How big of mass air and throttle body for a built 351?

[SpareParts]

I did the EFI conversion last spring, I used some parts that I had already had. Bottom line, I know the upper intake is from a speed density Crown Vic. The intake port was only 52mm? That's what my conversion measurement came up with at least. The lower is a 351 truck lower that I have ported and gasket matched to the stock 80's-90's intake gasket with a BC adapter. You can hear the exhaust change tone about 3000 rpm and kinda sounds constipated! I assume that it is caused by the restriction in the upper intake and small throttle body.

The short block is a 30 over, fully balanced and ARP'ed with 9.5:1 pistons. It has a custom ground cam that is 204/210 duration with 460/480 lift, 110 deg. lobe sep. The heads are 72' Torino heads the have been ported heavily and gasket matched to the 72' big intake gaskets. I never flowbenched them but I know the do flow well.

The intake set-up I'm planning on is the Edelbrock Performer "already have" with a ported Typhoon lower. I just don't know how big of throttle body and mass air meter/injectors I should run.

The motor is set up for and has great torque but dies on the upper end. Currently I'm currently running the 19lbs. injectors, stock mustang mass air with a A9P computer and 92' harness.

Sorry for so much info at once!

Thanks in advance,
David

 

[73azbronco]

Have you talked to a tuner in your area yet? My best advice is to seek out one and have a chat.

My research shows a 351 running out of injector/computer around 3-4000RPM. Anything more than that and you hit 100% duty cycle, 24lb would be best for a truck that is modified like yours, you need to have the computer tuned for your setup. Most important, ensure the injectors/MAF and TB all work together.

One point, while hi horsepwoer maybe a cool thing, the size of TB needed could result in no driveability at low RPM, in other words, you touch the throttle and the motor winds up because it has a larger than needed TB for the desired throttle movement (this issue can be corrected by changing throttle movement).

 

[SpareParts]

I haven't looked real hard for a tuner in this area but I have never heard of any and I have been into motorsports for close to 20 years around here.

I'm not looking for the biggest, I want the system to work right. I have read a lot of threads and searched a bunch. Most come up with dead ended conversation and no one sayin the results. Crawling and the throttle tip in is a concern, I have a lot of control now. I don't want to loose torque and the control I have with my current set up but would like to let it breath better.

I should have said that I also have shorty headers with (2) 2 1/2" pipes going into a Magnaflow muffler that exits through a 3" tailpipe.

 

[Nightstick]

Shameless plug... I never ran my EFI (decided to go propane), but if what you come up with tells you to get a 75mm TB and 76mm MAF I one of each to sell ya if you're interested. They're both new.

 

[Monster Mike]

im going to keep an eye on this thread. i am just now gathering my efi parts and im going to start with a 65mm TB from a 99 explorer and 24lb injectors and a A9P computer. Ryan at RJM told me ill have to find an aftermarket maf sensor to bring it all together. or another guy I know who races only EFI 302's said i can use the TB and MAF from a 94 GT with what i have.

Im running edelbrock performer heads, lightning lower, explorer upper and the RJM harness so Im not sure if were comparing apples to apples since im still learning.

Goodluck!

 

[ransil]

You can guess all you want at what might work, but a dyno tune will tell you exactly what you need and where you need it.

 

[ken75ranger]

Contact rjlougee. He has done the setup you're looking to do. He really knows his way around moded Ford EFI.

 

[gravy]

76 mass air and 70 TB with 24lbs injectors is a good set up for your motor as long as you can free up the intake flow- which you have with that intake. A adjustable fuel pressure regulator is needed along with a tune to get it dialed in but it should run pretty good with out the tune. I run this on my 5.0 with gt40 upper and lower, B cam and stock internals- no tune and runs good. BBK 76 Mass Air and Proffesional Products 70mm TB. Dave

 

[BroncoinAlaska]

76 mass air and 70 TB with 24lbs injectors is a good set up for your motor as long as you can free up the intake flow- which you have with that intake. A adjustable fuel pressure regulator is needed along with a tune to get it dialed in but it should run pretty good with out the tune. I run this on my 5.0 with gt40 upper and lower, B cam and stock internals- no tune and runs good. BBK 76 Mass Air and Proffesional Products 70mm TB. Dave

This is what I have been told for my 347 EFI. I have FMS 24lbs injectors, BBK 70mm TB, 70mm Ford F2VF 70 mm MAF (SN95 MAF). Bronco runs and has power but seems like a tune could really help. I still need an adjustable fuel pressure regulator. I am also thinking I need a different MAF but I have heard a ton of different opinions and am having a a hard time choosing the best MAF for my application.
Also make sure if you are running a cone filter it is longer than 7 inches. I had a shorter one one initially and the engine was starving for air flow.

 

[73azbronco]

While it may initialy run OK without a tune, long term you may be running lean or rich and why not spend the dime to get it all dialed in early rather than later.

 

[SpareParts]

I guess I need to look for a Tuner in my area! I know I'll have to change the intake, TB, MA and injectors before they set up a tune for it.