Rb25Det To Rb25De

[cameron666]

I have a r33 gts-t at the moment and yes i want to make it a rb25de.

I have just found out that i have blown the head gasket, so i was just wondering if anyone would know if i can shave the head and run a thin head gasket to get the comp to at least 10:5:1 at least.

I have a powerfc wired up to my stock 25det loom already so thats why i was just gonna make this motor a DE.

thanks

[eightsixboy]

Prob a lot easier and cheaper to sell the motor as a det and buy a neo n/a motor, I wouldn't bother getting anything machined.

It can be done though, don't see why not, there should be a lot of different thickness head gaskets available for the rb25, just don't go crazy skimming the head, don't want to take to much off.

[cameron666]

Prob a lot easier and cheaper to sell the motor as a det and buy a neo n/a motor, I wouldn't bother getting anything machined.

It can be done though, don't see why not, there should be a lot of different thickness head gaskets available for the rb25, just don't go crazy skimming the head, don't want to take to much off.

Its just would be better for me to keeep the det as i have a pfc already wired up to it. so i save money there.

I was just worried about clearences when i shave the head and run a thinner gasket and if it would make an issue?

[niZmO_Man]

By the time you're done what you're planning, you could have thrown an N/A NEO6 in there for less. I've seen good RB25DE's go for $500.

Cost vs. time. Remember that machining work and parts will cost you $1k easily. Pretty sure that you'll have to change the pistons to get it to the 10:1 mark.

[MBS206]

If you're going to downgrade, you might as well downgrade properly and put an LS1 in it...

[Bennis]

Why would you want to downgrade?

[Dose Pipe Sutututu]

he's probably on a restricted license

and what you're doing is a complete waste of time & money, just buy a N/A motor and drop it in - cheaper, faster, better

[bozodos]

these threads don't get locked on sight?

TL;DR, engine is incredibly low comp for N/A use, would need to be retuned, still run like shit, and depending on the state, still be illegal. Put N/A motor in or don't drive / sell / use as track car while on P's. Conversion has been done before, with the above mentioned results.

MBS206: you mean upgrade there pal

[StevenCJR31]

^^what a load of misinformed dribble, 9.0 to 1 isnt by any means "incredibly low comp" , it will run fine after a retune and it will be okay to run 91 ULP and wont run like shit at all

[Dose Pipe Sutututu]

headgasket + machining head + time/labour > buy 2nd hand N/A motor drop in

[MBS206]

^^what a load of misinformed dribble, 9.0 to 1 isnt by any means "incredibly low comp" , it will run fine after a retune and it will be okay to run 91 ULP and wont run like shit at all

Been done before, runs like shit.

It's not just comp that's different, but cam profiles etc etc.

[niZmO_Man]

Like drinking soup with a fork...

[StevenCJR31]

How will different cam profiles make it run like shit?

[bozodos]

9.0:1 in a 2.5 l engine is painful, don't know about the cam profiles, but someone actually had a thread with pics, and regretted wasting the time and money. Need I reiterate that you'd need it returned for its now horribly inefficient engine?

[StevenCJR31]

^^ yes I already know that it would need a retune (ive also agreed above on that point) 9.0 to 1 is plenty high enough for a na 2.5 litre and most other engines with efficient 4 valve and dohc designs heads. .engines can be de+t and det-t...

Im not arguing that its a waste of money. . . My point is that its achevable /doable

[Bennis]

If you are set on doing this then go speak to a mechanic and have them do it. Then report back and tell us how amazing the car is to drive

[Socrates]

My car was 8.5 CR N/A, nothing wrong with that, 2.4L

[MBS206]

How will different cam profiles make it run like shit?

Cam profiles are designed pending certain applications, youll be completely changing how the exhaust flows and therefrore how the head and cams will breathe.

Kind of like shoving huge overlap cams in a V8 and then bitching the car wont idle like standard...

the engine is designed as one large system, that youre f**king with. It will drive, itll also make way less power than an RB25DE from the factory. There is a reason so many people have complained about driveability after doing this exact conversion...

[StevenCJR31]

^^hmm google must have it wrong then because it shows the cam profiles between the r33 rb25det and r33 rb25de are the same - 240 degrees duration and 7.8 mm lift on both inlet and exhaust

[bozodos]

Wikipedia said that, but it's hardly a reliable source. It can and has been done at least once, but for the dubious legality, costs involved, and results "gained" it's not worth it on a Skyline.