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The mkiv Supra Owners Club

Any interest in me documenting this engine build?


Chris Wilson
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I have virtually got all my bits together for my Skyline engine build, and I am wondering if people here are interested in my ocumenting its build? Not a Supra I know, but a similarish unit, and i9t may be of use to see its build up.

 

Spec is new Nismo N1 closed deck block, steel crank, steel rods, forged pistons, new head casting, which will be ported, 280 degree high lift cams, decent valve springs with shortened buckets to accomodate the lift, big single IHI turbo with remote wastegate, bigger injectors, Bosch 044 pump and Motec management. It's going in my R33 GTS-t (rear wheel drive and a lot lighter than a Supra :-)) Shell is being cnverted from auto to manual, as it's a mint 7000 miler. Original lightly modded RB25 engine gave 500 BHP on pump fuel, aiming for 650 from this one, with good track day reliability and the potential for 800 with bigger turbo. I want a good low end torque delivery initially, so using a conservative turbo sizing.

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Not sure the weight, probably a bit less than a Supra, block wise. I will weigh the main components before they go together though. Crank is a bit heavier than stock as it's now fully counterbalanced, instead of half balanced. It's nice working on all new stuff, the heads are a bit iffy bought secondhand, as they can crack if they are overheated. Seemed safest to buy new if I am going to be doing a lot of work on one.

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:nana:

 

Yes please!

 

800bhp, RWD, could be a handful. You gonna take it to Ten of the Best 4...? :D Going for a cast manifold or tubular? The one pump is man enough then? Or is that the main pump and you've got a swirl pot?

 

I like "conservative" turbo sizing = 650bhp. And I guess the 280 cams are pretty mild in your book. It's a different world :)

 

-Ian

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nice one love to see new projects going on. see how the master does it :)

 

would be good to hear why you chose certain parts too.

 

good luck

 

Well, I chose the (expensive, very expensive...) pistons because Tomei are seemingly the only maker who do an oil channel cooled piston crown in a forged piston. This alows for a huge amount of heat transfer to be taken away from the ring pack, and should help stave off detonation on our crap fuel for much longer. The stock cast pistons have an oil cooled gallery within the piston crown, too, it's this reason people seem to get away with huge boost without det. However, being cast they are inherently weaker, but quieter, than a forged unit. Silence isn't high on my priority list, so I went for the Tomei ones. Tomei make some great stuff, their cam profiles, for example, seem copies of Cosworth ones. And Cosworth have developed some demon turbo profiles over the years. I wanted a good deal of lift and modest duration for drivability with a smallish turbo, so I am hoping my choice pans out OK, cam wise.

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  • 1 month later...

OK, took the brand new N1 race block to be bored and crank housings checked for straightness and align boring if required this morning. I took the chance to take some pics. There's the new bare head casting, new N1 block, new billet steel fully counterbalanced crank, Carillo type H section billet con rods, Kauffman titanium valve springs, lighweight cam followers, chrome moly steel head studs, Tomei high volume externally adjustable race oil pump, Tomei forged race type pistons with oil shaker galleries under the crowns, longer cam cap studs, a pair of Tomei race Pro-Cams, and some bigger injectors to start with. Once the block's back from machining and the rotatng and reciprocating assemblies are balanced I'll start the short motor build and take pics as I go along.

 

Head will be going for a port and manifold matching soon, then I can CC the chambers and set the compression ratio to suit with a stock thickness MLS head gasket, to maintain squish.

 

Pics uploading slowly over my archaic connection:

HERE

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Some nice kit you got there. Who do you use for the machining/balancing?

It's certainly going to be a beastie when it's built up. Must admit, I'm becoming tempted by the darkside myself (VSpec)...

 

Nice sig BTW - "As car engineering becomes more foolproof the fools just up the ante" - LOL!

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Next bit of interesting stuff. Stock 3 pairs of throttle bodies milled out (tricky job) to take Weber 50 mm throttle plates from side draught carbs (50 DCOE's). These will flow a LOT more air than the stock ones, which are about 45 mm, an example of which is on the right of the pic of the modified bodies. I have had Cometic make up some custom metal gaskets for these.

 

I now have a wastegate too. Secondhand, but the diagphram is good and no casting cracks, so in perfect running order.

 

I also fabricated some adjustable bottom suspension arms by hacksawing off the stock ends with (spit) rubber bushes, and welding on a bulkhead, which I drilled and tapped for 5/8 inch male UNF stainless NMB rod ends. I turned up some spacers from Dural to recreate the same width as the stock bushes, so the will just bolt up to the front crossmember like the stock arms. Excuse the rancid bolt, it's just for stopping me losing the spacers, temporarily! I can now adjust front camber to my needs quite easily, and I have also removed all compliance. Not good for noise vibration and harshness, excellent for geometry control and driver feedback. I will convert the castor arms to adjustable, none compliant tomorrow, again using rod ends and spacers. The stock castor arms have big squidgy slicone filled bushes in the chassis end. No good at all... ;)

 

Pics at http://gatesgarth.com/next/next.html

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