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The mkiv Supra Owners Club

What would I need to strengthen the bottom end...?


add heywood
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So, like most on here, every year I spend stupid amounts of money on my car to take it (in my eyes) to the next level... From increasing power, to bodykits, to arches etc. If I decide to keep it then next year I want to maybe get the power up a bit more.

 

The car could have been mapped to higher boost but we felt comfortable at around 630 rhhp wouldn't put "too" much stress in the stock bottom end. I see people like Hodge, Jamesy's old one running standard pistons/rods with uprated caps and bolts and getting big figures (850/900)...

 

Just wondering is it as simple as getting billet main caps, arp main studs etc to make it cope with 850 ish...? I could then increase boost and see if I could get maybe 850 bhp. The head is a race spec from Dude, with 280's and uprated springs, I have arp head studs already, twin walbro's (the lines would need improving). I undertand there are LOTS of other supporting mods but the car has most (if not all) off the top of my head that it might need...

 

Any input from you guys please.

 

Also maybe turbo choice for 850/900 bhp incase I change that at the same time.

 

:thumbs:

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Big difference between RHHP and RWHP, no offernce to jamesy or hodge but them cars are never near that claimed flywheel bhp.

 

Billet main caps i dont think are needed till 1000+ real bhp.

 

Go over 2bar boost and i would be fitting L19 head studs.

 

Billet 6766 have put down 950 rwhp.

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Guest Rsand85

Im also quite interested in this topic at the moment as to what crank/rods/pistons those who are running the high end Hp figures are using

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So would I benefit from stronger main studs...? Would this allow to safely increase the engine to around 800 fwhp? Will be changing the turbo, 6766 divided with the larger a/r looks pretty good for what they are...

 

You dont need the main studs BUT they are nice to have, 2J's dont suffer bottom end problems, no need for a head either till you want over 1000 hp, I would just put ARP rod bolts in.

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You can change the rod bolts without pulling the head as well

 

Well it's got the head off you already on it... Sounds good to just do the rod bolts for peace of mind, then get a faster spooling turbo and aim for 850 bhp, get a bigger intake and TB and sort the fuel lines out properly (to dual feed on the rail).

 

What labour costs for that Dude...? pm if prefered.

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You again dont NEED a TB and intake Add, but nice to have, I would say a Greedy and diff turbo would see 850 with Quicker spool quite easily

 

Yeah, I think that's the plan for next year if it stays. TB and intake to make the engine look nicer (and to add a bit extra hp), and a faster low down spooling turbo. I like the sound of these small turbo's making 800+bhp amd being on full boost around 4k :)

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my view is the initial limit is the rods, maybe the L19 will come in handy depending on boost, but everything else (caps etc) comes later

 

the rods are marginal somewhere up around the 850rwhp mark on a dyno dynamics (rwhp not bhp) in shootout6 mode, ie higher than most people think. maybe a little more, depending on the balance of boost/revs used to get there. mine did within a hair of that on the factory short motor without issue. oem mains caps start cracking around the 1000rwhp mark. so at the point where you go into it for the rods you may as well also do L19 head studs, billet mains and pistons.

 

youre in the clear til pretty big power at that point. unless youve overcapitalised, by then youre running a t6 frame 80mm+ turbo spinning ~9k ballpark to properly use it and your next problem will be keeping the oil up to it under sustained high rpm. thats claimed a couple motors at the tx mile turning 92XX rpm through the traps in 5th, the solution being dry sump. but in the real world theres obviously limited opportunity for that sort of extreme sustained 5th/6th gear stuff, so most people will never get there.

 

below the gasket, good pistons/h-beam rods/billet mains caps will see you through just about anything. spend any spare cash on frequent oil changes and lightening other fast moving stuff like shimless buckets, they save a heap of weight. people often overlook maintenance on these cars in favour of the next modification, that can make for more hassle in the long run

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