Okay ive decide for now im going to try to put a roots blower on my 305 tbi car or maybe 305 tbi if i save enough.Okay this is what i need i did a search already but nobody really says the item number of the dupercharger also the one that fits on the 305 will it fit on a 350?Also my car has 116 thousand miles and im going to do a rebuild but since im there what are some of the things i should buy for 305 or if i keep the 350,I was thinking bottom end stuff and a Lt1 cam for the 305 but what cam for the 350 and what should i do about the 2 bolt mains?

Also im thinking about using a 100 shot of nos to make things more fun and the highest octane gas i will use is 92 or 93.thats all they sell around here.

 

hey dude


i have thought of that myself. But the problem with that is going to be how are you going to get the ECM to see the boost? TB cars have a 1bar map that reads only vacuum. in order to get it to read the boost you will need a 2bar map sensor. In order to get the ecm to read a 2 bar map sensor you will have to have the E-prom code hacked and fixed so the ecm will understand it. Then you will need to get bigger injectors to handle the more power. inwhitch you will still need to have the e-prom reprogrammed to see the new bigger injectors. also a new feul pump so it can feed the engine.

so all in all GET a 85-87 TPI car with a mass air meter on it and super charge it makes it alot easier.

There is some other things that will need to be addressed also but the ECM is the biggset thing holding it back.

you might be able to contact hypertech and see what they can doo cause back in there early 90 they made a supercharger kit for the 454 TB trucks. see if they can do a patch code on your ecm. if you can get that you will have it made

 

tbi sits on top of the blower, and the map sincer is above the blower also, it sees no boost, only vacume. that is why you can plunk a couple of carbs on top of a roots blower.

i have looked into this swap very much. the best bet is to get a 900cfm holley command 950.

when i talked to the weiand (holley) techs about this, they said that the standard 4bbl carb version would work, but i would have to modiffy the spacing of the pulleys to work with the serp. belt setup. i could not get an answer as to the pullies used for the truck. maybe another phone call . i think $$$ wise getting the universal long nose version is the best bet. you may need to have a pulley spacer machined for the nose of the blower, but other than that everything should bolt on. i think the command computer system is the way to go, i hear it is pretty easy to tune and work with. and the 900cfm TB would really help. i think even a 670cfm unit would really choke a blower.

also, do a search in the power adder board, Kingsta1on had a 144 blower with a 355 and 900cfm TB, he put down 500hp, and still got 20+ mpg on the freeway.

 

From what I've been told by Jonas Bylund is with a supercharger you don't need the 2 bar map, there are ways around it, but with turbo you would need a 2 bar map. Besides the fact he's wanting a roots style I thought I would throw that in.

You would definately want bigger injectors and chip tuning, and maybe even a fmu from vortech. Not sure if you can plug a fmu in below the sc with a roots style?

You might talk to Jonas, he's the guy to talk to. He's running a crossfire motor with a vortech supercharger plus he's done the winaldl program and alot more so give him a pm and see what he says.

 

well to boost reference the ECM you will need a 2 bar map sensor. our cars have a 1 bar map sensor. a one bar map sensor reads only vacuum which -14.7. then the map sensor converts than vac into voltage ranging from .5 volts to 5 volts on the 1 bar map.

Now on the 2 bar map sensor it reads -14.7/ +14.7 thats how you get a 2 bar map. then it converts the voltage from .5volts to 5 volts over the entire 2 bars.

In order to get the ECM to understand the change in voltage across the entire 2 bar range the Code in the chip will nneed to be overwritten to understand the variance in pressure/vacuum vs voltage.

in referencee i forgot that he said a roots style blower. I was thinking about a centrifugal charger and blowing thru the top of the TB for the need to boost reference the map sensor anyhow.

I'm curious to how he boost referenced his ECm using a one bar mao sensor. unless he programed the PE table himself


also whether you used a centrinfugal charger or a turbo if you start makes boost the map will not see it and if the map can not see it how can the ECM control fuel correctly. I can unnderstand maybe disregarding it at WOT using the power enrichment tables but what about say 1/4 throttle and you start pulling a load and boost goes up how can the ECM control the fuel since it is not relying on the PE tables.

i'm tring to understand i'm from the turbo buick world on the boost and how the ecm control fuel and the TBI and boost thing i has got me puzzled on how hee has got it running ?

 

that is where the FMU comes in, it refrences the boost and raises fuel pressure according say you set it up so that it adds 2psi of fuel for every 1psi of boost. that gives you 1psi of fuel more per pound of boost. and is basicly like having a PE fuel adder. only thing that won't do is add timing.

 

Which is where a MSD BST comes in to work well with a FMU. The Boost Timing Master from MSD will take away timing with every psi of boost it sees.

 

alot of bench racing going on here...

if roots blowers dont work on tbi why does holley sell one???
the commander 950 would most likely be a much easier ecm to tune but the cheapest one is also 1350.. for that go tpi.. and put a centrifugal sc on your car..

you might think the roots is cheaper but in the long run it might be more expensive.. YOu might never run right or anything...
Shawn