumbing mostly. which looking at the DSX theres a billet block that the pump discharge connects to and then out of the hat. that is nice and solves a lot of problems. the fixes for this pump setup have been cheap, its removing the tank to do them that is getting old quick

 

Someone just sent me this thread.

Please reach out to me if you have a Katech module that will not hold pressure.

mike@katechengines.com

 

feel like a dsx fanboy at this point, but the parts are nice.
fuel module, twin walbro ti295 pumps 535lph(?) each. billet bucket, billet hat, billet manifold, retains venturi function, has an 8an port for return thats blocked off if thats how you want to run it
kit comes with second fpcm, complete wiring harness to integrate, .htt file to change all the tables that need changed in the tune, the 2pin connector in the pics below is just for the level sensor, just depin the oem connector and pin the one they provide
the unit itself is still very bulky, without the flexible hoses it seems easier to install however - could just be that ive taking it out and put it in a handful of times now.
i did want it with an -8an on the hat, but the tube inside the tank is also only 3/8 so from a flow perspective wouldnt have made much difference
these pumps have no internal checkvalve so they need to both be ran full blast with return or both by pwm and the second fpcm.
i did install the lingenfelter high flow check valve - Direct Injection High Flow Check Valve Assembly under the car. not sure if i would have any priming/starting issues but i've had it sitting around for a couple months and was waiting for parts to show up anyway.
noticed one of the rear o2 bungs had a bit of soot around the base (where the widebands are currently) like it just didnt penetrate the tubing. so i wirebrushed/cleaned the hell out of it inside and out and ran tig welder over it with a little more filler to hopefully seal it up.
had a couple of broken bolts for some of the undercarriage plates, i was able to just drill and extract them and replace with some new hardware.
the clips for the plastic fuel/vent hoses, i lost one completely somehow and had another that broke one side off of it so it barely worked. i dont think GM sells us the clip so you have to buy the entire hose. plowed thru abunch of google pics and took a chance ordering some dorman plastic hose ends that had what looked like the correct clip and got lucky with these for the 3/8 vent tube that runs over the tank (and should also fit the oem fuel line from the tank if needed)the red clip: Amazon.com

 

not much of an update but need some motivation/accountability
after swapping in the new dual bucket, immediately went on a little road trip about 500mi round trip. filled up with 93oct to get a little more mpg out of it everything seemed to run fine but felt down on power, assuming it was just because i had been running it almost only on straight E85 and that little lack of timing wasnt really as bad as it felt to me. BUT on the return trip home I did a quick data log... fuel pressure was dropping to crap, like only a single pump running kind of pressure. sort of luckily, i guess, i was on 93oct and not e85, or it would have really of taxed a single pump. not sure if it just didnt like running for hours on end or what, checked everything over, rechecked all connections, tested out pumps, it hasnt happened since (few months) but still is a concern. having an issue now where every once in a while it wants to just run 72psi all the time and not ramp down to the commanded at idle/low flow, so going to check it all over one more time and try and figure that out.

im not a fan of gauges but wanted something i could easily watch with having to data log or use a bluetooth app to monitor stuff. sooo went ahead and added P3 vent gauge, it doesnt have anything native to watch fuel pressure, so i had to use one of the analog configurable inputs to another fuel pressure sensor i added to the end of a port injection rail.
the other analog input (has two total) i am trying to get a temp sensor in the sc coolant reservoir to watch that temp. the gauge is looking for a 0-5v signal though and most temp sensors (gm anyway) are just a resistor style and not linear - i've tried a few sensors with a "fast" converter to 0-5v but getting it any kind of accurate across the range is way off. i think i found an "active" linear sensor that will work, went ahead and ordered it to try out.

sc coolant hoses.... have kind of bothered me running over the intake tube. when i had shop do it, it was probably the logical way to do it so i lived with it, till now anyway. started re routing them, knew kong had a new coolant manifold out that i wanted to use eventually. was just going to make the hoses and hope i could use them later but went ahead and ordered the manifold to just make the hoses once. i was able to route them slightly back, under the tube, and one along side/one under the rotofab "housing"

 

Pretty sure we got the fuel system sorted out. I reached out to DSX, as I had a wideband controller go out. Started talking about the fuel system, he mentioned a few people had similar issure where a retaining plate at the bottom would distort under high pressure. And cause pressure to fluctuate. So he updated the plate, made it out of stainless, added ribs to stiffen it. Also mentioned the venturi hose could cause the issue I was having. So he sent out the new plate and o2 controller and I ordered another set of venturi hoses since tank was coming out anyway. Dropped tank for the hundreth time, Got it all swapped out, pressure is a lot more stable
Also along the way, it was breaking up under wot, I had assumed it was fuel issues so I was trying to get that squared away. Logging misfires made it very apparent it was cyl 6 with a couple hundred. Tried the ol' new coil, sparkplug, and plug wire and it , surprisingly, cleared right up. plug wire just fail, created a little blister on the wire, like an inch from the coil no where near anything, not rubbing anything, far away from heat.

Really needed to get back to performance mods... but deal came up.
10l90/converter out of a 2021 zl1, not even 3200miles on it
Had a friend go scoop it up this morning.

 

Pretty sure we got the fuel system sorted out. I reached out to DSX, as I had a wideband controller go out. Started talking about the fuel system, he mentioned a few people had similar issure where a retaining plate at the bottom would distort under high pressure. And cause pressure to fluctuate. So he updated the plate, made it out of stainless, added ribs to stiffen it. Also mentioned the venturi hose could cause the issue I was having. So he sent out the new plate and o2 controller and I ordered another set of venturi hoses since tank was coming out anyway. Dropped tank for the hundreth time, Got it all swapped out, pressure is a lot more stable
Also along the way, it was breaking up under wot, I had assumed it was fuel issues so I was trying to get that squared away. Logging misfires made it very apparent it was cyl 6 with a couple hundred. Tried the ol' new coil, sparkplug, and plug wire and it , surprisingly, cleared right up. plug wire just fail, created a little blister on the wire, like an inch from the coil no where near anything, not rubbing anything, far away from heat.
View attachment 179593


Really needed to get back to performance mods... but deal came up.
10l90/converter out of a 2021 zl1, not even 3200miles on it
Had a friend go scoop it up this morning.
View attachment 179592

That's awesome that she's driving better now. I'm super eager to hear/see your results with the 10 speed. I was thinking of doing that very same mod.

 

I like the abuse

 

i was left unsupervised for too long over labor day weekend.

went ahead and swapped out the fuel pumps... kinked that chintzyass plastic fuel hose coming off the tank right where it reconnects. not sure if maybe someone had already done it before me cause i wasnt forcing it or anything. either way i barely trust it as it is so i ordered a new one - may try and change it over to an/hard line (again) but its just an awkward piece that includes the fuel pressure sensor and quick connects.
i rushed ordering the PSS swap kit because i heard they could take a few weeks to get the order out, ordered and delivered in like 3 days. the PnP nature of it i think it going to annoy me, mostly because it basically just leaves the 8sp connector wiring in the car. depending on how anxious i am to get it all back together i may strip it out of the harness after i make sure everything works
since i had the exhaust and driveshaft out anyway - i went ahead and started the 10speed swap. 8speed is like 98% ready to come out, only thing holding it in is the mount for it. my transmission jack is toast i havent used it in years so i had to order a new one i could prob get it out with a floor jack and not give a shit about it, but would still need to put in the 10l90. pulled the wiper cowl to get to the top bellhousing bolts....i may end up re doing some of the fuel distribution and a few things while its all open and accessible behind the supercharger, but that led to another distraction...
the mighty mouse catch can needs to blockoff the valley cover opening, so i pulled the supercharger (really just needs to be loosened and lifted up a few inches) but since i was there anyway i pulled it off completely. prob shoulve done catch can a long time ago, a little oily inside but not worst ive seen. getting sent out for kong xport and 103mm.

 

Nice build, man! i am wondering if you've had any hot start issues, as I developed one with similar mods with me running port injection on Atlas

 

this from a few posts up is about the extent of what i had problems with, not really a tuning issue my fuel pressure was just crap ~20-30psi at hot restart:

"I'll stop and grab breakfast or something. restart it 10 min later and everything goes to shit, fuel pressure acts like its only on one pump (and dumb on my part) i elected for pumps with no check valve. so if only ones working its pretty much blowing thru the other and i have 20-30psi of fp with the pump forcing 100% duty cycle. and intermittently the second pump comes on, pwm calling for 100% so then fuel pressure shoots up to 110psi, by the time fpcm corrects and brings pressure down second fpcm shuts down again and back to 20psi of pressure. rinse repeat."

I thought it may be because of the twin fpcm, one of them faulting or not communicating or something. i removed the second fpcm and put the vaporworx back in to control the second pump and the problem was "fixed" > ie no more hot start problems, BUT i noticed my fuel pump duty cycle way high just at idle and cruise (65%+) just to maintain ~50psi with zero engine load. WOT had great pressure, and i probably couldve left it for a while and been fine.
can only speculate at this time but im thinking the twin fpcm was probably fine and the pumps may have been the problem. going bad or sucked up some debris maybe - after running the pumps for a while (daily commute is hour+) exacerbated the issue. putting 12v on them now on the bench they "work" fine, you can move the impeller without much resistance, but im thinking the low PWM signal had a hard time getting them spinning.
pumps are now swapped, but wont know if its fixed till it gets put back together - aside from obviously providing sufficient fuel WOT, that would be seeing the duty cycle for the fuel pumps back down around 30% with little to no load to know that there arent any underlying problems

 

yep, fueling has definitely been the biggest pita building this thing. and it just wasnt consistent so i had to be ready to throw the scanner on it at all times.
in the interim, while i wait on parts, im probably going to take a look at external fuel filter media, i'll prob take the check valve apart off and make sure it looks like its working also maybe redo a few of the lines