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Old 12-30-2009, 03:34 AM   #1
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Default Building an LS1 for low end torque?

Hello all, hopefully it hasn't been asked before though I doubt that's the case, but looking at the general theme behind the common engine mods, it seems like they all work towards shifting the power band upward. Long tuber headers, higher duration cams, and minimizing exhaust backpressure and such all optimize the engine for high rpm performance. But from what I understand, even mild cams will mean a reduction in low-end torque over stock, right? With all of these mods in place, would that generally mean less pull in the 2000-3500 range, where most(ok some ) daily driving tends to occur? And if so, what can be done to beef up the low end in an LS1 short of changing displacement, rather than making gobs of power at 6500 but pulling like a geo metro until 3 or 4k?

Thanks
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Old 12-30-2009, 08:10 AM   #2
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Your cam selection (and stall if you were a auto) make the biggest impact on your powerband.
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Old 12-30-2009, 08:18 AM   #3
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Buy an LT1
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Old 12-30-2009, 09:07 PM   #4
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Yeah, I realize that cam selection is the central factor, but what specs would one go for to get better low end? Still something with durations longer than stock I assume? The TR224 I'm looking at is a fairly mild cam but would something like that not still reduce torque under 3K?
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Old 12-31-2009, 11:17 AM   #5
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Buy an LT1
That's funny considering the LT1's torque advantage is below 2000 rpm only.

Yes Cam change will build power at higher rpm but don't forget the fact that a torque increase happens acroos the total powerband aswell.
Slipping the clutch or a proper stall will put the engine in the powerband faster and make any torque lose down low feel non existent. Another thing to consider is proper rear gearing to maximize torque output.
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Old 12-31-2009, 12:25 PM   #6
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That's funny considering the LT1's torque advantage is below 2000 rpm only.

Yes Cam change will build power at higher rpm but don't forget the fact that a torque increase happens acroos the total powerband aswell.
Slipping the clutch or a proper stall will put the engine in the powerband faster and make any torque lose down low feel non existent. Another thing to consider is proper rear gearing to maximize torque output.
below 2000 rpms only...... you must not know lt1s to well my friend.
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Old 12-31-2009, 10:07 PM   #7
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Originally Posted by awizeking View Post
below 2000 rpms only...... you must not know lt1s to well my friend.
On the contrary I know them well enough and have seen the two engines Dyno graphs overlayed. Stock for stock the LT1's small power advantage ends when the revs begin to climb. I've owned both and Raced both and the only comparison is they shared the same platform.
BTW for a good read on LT1 vs LS1 Torque look at this
http://www.f-body.com/forum/printthr...2&page=1&pp=15
pay close attention to Injuneer's post.

Nuff said now lets get back on topic.
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Old 01-01-2010, 11:12 AM   #8
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Even a mild cam causes less torque in the 2000-3500 range then stock? ... I don't see it.

Here's my stock LS1 graph.



Final pull with heads and cam (224/228 .600 .600 +114) a perfect daily driver.



Now my current graph ... still NA ... still perfect on the street

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Old 01-01-2010, 11:57 AM   #9
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Originally Posted by 9T8W66 View Post
On the contrary I know them well enough and have seen the two engines Dyno graphs overlayed. Stock for stock the LT1's small power advantage ends when the revs begin to climb. I've owned both and Raced both and the only comparison is they shared the same platform.
BTW for a good read on LT1 vs LS1 Torque look at this
http://www.f-body.com/forum/printthr...2&page=1&pp=15
pay close attention to Injuneer's post.

Nuff said now lets get back on topic.
still doesnt justify what you said? you said below 2,000 rpms. it still continues to make power past that. an i wasnt comparing anything to an ls1, i was just commenting on your only below 2,000rpm comment. which even your linked proved wrong. 500rpms can make a world of differnce at the track!
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Old 01-01-2010, 01:47 PM   #10
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below 2,000 rpms. 500rpms can make a world of differnce at the track!
Seriously? How much time at the track do you think you are at that low of an RPM?
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Old 01-01-2010, 01:57 PM   #11
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say the peak power you make stops below 2,000rpms, if you could make that peak power rise say another 400-600 rpms you lookin at a couple tenths of of your time. that is what i ment, like mentioned in the gentelmens link above the tpi make 340tq but drops very quickly resulting in a poopy quarter mile. the lt1 making less tq for a longer amount of time resulting in a much better quarter. all i was trying to say was it still makes power above 2grand. 2-3 tenths at the track is a noticable win by looks an time.
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Old 01-01-2010, 02:53 PM   #12
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Quote:
Originally Posted by frozt54 View Post
Hello all, hopefully it hasn't been asked before though I doubt that's the case, but looking at the general theme behind the common engine mods, it seems like they all work towards shifting the power band upward. Long tuber headers, higher duration cams, and minimizing exhaust backpressure and such all optimize the engine for high rpm performance. But from what I understand, even mild cams will mean a reduction in low-end torque over stock, right? With all of these mods in place, would that generally mean less pull in the 2000-3500 range, where most(ok some ) daily driving tends to occur? And if so, what can be done to beef up the low end in an LS1 short of changing displacement, rather than making gobs of power at 6500 but pulling like a geo metro until 3 or 4k?

Thanks

There are several misconceptions in this.
Lets start with "low end torque." I don't know about you, but when my engine is at 3k or under, I'm in a higher gear cruising. If I speed up and don't down shift I'm sure not going to give it much gas or it'll bog the engine. If I want to speed up or do anything performance wise, I tend to down shift. Autos do this for you. If you want performance out of your manual car, DOWNSHIFT. Midrange is where you will feel the hard pull, not below 3k RPM. This is part of the reason why A4 cars with looser converters pull so much harder, because they're not wasting time below 3k RPM.

LT's. Header theory in a nut shell: Longer tubes are better for bottom end. Shorter tubes are for higher RPM.
LT's will give you a good gain across the RPM range and especially in the midrange where most performance driving and racing will occur. Just don't get a 1 7/8 primary LT, although the LS1 breathes enough that it handles a larger primary well.

High duration cams. What someone considers high duration is relative. Most in here like the 22X grinds. Some will say you have to spin the engine to 7k w/a big cam. Not true. There are several 230 grind that redline from 6-6.5K and some smaller cams that go that high or higher. I would shift my 226 grind around 6.5K, and I shift my 240/244 grind at the same shift points.
Compare the graph from this thread to the ones below.
http://www.ls1tech.com/forums/generation-iii-internal-engine/732392-recipe-500-rwhp-heads-cam.html
This is a big cam for a LS1 designed with max hp in mind. People talk about big cams not making power down low, so let's compare just to see how much. We have to start with 2.5K since that where the graphs begin. The numbers will be hp/TQ.
.........stock ........22x duration ...23X/24X duration
2.5K ..130/270 ...150/310 .........135/295
3k .....160/380 ...190/340 .........195/330
3.5k ..205/305 ...230/350 .........245/365
4k .....245/325 ...270/360 .........310/405
4.5k ..270/320 ...320/370 .........360/420
Keep in mind these are eyeballed numbers so think of them as approximations. The big cam is still better than stock down low and not much below the 220 grind. The small cam does well at low RPM and edges the larger one out until 3.5K. From 3.5k until redline (6500 for both aftermarket cams and 6k for the stock cam) the larger cam shines. No doubt the 220 grind would be fun part throttle and in traffic, but which do you think would win a race? ITs all just amatter of how you want your car to perform.
Here is another larger grind with great low end and more important, a very nice torque curve.
http://www.ls1tech.com/forums/dynamometer-results-comparisons/572811-dyno-results.html
Now if you want a small cam, I'd suggest getting one with a tight LSA 108-110 like the Aussies were running, or the new EPS lobes cams have had some good results.

Back pressure... Back pressure doesn't magically give you torque. If so, 2" cat backs would be great, but they will kill power down low too because they're too restrictive. What you want is a good balance between velocity and flow (decreased back pressure) which is dependent on your engine's demand. Velocity in the intake, heads, and exhaust build torque not restrictions (aka backpressure). Backpressure is not good. Get a good 3" catback and call it a day.

Other things to consider.
Gears: The mechanical advantage will make it feel like you have more bottom end.
Ported or aftermarket heads: Get small ports (205cc or so) and small chambers for higher compression.
LS6 intake: Another great mod that will give you gains across the board
Ported TB: Not much in power, but will give better throttle response. If you're wanting low end then you're wanting seat of the pants feel.
Traction: Tires and suspension. If you want to maximize your power at low RPM which can mean slow speeds, you don't want to waste it spinning your tires.
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Old 01-01-2010, 03:03 PM   #13
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say the peak power you make stops below 2,000rpms, if you could make that peak power rise say another 400-600 rpms you lookin at a couple tenths of of your time. that is what i ment, like mentioned in the gentelmens link above the tpi make 340tq but drops very quickly resulting in a poopy quarter mile. the lt1 making less tq for a longer amount of time resulting in a much better quarter. all i was trying to say was it still makes power above 2grand. 2-3 tenths at the track is a noticable win by looks an time.
Peak power @ 2400-2600 RPM? So you're redline is @ ~2400 RPM.

Joking aside, I get what you're saying and yes. A little less torque or even HP but for a longer duration does help given you can take advantage of the extended duration. This is the also true with the larger cams that so many on her don't like. Ya, they'll make less power under 3K RPM, but how much of a race is actually under 3k RPM? I know when I leave the line at 5K, I never see under 3. If I'm on street tires and I leave off idle I'm not at full throttle so it's a moot point because the amount of torque I can put down is limited by the tires. But, when I can get on it and go full throttle its when the larger cam's power band is pulling strong.
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Old 01-01-2010, 05:10 PM   #14
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well put, but when i stated peak tq it means peak not redline. a car can peak an slightly drop an level out. again all i was tryin to say is a lt1 is not just benifical below 2,000rpms.
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Old 01-01-2010, 06:27 PM   #15
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still doesnt justify what you said? you said below 2,000 rpms. it still continues to make power past that. an i wasnt comparing anything to an ls1, i was just commenting on your only below 2,000rpm comment. which even your linked proved wrong. 500rpms can make a world of differnce at the track!
Point taken but if it wasn't in comparison to the LS1 then why reply ? Because that is what my original statement was comparing and what this thread was originally about (Ls1 low end).
Also honestly I just found that link as I was posting it and I will retract my below 2000 rpm LT1 torque advantage statement, as it's been shown that there is no advantage.
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