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Discussion Starter #1
What is done to the specV engine to change the compression ratio from 9.6 to 10.5? Crank shaft? Pistons? Heads? New block(doubt it). I have a feeling they are taller pistons. Anyone have an idea where these can be had?
 

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Discussion Starter #5
Engine
QR25DE – 2.5-liter DOHC 16-valve 4-cylinder engine
177 hp @ 6,000 rpm
172 lb-ft of torque @ 2,800 rpm
Compression ratio – 9.6:1
QR25DE – 2.5-liter DOHC 16-valve 4-cylinder engine
200 hp @ 6,600 rpm
180 lb-ft of torque @ 5,200 rpm
Compression ratio – 10.5:1
2008 Nissan Sentra SE-R Specifications - Nissan USA

If you find a better source let me know. :p
 

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I looked in the FSM and cant see any difference in head height, pistons or block deck height. maybe its just the head gasket ? Can some one check the part numbers ?
From the FSM
 

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Discussion Starter #7
It's weird. A head gasket can't up the compression that much could it? I thought it was a revised cylinder head. I would ask the people at my dealer, but like most dealers, we know more about their cars.
 

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First off are your talking about the b15 platform or the b16 platform sentra? Those specs you gave are for the 07+ ser and spec-v.
2006 Nissan Sentra SE-R - Top Speed
the 02-06 ser and spec-v difference is from tuning like stated.
the 07+ ser and spec-v are a complete different story and the difference comes from the comp ratio, a resin intake manifold , revised cam profile and one of the bigger differences is the raised redline from the new crankshaft.
2007-2008 Nissan Sentra SE-R Spec V Review - Modern Racer - Auto Archive
 

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Its in the link above
revised piston crown shape to support a higher compression ratio (10.5:1)
So change the pistons to get 10.5 : 1
 

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Thanks for finding that info ianhen. I figured there had to be some truth to the difference between the two engines and not just "misinformation".
 

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Thanks, I was also wondering the same thing.

So what are some cheap/easy things to do to bump it up to 200+? I'm very new to these cars, so all I know about are intake, exhaust, and things like that. Any other good ones?
 

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Discussion Starter #13
Not without spending a lot of money.. or with lots of labor. A heard of some people using the sentra pistons in the 2.5 engines which bumps up the compression. It might bump it up to as high as 11:1. I just remember he had to run something along the lines of 93 octane. There are aftermarket cams which do about nothing. The real gains are from forced induction or upping the compression.. both of which will require lots of labor.
 

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Not without spending a lot of money.. or with lots of labor. A heard of some people using the sentra pistons in the 2.5 engines which bumps up the compression. It might bump it up to as high as 11:1. I just remember he had to run something along the lines of 93 octane. There are aftermarket cams which do about nothing. The real gains are from forced induction or upping the compression.. both of which will require lots of labor.
no, the compression is different, k thanks
What’s the best piston ratio I’m looking for 12 or 14 any website
 

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2007 Nissan Sentra SE-R
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So if I have a 2007 SE-R what can be done to make it similar to a spec v if it’s just an ecu
 

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09 Altima 3.5SE 6MT Sedan
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Transmission with the LSD would be my #1 stop.
 
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