• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

turbo fuel ????'s


Dsc Motorsports

New Member
Joined
Nov 19, 2007
Messages
34
Reaction score
0
Points
0
Age
36
Vehicle Year
1991
Make / Model
Ford
Transmission
Manual
im in the process of turboing my 91 ranger and just wondering on a safe size injector to run i wont be running but 7psi and i dont want to go over board with it!
 


Bill G

Active Member
RBV's on Boost
Joined
Nov 28, 2001
Messages
10,828
Reaction score
4
Points
38
Age
56
Location
A $20 fuel surcharge from Tucson
Vehicle Year
1992
1984
Make / Model
Ford
Engine Size
2.3, 2.8
Transmission
Manual
You should be safe with 19lb yellow top injectors from a 5.0 mustang
 

Dsc Motorsports

New Member
Joined
Nov 19, 2007
Messages
34
Reaction score
0
Points
0
Age
36
Vehicle Year
1991
Make / Model
Ford
Transmission
Manual
hmmm! think itll be enough!
 

Bill G

Active Member
RBV's on Boost
Joined
Nov 28, 2001
Messages
10,828
Reaction score
4
Points
38
Age
56
Location
A $20 fuel surcharge from Tucson
Vehicle Year
1992
1984
Make / Model
Ford
Engine Size
2.3, 2.8
Transmission
Manual
If your'e not going to run over 7 psi, your stock injectors will work. But to be on the safe side, you can add the yellow top injectors. There was a guy here named George who ran 18 psi with the yellow tops and he said it never ran lean.
 

V8RangerBoy

New Member
Joined
Dec 3, 2007
Messages
203
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
A typical "ballpark" calculation for injector size is:

(Flow * max duty cycle * cyl #) / BSFC for the motor.

In other words, multiply the flow rating of the injector (lb/hr) times the maximum duty cycle (typically no more than 80% for reliable operation) times the number of cylinders. Then divide this value by the BSFC (brake specific fuel consumption - Google it if you want, it's a wierd value). BSFC for a normally aspirated motor is about .5. Supercharged - .6, turbo'd - .65.

So, for my truck for example, the stock injectors flowed 19lb/hr. I used 80% duty cycle, and it's a V8. This was also in prep for the turbo, so I used .65 BSFC. (19 * .80 * 8) / .65 = 187.5 - the stock injectors were good for roughly 190hp under boost. Obviously, I knew they had to go. An N/A 5.0 makes more than 190. Went up to 39lb/hr's - moved the ceiling up to about 385hp.

Keep in mind these values are by no means exact, but it will let you know if you're in the ballpark. Or way the hell out for that matter! Are you turbo'ing a 2.3 or what?
 
Last edited:

Dsc Motorsports

New Member
Joined
Nov 19, 2007
Messages
34
Reaction score
0
Points
0
Age
36
Vehicle Year
1991
Make / Model
Ford
Transmission
Manual
yea its a 2.3L 5-speed got a tdo4 turbo. so if i keep the boost down i can prob get by with the stock injectors for a while? what do yall think i should do on the mass airflow sensor??and how much can the stock one take before i becomes useless?
 

V8RangerBoy

New Member
Joined
Dec 3, 2007
Messages
203
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Yes, with low boost stock injectors are probably fine. I'm not extremely familiar with the 2.3 turbo setups or with the 2.3 itself, but from what I've gathered from briefly reading around the stock injectors seem to hold up well for low boost. Whatever you do though, stay away from the FMU route like a Vortech blower kit uses... nothing but bad news with those - they're a super-halfass way of getting extra fuel.

As for the MAF, I would either A) find the specs of the MAF off of one of the 2.3 turbo coupe's to compare with, or B) just get a MAF from a turbo coupe. Those are bound not to peg out, and I would imagine that the wiring is most likely plug-and-play since both meters would be pre-OBD II.

The range of the meter also depends on how it is set up. Mounting the meter draw-thru will give the meter slightly more range before pegging than mounting it blow-thru will. The drawback here is that mounting draw-thru means that you have to not run a blow-off valve, recirculate the blow-off valve, or tune for the little hiccup that venting out the metered air will cause. If you choose to go blow-thru though, make sure that there is at least 6"+ of straight tubing before and after the MAF. Cutting corners here will cause you some serious headaches later. Definitely invest a fair amount of time researching this area - the MAF is very very important from both a tuning and driveability standpoint.
 

Dave R

New Member
Joined
Aug 6, 2007
Messages
658
Reaction score
2
Points
0
Location
In the snow belt
Vehicle Year
1953
Make / Model
Kaiser
Transmission
Manual
As for the MAF, I would either A) find the specs of the MAF off of one of the 2.3 turbo coupe's to compare with, or B) just get a MAF from a turbo coupe. Those are bound not to peg out, and I would imagine that the wiring is most likely plug-and-play since both meters would be pre-OBD II.
A nice idea but, unfortunately, turbocoupes did not use MAF meters. They used a modified speed density system and yes, the VAM (Vane Air Meter (the modified part of the SD system)) does peg out. Ford didn't 'perfect' their MAF systems until late '90/early '91.
 

Dave R

New Member
Joined
Aug 6, 2007
Messages
658
Reaction score
2
Points
0
Location
In the snow belt
Vehicle Year
1953
Make / Model
Kaiser
Transmission
Manual
Then divide this value by the BSFC (brake specific fuel consumption - Google it if you want, it's a wierd value).
Nothing really weird about it, it's a measure of how efficiently any given engine converts fuel into horsepower. The closer the number is to zero the more efficient the engine is, the further away the more wasteful it is.
 

V8RangerBoy

New Member
Joined
Dec 3, 2007
Messages
203
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
Nothing really weird about it, it's a measure of how efficiently any given engine converts fuel into horsepower. The closer the number is to zero the more efficient the engine is, the further away the more wasteful it is.
Wow, finally someone with a decent and simple explanation :) good to know.

Bummer on the MAF deal. Haven't heard of SpeedDensity systems consistently providing results to jump up and down about :( could be wrong though, could have just been set up incorrectly.
 

Dave R

New Member
Joined
Aug 6, 2007
Messages
658
Reaction score
2
Points
0
Location
In the snow belt
Vehicle Year
1953
Make / Model
Kaiser
Transmission
Manual
Wow, finally someone with a decent and simple explanation :) good to know.
I never really understood why people think it's some 'magical' thing. And BTW, the type of induction has nothing to do with an engine's (B)SFC. Most modern computer controlled engines are capable of getting into the .50-.55 range. T'is one of the reasons that there have been no great mileage advances in vehicles for the past 15 years or so. My '93 Escort commuter car gets 32-34 MPG average driving, as do most 'modern' vehicles of it's size.

Bummer on the MAF deal. Haven't heard of SpeedDensity systems consistently providing results to jump up and down about :( could be wrong though, could have just been set up incorrectly.
Other than Mega-Squirt, and perhaps a few of the limited production motorcycle builders, nobody uses SD anymore. The VAM on forced induction engines was a way to tell the computer how much air was being forced into it, since, obviously, the simple rpmXdisplacementXMAP calculation wasn't going to cut it, especially as Ford chose to use a MAP sensor that couldn't read pressure. MAF systems are better, in the long run and thanks to the modern vehicle computer's ability to be reprogrammed much easier to get right.
 

Dsc Motorsports

New Member
Joined
Nov 19, 2007
Messages
34
Reaction score
0
Points
0
Age
36
Vehicle Year
1991
Make / Model
Ford
Transmission
Manual
yall are sending this stuff right over my head!!haha

my maf is the blow throught type! so is there any way i can use my stock one maybe if a get a burned chip!

and i want to run a bov!! but if i dont have to that would be great (save some dough)
 

V8RangerBoy

New Member
Joined
Dec 3, 2007
Messages
203
Reaction score
0
Points
0
Vehicle Year
1994
Make / Model
Ford
Transmission
Manual
I never really understood why people think it's some 'magical' thing. And BTW, the type of induction has nothing to do with an engine's (B)SFC. Most modern computer controlled engines are capable of getting into the .50-.55 range.
Those values are pulled straight from a tech article in a Mod Mustang magazine I have. You're 100% correct on most modern vehicles being able to get into the .5's, simply because of the computer's ability to constantly seek stoich 14.6-14.7. But (I just replied to that other post about why I have mine set so rich) because a more rich AFR is desirable at WOT for forced induction, (like I am set for, 11.5:1) this cuts the BSFC down from .5's to .6-.65 at WOT. Because a supercharger is usually more 'linear' and 'predictable' about the boost curve, you can get away with a more lean WOT mixture, hence why I referred to the .6 value for S/C'd applications. Under cruise, any engine will pull around .5 though, correct.
 

Dave R

New Member
Joined
Aug 6, 2007
Messages
658
Reaction score
2
Points
0
Location
In the snow belt
Vehicle Year
1953
Make / Model
Kaiser
Transmission
Manual
Well, unless there has been some revision in the laws of physics since I was at university, maximum power, regardless of induction type, is derived with an A/F ratio in the 12.5-13.3 range. Less than that and your loosing power and pissing fuel away.
 

Evil Ranger

New Member
Joined
Sep 7, 2007
Messages
30
Reaction score
0
Points
0
Vehicle Year
99 & 2000
Engine Size
4.2 & 4.6
Transmission
Automatic
Well, unless there has been some revision in the laws of physics since I was at university, maximum power, regardless of induction type, is derived with an A/F ratio in the 12.5-13.3 range. Less than that and your loosing power and pissing fuel away.
Maybe... but you are most likely pinging. That lean and you'll be losing power because you will have to pull so much timing. I'd stay at 11.7, or λ=.8 leaving enough cooling for slight fuel and weather changes and then you can keep the spark up to about 3° away from the spark knock limit.

For the amount of time you are at WOT the lower lambda wont make that much difference... a little bit of extra fuel can go a long way toward providing a knock safety margin for the occasional bad tank of gas.


Edit: Come to think of it look at the graphs from any of the LA3 and PK* computers... and the fuel switch... They really needed to keep it rich and fat. I mean given how sloppy the VAM was at determining how much air was going through them the AF on those cars at WOT was in the mid 10's.
 
Last edited:

Sponsored Ad


Sponsored Ad

Staff online

Today's birthdays

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top