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volumetric efficiency

Siestarider

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#1
Musing about older cars vs new cars got me thinking about engine volumetric efficiency. For decades the small block Chevy was performance per dollar king. 327/327 ci/hp was good stock #. If you wanted 450 hp, change all the intenals, valves, cam, carb, manifolds, headers, exhaust, etc. Might cost $10K, could cost lot more.

Our car comes with 197 hp, or 2 hp/ci, twice as much as a high performance small block. I doubt any amount of money could make 654 hp from a 327 ci small block.

The latest Gibson (Zytec) racing engine for LMP 2 makes 2.54 hp/ci. It is naturally aspirated. I could not find a price online, more than $50K likely.

Want to make the same volumetric efficiency as the 2017 Gibsons that will be at all the endurance races? You need 246 hp. We have members' reports of reaching that with a tune.

At most a hybrid turbo, I/C and some tuning, keep same intake, maifolds, exhaust, probably cost less than $3K and you already have the brakes, suspension, chassis and tires to handle the extra hp.

I know, we are turbo-charged and they are not. I know racing turbos make a lot more hp/volume. I am speaking more to what real folks can afford and drive daily. Of course, there is real joy in big torque early, turbos offer it and N/A does not.

No wonder we are loving these cars. Amazing facts for fun and tell, but only among ourselves. One of the best things about it is no one else knows.
 


Quisp

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#2
I had a 350 camaro in 77 with at least 450hp. Didn't cost near 10k to get it. Maybe in todays dollars. Than there's LS1-3's even in todays money you could make way more the 450 for a couple grand.
 


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#3
You can make crazy hp cheap all day long. If you want that hp to last, that's where the $$ start flying out of your pocket.

That said, a factory stock car that has 2 hp per ci is crazy [emoji14]
 


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#4
The closest N/A vehicle to this I believe is the 458 Speciale with 2.18hp/ci, that is achieved with a pretty high compression ratio as well. The principle works the same for N/A and FI. To get more air out of an N/A engine you need lots of revs and then tuning can be an issue as tuning for pressure waves changes at different engine speeds and you loose this advantage at different parts of the band unless the engine adjusts for this. The same principle works for FI as well, as the efficiency of the turbo changes but we are humans and like to cheat physics so twin charging or compounding chargers is how you beat this with out spinning the engine into the stratosphere.

Or we could say the 13b with a 2.93hp/ci takes the cake, but isn't really a 1.3 now is it? lol
 


OP
S

Siestarider

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Thread Starter #5
Maybe small block v8 was not best comparison. I started my musing with my 50 year old Lotus TC, 95 ci dyno'ed 132 hp when I last had it refreshed. 1.4 hp/ci was strong 50 years ago. That is with Dave Bean cams and ported/polished Webber head at 11:1 compression.

Hybrid DD Fists are making 3 hp/ci. Our new world is just amazing to me.
 


Hijinx

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#7
Maybe small block v8 was not best comparison. I started my musing with my 50 year old Lotus TC, 95 ci dyno'ed 132 hp when I last had it refreshed. 1.4 hp/ci was strong 50 years ago. That is with Dave Bean cams and ported/polished Webber head at 11:1 compression.

Hybrid DD Fists are making 3 hp/ci. Our new world is just amazing to me.
Assuming the theoretical 15% loss, I'm at 5.1 hp/ci. Also with a 5.4 hp/lb it's similar to a Ferrari 458 Speciale. Roll that around the noggin.


Some Guy On The Internet
 


OP
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Siestarider

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Thread Starter #8
Assuming the theoretical 15% loss, I'm at 5.1 hp/ci. Also with a 5.4 hp/lb it's similar to a Ferrari 458 Speciale. Roll that around the noggin.


Some Guy On The Internet
Maybe you meant 5.4 lbs/hp?

Stunning for an economy car in any case.
 


M-Sport fan

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#10
Assuming the theoretical 15% loss, I'm at 5.1 hp/ci. Also with a 5.4 lbs./hp it's similar to a Ferrari 458 Speciale. Roll that around the noggin.
If it weren't for the weight transferring OFF OF the driven wheels, you would be as quick (or quicker) as well. ;) [thumb]
 


Quisp

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#11
Who in 1990 or 2000 even , would believe if you said a 3.5 liter turbo v6 in a full size 4 wheel drive pick up would be running 13.7's and get 18mpg ?
 


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#12
Who in 1990 or 2000 even , would believe if you said a 3.5 liter turbo v6 in a full size 4 wheel drive pick up would be running 13.7's and get 18mpg ?
This reminds me of when I went to the track 6 years ago and first saw a tuned EB F150 run low 13's. My perception of what is considered quick was changed that night lol.
 


M-Sport fan

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#13
This reminds me of when I went to the track 6 years ago and first saw a tuned EB F150 run low 13's. My perception of what is considered quick was changed that night lol.
Yup, let Ford throw one of those in the new, much lighter than an F150 Ranger, and they will have their OWN Syclone on STEROIDS!![crazyeye]
 


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