Posted by Zane on January 24, 2000 at 19:41:23:
In Reply to: Supercharger vs Turbo (Long) posted by Wietse on January 23, 2000 at 23:38:03:
So the guy you spoke with said that a 3.5 liter is kind
of shy of the 450 hp range.....Then I see that you need
all these bigger heads and valves, ect. Well, to put it
as example, consider the 1.4 liter BMW Turbo F1 of
the 1980's, this car with a production block went on to
produce 1,400 HP!!! Think about that for a moment. This was
the offical figure, as the dyno at that time didn't go any higher.
It was also said that reliable horsepower was in and around the thousand range.
The driver use to make comments about how the rear wheels kept
spinning in fourth gear...Although a high-tech example, size really has
no bearing on horsepower.
As for turbo lag, it appears that a proper ignition value along with the
proper injector tables coupled with a good cam design---I have better
response now then when normaly aspirated! Turbo lag is a product of set
look-up tables; by today's standards, easily rectified with a progammable ECU.
Who wants to burn chips, anyhow.
As for blowers. With only moderate boost levels, you'll never really know what it "feels"
like in "warp" drive. On the get-go, a turbocharged engine functions much the same
as a normally aspirated engine, in the lower ranges. Again, with proper design a turbocharged
engine can be just as peaky as a normally aspirated engine. The back pressure factor is
just not that great, especially when using a high A/R turbine housing.
Now if you are going to run nitro, well, that's another blower story.....
If I could turbo another vehicle, I'd probably look for a 1.4 liter M12 BMW engine!
: I am thinking about doing something crazy with my e12 and am looking for some advice.
: I want to build a car cable of running the "1 Lap of America" with success. I was looking at building a 944 Turbo or an e36 M3, but something in me says "BE DIFFERENT", beside I already have a really straight and nice e12 with all the tricks.
: I think I have decent combination. I don't plan on winning, just have a great time in a very fast e12.
: My e12 is a great base for this because she is a euro car, has never had any rust, has a fresh full tilt suspension, perfect interior, no AC,PW,PL, 3000 lbs dry. Currently I have 235hp but would like 450+hp.
: To be safe I would install a roll cage for chassis stiffness and full race suspension and brakes.
: I am thinking about building a blower motor. I am a bit torn between doing a turbo using 745i parts or building a super charger engine. I need the groups advice.
: BASIC ENGINE:
: I would use a 3.5 from a 89 or later car because of all the updates including the big valve head and larger intake. I would extrude hone the intake, have the head polished and ported, install forged pistons (CR 8 to 1), piston squirters, balance and blue print the whole thing, include an oil cooler. I would run Motronics, but see if I can get knock sensing ignition to work with it and convert the airflow flapper box to a MAF system.
: Building a TURBO would be easier because I could use parts from a 745i, but after owning a Volvo 850 Turbo, I do not like the turbo lag much. The Volvo is very fast, but very tough to drive smoothly. Maybe it is the small engine (2.3L), high boost, 4 long gears in the transmission, but I don't car for it much. I would run a larger turbo and intercooler and that would just add to the lag. The bonus here is I could control the boost and getting 450 hp should be easily possible. Junk 745i's can be bought for pennies.
: Building a SUPERCHARGER would tough because the fabrication, but I am guessing it will be a much easier car to drive. Getting 450hp could be possible, but according the experts I would run the blower really hard. I would still intercool the motor. I have investigated a number of kits and talked to a couple of different companies and they said 450 hp would be stretching it for a 3.5L.
: Steve Dinan and company were getting around 405hp out of their e34 535i turbos and he had to offer a warranty, so I am sure there is more than 400hp potential there.
: Maybe a dual turbo setup? A number of the late model Toyota Supra are getting 550hp++ from their dual turbo setup, but I question the drivability of these cars and I would have to fabricate a bunch of parts.
: Frank Haas how does that Alpina Turbo e12 drive? Is all or nothing from the powerplant?
: Any advice would be great.
: Wietse