Turbo/supercharging??

storm_rider_ · Post by **storm_rider_** » 01 Sep 2006, 13:22

How well do the twin cams take to being supercharged or turboed??

I assume you need forged pistons and rods. Can the head be played with to make alot more power??

GeminiCoupe · Post by **GeminiCoupe** » 04 Sep 2006, 11:57

It depends on what you need from the car. The standard pistons will be fine with relatively low boost and spot on tuning - bare in mind that the DOHC runs fairly high compression standard and that it wont take too much detonation for the pistons to fail.

Head flow is good, particularly when modified. Its a wide angle head so the transition from port to seat is fairly smooth, ive heard of people getting as high as 220hp flow - Think that was Denny's head in the 117.

Forged pistons arent a must, but it would be adviseable to get some made up with a lower crown height if you intend on running big boost/power. Custom rods ARE NOT needed - standard items are already forged and can support in excess of 450hp when shotpeened. The only thing that can kill them is poor oil supply to the bearings, which in turn leads to bearing failure and in turn creates a big mess..

Nick-

Tassie ZZ/Z · Post by **Tassie ZZ/Z** » 05 Sep 2006, 11:06

my head's flowed to 230....................... shame my motor aint going!

archangel62 · Post by **archangel62** » 05 Sep 2006, 16:49

Nick when you say "poor oil supply to bearings" do you mean the infamous cam bearings, or are you talking about rod/crank bearings? I thought the rod/crank bearings were fine on these engines - should I be worried?

My understanding is that forged pistons cost a good $1200+ to have made, even locally... Anyone know of cheaper? I was estimated at about $400 to have the stock pistons machined to decompress... Would this be at all worthwhile? I'm leaning towards not bothering and just saving for forged pistons...

GeminiCoupe · Post by **GeminiCoupe** » 05 Sep 2006, 16:59

my head's flowed to 230....................... shame my motor aint going!

WTF what have you done to it mike? GET IT GOING MAN this is sounding better and better by the day. Sell the twin carbies, sell the zed and put quad throttle injection on it

Eli, i meant that poor oil supply to the rod bearings can cause rod failure. The engines are well oiled and strong however the standard sump isnt baffled - turning sharp can cause a drop in oil pressure and thus oil supply Geddit?

archangel62 · Post by **archangel62** » 05 Sep 2006, 17:30

Oh right... Sh*t... lol

Welding baffles in - good or bad idea? I know a welder...

Tassie ZZ/Z · Post by **Tassie ZZ/Z** » 06 Sep 2006, 19:32

Yo Nick

230 is the figure I was told - have not proof though!

I had a dude in Hobart build my motor - he copied the specs from a guy he knew who ran a DOHC motor in NSW Club Rally.

The head was sent off to an old guy in Hobart who is well known for doing race heads.

Cams went off to CamTek for mod.

Bottom end all done.

This thing cost me heaps, it revs but no power......WTF............ He always said that the thing was too radical for carbs - I'm thinking that's crap and I was had.

8,500rpm rev limited
9,200rpm max I hit

but no power. std intake????? std injectors???? Wolf 2d?????

weber style throttle bodies would be good..............

it upsets me........................................... sorry for talking shyte.

Mike.

archangel62 · Post by **archangel62** » 17 Sep 2006, 04:56

What power band were the cams ground for?

I drove a G180Z which had been balanced, blueprinted, freshened up etc, but the cams were designed to spool a turbo (but it was NA) and it would only pull from exactly 3800rpm to exactly 5400rpm. Absolutely nothing after that, the power would just stop completely above/below that.

Otherwise...? Injectors maybe as you said? The ECU tune? Stuffed o2 sensor even??