Head Porting

[Entaran]

Dear people with brains (IE: Obviously not me)

I want to send my head in to get ported, at the same time it'll have cams/etc all fitted.

Problem: I have no idea what to ask for.

Valve jobs??

Porting amounts??

What works? What should I say? What should I ask for?

I'm only looking for a mild car, something I can street around in, not an out and out race car.

baz? dre? jon? sloth?

 

[Entaran]

I should also add that i'm replacing all parts in the head except rocker arms:

Lifters
Cams
Cam Gears
Rocker cover seal/gasket (Obviously)
Valves
Valve Springs
Valve Retainers
.... i'm sure i've forgotten something

 

[CLuTZ]

Whats wrong with your head? (the one on your car)

If its all good, i'd just look at other ways to make some more power before you go looking at getting stainless oversize 3 angle valve jobs.

If its poked and it needs a rebuild, maybe, but the dual runner cyclone is more than enough to meet your needs for the time being- some cams, bigger turbo, fuel, management and free flowing zorst and i/c will get you some tasty results.

dre

 

[CLuTZ]

Another option could be at looking at an EVO head?

but if it aint broke- why fix it?

these engines take some serious punishment without folding!

 

[Entaran]

I'm doing it all at once because of my "down the track" plans.

Head first.

And i'm not going for oversized valves, just one piece stainless items.

I'd go oversized if it was a racecar.


... I'm looking for that lumpy cam idle It's horny.

 

[CLuTZ]

I'm doing it all at once because of my "down the track" plans.

Head first.

And i'm not going for oversized valves, just one piece stainless items.

I'd go oversized if it was a racecar.


... I'm looking for that lumpy cam idle It's horny.

ok, well- goodluck!!

 

[bazeng]

u cant really go evo, some would say its a step backwards.. they have much smaller ports.. u will also need another inlet manifold also.

due to the size of the vr4 ports, if u go any bigger, it'll pretty much be a raceport..

i could only suggest for street

cams / cam gears / lifters / valve springs / u could do retainers if u wanted.

if u pull the head off u'll also need a new head gasket.. maybe increase compression??.. get a bit more grunt down low..

save for the big build up.. the head is plenty for the street!..

do as dre has done.... the results speak for themself...

 

[Entaran]

Ok, so all I should be looking at is matchporting the inlet/exhaust rather than actually INCREASING the size of it?

That is going to save me a bucket load of cash.


Out of interest... what's a 3-angle or 6-angle or whatever valve job... what's it do? Is it for installing oversized valves or can it be done on standard ones?

 

[matress]

yo barry,
about those evo heads being a step backwards, there seems to be a bit of conflicting opinions about that. some people seem to prefer the smaller port evo head for great air velocity/better low-mid power.
depends what the application is i guess?

 

[bazeng]

yeah, i understand that.. but for flow, i believe the vr4's are better

i believe the advantage of the evo heads are (for the more extreme) when porting, u can shape the ports as you like... whereas the vr4's dont have much meat left.. therefor the evo heads can in a way be ported to suit the application whether it be drag / track etc...

vr4 heads are considered MASSIVE for a 4 cylinder...
good for drag cars =)

BUT.. the evo heads are supposably better in one way with the way the ports aim at the valves, making it a better angle...



as for the valves

3 angles = they actually give the valve 3 different angles..
5 angles = they give the valve 5 angles..
radius = they smooth it out

its to do with air flow and turbulence etc..

different builders swear by different things...
i've spoken to some who go with the radius, others who go with the 3 angles...

(these are cut behind the valve where the valve seal with the head)

can anybody confirm on this??

this is my understanding from watching my engine builder rebuild heads etc..

as for the evo head, there are numerious topics on dsmtalk.. and basically i've just summarised multiple pages of discussion and opinions..

 

[brisvr4]

There seems to be a fair bit of good info in this thread Lorrie.
Keep it simple.
http://www.galantvr4.org/ubbthreads...=272711&page=1&view=collapsed&sb=5&o=&fpart=1

 

[AUSVR4]

if VR4 ports were better why would mitsubishi engineering go smaller? theres a good thread about it on nzmmc somewhere. ill find it when i get the chance

 

[Entaran]

if VR4 ports were better why would mitsubishi engineering go smaller? theres a good thread about it on nzmmc somewhere. ill find it when i get the chance

This is a stupid statement, I'll show you why.

When designing a car for mass production, unless it's an out and out supercar (And even then, they have these considerations), you must take into account:

Driveability - Nobody will buy a new car that's rough
EMISSIONS - Emissions regulations got tougher, intake CFM is one way to control it
The fact that E123 have a different turbo to the VR4
COST
Manufacturing ease
and so on

There's tons of factors. Performance is WAY down the bottom of the list somewhere. All car manufacturers who make sports cars are aware of the aftermarket industry. The fact remains that MOST PEOPLE are happy to drive a "stock" sports car as it's fast enough/etc for them. Only some of us will modify a sports car to make it faster/harder/better. So on. Thus, you may find the intake was changed solely for driveability with the different turbo. Or the fact that the cams are different and the valve lifts are too, therefore the intake might have been changed for that matter.

Getting the drift?

 

[CLuTZ]

if VR4 ports were better why would mitsubishi engineering go smaller? theres a good thread about it on nzmmc somewhere. ill find it when i get the chance

This is a stupid statement, I'll show you why.

I think he was trying to say theres alot more into it than the obvious, just like what you were trying to say

 

[bazeng]

They both have their advantages.

Its all up to what you want and what you will do with it..

i'd go vr4, save costs on porting...

others would go evo, etc etc...

and about the vr4 to evo thing..

its like comparing the evo6 to evo7, which change the design when the 6 is faster?!?!...

and compare the tco6 and the tco5...
they went smaller, why?? drivability.. not because its better..
i guess some people dont like the lag =)

but i know if i had the choice i'd go the bigger tco6

like lorrie is saying, not as simple as it seems..


I dont think their is a right or wrong answer with this one..
its all personal preference...

 

[AUSVR4]

took me a while to back up my "stupid statement" (i forgot about it) but heres some informative discussion from dsmtuners:

Originally Posted by DSMJim
What sort of scientific proof has "look at it" been turned into? What makes you think that you will gain HP with a 1G head over a 2G head just because the intake runners are larger?

The larger runners on a 1G head have a much larger angle into the valve, this actually slows the air entering the cylinder chambers. Generally on a port job of a normal head for racing they raise the chambers not lower them so the entry into the valve is a straight as possible. The angle into a 1G head is horrible because the port is so low already in the head.

The HP increase from a 2g head to a 1g head is from the Cams, and Intake manifold. If your using aftermarket cams and plan on buying a SMIM don't put on a 1g head because you'll end up with no gain and a head that has horrible port design.

Most major racers now using DSM's are using a 2G head and 2g style intake manifold and raising the runners in V8 styles so the air is hitting the top of the valve as straight on as possible. Air flow has nothing to do with the size of the chamber and EVERYTHING to do with the shape and design.

Putting a 1g head on a 2g block is the OPPOSITE of what you want to do. Replace your 2g block with a 1g block and keep your 2g head. Have it ported and port raised and add a set of HKS or Comp cams with a SMIM. This will provide you with a much more potent street engine.

Originally Posted by AMS Eric #2
Use the 2g head!! The castings on 2g heads are far superior to 1g castings. They have more alluminum in the lifter bulkhead to reduce flexing and less problems with casting shifts than 1g heads. The intake ports are smaller yes, but they do not seem to be a restriction of any sort. The Evo 8 heads have the exact same intake ports and we are making 600+ whp constantly on completly stock unported ones. Our shop car's intake ports arent opened up that much at all and it makes over 800 awhp.

Use the 2g head, drill the head bolt holes out to fit the larger 12mm studs, find yourself an Evo 3 intake manifold, and you'll have the same top end package as an Evo 8, which has been proven to consistantly outperform 1gs. It will save you money, make your swap far easier and WILL outperform a swap with a 1g head/intake, much to everyones dismay.

 

[EVO-00X]

But where are the flow bench tests comparing both heads? lol :lol: I actually wanna see the difference in cfm flow as numerical data so I can see the difference in black and white rather than people's opinions - professional or otherwise :wink: I'm sure its been done and is up on the net somewhere. Is the difference HUGELY ASTRONOMICAL?, is it a mere 2% better flow at a very high rate? does the 1G head flow better within a specific or lower range even? unknown? :roll: Without 'actual' proof I cant see too many people rushing out to put EVO heads onto their VR4 engines for a small gain unless they are die hard racers going for every ounce of power :roll:

 

[EVO-00X]

OK... looked everywhere and actually found some flowbench comparisons on my computer from DPR Racing http://www.dprracing.com/ back in 1998!! lol :lol: . This info I suppose is pretty hard to come by so this may come as a bit of a surprise to some of you for airflow comparison between the stock 1G and 2G vs DP's own head modifictions By those tests the 1G (VR4) flows more than the 2G (EVO), especially on the intake side at higher lift :shock:

I knew all those GB worth of info would come in handy one day hahahahaha :lol:

 

[bazeng]

awesome find!!!

btw, whats the dp head?
a ported one by that company?

 

[EVO-00X]

Yeah, well back in 1998 it was. I dunno if they offer them now though but their link is in my previous post. From the findings you can clearly see the stock VR4 head flows more than the stock EVO head... but once you port the EVO head (in the same manner or similar to DP have) it outflows the stock VR4 head. There was no comparison between ported EVO and ported VR4 though which would have been a bit more interesting, although the stock VR4 head still flowed more down low than what the ported EVO head did anyway 8)