What boost are stock LET conrods and crank good for?
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Thread: What boost are stock LET conrods and crank good for?

  1. #1
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    What boost are stock LET conrods and crank good for?

    Tried searching the archives but found nothing. Basically is it worth doing "half a job" doing just the pistons? I'm running 1bar at the moment on the standard turbo.

    If I get a hybrid, what boost can I run with standard pistons?

    And with forged pistons and standard rods and crank?

    Cheers

    Tricky

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  3. #2
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    Its not just about what boost, its also about how much torque you are making and what revs you are using it at.

    As a rule of thumb though the standard are good from 350bhp at least if used with ARP rod bolts and new bearings, in fact TFS was running 400BHP plus on his with worn bearings and standard rod bolts and it still took over 18 months to die (but that was running nitrous, you cannot get the same power from the same bottom end as safely without nitrous, as nitrous power is gentler on the engine)

    Compression ratio will also make a difference, the actual pressure the pistons are subject to for a given level of boost is lower and over a longer time period on a lower CR motor, so a thicker head gasket or lower CR pistons will allow the rods to take more bhp than standard as well.

    Personally iwouldnt bother changing the rods on a LET unless you are going for more than the 400bhp ballpark if you are building the rest of it sensibley.


    Chip

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    "boost" is a misunderstood term

    It doesn't indicate force, or power - or even engine load (in the usual sense)

    It might even be irrelevant when it comes to selecting rods.

    check out my website, try the 'boost' link from the introduction page

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    its not boost but compression, power and torque that will break em..

    standard LET Rods are supposedly good for 500bhp Bolts should be replaced by ARP items tho
    The Vauxhall Bug; Once Bitten Forever Smitten

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    LOL @ all 3 of us typing exactly the same thing about boost at the same time.

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    lol - great minds thinking alike you reckon?
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    nah mate "fools seldom differ"

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    is it mentally draining mentioning nitrous in every single one of your replies ? lmao

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    the boys are correct in the whole boost issue.

    The load's are not the problem its the cycling. A rod fails after so many cycles.

    It could probbaly take a compression load of a few tons for a million years, same if it had a few tons clinging on to it.

    But when your doing both thats when the trouble arises, thus aftermarket rods etc usually come with a cycle life, like 10million cycles at an equiv of 7krpm.

    Some rods will go and go, others will fail sooner.
    I don't give a p-h-u-k whatcha gotta say!

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    Originally posted by 0ddball
    is it mentally draining mentioning nitrous in every single one of your replies ? lmao

    A little bit, im just waiting for one of the non-nitrous users on here with a cally turbo to do tens of thousands of miles with 400bhp+ though, and then ill have some examples of cars that dont use nitrous.

    As it is though, as far as im aware no one else on here at the moment can match TFS's time so his car is a good exmaple of what works and what doesnt.

    If he had just done the rod bolts and bearings like i told him to his original engine would still be fine, so it shows the rods are good for 400 easy.


    Chip

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    i almost just found 1 thread that didnt mention nitrous, it was your g/f nova thread, but then i noticed the nitrous sticker on the side, deeeenied

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    you want some NOS like Oddball?

    Also forgot to mention 400bhp or whatever from a turbo engine is easier on rods than 400 from an NA engine.
    I don't give a p-h-u-k whatcha gotta say!

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    [idle comment]
    Waaaay to many preachers on here these days......

    Not many people seem to be able to put their point across without being condescending.
    Shame, 'cos some of the points are worthwhile.
    [/idle comment]


    Sorry, please resume normal service.....


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    so steel rods are a waste of money? 350bhp limit no?>
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    Originally posted by observer
    so steel rods are a waste of money? 350bhp limit no?>
    Above 350ib/ft and the rods start snapping. Brian has never had a rolling road confirm his car at 400bhp either
    Sir, please step away from the car

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    12.9 seconds up the pod in a non stripped out car (including stereo and that bottle you keep going on about being so heavy) very clearly puts it in the 400bhp ball park, timing slips are a far better judge of power (given a consistant driver) than imaginary figures from rolling roads which vary so wildly.


    Chip

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    Hi Russ

    hey, didn't your standard engine (bar Phase 3) cally do a almost dead 13 sec quarter quite regularly, without nitrous or any other means of artificial support ?

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    Originally posted by RDS
    Above 350ib/ft and the rods start snapping. Brian has never had a rolling road confirm his car at 400bhp either


    Just for anyone who doesnt know how to do the maths and would rather think in BHP than LBFT

    350lbft=
    367bhp @ 5500rpm
    400bhp @ 6000rpm
    433bhp @ 6500rpm
    466bhp @ 7000rpm
    500bhp @ 7500rpm

    So claims the standard rods are good for 500bhp are backup up by what RDS is saying about the amount of torque they can withstand.

    Chip

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    Im pretty sure both myself and RDS have been told be 2 different people who work at SRE that the crank itself fine up to 500bhp
    PhilAstra@Hotmail.com

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    Originally posted by Gary
    Hi Russ

    hey, didn't your standard engine (bar Phase 3) cally do a almost dead 13 sec quarter quite regularly, without nitrous or any other means of artificial support ?
    Did 13.2's for a past time and the occasional 13.1 sommit!
    Sir, please step away from the car

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    Originally posted by Gary
    Hi Russ

    hey, didn't your standard engine (bar Phase 3) cally do a almost dead 13 sec quarter quite regularly, without nitrous or any other means of artificial support ?
    lol gary i take it your not a fan of these artficial engine steroids either....lollmao lmao lmao
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    yea last yr at pv2002 russ did v low 13's i think he got a 13.1...so a 12.9 with 400 bhp is not that great...he should have been into the mid 12's or low atleast
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    Awwww - I missed all the fun!

    12.9's very clearly puts it in the 400bhp ball park
    Really?!

    As several have said, (thanks, until now I thought people didn't like me ) 13.1's are achievable in a fully loaded cally turbo with only a paltry 300bhp.


    Now, any one wanna talk about good 60ft times?! lmao lmao

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    <all together now>

    WE LOVE YOU RUSS

    Aaaaaaahhh.....

  26. #25
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    Sorry should have put more detail in my post there for the pedants who wont bother looking at the rest of the facts themselves

    i should have said something like

    "making a 12.9 still despite blowing up the intercooler before the line and coasting accross in a standard weight calibra after getting a pretty average 60ft time due to crap tyres clearly puts it in the 400bhp ballpark"

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