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The mkiv Supra Owners Club

Engine Uprade Spec?


rob wild

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Hi Guys into the next stage of my performance upgrades and I’m doing the specification for my engine. As a base specification what do you think? Advice etc

 

Wiseco 86.5mm/8.5:1 piston&ring kit, sides are teflon coated.

Crower Connecting Rods

HKS 1.6mm headgasket

ARP headstuds

ARP mainstuds

New OEM Crank pulley

Upper & Lower gasket set is

Rod bearings

Main bearings

HKS cams

HKS cam gears

HKS timing belt

Crower Valve Spring & retainer set

OEM Valve seals, Valve locks, Spring seat locators

OEM Crank seals

Re-ground crank

 

Cheers Rob :)

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I asked this recently... seemed to be a big outlay for little gain:)

 

Ah okay, was just curious, I did it on an a-series morris minor 1098cc engine, used a mg metro turbo head which flows better anyway because of the larger valves. It certainly sounded better and had a lot more go (for a morris)... until it bent a push rod due to the valve assembly being twin sprung.

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Personally I'd get as near to stock sized pistons as possible (86mm) to preserve the integrity of the block. If your block isn't damaged it will likely just need honed to allow proper seal of the new rings, this way you can use 86mm. If the bores are imperfect and you need a rebore, I'd order some custom spec forged pistons from JE in 86.25mm size. You can get custom spec JE's in your own choice of compression ratio and my preference would be 8:1 to allow more boost on our road fuel without the need for more ignition retard. This way, you don't need a super thick fancy make MHG and can use a Toyota 1mm or 1.2mm (depending on whether the head is skimmed much) which is more than man enough for the job (they are also metal) and will preserve the squish area of the head.

 

I'd also recommend new oil and water pumps during a rebuild, belts and tensioners too.

 

Cheers,

 

Brian.

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The compression ratio depends on your aims. I'd rather have 8.5:1 and less timing on silly boost, as that's much more streetable.

 

Custom grind pistons sound expensive ;) If the block is good you should just get the 86mm ones and a hone though, don't overbore for the sake of it, unless you simply must have that extra

 

-Ian

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So the list stands now as:

 

Wiseco 86.5mm/8.5:1 piston&ring kit, sides are teflon coated.

Crower Connecting Rods

HKS 1.6mm headgasket

ARP headstuds

ARP mainstuds

New OEM Crank pulley

Upper & Lower gasket set is

Rod bearings

Main bearings

HKS cams

HKS cam gears

HKS timing belt

Crower Valve Spring & retainer set

OEM Valve seals, Valve locks, Spring seat locators

OEM Crank seals

Re-ground crank

OEM oil

OEM water pump

 

I'm having my head reworked which will include skimming, porting and flowing so i was adviced to go for the thicker head gasket to keep the compression ratio down. This is not fixed in stone as the engine will need to be striped first then i can get the measurements for bearings and have a look at the bores.

 

The teflon coat pistons are much better at handling heat and higher temps etc. Again this is something i've been advised on.

 

Cheers for the advice :)

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Rob,

 

I would go with the 5 stud cam gears if your wanting to run any big numbers mate! (Titan, etc!) I also use custom JE pistons in my skyline and they are very "slappy" when cold compared to the CP jobbies but never the less an excellent piston and very tough!

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We've used JE customs in 2 builds, one had no piston slap noise and the other a bit when cold. It's all down to the piston to bore clearances you run and appropriate ring size / filing. Be very specific with whatever machine shop is bore'ing / honeing your block and run as small a clearance as you can get away with according to the piston spec sheet supplied if you want to minimise piston slap.

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If money was not an issue i would choose CP pistons, then JE from what is available. Hhmm had cosworth pistons in my skyline and do not rate them at all, so changed them for JE pistons. I had the choice of pistons in my skyline drag engine and went for some tomei pistons as recommended by Ron at RK tuning.

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