Map Tracer Query

[benl1981]

Cubes..

"The holding a steady throttle, boost builds and then starts surging 'while' holding that same throttle opening"

That is the problem that I find difficult to live with. Motorways etc when doing 100km/h in 4th or 5th. This is definately a problem when holding a steady throttle and boost just coming on whilst maintaining same throttle input..

ANd when I say flicking between load cells...its more like 3 or 4 cells.

The AFM voltage I can see flicking between 2200 mv and 2700mv, you can feel a slight roughness but this oscillation is usually followed up by a large jerk and you can see the AFM voltage jump straight down the vertical when this occurs.

[Cubes]

Its all good. I did skim read a touch and for one reason or another didn't see the 3-4load point drop but read it as flicked between load point 3-4.

Yes a larger turbine housing will sort the surge.

Improve the motors ability to breathe will also; You have cams and cam gears yet?

A turbine housing might set you back 50-100 + 300 for machining. Might be better off put towards a set of cams or reground rb26 cams? BUT its still not certian the surge will be sorted.

Reground rb26 cams are a shade over $200 for 2 sticks. You net around 8.5mm lift and ~252-254duration. So a nice mild increase that won't completely kill your low end.

[benl1981]

Thanks Cubes. No I don't have cam gears or others. I am in negotiation with GCG so I may be able to sort something out with them because the turbo was sold as a standard Rb25 so should suit the car the way it is.

New cams are a big deal..take timing belt off, rocker cover etc. Not really up for that.

[benl1981]

Anybody know if this looks like BB turbo? Do the non BB turbos still have exhaust housings that are useable?

[Cubes]

The exhaust housing looks suitable.

[benl1981]

Thanks Cubes. Can you tell if it is BB or bush from that photo?

[Cubes]

Your after the OP6 turbine housing.

I can't see by that pic if it is an OP6 or not.

The compressor backing plate actually looks the same as an early (series 1) RB20DET BB turbo I've seen.

Its definitely not the run of the mill Leopard/Cima Vg30DET turbo; it 'could' be a really really early turbo from one of those. Not sure.

The only VG30DET turbo I've seen is that from the Z31 which is journal bearing and then that of the later leopard/cima. The R34 GTT RB25DET Turbo also runs the same OP6 turbine housing that the VG30DET turbo does.

Can't be sure exactly what that turbo is without seeing more pics.

[benl1981]

It has 45V1 on the comp housing. How can you check it is the op6 housing besides taking it off? Is it always on the inside side?

So the journal bearing housing works also?

[Cubes]

The OP6 is stamped on the outside of the turbine housing near the core.

So thats a journal bearing turbo?

Would be interesting to know what car that is off as they are an extremely extremely rare turbo if thats the case.

The Z31 VG30DET's as I said above run a VLT style turbo where as the Leopard/Cima VG30DET runs a the BB OP6 Turbo with 45v1/2/3/4 on the comp cover. It 'could' be the really early 1980-1986 Leopards; I'd assume they would have run around with the journal bearing turbo's. But whats interesting is why would they not have used the same old VLT/Z31 turbo.

http://cgi.ebay.com/ebaymotors/VG30DET-TWI...1QQcmdZViewItem

Thats a Vg30DET BB turbo with its OP6 Turbine housing.

[benl1981]

I'm not sure if it's journal bearing or not. SO you cant really tell if its 0p6 without taking the housing off?

Cheers

[Cubes]

You can.. Its on the outside of the housing near the center. From memory its also on the opposite side near the dump flange.

While its off port match the t3 flange.

[Hardman69]

Ha HAA ! I am sworn to secrecy on my Hi-Flow, suffice to say it'll do about 270rwkw, and has a watercooled plain-bearing core. It's not excessively laggy with the AVC-R tweaked-up correctly - certainly does the job for me, anyway!

Maybe You should investigate how changing the compressor housing slightly would affect surge? This seems to be at the heart of the problem, after all. Half a mil' here, a few thou' there.. . . might make all the difference.

[benl1981]

Cubes, have all the ones you seen had OP6 in that location. This one has Y24B..

might not be right.

Hardman - sounds like you got a good turbo there. The secret recipe Yeah I think the compressor is where it's at but the exhaust housing may be the cheapest to change..

[Cubes]

All of the larger turbine nissan turbo's I've seen have the OP6 on them.

You can't get any more pics? Get one of directly looking at the comp wheel also showing the compressor cover and one of the turbine housing in a similiar position. Then we can see both wheels and know or at least have a better idea of what it is.

Its definitely not a run of the mill VG30DET turbo; I suspect its something old. I suspect that due to the comp covers backing plate. Either that or its been highflowed.

If you have the turbo take some measurements of the turbine scroll at points that are easy to describe and I will compare them with the one I pulled off mine a little while back.

From memory the cross section width near the wastegate flap is ~5mm wider with the OP6 housing compared to that of the rb20/rb25 housings.

[benl1981]

Well it has 45v1 on the comp cover and looks like the vg30 actuator - (not flat on the top)..

Not sure now. Might let it go..

[benl1981]

cubes - did you think it looked like the bigger housing originally?

Do you have any measurements I can check?

Thanks

[Cubes]

I actually think that looks bigger than the leopard/cima vg30det turbine housing. :S

Down towards the bottom of the scroll where it tightens up.

I'll throw some pics up of mine.

[benl1981]

Is there any measurements I could take to ensure I am getting the right one?

bigger than the standard VG30?!! Wow..

Thanks

[Cubes]

ok here's a pic.

You can see where the scroll tightens up. The Vg30 looks tighter.

What does it say inside the Turbine Inlet? Is there a stamp with a number inside?

I'll take some measurements.

[mr_rbman]

Anybody know if this looks like BB turbo? Do the non BB turbos still have exhaust housings that are useable?

thats a non ball bearing turbo, u can tell by the ribbing on the back of the front housing. To me it looks like a t3 off a VL Turbo!

Edited July 2, 2007 by mr_rbman