questions on a sn92 need help asap!!

well i have always been in to nitrous and i got a coupe now and my buddy has a sn92 blower i can pick up. a few things i want to know to better myself on them.....

what is there max boost?
what size fmu do u need for stock injectors?
what size fmu do u need for 24 or 30lb injectors?
what power gains would i see with a sn92 on a stock 88 notch motor with headers h pipe cat back?
what gears would i run?
what size pulleys make 6psi?
what size pulleys make 8psi or more?
what do i need to watch out for on a sn92 as far as keeping up on it things to do and not to do.
can a power pipe be used?
has anyone ever put a sn92 on a stock non mass air car and if so what did it make for boost hp and 1/4 mile if you ran it.
and how much should a nice sn92 blower complete kit polished go for? j/w

i dont think this blower is anything crazy but i am just looking to have fun it is a daily driver but im not afread to turn it up. well any info stories etc will be great so i can understand what i will be getting in to. thanks

Standard impeller on a stock motor, anything over 7 or 8 pounds is more heat than charge...

14:1 for 5 pounds boost is Paxton's supplied FMU calibration for 5 pounds...

C'mon do the math, it ain't hard: Boost pressure X FMU rate = targetted max psi. Use the fuel system calculator on Mustangworks if this is hard...

300-350 horse @ 5 psi, given the condition of the motor under the blower...

Whatever makes you happy, I have 3.55s...

C'mon, do the math, it ain't hard...

Keep the fluid clean with regular changes and a power pipe or some such can be used but is unnecessary in stock applications.

I run SD. I last 1/4ed the car when the blower was busted and needed rebuilding. 4 pounds boost pushed the 3350 pound hatch to a 13.0 at 107 mph on wasted slicks. That's ~320 horsepower on an engine that already had blown head gaskets, too.

It'll go for what people will pay. Polished is standard for the SN blowers, not an option. I'd pay no more than $1000 for a complete setup, and it would have to be mint, given how much new blower pricing has gotten aggressive.

The up side of the old Pax is it is perfectly suited to the stock or near stock 5.0 engine so it's not so peaky like "entry level" blowers today.

hey thanks for the help so what is a 12:1 fmu for? j/w cuz i can get one for a good price and i think the kit needs a new one cuz the one now leaks a little

12:1 is Vortech's setup for their A-trim blowers on stock engines. They blew 6 pounds in that configuration.

You know you can just change the calibration disc inside an FMU to whatever you want, right?

F=MA

You can also purchase from Vortech a rebuild kit for your FMU and they sell that kit also with a new calibration disc as mentioned.

so can i put on a vortech 12:1 and run 5-8psi with my sn92 and it will work good? how much is a rebuild kit and that stuff? and i prob sound stupid but i dont know this supercharger stuff.....what pulleys make what boost and this blower and what should my fmu be at for like 6psi and then for 8 ? mre you tell me the better. thanks again

The FMU is based on injector size not your boost level. The stock crank pulley 6" and a 4.25" blower pulley will produce 5psi

so if i wanted more boost then i leave on the 6" and put a bigger or smaller blower pulley?

You are heading for a head gasket blow or engine meltdown. You need to get your knowledge ducks in a row before you play with this stuff or you'll be learning how to rebuild engines.

Yes, you can spin the blower faster and produce a more boost, and a smaller blower pulley will do that. However, you must fuel for that additional air. The injectors will only handle so much before they are undersized, regardless of FMU ratio. 6-7 pounds in the upper limit for 19 pounders, period.

F=MA

so what pulleys make what boost? on the blower i mean what are the sizes to boost? and also the fmu should be 12:1 or 14:1 for stock 19s and like 6 maybe 8psi and one more thing if i put in 24's what should the fmu be set at, o ha one more thing do u need to change the timing and fuel pressure with this blower like nitrous?

At 5psi you can set your timing at 10 degrees and you will be fine unless your injectors lock up from 100psi being pushed on them. This is the reason a FMU is a risk because of the high pressure being forced on the injectors. If your going to change injectors go with 36lb units with matching MAS and be done with the FMU or if you get a tuning device(PMS, Tweecer, Chip etc.) then go with 42lb injectors. 3.75" with the 6" crank will give you about 8psi but you might run into belt slip on a 6rib at WOT. Anything over 5 psi and you will want to limit total timing at 24 degrees till you can use a A/F to verify.

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well i got it on i just need my fmu rebuilt or get a new one and put the tube from the charger to tbody, now where do i put the timming and what plugs do i us and what gap? i think there is a 6lb pulley on now not sure will find out when i start it i guess lol but let me know about the other things thanks for the help everyone

o yea i forgot one more thing what fluid do i put in there? and where can i get it part store? or i have to order it from paxton?

Type 'F' transmission fluid.
Set timing at 10 deg. with the distributor plug out.
Use Autolite #24 at .035 gap

On the speed of the supercharger, since peak horsepower on a 5.0 is 5600 rpm the car will still be under the 39,500 rpm limit if that is a concern with a 6" crank and 3.75" blower pulley size.

wellwhat set up should i put on for pulleys? i know the bottom is a 6 the kid said and i got to blower ones but i think they are like 4.25 and a 4.15 or something i just went from the center across and thats what it said how to i find out the size? put a string around it and the find out? sorry about keep on being a pain in the *** lol but i like to know about things i put on the car. if u could brake down what the boost is on each set up like 4.25 and a 6 = ?psi 3.75 and 6 =?psi and etc whatever ones you know off the top of your head you can tell me and if you know a better set up with pulleys and which ones fit let me know thanks

The truth is the pulley sizes are not the only thing that controls boost but your cam and heads also can cause the PSI to read higher and lower then the pulley should produce. Restriction is positive PSI. I can have a supercharger producing 10psi at 6500 rpm and change the heads to better flowing heads and at the same 6500rpm only produce 7psi. You now have more power with the new heads producing less boost. This is why different pulleys are offered in so many sizes because when you produced 10psi using a 4" pulley you will probably need to add a 3.5" pulley to producr 10psi again. The pulleys you have are probably 4.25" and 4" because the measurement is taken at the bottom of the groves not at the top.

ok well i got that the timing is going to goto 10 i need autolite 24's gapped at .035 and type f fluid. now should i change the fuel pressure or just leave it stock?

Leave the fuel pressure, that is for the FMU to deal with for now. You need to do this in steps so you don't spend the weekend changing plugs from fouling or replaceing a head gasket from going lean.

of well this is what im going to do tell me if it is not right....

2morrow put on fmu set timing at 10 leave plugs in there now and put f fluid in and the belt on , i might put 24's cuz i think the fmu i am getting is 10:1 or can i leave that with the 19s for now? you tell me how to set it up 2morrow lol thanks

If you put the FMU made for 24lb injectors it is possible you will run out of fuel at MID and WOT. How a FMU works I better explain. The ratio is how much fuel pressure is going to increase for every 1psi. 12-1..12 lbs @ 1psi 10-1...10 lbs @ 1psi
Soooo.. at 5psi boost your going to add to your base mustang fuel pressure(38lb) additional 60psi which makes your fuel pressure at the injectors 98lbs. Now you see the importance of a fuel pump and good injectors. This is also why your injectors could go static. Static means they lock up, either open or closed.
So if you use a 10-1 and only supply the injectors 88lbs of fuel which could be under what the engine needs since the manufacture figured you would use the 24lb injectors so you need less pressure at Mid and WOT with larger injectors since they can supply the fuel. This also goes for the MAS because it is metering air just like how the FMU measures fuel. Things need to match or you will be replacing engine parts. Now the other side of the equation. Paxton, Vortech and etc. also run your car really rich with the FMU so that it can cover the supply needed with 19lb injectors no matter if you changed other engine parts. This is why you will see people after or during a Dyno test adjust fuel or change from a 12-1 to a 10-1 FMU because the engine combination may just be to rich or lean at WOT with the engine tested.

What's that ticking sound? :teeth:

Please, figure this out before you beat on the car. I'm changing head gaskets right now because of a fuel pump failure I had a while back that detonated them to death. This was a couple seconds det on an engine with premium Felpro gaskets and ARP bolts.

F=MA

well i got a new fmu tonight it is a procharger one with a knob on top to adj for injectors. anyone know how many turns it will be for 19's? or where should i start and can i set it but reving the car to see the boost then set it or does there have to be a load on it to show boost. let me know what to do thanks

Check the Procharger forum ?

You need a hand pressure pump and that way the car is off. You can then adjust it watching a fuel pressure gauge and make sure the unit is giving you 12lb of fuel for every 1lb of boost to start. So on a pressure gauge you should pump to 5psi and when your showing 90-100lb of fuel pressure your set till you drive and see if it is to rich at wot at full boost. You really need a Wide Band A/F gauge to always make the best adjustments. Like said above you can ask the Procharger guys but the way I described is going to be the best to verify the FMU settings.

well i got everyhting together and dont have a gauge so i could not get it but i tried it in and then out when i go downt he roac and once it hits boost even 1psi it dies right on its face like someone turned the fuel offf. plus the timming is still at 13 and stock plugs are in. i know u all told me things to do before but can u relist what i need to do from start to finsih as in gap plugs timming and fuel. do i need a pump? thanks

few more things i need answered, first i am blowing the PCV valve out of the intake ever time and oil gets all over, anyone have that problem and how do u fix that. next is i found the directions for this **** box and it says it is for a mass air car my car is a 88 notch no mass are..... can i work around that or is that my big problem and i need to convert? if i have to i will if i can get a cheap kit if not i will sell the sn92 complete set up with is mint , so help me out and if it does not work out make me an offer if anyone wants it it is rebuilt upgraded etc i have all the paper work on it, but thats if i cant fix this well i will check back later thanks

All you need it to work on a SD car is a one way check valve you can get from NAPA and put it in line on the BAP sensor vacuum line. This will keep the car from jerking and not running correctly. That was a major not mention having SD.

yea i totally forgot about that so if i get that then it willl just make boost and pull and i can just fix the timing and have fun? so where does it go? in the vacuum line of the MAP senser, just put it in? also my other big problem now is y is my pcv valve keep blowin out of the hole and oil is going everywhere? how do i keep that in do i have to run it somewheres else?. thanks for the help let me know

Just install it inline of the BAP(MAP) sensor. Make sure you point it so that positive pressure(boost) does not enter the sensor. When boost reaches the BAP it thinks the air quality pressure has changed and sends a signal to the computer to stop entering fuel and it goes lean fast. Put a open element K&N in place of your oil fill cap. Do a search and others have discussed this in the Novi forums.

yea i just got one and put it on but it was way to small and when i started the car it would not run like the vacuum line to the MAP was totally off but it wasn't i tryed it both ways and it did the same. so i ordered a bigger one fromthe part store that says it is an air check valve and looks the right size, looks like the MAP senser vacuum line is like 1/4" so i would need one like that right? the one i got from napa has an end like a tooth pic so it must not be letting the vacuum come through. well let me know what im doing wrong and can u answer or help me on y my PCV inthe back of the intake keeps blowing out and pil is going everywhere? how can i fix that or is it just from when the boost goes in the intake and the car stalls down it pops it? thanks

is this like something i need the right size? i dont know what to get you have a picture of one or can you find one online for me......look...

http://cgi.ebay.com/ebaymotors/67-MU...spagenameZWDVW

or is this what i need? vortechs part # 4FD113-010. if so anyone know how much they are and where i can get one? i heard tho the lean the car hout how do you fix that?

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Originally Posted by SN92NOTCH

yea i just got one and put it on but it was way to small and when i started the car it would not run like the vacuum line to the MAP was totally off but it wasn't i tryed it both ways and it did the same. so i ordered a bigger one fromthe part store that says it is an air check valve and looks the right size, looks like the MAP senser vacuum line is like 1/4" so i would need one like that right? the one i got from napa has an end like a tooth pic so it must not be letting the vacuum come through. well let me know what im doing wrong and can u answer or help me on y my PCV inthe back of the intake keeps blowing out and pil is going everywhere? how can i fix that or is it just from when the boost goes in the intake and the car stalls down it pops it? thanks

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you need to run a different oil cap... the plug in breather style will help fix the PCV problem.

ok i will try that now what about everything else?

I run SD. Just drill a 1/16ths hole in the the vac line aft of the check valve, in line to the MAP. I stuck a nitrous jet in there to keep the hole open but it worked before I did that.

PCV has to have the supply side at the throttle body killed, just like any 5.0, MAF or SD. Cap it off ant the TB and leave a bit of hose on the nipple from the filler so the PCV has an inlet supply of air.

i thinki am just going to convert to mass air, that i think will solve that problem now what are you talking about to do to the pcv? let me see if i get it....leave it all connected to the intake like normal and the nipple off the tbody that goes to the filler oil neck take that hose off plug the tbody and leave that neck open?


well i pluged the tbody nipple and then in the directions i seen that they say run a 3/8 hopse from the filler neck to the plastic cover over the air filter and thats what i did./ will that solve my pcv problem? if so would it help even more to put a breather on top of the neck?

after u answer those lol i then still need to set my FMU, it has the adj twist on it but my fuel gauge is under the hood and dont u need to be driving it to find out what it is or can i rev it ? and what should i do to the stock fuel pres bump it up? if so to what?

As explained above use a pressure pump you can even rent one from Autozone or Advance Auto PArts.

and where and how do i use ti car running not? where to i pump from?