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  1. #1

    Default injector size for this engine combo

    I am planning on doing
    a 331stroker 9:1 compression with trick flow 170 heads and performer 5.0 intake. Both have been extrude hone
    and a v3 supercharger and probably limit it to 6lb pulley. What size injectors and which mass air meter?

    my other thought is doing a 331 with 10.5 or so compression and no supercharger. I am thinking 30lb injectors would be okay with this combo?

    I donít have any real cam choices yet so any thoughts on good streetable cams would help
    I would like to have something mid 11 capable 120mph or so

    thanks

    todd

  2. #2
    FEP Power Member Ourobos's Avatar
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    You're tuning it I'd hope? I'd throw 42# in there for future growth if so. I would also look at a 90mm lightning meter or the likes as well. If you're NOT tuning it.. you're making a mistake LOL
    1986 CHP SSP Coupe

  3. #3

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    Yes, but I was thinking with a pro m meter. Or would I need someone to match the Lightning with a chip?

  4. #4
    FEP Super Member cb84capri's Avatar
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    Since they are aluminum heads, you may want to shoot for more compression. I would likely go 11:1 na and see what vortech reccomends if you plan to supercharge it. A stroker with a supercharger, you should plan your engine build around a dart block.

    Cale

  5. #5

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    You don’t need boost or a stroker to dip into the 11’s with a foxbody. High compression N/A combo with the right stuff will go low 11’s. Especially with proper weight reduction.

    +1 on dart block

    Many say 500HP is about the limit for a stock block. Twin turbos will blow right past that on a Stock head motor.

    There are fringe cases of making lots more but they are a time bomb.

  6. #6
    FEP Power Member Ourobos's Avatar
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    A calibrated meter might let you start it up and drive it around the block, but any jump in size that significant needs to be tuned to last any amount of time.
    1986 CHP SSP Coupe

  7. #7

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    I'd get 60# injectors. Room to grow in the future, and they are a common size now, priced reasonably. Buy once cry once.

    Jess
    Previously owned;
    1979 Mustang, v6 swapped to EFI 393, custom installed m122 blower, 4r70w trans, Megasquirt II, T-top swaped in.
    1990 Mustang, 545 BBF, C-4 with brake, ladder bars.
    1983 Mustang, 1984 SVO Mustang
    1984 Mustang convertible, v6 swapped to 351
    1986 Mustang GT, 1989 Mustang GT convertible
    1992 Mustang coupe, 4 swapped to 302

  8. #8

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    I am pretty confident at this point that "Internet tuning" is actually not really a thing. It sounds like you have no plan. The first thing you need to do is decide what your budget is. The second thing is to decide what you want to use the car for and what your expectations for it are. There is no "best cam" or "injector size" that fits all engines. Once you have an actual plan and decide on the actual parts required to accomplish it, we can help with injector size but it would be better to ask the guy that is doing the tune (you ARE doing a tune, right?) and I would recommend going on their advice.

  9. #9

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    I know what I want to use the car for, I do know my budget,
    I don't know if I want to supercharge or go high compression stroker.
    I do know the cam choices are different for both applications and maybe some MAF's are better NA vs supercharged

    Part of my plan is getting input from anyone who has experience with their parts and combinations, If you had a cam and it worked well I would like to know, if your MAF is great let me know.

    Prior to this build I had a stock 302 bottom with powerdyne and edelbrock heads ported lower and upper, ran a couple different MAF's c&l pro m, multiple injectors sizes with fmu. No tune or chip for 50K miles it ran 12.0 @ 115 in an 86 vert lx,

    So tuners, I don't know who is good or isn't,

    Thanks

    Todd

  10. #10
    FEP Power Member Ourobos's Avatar
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    I've had everything from stock 302s to 418w strokers with a 250 shot, to turbo and supercharged strokers. What's the plan, drag car, street car, mix of both? To me nothing beats the sound and power of a big cube 351w based stroker. And if needed, throw a power adder on top of it. For the cost now days, you may as well get a custom cam, $350 pretty much.
    1986 CHP SSP Coupe

  11. #11

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    80% street, then capable of autocross and drag or any other form of road racing. Doing coil overs front. torque arm Maximum Motorsports full suspension set up basically arriving tomorrow
    with cobra brake conversion sitting in garage. I am hoping to get it to handle close to my 16 gt 350, but faster
    that is why I keep leaning Stroker motor for the durability.

    interior is missing so a real blank canvas there. Paint I have no idea yet
    I want to keep it light but not race car light it will have a stereo

  12. #12

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    Oops, I guess 400 or more to the rear wheels and somewhat driveable around town

  13. #13
    FEP Power Member Ourobos's Avatar
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    A built 351w-418w will make 500+ at the tires..
    1986 CHP SSP Coupe

  14. #14

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    To add some punctuation to the above sentences.............

    There are several AFR185 head 408 stroker builds featured in magazines with various intakes and cams and power output in the 600-675HP range. What it would make depends upon a LOT of factors, but thats a LOT of power for a street car.

    Similarly, several build show stock rotating assembly 302 HO's with 1.7:1 rockers, heads like the 165 renegades or the 185's making right at 400HP and 400 Lbs.

    Mileage on actually getting there, or course, always varies. You can mess up and go too tight on main bearings and easily give up 40-50 HP on a SBF, for example.

    Then there is crank HP vs rear wheel when considering injector sizing. Injectors could give a ratt's butt what is behind the motor-- focus on output at the crank!

    There are formulas for calculating injector size requirements based upon power output and fuel pressure. For example, a 19lb injector is at maximum duty cycle at 320HP. Ever wonder why so many builds that don't bother to change injectors end up leaning out and jacking up fuel pressure and struggling to get past 350HP? Bingo!

    24lb injectors are good to about 400 HP if memory serves.

    There there is the fuel discussion. Race gas? Premium? Pump gas? E85? Each have their advantages and disadvantages. Big thing is E85 takes around 35% more fuel but usually yields around 12-15% more power than premium fuel.

    Now I'll state the obvious one more time regarding "tuned" or "recalibrated" MAF meters. They are not tuned or recalibrated-- they are broken! Don't use them unless you WANT your EEC-IV pulling a crap-load of timing out of the motor on you and giving up nearly all the HP gains your high end parts provided in the first place.

    If I had a nickel for every over priced build with recalibrated or mistuned this/that...... after my stock appearing carefully tweaked 86GT dragged their butts down the 1320, I'd have a starter fund for a dream supercar. I'm sure others can name off some similar experiences too. Granted, not everyone can drive a stick car without seeing how much rubber they can leave coming out of the hole, but those who can enjoy the view in their rear-view mirror.

    Start the refresh on a 4-eye by refreshing and upgrading the tail lights and eliminating the rust in the hatch. Its not like they'll see much else anyway. Lol.

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