torque drop on ls engine
12-26-2004, 03:04 AM
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torque drop on ls engine
Whats the deal with the massive torque drop on ls motors. In every dyno graph i've seen of an ls motor the torque just drops like crazy after 6k. Everyone seems to think that the problem is in the cylinder head and that porting would help a great deal. My question is, what can be done besides head porting, that will help flatten out the torque curve?
1) Skunk2 IM
2) Cams
3) Port and Polish
4) ls/vtec
1) Skunk2 IM
2) Cams
3) Port and Polish
4) ls/vtec
12-26-2004, 05:25 AM
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Re: torque drop on ls engine (redturbocivic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by redturbocivic »</TD></TR><TR><TD CLASS="quote">number 4</TD></TR></TABLE>
DRAGLS must have the only stock LS in the world that makes power all the way to redline lol...
DRAGLS must have the only stock LS in the world that makes power all the way to redline lol...
12-26-2004, 07:19 AM
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Re: torque drop on ls engine (DRAGLS)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DRAGLS »</TD></TR><TR><TD CLASS="quote">Here's my stock LS dyno graph at 14psi nothing fancy it held fine to redline...</TD></TR></TABLE>
:: taps finger ::
Please tell me your secrets.
:: taps finger ::
Please tell me your secrets.
12-26-2004, 07:40 AM
#6
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Re: torque drop on ls engine (0x64)
all I did different from the norm was I retarded the stock cams 3 degrees IN/EX
which increases top-end power while decreasing bottom end- it moves the overlap period later in the cycle to where is more effective for scavenging the cylinders at higher rpm.
which increases top-end power while decreasing bottom end- it moves the overlap period later in the cycle to where is more effective for scavenging the cylinders at higher rpm.
12-26-2004, 07:43 AM
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Re: torque drop on ls engine (turbols619)
One way to look at the torque drop off is that you have alot of area under the curve. ALL engines should drop in torque before redline, if they don't, you are not revving it high enough. Your best bet for getting the LS head to maintain torque higher is going to be a good set of cams and a skunk2 intake manifold.
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12-26-2004, 08:33 AM
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Re: (mildly interesting)
the reason most LS engines die off on the top end. Is due to the head. It just doesnt flow enough to make the power that high..
LS/vtec is a good way to fix it.
LS/vtec is a good way to fix it.
12-26-2004, 09:08 AM
#11
Re: torque drop on ls engine (turbols619)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbols619 »</TD></TR><TR><TD CLASS="quote">Whats the deal with the massive torque drop on ls motors. In every dyno graph i've seen of an ls motor the torque just drops like crazy after 6k. Everyone seems to think that the problem is in the cylinder head and that porting would help a great deal. My question is, what can be done besides head porting, that will help flatten out the torque curve?
1) Skunk2 IM
2) Cams
3) Port and Polish
4) ls/vtec</TD></TR></TABLE>
http://www.boosted-hybrid.com/viewtopic.php?t=127
Why do the questions asked by these two people seem so extremely similiar...
Good answers BTW in the B-H thread
1) Skunk2 IM
2) Cams
3) Port and Polish
4) ls/vtec</TD></TR></TABLE>
http://www.boosted-hybrid.com/viewtopic.php?t=127
Why do the questions asked by these two people seem so extremely similiar...
Good answers BTW in the B-H thread
12-26-2004, 10:37 AM
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Re: torque drop on ls engine (DRAGLS)
The funny thing about your graph is that not only are you running extremely rich, but some how your STOCK LS never drops in torque. You would assume that if retarding the cams a few degrees would make your car pull all the way to redline, everyone would be doing it, instead of going ls/vtec. Must be a new thing... 
12-26-2004, 03:47 PM
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Re: torque drop on ls engine (DRAGLS)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DRAGLS »</TD></TR><TR><TD CLASS="quote">I took mine to the 6800-7000 factory redline</TD></TR></TABLE>
well if you had kept revving it you would have had acceleration probably to 8k. not that it'd be a good idea on the stock valvetrain but the potential was there.
well if you had kept revving it you would have had acceleration probably to 8k. not that it'd be a good idea on the stock valvetrain but the potential was there.
12-26-2004, 04:11 PM
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Re: (Ckjeepin)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ckjeepin »</TD></TR><TR><TD CLASS="quote">the reason most LS engines die off on the top end. Is due to the head. It just doesnt flow enough to make the power that high..
LS/vtec is a good way to fix it.</TD></TR></TABLE>
You'll have to define "that" for me.
LS head flows plenty, requires you throw away cams.
LS/vtec is a good way to fix it.</TD></TR></TABLE>
You'll have to define "that" for me.
LS head flows plenty, requires you throw away cams.
12-26-2004, 06:21 PM
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Re: torque drop on ls engine (xenocron)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xenocron »</TD></TR><TR><TD CLASS="quote">
http://www.boosted-hybrid.com/viewtopic.php?t=127
</TD></TR></TABLE>
Good thread Chris.
http://www.boosted-hybrid.com/viewtopic.php?t=127
</TD></TR></TABLE>
Good thread Chris.
12-26-2004, 11:03 PM
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Re: torque drop on ls engine (Raunch)
DRAGLS had boost creep as you you can tell by the trq not going down and actually going up.
Even if you put a high flowing head on the LS bottom its going to lose trq before a GSR bottom would because of the rod/stroke ratio. Anytime you go with a higher stroke you typically sacrifice high rpm trq for more midrange trq. It usually drops off quicker.
Cams, head work, free flowing manifold, lighter valve train all contribute to a higher power band
Even if you put a high flowing head on the LS bottom its going to lose trq before a GSR bottom would because of the rod/stroke ratio. Anytime you go with a higher stroke you typically sacrifice high rpm trq for more midrange trq. It usually drops off quicker.
Cams, head work, free flowing manifold, lighter valve train all contribute to a higher power band
12-27-2004, 06:21 AM
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Re: torque drop on ls engine (SOUNDEFFECTS)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOUNDEFFECTS »</TD></TR><TR><TD CLASS="quote">DRAGLS had boost creep as you you can tell by the trq not going down and actually going up.
Even if you put a high flowing head on the LS bottom its going to lose trq before a GSR bottom would because of the rod/stroke ratio. Anytime you go with a higher stroke you typically sacrifice high rpm trq for more midrange trq. It usually drops off quicker.
Cams, head work, free flowing manifold, lighter valve train all contribute to a higher power band</TD></TR></TABLE>
There was no boost creep-Try again!!!
Even if you put a high flowing head on the LS bottom its going to lose trq before a GSR bottom would because of the rod/stroke ratio. Anytime you go with a higher stroke you typically sacrifice high rpm trq for more midrange trq. It usually drops off quicker.
Cams, head work, free flowing manifold, lighter valve train all contribute to a higher power band</TD></TR></TABLE>
There was no boost creep-Try again!!!
12-27-2004, 05:29 PM
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Re: torque drop on ls engine (DRAGLS)
Well its your car I really wouldn't know.
But from the graph around 6500rpm to 6600rpm it goes up kinda uncharacteristically of an LS motor. From most of the straight LS dyno I have seen they typically level out by 6000rpm and hold the same trq or lose trq after that. They don't just go up around 6500rpm, they don't have VTEC and aren't capable of switching any kind of cam lobes at a certain RPM. What kind of cams were in there anyhow?
The only possible conslusion I could think of would be boost creep, the air/fuel did get a little leaner at the same 6500-6600rpm. But who cares really I was just making an observation.
Heres a couple similar less powerful dynos
Like I said though if it had some cams then maybe I'm wrong
But from the graph around 6500rpm to 6600rpm it goes up kinda uncharacteristically of an LS motor. From most of the straight LS dyno I have seen they typically level out by 6000rpm and hold the same trq or lose trq after that. They don't just go up around 6500rpm, they don't have VTEC and aren't capable of switching any kind of cam lobes at a certain RPM. What kind of cams were in there anyhow?
The only possible conslusion I could think of would be boost creep, the air/fuel did get a little leaner at the same 6500-6600rpm. But who cares really I was just making an observation.
Heres a couple similar less powerful dynos
Like I said though if it had some cams then maybe I'm wrong