Calderone

I always read comments about the L98 Low end torque
that means that the power are on the lower rpms ? am i right ?
i install a cam on the L98,will the power move from the low end to the high end ? or the power will be the same on the low end and have more power at the high end ? i dont want the low end torque to dissapear
- not all the engines has that low end torque ?
how are the other engines (LT1,LT4,etc) performing in comparison with the L98 low end torque ?
thanx
ps : i want to know my engine a bit more everyday

cv67

Depends on the size cam you put in. You can compensate a bit with a torque converter a bit also.

85 500 horse

Your gearing has a lot to do with it also.

Mr Mojo

Not to knock anyone with the L98, but me and 65Z01 ran each other at the track and my LT1 beat him at every point down the track including launch. My car has the six speed vs his automatic, but his is a strong running L98 running 13.50's.
I can't access my home page right now, but I have a scan of my dyno and the timeslip from the above race.

aboatguy

DaleD

I'm not an expert, but I have read some things, so I'll chime in. As far as I have read, the L98 and LT1 should be very comparable down low. First gear up to 4k rpm, shouldn't be a lot of difference. The L98 was rated 345 ft/lb torque, the LT1 at 340 ft/lb. So, if both engines are running well, an L98 might get the edge on launch, maybe, you still have to factor in gearing, and the variables of manufacturing tolerances. My 87 might have 335 ft/lb from the factory, Calderone's might have 350 ft/lb, (mine was made on Monday!).

Where the LT1 starts to smoke an L98 is that it can wind out in first up to 6k, the L98 has to shift around 4.5k-5k, there it starts falling back and never catches up. If I was Calderone, I'd change the intake before I changed the cam. I'd go: Intake, headers, then cam and heads. Another option is to sell the L98 and buy an LT1 car. About the same $ involved either way. The difference is, the LT1 car will be worth more for resale. At least for the near future.

Red Tornado

aside from numbers, paper and ink, in the real world it'll feel about the same as an LT1, except worse, because your party is over at 4400 rpms which to me used to be a killjoy. yup, just for groceries, right down the raod 1 mile.

you can thank the puny, mismatched factory intake and then the puny excuse of an exhaust manifold. it all equals shortness of breath, like a cigarette habit.

yeah hail GM, they're freakin' brilliant. corvette power my azz.

StealthLT4

The intake for the L98 was designed for a 327 block...so you can see why the L98 is so powerful down low and loses power up top. While you can compensate for the extremely long runners of the intake manifold with some cam tuning, they will always be there. So, the only real way to get more power up top is to replace the cam and the intake with a miniram, superram, or something like that. A cam will only do so much.

Aurora40

Man, torque discussions never die, ehh? Sometimes I think torque is an excuse for losing. "So what if it got smoked by a 4-banger, it feels better when driving to the store". Maybe that's too far off the other side, though. I'm not trying to knock the L98 either. The motor is what it is, it's not a bad motor, but at the same time, not too many people are swapping L98's into things. I doubt too many people pulled their LT1 intake off to put TPI on and get that low-end torque feeling.

I'll say two things. One, if you believe torque at the wheels is really all that is important, then if you take a motor like the L98, extend the power band so that instead of dropping off at 4,500 rpm it drops off at 6,000 rpm, you can then increase the rear axle ratio proportionally so that 1st gear still tops out at the same vehicle speed (40mph or whatever it is). So torque at the rear wheel will be the same or increase, and power will increase. (In the given case I believe a 3.33:1 could be swapped for a 4.44:1 to maintain the same speed in gear at the drop off point)

Two if you believe torque is really the "bomb", then you must feel like the era of performance cars is over. For you it must have peaked in the gas crunch/emissions era of the late 1970's when you could buy a 454 with 400+ lb-ft of torque and 160hp.

vader86

that means that the power are on the lower rpms ? am i right ?

Yes, because of the intake design, the port velocity is highest at lower rpm. high port velocity=torque

i install a cam on the L98,will the power move from the low end to the high end ? or the power will be the same on the low end and have more power at the high end ? i dont want the low end torque to dissapear

Anything you do that increases HP will invariably move the torque peak up in the band, thus making you feel like you lost something down low.

- not all the engines has that low end torque ?
how are the other engines (LT1,LT4,etc) performing in comparison with the L98 low end torque ?

They dont have that low end feel of the L98. They have a rather flat power curve and so dont feel as torquey, but they are just as quick if you know how to drive them.

88BlackZ-51

The L-98 guys always talk about tq, because thats all it has going for it. Mine dynoed 321 rwtq in stock trim. I was underated!

It also dynoed 98rwhp.

88BlackZ-51

Jim's motor is tired as well. Take out a 91 L-98, and then take out a 92 LT-1. Both being stock, The L-98 will feel more powerful down low!

To the thread starter. Go drive an LT-1. You will see what I mean. But on the other hand, It kicks the L-98 up top!!

88BlackZ-51

It was a low 14 sec. Nothing wrong with that back in the mid-late 80's. It never had a problem beating on Porsche's/Mustang's/Camaro's etc....

DaleD

I've read some stuff on HP and torque and know just enough that I can make a total azz out of myself. And since I have already established I am an azz...

As I understand it, HP is torque over time. You can't get high HP without torque.
HP= (Torque*RPM)/5252

Therefore, if you have the torque, you have the potential to make HP. If you don't have torque, you don't have squat. And where does torque come from? Displacement and compression. Thats why starting with an L98 puts you steps ahead of the ricers.

For example if you make 100 ft/lb of torque, (a low number), and you can wind the engine out to 8000 rpm, (not likely), you still make only 152HP. If you use real numbers, 250 ft/lb and 6k, you get 285 HP. But those little four bangers have to wind hard to get that 285. The L98 gives you most of it's 250hp when you hit it.

The L98's problem is it quits making torque at high RPM because it runs out of breath. Open the intake, open the exhaust, and it will go.

BTW, I thought the intake for the L98 is for a 307 not a 327?

DaleD

You're barking up the wrong tree. Hot Rod is the resident, self admitted speed lunitic. I think he said he wants to go so fast his gums bleed on his 1 mile trip to the store.

I do agree putting a 307 intake on a 350 was stupid. But, I will also admit that for a 20 year old car, my L98 does a pretty nice job.

StealthLT4

You may be correct. In any case, a lot smaller than 350!

88BlackZ-51

I am barking up the wrong tree with Bradley. Now that is .

88BlackZ-51

It was for the Tune Port 305 in the 3rd Gen's.

Aurora40

I wasn't suggesting the OP go buy a cam and heads that will put him at 0 lb-ft of torque. Of course it takes some torque to do anything in a reciprocating motor.

And yes, the L98 has displacement going for it. Whether or not that puts you ahead of a 300hp ricer kind of depends on what you do with the car from there.

My point in relation to the original post though, is that from a performance standpoint, the LT1 is a better motor than the L98. The LT4 is a better motor than the L98. The LT5 is a better motor than the L98. What they give up in torque at the flywheel is trivial compared to what they gain in horsepower. Not to mention they came with a 3.45:1 axle vs a 3.33:1 to gain back about 5% in wheel torque.

In reality, if the 3.33:1 was good for the L98 with the ZF tranny, then the LT1 should have had more like a 3.73:1, and the LT4 and LT5 should have had even more gear than that. Then the engine improvements over the L98 would really be apparent from any speed. For the sake of the dramatic math, to get an LT5 to have the same speed-in-gear as the L98, it should have a 5.18:1 rear axle ratio. Then both cars would hit about 38mph in 1st gear. The L98 @ 4,500 rpm with a 3.33:1 and the LT5 @ 7,000 rpm with a 5.18:1. I have never been in an LT5 with 5.18:1 gears, but I suspect there is no one anywhere who would say it felt weaker at low speeds than a stock L98.

Somewhat off the topic and on the point you make about torque, in my opinion torque is somewhat meaningless. What is important is horsepower, and more specifically horsepower at the rpm you are at. The fact that it takes torque to create this is secondary. You can choose to focus on the torque, but you are missing the forest for the trees.

DaleD

There is no arguement. L98 < LT1 < LT4 < LT5
From the factory, the L98 has problems with aspiration. Not a true dual exhaust, restrictive exhaust at the manifolds, restrictive intake. Easily but not inexpensively fixed. I told the OP he had 2 options if he wanted more, sell the L98 and get an LT1 or fix his L98. It really will cost about the same either way, just that with an LT1, resale is better.
For those of us with L98s who have grown to like our car, it may be worth it to just fix the L98.

We'll have to disagree here. If you look at the equation: HP=(Torque*RPM)/5252, HP is the most easily manipulated. Torque is a given in a particular motor. It can be changed, but not easily. If your engine makes 150 ft/lb of torque, forget HP, it's not happening. The LT1 is 340 ft/lb, the L98 is 345 ft/lb, in my book that's no difference. Where they make the torque is slightly different. If you have a 4 banger and you're making big HP, there are only 3 ways to get there: 1) Have a 4 banger with huge displacement, 2) Crank up the compression to a high value, or 3) Wind the crap out of it.
Seems like option 1 would put you back to where you are with a V8, only it would make compression an issue.
Option 2 would require expensive components as would option 3.
If I have torque, I know I can get HP.