recently got the turbo removed from my 1994 4 door R33 RB25DET.

having allot of problems with its performance now, the engine runs perfect, doesnt over heat even on long distances (i drove it on the freeway for over 3 hours) but changing of gears is drastic, first gear when i take off it grinds even with my clutch all the way out when i change into second it does the same thing but it feels heavier (kind of sounds like somethings loose and rattling around) after 2nd gear it starts to run a little better no grinding sounds or anything but it still backfires and makes noises, then when i go around corners it feels like somethings not right like the cars about to roll over, it seems like the car is to heavy for the engine even tho i know the engine is a great engine because when the turbo was in there it ran roughly 290 horsepower. i have another r33 that has the exact same engine and it runs a trillion times better, kind of thinking the car might not have been tuned to suit the stock engine and is still trying to find the extra power that is clearly not there anymore, is it worth getting a dyno tune done on my car? or if theres any other problems people might know that i can work around please let me know..
thanks.

ps got my tuebo removed because of p plate laws in victoria. not worth the risk.

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Please tell me you replaced your ecu with the non turbo ecu....

if not, thats your problem with running poorly... you car still thinks it has a turbo... and is accommodating the amount of air/fuel it puts into the engine.

Also, your car will feel slugish, as your compression ratio is lower then an N/A skylines (due to the turbo)... id be surprised if you could beat an excel.

Interms of not feeling right and clutch etc... im assuming you got it done by a mechanic? if so, have you mentioned the other things to them? I dont think they are related unless they took out your motor to de turbo it... which wouldnt be neccessary

Huge waste of money. You will still get in trouble for driving it because the vin number will state it still is a gts-t, as will the rego...

You were so much better off just buying an NA from the start, just because you took the turbo out, it doesn't mean it will be like an NA, it's not gonna have the same power as an NA (in a bad way) lol.

the origional plan with the mechanic was to get hold of a standard manifold and ecu, had allot of trouble searching, mechanic rings me one day and says he has another idea, take out the turbo and run the pod straight into the manifold and in he's words it should still read boost okay, so to answer your question, no it still has the turbo ECU in it, looking for a standard one, but there not easy to find. basically all i want to do is get my car to run like a normal car, not to worried about speed and boost right now, i just want it to be comfortable to drive.

as for the 2nd comment, i was talking to the lady at vicroads and she said i will be fine because all police personnel are trained to understand things like car engines, even if my vin number classifies my car as a GTS-T not a GTS, the officer on site is going to realise my car is non-turboed just by looking for the intercooler and piping running to the turbo, if theres no 2nd source of air intake im legally allowed to drive it.. were only allowed one source of air intake.

yeh was basically going to wait another 10 months before i drive it, so then i wouldnt have to worry about getting the turbo removed, i only bought the car because its mint as, and i talked the lady down $3,500 so it was well worth it, at the end of the day im not heaps worried turbo is going back in in 10 months, till then ill just deal with it and do what i can to make it run okay.

Exactly what I was thinking! On a related note, I've got a stock NA 33 ECU sitting here from when I did my +T conversion... for sale


This is very true as well. When I did the +T conversion, the higher compression ratio made it a decent amount more 'punchy' down low than other stock gts-t's... limits the amount of top-end boost I can push in there but yeah, just taking off the turbo and leaving the low compression rate will leave you with an engine that is simply not how it's designed to run.

i understand what you mean by just taking the turbo off will make the car not run how its designed to, i am kind of new to this, but i just dont see how i cant take the engine to a previous step, because once in this cars life there was a time when it ran stock. i just wonna know what i need to do to make it run stock standard again, should i take it back to my mechanic and get other parts? or is it not worth the money?

Okay.

RB25DE and RB25DET are NOT the same engine with a turbo strapped to the side of one. The DE runs a 10:1 compression ratio inside, the DET runs a 9:1. This is to allow for the extra air/fuel being crammed into the cylinders and helps reduce detonation/pinging. When you removed the turbo, you effectively produced a NA engine with low compression. The lower compression results in lower torque. On the DET, you've got the turbo to help out in this regard, adding the missing power/torque that is lost through the low compression. on the DE, the stock compression is higher to compensate for no turbo.

I'd change the ECU to a N/A item anyway to provide better fuel economy and power, though certainly don't expect the same power/response as a stock N/A R33... it's just not the same engine. If you're planning on re-turboing in the future, then I'd just do that and leave it there... it's not actually possible to 'tune' the factory R33 ECU (turbo or N/A), so you'd need to buy an aftermarket ECU (either copgyback such as the GReddy eManage or replacement such as the APEXi PowerFC) and then get that tuned... for the tiny gains over stock I wouldn't think it would be worth the cash.

Upping the compression isn't something you can just bolt on or off... the actual pistons in a stock RB25DET are slightly smaller than the RB25DE items, resulting in the lower compression...

yeah, that answers allot of questions, one would think my mechanic would have enough brains to work this out before taking my turbo off, coz im thinking i might put the turbo back in, hide it and just try my hardest to get away with it over the next 10 months, it was actually hidden before i got it removed, you can tell in the pictures i have in my account. do you think id get done for it?

Yes, id be concerned about the IQ of my mechanic if he did that too (my mechanic is me most of the time )

Also, if cops want to be asH*les they will, and even though there clearly is no turbo on the side of your car, they can say well, you have hidden it from us because your car clearly has it stamped on it as gtst.... so theres nothing u can do there...

As for conceling it, I drove for over 2/3s of my p's with a turbo and a fair few mods on... hid it with a little custom heat shielding... still got defected once (cop wanted to be an ass) ... but the point is that as long as theres no whistles and hisses from an aftermarket BOV and u drive sensibily... you should be ok... better then driving a tractor of a skyline for 10 months imo...

PLZ GET A standard N/A ecu... go to wreckers... look on this site... ppl have them... u just gotta look... it will atleast solve a few of your problems.

Now, why not try something like this :

i wish my mechanic was me most of the time, i am still in the process of learning.
i may as well try and hide it if cops can snag me weather its there or not at least i have a leg to stand on if i hide it, there not gonna see it either way so whats the difference, only thing is i dont think it will be an easy job to hide all the piping, intercooler, if they can see 2 sources of air intake they will know i have more air boosting my engine then im allowed to.
im actually looking for an aftermarket standard ECU at the moment, someone told me its not actually possible to tune a factory ECU so id have to find an aftermarket one, ive used like 3 quaters of a tank in 4 days and ive barley been driving so im gonna have to get this done soon..

i would recommend getting a new mechanic.
the DE and DET of their respective cubic capacity are physically different internally. its not as easy as turbo on turbo off

yeah this thread is full of stupid (not from the people posting saying that it was a bad idea though).

to the original poster, if you were to put your car on a dyno you'd probably find that you are making about 20kw less than a stock non turbo skyline, if not more (than 20kw less).

the mechanic who did this for you is both smart and stupid at the same time. he is smart in the respect that he did this for you and you paid him to do it so he got money, and then you will keep paying him to get it running better, but he is stupid for not telling you that the car would run like arse when it's done.

also i don't really think that putting a NA ecu in there will do much good as it is still going to be tuned for the higher compression. i think the best thing you can do is put the turbo back on and either park it for 10 months until you can legally drive it, or sell it and buy a cheap run around to drive for the next 10 months (and learn more about cars with) and then get a turbo once you can legally drive it, and have more knowledge about cars.

I agree, put the turbo back on and wait 10 months until you can legally drive it!!

Good luck!

a RB25det doesnt even run 9:1 its less ! haha 8:5:1

i have RB25DE pistons sitting about 5 meters away from me now when i did my 2.7L conversion. Change the rings to ACL racing series rings and TAADAA!!!! You will be wasting money just reversing what you have just done. Look into making a high compression turbo engine (much better turbo street car). If you want to learn do it on a RB25 because its a very easy engine to work on.

If you put NA pistons in and a ECU (NA one) keep your turbo ECU then after 10 months put the turbo back on and run 6psi and you will have heaps of response compared to the other GTS-t's.......Pistons are cheep (second hand good condition) (ECU's are cheap) labour is a fair bit and RB25's are very easy engines to work on so you better learn how deal with them if you want to get away with some money.

okay,
well luckily i own another r33 skyline RB25DE, it runs really good. so i can use this to get around while my DET is getting worked on..
to the last comment, what your saying is if i get non turbo pistons to replace the turbo pistons and a non turbo or aftermarket non turbo ECU and get it tuned my car will run like a non turbo RB25DE, lifting the compression to normal for a DE. and in a year when i get off my p's, put the turbo back in the car will be running like a RB25DE which has a higher compression ratio but on top of that it will have the turbo? i dunno why no ones brought this up, clearly its the best idea, who in my situation wouldn't do that? if the cars only going to run better in the end anyway..

btw if anyone wants to buy a 93' R33 RB25DE (gunmetal grey) ill be selling it early next year, done like 135,000 kays never had a problem.

Y didnt u ever mention it before that u have an N/A Skyline aswell!

U could go for all the extra effort now, changing pistons, paying for more labour, and no, not a bad idea if u want to drive the de turboed car normally for a while... but remember how I told u that cops can still say that the rego and compliance plates still say its a GTST and u still can get done...

WHY would u bother? drive the n/a.... if u want to really increase the compression on the gtst after ur off ur p's then fine...

This is kinda what I did... i.e. converted my RB25DE to a turbo... RB25DE+T... high compression pistons, etc. I threw i an RB25DET ECU and then retarded the timing a few degrees to help prevent detonation.
The thing to remember is because of the already high compression, you're quite limited in the amount of boost you can run... i.e. 5 or 6 PSI would be about it... maybe a couple more but you'd need it to be tuned pretty carefully to make sure things didn't go bang... and that means an aftermarket ECU (or copgyback - that's what I did with a GReddy eManage).
The other thing to consider, is that if you won't be changing the pistons yourself, i.e. you are paying someone to do the engine rebuild, it can get pretty expensive... I'd estimate around the $3-4K mark for drive-in/drive-out service,

In the end, if you've got an N/A skyline, just drive that for the time being and then keep the gts-t setup as it was designed for when you can drive it.

Sam's spot on

RB25DE pistons
RB25DE ECU
Tune
(you will have your NA)

If you end up putting NA stuff in the engine keep all that in the engine so you wont have to spend MORE money!!!. Then put a turbo back on and use your old ECU with a Apexi power FC or E-manage, (you will need to keep a good tune through a copyback) boost controller will be handy to adjust turbo settings to 6PSI (yeah not much as stated by sam or the engine will really go BOOM) keep it this way and you have a GTS-t that got high compression so you can take off without that turbo sluggish start and still gain some power from a turbo (best for street use because of the response being more easier to drive with and the turbo is really responsive aswell so it all ends up making a good daily driver).

Other than that drive the other NA around for now and just reverse what has been done to the GTS-t ........... bit of a waste to do that i think.