Top mount max BHP
 

Hi guys, not overly keen on going front mount, so was wondering what sort of numbers people are running with top mounts.

Mine is an 04 wrx and i was thinking of upgrading to an sti top mount or possibly a proven aftermarket top mount.

Just want to know what gains i could expect over the standard wrx item, obviously this is turbo dependant, i would be running my vf34 if i decided to take this route.

Also any recommendations as to which aftermarket top mount is a worthwhile upgrade.

400 is a figure mentioned a lot so around there will be fine.

+1, but even the standard WRX top mount will be good to 330-340bhp. I'm running a WRX top mount on my classic with a VF28 at 330bhp.

I would say about 350bhp, anything good quality FMIC would be safer. If you are to get one, make sure you get one with a nice efficient core - there are cheap options out there, but would perhaps be less efficient than your standard TMIC.

Give this a read - one of the most highly respected Scooby tuners around, Bob Rawle:

http://www.brdevelopments.com/solutions.html

350 :lol:

Ask Andy Forrest how he manages to get approx 450 out of his TMIC

I ran around 420 on a STi topmount before swapping to a FMIC with no problems

Bez is running 480odd on a hyperflow top mount. If your using a vf34 in will not trouble a newage sti topmount.

on a vf34 then new age sti will do ok, but keep in mind your still running a top mount, so on hot days dont boot is as soon as you come out of traffic.

Just out of curiosity why so dead against a front mount?

STi top mount is OK,but still FMIC is way to go,i will never look back to top mount.

Mainly depends how much bhp you are want at future,if its just VF34,you should be OK with STi top mount,but i know few guys which run VF34 on top mount and he makes under 340bhp,later he swap for FMIC and afterwards remap and he made 350bhp without the meth...



Jura

I think a few people don't want to chop their front bumper up and spend several hundred pounds on a front mount to get 10bhp when an sti top mount is perfectly adequate. Yes, a front mount will give better results but when on a budget and not trying to push for that extra few horses a lot of people are happy with the performance of a TM.

The main reasons are the cost, wrx internals, cutting the front bumper and the v34 won't make much over 350, which is the limit on the engine and gearbox, i also prefer zero lag and drivability over out and out power, somewhere around 330 bhp is fine for now.

I also want to just run the car for a while collect parts at the right money before considering the next step which would be 450/500 but as we all know that costs, and i don't see the point of going front mount until then for the sake of 15/20bhp at the risk of my engine and box.

With some FMIC you don't need chop bumper,no several hundred pounds for good FMIC as Japspeed or Harvey HDi GT,cost lot less than APS,Perrin,Hyperflow TMIC or FMIC and will be at end cheaper than STi TMIC

Not just extra bhp,but extra safety in you are looking tracking your car..


Jura

As i said you don't need with some FMIC chop bumper,yes with some no name yes you must.
I've run FMIC on mine WRX like with TD04 and later with VF34,if its car mapped properly you will see low increase of lag.


Jura

I don't have any plans to go on track with this car, if i ever do that again i would just buy a £500 sh1ter and drive it like i stole it until it broke, then buy another, i think it's much cheaper and just as much fun, as i have no racing asperations.

Not even sure i will go for 400/500 bhp yet, too many factors for me to be looking that far into the future, the only things that are set in stone at the moment is that i will start to build another engine for this and learn how to build gearboxes:D

Another side note, how does the TD04 compare to the VF34.

td04 does spool initialy quicker from dead start, but once going through the gears i didn't notice any major difference apart from not as much drop in peformance up the rev range. By far a worthy upgrade, although sc36 is worth lookign at too.

I've run both turbos on FMIC and difference between these two has been mind blowing.Mainly in power and torque,nice sound of roller bearing turbo :D probably best turbo for WRX without the doubts.Yes spool is little bit later than TD04(around 200-300rpm),but driving with VF34 has been much better in any gear.

I've tried VF35,but i don't know i've been disappointed with this turbo,this has been on STi.

Jura

sti top mount is fine, cosworth hatch has 400bhp with an sti tmic!

Yep thought the vf34 would be better, you should try one in a classic, they pull so hard i'm sure it could snap someones neck, fantastic for coming out of corners, lol at the sound, people think there is something wrong with it when they first hear the whine :D

Ive bought one of harvys front mounts and it does need the bumper cutting. And the car can be mapped perfectly safely on a top mount. When aiming for the low to mid 300s the main benefit of a front mount is being able to get the maximum power from the turbo. As the OP has said this isn't his intention nor is any track work on the cards. So a top mount, especially at the low prices theyre now fetching would be perfectly adequate. For the extra cash and effort fitting, the 10hp gain really wouldn't benefit this guy.

If you are going to fit an STi top mount in place of your WRX you must fit the undertray or you are wasting your time. The bigger air scoop also helps.

Was planning on fitting the scoop if i can find a genuine one, and i know about the under tray for a classic but is it still required for the blob?

Yes you need the sti undertray, scoop would be good as well

Yes. Required as Tez says.
It may help your understanding if you read the project thread by Shaun and pay particular attention to his dilema TMIC v FMIC and his findings.
Generally, ver 1 and 2 cars will benefit from an efficient FMIC by 280 bhp. STi 3-6 will benefit somewhere between 300 and 320 bhp subject to turbo in use and New Age WRX, certainly by 350 bhp and Stis another 20 bhp on top of that.

Thanks harvey i'll be in touch in the not too distant future :)

To try to explain further this is not really a meaningful question.
If you get a big enough turbo I guess you could make a ver 1 or 2 WRX produce 500 bhp with a slanted top mount. Goodness knows what the air charge temperatures would be, possibly in excess of 100C. or how long the car would be capable of doing that. Now if you put an efficient front mount on with the same turbo chances are you would be closer to 600 bhp.
There is no exact answer to the above question. You can force enough air through a top mount to produce power inefficiently with a lot of heat. Surely the objective is to find the point at which the top mount becomes inefficient and a change to an efficient front mount becomes worthwhile. This will not be the same point on every car because different turbos have different efficiency operating windows. For instance a 16G to an STi 6, it will operate efficiently to produce around 320 bhp but if you up the boost and attempt to produce 350 bhp your ACTs will have rocketed because the turbo is no longer efficient. Now if you fitted a 20G to the same car you would find your air charge temperatures at 320 bhp would be far lower and even at 350 bhp on a proper 20G temperatures would probably still be manageable. While you could live with the 20G at 320 bhp on the STi 6 you would find that fitting a front mount at 350 bhp you would pick up a lot of power because of the more efficient core and reduced ACTs and you would still pick up power on reduced wastegate duty cycle which would further reduce ACTs.
So I hope people come away from the idea that there is a set power you can produce on a top mount. You will see that the sceptics were predicting that Shaun was taking a step backwards fitting a front mount but that was because there was a lack of knowledge on their part and the proof was in the pudding.
Now finally, this myth about front mount intercoolers causing lag. I am sure some do but there is some right crap out there despite the glossy advertising. Providing the core is efficient and tube and fin is the most efficient in terms of flow and providing the pipework is properly designed with radius bends and providing the car has been properly mapped, there will be no noticable lag and the benefits from increased power and torque (providing the car at an appropriate power level) far outweigh any possibly minor detractment.

I know it's an old thread but I've just bought a mitshimoto top mount for my 08 wrx. Question is, shall I stick with the standard wrx scoop undertray or replace it with an sti one ?. Obviously the sti try is longer whereas the wrx tray is a box shape to match the intercooler.

If the new TMIC is bigger than the WRX one, I would have thought the answer was obvious?

It's a bigger topmount but is the same shape as the standard wrx one. With the sti tray being longer I didn't know if it was worth changing it over to an sti one.

So you've bought one of these??

http://ep.yimg.com/ay/yhst-131888433...ash-2014-2.jpg

http://www.mishimoto.co.uk/subaru-wr...er-08-14.html#

In the write up it says

"Fits with stock hood-scoop shroud"


From your previous posts you seem to be confusing Newage gear with Hatch items - they are different.