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1998 Bt1 Sedan 26/30 Build V2

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Fukushima Rookie

Fukushima

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Something went wrong with v1 of my 1998 r34 BT1 sedan so I've pulled it to sort it out

IRd5E3E.jpg

Specs were:

RB30 block and crank (with collar, ARP main studs, oil restrictor etc but no drain drilling)

Reimax pump gears, n1 spring in standard rb26 pump

N1 water pump

ATI balancer "1000hp"

Spool rods

Ross pistons

ARP2000 RB26 head studs* (see note below)

tomei 1mm head gasket

R32 RB26 head

HKS 272 poncams

HKS cam gears

GT35R, 6boob, turbosmart 50mm wastegate

ID2000 injectors, single walbro 460 in the tank was dedicated e85

Vipec v44 plug in with MAC boost control

After a couple of hiccups with the build it was all slapped together before Race Wars in 2015 (literally tuned 2 nights before), made ~580hp (430kW) and 700 odd nm on e85 at 21psi

Ran it very hard for a year had various issues

Fried twin plate (upgraded to OS triple)

Boost leaks

Oil pressure dropped to less than 1 bar under heavy braking

Oil leaks (took the spool sump off an put a 25 sump on)

Then the big one - decided to put a bigger turbo on and redo all the piping so I sold the GT35 and front mount off as a kit. Found oil in the coolant so the motor is sitting in a mates workshop at the moment - we will pull it apart and investigate. I suspect using the RB26 studs has caused further issues. The reason it got slapped together in such a hurry was that when the head was put on it the studs stripped the tapped threads out of the block and it all had to come apart for special thread inserts that were meant to hold.

Very rough plan from here is to get the head stripped and inspected. If that's all OK it will get rebuilt with new valve guides and shims and I'm considering lower duration but higher lift cams and double springs.

I have a spare "virgin" 86mm bore block so I will probably transfer the rotating assembly over with new rings and bearings and use RB25 studs.

In terms of oil control this time I will drill out the oil returns in the block, have the head "drain/vent" drain back to the sump instead of a y-piece with the turbo drain and I'll probably put an accusump in the boot.

Then I need to purchase and install a turbo kit and upgrade the fuel system and hopefully the vipec can do flex fuel.

Aim is to go 800hp/600kw at the rear wheels on ethanol, keep it rego'd so I can drive it to work and pick up my son from daycare one day a week, be able to track it at collie (lots of left hand bends), and be able to drop 4th every now and then (only got to do it a few times last year).

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https://www.sau.com.au/forums/topic/464637-1998-bt1-sedan-2630-build-v2/
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iruvyouskyrine Grand Master

iruvyouskyrine

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In terms of oil control this time I will drill out the oil returns in the block, have the head "drain/vent" drain back to the sump instead of a y-piece with the turbo drain and I'll probably put an accusump in the boot.

Have a read of this http://www.sau.com.au/forums/topic/110680-oil-control-in-rbs-for-circuit-drag-or-drift/?p=7226723

Fukushima Rookie

Fukushima

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That's a great summary! I'll be sure to use it as a checklist.

I had a similar catch can setup to simon-r32 including the oil drain to sump I just hadn't plumbed up the vent from the sump to the top of the can.

I also had a gated spool sump which leaked and the extra sump capacity didn't seem to make a difference. My preference this time is to use my modified 25 sump and accusump.

whatsisname Grand Master

whatsisname

Posted
Posted

It is a bit hard to see it but there's a black alloy protective shield to stop road debris from getting flicked up and hitting it or rubber sticking to it. I used the 20-25psi valve - I think, might need to double check that!

  • 2 weeks later...
GTRPSI Mentor

GTRPSI

Posted
Posted

What thread inserts were used to fix the stripped threads?

Have you tested the engine with them in or you have not put it back together again?

Reason i ask is because the RB30 block is already pretty weak in the deck area before going to the larger RB26 studs, adding thread inserts would only weaken it further.

Curious to know which inserts were used and how it goes with them.....

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Fukushima Rookie

Fukushima

Posted
  • Author
Posted

What thread inserts were used to fix the stripped threads?

Have you tested the engine with them in or you have not put it back together again?

Reason i ask is because the RB30 block is already pretty weak in the deck area before going to the larger RB26 studs, adding thread inserts would only weaken it further.

Curious to know which inserts were used and how it goes with them.....

Sorry if it wasn't clear but the thread inserts were done with v1 and it doesn't appear to have done all that well. Give me a couple of weeks and I'll see if I can produce photo results.

V2 will be going back to rb25 studs in "fresh" block

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