Wheelbase/HP Relationship??
 

Is this something that every combo has, or is it just certain ones? The reason I ask is that there are several engine combo's that are identical and depending on the wheelbase of the vehicle they have different HP ratings?

Whats up with that? For instant, Mopar 383/330 is rated at 280 in a big car and 287 in a small car(soon to be 294). Same motor, just different HP ratings. The only difference is the wheelbase 116/108.

The motors are identical.

This does not seem right. If it is right how come this is not done with the Fords and Chevrolets?



Later RJ

Re: Wheelbase/HP Relationship??
 

The 383 / 280 engine is the non-magnum engine; smaller cam than the 383 Magnum engine. Might even be a slight decrease in compression, check the specs. As used in the '67 A-Body cars, it also suffered from a very restrictive cast iron exhaust manifold.
The WB has nothing to do with anything. But sometimes it is a reflection on what is being run in competition and subsequently it may be hit by the AHFS.

Re: Wheelbase/HP Relationship??
 

Jeff

We are not talking about Pure Stock with factory exhaust manifolds here, we are talking about identical engine specs for these motors, regardless of what the Factory Rating was. We have the same motor being factored by Wheelbase and nothing else. Do you think that this is right?

R J

Re: Wheelbase/HP Relationship??
 

R J, could you be more specific in the particular car bodies?
Are we talking about A-Body vs. B-Body or A-Body vs. E-Body?

Re: Wheelbase/HP Relationship??
 

From what I read on the Classification and Blue Print Specs is that the 280 hp motor and the 325/330 HP motors are all identical as far as carb, cam, intake, rocker ratio, cam lift, deck, gasket, etc., etc.. So why are they separating the HP ratings on these motors according to "A" Body, "E" body, "B" Body "D" Body or Any Body and No Body???? I realize that the transmission does make a difference in the AHFS and it should be that way. What I am confused about is why the difference in the Wheelbases and "Body" differences?

I am really confused here and would appreciate it if somebody could explain why a Wheelbase is even considered a reason for different HP Rating.

Thanks RJ

Re: Wheelbase/HP Relationship??
 

R J, there is an actual difference in performance when the same engine is used in the various body styles. The combination will perform differently when put in an E-Body to a B-Body and from a A-Body to an E-Body. Ask Larry Hill how his engine combo would perform from a B-Body (Charger) to an E-Body (Cuda).

Re: Wheelbase/HP Relationship??
 

You know, now that I heard somebody explain it that way it makes a lot of sense.....

I have one question for anybody who would like to explain to me......is how come all the makes of cars are not adjusted this way?

I would like to see all Stock and SuperStock combo's done this way, anybody else feel that way? If it is good for the Mopars why not everybody else, or is there a hidden agenda in the NHRA Classification Guide group???

Maybe Travis could add something to this?

This does not seem right to me and should be an easy fix without a lot of hassle.


R J

Re: Wheelbase/HP Relationship??
 

It does happen in other makes. Check the 1969 Chevy 350/300. In the big car and the Vette its 290 in S and 310 in SS regardless of transmission type. But in the Chevy II and Camaro its 290 in S and 310 in SS stick but 318 in SS auto yet the big cars and the vette are at 310 for the SS auto. Think it has to do with how the AHFS hits a combo with regard to family. I would guess if we looked at enough Ford we could come up with the same thing.
As usual i could be wrong

Re: Wheelbase/HP Relationship??
 

If you check the years of the 383's as in 67 and 68's the exhaust valve changed from a 1.60 to a 1.74 , with a change in the cyl head # from a 916 to , i forgot the # for 68 - 70 head. I guess that is whats known as a senior moment!.....John............. It's back, it;s a 906 Head

Re: Wheelbase/HP Relationship??
 

John.....You are probably right about the difference between the 67 and 68 383's, what I was referring to was the difference in HP rating based solely on wheelbase in the 65-67 years for the 383 motors (280 HP has the same specs as the 325/330 HP). The big cars were rated at 280 and the smaller cars were 287.

I don't see a problem here with doing just that, as long as everyone is on the same LEVEL Playing Field. From what I have seen on the Classification Guide and the Blue Print Guide that is not the case for some engine combo's.

Looks like NHRA has already set a precedent with the Mopar ratings, why shouldn't every body have the same thing?

Do you think it should be??

Stewart....

I feel that the situation with the Chev combo you mention is that it has been run for so long and been changed up and down that it would be very hard to figure that particular combo out, one would have to go back a long way to see where it started off and follow the changes, and that would be very difficult. With the Mopar and other odd ball combo that were not as common or as good a combo as the 350 Chevrolets it is much easier to check. I don't remember many cars with the 383 combo running before a few years ago (2000?).

It should be the same for all makes with the same engine, not just for one brand


RJ

Re: Wheelbase/HP Relationship??
 

RJ
I took a little time and looked at Ford 1968 and it happens to everyone. The 428/335 hp E version is rated at 370 in the Fairlane and 375 in the Mustang. I think the engines are the same and it appears the Fairlane was dropped 5 hp in 05, likely thru a request. Again, I think it has to do with "families" in the AHFS. Mopar A body is a different family so when an A-body gets hit the B and E body doesn't.
Again, I could be wrong.

Re: Wheelbase/HP Relationship??
 

Stewart, you are correct. Also, the reason why you have not seen many competitive 383's and 440's in the past was due to the fact that many did not want to build these engines due to the CFM limitations of the carburetor. With the HP defactoring and the cam rule change, theses combinations with 383/440 engines with the Carter AVS carburetor, have become competitive. Also, let's not take away, and let's recognize the hard work and many hours of R&D by racers like Steve Wann and others that have made these engine combinations competitive in Stock and Super Stock class.

Re: Wheelbase/HP Relationship??
 

On both the 383 & 440 4-bbl, the hp on these cars have been lowered the past few years. The 383 used to be 315 or 320 hp when we ran it in the late 80's, now I think it's 280 or 290. The 440 4-bbl used to be the factory rating of 375, now it's 350. Both of these engines are now inline to be competitive. Neither are killer, but are 1.00 second under engines when done correctly.

SSDiv6 is correct about the 4-bbl engines. The carbs are not that bad, but the factory intake is horrible. To get into the cylinder head, the air/fuel charge goes UPHILL, it's that bad.

On the cam rule, this rule change did not help the 383 or 440. Both have had plenty of spec duration for a long time.

Re: Wheelbase/HP Relationship??
 

A good example for this is the 305 Chevy's of various years. Camaro's are more aero than , say a Malibu S/W. thus have more HP.

Re: Wheelbase/HP Relationship??
 

Chris! Not only have they (NHRA) lowered the HP on the B/RB engines but they now allow the 915 head to be used in place of the 916 if they put a 1.60 exhaust valve in the 915 which had a 1.74 ex valve. Yes the AVS can be made to work very well!..........Later, John