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Thread: Mid Output Intake Question

  1. #31
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    Yep, thats true. The thing to keep in mind however is that if you look at the flow numbers for unmodified Gt40 heads is that they pretty much level off at a little over .400" valve lift. It hardly improves from .400 to .500 and lifting the valve even past that becomes really pointless. So with the stock cam having roughly .444 valve lift using the stock 1.6 rocker ratio, its right where the flow starts leveling off.

    Honestly, I've always ported my own heads and intakes including more Ho and Gt40 heads then I care to recall way before I even considered swapping from an Ho cam to aftermarket. The low hanging fruit on the 5.0 are the cylinder heads and intake. Per dollar or per hour of labor, that is where the most impressive improvements to the entire powerband are to be had. The other benefit not often talked about is the reduced pumping losses and better fuel mileage that is attained with the improved efficiency.

    Ironically, this also allows more of the fuel to be redirected towards increased engine power instead of being wasted overcoming engine pumping losses, with the increase being better the higher the engine speed is.

    The stacking effect of gathering all these improvements together can result in an engine with the stock Ho cam that quite easily outpowers the engine with unported heads but with a performance cam. Not just at one rpm point but everywhere on the curve and by an embarrassingly noticeable amount when on the street or track.

  2. #32
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    Wouldn't let me add pictures in the PM so here's what I'll be sending you these are the injectors and computer I ran before I switched over to MAF. Also I had a Jet chip for this computer I'll send with it not sure it did anything performance wise but I have no use for it.

    Effect_20181105_072523.jpg
    Effect_20181105_072548.jpg
    Effect_20181105_072619.jpg

  3. #33
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  4. #34
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    Thanks again for the hookup, Outsidedog!

    Another questions for you guys regarding this swap. Do you guys generally leave the EGR system stock when doing this swap? If not, what do you need to change to keep things running smooth? I don't believe emissions will be an issue since I've had this car registered and inspected before and they gave me an emissions exempt sticker. If it helps to keep the system stock I will do that though.

  5. #35
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    When I did the swap from S.O. to H.O. I used a 70 mm bbk throttle body with egr spacer and left the egr on it and plugged in, actually passed emissions pretty easily too. Just retarded the timing and aired up the rear tires to 60 lbs.

  6. #36
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    Speaking of throttle bodies, I've been thinking a lot about which units to use here and I'd like to get ya'lls thoughts.

    A) Since I'm upgrading to a GT40 intake I'm imagining I have around a 70mm opening to work with. That said, if I take advantage of the opening size is it worth spending the money on an aftermarket throttle body/EGR spacer? I'm sure that acquire a stock explorer combo would be cheap but it looks like getting the linkage right and having to re-route the air intake tube due to the different orientation of this setup might be a pain in the ass.

    B) I could stick with a stock 87'-93' HO throttle body and EGR spacer for cost and simplicity sake. I've read that they bolt right up to the GT40 upper. Is this true and will I be sacrificing anything by using a stock 60mm size.

    I guess the general theme of my question is, for my build what throttle opening size is ideal? 60mm, 65, or 70mm?

  7. #37
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    There is no appreciable power gains to be had by anything larger than a 87-93 Mustang 60mm throttle body and Egr spacer at your engine's level of airflow.

    There is a place for larger throttle bodies but it simply isnt on near stock engines. Multiple independent dyno and track tests over the years have borne that out. Save your money for better, more effective mods and improvements.

    Just as an FYI, the explorer upper intakes that I have measured have a stock throttle body opening of 67-68mm. Ditto for the Cobra uppers that I have measured. The additional size is fine for use with a stock HO 60mm throttle body and Egr spacer.

    Vendors sell lots of throttle bodys for the same reason they sell a lot of cold air kits, its easy to bolt on and the customer convinces himself during the subsequent test drive that he realized a sizable power gain because he paid a couple hundred for it. Wouldve been better off throwin the $200 in a jar and putting some more with it each week or month to buy some good heads/intake and/or port work to same.

  8. #38
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    Sounds good to me! That's less money I have to spend, so I like it. I'll start searching around for a good deal on a stock HO throttle body and spacer now!

  9. #39
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    After you get it running what are your plans with it? Daily driver ? Any power adders or racing in it's future? Sorry if you already answered I didn't read back through the posts

  10. #40
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    If you're adding GT40 heads and a HO cam to a stock 86-88 short block be sure to check piston to valve clearance. Better to know if you need to cut some piston valve reliefs than finding out when you bend all the valves the first time you rotate the engine over .
    '88 Thunderbird LX: 306, Edelbrock Performer heads, Comp 266HR cam, Edelbrock Performer RPM intake, Edelbrock 70mm TB, 76mm C&L MAF, 30lb injectors, 2.5" exhaust, AOD with 2800 PI converter, 8.8 with 3.73 gears, 31 spline Traction-Lok, 31 spline Moser axles, 04 Cobra front arms, Maximum Motorsports extreme duty rear arms, subframes.
    '11 Focus, '12 Mustang 3.7, '17 Accord EX-L V6

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