topmount or stock location? - GT-R Register - Official Nissan Skyline and GTR Owners Club forum

kismetcapitan · 2nd September 2006, 03:40 AM

You see topmount turbos when people are running huge turbos that won't fit in the stock locations, but I'm thinking that topside mounting may make sense even for smaller turbos, as it just seems the turbos will cool better in that position, especially if a vent is placed above them in the hood. It'd also keep heat rising off the turbos from heating up the tube feeding the turbo side of the FMIC (dunno what it's called, it's the piece that says "twin turbo" on stocker setups).

It may not look impressive with 2530-ish sized turbos placed front and center, but maybe they'll live longer. Thoughts?

TokyoJoe · 3rd September 2006, 09:17 AM

I had an old Pontiac with a roots blown 3.8litre and I changed the hood to a dual scoop hood, mostly for looks but figured it might help temps....not a chance.

Turbo's and outlet temps are hot no matter which way they are mounted. I think the gains would be minimal at best if you would even be able to see any and you would be better off upgrading to a more efficient IC if temp is an issue.

ahapartridge · 3rd September 2006, 09:03 PM

The downpipes have a better flow angle when using low mount, with top mount you are going to need two near 90 degree bends

Warpspeed · 4th September 2006, 12:26 AM

Top mount can cause some massively high localised bonnet temperatures which may in time cause problems with the pintwork. Any air openings in the bonnet will also allow rainwater to flood over your engine causing ugly rust. I have tried some of these ideas over the years myself, and have discovered some of the problems the hard way.

If you are building a show pony, fair enough. but if you want a practical reliable everyday road car stay low mount.

2nd September 2006, 03:40 AM	#1 (permalink)
kismetcapitan GTR Register Member Join Date: Nov 2005 Location: Seoul Korea Posts: 6,593	topmount or stock location? You see topmount turbos when people are running huge turbos that won't fit in the stock locations, but I'm thinking that topside mounting may make sense even for smaller turbos, as it just seems the turbos will cool better in that position, especially if a vent is placed above them in the hood. It'd also keep heat rising off the turbos from heating up the tube feeding the turbo side of the FMIC (dunno what it's called, it's the piece that says "twin turbo" on stocker setups). It may not look impressive with 2530-ish sized turbos placed front and center, but maybe they'll live longer. Thoughts?

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3rd September 2006, 09:17 AM	#2 (permalink)
TokyoJoe GTR Register Member Join Date: Aug 2006 Location: YOKO-YOKO Posts: 130	I had an old Pontiac with a roots blown 3.8litre and I changed the hood to a dual scoop hood, mostly for looks but figured it might help temps....not a chance. Turbo's and outlet temps are hot no matter which way they are mounted. I think the gains would be minimal at best if you would even be able to see any and you would be better off upgrading to a more efficient IC if temp is an issue.

3rd September 2006, 09:03 PM	#3 (permalink)
ahapartridge GTROC Member Join Date: May 2003 Location: Warrington Posts: 1,125	The downpipes have a better flow angle when using low mount, with top mount you are going to need two near 90 degree bends

4th September 2006, 12:26 AM	#4 (permalink)
Warpspeed GTR Register Member Join Date: Apr 2003 Location: Melbourne Australia Posts: 169	Top mount can cause some massively high localised bonnet temperatures which may in time cause problems with the pintwork. Any air openings in the bonnet will also allow rainwater to flood over your engine causing ugly rust. I have tried some of these ideas over the years myself, and have discovered some of the problems the hard way. If you are building a show pony, fair enough. but if you want a practical reliable everyday road car stay low mount.