Twin cam conversion

OLD FART · Post by **OLD FART** » Tue Apr 17, 2007 5:34 am

I have seen Kyles work & in my opinion it's first class .He uses merge collectors 2 ensure the best flow to the turbine blades I think he charges about $900 for a 4 cylinder

Carr-e Staz01 · Post by **Carr-e Staz01** » Sat Jun 23, 2007 7:46 pm

hey guys have an updat on my conversion. i haven't done much as my casc flow is really poor at the moment. so i havent had any fab work done but have been wiring my microtech up and other bits a peices. i took some pics so here they are,

the old girl has come a long way since i first brought her.

:beer :beer

redzone · Post by **redzone** » Sun Jun 24, 2007 7:52 pm

^^^ u might wanna resize those pics mate they're huge!

and what is with 6boost going on about "merge collectors", thats like the toyota O2 advantage.. bloody hype LOL seriously who doesnt make manifolds that point the exhaust gas putts towards the turbo??

like i'm sure his work is awesome, but fkn hell!

BrendanUK · Post by **BrendanUK** » Wed Aug 01, 2007 8:12 am

This may seem a bit stupid but what benefits do you get from a twin cam conversion? Do the benefits out weigh the hassle of doing it? Over here in the UK it's just not done, or at least not by many, i can think of 1 UK car and thats Neils which is a full on race car.

It just my engine is getting tired and I've sourced a spare to use as a basis for a rebuild. I know my way round a set of spanners and i think i could do this conversion but just don't see what difference it makes to be worth the hassle over a bigger turbo, forged pistons and MPI?

JD_Stazza_Brendan · Post by **JD_Stazza_Brendan** » Wed Aug 01, 2007 8:17 am

Main advantages are
-Greater avaialability of stock parts for twin cam
-Enourmous range of aftermarket parts from cams, valves, sprockets, fuel rails, exhaust maifolds (low mount) etc

Main disadvantage is cost

BrendanUK · Post by **BrendanUK** » Wed Aug 01, 2007 8:30 am

And performance wise? surly buy the time you've sourced the parts you need, done the conversion a big turbo, decent internals and mpi (all parts you'd need with the conversion) will give the same results, after all cams can be custom ground from billet, and i can get parts for my head here in the UK.

It seems it may be beneficial for what you can/can't get out in Oz, but I'm gonna need more convincing for me to do it.

JD_Stazza_Brendan · Post by **JD_Stazza_Brendan** » Wed Aug 01, 2007 9:10 am

Im all for SOHC, you can get high streetable power from a SOHC.
Im going high power SOHC in my JD as it keeps it more original (although the stuff hanging off it isnt).

DOHC also has the upper hand as its a newer design. SOHC turbo head would have been designed in very late 70s whereas the DOHC was during the midish 80s.

Fine tuning of DOHC would be eaiser if fitted with adjustable cam gears so exhaust and inlet timing can be adjusted seperatly whereas the SOHC cannot.

I dare say on a high power motor the DOHC would idle better as well due to not needing as wild cam design as the SOHC

BrendanUK · Post by **BrendanUK** » Wed Aug 01, 2007 9:32 am

Thats what i thought, SOHC will provide good power, I'm talking 300-350BHP. I like the idea of twin cam but just don't see any real benefit to it, to be honest other than "look what i did" bragging rights. Performance wise i can see how it makes things easier but if you spent the money doing the conversion on a SOHC you'd get the same end result in terms of power, performance etc if not more.

Thanks for the help, SOHC it stays :D

redzone · Post by **redzone** » Wed Aug 01, 2007 6:18 pm

i'm all for either, it just depends on a few things.

are u talking 3-350bhp at the wheels or flywheel? if its at the wheels u will find it a lot easier with the twin cam. flywheel readings then thats a walk in the park for a sohc..

a twin cam will have a wider rev range than the single cam

check out the port size difference between the sohc starion head and the dohc, especially the naturally aspirated and galant VR4 heads..

DanVR4 · Post by **DanVR4** » Fri Aug 03, 2007 11:10 am

Whether the twin cam has a greater potential for power is an argument I'm going to get into, but I will say this:

The twin cam can put out moderate power (say 300whp) with far greater ease than single.

For those not just interested in power, the twin cam has improved drivability (ie city driving)

dirtygalant · Post by **dirtygalant** » Fri Aug 03, 2007 12:33 pm

Shit yeah I can fully agree with going DOHC.

I've owned an E33A DOHC 4G63 non turbo Galant before, and the 160hp it spat out felt way better than the 150hp my SOHC Turbo 1.8L Cordia had. The power band of the SOHC is very narrow whereas the DOHC is so broad in comparison.

My daily driven car, a '93 Galant with a 6A12 MIVEC quad cam 24V V6 engine (same as FTO pretty much) is just so much quicker, more revable and smoother in power delivery than my SOHC Turbo Eterna.

Not to mention the benefits of going DOHC are MULTI point injection being able to run off a STANDARD VR-4/Evo computer which keeps costs down if you had to cut costs somewhere. I reckon if you are going to go through the hassle of going multi point with an aftermarket ECU on a SOHC engine, you may as well spend the extra and go DOHC at the same time.

dirtygalant · Post by **dirtygalant** » Sun Aug 05, 2007 11:55 am

Hey guys I've read over this thread a few times as I'm planning on doing the DOHC conversion to my Eterna at the end of the year.

I am going to use:

* original SOHC block (identical to Starion, can't use VR-4 block as it wont bolt to my gearbox)
* RVR DOHC head (same style as Evo 1~3) with Evo III cams
* Evo III rods and pistons (higher compression than VR-4)
* VR-4 crank, oil pump and front timing cover (although I may use my original crank)

But I'm unsure what to do about the power steering pump, water pump, alternator and air conditioning pump. I see some people have relocated their power steering and alternators to various locations but I wish to retain A/C and keep the alternator (can use VR-4 one if need be) and power steering pump in the same location. Then there's the water pump, do I use the original SOHC water pump (altho I've read it sticks out too far), or use the VR-4 one and modify the water pipe outlet? How would I go about setting up all the pulleys so I can use alt, power steering and A/C at the same time?

As for the thermostat housing, I think I'm going to give moving it to the front of the head a go, as I have the SOHC block which has the larger holes at the rear apparently. I will be using an Evo 1~3/RVR inlet manifold which will be cut and shut, and get an exhaust manifold fabricated up to use an Evo III big 16g TD05 turbo.

I'm basically building the engine to Evo III spec and other than the usual better intake/larger cooler and 3" exhaust I wont do many mods to it, as I want a streetable 250~300hp at the wheels. I will be running an Evo ECU.

Anyone have ideas or comments?

Cheers,
Phil

redzone · Post by **redzone** » Tue Sep 18, 2007 6:06 pm

u cant mix and match generation 1 crank with generation 2 rods man, the journals are different size. just run the VR4 rod & piston combo. u wont notice the compression difference.

and as far as the water pump and accessories goes, just put a starion style water spout on the vr4 water pump, and run all the late model PK type pulleys & brackets etc etc.

JD_Stazza_Brendan · Post by **JD_Stazza_Brendan** » Thu May 01, 2008 7:07 am

Starting to become a wider known conversion

http://www.autospeed.com/cms/A_110289/article.html
was posted today.

Anchor · Post by **Anchor** » Thu May 21, 2009 6:20 pm

In regards to getting power from a single cam, it isn't that hard?

Mine went 297.1rwhp with a standard head and cam. No porting, std valves. Just stronger valve springs. (g63bt)

I'm going wild in the head department now, hoping for about 360rwhp...

Austarion

Twin cam conversion

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