440lp vs 440hp

[Gus cuda]

I figure one of you motor gurus can tell me the difference. My engine is out of a 68 sport fury. It is stock rated at 350hp and 480tq. I know a 440hp is rated at 375hp and 480tq. That is only 25 horses more. Is the hp motor that much stronger? I know my car runs very strong with the lp variation.

[hemiken]

The difference would be in the either the cylinder heads or what pistons were used when assembled from new, you will find that the 440HP would have more compression than you Sport Fury engine to get that little extra squeeze of 25 horses. Still the same basic engine all the same, use it and abuse it a simple rebuild and give it more compression would make it feel like a whole different engine

[Gus cuda]

Thx for the reply. The way i understand they both are 10:5-1 with the same heads, intake and carb. I know some of it came from the exaust set up on the hp cars. My car has a full tti exaust including headers. Engine was said to be built to factory specs. Would my lp be closer to an hp now?

[polarbear123]

The difference would be in the either the cylinder heads or what pistons were used when assembled from new, you will find that the 440HP would have more compression than you Sport Fury engine to get that little extra squeeze of 25 horses. Still the same basic engine all the same, use it and abuse it a simple rebuild and give it more compression would make it feel like a whole different engine

                           

Your engine is more like 9:5-1 if it is cast.

[Gus cuda]

Crank is steel, if that is what your refering to.

[polarbear123]

if the heads are original they are cast iron and anything over 10-1 you could not use pump gas. I have cast heads at 10-1 and i have 500HP.

[Gus cuda]

Gotcha! As far as i know its all original. My 10:5-1 reference is from old ads from back in the day. Thanks for your reply.

[73Chally]

I think you're trying to read into it too much.  The blocks would be the same, with the hp having some different internals.  The horsepower ratings were all over the place in those days, and are irrelevant if the engine has been rebuilt.  People are making 440 motor home blocks pump out 500+hp.  A proper rebuild today with tighter specs is going to give you a better motor than what rolled off the line.

[Gus cuda]

Yeah i understand anything can be built, there is 1000hp honda civics afterall. I was just thinking stock to stock. Basically it sounds like not much difference between the two. Im just trying to learn more about my car. Thanks gus

[bad440]

Block, heads, steel crank on both, only difference for that 25 HP is exhaust manifolds and cam, that's it. They are basically the same. Compression, pistons, etc the same.

[Gus cuda]

Bad440, yes i have heard the hp has a rockier cam, my guess is that would be the major difference. Thx

[cjm]

In 68 the HP was 25hp more because of the difference in Carb  & Cam  (375hp - CarterAVS, cam 455/470) (350hp - Holley, cam 431/443)...  no other differences..

[Gus cuda]

Cjm, thx for your response. I thought they both used a carter, but im not 100% sure. Sounds like you know whats what so i have no reason to doubt you. It seems my 440lp is a very good engine then. This makes me very happy! If the difference is this small, i gotta ask why the hp block is held with such high regard?

[Chryco Psycho]

no good reason , the HP block is just a stamping

[bad440]

Should make a note here, after late 1973, the 440 began using the cast crank, low compression came in in 1972, the blocks from 1976 and on were very thin wall and Chrysler recommended no more than .020 on the overbore. I have heard of guys boring beyond the .020 but in my opinion would be risky. The best blocks were from 68 to 72, they also had an extra rib along the upper side of each block to prevent a cracking problem, some earlier blocks had.