Tuning a supercharger

[CManT1914]

Okay, I'm looking to get a Vortech V1 kit. I searched, but couldn't find quite what I need to know. Will I be able to get the car tuned good just by using the FMU it comes with? Or will I need to get a custom tune? If I use the FMU, what size injectors will I need? I have heard that 42 lb injectors with a custom tune is a lot better, and that the FMU is garbage. Why is this method superior to using the FMU?

 

[PNY PWR]

How much boost will you be starting off with? I've got 19# injectors and running the 12.1 FMU, Kirban AFPR set at 39psi. Everything is working pretty good at 6#'s of boost. I'm running a 155lph fuel pump too, just for security.

 

[TheUser]

It's better to get a poweradder car tuned on a dyno - using wideband o2 sensors - so that they can watch your air/fuel ratio and make sure you don't run lean up top or anything. You don't have to get it dyno-tuned, but ideally you'd want to. With 6lb, you'd prob be fine, but any more than that and I'd definately look for the closest dyno shop.

A lot of people say FMU's are the easy way out instead of tuning the car properly (dyno, etc).

 

[Darkhorse845]

Get a good dyno tune!

 

[CManT1914]

Well the Vortech V1 is a 6-8# kit. Why the 6-8? Does the amount of boost fluctuate depending on weather? Like how dense the outside air is? Either way, I'll be running around 6 lbs of boost. PNY PWR, you're using stock injectors? So I could use my stock injectors with the fuel pump and FMU it comes with and be good to go? I don't mind getting it dyno-tuned, but I was wondering if I would need bigger injectors.

 

[UnderPressureGT]

i suppose if your running 6-8 pounds if boost, you should be fine with no tune and the FMU... the FMU does have tendencies to run pig rich up top... i would know!.. it is much better to run bigger injectors and no flmu with a custom tune, buit for little boost, its not even necessary.. if your running only 6 pounds of boost, then your 19s are fine with the 10:1 fmu disk

 

[BlackFox5.0]

Forget the FMU, thats a bandaid for a correct tune. Junk.

Use at least 36# injectors and get an S/C Calibrated Pro-M MAF for your injector size. Those injectors are good for a decent amount of power, and should handle up to around 375HP.

 

[CManT1914]

Well I don't want to have to shell out more money for injectors if I can help it. So I'm thinkin since I'm only gonna run 6 lbs then I can get away with just the high-flow fuel pump (whatever one comes with the kit), 19 lb injectors, the FMU from the kit, and maybe an AFPR? An AFPR is a lot cheaper than injectors, so I think I will go this route. I shouldn't have a problem like that? At least for a little while?

 

[UnderPressureGT]

Forget the FMU, thats a bandaid for a correct tune. Junk.

Use at least 36# injectors and get an S/C Calibrated Pro-M MAF for your injector size. Those injectors are good for a decent amount of power, and should handle up to around 375HP.

375 hp? thats it from 36 lb injectors??? 9im making around 380 with my 24's...

I have a question about this chart...... this fmu kicks my fuel pressure up around 80 psi..... if you look at 24's and 80 psi, does that mean im good to around 507??????

 

[BlackFox5.0]

I do not like to run higher pressures than stock, the injectors not made to run at high psi. Keep running an injecotr at 70psi and tell me how long it lasts. I just like to keep it at 38psi, and let the computer do the adjustments. if i need a little more, sure I'll bump it a little, but not excessively, just to meet a desired AFR.

36# injectors are supposedly good to 523hp with a supercharger, but why push the limits like you....whatever...

 

[CManT1914]

Okay, so assuming this chart is moderately accurate, what PSI would I need to set my fuel to to compensate for 19 lb injectors? I really don't know what kind of power 6 lbs would put me up to. I'm thinking I could bump fuel pressure to between 60 and 70 psi and be good until I could throw some 30 lb injectors on and get it dyno-tuned?

 

[UnderPressureGT]

when i had my 19's vortechs fmu uses a 10:1 disk... until i get big enough innjectors soo i dont need an fmu, i will be running what i have now... i actually got in a little arguement with someone in the motorsport dept of downs ford bc they said i NEEDDD a fmu and i told them that their band aid fixes for not having a fuel system.. oh well ford is always right i guess i know nothing. pft

 

[Daggar]

Both are correct. Yes... you can support a considerable amount of HP with 19 lb injectors at an elevated FP and 80 to 100% injector duty cycle. It is also true that the injectors were not designed to run continuously at those pressure. It's also true that an FMU is "bandaid" fix an actually takes the AFR out of the hands of the computer when you're under boost. Don't even consider attempting to "guess" what the AFPR needs to be at when using an FMU and AFPR together. It's a waste of time and you'll never get it right anyway. It varies from setup to setup. In addition, just cranking up the FP through the AFPR is no way to fix anything anyway. You do not need an AFPR when using an FMU. By cranking up the fuel pressure, you're increasing that pressure for ANYTIME the car is running. Not just under boost. The computer will eventually revert back to a more normal fuel curve by adjusting down the duty cycle of the injector so that the AFR through the factory 02 sensors is correct. The ONLY time adjusting the AFPR will do you any good in this scenario is if you have a fuel pump installed that can't hack the fuel volume necessary to keep up with the car in boost. Having to do that is a bad thing for allot of reasons,, most notably of which is that, that particular fuel pump should not be there if it's unable to handle to volume required at the deseired fuel pressure for the amount of boost you're running. Leave the FPR alone. There's nothing wrong with the one you've got. Let the FMU and the fuel pump do their jobs. If you need some adjustability in the system then put an adjustable boost-a-pump in to control the voltage going to the pump. The IDEAL setup would be to have pump, injectors, and properly programmed computer, installed so that the computer can monitor and make the correct adjustment to the AFR across the ENTIRE power range. Granted, we all cannot afford all of thes mods at the same time and it's the reason FMUs are made. Once again for the folks in the back row.... GET A WIDEBAND 02 SENSOR AND READER! That in combination with a vac/boost guage, and fuel pressure guage, will enable you tune it as best you can using an FMU. The Boostapump will allow you to give just that little extra gas needed to avert a lean condition at full boost. I think that's it. Lemme know if I left anything out.

 

[UnderPressureGT]

tell me something man... my fuel rpessure is set at 39 with VAC off..... at idle, it smells PIG rich.. should i lower it around 36??? i mean i do have a 10:1 disk sooo i should be getting plenty of gas up top... but there goes the word SHOULD... i dont have the air fuel setup until xmas soo i have no clue whats going on right now.... all i know is that up top i have NO detonation and it runs good..... at an idle it smells pig rich and throttle response is as if it were too rich, not smooth at all

 

[Daggar]

KEY WORDS:

all i know is that up top i have NO detonation and it runs good

Why on earth would you want to run the risk of leaning out too far under boost? When you get the AFR meter installed then you'll be able to adjust safely and not run the risk of detonating and hurting something expensive.

 

[mustangdaren]

There are several different V1 Vortechs. V1 is just the type of gearbox. If you get the SC-trim it is rated at 6psi and the S-trim is 8-10psi with the stock pullies. I think you would be pushing your luck with the S-trim and 19lb injectors. I am using an SC-trim. With a Pro-M 75mm Maf, 24lb injectors, 10:1 FMU disc it ran pretty good, making 5psi boost. I switched to an 80mm Pro-M MAF with supercharger calibration, 42lb injectors, UPR powerpipe and ditched the FMU. It made a world of difference. I guess getting rid of the junk intake hose and filter that comes with Vortech kits makes it flow so much better. It now makes 7psi boost with no pulley changes. I would have to say if nothing else get you a powerpipe when you buy your supercharger. It is much easier installing them before the blower head is mounted and they are worth every penny. Pick you up a high pressure Walbro 255 pump also. Make sure it is the high pressure. (GSS340 or GSS342)

 

[CManT1914]

There are several different V1 Vortechs. V1 is just the type of gearbox. If you get the SC-trim it is rated at 6psi and the S-trim is 8-10psi with the stock pullies. I think you would be pushing your luck with the S-trim and 19lb injectors. I am using an SC-trim. With a Pro-M 75mm Maf, 24lb injectors, 10:1 FMU disc it ran pretty good, making 5psi boost. I switched to an 80mm Pro-M MAF with supercharger calibration, 42lb injectors, UPR powerpipe and ditched the FMU. It made a world of difference. I guess getting rid of the junk intake hose and filter that comes with Vortech kits makes it flow so much better. It now makes 7psi boost with no pulley changes. I would have to say if nothing else get you a powerpipe when you buy your supercharger. It is much easier installing them before the blower head is mounted and they are worth every penny. Pick you up a high pressure Walbro 255 pump also. Make sure it is the high pressure. (GSS340 or GSS342)

I'll be looking for the SC-trim, the one that makes 6 lbs of boost stock. I believe the supercharger kit comes with a high-flow fuel pump, but I don't know how big or how good it is. I have an 80mm Pro-M MAF calibrated for 19 lb injectors, I'll hook it up when I do the SC. So for now, I'll just use the FMU, with the stock injectors, whatever fuel pump the SC comes with, and my 80mm MAF. I'll probably get a powerpipe later down the road.

 

[BlackFox5.0]

tell me something man... my fuel rpessure is set at 39 with VAC off..... at idle, it smells PIG rich.. should i lower it around 36???

Stock pressure is 38psi. When someone tells me their car smells rich, without having cats especially if it has no air pump, I just have to laugh...... My car smells just like a new cars exhaust, hell it's most likely cleaner too, but of course it's 100% street/emissions legal.

IMO, if you can't afford everything you need for a blower, then you really shouldn't have one. In the end, you might just end up paying more money rebuilding the motor after you destroy it from improper tuning. Tuning nowaways is no long just a few adjustments of the carb. You still have to go straight to the where fuel delivery is controlled, which is now the ECU. Any piggyback chips or anything are also bad, you don't want to emulate the signals to/from the computer. You want to control them.

 

[UnderPressureGT]

Stock pressure is 38psi. When someone tells me their car smells rich, without having cats especially if it has no air pump, I just have to laugh...... My car smells just like a new cars exhaust, hell it's most likely cleaner too, but of course it's 100% street/emissions legal.

IMO, if you can't afford everything you need for a blower, then you really shouldn't have one. In the end, you might just end up paying more money rebuilding the motor after you destroy it from improper tuning. Tuning nowaways is no long just a few adjustments of the carb. You still have to go straight to the where fuel delivery is controlled, which is now the ECU. Any piggyback chips or anything are also bad, you don't want to emulate the signals to/from the computer. You want to control them.

not to argue or say ur wrong, but ive had the blower on my car for roughly 20K miles... if it wasnt tuned right, it should have blown up a long time ago.. at least a headgasket!

about the running rich... ive smelt a few other cars withoffroad pipes and no smog pumps and they smell nowhere near as bad as mine does... mine has a very strong gas smell..

 

[PNY PWR]

IMO, if you can't afford everything you need for a blower, then you really shouldn't have one.

That's such bull. CMan, you can do what I'm doing. Start out at 6#'s of boost with the stock injectors and FMU. Run you a good high flow 180* t-stat. Start the timing out a 6* and FP at 39psi. Run Autolite 23's , I left them how they came out of the box as far as gap, checked them all and .35 would slip in there/.40 wouldn't, so they're in between there somewhere.

You start learning a bit about tuning pretty fast as you go. You don't need to spend the extra $500 for MAF/injectors at this point. Forget the dyno tune because you're going to up the boost and upgrade your fuel sytem later anyways. Save the dyno tune for when you get to that level. Unless you want to spend the $300-$500 twice for the tune.

My car is running great with the setup I mentioned above. I do plan on upping the boost and upgrading the fuel system later on. My point is, don't be scared to get into it based on what the experts are saying. Put a 6# kit on it and tune it safe at first and have some fun with the new power/learning about tuning with boost.

I see you have a MAF sensor in the box. Keep that one, it's perfect. What injectors is it calibrated for?