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On it like a GTR bonnet
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396 Posts
Discussion Starter #1
Hi guys, i bought my 1st skyline on monday =D R32 gts-t type-m, its a fantastic car, but the engine is so far untouched. I have searched around and cant seem to find alot of info on tuning the RB20DET aside from a couple of basic guides. I was wondering what mods you guys uave done and what bhp figures you have achieved? Or if anyone has a good knowledge of tuning the rb20 then please share your views =) im looking to keep the stock ecu and have it remapped once i have fitted a bigger turbo, injectors, afm etc, thats all i know so far
 

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Everybody knows that the bird is the word
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9,198 Posts
The 20DET ECU can handle a lot more abuse than the 25DET ECU... by that I mean you can modify your car quite a lot and the factory ECU will happily run it, sure it won't be running at optimum power but it means you can do some mods (over time if it suits), save up for the bits that do need a new ECU OR chipped ECU to run (injectors, large turbo etc), then at the last minute fit the injectors etc, tune it and you're done.

How far you take it depends on your budget and goals for the car...

Like any car, do the basics first... full turbo back exhaust (3" is ideal), high flow air filter - if it's a POD do a cold air box/intake. The factory 20DET air box is constipated so a POD is probably a better idea.
A FMIC would be next.... and if you wanna get fancy, do a front facing plenum at the same time

I'll give you a list of things I've done to my car and a few details below to give you some idea....

K&N POD
Cold air box
Cold air intake
FMIC
RIPS front facing plenum
80mm throttle body
HKS Hi Power cat-back exhaust (brand/quality matters... I bought the car with an aftermarket exhaust - I didn't like it so fitted the HKS and gained power)
RB25DET turbo (running the 20DET actuator)
Light weight flywheel
Up rated clutch

There are more mods, but they aren't really related to power increases... (catch can, suspension, BOV, R34 mags, alloy radiator etc)
My a/f ratios are all safe too, even with all of those mods (shows how flexible the stock ECU is)

I was talking to a guy not long ago who recently had his 20DET chipped and tuned... his car is less modified than mine. Before the chip/tune his car made around 145rwkw, after his car made 199rwkw. That's roughly a 25% gain in power JUST from a chip and tune :eek:
I suspect my car should easily break the 200rwkw mark when I finish off a few bits (front half of the exhaust, fuel pump etc) and get a chip and tune.

I can't really give you a basic guide to modify from cos beyond a pod, exhaust, fmic things are no longer 'basic' and variables increase.


I've done most of the work myself and this is what the car now looks like. I bought it in a very similar state to yours - except mine was sitting on ugly standard R33 wheels, no name pod and exhaust



 

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Interesting do you think I could get away with putting a gt28rs on a similar set up to yours but with ebc but no fancy plenuim! 3" elbow back with decat all proper branded stuff rsr downpipe, japspeed decat, apexi cat back all 3" and big fmic and an apexi super intake filter.on the standard ecu? It would hopefully only be for a bit until I either stick the 25 in or get mine tuned.
Thanks
 

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On it like a GTR bonnet
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396 Posts
Discussion Starter #4
thanks for that banter's minion, so far mines got an apexi filter, 3" downpipe and 3" cat back system. my plan was, 3" the rest of the exhaust.. mahoosive fmic, walbro 255.. then wind the boost up to 12psi which i gather is all the stock turbo can take. Then over the winter sort the body work etc and shop for some yellow jackets, whatever large turbo i come accross cheaply, 444cc injectors... cant remember if theres anything else im forgeting but basically im looking for around 350 bhp
 

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Everybody knows that the bird is the word
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9,198 Posts
Interesting do you think I could get away with putting a gt28rs on a similar set up to yours but with ebc but no fancy plenuim! 3" elbow back with decat all proper branded stuff rsr downpipe, japspeed decat, apexi cat back all 3" and big fmic and an apexi super intake filter.on the standard ecu? It would hopefully only be for a bit until I either stick the 25 in or get mine tuned.
Thanks
Standard ECU won't run it... well, it will but if you hit boost you're running the risk of doing serious and permanent damage to the engine... and it can happen very fast. It's recommended you don't drive a car once a larger turbo is fitted till you get it tuned, or if you do it's short distance only (to the tuner) and do not hit boost. The physical size of the gt28rs looks similar to the stock turbo but don't let that fool ya... it's not about physical size, its about flow and the gt28rs can flow waaay more than the stock turbo.
Ya can get away with fitting the 25DET turbo on a 20DET and hit boost without a tune because they don't flow a hell of a lot more than standard... and to be extra safe, I'm running 2psi less boost than I did with the standard turbo (that's what the engine naturally wants to boost with that turbo - I don't have any form of boost control)

I did have a quick look at a few gt28rs turbos thanks to google (mainly so I know what your talking about lol)... I keep noticing one interesting spec 'Flange - T25'. Do they come out T3 too?
T25 is the flange the SR engine uses and won't bolt straight up to an RB


thanks for that banter's minion, so far mines got an apexi filter, 3" downpipe and 3" cat back system. my plan was, 3" the rest of the exhaust.. mahoosive fmic, walbro 255.. then wind the boost up to 12psi which i gather is all the stock turbo can take. Then over the winter sort the body work etc and shop for some yellow jackets, whatever large turbo i come accross cheaply, 444cc injectors... cant remember if theres anything else im forgeting but basically im looking for around 350 bhp
How big do you call 'mahoosive' lol?
Most fmic kits (for R32, R33, R34, C33, A31 etc) are all the same (yep, same piping n all) and they usually come with a 'standard' size cooler - 600x300x76. This size will support a lot of power. Alternatively, you can fit a GTR fmic and get a piping kit to suit (different end tanks to a typical 'off the shelf' cooler), the GTR cooler is good for 600bhp.

I've always heard the rule of thumb is
20DET turbo - 14psi max
25DET turbo - 12psi max
Some will run for years on higher boost, some will crap out on less boost... but that is a rough guide of what's considered safe.



This is the fmic on my car - it's a 600x270x76
I have plenty more pics of exactly how I've fitted it if you think ya may need them ..?

 

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On it like a GTR bonnet
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396 Posts
Discussion Starter #6
mate, your a legend, i could do with all the pics youve got on how you mounted that beast! nice one, the fmic kit im going for is 600x300x76 (i just thought it was mahoosive compared to the one on my old sx lol) so 14psi on the stock rb20det turbo? once i have a bigger turbo etc and all mapped up, what psi can i take the engine up to before it starts to lift the head etc?
 

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On it like a GTR bonnet
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396 Posts
Discussion Starter #7
mines exactly the same colour btw, its good to see how itll look with a huge intercooler in the nose =)
 

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Everybody knows that the bird is the word
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9,198 Posts
mate, your a legend, i could do with all the pics youve got on how you mounted that beast! nice one, the fmic kit im going for is 600x300x76 (i just thought it was mahoosive compared to the one on my old sx lol) so 14psi on the stock rb20det turbo? once i have a bigger turbo etc and all mapped up, what psi can i take the engine up to before it starts to lift the head etc?
Again, 14psi is only a guide so don't blame me if the turbo poops itself at that boost lol... but it could also run more and be fine. The higher the boost, the more risk there is.

Sorry mate, I have no idea on the upper limits of the 20DET in relation to boost/power etc. My guess is the head gasket would be the first weak spot to show, but I'm not sure what max boost level it's good for




...and as promised, pics :D
but first a few points - you won't need to cut the bumper iron nearly as much as I did... I cut it with the plan of cutting the bumper too but then I opted for a more stealth/factory look so mounted the fmic back as far as possible.
The brackets on the top side of the intercooler were made by me (I get asked that a lot lol), it's just alloy flat bar cut and bent to suit - tis cheap stuff too (2m of it cost me about the same as a new oil filter, I got it from my local hardware store). Bottom brackets were supplied with the fmic kit.
Don't try and mimic the piping on the drivers side, mine has been modified to fit the front facing plenum (different angles etc)
You will see part of an air intake in some pics.... I made a thread about making a cold air box and intake here (recommended mod with a POD, without it a POD is pretty much a waste of time) http://www.skylineowners.com/forum/showthread.php?t=157838



















 

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Everybody knows that the bird is the word
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9,198 Posts
mines exactly the same colour btw, its good to see how itll look with a huge intercooler in the nose =)
Here is a better front end pic for ya :)


 

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Cambridgeshire
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1,604 Posts
my 32 is on a tired old rb20.. i just bolted on a t38 ebay special .. added a 360bearing properly pinned and sent it off to be balanced..

chomped a hole in the housing to fit external gate..

threw together a downpipe and an inlet system..

at 18psi it is as quick as my good friends 380hp rb25 S13.. (he is on 3.9 diff, im on 4.1)

so i reckon im at about 350hp with it.. its my daily work pig.. i beat its head in everyday and its fine..

oh.. its on a Link ecu... shameless plug..
 

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Everybody knows that the bird is the word
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