arrows coupe

[arrow]

Arrow just laid down 653rwhp. At powercruise. NO dyno fan

[fatTG-TE]

what did the head flow if u got it tested? also is it a big port big valve g200 head?

[arrow]

The head is a big port big valve G200 head. 2mm oversize valves. I used this head so i could have flat top piston and still have low comp. the engine is at 8 to 1. I ported the head and the ports are big. bigger than you would go with a N/A engine.

[fatTG-TE]

ok cool I have same head but I found that the other g200 big port head I have has slightly smaller combustion chamber 1 is 87mm and other is 84mm. I have 44mm inlet and 37.5mm ex

[Jonno]

Cough....

[arrow]

I pulled the engine out a for a look and check a couple of months ago. the bearings were all good for the amount of work they had done. The exhaust valve seats were a little worn and required a recut. The main problem I found was the valve springs were shot. they had lost 25lb of seat pressure from when they were fitted. And they were never set up to go to 40 PSI to start with. So i fitted a new set of spring with more set pressure. I had to get a new clutch aswell the last one was slipping at 650HP. So the crank and new twin plate clutch got a balance job a quick hone and back together it went.

Off to the dyno we went. The new valve springs did there job as it made more power on the same boost. We wound the boost screw up 49psi and it went 830RWHP with a bit of hopping on the dyno. i got nervise and wound it back to 46 psi it went 788 back to back.

I have just come back back from the summernats on the friday it went 796. then today on the first big pull it went 798. i wound the boost up and it went 825RWHP. it was at 49 psi at max power and just hit 50 psi at full revs.

So it looks like the gem car has set a new 4 Cylinder record for any 4 cylinder at a dyno comp. and i think its cool its a G series engine.

I will put up some photos over the coming days. time for a beer.

[Holden202T]

congrats man

[Anthony_Gemini]

I missed it live unfortunately ,, but heard the news ,
Huge congratulations ,,

[DR_GEM]

Mate that is unbelievable and an absolutely fantastic result!

Well done and would love to see this beast in action

Gives me hope for my little s@*tter too!

Mick

[LOK15]

it'll make geminis popular again no doubt

[Holden202T]

what do you mean, i thought they already were ??

[DR_GEM]

By the way I love the rich dip in afr at peak torque. Also good to note this was done a conservative 11ish:1 afr

Question though - With the alloy head wouldn't it be wise tapering down to a 10.5:1 in the last 1000rpm to keep the head cool?

Mick

[arrow]

By the way I love the rich dip in afr at peak torque. Also good to note this was done a conservative 11ish:1 afr

Question though - With the alloy head wouldn't it be wise tapering down to a 10.5:1 in the last 1000rpm to keep the head cool?

Mick

Good pick up DR Gem. The tune is richer normanly i try to keep it at 10.5. I did not know at the time but the alternator s*#t it self on the first pull. The battery voltage dropped to 10.5 volts on the last run. the fuel pumps, injectors and coils did a good job holding it together.

i need to make a bigger pulley for the alternator i think its spinning to fast.

i think its got more in it power cruise may see 55psi. ( just don't tell my wife ).

[DR_GEM]

By the way I love the rich dip in afr at peak torque. Also good to note this was done a conservative 11ish:1 afr

Question though - With the alloy head wouldn't it be wise tapering down to a 10.5:1 in the last 1000rpm to keep the head cool?

Mick

Good pick up DR Gem. The tune is richer normanly i try to keep it at 10.5. I did not know at the time but the alternator s*#t it self on the first pull. The battery voltage dropped to 10.5 volts on the last run. the fuel pumps, injectors and coils did a good job holding it together.

i need to make a bigger pulley for the alternator i think its spinning to fast.

i think its got more in it power cruise may see 55psi. ( just don't tell my wife ).

10.5 is safe. No doubt could make a little more if you leaned it out a bit but given the power you're making does it really matter

I too am looking into larger alternator pulley to maintain voltage or altenatively adapting a different alternator.

Curious to know timing at peak torque and redline (unless of course this is secret squirrel stuff which I would totally understand)

Seems from the boost curve in previous charts that you're tuning for rich spool and thus i assume low to moderate timing instead of mbt?

Mick

[F3ARED]

You probably already know, but for those that dont two pictures of this and a small caption re-iterating that it destroyed the 4cylinder class @ Summernats in this months Street Machine.

Well done again scott