How-to: bolt a VLT turbo onto your RB25DET

[Revhead]

I've just done this myself and thought you guys could probably benefit from my mistakes Will post pics when I get them. I didn't get any pics of the build as my camera was flat and I wasn't going to wait around until it was charged... I was pretty keen!!

1. Try to source as many of the bolt-on bits for the VL turbo as you can, particularly the dump pipe. Oil/water lines would be handy too.

2. Obviously you'll need to compare the turbos, so remove both and put them side-by-side on a bench. Note the steel-wheeled goodness of the VLT compressor :aroused:

3. Note that the wastegate on the RB25 is built into the exhaust housing of the turbo, whereas it's in the dump pipe of the VL turbo. Cut the dump pipe shortly after where the wastegate section finishes, then machine it back so that it's a nice, flat piece of steel. You could weld this to the exhaust housing on the turbo, but I chose not to.

4. Using the freshly-cut wastegate section of the dump pipe as a template, cut a new flange for the R33 exhaust. Cut off the existing flange, weld the new one on, and clean it up with a dremel, being careful not to damage the oxy sensor (remove it if you can, otherwise stuff a clean rag down the pipe). Make SURE that the new flange is angled to sit flush on the back of the turbo - dummy fit to be certain. Mine was close but needed some work to stop exhaust leaks at the flange.

5. Rotate the housings so that everything sits the same as the stock RB25 turbo - oil return line should be on the bottom. Sit the wastegate section of the exhaust on the back of the turbo, and turn the intake housing until the wastegate actuator bolts on and can work the wastegate without binding on the wastegate shaft. Use the actuator from the RB25 turbo, as it has a bend in it to clear part of the snail. It will still foul on the turbo once the piping is in place - see next step.

6. You'll need to modify the bar on the wastegate actuator so that it clears the turbo - with the pipework and clamps in place. You'll need to reshape it so that it retains the same overall length, so that the wastegate opens/closes correctly.

7. Bolt the turbo to the exhaust manifold and fit the oil and water lines. Some of them will NOT fit - the one on the top of the turbo (as it sits when fitted) misses by a good inch or so. I tried bending it with a small pipe bender, but it ended up being easier to just break the piping a few inches from either end, flare the ends, and use some reinforced, high pressure, high temp hose. I used 5/16" hose that's intended for an oil cooler, and put a large loop in it to avoid kinking and damage to the hose after many hot/cold cycles. The line that comes from the back of the block falls in the right place, but needs to be rotated a few degrees to line up properly. The oil return line fits perfectly, though I replaced the hose with a new, slightly longer one for my own piece of mind. The stock heat shield no longer fits, so you can either delete it (I'll be making a replacement) or modify the mounts. If you remove it, you'll have to relocated the wiring for the oxygen sensor. I zip-tied mine to the aircon lines for the time being.

8. Notice the cast 90 degree bend on the factory R33 turbo? It bends 90 degrees with a twist in it, and also goes from 2.25" to 2" at the turbo. Naturally, it doesn't bolt onto the 'new' turbo, so I ended up using a piece of 2" pipe with a 90 deg mandrell bend from a local exhaust shop, and two short pieces of reinforced hose, one each of 2" and 2.25" ID. Make sure the pipe you get isn't going to rust or flake off into your intake - get it powdercoated if you're keen. Cut one end of the pipe almost up to the bend - it'll need to fit between the turbine outlet and the power steering reservoir with enough space to clamp the piece of 2" hose on properly. The other end connects to the factory intercooler plumbing using the 2.25" hose, with one end clamped down hard to make it fit the 2" pipe. Not pretty, but I'm replacing it in a couple of weeks when my intercooler arrives, so didn't see the point of making it showy for such a short period. When that arrives, I'll be making a new pipe from stainless, and the bend from the turbo will be made from two or three bends welded together to make a smooth curve with plenty of clearance.

9. The factory piping from the AFM will slip straight over the nose of the turbo. Sit the return pipe from the cooler in place and connect the wastegate back up. I changed bleed valves while I was at it, so I needed to modify the wastegate plumbing - if you do the same, plug any holes. My new turbo had a small fitting on the front of it too, put a bit of hose on that too and plug it. Reconnect the rest of the intake plumbing.

10. Bolt the exhaust up. The bolts from the VL turbo will hold, but only by about two threads in my case, due to the extra metal it has to go through (remember the exhaust flange??). I managed to find slightly longer replacements at a local nuts n bolts place. Finished? Not quite... on my car, the longer bolts wouldn't go into the holes because they fouled on the dump pipe, so I had to dremel a bit of a chamfer on three or four of the holes and drop the dump again to fit the bolts. Once that's all done, take it for a spin... mwuahaha

Notes

The turbo I used is a T3 with T4 internals and larger exhaust housing, so boost comes on much later than it would with a stock VL turbo. Don't forget that the RB25 is down 500mL on the VL engine so expect slightly more lag.

The car is completely different to drive. The turbo starts to whistle around 1300rpm, usable boost at around 3000, and a real power kick (like a light switch actually, woohoo ) at around 4500. There is absolutely no power drop as the redline approaches. The car makes noticeably more power at 10psi than it did with the old turbo and 13psi.

It needs the new intercooler pretty badly, it takes no time to heat-soak the stocker - around 5 or 10 sec of hard acceleration will do it. Apart from that, I'll be dialling in the cams to improve response and getting a PowerFC/Wolf/something to make sure it's all AOK - I'm taking it easy until then.

The exhaust is a little bit louder and slightly more droney, no doubt due to the larger/less restrictive exhaust housing on the new turbo. Also, that annoying 'whoosh' noise through the intake is gone, replaced by a proper turbo whistle.

I'll edit this post and add some pictures when I get 'em.

[rb20-calais]

good work

[Revhead]

Thanks I should clarify the lag thing. Between 3500 and 4500 it loses very little to the stock turbo, it's just that at 4500 it kicks in HARD

With the heatshield in place, you'd never know...

Closeup of the exhaust flange. I've since fixed the bolts but you see what I mean about the extra metal they have to go through and clearance against the dump pipe

Told you the turbo -> cooler pipe was a tight fit at the moment

Oxygen sensor out of the way

This is where the wastegate actuator fouls on the turbo. It's a bit hard to pick it here, but this is looking straight down on the wastegate actuator itself, and it's fouling on the outlet of the intake side of the turbo (if that makes sense)

Looks pretty stock - even the turbo still has "Nissan Motor" cast into it. Useful for those pesky roadside inpections...

[cameron]

Notes

The turbo I used is a T3 with T4 internals and larger exhaust housing, so boost comes on much later than it would with a stock VL turbo. Don't forget that the RB25 is down 500mL on the VL engine so expect slightly more lag.

The car is completely different to drive. The turbo starts to whistle around 1300rpm, usable boost at around 3000, and a real power kick (like a light switch actually, woohoo ) at around 4500. There is absolutely no power drop as the redline approaches. The car makes noticeably more power at 10psi than it did with the old turbo and 13psi..

Hey,

My bros got a 95' series 2 R33 gtst and his turbo sounds very similar to yours,

his turbo spools up at 2,500rpm and hits full boost at 4,500 (15psi) but kicks you back in your seat at 5,000rpm

have you got any more pics ?

Could you please describe more info on how your turbo works,

also whats the max boost you can run o yours... cause if we got the same we are running 15psi.. which is max it will go cause after 15psi it just over spins.. and goes no were but it hasent blown yet... after weve hit 20psi lots times

also as yours get closer to redline does your boost bleed off.. cause bros does after holding 15psi for a little bit it goes down to 10psi and we have turbosmart bleedvale.

Cheers,

Cameron

[Revhead]

What pics do you want? I won't be dismantling anything for at least a week or two (cooler arrives then) but I can get shots under the car of the piping, more mounting pics etc.

The turbo was rebuilt to run 25psi on a mate's VL Turbo wagon - as such it really comes into ats own over 1 bar. I'm not running anything like that (stock internals for now) but on the VL it would hold 22psi all the way to 7000rpm, and that's using the bleed valve shown in my pics. The reason I now have the turbo is that he cracked his block.

Be careful running 20psi on standard internals, particularly if you're not using programmable management...

[cameron]

What pics do you want? I won't be dismantling anything for at least a week or two (cooler arrives then) but I can get shots under the car of the piping, more mounting pics etc.

The turbo was rebuilt to run 25psi on a mate's VL Turbo wagon - as such it really comes into ats own over 1 bar. I'm not running anything like that (stock internals for now) but on the VL it would hold 22psi all the way to 7000rpm, and that's using the bleed valve shown in my pics. The reason I now have the turbo is that he cracked his block.

Be careful running 20psi on standard internals, particularly if you're not using programmable management...

if ya get a chance to pull everything off take photo of compressor and exhaust side and try and get the wheels.. if its to much hassell dont worrie about it

how can we stop the boost bleeding off ? is it just the turbo is not efficant or another problem.

also it wont go past 15 psi is their anything we can do to increase it cause it just over spins. eg: (fuel system) or anything else ?

[Guest INASNT]

after all that stuffing around did u actually get more power with the old school vl turbo??

[Revhead]

The car is completely different to drive. The turbo starts to whistle around 1300rpm, usable boost at around 3000, and a real power kick (like a light switch actually, woohoo ) at around 4500. There is absolutely no power drop as the redline approaches. The car makes noticeably more power at 10psi than it did with the old turbo and 13psi.

Absolutely - it hasn't been dyno'd yet (waiting for FMIC and programmable ECU) but it's already a damn sight quicker. Note that the turbo has T4 internals so it wasn't just a case of bolting on a stocker. I wouldn't have bothered if that was the case. It could no doubt might make similar power with much less lag with a different turbo, but for the ludicrously cheap price and DIY factor (and the fact that I'm planning on doing more work to take advantage of the top-end flow of this turbo), I'm more than happy.

The VL turbo is very similar to the stock R33 one in design (water cooled, ball bearing) so I dunno whether it'd be classed as old school.

[Revhead]

Oh, and Cameron - does your brother have the stock BOV? I'm told that they leak over about 10-12psi or so, which might explain the bleeding off of boost.

[cameron]

Oh, and Cameron - does your brother have the stock BOV? I'm told that they leak over about 10-12psi or so, which might explain the bleeding off of boost.

nup his got a (hks ssqv BOV.)

[Revhead]

Got some more pics:

This is the loop in the return line I was talking about.

Another view so you can see where the fitting goes into the block. Note the bracket to mount the other metal hose - putting the bolt in here puts too much stress on the pipework for my liking.

Here's the stock wastegate actuator. Note the clean spot where it was fouling on the intake piping.

Modifying the wastegate actuator using a template. I ended up slightly changing it due to overall length of the bar.

The completed wastegate actuator. I had the further modify the bracket to clear the reshaped bar, but it's all good now

[2fardown]

Looks good RevHead. Sounds like a decent safe upgrade.

[WazR32GTSt]

how would a VL turbo go an on rb20det?

is the exhaust housing the same as an rb25 turbo or slightly bigger? would it bo too laggy?

i'm a big fan of low-cost upgrades...

[Sydneykid]

When I read the post heading I thought WHY WOULD ANYONE BOTHER? :looney:

But then 7 posts later, all was revealed :idea:

Note that the turbo has T4 internals so it wasn't just a case of bolting on a stocker. I wouldn't have bothered if that was the case.  It could no doubt might make similar power with much less lag with a different turbo

So I gotta ask, why didn't you put the T4 internals in the R25 turbo?

[Serious-Seven]

I have been in a few VL's with 250,000klms on the clock.

Still using standard turbo/internals everything stock besides fmic and exhaust system.

was doing low 13's on gtech on 15psi... lots faster then a RB25DET R33... whats wrong with a vl turbo Sydneykid ?

[Sydneykid]

I have been in a few VL's with 250,000klms on the clock.

Still using standard turbo/internals everything stock besides fmic and exhaust system.

was doing low 13's on gtech on 15psi... lots faster then a RB25DET R33... whats wrong with a vl turbo Sydneykid ?

Shoot where would you like me to start?

Shaft diameter

Bearing width

Seal pressure

Wastegate in dump

Wastegate diameter

Oil spray

enough?:headspin:

Don't get me wrong, for a 1986 turbo they were fantastic. But that was nearly 20 years ago and turbo technology (particularly aerodynamics) has moved on, a lot.

[Serious-Seven]

Shoot where would you like me to start?

Shaft diameter

Bearing width

Seal pressure

Wastegate in dump

Wastegate diameter

Oil spray

enough?:headspin:  

Don't get me wrong, for a 1986 turbo they were fantastic.   But that was nearly 20 years ago and turbo technology (particularly aerodynamics) has moved on, a lot.  

I know where your leading but im saying how will a stock r33 turbo outperform a vl turbo in any way ? in actual performance from 0-100 and 0-180kmh tests...

what im thinking is putting one of these turbos in my R32. ( vl) but would it be better to put the R33 S1 turbo in it ?

[Sydneykid]

I know where your leading but im saying how will a stock r33 turbo outperform a vl turbo in any way ? in actual performance from 0-100 and 0-180kmh tests...

what im thinking is putting one of these turbos in my R32. ( vl) but would it be better to put the R33 S1 turbo in it ?

There is far more to a 0-100 time than the turbo, vehicle weight being the most obvious, followed closely by engine capacity. So comparing a VLT with an R33 GTST really is a waste of time. :headbang:

To answer your question, I have an RB20DET with an RB25DET turbo on it and I wouldn't even think of taking it off and puting a VL turbo on. The average power would suffer greatly, plus I would have to change a whole pile of stuff to get it to fit. The big advantage of the RB25 turbo on the RB20 is it fits straight on. Just swap over the wastegate actuators (the RB20 one has a higher spring rate).

[salival]

Is this much of a performance gain? and could you run a little more boost?

[rev210]

I know where your leading but im saying how will a stock r33 turbo outperform a vl turbo in any way ? in actual performance from 0-100 and 0-180kmh tests...

what im thinking is putting one of these turbos in my R32. ( vl) but would it be better to put the R33 S1 turbo in it ?

The R33 gtst beats the VL in factory stock form, based on manufacturers info.

It also beats it when mildly modded and makes more power as well.

Consider the factory turbo'd R33's that have run 12's. My old one ran low 13's with the factory intercooler and ecu. Thats on a 'real' drag strip. You can add at least half a second to that g-tech time to get a better picture of what the VL will really do on a drag strip.

The only thing going for the factory VL turbo is the steel exhaust wheel other than that it flows significantly less horsepower than the Factory R33 turbo. Also the old VL turbo's love to crack the exhaust housing. Try getting 200rwkw out of a stock VL turbo.