To Convert Or Not...

[Cubes]

i can beat a 5litre v8 5 speed in my rb25det 5speed

We have to compare apples with apples. My old 5ltr V8 5speed felt laggier below 3000rpm than what a RB25DET does. As soon as 3000rpm came along it would pick up start to chirp the wheels in first and scream off to 70km/h before clicking second. Thats my second point. Gearing. The R33 will or should have a higher spread of power in any gear due to its shorter gearing.

My old Commodore would click third at ~120km/h. It had a little bit of work done so it rev'd a bit harder. but still its slower than the skyline due to its poxy factory gearing. Launching out of corners in the line is much more fun and quicker with the wheels struggling for traction where as the commodore felt like it had a much narrower powerband and due to its gearing third gear was to long and second was to short.

My R32 when it was stock used to beat my mates VT LS1 SS Auto. Only just but it would constantly slowly pull away, not by much though as he was always next to me right up until around 185km/h where my speed limit kicked.

[slip]

Genesis - Fair bit of time as I built the car from a wreck (fell asleep) and a shell.

Its been through a few stages of specification, but on the current spec, i've had the rear suspension out, dissasembled, reassembled and reinstalled myself about 7 times, brakes took thousands and a couple of months, the whole dash has been out of the car, did the waterpump in the repco car park at warwick in the dark (thank god for people who bring tools to track days), installed swaybars and strut brace, and just HEAPS of general working on it/removing something to get at something else, little custom things blah blah. And at the end i've just got a gutless 31 that stops hard and is alright around corners (I still want different wheels and lower springs, it never ends).

Start with a good car in the first place!

[paulr33]

Joel: I agree with your points.

However there are many factors that affect one car and another. A broad statement such as my "my gtst 5 speed beats a vb 5 litre" doesn't really prove or provide much info, more of a generalisation.

In my experience, went from VL 3litre non turbo auto to gtst 5 speed that forced induction is a massive massive increase on throughput. Within a second of full acceleration I hit the stock boost limit of 5psi up till 4500rpm then the boost limit jumps to 7psi all the way to red line. You can feel this jump in any gear. Even of the freeway sit at 100, just 1 dot below 3000rpm and floor it in 5th, boost comes on instantly due to high exhaust flow and yer away . Kick back into 4th and get the revs past 4500rpm and you'll fang off.

My car is stock. Pod filter is only mod

Get a boost controller and remove the factory boost limit and run 10psi the whole and its probably a further 20% increase on the current gtst performance. Again these are rough figures. My advice is to sell and buy a turbo'd model.

9/10 times youll find the conversion isn't worth it

There are of course, exceptions such as if your a car mechanic or like learning and so on

[paulr33]

Of course im only going off what I nkow and hear etc.. I dont personally know 10 people that have done the conversion and 9 of them said its crap

But i do sympathise, when i had my vl i wanted to strap a turbo on it to so many times. but then you find you need a new ecu, brakes, injectors and other shit

[Genesis®]

slip - you did that time and time again to get that perfect handling that you craved for din you?

paulr33 - what did the 9 outa 10 ppl ended doing with their converted cars?

[paulr33]

oh nah im was just saying as a figure or speech. it wasnt factual evidence, hearsay. i was saying that 9 out of 10 probably wouldnt do it in the end

[slip]

I did it a few times then realised some idiot had 1 side set up incorrectly with a plate upside down causing them to be different heights. Then to swap springs i think, then swapped springs back, then to adjust them again, then to readjust them after the fronts were changed.

So no, not really to get that perfect handling, it was just out of necessity. I should probably put the std rear swaybar back on for more grip and corner speed but its more fun with the rear slightly easier to bring around. (no lsd.... booooo) Car still needs 2 major and 1 minor changes to the suspension setup to be good. Stock 03 RS Impreza (wrx like wheels/susp) shits all over it in back to back testing.

[pstanbis]

"If you really like your car, then go for the conversion..".if not buy a gts-t and whack an RB25DET in it.

Dan

- just quickly, who here doesn't really like their car ? anyone? didn't think so.

Ok, main question is, given the cost of a 20det/25det, and the lack of any market for selling on the old 20de, is it really feasible to swap the engines out or as most people suggest, just trade the car? Each has its merits, but lets face it what we all strive to be is different - and to save some money while getting high horsepower, but we can't have it all - so why not go all out and just change the crank/conrods in the original RB20de (in my case) and bolt on the turbo to the original engine? im sure there would be some problems with that ridiculously simple comment, but would it work? here is where the call goes out to any tech minded uys who have experience with this stuff - Is it that difficult to turbo a N/A engine? ive seen a few kits for other cars that are just "bolt on" but to what extent ? and would it be that simple with the RB's, as they are a pretty solid engine to start with?

Just a few thoughts, as someone suggested to me today that i should get a turbo, but im kinda attached to my baby, so what can we do?

[Genesis®]

pstanbis - if you do the bolt on, read the following thread: http://www.skylinesaustralia.com/forums/sh...ead.php?t=30992

i know what you mean by being attached to your car. that is why i started this thread in the first place becos i wanna heard other member's experiences/views/comments as well. there are alot of pros and cons that you have to take into consideration. at the end of the day, its your car and your wallet.

glenn

[slip]

Its the pistons that give the different compression ratio, not the crank and rods pstanbis.

[VIPERGTSR01]

just get a GTSt front cut and swap engines, ecu etc

[Ryno]

There's not much point in trying to slap a turbo onto a non-turbo engine, given that half cuts are so cheap.

It will cost around $2500 (incl labour) to drop a RB20DET in or $4000 to put a RB25DET into a R32.

If you were to try and put a turbo onto your non turbo motor, you will have to buy:

Turbo ($1000),

Manifold + Dump pipes ($500),

Intercooler and piping ($500),

New pistons ($????),

Head gasket ($200)

plus labour to pull the engine apart to install the new pistons, and drop it back into the car... Then once this is all together, you may find the new computer/injectors/fuel pump aren't up to the task of running it all.

It's far easier and cheaper to simply swap the engine, with parts from a half/front cut.

Ryno

[Genesis®]

i agree with Ryno.

[pstanbis]

This is true - it would probably make more sense given all the mods needed to just get the half cut, but is there anyway of telling what kind of Kms the engines done? it may have been pulled out of a hoons car, which is why it was written off in the first place. Also, how compatible are the wiring harnesses, coz i've done a few engine swaps before, all but one were carbies, not EFI, and hence no computers, but the one with an ECU to negotiate cost me 5/600 for a custom wiring harness - and how different are the ECUs on N/A - Turbos?

[Genesis®]

to the best of my knowledge:

buying a front is totally dependable on your luck. some may have been taken off from cars that had serious crashes at the back but the owner decided to write it off. only of the signs of of overused are engine wear, worn belts, dried oil, rust, etc. once an NA car has been coverted, a new ECU is preferred to cope with the additional km output.

as for the wiring harness, i dun really noe much abt that so no comments from me.

glenn

[Cubes]

pstanbis,

I don't think its 'striving to be different' its more I have a lead foot and I want to use it. I like speed and I want to speed, I want to have the smirk on my face after I suck the doors off that loopy idling V8. Thats what I like.

I don't like lag, I don't like waiting for boost to kick in first gear, I want to put my foot down and I want the car to pick up and go not wait until I'm at his rear guard then have to play catch up. Hence RB30DET.

If you have the RB25DE head grab your self a RB30E short motor get a cheap rebuild or if the motor is still in good nick simply bolt it straight in under the RB25DE head.

Maybe its just me... I don't like the lack of torque from the RB20DET. I've came from my first car a mild TE 250 4 Speed that you could idle away from the line chirping the wheels, then a 3ltr 5 speed which was a less gutsy down low but still could accelerate quickly from low revs, then a VS 5ltr 5 speed commodore which funny enough had less guts down low compared to the TE & VL. Maybe it was the gearing & the few mods it had.

One word.. Don't go for a RB20DET, do it properly the first time and you won't waste money. Either build up a RB30E bottom end even if its a stock bottom end for around 1-1.5k, slap the RB25DE head on or go for a RB25DET motor which at the end of the day if you are eventually going to go forged pistons the RB30 will be cheaper as you will have to rip the RB25DET apart anyhow.

[pstanbis]

Well my first (and only) other car was a '86 Subabru L-Series 3spd Auto, so i don't have a heck of a lot of comparison room here....

However, i do agree with your point about torque. Lets face it, most, if not all, smaller capacity Jap engines just aren't gonna have that low-end, step-off-the-clutch-at-idle kinda torque that big bore V8's generate. Its just not possible. To get em going, you gotta have revs - lots of revs - hence the reason Early 90's V8s redline about - 5/5.5 thou? (correct me if im wrong) and an RB20DE of the same age cuts out at 7.5 ! Sure, thats all well and good once or twice a week for a bit of fun, but you can't drive it like that EVERY DAY and expect it to last more than a few years (if your lucky). So the RB30 certainly sounds like a nice sort of trade off. (assuming they don't rev as easily as the RB20/25, otherwaise its all gain) But surely ther are more mods that just "Get a short RB30 and bolt on the RB25 Head" ? Oil galleries, dowels etc - they've gotta be a little different...?

[Cubes]

pstanbis,

Oil galleries, dowels etc - they've gotta be a little different...?

If you use the R32 GTS RB25DE head the oil/water galleys & bore size are all exactly the same as a RB30E's. The R33 RB25DE/T has a small difference in one of the oil/water galleys due to the oil feed for the R33's VCT. This can be easily worked around.

Everything bolts up perfectly.

[slip]

pstanbis - you worry about getting a motor thats been in a 'hoon car'.

Show me an RB thats had a genuine easy life, and ill show you 100 that have been driven hard.

[pstanbis]

Show me an RB thats had a genuine easy life, and ill show you 100 that have been driven hard.

Yeah, yeah, i know, RB's are made to go hard, why else would you buy a sports car? And your right, 1:100 is about right, im aware of that, i was just thinking of major stuff, burnt valves, stressed rods, etc. which i imagine wouldn't occur in RB engines until they'd been raced for a while, or dragged or whatever. And as a general rule, if you get an engine that has no mods to it, i don't think there'd be much you could do to hurt it in anyway - and lets face it, Nissan wouldn't have made a motor that you could kill easily in it's factory state, now would they?

All it comes down to is that i've been stung once like that and im just paranoid now...