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The mkiv Supra Owners Club

To Port or not to Port?


veilsideTT

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Hi all,

 

Does anybody have any info in respect of having my Head Ported and Polished? I know where I’m going to have it done but i need some reassurance before I go through with it!

 

I will be at BPU with a Front Mount.

Don’t want to run anything over 1.2bar (1bar daily use)

 

My mods will be (when rebuilt)

Full de cat, Nur Spec, FCD, MBC/EBC (Can’t make mind up on that one) and a 3 Row.

My car is a UK (Leave it dude!!!) Auto

 

Any input of advantages/disadvantages and also things I should be wary off would help me a lot.

 

Thanks

Scott

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I've heard that the combination of:

*Good stock intake port design

*Forced induction

*The limitations of the exhaust manifold and turbo housings (as you are sticking to stock turbos)

 

Makes spending a large wedge of cash on a port & polish job a poor bang-per-buck proposition. Probably better off spending the cash on getting a set of HKS cams in there.

 

-Ian

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Originally posted by Ian C

I've heard that the combination of:

*Good stock intake port design

*Forced induction

*The limitations of the exhaust manifold and turbo housings (as you are sticking to stock turbos)

 

Makes spending a large wedge of cash on a port & polish job a poor bang-per-buck proposition. Probably better off spending the cash on getting a set of HKS cams in there.

 

-Ian

 

Agreed

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Chesman Motorsport said they will do this for around 200!

 

What’s the Cams thing all about then? I’m intrigued? Could have sworn I remember reading that HKS cams make your car idle like a sack of shit. Is this right?

How much for a set of HKS cams, what are the advants/disadvants of running these at BPU?

 

So I cant get any takers who are ‘for’ the port and polish??

 

Scott

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I'm against. Very little point on a forced induction engine IMHO.

 

In fact I'll go one better: You get a smaller boundary layer for the same total airflow on a rough surface than you do for a smooth one. The effect on an intake port is to make the air "stick" to the lower surface better, giving you a larger theoretical orifice for the airflow into the cylinder.

 

It's not as cut and dried as that, though, because it depends on the port design whether the boundary layer effect in a smooth port or the frictional losses on a rough port dominate.

 

(Not my knowledge BTW. I knew the two different theories, but there is an aerodynamicist sitting in the next cubicle :cool: )

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Originally posted by veilsideTT

Chesman Motorsport said they will do this for around 200!

 

Plus the actual taking of the cylinder head off = lots of work even if you do it yourself. You'll take the turbo side apart, and new gaskets to put it back together costs about £100. New head gasket required as well, obviously, and these aren't cheap. And a new intake and exhaust side gasket. And new head bolts. And if you did it properly new coolant, possibly an oil change. Kinda adds up :) More like £400+ even if you do the labour yourself. And the tedious running in period of a couple of thousand miles, then taking most of it back apart to retorque the headbolts.

 

What’s the Cams thing all about then? I’m intrigued? Could have sworn I remember reading that HKS cams make your car idle like a sack of shit. Is this right?

How much for a set of HKS cams, what are the advants/disadvants of running these at BPU?

 

So I cant get any takers who are ‘for’ the port and polish??

 

Scott

 

They introduce a slight 'miss' to the idle, sounds great, affects nothing. MVP Motorsport are selling a set of HKS cams for less than £600 including shipping I believe. Advantages = gives more wellie and pulls strongly up to 7000rpm. Disadvantages = slightly lumpy idle, there is apparently a slight (10bhp ish) loss in low-down power, can't say I noticed it.

 

-Ian

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Originally posted by veilsideTT

Ian, i forgot to mention that my engine is in peices all over the garage floor.

 

Head is fully stripped anway, thats why i wondered if i should have the port and polish done whilst its all out and stripped down.

 

Cheers

Scott

 

Heh, well, that makes quite a difference :)

 

Personally I still wouldn't bother, but £200 to be able to put "custom port & polish job" in your sig might be considered worth it :D After all, it's less £ than a fancy gauge and it'll have a darn sight more performance impact than one of those.

 

-Ian

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I am sure this has been discussed before and the conclusion was unless you can do something about the restrictive exhaust manifold it reallyi s not worth it. Having said that I expect all the costs mentioned above would have been a contributory factor to the decision. I am not sure now far Chris Wilson took the porting if any on Nic’s head. Might be worth chatting to him.

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Originally posted by Ian C

Plus the actual taking of the cylinder head off = lots of work even if you do it yourself. You'll take the turbo side apart, and new gaskets to put it back together costs about £100. New head gasket required as well, obviously, and these aren't cheap. And a new intake and exhaust side gasket. And new head bolts. And if you did it properly new coolant, possibly an oil change. Kinda adds up :) More like £400+ even if you do the labour yourself. And the tedious running in period of a couple of thousand miles, then taking most of it back apart to retorque the headbolts.

 

 

But it's so easy in Gran Turismo?! :blink:

 

:looney:

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