Slant Six Forum :: Hyper Pak Exhaust Reproduction

10% relative to what?

Let's say you already have done head work, larger valves, porting, appropriate cam, carburetion/intake flow good, etc. and have Dutra Duals and good exhaust flow from the Dutra duals. Let's say you are at close to 200 hp. Then would the hyper pack give 10% more? I doubt it, but that is pure speculation on my part.

Let's say it means 10% from stock. A stock '67 slant has 145 hp, so 10% more would make it 169.5 hp, not too shabby...

Any other takes on this?

Let's say you already have done head work, larger valves, porting, appropriate cam, carburetion/intake flow good, etc. and have Dutra Duals and good exhaust flow from the Dutra duals.

There wasn't a significant power drop in 1972 when the 225's rating went from 145 to 115. The significant difference was in the rating system, which changed from SAE Gross Brake Horsepower (engine minus alternator, exhaust system, air cleaner, and other power-using accessories) to the more realistic SAE Net Horsepower (engine as installed in the car).

I read that in the old days, GM overstated HP numbers, Ford was about right and Mopar generally understated their numbers. Any truth to that?

If the answer is "no" then why did they bolt together in the first place?

brian

Is that needed to support the exhaust manifolds?

Quote:

Is that needed to support the exhaust manifolds?

No. The intake is what would need the support in my opinion. I am running them with a clifford 4 barrel and no support brackets.

Rick

I will try and get some video of the noise the make.

Author:	vntned [ Tue May 19, 2015 4:59 pm ]
Post subject:
So I recently picked up a hot rod car mag from 1961, was flipping through it and spotted a pic of the HyperPak exhaust manifolds. The article was jut talking in general about what modifications to do to get more power. Under the pic of the HP manifolds, it said Chrysler claims 10% gain from just the exhaust manifolds!

Author:	'67 Dart 270 [ Tue May 19, 2015 7:00 pm ]
Post subject:	Ok...
10% relative to what? Let's say you already have done head work, larger valves, porting, appropriate cam, carburetion/intake flow good, etc. and have Dutra Duals and good exhaust flow from the Dutra duals. Let's say you are at close to 200 hp. Then would the hyper pack give 10% more? I doubt it, but that is pure speculation on my part. Let's say it means 10% from stock. A stock '67 slant has 145 hp, so 10% more would make it 169.5 hp, not too shabby... Any other takes on this? brian

Author:	'67 Dart 270 [ Tue May 19, 2015 7:02 pm ]
Post subject:	tests will tell...
we can all try the new castings if this goes through and have actual data on our builds, before and after hyper packs... exciting prospect... brian

Author:	DusterIdiot [ Tue May 19, 2015 8:58 pm ]
Post subject:	Lol...
Quote: 10% relative to what? Let's say you already have done head work, larger valves, porting, appropriate cam, carburetion/intake flow good, etc. and have Dutra Duals and good exhaust flow from the Dutra duals. Let's say you are at close to 200 hp. Then would the hyper pack give 10% more? I doubt it, but that is pure speculation on my part. Let's say it means 10% from stock. A stock '67 slant has 145 hp, so 10% more would make it 169.5 hp, not too shabby... Any other takes on this? LOL....If only a 1967 225 got 145hp at the crank once you added the alternator, fan belt, power steering, and A/C back into the equation... love those gross HP numbers....110 HP at the rear axle/maybe...and use the hyperpak exhaust manifolds with the stock engine (assume adjustments to carburation because of better flow)...120-121HP...no problem....and since it's an adder...the bigger the build the better...up to a point... Quote: Let's say you already have done head work, larger valves, porting, appropriate cam, carburetion/intake flow good, etc. and have Dutra Duals and good exhaust flow from the Dutra duals. After putting that much time and effort into a 225...it would get Headers from the get go if hyperpak exhausts were not available...because you want everything you can get for race time... Just sayin'...

Author:	'67 Dart 270 [ Tue May 19, 2015 9:53 pm ]
Post subject:	curious
OK, so the factory numbers are not correct for hp at the crank? I assume lots of loss by time you get to rear wheels. How are those numbers generated, with no alternator or fan? I read that in the old days, GM overstated HP numbers, Ford was about right and Mopar generally understated their numbers. Any truth to that? brian

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Author:	DusterIdiot [ Wed May 20, 2015 6:32 am ]
Post subject:	Yep...
To Quote Dan from a previous engine post who hits it right on the nose about Pre-1972 Gross HP testing vs. 1972+ Net HP Testing: Quote: There wasn't a significant power drop in 1972 when the 225's rating went from 145 to 115. The significant difference was in the rating system, which changed from SAE Gross Brake Horsepower (engine minus alternator, exhaust system, air cleaner, and other power-using accessories) to the more realistic SAE Net Horsepower (engine as installed in the car). Quote: I read that in the old days, GM overstated HP numbers, Ford was about right and Mopar generally understated their numbers. Any truth to that? Manufacturers manipulated data so they either could boast their engines were better than the competition, or understate them so the insurance companies didn't scalp the driver if he was under a certain age and loose potential sales...in a fair amount of car magazine articles the media got slipped a prepped car, or in some cases they modded to car to get the most power out of it (a common trick was to unbolt the exhaust manifolds from the heads so the exhaust was free flowing...in one particular Ford Mustang Test they picked up .5 seconds in the 1/4 with that trick)...

Author:	slantzilla [ Wed May 20, 2015 7:19 am ]
Post subject:
A real good stock early Slant will put 95ish at the wheels. IMHO, the HP exhaust manifolds do a better job of being user friendly than the intake does. They are better than a stock manifold, but as DI said, they are not as good as headers. They do have the cool looking factor going for them too. The thing you have to remember, the HP parts have a lot of legend and lore attached to them that is nothing more than legend and lore.

Author:	'67 Dart 270 [ Wed May 20, 2015 11:01 am ]
Post subject:	legend and lore...
Thanks for posting Dan's previous information on how they reported HP, very interesting. For the 426 hemi dual quads in the Dart, I've read that it was purposefully detuned at the factory to tame it down a bit. One needed only to tweak it after they bought it to get gobs more power out of it. brian

Author:	'67 Dart 270 [ Wed May 20, 2015 12:13 pm ]
Post subject:	hyperpak bolt bosses
Question: the Hyperpak exhaust bolt bosses are to bolt the exhaust manifolds to the Hyperpak intake. Is that needed to support the exhaust manifolds? That is, if one uses a different intake manifold, does one need to fabricate something analogous on their intake to bolt to the exhaust bosses? If the answer is "no" then why did they bolt together in the first place? brian

Author:	65 dartman [ Wed May 20, 2015 1:01 pm ]
Post subject:	Re: hyperpak bolt bosses
Quote: If the answer is "no" then why did they bolt together in the first place? brian I suspect to support the Hyperpac intake would be my guess.

Author:	Rick Covalt [ Wed May 20, 2015 2:52 pm ]
Post subject:
Quote: Is that needed to support the exhaust manifolds? No. The intake is what would need the support in my opinion. I am running them with a clifford 4 barrel and no support brackets. Rick I will try and get some video of the noise this make.

Author:	Valleyant [ Wed May 20, 2015 5:41 pm ]
Post subject:
Quote: Quote: Is that needed to support the exhaust manifolds? No. The intake is what would need the support in my opinion. I am running them with a clifford 4 barrel and no support brackets. Rick I will try and get some video of the noise the make. awesome...that's noise I want to hear!!! lol

Author:	'67 Dart 270 [ Wed May 20, 2015 10:25 pm ]
Post subject:	cool beans...
Yes, videos are always great to see/hear... OK, good to know on the bosses. brian

Author:	Rick Covalt [ Sat Jun 06, 2015 1:29 pm ]
Post subject:
This past week I removed the Hyperpak exhaust manifolds and re-installed my Clifford long tubes. Before I pulled them off I did a test fit of the manifolds that Lou brought me. The Offy 4 barrel and the Offy 2 X 1 barrel will both work with very minimal problems. The 2X1 may need a very small clearance "grind" put on one of the rear exhaust manifold bolt bosses, and the 4 barrel may need a very small amount of grinding at number 1 intake runner. Both of these bolted up as is but I would probably clearance them just a bit. I will post some picture later after I upload them to Photobucket. I also test fit the same manifolds with Dan's Argentine manifold and they worked also. My plan is to hand off the exhaust manifolds to Lou in 2 weeks so he can check fit them on a engine with P/S and A/C brackets. Rick

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