JagV12 is going to teach us Gross vs. Net HP

In reply to Steve_Jones :

Yep. He's not the only one that got banned. 

Stampie (FS) said:

In reply to frenchyd :

You still haven't answered my question.  What year Jag V12 made 61 more horsepower than a LS6 454?  Now I'll answer your question.  No I do not believe it made 325 installed HP.  That engine was widely known to be underrated for insurance/factory racing purposes.  I believe it made a lot more than 325.  Are you going to answer my questions or keep repeating your Jag V12 myths?

Weren't the L88 engines close to 550hp? Or was that the ZL1?

Certainly the "290"hp SCCA Trans-Am homologation small blocks (the series that Pontiac got a name from) made waaaay more than 290hp.  There was a recent-ish article where they built replicas of the Boss 302 and Chevy DZ302 and they made in the 350-400hp range, in the 7000+ range and not the rated 5800rpm.

This was not just for insurance or NHRA factor-finagling, but also for warranty reasons.  They didn't want to have to deal with a lot of street driven warranty claims, so they deliberately underrated them so only racers would buy them.

spitfirebill said:

It's like a train wreck.  

That's way more entertaining to watch than Fenchys constant condescending , often incorrect, and sometimes bigoted posts all over the forum on all subjects 

I do not understand the Frenchie hate. I guess it goes way way back for some of you.

Really this is the big topic?  There are SAE standards for gross and net hp.  Rear wheel dyno hp is neither.  
 

And we all know certain engines were underrated by the factory for a myriad of reasons.  In Japan all high hp cars made 276 ho for a decade due to the laws.  
 

I was really hoping to get a break from the vitriol of the internet by visiting GRM.....  

          So, what was the point of all this rhetoric ?

I wonder if there was a Gentleman's Agreement between Jaguar and GM, and both engines are actually underrated.

Steve_Jones said:

The only person that can clear it up is MGuar, but he got banned. Figures. 

He's still Mguar everywhere else on the internet lol

AnthonyGS (Forum Supporter) said:

Really this is the big topic?  There are SAE standards for gross and net hp.  Rear wheel dyno hp is neither. 

There really wasn't a standard for gross horsepower.  They might run with no accessories, with ignition timing altered to the best setting at every point in the curve (gotta love mechanical timing), or they might run as-installed.  And then the marketing and warranty departments would file for a fudge factor one way or the other.  Kind of like how all of the top high performance engines in the 60s made 425 horsepower, from every manufacturer, even though the engines kept getting bigger, the cylinder heads kept getting better, the cars kept getting heavier, and acceleration kept getting faster.  One exception was for the Corvette, which would get an automatic 10 hp bump compared to a Camaro or Chevelle or Impala, even though it was the same engine.

Antihero (Forum Supporter) said:

I will, as always in the eleventy billion times a v12 jaaaaggg I mentioned, would like to say this.

 

There's a company called "JagsThatRun" that has literally made it's fortune taking the v12s out and putting in a SBC. No matter what.....that's hilarious

I used to have a friend who did the same thing. In fact I used to get a lot of those "junk"  V12's  that when I pulled them apart were in perfect shape. 
     Then I started to realize what was really going on.  
In Short it was theft.  Take out a perfectly good engine and replace it with a cleaned up and painted  Junkyard engine.   Or just as bad a crate engine.    Thousands of dollars taken from some trusting guy because a $10 GM ignition module quit working or a $3 piece of vacuum hose cracked.  Maybe a ground wire got loose or dirty.   Those V12's are so complicated.   What nonesense, they work just the same as any other engine.  Just 12 instead of 4-6-8 
             Who's fault is it?  The owners for not knowing who to trust his car with?  The Shop for taking advantage of a trusting customer? The mechanic who either through ignorance, lack of training, or dishonesty  earned a nice paycheck.  
I know it wasn't only Jaguars  I had a dealer mechanic try to tell me the Vega had a cracked head when  he  put the timing belt on one tooth off. 
      Heck every dealership I've been to included ones I've trusted eventually tried to screw me.   I paid for Mobile One in an oil change and got regular oil. The mechanic and Service writer both tried to tell me that Moble One is now green. Instead of clear.  
     Lifetime warranty's that aren't honored, Trying to sell me a $700 brake job when the pads were barely 1/2 gone?    

SAE standards for both gross and net horsepower reported here.

https://ateupwithmotor.com/terms-technology-definitions/gross-versus-net-horsepower/

Since at one time I did this experiment using these standards on an engine dyno.....  but yeah they exist.  
 

There is no enforcement body, and no way to know who reported what or why though.

If you never read Jim Wanger's book "Glory Days" add it to your list.  

bobzilla said:

WEll, according to the internets the most powerful stock Jag V12 from Jag was 333hp/365tq as advertised in 1993. There were TWR variants that were punched out to 7.4L that made 750hp but thats not a stock Jag V12.

So the answer is: None.

EDIT: I guess you could find like a truck motor or something. The TBI 454 from like 1990 made 230-255hp but 385-405 tq. 1990 V12 would have been 285hp/319tq.. That's 55.... so we're getting close. 

Bobzilla.   Your Jaguar numbers are a little off but so are the Chevy numbers too. Plus there is that whole SAE vs DIN thing.  Then there is world numbers,  and American numbers for Jaguars.  Plus the first years with carbs only had 244 hp. But our own Loosecannon picked up 40 more horsepower just cutting off the dogleg in the intake manifold to get it to fit under the XKE bonnet. 
     I grab a Shop manual From England and the Jaguar has 291 horsepower ( except the 1980 which is 299) an American manual has it at 262. 
       But really, does it matter?  Except for 4479 ( or is it 4439?)  454 LS 6's  Most big block Chevy's were either ordinary hydraulic camshaft mild grocery getters  or truck engines.  

However,  about 300,000 V12's are out there really cheap. 

Pete. (l33t FS) said:

Stampie (FS) said:

In reply to frenchyd :

You still haven't answered my question.  What year Jag V12 made 61 more horsepower than a LS6 454?  Now I'll answer your question.  No I do not believe it made 325 installed HP.  That engine was widely known to be underrated for insurance/factory racing purposes.  I believe it made a lot more than 325.  Are you going to answer my questions or keep repeating your Jag V12 myths?

Weren't the L88 engines close to 550hp? Or was that the ZL1?

 

Certainly the "290"hp SCCA Trans-Am homologation small blocks (the series that Pontiac got a name from) made waaaay more than 290hp.  There was a recent-ish article where they built replicas of the Boss 302 and Chevy DZ302 and they made in the 350-400hp range, in the 7000+ range and not the rated 5800rpm.

 

This was not just for insurance or NHRA factor-finagling, but also for warranty reasons.  They didn't want to have to deal with a lot of street driven warranty claims, so they deliberately underrated them so only racers would buy them.

Pretty sure the ZL1 engine was massively underrated for racers only kinda thing.  

Antihero (Forum Supporter) said:

Also I'd like to add Ive known 3 people with jag v12s.

 

Also, Ive never known anyone with a running jaaaaggg v12

I've seen one that I know of, possibly a second but I never confirmed it still had a Jaaaaaaag engine in it 

Stampie (FS) said:

So I do have a dry sense of humor.  About 95% of this thread is me having fun.  I love engines.  All kinds of engines.  I currently own 10 totally different families of engines.  If I were building a car to race a Jaguar V12 wouldn't be on my list.  If I were building a car to show off an eye candy engine then yeah the Jag V12 would be on the list. 

I don't know how much racing you've done and I guess I should also add engine building for race cars. But if you buy a motor to go racing a high strength Steel forging is a very good thing. If it's been hardened even better. Like a Jaguar crankshaft.  
     Most Chevy's have cast Iron crankshafts. And none are hardened.  All Chevies use bolts to hold the head on but racers need studs. NASCAR engines have zero production parts. Nothing off the assembly line is good enough.  
           
     For racing? Look at the parts in a Jaguar. Then compare them with the parts in a Chevy.
 

     Can you make a lot of power with a Chevy?  Sure. Lots of off the shelf parts out there. Just put the right combination together and you'll make a powerful engine.  Ask the Chevy experts the best combination of parts. Now look at what you've spent.  
     

AnthonyGS (Forum Supporter) said:

SAE standards for both gross and net horsepower reported here.

https://ateupwithmotor.com/terms-technology-definitions/gross-versus-net-horsepower/

Since at one time I did this experiment using these standards on an engine dyno.....  but yeah they exist.  
 

There is no enforcement body, and no way to know who reported what or why though.

If you never read Jim Wanger's book "Glory Days" add it to your list.  

When I was building serious race motors I started to use engine dyno's. The trouble is sometimes I'd chase my tail.   One engine pull the thing made 392 hp.  Try a few different parts and go back to the original set up and now it made 403. 
     That was air density.  It would change and the power with it.  This was before computer print outs. We'd make note of the dials. 
      Then we started with flow benches. One shop would flow them as they were. The  next shop would flow them with a clay lip smoothing airflow in or out. 
     Finally they came out with chassis Dyno' s and wow!   Were  those numbers optimistic. It was like a race to show big numbers. 
    

bearmtnmartin (Forum Supporter) said:

I do not understand the Frenchie hate. I guess it goes way way back for some of you.

Stampie (FS) said:

I'm sorry I used to work on planes so my hearing isn't too good.  What year did you say made 61 more HP than the LS6?

Did you know that Frank Whittle travelled forward in time and used the Jaguar blower motor as inspiration for the compressor section in his engine?

I just finished reading through the whole thread so far...

In reply to AAZCD (Forum Supporter) :

Let me try to help.  No matter how you measure it none of your M96 engines make as much power as a Jag V12 or a Chevy hi po 454.  They are all in a way better chassis though!  
 

Thanks again for the turn signal assembly.  It's happy in my yellow 986.  

This thread makes me long for the joy and encouragement of political threads. 

In reply to SVreX (Forum Supporter) :

No, no not for me. I don't like dogpiles.

So over in the Assetto Corsa game thread we will be proving that........  I have no idea what we will be proving actually.  But we will be finding a V12 Jag based car (XJS v12 probably) and we will be racing it against some sort of big block American V8 car. (Chevele 454 maybe). I figure that what ever the results are we can take them and come up with some definitive conclusion about this. If nothing else we are going to have a whole bunch of fun thanks to this thread.