hey guys, looking to upgrade my diff. i have a 2003.5 i was thinking of changing my diff to the quitfe vlsd any opinons?

 

quick question, do u think a rear diffuser would look weird on a stock exhaust?

 

I drive an' 06 G35 Coupe. I'm about to buy a spacer but I'm wondering if there are any prereqs for this. What is an MREV or an MREV2 and do I need either? I have a limited budget so if I can get just the spacer that would be best.
Thanks!

 

This is the sedan section, but yeah...

And there isn't any prereqs for the spacer, you can just install it and your g2g. The mrev2 works best if you have the revup motor(the 6MT). So the answer to your question is yes, just the spacer would be fine. And depending on where you live, it would be best to get the isothermal or copper isothermal spacer if you live in a colder climate.

 

^^^^ note about the Plenum spacer, there is a hidden thing u need to do with it most of the time is a tune up, the spacer will most likely make u run a little lean... or rich... cant remember lol and as such u will need a tune up for the car... just an FYI

 

To see the full benefits of the spacer, you need a tune. It's not worth it though. $200 spacer and a $600 tune? Not likely that I'd spend that. Install the spacer and enjoy. When you have the cash to dump some more power adders, then tune to benefit from the complete package.

 

An actual "tune up" or a "tune"?.....but yeah, a tune up would seem logical since the amount of air will change how the fuel is burned.

And +1 on the tune, but thats when most of your breathing mods are done, intake, spacer, exhaust, etc....

 

A tune is not "logical". The mass airflow meter is forward of the intake plenum. It still meters and moves the same amount of air. So it tells the fuel trim the same info no matter whether there is a spacer or not. On the other hand, the principal benefit of the spacer kit is to isolate the upper and lower plenums from each other to reduce intake air temps. The reduction in air temps (I'm uncertain exactly how much of a reduction) can affect air density. Denser air allows for more power. From all I have read on here, the immediate improvement nets 10 or so horsepower by simply installing it. A tune might net you another dozen ponies. To me the cost benefit of a tune simply for that mod is not wise. However, running HFC's, cat-back systems in line with any intake mods such as a Z tube or spacer will be more cost beneficial to merit a tune.

 

^Good to know and thanks for the info, and sorry for the noob comment then lol

 

Oh! Didn't notice it was in the sedan section. I was desperate for an answer so I just googled something random about spacers. Thanks for the reply though!

Also, I live in San Diego so the weather is generally above 60 year round. Should I aim for the Isothermal one? 5/16 or 1/2? What do you suggest? I've heard all kinds of stories...

 

From what I've read, the isothermal helps with the heatsoak, but if your on a budget, the basic will be just fine. And if your not going FI, the 5/16th will prob be the best.

 

5/16" is the most commonly used size. The Iso-thermal would also work well in SD. You don't need the copper Iso-thermal though. The Iso-thermal has a valve in the kit to allow for you to stop the coolant flow to your throttle body. That helps also cool your air charge. The spacer by itself is for the budget builder but the Iso-thermal is ideal for most applications. Not sure of the benefits of the 1/2" over the 5/16" but I've read that it won't fit under the stock engine cover and if you have a strut tower brace, it won't fit under that either (if I remember correctly).

 

Everyone's a noob at some time or another. Hell, I'm still a noob in most respects. Most of what I just spit out right now was stuff I gleaned off this site.

 

By that logic, no mods would change mass airflow readings, because they are all behind the meter. But that isn't true. If the efficiency of the engine is increased (such as plenum mod or aftermarket exhaust) the engine will be able to draw in a larger mass of air.

If the primary benefit of the spacer was to reduce air temp, then we wouldn't need a spacer, an iso thermal gasket would do the job. Also, the size of the spacer wouldn't be critical.

 

Still wrong. For instance, stock exhaust and stock intake tube moves x amount of air because of the restrictions based on the diameters of the tubes. MAF reads that amount and adjusts fuel air to work according to the program. As well, the engine can only pull in and push out so much air based on that restriction. You change out the entire exhaust - headers back - for a larger diameter but leave the intake stock. You will maintain the same amount of air pulled in to the motor due to the intake diameter but the engine can push out more of the burned fuel and air mixture after combustion due to the lower restriction caused by the exhaust. Now change the intake tube to a larger diameter with less bends to match with the new exhaust and the engine can breathe better both in and out. You still run in to a limit of how much the engine can take in due to displacement, but with less restriction pulling air in and pushing air out means it can move more altogether. Therefore, the MAF will again detect that change and adjust fuel trims accordingly. There is still an overall limit but there will be an improvement.

Another example. On a boosted application such as superchargers, the MAF is before the SC (roots blower). The MAF reads the air at idle as normal atmosphere. When you throttle the car under load (in gear) the SC multiplies the air density by force feeding the air into the motor. The motor isn't pulling the air in; it's being crammed in. So your intake will be asking for more air from the SC. The MAf sees that and richens the fuel mixture to match the amount of air going in to the motor.

In N/A apps like our motor, the spacer does little for overall volume. Do the math with the thickness of the spacer by the width and length of the plenum. I'm no math whiz, but that doesn't provide a significant enough increase in volume to do as you state happens. The following is right from Motordyne's site:

"The new Iso Thermal system combines our aluminum plenum spacer with thermal management components that substantially reduce upper and lower plenum temperatures. Cooler intake air temperatures increase air density, reduce the tendency for detonation (ping) and that increases engine power.

The first component is an Aramid thermal isolating gasket that is installed between the lower plenum and intake manifold. By installing the Iso Thermal™ Aramid gasket between the intake manifold and lower plenum the heat transfer is significantly reduced and both the upper and lower plenum assembly run at much lower temperatures.

The second component is a throttle body Coolant Control Valve (CCV) that allows you to heat (or not heat) the plenum assembly. With local weather temperatures below 55’F the valve is left open. In warmer weather the valve can be closed for maximum performance benefits.

The third thermal management component is the new Iso Thermal plenum internal supports. The plenum internal supports are self retaining and self sealing."

They clearly state that the gaskets do the work of isolating the block from the lower plenum and the spacer isolates the lower and upper plenum from each other to limit heat transfer. Base your own judgment from this. If you haven't done this mod then you wouldn't know that the aramid gasket on the spacer itself is glued to the bottom and top side of the spacer. These aren't your ordinary cardboard gaskets.