FI Technical Discussuion to End All!

(EDIT by Grippy) OK, I didn't want to see this one go down the ditch so I am bringing it back.....

Premise:
Lets talk about the pros and cons of each FI power adder. Let's see facts and forward thinking, This is not meant to be a bash on ANY power adder...any direct hits at ANY manufacture that do not have facts to back them up will be deleted. Have at it folks.....lets see the knowledge, lets talk about what might and might not work, tell us what you know, share your experiences, and lets keep this one respectful and proper when discussing our different views


NOTE: I will be merging the old thread with this one as I clean it up.

 

Thanks for bringing it back. I don't have enough engine knowledge to post anything here, but I was reading the first one everyday trying to learn something which is what I think it was about.
Thanks again
Mark

 

Are you going by brand or type of FI? ie: Vortech vs. Procharger OR roots vs. centrifugal vs turbo etc.

 

your call, you can talk by type or brand

 

STS is the best. Discussion over







j/k I think that we need to figure out what we are going to actually talk about. The other thread was all about flow charts and there wasnt any basis for what we were talking about. I think it should be based apon engines. What is the best for the 4.8, then whats best for the 5.3,5.7,6.0 and so on. Thats just my 2 cents.

 

I would say let's start with pros and cons of type or brand. Then if we go beyond that we should base discussions on basically stock 5.3l's since that's what most members have. Once you go past that with larger disp, trans, heads, etc, it becomes less relevant to a someone just gettting started in FI.

 

Well I have had a Whipple on my 5.3 and I really liked the On demand power!!

The intial torque curve and power band were awesome!!!

I also feel (in my own opinion) that the power of a supercharger is all through the rpm band!!

The power is probably less than intial on off the line, but the whipple was still making alot of power up top!!!

I think we should discuss engine size to best application of FI!!

as in

5.3 whipple, STS, Vortech, Procharger- Pro's, Con's, Opinions, Experiences, etc

 

I don't understand why engine displacement has anything to do with it. Lets try and stick with what the moderator said, Lets talk about the pros and cons of each FI power adder, and see how far we get.

Unfortunately, I can't add much to the discussion though because my first-hand experience is limited. (some Buick V6 turbo work & Chevy V8 draw-through carb applications)

I've got an '02 K2500HD w/6.0 V8 and would love to boost it but I'm not willing to pay the asking price. So in other words, PRICE is a big con for me.(for both systems)

If I were to do it though, I'd pick turbocharging mainly because I like the 'free' horsepower. And if it was designed right, it could be easily removed if I ever had to pass a DEQ inspection. (assuming stock exhaust manifolds were retained)

Both approaches (turbo/supercharging) require fuel and ignition changes but those problems seem fairly easy to fix with PCM reprogramming and injector upgrades.

It seems as though the biggest differences between a turbo and centrifigal or roots style supercharger lie in the exhaust. A turbo requires more plumbing changes while the alternative does not. (is this a pro or a con?)

OK, I think I've climbed out pretty far on this limb. Anybody ready to cut it off?

 

I have a 4.8 with the RADIX. Pulley size is 3.7". Max. boost is about 7.5 to 8 psig. Dyno went from 240 rwhp to about 315. Replaced Flowmaster 70 with Magnaflow and it seems to help, but haven't dynoed since. Read the other day that intercooled systems can dyno substantially lower than what they deliver on the street. Seems the lack of airflow through the intercooler radiator causes IAT's to rise sharply, resulting in pulled spark timing and lower power. Any confirmation?

Anyway, the reason for my choice was that I wanted a positive displacement FI system for good low-end torque. Although twin screw units are better on paper than roots blowers, my survey of vendors revealed that roots blower vendors had better overall systems, and better customer support. The STS turbo was not out yet, but one concern I would have had is water ingestion from all our rain. I have been very pleased with the radix, as it provides the desired low-end power, and yet the vehicle has none of the quirks and idiosyncracies that come with most high performance mods. Save for the howl, an unknowing driver would think the truck had a 454 rat motor, until (s)he saw the 19 MPG fuel economy . I hope this is close to what you are looking for.

 

It will come down to what workes better for each person. Everyone has a different goal, along with that is a tolerence to certain things that come with hp. Some people can tolerate more drivability issues then others.

For a person that want drivability something like a Radix owns. Not just Radix either....
Big torque means you can still tow and there is no need for a really high stall converter to get into the "powerband". So with this you get lower trans temps and better everyday drivability. Allthough the early boost with a 1bar sucks for mpg, going into open loop at 35-40% is not completly ideal. You sort of learn to drive like a two step if you want mpg while being stuck with 1bar tuning.

Next the centrifical. Sure it can make more power then the positive displacement blowers offered for the trucks. No I did not say more then all positive displacement blowers either. Along with this comes a power band that comes in a little higher in the rpm range though. This is because the blower is RPM dependent for boost pressure. So now you have a higher stall converter to take advantage and higher trans temps and drivability issues. Now of coarse you need or want more rpm, cause rpm equells more boost on this type of blower. Also moving the rpm higher does not affect the IAT's as much as most positive displacement blowers in this arena. So you get a lot more power with that big cam. Where a "Radix" does not need or even benifit from a huge by big cam. Now with the big cam you will want even more converter and now you have more drivabiliy issuses to go with it. Personally I can deal with it if I can blow right buy the Radix guy. But you have to decide weather or not this is what you want.

Now into turbos...arguably the ultimate power adder. It can produce gobs of torque and hp that is just totaly insane all the way through the power band. Also with the right turbo selection power can be made allmost everywere. Allthough when it comes down to really big power and super fast quarter times lag will become a issue. this is because of the larger compressor and exhaust housings needed to sopport more power. These make spool up take longer (the amount of time and rpm needed to start making boost up to full boost). Now you are back into a high stall converter that will take away from drivability. Allthough you can build one insane machine this way. Just depends on what you want. Also being able to turn up boost from in the cab can be a good or bad thing. Towing is almost always a bad idea with most of the kits I have seen as too much underhood heat will be generated.

I will edit later as I am out of time lol, just some random thoughts I thought I would post for you guys to chew on.