HP and TQ estimates on 340 build?

Mopar Racers Forum

  1. kanders

    kanders Well-Known Member

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    Well I'm still stressing out about which 5 spd to put in the 71 Duster and torque specs always come into the picture. Problem is that I have no idea how much HP or TQ this engine will make so if any of you racers or engine builders care to make an educated guess, have ater. This engine was built a number of years ago but has never been run so it's good stuff but old school technology. The specs off the build sheet are:
    1969 340 block bored .030
    Stock rods and crank, rods polished and SPS bolts
    1971 915 J heads, 2.02 intake 1.6 exh will port match to intake
    Double or triple? valve springs seat press 145 open press 310
    Engle hyd cam, int 515 lift 278 dur / exh 535 lift 286 dur
    Milodon cam gear drive (does anyone use these anymore?)
    Forged pistons, final comp ratio 10.7:1 with felpro blue gaskets
    Milodon 9 QT oil pan w/windage tray
    Holley strip dominator intake or old style Torquer (probably use Holley)
    Holley 750 DP carb
    Hooker comp 1 5/8 headers
    MSD 6 ign box w/mopar dist
    2 1/2" exhaust
    No ignition wires yet, do you think the yellow or orange ones make more HP? (just kidding, wanted to see if you,re paying attention)
    Everybody knows the yellow ones make more HP!
    For me, the cam is the big question mark. When this engine was built I think the high RPM long duration lumpety lump thing was big but I'm no engine builder. Tell me what you think, Kev
     
  2. crackedback

    crackedback FABO Gold Member FABO Gold Member

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    I'd guess 380-390 if everything is right.
     
  3. Toluene56

    Toluene56 Well-Known Member

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    with stock flowing J heads and without the correct cam timing. I would say perfect world about 410hp 400tq ....

    but really the previous post is more like it... lol nothings perfect.

    It are has potentialz..:supz:
     
  4. kanders

    kanders Well-Known Member

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    So according to the first 2 responses, the horsepower and the torque would be roughly the same? Acording to those numbers, a transmission rated for 450ft lbs of torque should be adequate so long as I don't go too aggressive on the clutch.... right? Kev
     
  5. kanders

    kanders Well-Known Member

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    Anyone others?
     
  6. Toluene56

    Toluene56 Well-Known Member

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    I think you'll be ok.
     
  7. dgc333

    dgc333 Well-Known Member

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    I am going to buck the above estimates. I have a 360 that has the same compression better flowing magnum heads and what is about one size smaller cam that is a modern fast ramp. My engine makes 370 hp based on quarter mile trap speeds. The 340 is giving up 20 cubes so I would guess 350 hp and high 300's for torque.
     
  8. kanders

    kanders Well-Known Member

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    What kind of times are you running in the 1/4? Kev
     
  9. 7172 duster

    7172 duster 7172 duster Legendary Member

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    [​IMG][/IMG]


    [​IMG]
     
  10. dgc333

    dgc333 Well-Known Member

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    The best 1/4 is 13.7 @ 102 mph. My propblem is traction my 60' times stink, the 13.7 run was had a 2.2 sec 60'. Getting the chassis sorted out for sub 2 second 60' times will get me very close to 12 seconds. Those times were also with a smallish 600 cfm carb.
     
  11. inkjunkie

    inkjunkie Well-Known Member

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    i do not think either one of the current 5 speeds is that good of a solutuion. i know there is a few members here that have a tko600 and like them, but for as many good things you hear about them you hear a like amount of bad. and the t-5, well, unless you plan on going with a full bore aftermarket one they just are not all that strong. how much of a hurry are you in? McLeod is claiming, at least last I read, that there unit will be out by the end of the year. granted, it does not look like it will be a true bolt in, but at least it gives you another option.
     
  12. mshred

    mshred The Green Manalishi

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    remember that its not just torque that kills a transmission...The weight of the car, what rear end gear you are using (stickshifts LOVE high numerical ratio ring and pinions), what tire your on, what clutch you use, etc....just remember there are guys with low 12 sec b-body's breaking stock tko600's, just like there are guys breaking stock t5's in low 12 sec mustangs...if you plan to run anything mid 11's or faster, id look at a built 18 spline 833, nash, richmond, or jerico box with a good adjustable clutch....or you can wait for the Mcleod box, though i dont have high hopes for it anymore, and would rather let others be the guinea pigs for it before i buy one myself
     
  13. kanders

    kanders Well-Known Member

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    7172 Duster, thanks for the dyno results. I think that it would be a close comparison. You have 20 more cubes but less compression and smaller intake valves, maybe not too far off those numbers.

    dgc333, are you running drag slicks or street tires? I'm running a 750 DP, should help with my setup.

    Inkjunkie, I have been speaking to anybody I can about pros and cons of all the 5 speeds and have gotten alot of insight and different opinions. I've talked to people at Astro, G force, American Powertrain, Liberty's Gears, and Promotion Performance. I won't say who said what but some have seen the internals (gears)from the Mcleod prototype at SEMA(I think) and don't feel that trans will hold up to the torque specs they are claiming, but then again they are the competition. Either way I want to be driving the car before then and don't think I'd be prepared to be a field tester for it.

    mshred, I could be wrong and maybe someone with more tech experience could chime in here but wouldn't a 2900 lb fox bodied mustang running 10 seconds be transmitting as much torque to the pavement as a 3400 lb Duster running mid or high 11's? An 833 4 speed is not an option for me since I will be using the car for 1/4 mile as well as 200 or 300 mile trips to car events in southern Alberta and neighboring provinces of Saskatchewan and BC, and with 4:30 gears that won't work so gooder. You are correct about the strength of the 833, I talked at length with a guy at the Portland swap meet this spring who always has a lot of Ford and Chevy rebuilt units at the meet for sale and he said the reason he doesn't do alot of 833's because they are so tough and don't break as often as the others. Kev
     
  14. mshred

    mshred The Green Manalishi

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    Kevin, a 2900lb mustang running 10's will not be transmitting as much torque as your 3400lb duster running 11's...It takes less power to propel a lighter car than it does a heavier car, so that mustang running 10's may only need 500hp but for your 3400lb duster to run 11's it may need the same amount of power (hypothetically, im not saying this is how much power it takes). On top of the power is also the weight of the car which takes a toll on the drivetrain since its more weight to get moving, as well as the way it is geared, how you drive it, what clutch, etc. When your talking racing a stickshift there are so many factors to keep in mind for tranny survival.

    Also remember that when you talk to people at certain companies, they are trying to sell you a product. You even said it yourself about the competition and some opinions on the Mcleod tranny (im on the fence with that thing as well). When you call a company to ask them about their stuff, unless they are genuinely thinking it is WAY out of place in your setup, they will do whatever they can to sell you their product..however, i have talked to astro, g-force, and liberty myself all about t5 stuff, and they all said something along the lines of "you are taking a chance with the t5, a stronger transmission would be better for your setup, therefore we can't gurantee you anything since everyone has different results with these transmissions"...This was expert opinion from the makers of the product, which tells you the variedness of expereinces with these trannsmissions and their reluctance to gurantee anything on these transmissions

    the opinions you should be after is not those of the companies and all the options they are touting, but of the guys on the ground- all the racers and drivers who have used these products and flogged them, whether they be on the street or strip...you need to find out from them how fast (or slow) the car went, and with what setup (i.e. clutch, shifter, gear, car weight, tire...these are all KEY factors to making t5's live btw, just ask anyone who races them) to get an idea of whether it will work in your situation...check out some mustang forums or racer forums i.e. yellowbullet, nmra forums, umtr stickshift forums...just do a search on there and you will see the wealth of info and just how touchy the t5's are...i cant tell you how many guys i have pm'ed, how many questions i have asked, and how many mustang guys locally (I have TONS around here) that i have talked to about this...i get varied opinons, and the only way i'll know is once i do it myself...but from general consensus, i already have an idea of where the t5 will go once i lay down on it

    good luck!
     
  15. kanders

    kanders Well-Known Member

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    mshred, I did go on yellowbullet as you suggested last time and found some info but maybe I'm not lookin in the right place. Sounds like a lot of guys running stock T-5's in fast cars and had good luck with them. Also saw a lot of trash talk and bad language(sure aint FABO), and what's with porn on a racing site(ok maybe I'm not complaining about that part LOL). The one thing that everybody agrees on with the T-5 is that the biggest killer is using a clutch that's too aggressive. I think I'm ordering a Promotion T-5 tomorrow. Kev
     
  16. dgc333

    dgc333 Well-Known Member

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    BFG Radial T/A all season street tires. A 750 DP may ad a few HP but it won't make a huge differnce. I have had 600, 670, 725 and 750 cfm carbs on my engine and there is very little difference by the butt dyno and none between the 670, 725 and 750 carbs, I settled on the 670 because it has a very noticable improvement in driveability over the 725 and 750 without giving up anything on the top end.
     
  17. mshred

    mshred The Green Manalishi

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    LOL...you decided that fat that your going promotion? either way good luck man
     
  18. kanders

    kanders Well-Known Member

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    I decided that ....FAT? LOL I guess you meant fast and no it wasn't fast, I've been laboring over this decision for 3 weeks now and if I don't do something soon I'll be looking at my car taking up room the garage in pieces for another season. I still have some bodywork and paint and subframe connectors to do which I won't do till the trans is in and finished so I gotta git this thang movin! Promotion claims it's good for 500HP at the wheels with the right clutch, we'll see. Kev
     
  19. mshred

    mshred The Green Manalishi

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    i meant fast sorry lol...and i meant fast on deciding promotion...but whatever you do, DO NOT buy one of their clutches...i dont think i have heard of anyone having good success with them...they hit hard
     
  20. kanders

    kanders Well-Known Member

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    I don't think I'll be buying anything of theirs, twice now I've been waiting several days for someone to return my call, last time it was over a week. Then they get mad at you when you tell them they are hard to get ahold of and thats to sell you something, wonder how long it would take if you had problems with their product? Kev
     
  21. mshred

    mshred The Green Manalishi

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    hey man, dont get too upset...everyone who knows promotion knows its impossible to get a hold of them, just like liberty is...they are busy working on the "pro" stuff, so anything else comes second...thats just how it is, since their bread and butter comes from the race car stuff they do

    good luck!
     
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