Hyper4mance2k

iTrader: (40)

It's a S513BT blow through weber 45dcoe w/ a mallory 4307 FPR and Holley blue fuel pump incase you needed to know. So where should I hook up the boost reference port on the mallory FPR? It's on the intake manifold right now. Question is that if the turbo is building boost at say 3000 rpm cruise then how would the FPR know that there is boost on the carb side of the throttle plates if the FPR is seeing vaccume from the manifold. How would it know to increase fuel pressure to the carb and cruise no matter how big of a pump you have. I ask because I was kinda mad and just hooked up the charge pipe and it went brickwall lean when I was at part throttle, but if I just stomped on it, it would haul *** down the road at 5psi and the fuel pump was keeping up fine nice and rich . Oh and its scarry fast, but I can't drive it over 3k at any type of part throttle or it goes off the map lean and surges, but there is vaccume in the manifold. Do I just need to shut the fawk up eat more cheeseand buy a bigger fuel pump, or what? Again its currently a Holley Blue 14psi@110gph as opposed to the GSL-SE which does 50 psi @ 27gph.
I was thinking about hooking the reference port on the FPR to the wastegate line but the boost controler is a bleed off type so if I'm boosting 12 psi the FPR is only going to seee the 5psi the waste gate does, right?

REVHED

I'd definately put a bigger pump on for starters. An EFI type pump regulated down is the way to go.

I think with a blow-through you should reference it to before the carby. Maybe weld a fitting onto the carb hat?

Hyper4mance2k

iTrader: (40)

you think or for sure? Now I've gotten both answers. (pm)

inuissus_cendi

going on pure midnight logic I'd agree with right before the carb. The point of boost referencing it is to make sure your fuel comes at the carb with the same amount of pressure greater than the pressure of the air inside the carb. So fuel pressure - boost = whatever fuel pressure your carb requires.

So yeah the best place to reference it is as close as possible right before the carb, because thats where the boost matters in this case.

My 2 cents

Hyper4mance2k

iTrader: (40)

Cool thanks I just hope one of the 300 blowthrough 1st gen owners posts...

Directfreak

iTrader: (2)

When I ran the Holley, my boost reference line was on the Carb Hat.

Hyper4mance2k

iTrader: (40)

Cool thanks!!! Your my hero by the way. Thanks so much!

Sudox_E

Mine is before the carb hat also. As far as your fuel pump, I had a 16psi, 150gph aeromotive fuel pump, and it wasnt cutting it. The thing is, I thought that 16psi of fuel is all I would possibly need, running 10lbs of boost (so that's 6psi base fuel pressure + 1psi for every extra lb of boost). But When I was on the highway in 4th or 5th doing a hard pull, my car would stutter, lose power, etc... I looked at a flow chart of my pump, and it flows 16psi alright, but at 1 gph! I just ordered a Walbro high-pressure 255lph fuel pump, and I expect it to do fine for me. Ditch that holley and get a good efi pump

Hyper4mance2k

iTrader: (40)

I will for sure the walbro is in my next paycheck future. I just wanted to get it running at 5psi. and the Holley should do that right now. Does anyone webered have a pic of where exactly it's tapped. Should I just get a fitting at homodepot and drill and tap a hole in the carb hat?

680RWHP12A

[QUOTE=Hyper4mance2k]I will for sure the walbro is in my next paycheck future. I just wanted to get it running at 5psi. and the Holley should do that right now. QUOTE]


nope , wrong.. ive said it many times , for blowthrough applications you need an EFI FUEL PUMP!!!
now go buy a walbro and eat sum cheese till it shows up!

Hyper4mance2k

iTrader: (40)

Wakka wakka I tapped the charge pipe for the reference for the FPR and it fuggin runs great! I Love Boost!! I don't know how long I lived without it! only going to run 5psi until I get the walbro. This might not work for everyone make sure you've got a good BOV if you're going to run it this way. I've got a greddy so it works.

680RWHP12A

bov will make all the difference when running the fpr tapped in before the throttle plate

the carb hat will have a higher boost refrence than after the carb(the carb is a restriction), so you will get more fuel pressure..
so was all the work worth the boosted feeling? you almost gave up a few times !

Hyper4mance2k

iTrader: (40)

Hell yea it was!!! I did almost give up! I guess Greg told you I tried to sell it huh? LOL!! I'm happy I stuck with it! I'm going to eat 10 casadillas and dedicate them to you.
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680RWHP12A

yup, greg told me, im glad you didnt give up.. im also glad i was able to help, as well as others on this forum
rotary power, no pistons, no problems

Hyper4mance2k

iTrader: (40)

Is there anyone who has successfully set up a weber blowthrough that was good enough to autocross with? From what I'm hearing here people are only drag racing with them. Well what it's doing now is that anytime it's part throttle and there is between 10lbs of vaccume and 0 in the manifold it goes lean clear off of the gague. It's really scary if you ask me. I just built this engine, and thing last thing I want is it to detonate.

mr_ouija

Running lean out of boost shouldn't be a problem, so long as it fattens back up when you hit the boost. Also, are you running a wideband? If not, the narrowband sensors lack accuracy anywhere but a small range useful for N/A. On my FD w/ a narrowband hooked up to a AFR gauge, it would jump from all the way rich to all the way lean pretty often. Under boost, it stayed rich though. I disconnected and sold it a long time ago because of it's lack of usefulness. I've got a wideband now, just been too busy working on the FB to install it.

REVHED

You trying to tune this thing with a narrowband?

One thing I noticed when tuning my car with the Microtech wideband was, if the mixture got really fat it would actually make it read lean because the o2 sensor gets saturated with fuel. Something to keep in mind.

Sudox_E

I need to get a wideband also, but theyre pretty expensive. I need to find a friend who can let me borrow his, but that would takea pretty good friend I'm having similar issues with my narrowband, it often goes all the way lean for a split second, and I can NEVER get it to read stoich at idle or while cruising, even when I know it's not getting hardly any fuel. Also seems like it's running too rich under boost. Sounds like its time to drop some cash on a wideband.

85TIIDEVIL

iTrader: (2)

So wtf is the purpose of a narrowband / air fuel meter..? Besides the light show...?

Sudox_E

I've read up on it a little bit. Apparently it's accurate within a very narrow range, as if that wasnt obvious (NARROW band as oppossed to WIDE band). I don't know why mine never reads stoich, but it has let me know when my car ran lean under boost (fuel pump problems), And if I'm running crazy rich, it will read all the way rich on the guage. So I guess for my purposes, which is accurate tuning for a turbo car, theyre not very good, but I know that on efi cars they serve some purpose, providing the ecu. haha, I should know, but I don't know **** about EFI! That's why I'm sticking with a carb for now..

85TIIDEVIL

iTrader: (2)

It definatly works for me... When I am in top of fourth gear at WOT the car breaks up and sputters, lack of more power... The AFM dips deep into the red / lean area. It hasn't concerned me to attend to the cause yet because I rarely drive above those speeds anyways. It stays in a nice orange-red / stoich-rich area under cruise. I'm in the process of switching everything over to a new body and I'm deciding if I should even bring it over to the new car... ???

Hyper4mance2k

iTrader: (40)

Okay I know I need a wideband, gee thanks. but it goes clear off of the map lean and takes a second or two to catch back up and it surges from it being lean. Thank god not under boost when it does it. And it's jetted right. Without the charge pipe it drives fine and it drove fine on my last engine. And it is a problem cause if falls on its face lean it surges... If it was driving perfect and just running lean I'd change jets and bleeds and correct the tuning problem, but it'snot a tuning problem.

Hyper4mance2k

iTrader: (40)

sudox, did you ever have any part throttle issues up a hill or anything. See someone locally with the same set up is having the same problem and he has an EFI pump.

mikey D

the car will run quite a bit differnt on and off the charge pipe.

the chargepipe and turbo add alot of restriction to the intake so you have to tune all the idle and offboost stuff with everything hooked up.

Sudox_E

Well, I've got some tuning left to do on mine. I get some bucking and wild a/f readings on part throttle. Sometimes it goes completely lean. I havent put my efi pump on yet, so this was all using a 16psi aeromotive fuel pump. What kind of carb are you running, and what's your jetting, if you dont mind?