I havent read any of the previous posts so excuse if im late on this but i would think that LS1 would have crushed you driven properly

 

With all this talk of low 12's with minor bolt ons, what kind of mph are these cars getting?

Also, it's a known fact that normally aspirated engines will lose torque with no backpressure (in the hp range relative to this discussion)....the exhaust gases lose velocity which makes it more difficult to effectively escape the exhaust ports. With a well setup exhaust, the exhaust gas maintains velocity which almost syphons the gases out of the port and manifold.

Jason

 

if by running no backpressure your talkin about running a cutout, Ive NEVER seen ANYBODY lose ANY TQ from 2500rpm+. Never seen a dyno below 2500 so cant confirm about tq loss below that, but I would believe it would be minimal other than off idle. Also, im pretty sure even a boosted motor will lose a little bit of low end tq (off idle) with open exhaust as well.

 

I wasn't talking about any specific setup or car. I've just read in a million car books that eliminating backpressure on a n/a street hp type car will result in a low end torque loss. With turbo cars, when under boost your talking about dynamic compression ratio's hitting 16:1 or higher....so loss of backpressure doesn't always equal loss of exhuast gas velocity. Depends on the application I guess.

Jason

 

Very true.

 

I don't get why people think that a LT1 can't hang with a LS1 from 80MPH+ rolls. The LS1 isn't god people Just FWIW some of the best H&C packages for the LT1 on stock bottomends are netting around 450rwhp. Also, some of the best for the LS1 is around 500rwhp on a stock bottom end. The LT1 has just as much potential.

 

Stock for stock, it can't.

You just contradicted yourself. How can the LT1 have "just as much potential" when the LT1 is 50 rwhp behind the LS1 mod for mod?

 

It's because of better flowing heads that stock LS1's have more top end power. They were just designed to pull harder in third gear then the LT1. But once you put a heads/cam package in a LT1 not only will they hang with them but they'll be beating most of them.

So far it's been proven that LS1's put out better numbers with heads/cam then a LT1. But what hasn't been proven (I don't think it has anyway) is whether the LS1 engine can take the power as well as the LT1's can. I'll be interested to see if a 500hp LS1 can get as many miles/passes as a LT1 pushing 400-450.

I'm not trying to insult the LT1 motor. It's a very strong engine with wicked potential. I love the way they sound with LT's too

LS1's are not God. But they were made by man who was made by God. Is that close enough? Of course you could say the same thing about the LT1 so damn that argument is right out the friggin window.

 

"meant to pull harder in third gear"?- do you even know what youre talkin about???

 

Of course. I'm running late for picking up my son so I'll elaborate when I get home. Five oclock whistle on a Friday > all

 

First off , it isnt just the head flow , It is the head desighn in general . Second off , the LS1 bottom end is even stronger then the LT1 . GM dont just make a new engine to be inferior to the old one . I am so ****ing sick of these " LS1 god " remarks . Its like you are not aloud to tell the truth because some sensitive person might take it as a direct insult about their cars .

 

From an 80 MPH roll the LT1 would get beat like a red headed step child , if you think im joking bring your LT1 on up here and ill show you . LS1's shine on the highway like you wouldnt beleive . My car hits 120 so fast its like a blink of the eye . I have raced so many LT1's already with absolutoey no competition . They compete way better in the 1/4 then they do form an 80 MPH roll . If you drove one , you wouldnt be wondering at all , because you would know .

 

ive raced a few on the freeway and they dont pull any harder up top than any other car with a similar trap. the ones ive raced will run even with me till about 110 and then start to lose steam and fall back by about a car by about 125ish.

BTW, im talkin about M6 lightly modded LS1 cars (cutout, lid, exhaust. etc). never raced an auto from a roll (or a stop actually) from 80+.

 

That's an excellent point. I apologise for how long it took me to get back. Playing Mr. Mom with my wife doing an open to close. To answer marioss as to why I made the comment of LS1's were designed to pull harder in third gear, here it is. Bare in mind this is for stock internal motors just the way GM designed them. Changing heads/cams will of course negate these numbers and create a whole new ball game.

Stock LS1 heads flow 245 cmf vs 205 on the LT1. That is not the real difference maker here IMO. What's more important to the top end is the LS1 heads are a 15 degree head vs the 23 degree on the LT1. This means the LS1 would give a near straight shot at the back of the intake valve. That allows the air to be less turbulent and less restricted on the LS1 vs the LT1. This in turn makes more power at higher RPM's.

Now if my memory serves me correctly (and correct me if I am wrong) the LS1 makes 335 tq @ 4000 rpms. Now when a 3.23 geared A4 LS1 goes WOT it tops out second gear about 80 mph and shifts to third. My RPM's only drop to 3500 and I find my 3rd gear pull is very hard because I'm right at the point where I make peak torque but a LT1 makes it's peak torque at lower RPM's (325 @ 2500 I think but again correct me if I'm wrong).

So when I said the LS1 was made to pull harder in third gear I only meant stock motor vs stock motor and because GM designed the LS1 engine to make more power at higher RPM's and 3rd gear is definately higher rpm's, or at least for me it is.

Again I meant no offense to anyone or anyones car. The LT1's with heads/cam packages are making some incredible power and ET's. I have heard of 450 RWHP LT1's so the potential is definately there.

 

Some of you guys really need to get a clue. A LT1 with CAI/LTs/gears is no joke and will run right with, if not pull, a (read) STRONG stock LS1 from a roll.

One thing I have noticed with LS1s is the huge variance in performance. I've seem stock LS1 cars trap 100 and I've seen them trap 107. If you take one of the weaker LS1s and throw LTs on it, you may have a what...105 mph car on your hands? On the same token, the LS1 might trap 111 with LTs...you really can't say one way or another. My buddy's 94 Z28 with CAI and LTs dynoed 310 rwhp and trapped 107 - plenty to beat most stock LS1s and plenty to hang with most lightly modded LS1s.

I own both a LT1 car and a LS1 car. Stock for stock, my SS would have blown the fakn doors off the LT1. However, throw LTs/cutout on my LT1 and it would have been a very close race but my SS runs pretty strong for a bone stock car. Take a LS1 that traps 102 bone stock, and that LT1 with LTs is going to run away from it.