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Discussion Starter · #1 ·
I have read in several magazines, websites, etc... that the 2.5 engine is not a good engine one is thinking of modifying it. I don't know about the 3.5 engines but I don't recall reading anything negative (yet) about that v6 engine. I have read that increase in pressure in the 2.5 engine can cause blown blocks and headers...that is.. even a small amount of pressure. Also the redline sucks due to bad valve spring. Did V6 owners hear anything negative about the v6 engine?
 

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I have a NISMO oil cap
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And can you list all these magazines, websites... etc? I'd like to see for myself how supposedly shitty my engine is, when I myself have yet to see anything like what you've mentioned.
 

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Discussion Starter · #3 ·
ThaiBruin said:
And can you list all these magazines, websites... etc? I'd like to see for myself how supposedly shitty my engine is, when I myself have yet to see anything like what you've mentioned.
I am not trying to diss this car. I too have a 2.5 engine and was dissapointed with all the stuff they wrote about this engine.
I know one of the article (very nice one) was done by Sports Compact cars.
http://www.sportcompactcarweb.com/archives/tech/tech02_0401.shtml
that's where the article is.
Also, look through some other sites. You'll find a lot of negative remarks about this engine.
 

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I have a NISMO oil cap
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hmmm...

Well, at least the last two paragraphs of the article you listed has some encouraging words:

"Weaknesses like the thin ring lands and open block deck are only important at extremely high specific outputs. The point that is easily lost about the QR25 is that it is HUGE. Two and a half liters is a lot of displacement, and you don't have to lean on it very hard to get big power. Stock output is 180 hp at 5800 rpm, and word from inside Nissan is there is at least 10, and possibly as much as 20 hp bound up in a restrictive exhaust system.

Beyond simple intake and exhaust mods, a light-pressure turbocharger or supercharger seems to be the obvious route for horsepower. Camshafts will be expensive because of the requirement for valve springs and different buckets to maintain proper lash adjustment. Five psi of boost on top of 2.5 liters, however, should make a lot more power and shouldn't cost any more than they would on any other engine. What do you know; maybe the V8 boys had a point about displacement."
 

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If a ford focus with, the same cat setup, way shittier pistons, a standard ignition, nearly a liter less displacement, and an absolutely terriblely constructed bottom end can be tuned than the sky is the limit with the 2.5. You could probably get quite a bit more horse power out of the 2.5 with just a crank pulley, new valve springs, and a reconfigured exhauste. Not to mention the fact (even though it has nothing to do with the engine) that you can get a factory LSD and six speed ( wich has some short gearing) attached to that motor for under 18000 in a car we all know.
 

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Discussion Starter · #6 ·
Well.. i was just trying to say that this engine is not a good 'soupable' engine.
 

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Discussion Starter · #8 ·
Did anyone find ANY negative feedback regarding the 3.5 engine?
 

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why wouldn't you trust what scc writes, especially about nissans?
I've been reading scc for years and I think they can be little advertisement driven at times, but what media publication isn't.
They (Sport Compact Car) are pretty much the only import car mag that actually does there homework on a reliable basis. They dyno everything and most of the time tell there truthfull opinion, granted it's an opinion but I think that in general they write abouth the more interesting things involved with being a car nut instead of just about rims and paint.
 

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Discussion Starter · #11 ·
justinm said:
why wouldn't you trust what scc writes, especially about nissans?
I've been reading scc for years and I think they can be little advertisement driven at times, but what media publication isn't.
They (Sport Compact Car) are pretty much the only import car mag that actually does there homework on a reliable basis. They dyno everything and most of the time tell there truthfull opinion, granted it's an opinion but I think that in general they write abouth the more interesting things involved with being a car nut instead of just about rims and paint.
I AGREE
If u go to the website i posted, you can tell that they did their homework. They basically tore down a new engine to write that article.
 

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They're really concentrating on some of the more extreme types of tuning. Nissan engines are damn near bullet-proof and I'm confident the QR25 could handle every standard bolt-on mod without a hiccup. It's when you get into forced induction and NOS where the ring lands and thin block castings will become issues. In fact, the QR25 will probably respond really well to a header because the goofy mini-cat that sits right outside of the exhaust ports really chokes off the flow. As an engine to modify, it's probably above average. It's just not going to stand up to huge boost levels like an SR20 or VG30.
 

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I say only time will tell if the QR is a good tunable engine. No one (except for that Spec-V that had a Borg Warner supercharger installed by Area 51 Fabrications) has ever attempted any sort of tuning to that engine because it is new - so just let those pros do the tuning and reporting.

Don't try to speculate. If you see someone with a supercharger bolted on the QR25DE (a la SC Spec-V) and it runs well - then we all know it is possible.

I for one would like to hold on to my hopes.

Joe :)
 

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lol dont listen to sports compact cars
they for some reason hate nissan's
for some reason a 175hp engine that puts 140hp to the wheels is bad (ser v-spec)
but a 200hp engine that puts 155hp at the wheels is good (rsx type s)

the 2.5 is a great engine and has already proved to stand up to a supercharger and n2o
so its a great engine just give it time
 

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Discussion Starter · #15 · (Edited)
nismoalty said:
lol dont listen to sports compact cars
they for some reason hate nissan's
for some reason a 175hp engine that puts 140hp to the wheels is bad (ser v-spec)
but a 200hp engine that puts 155hp at the wheels is good (rsx type s)

the 2.5 is a great engine and has already proved to stand up to a supercharger and n2o
so its a great engine just give it time
Well I read some posts and saw someone with a blown engine. And I visited some sites with people having problem with blown/cracked block. The engine is good for a sotck engine and I bet it can handle more HP... but I doubt that it can withstand much more pressure.
And one more question.. so the QR25DE is a totally new, innovative engine and the VQ35de was there for some period of time? This is my first Nissan so I don't know much about their engines.
 

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NEO1995 said:


And one more question.. so the QR25DE is a totally new, innovative engine and the VQ35de was there for some period of time? This is my first Nissan so I don't know much about their engines.
Yes, the VQ series engine has been around a while in the Maxima, since 96' I believe. Except they bumped up the displacement from 3.0 to 3.5 and added CVT technology for 02'.
 

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scc just rated the spec v the number 2 best of 8 great rides for 2002. being beat by the WRX.Let's face it. i'd buy a wrx if I could afford it over a spec v. So, i don't know why you think they dislike nissan.

And the second issue, blown engines. Do you mean that you have read posts and articles and know or saw blown spec-v motors?

Operator error is my favorite saying!
 

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NEO1995 said:
Well.. i was just trying to say that this engine is not a good 'soupable' engine.
why the hell would you want to mod a 2.5 engine. That is why they make the v6. Normally people like my self buy the 4 cyl. becuse of increased gas mileage.
 

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just read the comments that they make about nissan shit
u dont here them talkin about the millions of b-series engine that have blown
up
just because they did crack doesnt make it a bad engine
for mods u dont know how the person treated it with what amount of modding
and it couldnt have been done right since its a brand spankin new engine so
people dont know the do's and dont's of this engine
just like any car some engine have been known to blow on a 50 shot and others have known to run a 100 shot with no problems

as i said i also know of a 2.5 that has run a supercharger and nos for a while with no problems its all how u treat the engine

and no the 3.5 isnt a totally new engine
it was seen in the past year or two in the pathfinder
just givin small changes like the valve timing and shit
 
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