Starting a new post since my old one got a bit cluttered.
I want to put a vortech S trim supercharger on my 383 and need to size the injectors. I am going to limit the boost to 5psi, I think that is what the pullys I have now would put out anyway. The online calculators ask nothing of engine size, only HP. Is 500 BHP a reasonable estimate? I am not looking to milk every ounce of power from the engine, it is going in a 51 Ford pickup and will never hook up anyway.
383
10.5 compression
comp 503 cam
stock heads with supposedly a 5 angle valve job
shorty headers (all that will fit in this chassis)
forged crank, H beam rods, forged pistons

I will have to send my PCM out for a tune once I have the injectors set. I am running the vortech FMU that runs a trex fuel pump to raise fuel line pressure under boost, I assume 1psi per pound of boost?

Thanks for any help!

 

http://www.rceng.com/technical.aspx

there is a good injector calculator on this website^^^
If you have the correct sized injectors you shouldn't need to rely on the FMU to adjust the fuel flow.

 

Thanks, that was the site I used, just didnt know if 500HP is a reasonable value to use for sizing.

So go larger with the injectors and ditch the FMU? What about the secondary inline fuel pump then? Not needed?
I have a set of 42s now with the FMU, if they will flow enough I would like to use them to save the cash. If they are not large enough then I will buy new ones.

 

What in tank fuel pump?

42lbs should be fine on mild boost no FMU especially when handicapped with unported heads and shorty headers.

You understand this plan is poor right?

 

New in tank pump from a 1995 caprice LT1, stock, so should be regulated to 43psi at the rail with the factory Z28 regulator. Then I have the secondary Trex pump inline with that which would be tied to the FMU. Basically all the parts that would come with the vortech kit.

Heads are supposed to have a 5 angle valve job, but who knows what is really done, I just plan on nothing special. PO also said they were ported, but I dont believe anyone anymore without paperwork so again I dont consider it done.

I also have a new CC305 in the box as well if that would help at all, but I like the choppy idle of the 503.

Is 500BHP a reasonable estimate or too high?

What do you consider poor that should be changed, that can be changed? Seriously, because if I throw this into a nova or 55 chevy or whatever I may as well fix what can be fixed.

 

Drop the tank, remove that stock pump.

At the very very least, toss in a 340lph or 400lph pump. Ditch the stupid booster pump and FMU. Get a quality stock fuel reg or aermotive, just has to be 1:1.

Buy either 60 or 80# injectors, their relatively all the same price.

5psi, won't get you 500whp IMO, maybe mid 400s pending how bad it reacts to the high SCR. Invest in a quality meth kit and drown that bitch at WOT. I hope you have a quality intercooler?

 

If its the 114 lsa cc305, those are a half decent off the shelf boost cam. Not great but better than a cc503 for the application. That compression isn't undoable with boost but e85 or meth will be your friend.

 

Ok so looks like I have too much scr for this to work out. I am going to pull the heads and verify what Pistons are in there and see if I can get down to 9:1 before doing anything else (may be possible with current pistons). No need to blow it up, also the cc305 I have in the box is the 114 lsa version.

How does this sound, any better?

Replace in tank pump with wahlbro 255 pump, remove inline trex pump
get adjustable aftermarket fuel pressure regulator
get engine to 9:1 compression or close
replace cam with CC305 114LSA
run the 42# injectors and check o2 readings to know if I need larger?

I am not sure if I can improve the exhaust much, shorty center dump or mid length style headers may be all I can fit. Does that sound like a plan for success or still need other changes to make the engine live reliably?

Thanks for any help!

 

I would use the 503, those pushing rediculously wide LSA for a mild blower engine don't comprehend the difference engine wise blower vs turbo. A turbo has huge back pressure to deal with, asnwell as the inlet boost, a blower engine even with mediocre exhaust doesn't have the back pressure to contend with and is closer to just having high atmospheric pressure so under normal mild use like this an "NA" can is fine. Kind of like someone arguing for a nitrous spec can for a 100hp shot.

 

A blower car still have reversion issues if you are fighting a large backpressure. Will that be valid at a small head unit and 5psi? Doubtful.

The 255lph is to small.
42# is too small.

If you want the big power numbers, you gotta pay for it.

 

Thank you 96capricemgr, if I can run the 503 I would like to.




Then how was the original 355 running with this supercharger using the factory Z28 pump, T-rex, FMU, and 42 psi injectors?
How can I be reading about guys running 10psi with 36 pound injectors and a single wahlboro spinning 6500 RPM?
The calculators show that 42s will do 500HP with the FMU, why would I ever need 80s? How can this vortech kit be listed at 400HP
with a stock LT1 using 24# injectors and a stock cam?
I can see how not overdriving the injectors would be a good thing, but I want to keep part throttle response down low as well. Seems like an FMU would be the best of both worlds?
Why is a single 255 pump not good enough for 500HP when I read about guys doing just that?
I am not a teenager with his first car. I would like to understand the pros and cons of each system so I can build a system rather than just copy what someone says.
I have read about guys running 10.5 engines with boost with no issue. I have read papers showing the linearity of boost as opposed to the non linear cylinder pressure spikes when running a high SCR. I know running the 503 cam will bleed off cylinder pressure which can help down low but probably will not help me since the SC wont make boost until the cam starts working.

All I want to do is get the vortech on this 383 and have it run reliably so I can go WOT without worrying about popping a head gasket or detonating. 5psi is fine, I dont care what HP I make, but I have to guess to get an injector size. I appreciate any help from those who
understand how the complete setup works and can discuss the reasoning behind the parts.
I have the vortech water cooled aftercooler as well if that matters, but didnt know if it would be better to just go with a front mounted intercooler.

The way I look at it is the vortech kit on a stock LT1 was rated at 400HP. I dont see going from a 350 to a 383 and a cam swap getting me 100HP, so maybe I will be at 450HP? I dont care as long as I can drive it without worrying about it blowing up all the time.

 

I am not saying it won't work any other way, I try to recommend what I think will be the best option. Of course you will find people who get by with minimal work, and you will also find lots of melted pistons and trashed motors cause of lean spikes and super hot EGTs. All a balance of risks you are willing to take.

Your previous setup may have gotten by fine, or you may have been running super lean from lack of fuel up top. IDK either way since its not my car so I can only err on the side of overkill. I don't know why you are fixated on part throttle response aspect, I have no issue whatsoever with that, and neither does the other local car I know that runs large injectors. Newer high Z injectors are not the old fashioned low Z stuff.

I am only suggesting stuff that you can buy once, have a quality working fuel system and be able to grow with it. You said it yourself, why have a forged bottom end and not use it? So I can only assume you won't stop at 5psi of boost, and what happens when you want more power but are out of fuel? Regardless of my ramblings, you are more than likely right, I am overkill and what you had obviously worked. Just my opinion on stuff is all.

 

Not the same at all.

A boosted setup regardless of turbo or supercharged will require more thought in cam selection than pretty much 90% of nitrous setups.

As stated the possibility of him staying at minimal boost levels isn't likely. Better to swap in a part that is available while nothing is completely installed that will be less counterproductive to the setup in the long run. He will only be out for time, gaskets, and rtv. Neither cam is ideal for the application but one would lend itself better depending on long term goals.

 

I agree on doing it once, you are all right on that. I am also not trying to "cheap out", just trying to use what is on hand IF it makes sense.
And please dont take anything I type as an argument, like I said I want to understand and learn. I am going to pull the heads and if the pistons are in there that I think are there then I can get close to 9:1 with felpro 1074s and stock CC heads.
What do you consider the compression limit taking into account that I have the aftercooler to lower IATs?

 

Your SCR and DCR will dictate how tight your tuning window is and then your IAT temps will need to correspond to that window. If you run a higher SCR you better have super low IATs cause you cannot be pushing much timing or you will start to ping/rattle crowns off. I am assuming this is regular pump gas correct?

IMO its better to have a lower SCR that allows for a lazy tune and a wide range of IATs. 9:1 may be a tad low, see if you can get around 9:5 range, thats where my motor sits at and with 10psi it does pretty well for itself. Don't let people tell you stock heads are holding you back, get a nice port job on em if you can swing it and use em.

Either way, make sure you verify with your tuner your IAT/timing tables are conservative and not some crazy *** numbers. If you are worried about WOT IAT or fuel issues, invest in a water/meth kit and run straight M1. You won't need a large nozzle but that should provide fueling up top if you do see that you are running out of pump/injector. Or if you do have fuel but are worried about IATs, switch to a 50/50 mix or a mix favoring water.

 

here is the deal...I made the mistake you are about to 12years ago when prochargers were first hitting the streets. I put a P1sc on a pretty much stock 96 Z28 M6. The car had about 30k miles at the time. I tried running the fmu and in line pump with the supplied kit. The car ran ok, trapped about 114-115 on 7 lbs. The car was a problematic ***** and I eventually took it to a shop. The entire kit sucked except the head unit. They put in a walbro 255 and 42lb injectors then tuned the car after fixing all the little problems. It made 426 whp and 425wtq, the down fall was it had a cracked ring land in the #8 hole by that point.

Instead of taking the advice of the shop and rebuilding the stock block, I opted to buy a forged 383 shortblock. I left the heads and intake stock, then put shorty bbk headers on it. The car never worked right from that point on. P1sc was maxed out for the larger displacement by 5000rpm and the car would still only make around 440 whp. The setup flat out sucked...I did not know any better at the time because nobody else was doing what I was trying to do back then. At least very few were. I sold the blower kit and had the heads and intake ported, then 1 3/4 LT's. While it did not make quite as much power, the car had a better power curve, drove better, and was faster.

If you want to go forced induction that is fine, but listen to the folks that have been down that road before. Your planned setup is nothing but failure in the making.

If you want to go 383 then port the heads and intake, put long tubes on the car, ditch that tiny head unit, and put a real fuel system in the car.

 

Well if the S trim is too small for a 383 then that is the last straw, I will throw it on the shelf for another time and build a 355 for it. No worries, maybe next year I will drop it in a Nova or something else that has room for a full flowing exhaust system.
Going to run the 383 as is for now, it will already be too much power to hook up in an old pickup, even without long tube headers.

Thanks for the help, I will be back..