Starion Vs Evo Vs VR4

[Galant_GT0]

High guys, so I have stripped my Starion 4G63 and found some unexpected issues. So I have some question.
Is there any difference between the conrods?
Is there any difference between the pistons? (besides oversize items)
I want to swap to twin cam;
Is there any difference between VR4 and Evo 1,2,3?
Can I use a N/A head?
What would the difference be between copression ratios in using a turbo or non turbo head?
What is the reccomended ECM for a twin cam upgrade?

Cheers
Jason

[JDSTAZ45]

I am now in a similar boat with the recent purchase of a twin cam head.....

This link should give you most of the answers...

http://forums.austarion.com/viewtopic.php?t=11874

[YellowJA]

rods same
port sizrs vary
NA head does not have turbo cams
7.8 v 9.3:1

[OLD FART]

Staz pistons only have 3 fly cuts for the valves TC's have 4
You must use TC pistons under a TC head
NA is fine I have one Don't know if the exhaust valves are higher/better quality in turbo heads
You can buy pistons with different bowl volumes to get the static CR you want
Rods are the same length in 63 & 64 motors
Talk with whoever is going to install and tune your new TC BEFORE you buy one
Good luck

[dirtygalant]

High guys, so I have stripped my Starion 4G63 and found some unexpected issues. So I have some question.
Is there any difference between the conrods?

Starion and VR-4 rods are the same, Evo rods are different (thinner, smaller width big end journal and larger gudgeon pin hole)

Is there any difference between the pistons? (besides oversize items)
I want to swap to twin cam;

Starion has cut outs for the SOHC head only, with 3 pockets as opposed to four on the VR-4 and Evo motors. Starion is also 7.6:1, VR-4 is 7.8:1 while Evo ranges from 8-9:1. If using stock Starion or VR-4 rods you'll want to change to VR-4 pistons, or if you're using aftermarket rods to suit the Starion/VR-4 crank and Evo gudgeon pins you can run the 22mm Evo pistons. Or you could even bore out the small end of the Starion/VR-4 rod to accept the 22mm Evo gudgeon pin, but this isn't the most recommended method.

Is there any difference between VR4 and Evo 1,2,3?
Can I use a N/A head?

VR-4 has large ports to be used in conjunction (well at least on JDM models) with a 'Cyclone' manifold which is dual stage with 8 runners of which only half get used under about 4500rpm to promote turbulence and swirl in the combustion chamber. Evo has smaller (but not necessarily small altogether) ports which is arguably the better head to go with. The actual heads between NA and Turbo are the same, assuming you're comparing VR-4 vs HH/HG GSR head, or Evo vs N/A 7 bolt RVR head or whatever you would have there which is about 93 onwards and N/A DOHC 4G63. It's the cams which are different, the valves are the same. So use an N/A head with some VR-4 or EvoII/III cams (Evo I cams have less lift) and voila you have a turbo head.

What would the difference be between copression ratios in using a turbo or non turbo head?

No difference, the difference in compression ratios is via the pistons rather than the combustion chamber of the head.

What is the reccomended ECM for a twin cam upgrade?

It probably varies in what region you are in. Here in NZ a Link ECU is a popular aftermarket ECU choice, but I understand in AU the likes of Microtec or Wolf3D are the popular choices. You could give something like Megasquirt a go if you're willing to try something different - it's a cheap DIY type ECU which you could either assemble and solder yourself or order it pre-assembled ready to use. The advantages would be cost and the fact that the software and code is open source and is continually being developed, but the downside is not many tuners would have had experience with it, but with the help of a friend operating a laptop you can road tune to 90-95% performance capabilities yourself without going onto the dyno.

Cheers
Jason

You're welcome.

[woops]

VR-4 has large ports to be used in conjunction (well at least on JDM models) with a 'Cyclone' manifold which is dual stage with 8 runners of which only half get used under about 4500rpm to promote turbulence and swirl in the combustion chamber. Evo has smaller (but not necessarily small altogether) ports which is arguably the better head to go with. The actual heads between NA and Turbo are the same, assuming you're comparing VR-4 vs HH/HG GSR head, or Evo vs N/A 7 bolt RVR head or whatever you would have there which is about 93 onwards and N/A DOHC 4G63. It's the cams which are different, the valves are the same. So use an N/A head with some VR-4 or EvoII/III cams (Evo I cams have less lift) and voila you have a turbo head.

Thought the cyclone dual runner design was to give two peaks to the torque curve. The idea of having long runners gives good low down torque and shorter runners give good torque in the upper rev ranges due to the resonance of the air entering the inlet.

The turbulence in the combustion chamber would be more affected by the shape of the combustion chamber, thats why the hemi heads were such a revolution in their time.

And also does anyone actually have the dimensions of the inlet ports hight and width of the heads. I have a sonata head and the inlet is about 52mm x 30mm and the exhaust about 50mm x 31mm.

The other thing is how can you identify a VR4 cam vs a N/a Cam. I've tried to find the info on various forums but i haven't been able to find too much. I tried measuring the cam lobe on a set of VR4 cam's i picked up on ebay to confirm if they are genuine and i got about 30.5 for the round part and the lobe was about 35.5. Thing is that i measured the sonata N/A cam and they measured up the same. I don't know about how is an easy way to measure the duration though.

Sorry about the thread hijack.

[dirtygalant]

JDM 'Cyclone' manifold isn't dual length, it's just dual stage - ie two parallel runners for each port of which one has a butterfly valve fitted. It works exactly the same as Toyota's TVIS.

The AMG Galant 'Cyclone' manifold however is dual length runner like the 6A12 and 6G72 manifolds.

[YellowJA]

The NA head comes in two combustion chamber sizes, and hence CR. If the head has 1.6 on the end it is the small one

[dirtygalant]

The 1.6 head also has smaller ports. And to make it more complicated the 4G61 came out with two different bore and stroke sizes, with the later one sharing the same bore size as a 4G67 engine, and thus the 4G67 head was used on the later 4G61 engines.

But we're comparing N/A 4G63 to turbo 4G63 heads here, which the bare heads themselves are the same.

[OLD FART]

The 63 tc heads have a 47cc chamber and the smaller tc motors had a 43cc chamber if my memory serves me correctly

[Galant_GT0]

Thanks heaps for the responses guys. Dirtygalant your a champ.
I have decided to stay SOHC so have just bought a MPI inlet manifold from a SOHC Galant and a 70mm TB from a XF Falcon.
Ordered a bilet fuel rail and looking deaper into ECM's, have bought a surge tank and Bosch 040.

I do have another question though, lol

I am looking to make about 160-180 rwkw, what size turbo? Can I use the stock manifold? What size injectors?

Okay so that was 3 questions, lol

Cheers
Jason

[Galant_GT0]

Thanks heaps guys, thats some great info there.
I have decided to stay SOHC and have just bought a MPi inlet manifold from a Galant.

I do have another question, lol

So I want to get around 160-180 rwkw out of this car so I would like to ask;
What size injectors would you guys think?
What size turbo do you think?
Will my stock exhaust manifold be okay or aftermarket?
What brand of pistons do you suggest? I see CP do some.

Okay so thats more than 1 question, lol

Cheers
Jason

[redzone]

have a look at my old orange car's thread, i ran a KKR430 and had MEGA response and 211kw atw ;)

[Galant_GT0]

Thanks mate, you got a link?

[redzone]

found it:

http://forums.austarion.com/viewtopic.p ... e&start=30

i should update that thread actually, it made 289.3rwhp with an intercooler change.

currently it's in pieces, he's getting it painted back to silver again and more engine mods and a hatech E8.. also it has the 17 inch mahdi mesh wheels on it now that i ran on the JB for a bit..