Staged Turbos

[SECURITY]

after i get my car running ill be starting an rb30/26 project.

on that motor i want to run a pretty large turbo (havent decided which yet), and i was thinking of a staged turbo setup with something smaller to build up exhaust flow and give me some low-mid power before the larger one spools, which in turn will make it start spooling earlier.

im no mechanical genius so im coming to you guys for some guidence on how i could make this work as im not the type of guy who would walk into a workshop and say "i want this, that, those" and flop $30k on the table. most of the work will be done by myself so its important that i understand how it all works.

the motor is going to be used for drags. i know i could use nitrus but i'd rather something different.

i'd appreciate your thoughts on running this kind of setup too.

thanks guys.

[Tommyk]

Forget about the staged setup.

If its going to be a drag motor, why would you need a staged turbo setup anyway. Look at what Brett (buster) has done with his rb26/30 setup and try to copy it

[SECURITY]

i want to try something different. i want the pro's and cons of a staged setup before i make a final decision.

[discopotato03]

I would forget staged turbochargers as well . One thing they do garantee is high exhaust manifold pressure at low/med revs because of the primary turbos small turbine and housing . Also the changeover from primary to secondary is difficult to achieve smoothly . What is supposed to happen is the larger secondary turbine gets a small but increasing amount of exhaust flow to spin it up to useful speed . Its nearly impossible to do this without robbing the primary turbine of enough energy to slow it and the engines torque development . The secondary compressor has to attempt to come on line and provide enough volume and pressure to take up the supercharging effort smoothly . It quite complex with the secondary compressor having air valves to prevent air from the primary compressor backfeeding to atmosphere through its air inlet . Far more trouble than its worth and very expensive to develop and manufacture .

Subaru tried it with the B4 and ended up prefering the larger EJ25 with its twin scroll or split pulsed single turbo . One of the late Mazda Rotaries (was it ser 5 or 6 ?) used it but it ended up being so complex and unreliable that no one wanted to know about it when it acted up . In fact one of the rev head magazines had an article about how to convert them back to a Hybrid Hitachi HT-18S / TO4B single turbo .

I think the most successful solution is to have as many cubic inches as is economic to build and if necessary turbocharge that . The RB30 should make enough torque off boost to make a Skyline feel pretty good (provided final drive gearing is not too short) and spool the sort of turbos that make BIG power if everything else is made to support it .

Cheers A .

[SECURITY]

great info there discopotato. ill probably go with your suggestion and try build up some cubes.

is there an rb30 stroker kit?

[R31Nismoid]

heheh.. you cant stroke the RB30... you can get 3.1 with over size pistons.

[Tommyk]

There is a 3 litre stroker kit, but that involves lots of money (os giken)

Your best and cheapest bet is to go an rb30 bottom end with a 25 or 26 head.

If you want something that revs a bit better, get an rb26 block and get a stroker kit for that (tomei or hks 2.8) However, that will still cost you a fair whack of dollars

[wrxhoon]

Just buy a VL rb30 bottom end , give it a light hone, some used pistons and rings and bolt a RB26 cil head on to it all up $2000 . Get a big high mount turbo, rev it to 10,000 rpm and you will have a very quick R33 gst , should last for a couple hundred k's no problem.

[Tommyk]

Jerry but rev a stock head and bottom end 26 and it wont last very long at 10000 rpm either.

I doubt the rb30 would last a few hundred kms at 10000 rpm. One go and I assume it would be a big bang. And that would be on the dyno while tuning it

[wrxhoon]

Jerry but rev a stock head and bottom end 26 and it wont last very long at 10000 rpm either.

I doubt the rb30 would last a few hundred kms at 10000 rpm. One go and I assume it would be a big bang. And that would be on the dyno while tuning it

Who said anything about tuning Tom?

[rob82]

Who said anything about tuning Tom?

Why only spin it to 10000rpm I'm sure the VL bottom end could see 15000 rpm!!!! Tuning is for girls any way!!!

[StockyMcStock]

pffft - just rev it straight through that little harmonic that they get at 7500. if you pass through it quickly enough, your crank will be fine i reckon!

[R31Nismoid]

There is a 3 litre stroker kit, but that involves lots of money (os giken)

no but thts not in a 3ltr bottom end to begind with.

thats a 2.6 if im not mistaken

[Warpspeed]

Forget about staged turbos, if the manufacturers cannot get it to work properly with all their resources, you or I have less than zero chance of making it work either.

But staging a turbo and a supercharger has been proven to work very well. Nissan did it on a production engine, Audi did it on a production engine, and now the 2006 model VW Golf GTI in Europe has both a turbo and a supercharger fitted to it.

I have done it successfully too, and Stocky is in the final stages of building a turbo + supercharger system on an RB30DE. So stay tuned...

[Tommyk]

Correct. it uses a spacer to get the capacity of 2998cc

[SECURITY]

when i said building a rb30/26, i meant im going to completely rebuild it... i.e. rods, pistons, cams etc.

im just looking for some kind of setup i can use to take advantage of the motor as much as i can.

[Tommyk]

So how much are you looking at spending all up ?

That will determine the quality of the build and components

[SECURITY]

whatever it costs to have an unbreakable motor... im willing to spend around the 25-30k mark including the turbo.

it wont be a straight up 2 week build.. ill be building it over time as its autumn and my money tree is losing all its leaves

[wrxhoon]

If you are serious about building a strong engine then buy a decent block too . Nismo GT is a good start .

[Tommyk]

Jerry

but the rb30 is unbreakable. I have heard it is good for over 1000ps !