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The mkiv Supra Owners Club

ported head?


c0c4in3

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Stolen from SupraForums.com :

 

Intake port gasket matching before

http://memimage.cardomain.net/member_images/10/web/694000-694999/694969_81_full.jpg

 

 

Intake port gasket matching after

http://memimage.cardomain.net/member_images/10/web/694000-694999/694969_97_full.jpg

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Thanks a lot... I thought ported means something like changing the position of the engine :D Sorry for beeing dumb... But porting for me means moving something from here to there... But thanks a lot for your replies... Appreciate that.

 

Have a good weekend mates :-)

 

Oliver

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If anyone is iterested in this, I now have agood contact for porting. £700 a 6pot head for a good street port. The guy does alot of work for Anderson Race engines, and been doing it for a long long time, so Im guessing his work is as good as other people if not better.

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Not a lot :) Not these days. The MkIV cylinder head is reknown for being really good out of the factory. The old ford xflows responded well to porting and polishing because they were shit to begin with haha. Hence this job has a reputation for getting good power gains, but in reality not much is to be done with modern heads.

 

-Ian

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It's the "icing on the cake" so to speak
and also "the law of dimishing returns". It's a lot of work for very little gain.

How many hours would it take somebody to port/polish a TT head? I've done a couple of single cylinder two stroke bike barrels and that took forever.

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I, too, used to believe that porting heads for turbos was not worth the effort - mainly because I was relying on other people's knowledge at the time, like Graham Bell's books etc.

But when I ported (mildly) my bike's head back in 1989 the difference was quite noticeable and that made me question 'conventional wisdom'

 

That porting job was my first one and it was kinda rough too. The engine was aircooled 2valves/cylinder (ZX750E1) so maybe the starting point was lower - who knows.

The truth is that at 10psi it was making around 10 extra bhp and the cyl head temps were lower too (non-intercooled!)

 

On the Calibra I saw the same power at a couple of psi less with a mild porting job (Using a Dremmel, no valve guide grinding or anything spectacular)

 

If I had the supra head off for some reason, I would do a mild porting job on that too. Basically a cleanup, gasket matching and smoothing out of casting marks. Along with valve-lapping surely it can't hurt, and the extra effort involved is not that much anyway.

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All cyl heads are nowadays 3-angled, at least for 'performance' engines with any pretensions of quality

 

Back on the supra, if going for a full 'porting' job beware of the angles of inlet and exh ports. They are not 'straight' but that is part of the design.

I've seen americans trying to 'straighten em up' eliminating the intake swirl unknowingly. Blessem.

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If I had the supra head off for some reason, I would do a mild porting job on that too. Basically a cleanup, gasket matching and smoothing out of casting marks. Along with valve-lapping surely it can't hurt, and the extra effort involved is not that much anyway.

fully agree with john here, this is exactly what i did with mine when i did the valve seals, matched the ports, not really any casting lines to clean, polished the combustion chambers, valves and exhaust ports but left the intakes the rough cast finish, i have no idea what performance difference it made to the car as it happened with a shit load of other mods, it kept me happy as a pig in shit for a week and was just a far more complex version of the 2 strokes i used to mess with

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Guest Usmann A

Porting i think helps when u want to achive a big air mass in and out of the chambers. The supra ports promote swirl on diff chambers, and the port angle will naturally cause some tumbleing of the mixture.

 

Velocity n that doesnt really matter as much, cos we are ovb wafting some air in there, but slight touches of the bowls can be sweet, eventhough its pressureised we can still control how the air is channeled even at high flowrates.

 

When i port supra heads, i do a tidy up of the ports, some heads are brill from the factory, others i seen are mismatched when it comes to gaskets, one off my dads car was a brill head.

 

I always polish the exhausts as i dont want any particles or buildup of carbon deposits,over time it will, but this will slightly delay that.

 

They are other things u can do to therchambers, n if u a big porter make sure u get a burette as u dont want things being uneven.

 

itll all be worth it in the end. :)

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