First of all, I don't know that much in detail about this topic, but if the new Hemi engine was a true hemispherical design, like the Superbird or Roadrunner, what would our performance result in? Would it be closer to the 6.1L 425 hp or more with today's technology?

Auto-tech gurus feel free to take over.

 

Probably not much different. In today's day a true Hemi really isn't a rarity, my Sunfire has a Hemi, Civics have Hemis, they just aren't marketed as such. Chrysler just did an excellent job marketing the Hemi, which is why so many people don't even realize that just about every 4V per cylinder DOHC engine on the market is a Hemi.

 

This is a cool link for those of you that have ever wondered how a HEMI engine really works.

http://auto.howstuffworks.com/hemi.htm

 

UNBELIEVABLE!!!!

TRUCK, thanks for the link!!

 

It's simply a "squished" hemi which gives much better control of combustion and is more efficient. I've got a couple "real" Mopar hemis and pound for pound and inch for inch the new is better. A fact of life! (and, I race, record setting antiques!) The "good ol' days" often leave much to be desired.

 

I don't see how the new HEMI is inferior to the Big Block 426. In a test of the 6.1 HEMI in the Magnum SRT-8 (I think it was a Motor Trend test), they found that the 6.1 produced the same amount of horsepower that the 426 did on the dyno! I'm sure it produces less torque, but it is smaller. Just remember that the 426 is not the HEMI to judge all other HEMIs by. It is also not the first HEMI ever built by Chrysler either. Look how the 6.1L HEMI does against the Corvette 6.0L with the compression ratios that both has. 425hp/420ft-lbs of tq with a 10.3:1 compression ratio (6.1L HEMI) vs. 400hp/400ft-lbs of tq with a 10.9 compression ratio (6.0L). The difference in the displacement between the two in cubics is 370 cu. in. (HEMI) vs. 364 cu. in. (vette). The displacement advantage is really minimal for the HEMI and the compression ratio advantage is significant for the vette, but the vette still lacks a significant 25hp & 20ft-lbs of tq. I don't see where it is falling short of expectations.

 

i do hope your not saying that the hemi in our trucks are DOHC, cause your wrong on that matter, but yes i will agree with u about the rest of it.

 

Also remember the HP ratings back in the 60's and 70's are rumored to be very inflated....

 

Give me a little bit of credit, I am a mechanic. Please re-read it, you will notice that I never really mentioned the New Hemi, I was talking about other cars, specifically small displacement 4-cylinders, and while they do not use a true Hemi head they do use a variant of the Hemi head, the Pent-Roof Hemi head.

The HP ratings weren't so much inflated as measured differently. Most of the HP ratings in the muscle car era were Gross HP and not the Net HP used today. Gross HP still measures the HP at the flywheel, but it is measured with none of the accessories on the engine, such as the Power Steering Pump, today HP is measured with all electronics and accessories hooked up to the engine.

 

oh i'm sayin i'm not givin ya some credit cuz i am. i think that statement you made was excellent, i just wanted to be sure that you weren't talkin about the new hemi's. but yeah, they all want to try and use some variation of a "hemi" head to try and get as much power as possible. and back in those days, in some vehicles they rated the HP lower then what it actually was for insurance reasons, so they could sell more cars.