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Which is better? Vortec heads or MPFI conversion

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BayouBlazer88, Feb 15, 2003.

  1. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    Just curious as to which one gives the most bang for the buck. If I went the Vortec route, it would be about 500 for the heads and 350 for the intake. If I went the MPFI route I would just get the conversion kit from Edelbrock or Holley which is about 930 and includes an intake and everything necessary. So the costs would be pretty much the same. I just wanted to know which puts out more additional horsepower and torque. Keep in mind my engine is an 88' 350tbi. Thanks.

    Matt
     
  2. the professor

    the professor 1/2 ton status

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    Tough one, just guessing..
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    You might call Edelbrock (good luck gettin through)--
    On a guess..
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    You already have the "latest heads" before the Vortec..torque and emissions are improved..
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    I think , on the face of it, that the 950CFM of the MPFI, along with the improved mixture and fuel distribution, would produce more power... /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  3. DesertDueler

    DesertDueler 1/2 ton status

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    A cam will give you more power for alot less. I would put a cam in it, and switch it to MPFI. If that isnt enough, then do the heads.

    Dan /forums/images/graemlins/burb.gif
     
  4. the professor

    the professor 1/2 ton status

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    If you go for a cam, make sure to use one recommended by Edelbrock or Holley...
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    The system you are talking about, is a Speed Density unit, which does not take radical cams or mods..
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    You are also looking at a CFM flow rate of 950+ or so, and the stock TBI only flows something lke 550-600CFM...a HUGE increase... /forums/images/graemlins/cool.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/thumb.gif
     
  5. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    A better cam is definitely on the "To do" list. In fact, I'll be replacing my cam with an Edelbrock cam the next time I work on my engine as well as a new timing chain, pushrods, and roller rockers. I had planned on changing to Holley's throttle body sometime in the future which flows 670cfm, not anywhere close to the MPFI's 950 but it's still better than stock. At first I had my heart set on the Vortec heads mainly because I had heard from other members that they are a 35-40 HP increase over stock heads whereas Edelbrock claims that their MPFI system provides only 25 more HP and 32 ft-lbs more torque. Then again Edelbrock's specs have been dyno tested. So I think I'm leaning more towards the MPFI now. Still got plenty of time to decide since I need to find the money first. Thanks for the input guys.

    Matt
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I'd say they are probably pretty evenly matched. The Vortecs allow you to play around a bit more (higher compression) without penalties, but the Vortecs and Injection are both farily expensive to retrofit.
     
  7. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    You say that the MPFI conversion is fairly expensive to retrofit. So if I went the Edelbrock MPFI route, what else would I have to buy or modify in order to complete the system? I thought all I needed was a higher flowing fuel pump.
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, lets see.

    Exhaust, gotta add an O2. Not a big deal, but still has to be done.

    Fuel pump, in-tank is expensive, esp. with a new sending unit at $300. External fuel pump is cheaper.

    Fuel lines. Maybe edelbrock is passenger side, and thus easier to run on a stock TBI truck. You can use the TBI lines, but at least on the camaro setup, you have to run the lines on the drivers side.

    VSS. Does the edelbrock use it (if not, forget that system) and if it does, is it extra $$, or is the wiring present, and just plugs into the existing VSS?

    EGR. How is it routed, is it even present?

    AIR/EVAP. How do they run it, if they even do?

    And just another thing off the top of my head, how does it all "plug in" to what you already have, or do you just tuck all of the stock wiring out of the way, and run Edelbrocks harness?
     
  9. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    Well I dont think I have to worry about the O2 since it's already equipped with one. The fuel pump is what I'm worried about, Edelbrock sells one just for this setup which is about $115, but I've never messed with the fuel pump or sending unit, so it will definitely be an experience. Fuel lines, I haven't clue, I'll just hope they fit and if not, hopefully Edelbrock will include everything to make them fit. VSS, I don't even know what that is. EGR valve, is mounted right on the front of the intake where it's much easier to access (Thanks Edelbrock), so no problems there. AIR, I pulled out the whole system anyway (take that EPA!). As for as everything else, I'll just hope that Edelbrock thought about the home mechanic when they designed the system and made it all fit nice and easy. If not, I'm a mechanical engineering major, I'll make it work. Thanks again for the info guys.

    Matt
     
  10. HarryH3

    HarryH3 1 ton status Author

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    </font><blockquote><font class="small">In reply to:</font><hr />
    You are also looking at a CFM flow rate of 950+ or so, and the stock TBI only flows something lke 550-600CFM...a HUGE increase...

    [/ QUOTE ]

    But the heads themselves won't flow that much, so the point is moot. Think about a funnel. Even of you make the mouth of the funnel wider, it still won't let any more fluid through the other end. The heads, valves, and cam profile determine the total amount of air that can actually move through the engine. Making a bigger hole on the intake side can't change that. If just opening up the intake made lots more power, then everyone would be running 1150 CFM Holley Dominator carbs on their small blocks. /forums/images/graemlins/shocked.gif
     
  11. HarryH3

    HarryH3 1 ton status Author

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    Look at any of Edelbrock's dyno tests with a critical eye. Many times their bold print will make some claim, like "35 extra HP". But when you read the fine print, you find out that not only did they install an MPFI setup for the test, but they also changed the cam. This makes it very difficult to determine if the MPFI actually made any of the difference, or if it would make a difference on a stock engine. Edelbrock is the MASTER of dyno-deception. /forums/images/graemlins/angryfire.gif

    Several years ago I installed their TBI intake, computer chip, TES headers, and a cat back system on my 4.3L powered S-Jimmy. After spending over $700 and wasting a weekend, 0-60 times were still 11.8 seconds, just as they were before all of that work. /forums/images/graemlins/mad.gif I called Edelbrock's tech line and they told me that I needed to bump up the timing 4 degrees and run premium fuel "to take full advantage of the upgrade". I'd bet that just doing that with all the stock stuff in place would have made a pretty nice difference, and saved me $700. /forums/images/graemlins/shocked.gif
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't count on anyone "taking care of you" because if you don't know what does what, you'll get crap like "VSS isn't needed" and "ground the Park/Neutral switch", and you'll have paid for it...

    EFI is fairly complex as a system (not as individual components) and if one way is "easier" than stock, it's also not likely to be as good. Sorry, but GM spent millions on R&amp;D for the injection systems, (and since TPI started in '85, you can tell how well the system holds up) a company like Edelbrock simply can't invest that in theirs.

    As Harry pointed out with the dyno tests, they are in the business to make money, and if they can sell you on an inferior product because you don't know any better, (I'm not saying their EFI *is* inferior, just that you won't know if it is if you've never had a properly made setup) then they win, and you lose.
     
  13. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    Well since you guys obviously know a lot more about engines than a 20yo shade-tree mechanic, which system would you go with if you were me? And after careful review of the MPFI system, it looks like the Vortec swap will be a lot cheaper and easier and maybe even better. So thanks for the help guys!

    Matt
     
  14. HarryH3

    HarryH3 1 ton status Author

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    Your biggest bang for the buck is to swap in a slightly hotter cam. Even with your stock heads, you'll be amazed at how much better the truck will run. /forums/images/graemlins/thumb.gif The cool part is that you can do it for under $200 if you do the work yourself. /forums/images/graemlins/thumb.gif Check with the major cam makers and see what they recommend for your particular rig. Their tech folks will want to know what tranny, gears, tire size, etc. that you're running.
     
  15. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    Any suggestions for cams? The only one I know of that will work with a tbi is the Edelbrock Cam. I'm sure there are others, I'll go to Jeg's right now and see what I can find.

    Matt
     
  16. HarryH3

    HarryH3 1 ton status Author

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    Don't just pick a cam out of a book. Call the tech lines and answer all of their questions. That will make it much easier to make sure you get the right cam. Check www.cranecams.com and www.compcams.com for starters.
     

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