MTC_75vette

I have been running a mighty demon 750 with annular boosters on my TRex ls1 with good results but I have nothing to compare it to. I did some research and came across prosystems new sv1 carb which claims to gain up to 50 more hp. With a $1250 I just dont have the funds right now to buy one but I spoke with James from prosystems and he told me that my 750cfm demon is too small for my set up and that they found ls motors love big carbs and high cfm. He told me if I buy a custom 4150 4 barrel carb from them I will see gains of 15-30hp. He told me that they would use a 950cfm body but have it flow around 830-840cfm. The cost $720 bucks and they claim its tuned for my motor and I can bolt it on and go for the most part with very little to 0 tunning needed on my end.


Does anyone have experience with these carbs or proof of these claims?

I guess I am simply asking do you think I will see the gains they are claiming I will get and if so is it worth the money. Truth is I can always sell my demon for a decent price if I gain this power from the PS carb.

ZONES89RS

iTrader: (25)

Well, I'm in for results. Idk if it will yield more hp, but Matt swapped his pro form 750 for a larger unit in his third gen 6.0 with a cam and heads and lost time.

3pedals

iTrader: (3)

he is deceiving you. Demon carbs are rated different than a comparable holley, and your 750 demon probably flows like an 800, or 850 DP holley.
I think your carb is fine.
I run an 850 mighty Demon and it is PLENTY big, and my 6.0l turns 7800 on the shifts

Pop N Wood

iTrader: (1)

Pro systems sells a quality product that they stand behind. Quite a few members here run them. The "no tuning" doesn't always work out that way, some guys have had to put a fair amount of time in to get them right.

MTC_75vette

Thanks for your response guys and im glad that my mighty demon is enough carb for my set up now I get to spend the money on those new heads I been wanting for the past few years lol.

MTC_75vette

So after deciding to keep my demon carb today I ordered my tfs 220 heads from vengeance racing can't wait to get them on. I dont have an air fuel tool but with the new heads do you think I should automatically jump up 2 jet sizes all around on the carb to compensate for the added air and power?

3pedals

iTrader: (3)

leave the carb alone for now.
SERIOUSLY consider spending $250 on a wideband O2 sensor setup, and you will be rewarded with almost too much info to get your setup running at full potential. there is still a learning curve to figuring our which carb tuning component effects which area of running quality, but you will learn quick. A decent carb tuning book will answer ALOT of questions.

Pop N Wood

iTrader: (1)

^^ +1

Having a wide band makes getting the main jets right one of the easiest things you will ever do to your car. Doing it without one takes a whole bunch of trial and error.

Getting everything else on the carb just right so all the part throttle cruising is smooth and sweet is what took me a bunch of time. The wideband was indispensable with that.

MTC_75vette

Thanks, I had my car tuned by a local shop with a wideband last spring and its running great. I was just curious if the head swap would want more fuel. For $250 your right probably a smart investment to have my own wideband.

speedtigger

iTrader: (16)

For the most part, carburetors are self metering. So, you should not get in any trouble like you could with fuel injection, but you still have to tune for optimum performance. Track, wideband or dyno. The drag strip is the final word, but the other two will get you close.

RATBOX

iTrader: (26)

I have a Pro Systems 926 E85 that I run on my 5.3 with a T rex, car absolutely RUNS with that carb on it. It's for sale also!

ATwelveSec02Z28

iTrader: (17)

I had ProSystems build me a carb for my 383.... Car ran very well with it.

When I hurt that engine, I contacted Patrick @ ProSystems and he recommended a jetting change. With that complete, bolted the carb down, and it ran 5.37@131...

Never did any tuning more than adjusting the idle screw.

Doug G

I called a few years ago to get my Mighty Demon 750 worked.... said they can't do anything to them as they already had "the tricks" done.

Talked to a BG tech who told me Demons are wet flow rated and Holleys are dry flow rated....thats where a lot of issues came from beings guys would size using the Holley chart, call jegs/summit/whoever and order.
He also said IF you put a 750 Demon on a flow bench at Holley, it would be in the 900-930cfm range (dry flow rated).