supercharging the 928

[dkkim81]

what are the pros/cons of supercharging the 928s? I think my 928s has only 230 hp, but still hauls. How much better would my performance get? How much worse would the gas mileage get? Could the current parts hold up against the new pressure? Who are the remaining companies that sell and/or install supercharger kits? This would be for daily and weekend driving, not for racing. I was thinking of supercharging it because the current fast cars and seemingly normal cars seem to have so much more hp than my old 928S. For example, even a late model BMW 330i has more hp than my 928S. A late model Porsche Carrerra has 345hp.

BTW, how does the 928 hold up against the 911? Is there even a contest?

[MPDano]

Originally Posted by dkkim81

what are the pros/cons of supercharging the 928s? I think my 928s has only 230 hp, but still hauls. How much better would my performance get? How much worse would the gas mileage get? Could the current parts hold up against the new pressure? Who are the remaining companies that sell and/or install supercharger kits? This would be for daily and weekend driving, not for racing. I was thinking of supercharging it because the current fast cars and seemingly normal cars seem to have so much more hp than my old 928S. For example, even a late model BMW 330i has more hp than my 928S. A late model Porsche Carrerra has 345hp.

BTW, how does the 928 hold up against the 911? Is there even a contest?

For you, Cailf Smog will be your enemy. Unless you don't mind removing all the Supercharger stuff every 2 years.

[Danglerb]

Like Leo said, in Calif the supercharger has to come off every two years for a smog check, which is like a weekend of work before and after each test.

The fuel injection on pre 87 928's isn't suited to more than minor amounts of boost, like 6 psi which would give like 30% more HP, as in 230 goes to 280 to 300, which is about the same as going to Euro parts which sneak through a smog check fairly easily.

87+ the fuel injection brains have good knock detection, and the ability to sharktune (remap the fuel tables to compensate for boost etc.).

Total cost of boost won't be cheap, so I would not bother starting with other than an 87+.

[MPDano]

Originally Posted by Danglerb

Like Leo said, in Calif the supercharger has to come off every two years for a smog check, which is like a weekend of work before and after each test.

Is it really only 1 weekend? After seeing what Carl had layed out on the floor for his Supercharger Kit. I don't even think I could do it in a week. Let alone having to retune it again. If it's just a weekend and that's a reasonable assumption, than friggin slap a blower on that bad boy.

The video sure looks like fun, but I have never personally drove a SC 928 or any car with a SC.

[bwmac]

I would find a way. I never let something like that stand in my way.

[Danglerb]

The "trick" if that's what you want to call it is that you get good at taking it off and on after doing it a few times, and everything doesn't have to come off, as long as 100% of the original smog stuff is still there and functional. Big time sink would be changes to the intake, but no way really around that with some designs and swapping can take a lot more time.

Assuming you start with an 87+ the easy thing would be to keep a spare set of brains with factory chips and swap them, like 15 minutes work, or some use a larger capacity Eprom chip that allows switching between different tunes.

Doing an engine swap, with practice, is easy on a weekend remove and install, and another to swap it back, but might leave a bit more knuckle skin on the engine bay. If my cam turns out too lumpy to pass the smog idle test, I may say screw it and do engine swaps.

[dkkim81]

Maybe a supercharger would be good after the car become a "classic" so that I won't have to smog it...isn't that your car coming up soon MP Dano? BTW, you know of any shark owners in Laguna Beach? I keep seeing a clean-looking and shiny black 87 or 88 shark. I saw it parked on PCH the other day. We pushed our sharks for about a minute on the 133 freeway/highway a few months back. Good thing he slowed down cuz the cops were stopping a whole bunch of people on the side.

[MPDano]

Arnold put a stop to that a few years back ('05?), so the oldest car that will not need smog is 1975 (I think). Yeah, mine would have been in that category next year, but not anymore. I think Mike (DanglerB) might know more than I would since he lives in Orange County. I way down south in San Diego.

[bwmac]

Can you not leave it in place and just turn down the boost, adjust A/F for a clean burn and meet the standards? Is it about clean air or is it about mods?

I was always told that a SC makes your burn more efficient.?.?

[MPDano]

Originally Posted by bwmac

Can you not leave it in place and just turn down the boost, adjust A/F for a clean burn and meet the standards? Is it about clean air or is it about mods?

I was always told that a SC makes your burn more efficient.?.?

Negative. We have a visual on all our Smogs. They break out the flashlight and look in the engine compartment as well as under that car.

[bwmac]

Originally Posted by MPDano

Negative. We have a visual on all our Smogs. They break out the flashlight and look in the engine compartment as well as under that car.

So its not just a smog law but a change from stock law. That sucks. Just another Gov BS law because if you could make it better or cleaner with a SC and water injection why wouldn't that be excepted? There again through dictation they force people to lie and go around the law and then they wonder why nothing changes.

[laneyamps]

Way too expensive, especially for a car from the 1980's. For $6000, I can buy another 928! Install a new exhaust system (with headers) and you'll gain a really nice amount of extra HP. Maybe not 100HP (like a Supercharger will yield), but at least 50HP!

I noticed a huge difference with my new exhaust system.

[Danglerb]

Headers and exhaust aren't going to add 50 hp unless the engine is some totally modified hot rod cranking out 350+ on its own. On a stock early 928 its going to be MAYBE 20 hp.

The big club of the Calif smog law, maybe the federal part, is the non tamper clause. That usually means alter nothing between the air meter and the cats, but before the air meter and after the cats its a free for all. In theory you could put in a boost system, leave it in, and bypass everything back to stock for the smog check.

[bwmac]

NOS is cheep
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NITROUS OXIDE ( nos / n2o ) advice forum • Index page

[sonett3]

TT that car

[bwmac]

Turbos are an incredible performance enhancement as well.

When chev added the turbo to the (Grand National) that little 3.8L came to life and would eat hot rods with big blocks in them.

The repairs that I had to do to them were Oil leaks due to the high crank case pressure due to blow by, and the heat melted everything close.

My problem with turbo systems is only the added heat under the hood and the minor part is the lag that some systems have, other then that, its a great enhancement.

Super charging your car (in my opinion) achieves the same result without near the heat and zero lag.
I would never dicker one over the other because they are both great systems and are ment to be installed and enjoyed.

NOS (IMHO) would be a better option for the guys that have to deal with state laws because it can be uninstalled, easier.
They can then get the smog check done, go home, reinstall there NOS and go blow the doors of some vet all in the same day.

The turbo and the supercharger are systems that have a different feel and both have pros and cons.

If I had the cash i would have to think long and hard but due to the changes in the SC world in drivability and tun-ability, I would lean that way.

The Roots type blower is a serious system and thats why top fuel pros use it.
The centrifugal SC is the answer for smooth but kick your A$$ power

The Turbo is the (back in the day) smoother increase in power adder which is why the industrial world uses the turbo on everything, but as I said above, the centrifugal system can be a very friendly system.

I am not a pro in any of these areas, just a mechanic that has had to deal with them over the past 20 years.

Oh, what am I going to use, ... NOS because it is cheap and if I decide that I want a SC or Turbo down the road, its not a waste of money that will sit in the corner.

[MPDano]

Interesting. Us Calif Guys are interested in the NOS Setup. How hard is it to install and uninstall. This is something I may go for after my next smog check at the end of the year. Costly?

[Danglerb]

Take out 400 lbs of stuff a hot rod doesn't need, put on a good exhaust and intake, the biggest cam, and the most cubic inches you can afford, and a 928 doesn't need any power adders, just a place to race.

[bwmac]

Originally Posted by MPDano

Interesting. Us Calif Guys are interested in the NOS Setup. How hard is it to install and uninstall. This is something I may go for after my next smog check at the end of the year. Costly?

In canada, about $300 to $1500 or more depending on what you want.

What you don't want is a cheap system that turns on full power (150-300)HP in a BANG, that destroys engines, transmissions, and diffs.

From what I have heard, and the videos I have see, the new systems use a ECM (controller) that monitors fuel mixture and brings the power on in a ramped increase.

Go to U-Tube and search 928 nos

[XLR8928]

Thank God no one on this thread suggested an american engine swap. Just bad form IMHO.