Top mount vs. Bottom mount

[Arrow]

Are there any advantages/disadvantages to going with either a top mount or bottom mount? I searched but didn't come up with much. I'm just trying to figure out what setup to look into before I start collecting parts (which is a ways away... but it's better to know now then later). And do you need different turbos for the different manifolds? I know that the turbos have oil fill/drain lines and I'm not sure if that plays into it at all. I know that a bottom mount setup might interfere with the steering rack or the fender well... but wouldn't you also have shorter IC Piping? I don't really know and am just trying to find out some people's ideas and knowledge! Thanks in advance for your replies!

[KATwo40]

Top mounts are better IMO because:

1. Easy access to oil lines and pipes

2. Easier to fit a larger turbo and ext. WG.

3. Most KA top mount manifolds are a T3/T4 footprint, whereas most of the bottom mounts I've found are T25/T28.

Bottom mount is better because:

1. Easier to fit a downpipe

2. ?

3. ?

4. ?

That's about all I can think of.

[SoCalS14]

Bottom mount is better because:

1. Easier to fit a downpipe

2. ?

3. ?

4. ?

That's about all I can think of.

Little more stealthy???

[Arrow]

Thanks for your reply! I have thought about possibly custom building one... Idealy it would be nice to have an equal length manifold... but in reality I might not be able to fabricate one and it might also just be cheaper to buy a manifold... I wasn't sure if there were any performance benefits to either setup or if a bottom mount would be better on the aspect of keeping heat away from the brake booster or that stuff.... Just some thoughts though... Keep opinions coming please!

[virus77]

Top mount looks cool, it drops peoples lower jaw when they see the snail chillin next to the motor. As long as you have some form of heat wrap around the MC it shouldnt be a problem. Either one is good though, its jsut a matter of taste/opinion.

[Arrow]

Does anybody know if the type of turbo used would matter in either top or bottom mount? I'm not too familiar with the different setups. As far as I know the only limiting factor is the size of the turbo...

[virus77]

It depends on where the flange is on the manifold. There are certain top mounts (revhard for one) that wont fit anything except on center turbos (T4). Also some ABS equiped cars dont fit those ebay ssautochrome manifolds. So it does matter what type of manifold you use with a certain turbo unless you are making your own, in which case you can work things out hopefully.

[cosmo]

Bottom mount is better because:

1. Easier to fit a downpipe

2. ?

3. ?

4. ?

That's about all I can think of.

2. Lower underhood temperatures3. Not as obvious as to what your'e packin4. More selection

[Arrow]

2. Lower underhood temperatures3. Not as obvious as to what your'e packin4. More selection

More selection? Would you mind elaborating some for me by what you mean in more selection. Like more selection for manifolds or turbos or both? Thanks a lot guys!

[crzycav86]

The z31 turbo can't be fitted on a top mount manifold thanks to the way the internal wastegate exhaust housing was designed..

[Toahk]

The z31 turbo can't be fitted on a top mount manifold thanks to the way the internal wastegate exhaust housing was designed..

If you run a blockoff plate and an external WG you can run it whichever way you want.

[saintsinner]

well from experience with my sisters car,the turbine side doesnt clear the master cylinder,so an adapter and such was made to position the turbo further forward in the engine bay

[Arrow]

It seems that there are a number of KA-Ters that use the Z31 turbo. What are the stats on it? I was thinking about either that or a T3/T04 50 or 54 trim... I want something affordable and something that will be good to around 250 wheel... which any of the above should hit to my knowledge. I also want to try to get the best economy that I can out of the setup . Thanks for all of the info guys!

[sil80drifter]

screw top mountscrew bottom mount

side mount is what fits best for all SOHCs and probably DOHC if you move the PS tank out of the way, it clears the brake lines, the master cylinder, etc ect etc. it's easily accessible and good for weight distribution (compared to top mount) and potential hood clearance issues. And it's pretty stealthy.Take a look:http://public.fotki.com/sil80drifter/turbo_process/

yah. thats right. sidemount rules.

sil80
Modified by sil80drifter at 12:09 AM 2/17/2005

[Toahk]

sidemount does rule. Rock on sidemount, rock on.

I run a z31 turbo btw.

[Arrow]

Wow, thanks for the input! I really didn't know that side mount was a possibility. It seems to have many benefits... the only thing that I might ask though, has anyone tried an equal length side mount manifold??

[sil80drifter]

Hey Toahk, consider relocating your coil to the left and down, where that empy bracket is, right now it's kinda too close to the turbine housing, and you don't want the coil to get too hot. All the wires should reach, they did for me

As far as EL goes, I've never seen an EL sidemount because... well so far they all have been manually fabricated by peeps like us, or bought from Gladman Performance (e-bay for aorund $250, good deal if you don't have a welder). Hopefully soon they will start coming out with EL sidemounts, but for now they don't. Not that it would matter much unless you're pushing some rediculous numbers and the log manifold's flow is in your way to more HP.

sil80
Modified by sil80drifter at 2:08 PM 2/18/2005

[Arrow]

I'm not looking for sick amounts of power. Like I mentioned before around 250 wheel would be enough for me. But I was just thinking that an equal length manifold would have more consistant power delivery throughout the RPM range (which might be true, but it might not be enough for me to really worry about it)

[bradd]

Well if you only want 250 @ the wheels then a log style should be just fine.

As far as long tube headers go, I have made bolth (if you take a look at my link) I found that its harder to make a bottom mount equal length. If you can find me a pic of one fot the KA I would like to see it. On a top mount you dont have a ton of room for the down pipe, that is why I went to a bottom mount... to fit a 3.5" exhaust from the turbo to the tail pipe. As well you down pipe wil not have as many sharp 90deg bends in it you might just have two 45degs to get beside the transmission.

http://www.nicoclub.com/zerothread?id=102233

[Red-KAT]

2. Lower underhood temperatures3. Not as obvious as to what your'e packin4. More selection

2. Have you tested this?3. You drive around with your hood open often? weard...4. Maybe...

[Toahk]

Quote »Hey Toahk, consider relocating your coil to the left and down, where that empy bracket is, right now it's kinda too close to the turbine housing, and you don't want the coil to get too hot. All the wires should reach, they did for me [/quote]I'll do that. My wires came with an extra long coil wire, it should reach.

2. Have you tested this?3. You drive around with your hood open often? weard...4. Maybe...

3. As far as the police go, a bottom/side mount turbo almost looks stock imo. If I cleaned mine up some I could pass it as a stock turbo engine. As opposed to a big snail chillin right up top in all its glory. 4. I dont know about more selection, but I def have plenty of clearance all around with my sidemount turbo.

[Arrow]

Yeah I'm digressing for a bit.......

Toahk and any others that are running the Z31 turbos, about how much power are they good for and what rpm does your full boost level kick in at (whatever boost you have yours set to)

[Toahk]

It boosts between 2-3k and gets full boost pretty quick. Im running 9psi at the moment and I think someone said they max out at like 14psi and are still efficient. Im not sure, but its plenty of power for what I need right now.

[Arrow]

More digression....

Toahk, do you use your 240 as a daily driver? If so, do you know what mileage you get in the city w/ your turbo?

Back on topic....

Now that I'm thinking about it a side mount seems to be a good idea.. or at least something close... If I was to fabricate one myself, I might have it a little lower than your side mount to get a shorter dp and possibly make it look like it was there from the factory... might turn out neat... but if I don't do that, where did you guys get your side mount manifolds (or bottom mount)... I've found a lot of "DE" manifolds but I haven't came across too many "E" ones.... Thanks again for all of your help!

[sil80drifter]

most sidemounts (actually all except for the gladman racing one) are made by people themselves. You buy a flange from JGS or another place that sells head flanges, and buy some 90 degree mild steel bends from an online hardware store (can't remember the name right now), and weld it, or have it welded.

sil80

[KATwo40]

Hmmm, interesting.

I've never needed to be stealthy about what I'm packin' under the hood, since we don't have Nazi's here in TN for police, and if someone wants to know, I just don't open the hood.

As for more options, I doubt that seriously. With the vast array of turbochargers available today, you'd be a complete failure as a person if you couldn't find a rediculous amount of turbo options based on a T3/T4 footprint.

Sidemount: That's an interesting idea. However, how can this balance the engine anymore than a topmount or bottom mount? If I'm not mistaken, the further outward a weight is placed, the more leverage is has, applying more stress to the base at which it's attached. Besides, if you want a tubular manifold for the most efficient flow, forget the sidemount. I don't see that happening. Not that log manifolds are bad. There are a lotta high hp log setups goin' out there. Plenty to school my little pavement slapper.

Underhood temps: I don't really see how you're lowering the overall underhood temp, since the bottom mount is tucked under a gob of pipes and still doesn't get much airflow. A well placed scoop in the hood or some decent turbine wrap can easily displace the heat. I'd go with a turbine wrap, first, though. You'd be insulating the heat energy within the housing, thus making the operation of the turbine more efficient, while simultaniously lowering underhood temps.

Just my 2 cents. Bottom line is this:

Get what you want and can afford. Then, toss out everything everyone else tells you when you reach the point where you smile while you drive.

[hysteria]

dont know if it was said before but bottom mount have less clearance issues. my top mount is very close to the brake lines.

[sil80drifter]

i may be postwhoring but...yes it has been said before.

sil80