QG18 & QG15

cdx2k1 · Postby **cdx2k1** » June 9th, 2006, 10:04 am

Hi all.Is the box/auto tranny that's used on the QG18 the same as the QG15?Also, is the throttle body the same?What about the exhaust manifold/exhaust ports?

Postby **Dave** » June 9th, 2006, 10:08 am

transmissions - they are interchangable but the ratios are slightly different
throttle body - same
exhaust manifold/exhuast ports - same

JWT · Postby **JWT** » June 9th, 2006, 10:48 pm

wil bolt

Picasso · Postby **Picasso** » June 9th, 2006, 10:52 pm

^^Were you really smiling like that when you typed it?

k.c.151 · Postby **k.c.151** » June 12th, 2006, 8:41 pm

my mechanic told me it will line up bolt 4 bolt... i thinkin bout ah little frankinstein in that regard...

JWT · Postby **JWT** » June 12th, 2006, 11:18 pm

it will bolt and it will raise hs compresion but that project not worth while

ever hear the sayin no replacement for displacement
:mrgreen:

k.c.151 · Postby **k.c.151** » June 13th, 2006, 4:59 pm

yeah...jus lookin at alternatives instead of goin sr20... :mrgreen:

cdx2k1 · Postby **cdx2k1** » June 13th, 2006, 7:06 pm

Im going to polish the throttle body and port the head>maybe polish it too

JWT · Postby **JWT** » June 13th, 2006, 10:08 pm

the QG18 needs alot of head work to extract the power from that engine

cdx2k1 · Postby **cdx2k1** » June 13th, 2006, 10:50 pm

^^gimme some tips.Non turbo tips that is.

Postby **Dave** » June 14th, 2006, 8:02 am

just restrict your work to polishing and not opening(porting)
u stand a great chance of the head cracking between ports is u bore out and don't go more than 220grit on the intake

cdx2k1 · Postby **cdx2k1** » June 14th, 2006, 11:19 am

^^What's 220grit on the intake? :oops:

Postby **Dave** » June 14th, 2006, 11:38 am

thats the spec on the polishing bit, meaning when polishing use a 220 grade polishing bit on the tool

acesinghit · Postby **acesinghit** » June 14th, 2006, 4:37 pm

ent all the QG and QR have the same tranny? has anyone ever replaced a QG15 and a 16 with a QG18DE? Hell I wanna drop a QR25DE in a ALmera and put a 5FWD in it........Dave dude, what advice u have?

redsupra101 · Postby **redsupra101** » June 14th, 2006, 10:55 pm

^ if u going qr25de, why not do it properly and go with the 6fwd box instead? :mrgreen:

the tranny's arent the same
they bolt up yes but the ratios are different
ie if u take a qg15 engine and put a qg18 tranny
if the gears usually changed (at 6500rpm) at 40km/h 1-2 and 80km/h 2-3.... they gonna end up changing around 60 1-2 and 100 2-3
ur fuel economy should improve as your cruise rpm will drop by about 500~1000 but your accel and low end power should decrease

cdx2k1 · Postby **cdx2k1** » June 15th, 2006, 10:48 am

Dave,where can I get the polishing bit?Searched hi and lo but can't find it

cdx2k1 · Postby **cdx2k1** » June 16th, 2006, 8:20 am

Since the QG15 is a lean burn engine, can I put some more fuel (to get to stoich) to get some extra hp?

Picasso · Postby **Picasso** » June 16th, 2006, 9:21 am

cdx2k1 wrote:Dave,where can I get the polishing bit?Searched hi and lo but can't find it

Waste of time

Since the QG15 is a lean burn engine, can I put some more fuel (to get to stoich) to get some extra hp?

When it is said that it is a " lean burn engine" it means that engine doesn't consume alot of gass and the paremeters that the ecu is alowed to dump fuel is very much conservative. CDX all you need is a Apexi controller to increase fuel where the ecu tends to cut back and also somthing to retard and advance the eninge timming. But you don't need to go so far yet cause you haven't run a free flow exaust system yet nor have you even tampered with the pulleys and spark plugs. If I were you I will do these things first and see how the engine performs b4 I go tampering with the head of the engine. Take things in tiny steps and don't jump all out and start playing with fire. That engine is a funny lil mofo. You may think that you are getting added power when truely you are just making alot of noise. Don't pray for any aftermarket company to hack the ECU codes cause 1) it sure is hard as hell to crack and 2) The aftermarket companies have noticed long time that this is the black sheep of nissan ( meaning that the engine is not very responsive to mods.) I have given up on it cause the amount of money you are going to spend to make the power out of the eninge you will do better with a GA16DE slightly ported out with a free flow exause,intake,gearbox,upgraded ignition sytem and some cams

I know you all with agree with me.

cdx2k1 · Postby **cdx2k1** » June 16th, 2006, 11:49 am

What can advance/retard the timing?

Picasso · Postby **Picasso** » June 16th, 2006, 11:59 am

^^ MSD has a unit that does it.. I think it is the BTM.. ( correct me if I am wrong )

Boss if you want to stick with your QG first upgrade and I will sugest to anyone get a dam gear box first. You have no idea how much power that tranny robbing you power.

cdx2k1 · Postby **cdx2k1** » June 17th, 2006, 5:11 pm

I just read that the QG18DE is a direct injection engine>continuously variable timing...will read up if this applies to the 15..

Snags · Postby **Snags** » June 17th, 2006, 5:42 pm

Doesn't burn engine my ass

...car sucks gas like hell man

belalegosi · Postby **belalegosi** » June 17th, 2006, 8:10 pm

start sneezing yooo :mrgreen:

lol

k.c.151 · Postby **k.c.151** » June 18th, 2006, 2:41 pm

i agree with casso... get a gearbox first and do things step by step...

JWT · Postby **JWT** » June 18th, 2006, 9:53 pm

qg18de with a gearboc you orn like socks that does pull very well and you will enjoy it especially from 1st to 2nd from 3rd sr20 will eat you

displacement :mrgreen:

Strugglerzinc · Postby **Strugglerzinc** » June 19th, 2006, 9:27 am

cdx2k1 wrote:I just read that the QG18DE is a direct injection engine>continuously variable timing...will read up if this applies to the 15..

The QG18DE is not direct injection it is Multi Port. The QG18DD is the direct injection version.

http://en.wikipedia.org/wiki/Nissan_QG_engine
http://www.freshalloy.com/site/features/tech/engines/home_codes.shtml

cdx2k1 · Postby **cdx2k1** » June 19th, 2006, 10:33 am

^^Strugglerzinc, http://www.nissanforums.com/qg18-1-8l-e ... g18de.html If you find anything proving me wrong please do so beacause this is a learning experience about the QG :!:

Strugglerzinc · Postby **Strugglerzinc** » June 19th, 2006, 12:13 pm

i can take a pic of a QG18DE engine and intake manifold with the injectors mounted on it that i have at home (if i had a camera). as shown on the freshalloy link, when reading the engine code DE means DOHC multiport fuel injection. the QG15DE in our B15 is also MPI, same or similar to the QG18DE.

cdx2k1 · Postby **cdx2k1** » June 19th, 2006, 2:14 pm

^^Understood.

Picasso · Postby **Picasso** » June 19th, 2006, 3:18 pm

The QG18DE is not direct injection it is Multi Port. The QG18DD is the direct injection version.

That is true. Their are two versions of this engine. One that has an aluminum valve cover and the other is plastic. The one with the aluminum valve cover has a solenoid directly on top for the VTC. In addition the manifold is different and it is a direct injection setup. The manifold resembles the SR20DE low port. The other version has the plasic head like the QG13,15 and 16.. This one has VTC also but the solenoid is on the side. cdx2k1 you are making this thing sound very hard and very techical. Boosting this engine is simple like anyother and there is no set of maths involved to do it. The guy who boosted the QG18DE on the forum Chimike ( I eh know if I spelt his name wrong ) Pmed me that the QG15D and the QG18DE are basiclally the same it's just the newer QG15DE's have VTC and the older ones don't ( which is what you have ) It is a straight fwd setup pluss he has in detail made it public knowledge how to boost the engine. You are simply confusing your self by looking at all the info and asking too many unecessary questions. Is either you doing it the right way which is how it is in detail on the guy's website or you do it the cheap way which is bolt on a turbo and drive with the ECU fuel mapping a.k.a KABOOM!! But let me ask you a question right? do you have the money to do it in the first place cause asking all these questions with no fincial funding = waist of time.

Save your internet hours brother is that is the case.

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