P1 2.5 conversion!
 

Hi I'm new to ther forum, last Saturday I bought an rb320 110# after owning the car for this short period I love it! So immediately I want more power but I can't justify modifying a sought after car like this.. So I'm thinking if buying a P1 and getting the more power out of that, I understand that the P1 and the Rb have near enough the same 0-60 and even the p1 maybe slightly quicker, to get to the point I want to purchase a p1 and thinking of converting it to 2.5T.. I'm sure it's possible because anythings possible but just reading that the ej20 and 25 are basically the same just a bigger bore etc.. Please help!!

Why would you bother? Rip out the rubbish 2.5 and put a 2.0 in there instead and save yourself the hassle of it popping

:wonder:

Glanza that has to be the worse advice given his question I have read for some time.

So rip out a 2.5 engine from a limited run car install a 2.0 although he has no issues with the 2.5 ?

If I was to modify the 2.5 RB320, I would pop in some forged pistons, and a decent turbo, remap for 400/450 without tsaking value out of the car.

If you read his post he wants to buy a P1 to put a 2.5 in it ;)

So that has to be the worst idea ever, rip out a decent 2.0 and put a rubbish 2,5 in it?!?!

im sure i commented on this earlyer but it seems to of vanished,o well if yr interested in modding a p1 then its all been done on the p1woc

i wouldnt bother with a 2.5 either

Curious question to the 2.5 haters have you driven both at forged 2.0 + 2.5 running similar set ups?

i dont hate the 2.5 and no i havnt driven a modded 2.5 i believe the engine is down to what you want from the car and the 2.5 isnt for me but may suit the op

That's the point I was getting at, a forged 2.5 would make a better road car than a 2.0.

A good 2.0 for the road at 400/400 is nice, however a 2.5 with similar mods at 450/500 makes such a better experience in my opinion, a 2.1 or 2.35 are clearly an option that are not to be dismissed depending on the OP's credit :D

ive got the 2.1 wish id just forged a 2ltr

I would read up on the 2.5s ;) they shouldn't be given big boost etc.

I have driven both, and to be honest I would rather have the revvier 2.0 and not have to worry about it crapping its self every time I show it the loud pedal!

as above

Thanks for all the replies all .. The reason why I want the 2.5 is for obviously because of more displacement, and the torque is much better , should I bore out the ej20 in the p1 and go from there ? I understand that a p1 has just as much heritage as the Rb but the fact is there's maybe less than 290 rb's and probably treble the amount of p1's knocking about , but I'll have a look on the p1 forum what someone's linked me to

Can't find any ej25 p1 conversions on p1woc 😞

there isnt many but there a few with 2.5

Don't bother with a 2.5 engine mate, unless you have a monster turbo or twin turbo on it you will get uncontrollable boostcreep once you start making the exhaust less restrictive.

What's the most u can bore the ej20 block the p1 comes with ? Is it 2.3? 2.2? And I'm sure I've heard of ppl using 2.5 bottom end with ej20 heads ?

std 2.0 block can be stroked to give 2.1 but otherwise its a re-liner job to give different capacity (easier and more cost effective to simply buy the correct block first IMO)

2.5's can be made to work very well depending on your exact project/aims/budget

something like this helps greatly

https://www.facebook.com/ASPerforman...type=3&theater

All this slating on 2.5s yet they make for a very good setup, yes the standard pistons are Sh!te, but if you were going to put a 2.5 in anything as a project then surely you'd drop in some forged pistons and a decent set of gaskets?

I ran a 2.1 stroker and around 500/475? which was a nice weapon, I can't be sure on the torque figures but it pulled very well, much more so than a 2.0, but then it had the right accompanying bolt ons with it.

A forged 2.0 makes a nice revving motor too, some have seen excess of 600bhp through a well built/spec 2.0.

Sat as a passenger and driven a 2.5 at around 450/500 and it is quite a different beast to how my 2.0 at 430/400 felt.

To the OP I would sit in so e variation to get so e idea of what you would like, but don't forget the classic will weigh too fatty passengers less than your RB320. So that said standard RB320 V standard P1 in a straight line and twisties will probably favour the P1.

Rob

Big boost is needed on a 2.0 to get the larger turbos up and running. Not something I've found with the 2.5.

Because no one dare take a 2.5 above 1.4bar ;)

have no lag issues on my 2.1 at all to be honest,

Is that the most u can bore the ej20 out to ? 2.1? Or is it 2.3?

So you're on a 2.1 you're not playing fair ;)

So please don't take this as a dig or in the wrong way just if you haven't driven one how can you say it's no good (in forged state) how do you know it's not for you and how can you offer an opinion with nothing to base it on

Driven plenty of 2.0s with no lagisssues either ;) If you have a proper turbo 100cc isnt really going to make much odds ;)

Oh, and i dont play fair FWIW!

Your not boring a 2L out your changing the stroke of the crank to give it 2.1, to get a 2.35 you need a 2.2 block or fitting liners to a 2l block just for info i hope your planning on improving the transmission as the tourqe of a 2.5 will quickly kill a 5 speed box

Both a forged. 2.0 or 2.5 on a sc46,

which set up spools earlier,
makes more mid range torque
and has a higher out put and only requires 1.4 bar ;-)

yet the 2.5 is a sh1te lump as a road car and yes I've had both, driven both and as a daily driver would pick the 2.5 everytime

Now a standard 2.5 that's a different story, if I wanted to add bolt on Mods then fine the 2.0 is the way forward yet not one from a p1/clsssic it would have to be a new age 2.0 so either way the engine in the OP's project car would be coming out

Not necessarily though... Its all about the graph of the turbo, CFM's v pressures etc.

My turbo has seen 2bar plus on my 2.0, put a 2.5 on that and watch it explode wether forged or not ;)

Your missing the point.......

Where has the OP talked about running 2bar, in fact he's only mentioned wanting the bigger sized engine.

2.0 at 2 bar or 2.5 at 1.5 bar, depending on the setup an equal amount of power can be had from both, and probably more torque in the 2.5.

I'm not saying the 2.5 is the better choice as it depends on OP's requirements for the car, but you can't dismiss the 2.5 as it might not like 2 bar. As said 450/500 is nice in a forged 2.5, it makes a lovely road car, loads of torque so less need to drop gears, and will out run most other cars on the road. The 2.0 is a very good revving engine, as said it needs to be from a newage 2001> STI though.

Rob

Yeah thanks for all the replies guys it's helping me a lot to make a decision but now I'm just thinking of why have 2 2.5's? Be good to both for the difference.. And also it's just gonna be a raod car maybe the odd Sunday track