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Cams, thoughts?


smithy23

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Just bought some 272 hks cams, understand it may need reshimming, what is this, done a few searches and still cant work it out? Are they overkill for uk spec bpu? And how will a v-con pro or e-manage help me, just a standard ecu at present, will it be hard for the mechanic to get the right afr through the rev range?

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Just bought some 272 hks cams, understand it may need reshimming, what is this, done a few searches and still cant work it out? Are they overkill for uk spec bpu? And how will a v-con pro or e-manage help me, just a standard ecu at present, will it be hard for the mechanic to get the right afr through the rev range?

 

hi mate they will need reshimming and are probably overkill for your current spec.They are better suited to a medium to big single twin kit.

Some people also recommend doing some head work to get the full advantage out of them.(not speaking from personal experience though)

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You think id be better looking to swap them for some 256's or similar? Got them for 400 notes the other day, didnt seem a bad price for new.

 

hi mate 256 in 264 out isnt a bad combo for bpu,or maybe 264 /264

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Might have a go at swapping, know much about the fueling computers, piggybacks out there?

 

 

yeah ,you going for uprated drop in injectors or UK spec ones?

would probably stick an E-manage ultimate on .Not bad for the money.

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...Are they overkill for uk spec bpu? ..

It's not a matter of being overkill, in this case they are not a good match for the needs of your engine.

Being a UKSpec it does have turbos with slightly less restrictive A/R ratios, but these cams are still off the mark.

They will take away quite a bit of midrange in exchange for some easier breathing at top revs.

 

They are meant to be used with singles really.

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personally i'd go with a mix.

 

 

264/272 from what i know, these r good if u change your set up in the future to higher hp.

 

264 or smaller are similar to stock.

 

not sure how these work on the specific supra, but on a slightly modded car stock cam's aint half bad.

 

and like others said 272/272 will give better high rev power although you might loose torque lower down

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IMO they're not really suited to a stock based setup at all. Aside from being better suited to larger turbos, they're really designed for top end power.

You'd still be making good usable power way up the rev range, but you're stock rev limiter would kick in and prevent most of the gains they can provide.

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Thanks for the input peeps. Ive got the uk 550cc injectors by the way. So an e-manage or v-con will simply allow better tuning of the a/f ratio through the rev range, but what other functions can it do for the money?Also the shimming of the new cams needs changing, is this the gap between the bottom of valve to the piston, governed by the thickness of the shim with the cam lobe sat atop???

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As said already, if you can, swap the cams for i256/e264, the 272's are not suitable for a Supra running stock turbos, you'll just lose out mid range and gain very little, if anything at the redline.

 

A stock Supra is mapped to run at 0.8bar, the stock ECU is mapped to take into account performance, emissions, fuel economy, reliability, etc. The UK Supra especially, is meant to be set up quite rich and will also probably be set up for more stricter European emission regulations.

 

An aftermarket ECU such as the emanage or emanage ultimate allows the fueling and timing to be adjusted to maximise power. It also means you can map for running higher boost pressure (when combined with aftermarket pressure sensor).

 

If interested I am currently organising a discounted Group Buy for the Emanage Ultimate, this is one of the best aftermarket piggy back ECU's available for the money. See details here:

 

http://mkivsupra.net/vbb/showthread.php?t=78232

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To answer the initial question :) Shimming the cams is when you make sure the clearances are correct between the cam lobes and the valve bucket.

 

The buckets sit on the valve stem and push against it to open the valves. The cam lobe pushes the bucket via a shim that sits in the top of the bucket. This shim is a simple flat disc of metal that is a certain thickness, and it's this shim that you swap out in order to get the correct tolerances (gap size).

 

The gaps are 0.15 to 0.25mm intake and 0.25 to 0.35mm exhaust. If the gap between the shim and the round bit of the cam lobe (i.e. completely shut valve) is outside of those ranges then you need a thicker or thinner shim.

 

272 is overkill. 264 and 256 are not that similar to stock, they have a lot more lift and duration and you can get very good results with them. For most of us here they are as much cam as we'll ever need.

 

-Ian

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You dont think theres going to be much market for the 272s then Ian? Thanks for explaining the shimming to me, got a much better take on it now. So if a shim is too large, its just a matter of trimming a little off, but if its small, new ones at £14 a pop. Thanks for that Ian

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Well, replacing the shim with the right sized one is I think the way to go, there are many part numbers for them, each a weeny bit different from the last so you can pick and choose exactly which shims you need.

 

Fourteen quid each?! I'm glad I had spares that fitted when I did my cams and stem seals!

 

-Ian

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