Author Topic: What is worth it and better at the same time???? (Read 7136 times)

longms · « **Reply #15 on:** November 25, 2007, 04:27:08 PM »

doning atlanta makes a nice supercharger for our cars I hear

gearheadE30 · « **Reply #16 on:** November 26, 2007, 08:34:35 PM »

they do, but not with that spelling. It's Downing Atlanta

. Their kit is actually for the m44 and reports as to whether or not the m42 kit is even in the works are not reliable at all. All it takes is a serpentine belt conversion, but you still have to be careful about predetonation.

sheepdog · « **Reply #17 on:** November 27, 2007, 12:03:52 PM »

Quote from: gearheadE30;38408

they do, but not with that spelling. It's Downing Atlanta . Their kit is actually for the m44 and reports as to whether or not the m42 kit is even in the works are not reliable at all. All it takes is a serpentine belt conversion, but you still have to be careful about predetonation.

The m42 kit does exist, but it seems to be a work in progress.

no1_jazz · « **Reply #18 on:** November 28, 2007, 02:40:48 PM »

Thanks allot to all for the help and advice.

Guys now that I know a 3.91LSD is not worth the doing, a supercharger is the way forward if I want to KEEP the engine (m42) which I do. So shall I just keep the original diff in there and not change it to another?

After installing the supercharger what will I achieve for example would I:

-   Achieve a real good bottom end
-   A good 0-60mph time
-   Achieve a reasonable good top end

Would I have to alter anything else so that the engine compliments the supercharger and vice verser?

Many thanks

Jazz

no1_jazz · « **Reply #19 on:** December 02, 2007, 06:33:27 PM »

sheepdog · « **Reply #20 on:** December 02, 2007, 07:40:02 PM »

Keep in mind we do not spend all day here.

How much you change for the supercharger depends on how much pwer, and how you go about it.

Downing Atlanta has done A LOT of work on this and getting 180hp is not easy. Their kit requires a chip, new brake booster, new A/C pump, new belt system, injectors, manifold and a fuel pressure regulator. It can still run lean. The fuel system on our cars is not up to the task in a blown environment.

Doing it yourself, you may want to look at how they did it, as you may be shocked at what all is involved. Grassroots Motorsports has the article, though I know at least part of it is on here someplace.

The bad side of this is that you are adding a blower to a high mileage engine. A rebuild will cost you a few grand, as does the blower. One mistake and you could easy lose the motor. You may want to look into the Metric Mechanic motor at that point. More power, fresh motor, no blower, stock appearance, stock weight. It is an m3 killer in m42 clothing.

While cost is an issue, you can easily reach the same price and wind up with a hunk of junk that does not even run. Theirs comes with a warranty and their support, which is EXCELLENT. Also that engine can add value to your car. A homegrown setup rarely if ever adds value, and a D/A blower setup will likely not really add any value, though it could add some. Performance builds by reputable places increase a cars value, rather than lowering it like a homegrown setup can do.

You are dumping a lot of money into a car that currently is not worth much, but could be in the future, you should look at it as such. If it is a hobby and you have no plans on keeping it or something, you have options, but if you plan to keep it for a while, do it right.

Another thing to keep in mind is insurance. Once this is done, your car will be worth significantly more. You may want to get better insurance, one with an agreed upon value. This way if it gets wrecked, you can get it fixed. Agreed upon value is an amount set by you and the insurance company that should the car be totaled, you get that amount, not the $2600 the book says your car is worth (even though you have $8k in the engine alone).

Not all insurance companies will do this, and it can cost more.

DaveM-sport · « **Reply #21 on:** December 06, 2007, 01:36:53 PM »

Quote

LSD will only add traction in slippery situations. It does nothing to add power. Basically if one wheel slips, the other continues pushing forward. In a normal diff, the wheel that slips will receive all of the power and spin more, slowing the car.

It has drawbacks in a street vehicle though.
On slippery surfaces, it can cause you to spin. When one wheel spins, power is sent to the wheel with traction, with a normal or open diff, the slipping wheel will get all of the power and the other will get none of little, the car pretty much continues forward but feels like you have lost power, the LSd, will send power to the other wheel, pushing the car out of line, and in a turn can overpower that wheel causing it to lose traction as well. Now both wheels have no traction and you are in a corner, does not take a rocket scientist to figure you will spin.

While many will tell you it is great and is even better for racing, consider that the Lotus Elise came with an open diff and no limited slip option for a while because Lotus found it was faster without LSD. LSD can upset chassis dynamics.

Rubbish in my opinion...

Having an LSD makes a car endlessly more predictable when driving quick, be it on a track or just spirited driving on the road.

It does make the car step out abit easier in wet conditions but it doesn't mean your going to spin unless your abit of a muppet to not react to it.
When it does break loose it will b alot easier to control than if you had an open diff.

The fact that an Elise is a mid-engined car would have had a factor in it not needing an LSD, since the extra weight over the rear would give the car the balance it needs. An Elise can't really be used as a comparison in an E30 needing an LSD or not since the cars couldn't really be any more different.

In my opinion I reckon there isn't any front engined rear wheel drive car that would handle or be quicker with an open diff rather than an LSD.

Racing 2-way diffs such as that used in drifting will have a bad effect on handling on the road alright, but a standard BMW diff that only has around 25% lock in any case will only improve it.

If your after low end performance a supercharger might be your cup of tea.
200bhp is easily enough to attain with doing a good job like one of the 319iS guys on E30 zone has just finished doing to his M42.

Quote

Guys all I�m after is some crazy asss pick off and some quality mid range pick up i.e. if I�m cursing at 60mph in 4th gear and when I put my foot down I want to feel the g force pull me back and the car flying past 100mph after shifting it into 5th of course.

A chip, light-weight fly-wheel, and a few other small things should give you something decent like this since the car should pull in 5th as it did in 4th and 4th as it did in 3rd and so on when it was standard.

No need to shift into 5th though...
A chipped iS is capable of as near as makes no difference 100mph in 3rd;)

hoevesruperd · « **Reply #22 on:** December 06, 2007, 02:56:14 PM »

Quote from: sheepdog;38018

Coil on Plug may get you 1hp, but it is a good upgrade to make as it costs less than good plug wires and lasts far longer.

thats interesting, not really for the power but more for it being cheaper and more durable than stock. i need new ignition wires/spark plugs so might as well, swap it for e46's COP ?? what does that involve? i guess i'll have to machine a plate that will accept the cop insted of the old bmw plastic cover. and what about the electronic, solid state distributor, (not sure of the actual name)
is this a simple tear and replace or do i have to build custom electronic. i can deal with anything mechanical but i would want to risk to build high voltage faulty connections

hoevesruperd · « **Reply #23 on:** December 06, 2007, 03:13:33 PM »

well i got some of my answers here
http://bmw.e30tuner.com/my318is_pic_copcon.php

sheepdog · « **Reply #24 on:** December 10, 2007, 10:34:48 AM »

Quote from: DaveM-sport;39035

Rubbish in my opinion...

Having an LSD makes a car endlessly more predictable when driving quick, be it on a track or just spirited driving on the road.

It does make the car step out abit easier in wet conditions but it doesn't mean your going to spin unless your abit of a muppet to not react to it.
When it does break loose it will b alot easier to control than if you had an open diff.

The fact that an Elise is a mid-engined car would have had a factor in it not needing an LSD, since the extra weight over the rear would give the car the balance it needs. An Elise can't really be used as a comparison in an E30 needing an LSD or not since the cars couldn't really be any more different.

In my opinion I reckon there isn't any front engined rear wheel drive car that would handle or be quicker with an open diff rather than an LSD.

Racing 2-way diffs such as that used in drifting will have a bad effect on handling on the road alright, but a standard BMW diff that only has around 25% lock in any case will only improve it.

Ever heard of drag or friction?

An open diff has near zero drag while cornering.
A limited slip creates some because it is trying to keep the wheels together. This not only can slow lap time but also cause the car to be a bit more easy to spin. Drift guys use a whole list of diffs including ghetto oval track and drag modded diffs... Welded. For the above reason.

As long as the tires do not break loose in corners, the open diff will be the faster diff. Do they always stay glued in place no, but most of the time they do.

The problem is that in high power cars they can spin the tires regardless, and an open diff would just mean one wheel would break loose that much faster. In a momentum car, an open diff is not a problem, you are not nearly as likely to overspin the tires. The higher power can now get on it harder out of the corner, however, cornering ability does suffer some as LSD has been known to create push for the above mentioned reasons, it is trying to spin both wheels at the same speed, which is not desirable in a corner. The tires will then fight each other.

How much is lost is what determines if it is better or not for each track.

Oh, one other thing, an LSD is harder on tires and obviously gas.

The diff should be looked at as a tuning option like spring and shock rates. Not as an all around performance enhancement such as a chip or headers. This is why there is different types of diffs as well as adjustable diffs.