Why does the lt4 hp/trq vary so much in stock configuration? See http://www.corvetteactioncenter.com/...96/96perf.html

Dan Wombles
St. Louis, MO

 

There are hundreds of threads discussing that issue. There are articles, photos, dyno pulls...etc etc

 

I was not asking for a smarta$$ response! I am sure every topic has been discussed in the past. If we all just relied on searches, then there would be no reason for timely communication between us.

I've done searches, finding the dyno info, etc. I just want someone to inform me as to why there would be so much variation straight from the factory? Were the engines hand built, causing variation?

Dan Wombles
St. Louis, MO

 

I didn't even try...

 

You will NEVER find a true answer to this. Just look at all the search results, and other information you find all over the internet.

You'll be lucky if you find more than 3 people that will agree with any listed results. And no, I am sure the engines were not hand built.
Chevrolet lists the hp/tq, and its the same in every official publication.

The variances you see are from 3rd party sources, and next to impossible to prove.

The more answers you find, the more confused you will be.

 

Due to GM's Variances in mass producing the Vette, some LT4 engines have tested with more or less power (within an acceptable range) than other Lt4 engines to keep costs down.

That's why hand built vehicle's such as Ferrari's have Consistant quality control over their products but, in the process can not produce 100,000+ vehicles a year and keep the cost under $60,000.

 

I doubt you will find any two cars that come in consistently with the manufacture's stated numbers.

I've seen numbers from "the so called experts" on the L98 engine than run anywhere from 5.7 sec 0 to 60, to 5.2 0 to 60. Doesn't sound like a bunch but in the world of sportscars that's a bunch. Especially since the LT1 is rated at 5.2 and I'm sure their numbers fluctuate as well.

So I guess I'm saying

 

I don't there was ever a single year when that many vettes were made and only about 6359 LT4 were made in 96. So while I don't disagree with opinion, a wee-bit off on the example .

 

I see you are a new owner of an LT4......Congratulations on your new vehicle....

Actually most stock or near stock LT4's dyno right around 300 Rear Wheel Horsepower...

.....personally I have always thought this wide variation of "stock" horsepower to be

......wonder what this place was that dynoed 125 LT4's.....that is about 1/50th of all the LT4's ever made...can anyone shed some light on how 125 LT4 Corvettes ended up on this one dyno??

 

 

Possibly there is some kind of variance in different dynos from different makers used under different testing conditions. That, or the LT4 had huge variance going down the same assembly line, either one...

 

Thanks! I am having a ball driving this car. Only took me 40 years to get a vette!

 

Chillax, PLRX is no troll or troublemaker - what he speaks of is exactly the truth.

I've done well beyond 100 chassis dyno pulls on my small collection of cars. I can tell you that the chassis dyno is a great way to dial your combo - but there are an incredible array of factors that come into play. None of my cars have ever dyno'd exactly the same on dyno pulls that were: held on different days, with different fuel, etc. I can also guarantee that if you were to ever select 125 of ANY model of car that you will see similar variation. Mass production is meant to make things in duplicate - but the fact is that there is still a certain amount of variation that can stack up in positive or negative ways. In a related note; *stock* class racers have been known to accumulate quantities of stock cylinder head and intake manifolds - then flow test all of them to find the most superior flowing. With any casting there is a certain amount of core shift that can place the ports in "slightly" different locations - and that will make all the difference in performance.

Keep in mind that not all dynos are likely to give the same results - they too have some variations. Plus different dyno operators conduct dyno pulls in different ways - there are several ways to "correctly" conduct a dyno session: straight pull, step. sweep, load, etc. Lastly, be wary of ringers: the "stock" engine that has already been massaged.

"Stock" does not mean the same thing to all people. Consider "stock" class LT1's in the NHRA running in the 10's at near 130 mph trap speeds.

All speculation aside, the dyno is a tool - the dragstrip itself is the ultimate dyno. All tools, especially measuring tools, are subject to how their operator uses them, correction methods, and so on.

Thomas

 

I absolutely agree on the very loose definition of "stock"

Dragstrip environment is probably one of the worst examples of stock....I remember one day, back in '68 or so, my trophy winning Dodge getting its butt kicked by a supposedly "stock" Plymouth that you could hear back off on the throttle a few hundred feet off the line...

..but seriously a 390 hp LT4 from the factory...

 

Yes, the LT4 is fabled to be the General's "mystery motor".

I've heard that under it's original design configuration, the LT4 put out about 400 bhp. This was greater than the LS1 coming out the following year, so it is said the General restricted the heads and put in a smaller cam. Of course, I've never heard anything from reliable sources i.e. the General himself to confirm.

The true output of the LT4 is among those mysteries like Area 51 and extraterestials. For me, I don't believe nor disbelieve, I just like to drive and enjoy it for what it is.