Sv Rx7 Turbo On Rb20?

[Shypo]

hi all,

I have tried searching but it comes up with a bilion results & non seem to answer my question..

I am wondering if it is possible to bolt on a Series 4 or 5 Rx7 Turbo onto the stock RB20 manifold?

- Do rx7 turbo's have the same T3 flange?

- Would it be worth it in power terms?

I understand I would have to get water & oil lines made up & also a new dump pipe.. but as the Turbo would be free I believe this would be a small outlay if its going to make some decent power over a Stock RB20 turbo or a SI R33 turbo..

All help would be greatly apreciated.

Daniel

[Adriano]

If its a series 5 itll be really laggy, even a series 4 will be very laggy, they aren't a to3 bolt pattern, and dont have very big compressor side to them, it would be quite a lot of work to make it fit, they are quite a unique turbo which is really only suited to rotaries without a fair amount of internal modification requuiring at least a to4 comp wheel, but by thr time you have done that, the budget isnt so attractive

[Shypo]

So all in all its not worth it?

Probably a better idea to sell the RX7 turbo & put it towards something decent..

Thank you very much for your help..

[discopotato03]

From memory the S4 and S5 turbos were Hitachi HT18-S by name . Neither had a T3 mounting flange and one or the other had a twin entry turbine housing .

Rotors hate backpressure which is why their turbos are large on the exhaust side compared to 4 stroke piston engines . So they are not really suitable for an RB20 though many have used them as the basis of high flow turbos . You could look at their centre section as a T3 copy with a pretty healthy sized turbine . The comp wheel is quite small as is the compressor cover . They are not a total loss but any potential they have may not be cost effective unless alternate compressors and housings are cheap or free .

For an RB20 I'd give it a miss .

Cheers A .

[Fixxxer]

Good advice from all. Rotary turbo's are not a good match for piston engines (as in putting a s5 turbo onto a RB20. It will be laggier and doubt it would flow any more than a r33 turbo at similar boost pressures.

As another example, in terms of T04 turbo's, I think most piston guys would be running something like a .84 A/R turbine. Rotors would use the 1.00 or 1.15 or even 1.32 A/R turbine because of exhaust flow. I have a T04R turbo sitting next to me, I chose the 1.32 exhaust A/R for good top end on my 13BT. If I stuck it on my RB20, I reckon I wouldn't see meaningful boost until about 5000rpm in 3rd gear

Fixxxer

[paulr33]

it would be ace if you had a rotary engine, but you don't

much like a truck turbo would be ace, if you had a truck engine

there would be better suited turbos, the rotary housings are usually large as the flow tons more gas than a humble piston engine

[Fastrotor]

I've done this about 5 years ago when i put a NICS rb20 into my R31 skyline. I had the turbo off my S4 rx-7 rebuilt std, and used that.

I had a flange made out of 12mm steel and welded onto the manifold, then i ported it out to make a smooth transition to the turbo flange.

The power doesnt come on hard till about 4500 rpm, but after that is went very well.

Please note, the S5 turbine housing is actually the smaller AR of the two. It also has the much better wastegate , with its twin flap design.

SO if you were going to try it, use the S5 (if you need to know how to identify them, let me know)

I spent quite abit of time manually messing with the R31's computer and i got the timing and fuel pretty decent on it . I sold the car off and after 5-6 owners and flogging, it was removed and is now in a Bluebird wagon , of all things. New owner whacked on an aftermarjet ECU and tuned it with somemore boost and its run a low 12 sec ET ..... Still all stock internal etc .. food for thought.

I guess if you had one already in good nic, it could save you some dosh, but as the other guys have stated, there are alot better suited turbos out there that just bolt on.

Gary

Edited November 1, 2006 by Fastrotor

[Cplus]

Please note, the S5 turbine housing is actually the smaller AR of the two. It also has the much better wastegate , with its twin flap design.

SO if you were going to try it, use the S5 (if you need to know how to identify them, let me know)

actually, TMK the S5 had the bigger A/R. I've looked at quite a few and the S4's are 0.88 (equivalent*) and the S5 1.00 - it is def. the one with the tricky dicky twin flap wastegate arrangement however. the S4 has a piss tiny flap that is very prone to creep.

back end of the S5

they can be high flowed easily with T04 wheels and comp covers.

my mate ran a flat 12 in his 4.0l cortina, had;

Garrett H3 60mm compressor wheel

TO4 .6 comp cover

360 degree thrust bearing

Sierra GroupA turbine

full boost by 2000rpm - but on 4.0l - ie: not so good on a 2.ol

C+

*they were twin scroll (rubbish) with a 0.4 primary and 1.0 secondary

[discopotato03]

Yep plenty used them as a Hi Flow basis , mine had an 8 bladed TO4B -24 compressor which was a bad move . I was not clued up in those days to the fact that the 8 blade wheels were intended to be used with larger TO4 turbines and were low speed wheels . The 6 bladed B series wheels worked much better because they don't try to pump as much air at low wheel speeds where the turbine is not really developing enough shaft torque to be responsive . Also the extra air from the 8 blade wheel tends to make the turbo surge prone when it does come on boost .

I think I still have mine buried in the cave so I'll try to get some pics of it in a couple of days time . It had a VG30 turbine housing and RB25 style compressor cover at first then an RB25 turbine housing because it was very laggy . The RB 25 housing brought it on earlier but made the thing surge as well . Too much air too early .

As always its a but dubious using bored out non native turbine housings and I'd say the original Hitachi's were probably the only ones designed for it . Anyway that turbine being reasonably large (and heavy) won't be real good for a 2L six and the high oil shear drag from the bush/plate bearing system just makes it worse . I won't say it couldn't work on an RB25 or 30 its just not an optimal basis to begin with . Often you find with any used bush bearing turbo shaft and or housing bore wear and rear piston ring seal groove wear . They may be cheap or even free but the costs mount up down the track . In some ways you can see why companys like Garrett prefer to sell a complete cartridge rather than bits for rebuild . You get factory tolerances and brand new bits and refitting the housings is easy and quick - lower labour costs if your paying for it .

Do your sums very carefully because if you start playing with things like this you can often end up paying more money for less performance/satisfaction/dinosaur technology . If I was trying to do it on the cheap I'd stay with factory type turbos or at least a combination of factory bits . I always thought the RB25 turbine housing on the R32 turbo would be a cheap easy upgrade but thats only a guess .

Cheers A .

[salad]

I always thought the RB25 turbine housing on the R32 turbo would be a cheap easy upgrade but thats only a guess .

arent the rb20 and rb25 turbine housings the same? or do you mean compressor?

[Ceffy_SA]

http://i3.photobucket.com/albums/y65/Ceffy_SA/DSC00096.jpg

http://i3.photobucket.com/albums/y65/Ceffy_SA/DSC00097.jpg

I currently have a Rx7 turbo installed on My RB20DET Silver top Cefiro, its basically a Rx7 HT-18S turbo of a S4 Rx7 but it has had a RB20 turbo rear exaust housing fitted to the turbo and the large steel wheel from the Rx7 turbo has been kept with the Rb20 turbo exh housing "machined" to fit.

Overall the compressor is not much bigger than the STD RB20 turbo (from memory it was only 4mm bigger on the exducer side) but ther is not much lag at all, really, currently full boost (around 14psi) is available at around 2800rpm, "Spool up" time is increased a little but its not huge by any means. I havent had it dynoed properly yet or tuned yet for the new turbo but the car does seem alot quicker with the new turbo on, boost no longer tapers off in the top RPM range and i can run over 15psi without worrying about the stock ceramic turbine shooting off. The turbo only cost me $500 and only required a custom oil line to be made up for it (going from ball bearing to plain bearing)

[Shypo]

Thank You very Much all who have posted. EXTREMELY helpful!! Think I'll go for something a tad easier..

[discopotato03]

Yes Ceffy thats exactly what mine looked like from the back only with the slightly larger RB25 type turbine housing .

All RB25 turbos had larger comp covers than RB20 types which is not surprising because all the air goes through it and RB25's are 25% larger than RB20's .

[Ceffy_SA]

Discopotato do you think i would be better off fitting a RB25 exh housing to my current configuration and also going with a better compressor? Also out of interest have you seen any power figures with this type of turbo on a RB20? Thanks

[discopotato03]

I'd be getting it tuned before anything else so you have a base line to work from , does it run a PFC or other tunable computer ?

Cheers A .

[Ceffy_SA]

Has a Dr Drift re-tuned ECU at the moment, had the ECu re tuned recently after the turbo was put on but my time was cut short on the dyno because of worn out GTR fuel pump and then Misfiring plugs, its now all sorted but i havent had the chance to get the re-map finished. I was kinda hoping to get close to the 200RWKW mark with the new turbo or al least see an improvement over my original 165RWKW with the stock turbo on. 200RWKW with new Rx7 turbo wishfull thinking perhaps?

[discopotato03]

In the days of green potatoes we had this frankeinstein built , HT18S turbine in T3 wet core with TO4B -24 compressor in an RB25 comp housing . Don't copy this one because its a surging unit with very average performance .

Both the RB25 comp and turbine housings had the number 2 inside them , in the inlet on the turbine housing and the outlet of the comp housing .

[discopotato03]

And the RB20 turbo that replaced it .

[discopotato03]

And finally the GT2860RS that worked so well on my FJ20ET .

[T04GTR]

series 4. series 5 is split pulse and diferant a/r,s i think