Supercharging

[Germanik]

Hey all,

I'm the owner of a 98 Z3M roadster with 82k on the clock that I'd like to hang onto it for at least 5 more years before the wife and I start having kids. I've looked over power mods, and while the M50 swap sounds nice as I hate the lack of high RPM power in this car, it just seems like too big of an investment for too little return. I'd rather just get the VF supercharger and be done with it. If I go this route, what sort of supporting mods would I need?

Two years ago I had 3 different shops inspect it and all came up with the same $7k repair bill and said the rest of the car, particularly the engine, was in great shape. Things that got replaced were the clutch, shocks, oil filter, starter, brakes, battery, radiator hosing, and a number of other basic parts. It also has new Pilot Super Sports with around 2k on them.

Thanks

[BimmerBreaker]

Just buy a kit, they are pretty inclusive. Make sure the cooling system and everything is still good, should be after 2 years but worth checking

Subframe reinforcement would be the only major thing

[Randy Forbes]

You may want to make sure something like this doesn't happen:

[bubbafett]

Randy Forbes No doubt a supercharger puts lots of stress on the subfloor, and your kit is bullet proof. But what do you think the odds are of supercharging without needing to upgrade the subfloor? Reason I ask is I'm about to find out for myself...

[Terry F.]

1.9s fail too. I would want to reinforce an FI car pretty quickly. If you don't bang shifts and apply throttle sanely, that helps the subframe a lot.

Terry
Note 8/Tapatalk.

[Germanik]

Thanks for the replies.

I figured the subframe reinforcement would be the first thing to address. Tomorrow I'm gonna call some shops around the state and get quotes for the install.

Unfortunately, I still have to get my hood dents removed, a new rear window, a new windshield, a new glove box, and replace the damn seat belt guides.

How about exhaust systems?

[Terry F.]

You like loud or LOUD or? Budget?

Terry
Note 8/Tapatalk.

[Germanik]

I'd say loud with no drone. Not cheap but reasonable.

[Terry F.]

Ok, I'll let the forum work with that.

Terry
Note 8/Tapatalk.

[z3forlife]

If you go the vf route then be prepared to source a different tune. Their tunes have ran rich in the past and cause hard/no start at elevation as several of us have found out. You can get help with that on this forum

[Mr Bingley]

Based on personal experience, be sure to replace the engine and transmission mounts when you add a supercharger. I would recommend adding oil cooling--I did and the oil runs at 200 deg. when hot supercharged--it used to go to 240 NA. I myself would not add 100 HP or so without reinforcing the subframe/trunk floor/differential mount system (RF Kit). As a "while you're in there thing," replace the cyclone oil separator (crankcase breather) system. It would be a good time to preventatively replace the power steering hose that will eventually need to be replaced anyway. This would be a very good time to upgrade the cooling and suspension systems. Also not a bad idea to address the driveshaft wear parts (giubo and hardware, carrier bearing, lube splines and nylon nut)--you're going to have to anyway, and this way they'll be up to the task. Do yourself a favor and replace the alternator (or have it rebuilt) before you pay a bunch of money to mount a supercharger on top of it--it's kind of hard to get to afterwards. If I was you (and I was in this regard) I would ship it to Florida and have Randy install his kit--it will be well worth the added cost of shipping, and he has a shipper at a very good price.

For what it's worth, it would be less expensive to leave the M alone, and just buy another more powerful car if you're looking for power. Also for what it's worth, supercharging does add more power, and significantly so, but you will get used to that, and it will still be under powered compared to today's cars off the dealer's lot--i.e., with or without a supercharger, a Dodge, Ford, Chevy, or even a pickup will still leave you in its dust.

[s8ilver]

Their tunes have ran rich in the past and cause hard/no start at elevation as several of us have found out.

I found this out the day after I bought my car (Hawaii car, so PO would have never known...I'm guessing you might never realize the issues in SC either). We drove the car home from Long Beach to Denver...our quick lunch stop in Vail turned into several hours as the car cooled down enough to restart. All sorted now, including the sub frame kit (my spot welds were just starting to go at 52k miles, 5k of which were FI).

[Germanik]

Thanks Bingley.

Your post reminded me. The PS hose, the oil filter stand, and multiple drivetrain parts (flex joint, output shaft, and a couple other rubber pieces) were replaced due to excessive wear two years ago. The suspension has had the struts replaced with Blisteins and they are mighty stiff. I wanted to add a drop and sway bars because the body roll is excessive for how stiff the car rides and how griptastic the tires are.

Where in Florida is Randy located? I am actually only a couple hours from the border myself so driving may not be out of the question. I hear you on the American muscle. I drove an '06 GTO before selling and getting the M at a significant bargain. I had invested about 5k into the suspension as it was a pig on the road, and beefed up the engine to just under 400 wph. It was a monster but no amount of money thrown at the suspension fixed the fact that it was designed to do one thing well only-- go fast in a straight line. It's nice to have a car that handles well, but in one that is 3,800 lbs... it will never drive like my M. Fortunately I live in the South so getting rid of a well cared for GTO at a high price was the easiest thing ever.

I've thought about ditching the M in favor of something new since it is a '98. I just hate nearly every car out there nowadays... The M is so classy and still looks new 20 years later. Plus it's so raw. It's uncomfortable, you feel every bump in the road, and any input to the wheel and the car wants to fly off in another direction... I love that.

[deni2s]

I've thought about ditching the M in favor of something new since it is a '98. I just hate nearly every car out there nowadays... The M is so classy and still looks new 20 years later. Plus it's so raw. It's uncomfortable, you feel every bump in the road, and any input to the wheel and the car wants to fly off in another direction... I love that.

I feel you And probably you will not be able to do yourself on new more powered cars as much as on Z3. So your M will be still going strong, when new, more powerful plastic crap cars will be in the trash

What about clutch, shouldn't that be upgraded when going SC?

[Jamesons Viggen]

The supercharger and M50 swap(headers too) all work very well together. The blower doesn't stop making power as revs build, in fact I would love to upgrade my valvetrain so I can rev closer to 8k. So I would not skip the M50 which is cheap in cost and DIYs are readily available. I even did my own install.

[Germanik]

I'm not sure on the clutch.

As mine isn't yet at the 2 year mark I'd probably just keep it in until it blows from the power then replace it with a heavier one.

James,

Maybe in that case I should go ahead with the M50 before the supercharger. That way I will have a couple steps up in power to adjust to. What else other than exhaust would pair well with the M50?

[Jamesons Viggen]

I'm not sure on the clutch.

As mine isn't yet at the 2 year mark I'd probably just keep it in until it blows from the power then replace it with a heavier one.

James,

Maybe in that case I should go ahead with the M50 before the supercharger. That way I will have a couple steps up in power to adjust to. What else other than exhaust would pair well with the M50?

My car came with a SuperSprint catback. Basically, most of the name brands are of good quality. I would try and listen to some clips or better yet find someone local and hear the setup in person.

[BimmerBreaker]

I'm not sure on the clutch.

As mine isn't yet at the 2 year mark I'd probably just keep it in until it blows from the power then replace it with a heavier one.

James,

Maybe in that case I should go ahead with the M50 before the supercharger. That way I will have a couple steps up in power to adjust to. What else other than exhaust would pair well with the M50?

If you want to do the M50 manifold before F/I, I'd pair it with a BBTB and bigger MAF and all the bolt ons that people run with those to make use of the extra volume. Otherwise it will just shift powerband. But if you do the M50 plus BBTB and all that stuff now, it will be ready for the S/C when the time comes.

[Mr Bingley]

Randy is outside of Tampa. Email him (erandyforbes@aol.com)to start a conversation--he recently indicated a desire to wind down his install practice in the near future, but I'm guessing he's still taking clients at this point, so don't put it off. Having Randy Forbes install your subframe kit is like having Carroll Shelby tune your Mustang--take advantage of the opportunity while you can.

[E.Hands]

Randy is outside of Tampa. Email him (erandyforbes@aol.com)to start a conversation--he recently indicated a desire to wind down his install practice in the near future, but I'm guessing he's still taking clients at this point, so don't put it off. Having Randy Forbes install your subframe kit is like having Carroll Shelby tune your Mustang--take advantage of the opportunity while you can.

-this +10

[rf900rkw]

The *volume* of air is determined by the engine mechanicals; displacement, cam timing, etc. The blower doesn't cram more air in, as is often precieved. It merely increases the density. Thus the minor gains and large losses of the M50 and other mods translates almost exactly to a supercharged car.

[Germanik]

The *volume* of air is determined by the engine mechanicals; displacement, cam timing, etc. The blower doesn't cram more air in, as is often precieved. It merely increases the density. Thus the minor gains and large losses of the M50 and other mods translates almost exactly to a supercharged car.

So you're saying to add an M50 in addition to a supercharge isn't worth it?

How about exhaust? I looked up SuperSprint and a full header back exhaust is just at 4k shipped, which more than I was looking to spend. If it's of no benefit to the FI, I really don't care. I just want to get a list of everything needed/synergistic with the Supercharger.

Will definitely be sending Randy an email, thank you for providing that info.

[Jamesons Viggen]

So you're saying to add an M50 in addition to a supercharge isn't worth it?

How about exhaust? I looked up SuperSprint and a full header back exhaust is just at 4k shipped, which more than I was looking to spend. If it's of no benefit to the FI, I really don't care. I just want to get a list of everything needed/synergistic with the Supercharger.

Will definitely be sending Randy an email, thank you for providing that info.

BUY second hand. I got about $15k worth of my blower setup(retail) for $2k. I then showed a gain of 150whp on the dyno.

[rf900rkw]

The M50 does the same thing on a blown motor as NA. big hit in the middle for a little gain at the very top. Exhaust, on the other hand, will make a big improvement. Exhaust, like the MAF, are not in the high density area and therefore must deal with higher flow volume.

[zellamay]

The *volume* of air is determined by the engine mechanicals; displacement, cam timing, etc. The blower doesn't cram more air in, as is often precieved. It merely increases the density. Thus the minor gains and large losses of the M50 and other mods translates almost exactly to a supercharged car.

To clarify: at a higher density, as is the purpose of FI, with the same volume, there will be more air in the cylinder. The dynamics of: mechanical parts, timing of ignition, cams, etc., length/size of intake, etc., that are optimal for an N/A engine should be at least a little different than for a FI engine, due to the very different density/volume of the air being pushed into the cylinder.