R33 Rb30 Conversion

[Steve]

Thats a really interesting point lowlux - I was just reading tonight in a book called '21st century performance' where they were comparing variable cam timing and different cam profiles - and guess what - with larger profile cams the vvt made no gain at all, this was on a lexus v8 I think - the book is at work so I cant look it up at the moment. Cant remeber the cam profiles either - sorry.

Has anybody experimented with aftermarket cams and VVT?

[lowlux]

all ive found out is that ppl that go aftermarket cams/larger cams get rid of the vvt and get Adjustable cam gears to tune them better. Bigger cams for me isnt a option its going to get done as its for free soo yeah

[Cubes]

Apparently the R32 GTR's had a problem where the oil pumps drive gear would crack in the corner of the flats.

The R33's oil pump drive is longer on the r33/r34 crank to rectify it. Apparently..

[25t]

Hi All

after alot of ISSUES the rb30 twin cam turbo is alive.seems to be a problem with the VVt as about 5000rpm it stuters and coughs

due to $$$$cost the standard turbo,injectors and ecu have had to make do for the time being.

the rb30 block is also standard NA internals ,all seems well

can anyone suggest a safe boost pressure to run it at?

thanks to this topic/post it has been possible for me to do this conversion ,much appreciation goes out to all who added to it.

now to find a dyno and get a checkup.

cheers

[Cubes]

Well you should be running a cr of around 8.3:1. So boost isn't a problem but the ceramic exhaust wheel is.

Due to the extra capacity the turbo now has to spin faster more rpm to keep the same boost pressure as when it was 500cc less.

SO running 1 bar would be like maybe running 16-17psi on a Rb25det.

So be carefull with the ceramic exhaust wheel.. Maybe run 12psi through it max just to be safe.

So how does the off boost torque feel compared to the RB25?

Post us some pics

[DennisRB30]

25t, just to re-cap. You have a R33 with a VVT RB25DET, you changed the bottom end to a stock RB30 without changing any other support systems... Correct?

How does it run, other than the stutter? Does boost come on much faster? Does it feel a lot more torquey?

You could adjust the base timeing for more advance becuase the CR has droped a fair bit, and like joel said, you could run a heap more boost becuse of the lower CR, but the turbo will not like it at all.

[Steve]

Congrats 25t - time for a beer or 20:)

[Sydneykid]

HI Guys, I have seen a number of mentions of the VVT change over point being at 5,000 rpm. If your ECU has an adjustable change over point then this is the way we do it.

We run the car up on the dyno with the VVT locked in the "low rpm" position and save the power graph. We then lock VVT in "high rpm" position and also save the power graph. We then overlay the 2 graphs. Where the 2 power curves cross over is the most efficient position for the VVT change over point to be. So we set the ECU to change over at that rpm.

Hope that helps.

[GiJOr33]

What about getting Adjustable Cam Gears instead? Is that a better option? or just an easier option?

Cheers,

Andrew

[25t]

Hi all

as suggested i have advanced the timeing to 20deg, made a huge diffrence ,no stuters anymore

just to confirm ,this motor was built with the lowest cost in mind

all 25t parts that could be used were, oil pump,water pump,oil cooler etc

VVt has been retained with the use of a oil hose from the rb30 oil pressure sender port which was plummed into the vvt feed gallery as per a link Joel posted a few pages back.

the rb30 block was given rings and bearings(not needed) as it was the correct thing to do while it was in bits.the RB30 only cost $200 complete

I tried to install the rb25 piston squirtersinto the rb30 block(disaster) the oil gallery casting is too thin and when installed the squiters restricted oil flow to the mains and bigends,a post from Sydney kid stated that the squirters were not necessary so i capped the holes.

the motor feels stronger/torquey across the rev range and running 6psi boost feels like the 25t did with 12psi.

the only other issue worthy of noteing is the bonnet only just closes ,sadley the strut brace has had to be left off. I guess there is always some tradeoffs

cheers

[Sydneykid]

That's a great job 25t, someone brave enough to do a straight, low budget swap of components. I am looking forward to seeing some dyno numbers.

Hi GiJOr33, the VVT changes the timing of the inlet camshaft under instructions from the ECU. So you can have advanced timing for more power at high rpm and retarded timing for more power at low rpm. An adjustable pulley gives one or the other, not both. I would not worry about adding VVT if it was not already there, but if it is why not use it?

Hope that helps

[DennisRB30]

25t, so was it worth the effort and money? How much did it all add up to? A list of what was done vs cost would be great. Do you have any 400m times or dyno charts from before the conversion, a before and after comparison would be good. Does it still rev strongly to 7000rpm?

Have you driven it enough to notice the fuel consumption?

[25t]

Hi Dennis/all

ive never been down a drag strip ,so i dont know a time,at the moment with the boost set low 6psi its as quick as the 25t was with the boost up at 12psi.

its not been driven very hard yet as its only done 250ks

comsumption seems to be about the same as the original rb25 ,im guessing but the ECU still thinks its 2.5ltrs so the fueling etc is as if it was 2.5ltr ,as soon as the boost is on they run rich anyway?

Sydney kid ,when i get to a Dyno what are the basic things i should be getting checked/changed?

costs =

rb30 motor $200

rings/bearings $200

gaskets/lipseals $100

acid bath,gallery brush,frost plugs$50

oil hose/fittings for VVT $100

cheers

[DennisRB30]

That is cheap. What head gasket did you use, RB30E, RB30ET, RB25DET? You done all the work yourself didn't you?

[lowlux]

remember thats n/z prices dennis, the piston and rings over here will cost u $320 for non turbo pistons, but $350-380 for better chromeoly rings actually the prices are probably more than that cause there my prices from work

[DennisRB30]

Ahh I didn't see 25t was a from NZ

[GiJOr33]

25t ... have you got a pic of the VVT fittings? i had a look back through the thread (and a long thread at that) and didn't see it. I'm keen to see how you've set it up. I've been having a chat with Sydneykid about it and he reckons that you can just ditch the VVT and get an adjustable cam gear for the exhaust side. But i like to see what others have experienced too. I've got forged pistons and stronger rods, with a big turbo... so it will probably be more beneficial to change the cam timing rather than keep the VVT.

[DennisRB30]

You cant keep the 25 rods and pistons when you change to the 30 block can you? I thought that would result in a megga low CR.

[sLo-32]

Congrats 25t. It'll be nice to see some figures as im looking to do a budget conversion aswell....not too budget but that all depends on how much i sell the calais for

You were saying that the bonnet just closed, how would this conversion go with a R32 then? Are the engine bays different size?

[DennisRB30]

When I mentioned bonnect clearance earlier in the thread i was told there was no issue. I thought it would be cutting close.