Project "More Power" 406 SBC completed.

Discussion in 'High Performance Modifications' started by G72Zed, Apr 1, 2020.

  1. G72Zed

    G72Zed Veteran Member

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    Posting this here as it's for a customer of mine with a real nice true 1970 Z28, Hugger Orange, black stripe and interior with TKO600 and 12bolt w/4.10 with vintage TT II rims, a very nice ride to say the least.

    I have referenced this build on a few occasions in other "engine" post's so I thought I would share the results as some may find this interesting and/or informational if nothing else.

    This "400 SBC" engine was originally built at another shop a few years ago. The customer was never happy with it's performance, approx. 470 HP, not that bad, but he was never happy with it and wanted "More Power" (like most every other Hot Rodder LOL.) all the while staying with all the same parts.

    I set the CSA and ported the heads as per the CI and RPM required and got the CFM that was needed for the HP goal that was asked. Ported the intake,spacer and tuned the carb.

    My "Engine Master" and R&D machinist guru buddy did all of the critical machine work as it was not "straight" or up to his standards, he picked the HR cam based on the math/data that we had and reassembled the short block

    Quick Spec's:

    406(.77) SBC, 10.5 CR, pump gas, 243 @ .050, .600/.580 lift HR, 111 LSA. Ported DART 200cc (203cc) heads w/2.055-1.6 flowed 280 CFM @ 500-600 lift. Ported Super Vic 2925, HVH 1", tuned 750 Holley XP, NGK platinum plugs, DUI ignition, 34* timing.

    Needless to say, the customer is now very happy with "More Power" to the tune of almost 120 hp with the same basic engine. His fuel mileage will actually be better than before by almost 35% LOL.

    It's amazing what can be done with careful attention to detail, top quality machine work, and properly chosen parts based on experience and not advertising. To get 1.45 hp per cube, and more importantly 1.39 TQ per cube on pump gas out of these "small" DART 200cc straight plug heads says a few things for what these heads can do.

    Peak HP : 588 @ 6,200 to 6,300
    Peak TQ : 564 @ 4,600 to 4,900
    Peak spread: 1,600 rpm
    Peak VE%: 106.4
    Ave. AFR : 13.3
    Ave. BSFC : 0.41
    Peak SCFM : 701

    So in the end, everyone is very happy with the performance and outcome of this build project.

    SBC 406.png SBC 406 pic2.jpg
     
  2. jeff swisher

    jeff swisher Veteran Member

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    Very NICE!
     
  3. biker

    biker Veteran Member

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    Nicely done G, you can't really ask for more out of an all-round street engine. Looking forward to you getting my heads if I ever get let out of the arctic.
     
  4. G72Zed

    G72Zed Veteran Member

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    Thanks, the owner will have fun rowing that TKO now. Same here, but looks like we all may be in somewhat of a lockdown for a bit yet.
     
  5. Zstar

    Zstar Veteran Member

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    Well Done!
     
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  6. 1980RS

    1980RS Veteran Member

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    Nice, if that cam were on a 106° LCA it may have topped 600hp, bet the torque would go up.
     
  7. G72Zed

    G72Zed Veteran Member

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    Your right on that 1980RS, but in doing that it would of hurt other perimeters we were aiming for to the point it was decided to give up a few peak points was worth it. The goal was 575hp and was fully met anyway.

    The LSA is real combo specific as you are very much aware, and in this case it responded well to the LSA change. The owner has power brakes and the engine is already cranking 210 psi. This is an older client and the driving skills are what they are, not to be mean, but we were aiming for a flatter TQ curve and a nice wide TQ/HP RPM spread and the pump gas that we like is not always available in his area, hence the LSA going to 111 from 108.

    The other issue was the overlap % with the tighter LSA, the heads on the 1020 bench stated a few trends, but using the CFM data alone can lead you in the wrong direction. As I have mentioned before, you cant always judge a head on CFM alone, and this Dart 200cc head is better that how it looks on paper and that lead us to spreading the LSA, glad we did.
     
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  8. dcozzi

    dcozzi Veteran Member

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    With LSA, I like the idea of not sacrificing better usable RPM driveability for peak numbers.
    Those are some impressive numbers. Great job on getting maximum efficiency out of it.
     
  9. 1980RS

    1980RS Veteran Member

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    You are right about the heads, flow is only a part of the total package. I like to look at the Vortec heads as an example of a well thought out port design right out of the box. Does not need much work to make it even better and makes for a cheap fantastic street head. A lot of people will say a Dart head is crap out of the box, but so are a lot of other heads. Most heads are made to be ported, the AFR's that are CNC'ed out of the box are some of the best on the market and really don't need any other work. I have seen too many combos that guys buy the biggest port heads and the results are disappointing for them, they get discouraged then sell the stuff and build something else. A smaller port head is almost always superior on the street with great performance results. As for LSA most engines I have used at the track like tighter LCA's but on the street a wider LCA is the way to go.
     
  10. G72Zed

    G72Zed Veteran Member

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    Totally agree with you dcozzi. Thanks, the BSFC numbers are real nice. Used very little fuel during testing compared to some engine making 150HP less.
     

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