Rb20 E85 Conversion

[sneakey pete]

I'd be finding a new tuner if its costing you 1K for a E85 Tune, then 1K for a re-tune with a new turbo and nothing else changed on the engine...

Also it'd be a cheaper exercise to go buy a garrett GTX2863/2867 or something, and track down all the other required fittings/hoses separately, and you'd get a better turbo out of it.

[Missileman]

Yes I was exaggerating a tad, but the point remains, do it right the first time, eventually that 20+ year old ceramic turbo is going to start shedding blades, whether it does it at 7psi or 14 who knows.

The OP seems to be happy to accept that risk, so I will butt out now.

The way the aussie dollar is going that HKS turbo might not be such a bad buy, it tempted me.

[sneakey pete]

you can get yourself the same turbo locally for 1.7K, or the GTX2867 (same flow rate, smaller wheel.. what's not to love?) for about 2K, that leaves 1-1.3K to find lines, a wastegate, piping, studs and gaskets, spend the significant change you'd have on beers.

Or you could buy the HKS kit...

[Missileman]

I was quite happy to accept my 800rpm lag penalty and only pay $900 for a Hiflow, though with some cam gears and a professional tuning it should reduce to about 500rpm. For me it made sense to go hiflow, when you start talking 2-3K for turbos your getting close to the threshold of ditching the 2L and going RB25

Edited August 20, 2015 by Missileman

[sama1500]

Do you have an rb20 highflow or rb25 highflow on yours?

[Missileman]

RB20, but I believe they share the same housings, so after hiflowing they come out the same, but you would be best to talk to Stao from HyperGear to check that. The RB25 Neo is larger though.

Edited August 20, 2015 by Missileman

[GTSBoy]

I don't think the RB20 exhaust housing is a 21U like the R33 RB25. I think it is still a little smaller.

[sama1500]

Yeah I'm fairly sure the rb20 is slightly smaller than the 25, I know the 25 neo ones are bigger still, what's your lag like missileman?

[Dose Pipe Sutututu]

RB20 is smaller than RB25 which is smaller than a RB25 neo.

[sama1500]

I just said that lol, I'm wondering what the lag on the 20 highflow is like, if anyone has a 25 highflow on their 20 would be a great help if you could let me know what its like as well

[Missileman]

its about 1000rpm behind in making positive boost, and about 800rpm behing in reaching 10psi and thats running a safe home tune @ 1 bar (3800rpm), I have improvised knock ears and a wide band. I intend to get cam gears and a professional tune done as soon as I can afford, but fcuk-heads keep running into me and other things need attention to so tune is on hold for a while.

I've tuned it the best I can without a dyno but road tuning is harsh on the auto transmission

[sama1500]

Sounds fairly responsive though, I'd imagine an r33 25 highflow with tuning and e85 should get around the same response you're getting with the 20 highflow so I might opt for that as the 20 highflows are quite rare second-hand

[Roy]

My $6...ie loads of 2c!.... Its a turbo car so turbo selection is kinda important.

Waaaay too many 20 owners choose the wrong turbo imo and the engine ends up getting blamed. Buy a blown HKS 2530 or 2540 to get the T3 GT28 housing in the right A/R for an RB20. You can get them for $100-250 used and then throw a GTX 2863 or 2860 at it.

The 67mm wheel without a proper exhaust manifold IMO won't work well with the 2867

With E85 the one thing RB20s take to VERY well is boost and revs so forget mismatched hi flows meant for an RB25 and spend <2K on the right turbo to give you bloody good punch and top end.

Given the final drive ratio of the R32 and weight you will be no slower than many RB25 powered cars... Even more powerful ones as they tend to just fry tyres with the extra power and torque unless they have sorted susp and tyres.

Please don't go RB25 high flow. You will make a punchy reliable 250-260rwkws with the GTX2863

[sama1500]

So a hks 25xx turbine housing will bolt straight onto a Garrett gt28xx turbo? Is it just a case of taking off one housing to fit another or is anything else required?

[Dose Pipe Sutututu]

HKS2530/5 are ok, but they're starting to show their age in terms of technology.

I would rather a brand new turbo with some form of billet wheel.

[sama1500]

i think thats why roy suggested using the housing off a hks 25 turbo with a garrett gt28 series turbo as they mainly come with housings to suit the sr20 and buying one to suit an rb is like an extra 500

[Missileman]

Sounds fairly responsive though, I'd imagine an r33 25 highflow with tuning and e85 should get around the same response you're getting with the 20 highflow so I might opt for that as the 20 highflows are quite rare second-hand

It's acceptable, you do notice the lack of torque from 2500 to 3500rpm compared to the stock turbo, but after that it leaves the stocker in its wake. The stock turbo tends to run out of breath near 6000, the hiflow hammers all the way to redline.

I don't know how the RB25 turbo behaves on a 20 but it must be somewhere between the two.

If you're trying to get every last bit of response then by all means follow what Roy has suggested, if you want something that bolts up to the stock pluming and is indistinguishable from stock, then look for a blown RB20 turbo on the forums they turn up every few months, that where I got mine, and then send it to Hypergear for hiflowing.

[sama1500]

sounds like two good options! i wish my car came with the stock turbo instead of the rb25 turbo so i would have a better basis for comparison though

[sneakey pete]

The 67mm wheel without a proper exhaust manifold IMO won't work well with the 2867

Fair enough, i'm well out of the rb20 game now.

Mike, I had a stock series 2 R33 turbo on my old R32, from memory it was almost as punchy in the low revs... and fell over almost as soon in the high revs, only made 174rwkw with a tune. May have been an issue with my decision to go for an ARC side-mount instead of a front mount though. Looking back i really wish i'd put in a kit to measure the air temps before/after the cooler, I bet that they were going crazy but I can't be sure.

So a hks 25xx turbine housing will bolt straight onto a Garrett gt28xx turbo? Is it just a case of taking off one housing to fit another or is anything else required?

You'd need to get some machining done to fit the correct profile, about $150 ish depending on who does it. Note i don't think you can do this for a gtx2860, only a gtx2863, i've run into issues trying to get gtx2860's sorted for gtr suitable comp covers. issue is that gtx2860's are smaller than 2530's (and all of the other gtr style ball bearing comp covers), so you can't exactly machine in extra material

[KiwiRS4T]

Fair enough, i'm well out of the rb20 game now.

Mike, I had a stock series 2 R33 turbo on my old R32, from memory it was almost as punchy in the low revs... and fell over almost as soon in the high revs, only made 174rwkw with a tune. May have been an issue with my decision to go for an ARC side-mount instead of a front mount though. Looking back i really wish i'd put in a kit to measure the air temps before/after the cooler, I bet that they were going crazy but I can't be sure.

I doubt it - I made 225AWKW on my 25DET with a GCG highflow and a Trust SMIC (although it went to 245AWKW with an HDi front mount).