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Discussion Starter #1 (Edited by Moderator)
hi all, ive spent most of the day looking for tuning info but not really got that far.
could every one with a rb25det right a little list of there engine mods and bhp and boost there running?
how many are running apexi fc ecu`s?
i spoke to some one at rising sun performance and there may be a group buy and mapping deal going on soon if theres enough intrest there.
any info on tuning the rb25det would be very much appreciated.

i found a tuning guide for the rb26dett but it seems this dont really apply to the rb25det engine.

hope this thread will help all other un-sure rb25det owners.

so far i have:
fmic
walbro fuel pump
mesh airfilter
3" downpipe back
stock boost

im stuck on:
when the ecu needs upgrading
when the turbo needs upgrading
when the clutch needs upgrading
when the head gasket needs upgrading
when the injectors needs upgrading
when the airflow meter needs upgrading
when the cams need upgrading
when the pistons need upgrading

any other parts that need upgrading that i missed?


what are the options for each of the above?
at what boost/bhp do the above need upgrading?
how much should i expect to pay new and 2ed parts?
will any of the parts from the gtr rb26dett that will fit as a direct upgrade?

all help and advice will be very much appreciated!!
thank you every one for taking the time to read and reply to this.
 

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I have:

Apexi Induction kit
Splitfire coils
Apexi AVCR (0.9bar) - spare turbo waiting just in case!
Apexi AFC Neo (mapped by Jez Horsham)
Full exhaust system (decat and all)

The next step for me will be:

Front mount cooler
ECU that allows finer control and ignition control as well (also removal of maf)
Bigger turbo
Injectors
Remap (obviously)
Probably colder plugs too
Fuel pump

Head gasket iirc doesnt need changing unless you run over 1.2bar (someone will correct me im sure)


I suppose the real question is - what power levels are you looking at.. then people can best advise.
 

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when the ecu needs upgradingaround 300bhp
when the turbo needs upgradingwhen you want to run 330bhp or 0.85bar
when the clutch needs upgrading340bhp
when the head gasket needs upgradingwhen you want to run more than 1.2bar
when the injectors needs upgradingover 330bhp or 0.85bar
when the airflow meter needs upgradingsame as injectors
when the cams need upgradingno set time, just always a good power mod once you finished with everything else.
when the pistons need upgradingover 500bhp
 

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Discussion Starter #4
not sure what bhp i want for now, i want to end up with 450bhp at the end of it but can not afford all the modifcation yet, hence i need a list, i dont want to go buy a piggy back ecu if ive only got to pay out agian 3mths down the road for a apexi fc ecu, if that makes sence.
i cant afford to start off with 450bhp so want to start with:
300bhp then 350, may then to 400 then to 450bhp im not sure to be exact but depends what mods with out buying bits twice, rather get each part i need for 450bhp but so i can run the in between bhp.
does that make sence ive been up 16hrs and looking at this screen for 8hrs of them,lol
 

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No worries.

My next mods if i was you would be a Greddy profec B II boost controller and set boost to 0.80bar and a Apex-i power fc.

You might find when you wind the boost up that the plugs (if running std) and coil packs might give up.

After there it get expensive as injectors, AFM, clutch and turbo all give out at the same point so get saving and decide what power you want.
 

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Discussion Starter #7 (Edited)
cheers bruce ill get saving now then,lol
so basicicaly you would recomend tuning a rb25det in this order:
stock rb25det ........250bhp

mesh air filter
3" turbo back + de-cat
front mount intercooler
walbro fuel pump ..............280bhp

electronic boost controller set a 0.80bar
apexi power fc ecu or safc (fuel controller)
splitfire coil packs
idruim spark plugs .........330bhp ish

injectors, AFM, clutch and turbo depending on spec = 340-450bhp
 

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I have...

HKS filter,
Nismo airflow meter,
Xs power tubular manifold,
750cc injectors,
HKS GT2535 turbo,
HKS pistons,
Uprated fuel pump,
ARC front mount intercooler,
Apexi power FC + Hand commander,
Kakimoto exhaust system,
Xspower downpipe,

(thats all i can think of off the top of my head)

0.9 bar [email protected]
1.1 bar [email protected]

havin the car remapped with power runs this weekend so ill have some more upto date figures coming soon
 

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when the head gasket needs upgradingwhen you want to run more than 1.2bar
This might be a stupid question, but how would changing the turbo affect this?

I mean if you fit a bigger turbo, but still run it at less than 1.2bar, would the HG still need changing on the basis the turbo will be flowing more air at a given boost pressure?
 

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This might be a stupid question, but how would changing the turbo affect this?

I mean if you fit a bigger turbo, but still run it at less than 1.2bar, would the HG still need changing on the basis the turbo will be flowing more air at a given boost pressure?
As far as I'm aware turbo size won't affect it at all, as long as you keep it to 1.2 bar and under.
 

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Discussion Starter #12
if i remember correctly a larger turbo flows more air, so if you run a stock turbo .80 bar and then replace the turbo for a larger turbo set at the same boost it still flow a larger amount of air at the same pressure. correct me if im wrong.
 

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if i remember correctly a larger turbo flows more air, so if you run a stock turbo .80 bar and then replace the turbo for a larger turbo set at the same boost it still flow a larger amount of air at the same pressure. correct me if im wrong.
makes senso to me , but its the boost level that dictates when the headgasket goes pop, standard gasket holds up to 1.2 bar regardless if you're running a standard tubby or a T88
 

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cheers bruce ill get saving now then,lol
so basicicaly you would recomend tuning a rb25det in this order:
stock rb25det ........250bhp

mesh air filter
3" turbo back + de-cat
front mount intercooler
walbro fuel pump ..............280bhp

electronic boost controller set a 0.80bar
apexi power fc ecu
splitfire coil packs
idruim spark plugs .........330bhp ish

injectors, AFM, clutch and turbo depending on spec = 340-450bhp
Spot on mate, and after that head gasket if you want even more out of your turbo or some cams.


I have...

HKS filter,
Nismo airflow meter,
Xs power tubular manifold,
750cc injectors,
HKS GT2535 turbo,
HKS pistons,
Uprated fuel pump,
ARC front mount intercooler,
Apexi power FC + Hand commander,
Kakimoto exhaust system,
Xspower downpipe,

(thats all i can think of off the top of my head)

0.9 bar [email protected]
1.1 bar [email protected]

havin the car remapped with power runs this weekend so ill have some more upto date figures coming soon

How do find the XS power manifold bud, your prob the first person i know with actual hands on experience with one.


if i remember correctly a larger turbo flows more air, so if you run a stock turbo .80 bar and then replace the turbo for a larger turbo set at the same boost it still flow a larger amount of air at the same pressure. correct me if im wrong.
Your right there bud, but its not the power that creates the probs but the actual pressure from the boost that kills the head gasket.
 

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how can you rate the pistons so high ? I thought the ringlands and rings themselves were not really that good... Because the rings are too much to the top of the piston ?
 

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how can you rate the pistons so high ? I thought the ringlands and rings themselves were not really that good... Because the rings are too much to the top of the piston ?
People run 500bhp on the standard engines, i myself am running around 430bhp-450bhp and have been for 3 years.

Its also down to how well its set up.
 
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