legacycentral bbs

Ok, here is what my understanding of the situation is and anyone that has done testing and knows what the effects of the two possible locations are I welcome them to weigh in on this discussion. I am considering turbo-ing my old wagon. and I believe the reason the factory uses the top mount is to minimize turbo lag. It makes sense that the intercooler effectiveness is compromised by being located there. That said, for better cooling the intercooler should be out front but now that introduces significant turbo lag. Please, someone who really knows, weigh in on this and set the record straight.

What turbo do you want to use? Also where are you located? I live in Washington and with our moderate weather i havent had a problem with the top mount and a td05 with a decent turbo blanket. Thats with nothing directing air flow from the scoop to the tmic either. If i lived in Arizona or Texas it would be a different story.

For the best of both worlds you could use an old legacy air to water intercooler with either a stock or aftermarket heat exchanger on the front of the car. Minimized lag and direct cooling.

On my front mounted legacy with a td04 the lag is hardly noticeable, it also has a slightly better top end power feel over the top mounted intercooler.
On my impreza I chose to use a top mount over front because I rally that car and didn't want to risk rocks/debre causing damage. Also in the event of a possible front end accident with the use of a top mount I may have a chance of still being able to drive the car versus a front mount getting damaged.
As for efficiency, Subaru has deemed their top mount suitable for turbos like the td04, vf39, exc. But anything much bigger it's recommended to use a front mount.

I went fry mnt with my td05, there's is a lag, but not terrible

thanks guys, I appreciate the input. I have decided to stay normally aspirated at least for the foreseeable future due to economic considerations and preferring to have a car I dont have to fiddle with too much to keep running. From what I have seen here and in other places, turbos add a whole new level of complexity and a real strong possibility of troubles that are hard to sort out. More trouble than it is worth I believe at this point. On the other hand, a total factory engineered system has so far been pretty sweet on my WRX. I think I will keep the wagon NA.

dankberries wrote:On my front mounted legacy with a td04 the lag is hardly noticeable, it also has a slightly better top end power feel over the top mounted intercooler.
On my impreza I chose to use a top mount over front because I rally that car and didn't want to risk rocks/debre causing damage. Also in the event of a possible front end accident with the use of a top mount I may have a chance of still being able to drive the car versus a front mount getting damaged.
As for efficiency, Subaru has deemed their top mount suitable for turbos like the td04, vf39, exc. But anything much bigger it's recommended to use a front mount.

So its as much about turbo size as it is about the other factors I mentioned in the original post. I am very much a turbo newby in terms of knowing about some of the aftermarket products and the appropriate application of them. That is really interesting. So based on what you have said, the top mount IC on my 2009 WRX is probably borderline in terms of efficiency and effectiveness and its a coin toss whether to leave well enough alone or go front mount. It is totally street driven or occasionally autocrossed. I think from the standpoint of collision protection the top mount is sensible on a street driver. IF I was drifting the car or some such thing I might be tempted to go the other way.