NO 20's ON AN FSERIES PLEASE, these are trucks, not escalades sorry, just had to say that.

i too am convinced turbo would be the best boost maker for a 6, while the supers are better for a v8, just because of the way the torque curves are generally shaped. a roots blower would be nice, but then IMO there more work to do to get it going because of the pully/belt, plus it wont have the higer end hp, which is where the 300 basically sucks at, in reletive terms.

 

I have a good sense of adventure. Unorthodox? Unproven? Down-right Dangerous? GREAT! But can somebody tell me why we insist on running high RPMs? If HP is a combined function of RPMs and Torque, why don't we go to the side of that equation that our engine naturally favors: torque. High torque at low RPMs should be the same as low torque at high RPMs, right? In the end we gear ours tight to turn more RPMs at the tires and the japs gear theirs loose so they have enough power to actually turn the tires. It seems to me that the jap advantage, if any at all, is the result of being geared better for the high end.

If you run quarters at a real track, or for some reason you do all your driving with the pedal down, then high end and turbo are for you.
If you live in the real world though, where driving is stop and go, and the only tree is at an intersection, you don't need that extreme top end... you'll get more use out of the supercharger, which kicks in at partial throttle and low RPM.

Am I right, or did I miss something?

 

You missed something. A turbo can be sized/setup/tuned to operate in any rpm range. You can use a small turbo and have massive low end with no lag, or you can use a large turbo to help the top end. Using it for the low end would be just like using it on a diesel truck. A Powerstroke doesn't have any lag at all and makes lots of torque with a turbo, all with a redline of around 4k rpm.

 

i really dunno now, i been thinkin would a supercharger be better/easier or not. i mean what all is involved with a turbo and what is involved with a blower. i personally am not a fan of turbos. but we have the bottem end to keep up with the boost so im not terribly worried there but what about the SD? wouldnt it mind the added fuel/air? and if i was to add a power adder would i need to upgrade to bigger injectors or change/swap anything else? im not worried about gas milage and all so doesnt matter if it used more fuel. these are all questions id like to find out before i consider even doing this.

 

The question might be "Why not use the RPM we can" instead of "Why not use the torque thats harder to get." Seriously, is ~1700rpm really that high? When cruising around, I shift at 2500, which brings me back to ~2000rpm. When i'm ricing around with my buddy, I shift at ~3600. The motors can handle more RPM, just the stock breathing makes it pretty much useless up there.

T04E 40 trim. 18psi to ~3400rpm while remaining over 70% efficient and keeping that 18psi all the way down to ~1700rpm. Once again, 1700rpm is about as low as you go. This instance would be pure high-torque (though over 350hp at ~3400rpm and over 500ft-lbs at 2000).

Another thing, why does it matter if you're building boost at anything other than WOT. What use is there for it? If you want more power, you push the pedal farther. That way you're getting cold uncompressed air instead of letting slip by hot compressed air. If the compressor was 100% efficient, that would be fine to do, but its not. And the higher the boost, the hotter the air becomes. Also, the engine isn't expending much/any energy on turning the turbo, while the supercharger is taking the full amount of power to turn it.

IMHO, your motor can (on a decent build) handle 5000rpm with no ill effects. Why not use that ability. If you want to bump the boost way up at the lowend to give you more lowend nut, thats fine as well. But to trade away 1700rpm of high boost for ~7-800rpm of low boost at a slightly lower RPM just sounds like a waste. I'm only below 1700rpm in one gear so its definately not worth it to me. And to throw away the natural ability to spin because the japanese build their cars to spin just seems like a waste to me.


-=Whittey=-

 

im runnin an auto if that has anything to do with it. is puttin a turbo on an EFI and dialing it in to run btween 1500-3800 (3800 is shift for an auto) hard? i cant really tear it down cuz i dont have the skills and cant afford massive down time.

 

Some cars such as some of the exotic V12s use four turbos with computer controlled waste gates to reduce lag and make the turbos more flexible for variable load conditions. I know that diesels and aircraft tend to use relatively immense turbos but the don't care about spool up time as the engines tend to operate in very narrow RPM ranges. Ive also noticed that almost all diesels that use blowers (roots type)are two stroke and almost all four stroke diesels are turbos, I hadn't really thougt about it until I was reading the everything you guys were talking about turbos vs blowers. I remember asking some of our mechanics who raced on the side about blowers both roots style and centrifugal as opposed to turbo and they told me that the blowers were not as efficient or flexable for everyday conditions as turbos which is why sme engines like the ford V6s with the little blower on top warn you the engine will overheat if you try to tow with it as belt or direct drive compressors have to be set up more for the conditions under which they will be used.
I have noticed that the little rice racers like to use centrifugal blowers like the paxtons but thats drag racing and they aren't looking for any efficiency at all and those engines don't have to haul three tonnes up Yarnell hill, or the rim. I've thougt a several times though that it might be fun to mount two small turbos with variable and maybe even proccessor controlled waste gates on my 300 and see what its like.