Whats wrong with this build...
+ Reply to Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 14 of 31

Thread:
Whats wrong with this build...

  1. #1
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default Whats wrong with this build...

    So Ive put about 30 hours on my new 408sbc... Im not feeling what the builder promised me...

    heres the build

    400 sbc .40 over = 408
    Profiler aluminum 195cc/64cc
    nx262 comp cam
    9.3 cr
    RPM performer edel intake
    edelbrock 750
    Stock thunderbolt VI
    Stock fuel pump
    GLM aluminum manifolds with imco stainless risers.
    Alpha SS outdrive
    Claimed to have 425-475 hp
    Timing set at 10* idel and 35* at 4k

    4900rpm at 63mph with 23p tempest

    So theres the build i have and Im just not feeling the power it should for my Powerplay 185. For this power I should be going 70 easy.... Dont get me wrong there is plenty of crazy torque at 2k-4900k but then it just dies off.

    Can anyone point anything out?
    Last edited by chrisf695; 07-23-2013 at 06:37 PM.

  2. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  3. #2
    Senior Member OLD MAN ON THE LAKE's Avatar
    Join Date
    Dec 2007
    Location
    Phoenix
    Posts
    786

    Default

    Try a Revolution 21

  4. #3
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    the nitrous cam isn't helping your cause any.
    The GLM manifolds are not much more than aluminum versions of the stock Mercruiser exhaust.

    It would appear that you are probably running out of cam, manifold and carb, at that engine size and you have a cork stuffed in its ass to boot. Can't get the new air in if the old air in still in the cylinder.
    This thing have thru the transom exhaust, or is it thru the prop?



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3
    Last edited by gn7; 07-23-2013 at 06:43 PM.

  5. Remove Advertisements
    PerformanceBoats.com
    Advertisements
     

  6. #4
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default

    Quote Originally Posted by OLD MAN ON THE LAKE View Post
    Try a Revolution 21
    I rented a 23p rev 4 3 weeks ago and got 4800 rpm at 61mph. It got me right on plane very quickly and plenty of torque in the same rpm range as the tempest. But way too much stern lift... wanted to lift the back up and point the nose down to the port side. scary at times...

  7. #5
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default

    Quote Originally Posted by gn7 View Post
    the nitrous cam isn't helping your cause any.
    The GLM manifolds are not much more than aluminum versions of the stock Mercruiser exhaust.
    Why would he have chosen the nx262? I think he said it was like in the middle of the xm262 -270 cam... but hell he could be wrong...

    So should I be looking for some Stainless Marine exhaust instead? would this add the performace i need?

    It has thr hull exhaust.
    Last edited by chrisf695; 07-23-2013 at 06:46 PM.

  8. #6
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default

    Click image for larger version. 

Name:	2013-06-30_12-30-44_931.jpg 
Views:	89 
Size:	28.2 KB 
ID:	337281
    Click image for larger version. 

Name:	20130519_131618.jpg 
Views:	97 
Size:	22.8 KB 
ID:	337289

  9. #7
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by chrisf695 View Post
    Why would he have chosen the nx262? I think he said it was like in the middle of the xm262 -270 cam... but hell he could be wrong...

    So should I be looking for some Stainless Marine exhaust instead? would this add the performace i need?

    It has thr hull exhaust.
    Any of the better aftermarket aluminum manifolds are better. I think the EMI's probably has the best SBC manifolds. But Stainless Marines are better than the GLM "replacement" manifolds.

    The NX cam has way more intake/exhaust split than the either of the XM cams. The NX 262 has 18* of split and the XM 262 and 276 have 6*. Plus the NX cam has 1* additional LSA which you don't really need for you application either. Put a 150HP spray system on it or a blower and it will wake up. The exhaust manifolds will still get in the way, but you feel a difference

    The manifold is on the low side of sufficient for an engine that size. The Performer RPM probably would have been a better choice. You might gain a little with a 1" open spacer because the Performer doesn't have the cut down center divider of the RPM. The spacer may steal a little low end torque, but I doubt you would notice.

    The Edelbrock 750 isn't helping you much either. Not as much of a problem some of the other stuff, but I think a Holley would gain you a little.
    Keep in mind, just because its small in size, that thing is only 46 inches from being a 454 BBC. It wants to be fed like a BBC



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3
    Last edited by gn7; 07-23-2013 at 07:24 PM.

  10. #8
    Senior Member ol guy's Avatar
    Join Date
    Mar 2008
    Location
    Lake Elsinore Ca
    Posts
    3,814

    Default

    Quote Originally Posted by chrisf695 View Post
    So Ive put about 30 hours on my new 408sbc... Im not feeling what the builder promised me...

    heres the build

    400 sbc .40 over = 408
    Profiler aluminum 195cc/64cc
    nx262 comp cam
    9.3 cr
    RPM performer edel intake
    edelbrock 750
    Stock thunderbolt VI
    Stock fuel pump
    GLM aluminum manifolds with imco stainless risers.
    Alpha SS outdrive
    Claimed to have 425-475 hp
    Timing set at 10* idel and 35* at 4k

    4900rpm at 63mph with 23p tempest

    So theres the build i have and Im just not feeling the power it should for my Powerplay 185. For this power I should be going 70 easy.... Dont get me wrong there is plenty of crazy torque at 2k-4900k but then it just dies off.

    Can anyone point anything out?
    you answered your'e own question and GN-7 elaborated! Its starving to death with that carb! In other words when you say it runs hard on the bottom then dies off "IT's STARVING FOR FOOD TO PULL ON THE TOP" JMO

  11. #9
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default

    Quote Originally Posted by ol guy View Post
    you answered your'e own question and GN-7 elaborated! Its starving to death with that carb! In other words when you say it runs hard on the bottom then dies off "IT's STARVING FOR FOOD TO PULL ON THE TOP" JMO

    What size carb should I look at? Edel/holly 850?? I'll order it tomorrow!

    The intake is the rpm performer intake... Should I also upgrade the fuel pump?

    the cam is something ill have to wait til winter... But I would like to gain as much s I can right now with other things...

    Thanks for all the quick responses!

  12. #10
    gn7
    gn7 is offline
    Senior Member gn7's Avatar
    Join Date
    Jan 2008
    Posts
    25,975

    Default

    Quote Originally Posted by chrisf695 View Post
    What size carb should I look at? Edel/holly 850?? I'll order it tomorrow!

    The intake is the rpm performer intake... Should I also upgrade the fuel pump?

    the cam is something ill have to wait til winter... But I would like to gain as much s I can right now with other things...

    Thanks for all the quick responses!
    A fuel pump won't give you anything unless its running out of fuel at WOT. Might try a fuel pressure gauge to verify. But I doubt that's the issue here. Not sure a 850 holley will help much because the exhaust is choking it up. Might help a little.

    The cam, exhaust and carb are main problems I see. Probably in that order as well.
    Sorry, its just not a good combination of parts.



    100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3

  13. #11
    Senior Member ol guy's Avatar
    Join Date
    Mar 2008
    Location
    Lake Elsinore Ca
    Posts
    3,814

    Default

    Quote Originally Posted by chrisf695 View Post
    What size carb should I look at? Edel/holly 850?? I'll order it tomorrow!

    The intake is the rpm performer intake... Should I also upgrade the fuel pump?

    the cam is something ill have to wait til winter... But I would like to gain as much s I can right now with other things...

    Thanks for all the quick responses!
    My opinion would be a 4780 holley and a fuel pressure gauge to make sure it is getting enough fuel with whatever carb! Also keep in mind you are moving a rather heavy boat and 70 MPH might be a push! No offense but you need to keep thimgs in perspective! Also looking at the wheel you are spinning you may want to back down just a pinch on the bight of the wheel (prop). If it leaves great and lays down think about if you could give up alittle on the bottom to pick up some on the top?

  14. #12
    Senior Member stoker2001's Avatar
    Join Date
    Dec 2007
    Location
    Folsom,Ca
    Posts
    1,713

    Default

    GN7 pretty much said it all
    195cc pretty small for 408 IMO
    Eddy perf RPM intake...REALLY
    750 CFM is small IMO
    need some real exhaust
    shelf cams suck,with right valve events you could run 11to1 Comp on 91 octane
    Whacker Smacker M/E #561 IHBA "first looser"champ 2006&2007&Sportsman Driver of the Year

  15. #13
    Junior Member
    Join Date
    Mar 2013
    Posts
    28

    Default

    Thank you for all the responses guys, I appreciate the honesty! I guess Ill just start looking for a holley 800cfm and exhaust.... Cam will have to be done over winter. I just have to enjoy what I have now for the rest of the summer. I mean 63mph is still pretty fast and I am still playing with props... I will be trying a 25p mirage plus this weekend and see how it goes.

    It just really SUCKS that I had this motor built trusting this guy. Hes a well known builder in our area... but I dont think he does too many performance engines. What kills me is the cam choice... WTF was he thinking!?!? Pisses me off. I know computers... thats what I do... IT... and when I build a server I do it right. I dont know engines like he did and when money has nothing to do with it and you screw it up... WTF...

    So... a re-cap

    XM262-270 cam
    Holley 800cfm
    EMI/ Stainless exhaust

    I throw this into the mix... hers my desktop dyno with flow numbers of the heads... any input on this would be great also.
    Click image for larger version. 

Name:	dyno408.jpg 
Views:	100 
Size:	19.7 KB 
ID:	337649
    Click image for larger version. 

Name:	flownumbersheads.jpg 
Views:	84 
Size:	11.2 KB 
ID:	337657
    Click image for larger version. 

Name:	408sbcdyno.jpg 
Views:	85 
Size:	20.4 KB 
ID:	337665
    Last edited by chrisf695; 07-24-2013 at 06:16 AM.

  16. #14
    Senior Member sammyc57's Avatar
    Join Date
    Sep 2010
    Location
    Broken Bow,OK
    Posts
    656

    Default

    That intake sucks for a true hotrod.

+ Reply to Thread
Page 1 of 3 1 2 3 LastLast

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Please select your insurance company (Optional)

Log-in

Tags for this Thread

Digg This Thread

Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •  
 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95