Hey Guys:

I consider myself pretty knowledgeable on the internal combustion engine and I must say that I am somewhat amazed at the peak torque differences between the GMPP ZZ4 and the LS1 crate engines. GM lists the Peak torque as 400ft-lbs for the ZZ4 and 340ft-lbs for the LS-1. This does not make sense to me for several reasons. They are both the same displacement, similar compression ratio 10.25 for LS1 and 10:1 for ZZ4, both aluminum heads, etc. The LS-1 uses a tuned runner intake which should help the peak torque, but it makes 60 ft-lbs less???? The LS-1 has more compression, yet less torque?????? The LS-1 has better flowing heads and newer technology fast burn combustion chambers, yet less torque??? What am I missing here???
Is it the difference in cam timing that gives the torque boost to the ZZ4?? Duration is 208/220 (ZZ4) vs. 200/203deg @0.050 for the LS1, lift is about 0.500 for each cam, both hyd roller cams.

Thanks for the help!!

 

Short answer: It's the heads.

Take a look at the flow data for the LS1 heads vs Aluminum L98 heads, and you'll see.

The LS1 is a high RPM motor (for a pushrod, OHV V8). It doesn't generate the torque numbers of the ZZ4 at low RPM because of the size of the intake runners and the design of the intake manifold.

I own both. Trust me, the ZZ4 has WAY more low end torque than the LS1.

 

Hawk, thanks for the input, especially since you have driven both. What confuses me about the LS1 heads, is that usually, when you have a high rpm motor which has good flow and VE at higher rpm, The torque peak moves up in rpm, but also usually is a higher value. This I believed was due to the the inertial effects that ram the air into the cylinders since at higher rpm with good flow you get good air column velocity. No doubt the torque at low rpm will be less with the high rev engine. Even though the L98 aluminum heads will NEVER impress anyone on the flow bench....... they have some kind of magic for midrange torque, but 60 ft-lbs???? using a dual plane manifold????

 

the zz4 is a nice motor. i'd take an ls1 any day. as the guy before said, its all in the heads. ls1 heads flow like MAD, i mean CRAZY. i believe MTI (www.motorsporttech.com) heads flow 305cfm at .4" lift.. i think? check their page. its insane. ls1's are above and beyond any other motor(american) that has come out recently or a long time ago. as reference, the top AFR heads flow like 270cfm.. not much different, but i believe over all the ls1 will flow more(on average at all lift values). the ls1 is also under rated.. just ask anybody at www.ls1.com. the ls1 motor is the only stock motor i know of that i've seen run 11's at over 120mph with under 10psi of boost. if you read some really technical stuff, you'll hear about all the little things the gm guys put in the ls1. i dunno about the ls1 specifically(been a while since i read the article), but i know the first ls6 motor has a hollow cam(ls1 also has this), hollow valves, 1.7:1 rocker arm ratio,.. i cant rmeember the rest, but you get hte point. its a very badass motor. overall, i think the ls1 is faster than other motors that appear to put out the same power because its power curve is fat as crap from 3k to 6k. with minor mods, it will simply scream. can you tell i'm an advocate for ls1's?

 

makes me cry again because i missed that wrecked 98 Z28 for $3000 by a day..

 

Yes, the LS1 is a good motor. However, I strongly prefer installing a Gen I SBC into a thirdgen instead. LS1's are simply too much trouble and too much electronics to swap over and its not worth the extra time and money IMO. Or, if you have a set budget, you could get a Gen I running a LOT faster than the comparable LS1 set up, because LS1 parts are EXPENSIVE. Keep in mind no Gen I/II header will fit an LS1 because of its different exhaust port pattern, and it starts to become a real pain in the rear.

I wouldn't swap in an LS1 unless you just want to say you have one.

 

http://www.sdpc2000.com/cart.asp?act...id=120&pid=466


Not that expensive...

They have the wrong pix, obviously.

 

Still, that's about double what I paid for my ZZ4. And I wasn't really referring to the price of the crate motor itself, but the price of parts FOR it. Like headers ($1k), LS6 manifold ($400)... heads & cam is like $2k... it gets rediculous.

 

The Flow to go test from Chevy hi-perf had 240cfm at .5 and 252 at .6

The GM hi-tech test had 225 at .5 and 238 at .6

The port design is much better for high velocity and they have a good chamber.

The exhaust is also very good.. about 190... a good overall package.

You also need to compare the ZZ4 (gms hottest production crate motor) with the same LS version. Like the LS6. I think it is rated at 385 ft/lbs with all the accessories (including exhaust). The ZZ4 does not have the same exhaust. I think they are rated with full headers and 2 1/2 pipes.

When you look at aftermarket combinations, the LS platform seems to be peaking in the 525-530hp range for the 383-388 cubic inch motors. The 427 platforms can make about 575 i think.

That is probably about 20hp more than your average max effort LT1 (but not much more than that) and, it will cost you big bucks.

 

the LS1 numbers are at SAE rating. they are the same numbers they use in the car. if you ran a dyno on both without accessories the LS1 would be really close if not higher in hp and torque.

 

I'm not sure it's fair to compare the official power figures. Everyone knows the LS1 is highly underrated on HP, putting down 300 rwhp behind a 6spd on average. But the average torque is just over 300-310 ft-lbs at the rears too, from like 2800-5000 rpm or so if I remember correctly. That's not exactly weak in the torque department... I'd like to see dyno figures for a ZZ4 in front of a 6spd and see what kinda rear wheel numbers it puts down. Anyone have any? I wouldn't be surprised if the LS1 outpowered it in the real world...

 

You might see some if I ever get my car running.

ZZ4 crate, T56, Ford 9" w/3.89

Besides, I never said the ZZ4 made more HP. I just said it made more low end torque. And it DOES. Especially below 2000. And the difference off-idle is rediculous.

 

How about this to account for the torque difference:
ZZ4 dyno numbers are actually "gross" numbers since they are measured through long tube headers(improve torque in mid range versus shorty style), no real exhaust system and with no accessories on the engine. The LS1 is measured net with all accesories and the factory exhaust manifolds(come w/ the crate engine). So, if we take 400 ft-lbs and subract the std 15% for gross to net we get 400-60=340ft-lbs, almost exactly the same as the LS-1 rating. Also, the ZZ4 uses a 112 deg lobe separation angle cam where the LS1 is quite wide running at 117 degress. I have read that wide lobe separation cams reduce the midrange torque. So in the end, they really make about the same torque. Just some thoughts......

OOPS!! Zippy, just saw your response.... Guess we agree!

 

They may make the same peak torque. The torque curves do NOT look the same.

 

Here's a quick graph I found on ls1.com, 02 TA with a K&N: That's a ****load of torque all through the rpm range including right off idle. The ZZ4 beat that? Rear wheel numbers. I'd be really interested to see, somehow I don't see it happening though...

http://publish.hometown.aol.com/josh...es/dynows6.jpg

The 02s are slightly more powerful than the earlier cars on average it seems, but not by a whole lot...

 

I can't seem to get the dyno graph to load over here, so I can't tell you much. Honestly though, even with a lower gear ratio (3.23 vs. 3.42), I still feel the ZZ4 has more off-idle torque.

 

Thanks Ray! If I correct these rear wheel numbers, it puts the LS-1 somewhere between 380 and 400 ft-lbs NET at peak torque. This easily matches what a zz4 does with full accessories and full exhaust. My original question was related to peak torque, where the engine has its optimum volumetric efficiency. I understand this may occur at different rpms for the different engines, but based on displacement, compression, cylinder heads, and intake runner design, I beieve the LS-1 should equal or better the ZZ4 for peak torque. Its starting to look like that is the case, and the original discrepancy is based on different conditions where the numbers I had were measured. I feel much better now

 

I seems to work for me, but if anyone can't see it the dyno started reading at 2250 rpm it looks like, where it made just at/over 300 ft-lbs. It peaked up into the high 320s at 4000ish rpm. (peaked at 312 rwhp too by the way)

That seems darn high but after looking around LS1.com that seems to be about the norm for 01-02 LS1s, the previous years seem to score down a bit closer to 310 ft-lbs at peak.

Probably due to that cam swap around '00 or '01 or whenever it was for LS1s...

Without a ZZ4 graph I guess we can't compare a whole lot though. You may well be right and the ZZ4 does out torque the LS1 down low.

 

No, I'm having trouble with my net today, it doesn't want to display pictures.

The problem with the dynos is they ALL start around 2000rpm. I'm talking about the range from 700-1800 rpm or so. By 2000rpm I can easily believe the LS1 is making as much torque as the ZZ4, because that's where (SOTP) the LS1 really begins to take off. Before that, IMO, it is no contest. I think the LS1 heads are suffering from velocity problems at that point.

 

Ohh, here we go, I found a chassis dyno run from a ZZ4 as well. 324 ft-lbs peak



It does look like it managed to pull out a bit more torque, it only goes down to 3000 rpm though. This ZZ4 dyno is with an auto, so I dug up some A4 LS1 numbers. 306 rwhp and 312 torque was a quick reference for a stock 01 A4 car. I'll try to find a dyno graph of it.

The LS1 certainly holds it's own torque wise though. Down a bit at lower rpm like you were thinking. Though not really that much... It would be very interesting to see what things looked like just off idle like you are saying though.

I just love GMs ole horsepower rating game though, the ZZ4 is rated at what 355 hp now? The LS1 305. Yet the LS1 puts down 30ish more rear wheel hp. LOL, Good Ole GM...

 

one of the main resaons dyno charts don't read that low is there isn't a point in getting numbers that low. even with an automatic, torque converter stall speed is usually just under 2k stock. under wide open conditions, the engine rarely sees less than less that 2k and in some cases 3k depending on t/c. in the case of a stick, anytime your going to be going wot with a stick your likely launching higher than 2k and can always downshift if your cruising and need to go wot at less than 2k. the other issue is most dyno's can't hold high torque loads at that low of rpm. i'd never check mine there for them reasons along with it just being hard on the engine to be under a wot load at that low of rpm.

 

You're kidding, right? Daily drive a stick and tell me you don't go below 2000 rpm. Most of the time I cruise below 2000rpm! As far as WOT, if you live somewhere you can dump the clutch above 2k at every light, let me know, because I want to move there! And yes, I do often WOT away from stoplights after slipping the clutch to get going. I doubt any of those starts begin above 1000rpm.

However, I'm actually surprised at the dyno. By 3k I expected the LS1 to be ahead on torque. If that dyno is right, based on my SOTP feel I'd guess the ZZ4 has more of a torque advantage below 2000rpm than even I thought.

 

I didn't read the whole thread, but I figured I'd drop my $0.02 in I personally would go with the LS1/6 just because of one major thing I read. "High Performance Oil Consumption" The article said something about high performace suspensions causing a majority of oil ending up on one side of most GM V8s and many other V8s in high G turns. The LS1/6 are supposed to have something to reduce this problem (Can never be completly solved since oil is a fluid and will be acted on by the "ghost force" called centrifical (sp?) force. If you're just lookin to go in a straight line, thats one thing, but if you want to turn at high speed....
like I said, just my $0.02

 

well 99hawk120, i'm not kidding. i drive a 94 with a 6 speed so i have no reason to be below 2k at wot. i also cruise at less than 2k, but i'm not wide open when i'm cruising at that kind of rpm. i have 6 gears, it's easier to just downshift than put that kind of load on the engine. as far as launching, side step the clutch below 2k and it'll just bog and be a waste of time since if you have to launch it that low, your not likely going to be hooked up once rpm rises. as far as slipping the clutch, anyone with any common sense know's you don't slip the clutch at wot, you roll into the gas as your doing it otherwise your rpm will get too high causing you to get into the higher torque range defeating the purpose of slipping the clutch and either causing the clutch to not grab and keep slipping or lite the tires. anyone else with a stick agree or disagree?