Divenut
Well-Known Member
Net is determined with accessories in place, the parasitic power loss is what attributes to the lower HP numbers Mopar410. Gross is straight HP without accessories etc...
70" 340 vs 72" 340 specs please
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Net is determined with accessories in place, the parasitic power loss is what attributes to the lower HP numbers Mopar410. Gross is straight HP without accessories etc...
Thats basicle what I thought but what "accessories" are you talking about,just engine bolt ons like waterpump,altenator and power steering pump?I always heard it was with the enigine in the car measured to the tire as a dyno would measure HP.
Divenut
Well-Known Member
Yep... Now "power to the wheels" (whp =wheel HP) is just that, and is even lower than Net HP due to additional parasitic loss via the transmission/drivetrain, especially with automatic transmissions.
Pat
That doesn't add up right.My 06 charger has 350hp but at the wheel it can lose between 35-50 hp depends on the car.So loseing 40 just with those bolt ons seems high.
take or leave it thats how it was done
magnumminded
Well-Known Member
I'm with what these guys said on the net and gross power ratings. Anyways, with the 340; didn't NHRA dyno test one and get around 315-325 hp gross? I think Gross was also with headers I believe if I remember correctly.
nhra uses math to figure the power rating how quick the car is and how fast, the weight of the car and so on. it does figure about 315-325 im not sure were it is. don't know about the headers could be true. maybe someone on here really knows
magnumminded
Well-Known Member
I think they were using a 68-69 Dart Swinger 340 as a mule maybe? I can't remember. As for the headers, I read it somewhere but, can't remember but, who is to say it is accurate.
sheba
Member
do you know the model number on the thermoquad for the 72 340 demon please am rebuilding a numbers matching car and trying to get it all correct
Net Hp the engine has all the accessories attached, factory engine tune and exhaust so pretty much the way it sit in your car, gross hp has no standard it's any the manufacture wants to do it, it could be with no or some accessories, open manifolds or even open headers and performance tune or they could rate it with an all out lie Dodge seemed to under rate their engine and Chev seemed to over rate.
OldmanRick
Well-Known Member
According to a thread on Moparts, the Auto # is 6139S and the manual is 6138S. I'll try and verify by another source if possible and post here.
Ok, i found this also..........http://promaxcarbs.bizland.com/thermoquad.htm
sheba
Member
Proving once again the people who use these forums are the best thanks
Hersbird
Well-Known Member
The factory 275 is a gross under-rating as pointed out. The cars made more the 68-71. I don't know how accurate the ratings were on the 72 and 73 but the early ones were really 320hp@5600 rpm. Note the stock 340 may very well have made 275hp@5000 rpm but it wasn't done pulling at that point! LOL!
Also note thats more then the real numbers put out b the boss 302 mustang or the early 302 z/28 motor which both made 310 hp@6200 rpm.
Also note thats more then the real numbers put out b the boss 302 mustang or the early 302 z/28 motor which both made 310 hp@6200 rpm.
D-mailman
Well-Known Member
The stock flywheel HP for 68-70 was 310/315 range. The '70 Six Pac made 325 and the '71 made 330 actual HP. ' 71 was best year for HP. It had the good compression and the well designed TQ and intake and large vales. The '72 made 295/300 range HP . Only difference between '71 and '72 model was the Pistons were down in the bore .100 as was stated above and the 1.880 intake valves which really made very little difference. The '72 would run just as hard as any of the earlier models, but the '71 was the hottest of the 340 offerings ....even better than the six pac cars. According to NHRA .
Terry
Terry
ir3333
Well-Known Member
..didn't Dulcich dyno an early 340 built to stock specs at 281 hp?
..Mopar muscle tested headers on a 300 hp 360 crate motor and i think averaged about 12 hp increase.
..Mopar muscle tested headers on a 300 hp 360 crate motor and i think averaged about 12 hp increase.
swinger340
Well-Known Member
As many have stated already 68-69 were 10.5:1 comp 70-71 were 10.25:1 comp w forged crank internally balanced and had 2:02 intake valves. 72-73 were 8.5:1 comp with a cast crank and externally balanced w 1:88 intake valves. The 2 engines don't really compare. The 72 340 goes about like a 70 318. I have built up the 72-73 340s with a set of higher comp pistons and a bit more cam. I don't believe the 2:02s make all that much diff unless you are turning over 6000
AdamR
Big Member
Im sorry I call b.s. on this statement. The 72-73 340 didnt make that much less power then the earlier ones. 1 point of compression and a smaller intake valve were the only down grades (actually measured compression of the early cars is less then advertised.) and some will argue the drop in valve size making a difference. Cam stayed the same, Intake and carb was an improvement.
Theres a reason guys run 71 and later cars in stock classes and Ive heard the smaller intake valve is actually a plus in that class.
a 70 318 has probably about the same actual compression as a 72 340, Less cam, worse flowing heads, intake, carb and exhaust so if it is out running any 340 then the 340 has serious issues.
swinger340
Well-Known Member
Call B.S. all you want. I have owned and driven both early and late 340s. The 72-73 don't go that well stock. It is what it is. I did not say the 70 318 was out running the 72 340, but with only 15 more HP, they do seem to go about the same... If you would like you can try my uncles 70 318 duster w only 14K (bought new in 69) on it and my Fathers 72 340 Demon w 40k on it and you cant tell the difference in power driving the two. My father is disgusted with the 72 340 and the fact that my uncles 318 stays rite with it. Bone stock that is... Of course with a little work it can be made to go alot better. Im not trying to argue, Im just saying these two particular cars go very close to the same.
AdamR
Big Member
Ive owned my share of both also.
OldmanRick
Well-Known Member
I've been in both also, back then. What i recall was the earlier hi-comp cars would pull stronger and stronger as the r's went up and the low-comp cars had a similar low end, but felt like the power curve was more flat. I do know carb and timing adjustments made the later cars pretty strong considering equal competetion.
D-mailman
Well-Known Member
I will add to this debate my example. '72 Duster 340 with 98,000 on the odometer ALL stock , Auto . Only changes being an aluminum intake and a small 280/480 Aliance hyd. cam small tube 1 5/8 " headers , 391 gears and skinny E70/14 tires ran a best 13.53 @ 104 and would run 13.60 @ 103/104 every time out. Yes I still ran the stock TQ with an adapter to work with the square flange manifold. This car ALL stock was a solid mid to low 14 car. Right in the middle of where the 70 and 71 cars ran. Also Demons were just about 150 lbs. heavier than Dusters or Darts (true) so that might explain some of the lazy performance of your Dad's 340 Demon. EVERY '72 340 I ever saw ran very strong. JMHO
Terry
Terry
perfacar
Well-Known Member
hi, I looked at national records for 340 cars. E/SA record, 10.58 @ 123.76 mph, 1973 duster with low comp 340, F/SA, 10.73 , 1969 340 b 'cuda, with high comp 340. just food for thought. the 72 -73 340's can run fast.
AdamR
Big Member
Yup, The stock class guys will pick the better carb over better compression almost every time.
I tried finding some PureStock #s but no luck.
If you read the old DC/Mopar Perf manual they tell you the first upgrade to make on your 68-70 340 is to use a 71-73 intake/carb.
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