TCCoA Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
1,181 Posts
Discussion Starter #1
So I have driven 4 different N/A 3.8l Tbird/Cougars ranging from 93-96 and I have noticed they run better at 85-90% throttle vs. WOT , or am I just crazy? If I am not crazy could it be that the stock exhaust / Air intake is too restricting even for stock applications and/or the stock 14# injectors are not enough and a stock N/A 3.8l could use 19# with ease, Any opinions on this?:confused:
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,517 Posts
IIRC the PCM considers anything above about 60-70% throttle to be WOT. As far as I know, that would mean the PCM isn't doing anything differently with regards to engine management at 80-90% throttle than it is at 100%.
 

·
Registered
Joined
·
1,647 Posts
IIRC the PCM considers anything above about 60-70% throttle to be WOT. As far as I know, that would mean the PCM isn't doing anything differently with regards to engine management at 80-90% throttle than it is at 100%.
This is true. Mine only goes to 92% anyway and that's definitely WOT.
 

·
Premium Member
Joined
·
5,862 Posts
IIRC the PCM considers anything above about 60-70% throttle to be WOT. As far as I know, that would mean the PCM isn't doing anything differently with regards to engine management at 80-90% throttle than it is at 100%.
If that's the case, then the reason the car feels like it's pulling more at 80% then 100% is it's running richer (since there is less air). My car seems to run the same way - usually I accelerate with my foot almost floored just for that reason.
 

·
Registered
Joined
·
1,181 Posts
Discussion Starter #6
Well I figured I wasn't crazy ( no more than normal ) anyway so it seems to me that a stock N/A 3.8l could run perfectly well with 19# injectors, 14# just seems to small. My 89 Ranger had 19# injectors before I put the SVO turbo motor in it. They had the the same part numbers as my buddies 89 GT. Also a GM 3.8l in a 95-99 Camaro has 19# and a 90-92 4.0l Ranger has 21#. I think 232 CID is to small for 14#.
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,517 Posts
The general formula for the maximum power an injector can support is injector size times percent max. duty cycle (usually .8) divided by the brake specific fuel consumption (usually about .5 on a n/a engine) times the number of cylinders. BSFC is the number of pounds of fuel per horsepower produced.

In this case it's 14 * .8 / .5 = 22.4 HP per injector x 6 cylinders = 135 HP. Granted the BSFC figure of .5 is most likely not the BSFC of this engine (obviously it's not, otherwise all N/A 3.8s would be running drastically lean at WOT), but I definitely agree that the 14s are probably close to their limit on a N/A 3.8.
 

·
Registered
Joined
·
613 Posts
So.. who's gonna come up with the mod regimen for swapping in 19# injectors?

I noticed the same thing but figgered it was probably saving me money. I know the 3.8 gives me all the 'get out of the way' power I *need* on low end, lacks a little for high speed merge on city freeway on-ramps. The kind where you have to move over 3 lanes in traffic within 1/2 mile.
 

·
Registered
Joined
·
1,181 Posts
Discussion Starter #10
Well I think I going to do some experiments with this . I found that 96/97 crown vics have orange top 19#'ers and they will plug in and fit the fuel rail. Also may try to use the pressure regulator and maybe the MAF. Opinions are welcome. I just feel like there is more in this motor that can be released then maybe a cam change and some intake and head work
 

·
Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
Joined
·
9,517 Posts
You'll need a tune to go with the injectors; also keep in mind it won't be a "fair" comparison to stock unless the only thing adjusted in the tune is the fuel delivery table.
 

·
Registered
Joined
·
1,181 Posts
Discussion Starter #12
Yes I was planning on a tune . I'm not trying to build a fast car with this one I just think some simple mods would improve the 3.8 and as for the cam change not much over stock maybe just a SC cam. This is my daily driver and I show it sometimes, later on I'll be looking for another bird or cougar to build I have several SBF back home in TN just sitting .
 
1 - 12 of 12 Posts
Top