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PostPosted: 16 Oct 2015 18:23 
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Joined: 16 Oct 2015 18:04
Posts: 10
Location: Dunedin
Country: New Zealand
Hey guys, i have a Gen1 black top mivec, it has a MD silvertop ecu for some reason (came with my engine and loom) it has a nice kick but i belive it has a fuel cut at 7.6k, according to a tuning shop it is non programable, does anyone have a RS ralliart ecu they are willing to sell?? I have rebuilt it completely, block and head have been completely recondisioned with 3mm skimmed off the head, i have a 1.5mm OEM metal head gasket for a 4g93t, walboro 500 fuel pump and 2.5" exhaust and intake, compression has tested at a whopping 300PSI over all 4 cylinders, i am running 98octane all the time, i just have a few questions:

1. What ignition timing is best for high RPM opperation?
2.Is there anyway to get around my fuel cut or do i need a new ECU? ( would pay top dollar for a ralliart ECU!!)
3.Are there anymore upgrades i can do to increase power?
4. I would like to do a HIGH RPM build, aiming for atleast 9-10k sustainable, what will i need? Valve springs? Valves? Lash adjusters? Forged rods and pistons?
5. I am also seeking an aftermarket intake plenum or any DIY plenum upgrades!


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PostPosted: 16 Oct 2015 20:24 
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Joined: 04 Jul 2005 13:25
Posts: 1209
Location: Lower Hutt
Country: NZ
I wouldn't touch the head.....it'll be junk.


Hidera1 wrote:
1. What ignition timing is best for high RPM opperation?
2.Is there anyway to get around my fuel cut or do i need a new ECU? ( would pay top dollar for a ralliart ECU!!)
3.Are there anymore upgrades i can do to increase power?
4. I would like to do a HIGH RPM build, aiming for atleast 9-10k sustainable, what will i need? Valve springs? Valves? Lash adjusters? Forged rods and pistons?
5. I am also seeking an aftermarket intake plenum or any DIY plenum upgrades!



1/ evoscan...monitor knock.
2/It depends. Fuel cut is because your injectors are nearly maxed out.
3/Turbo
4/Sustainable? for how long?
5/Make your own parts?

Who cut 3mm off the head?
What a waste of a head.


Have you read through the 4 cyl build threads?

_________________
6G72 mivec Twin TDO5 20Gs up and running.
6G72 mivec bored and stroked to 3.4 litres...Frankenmitsi build
6G74 mivec bored and stroked to 3.9 litres....Frankenmitsi build.
6G75 under construction....4.2 litres bored and stroked.Another Frankenmitsi.


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PostPosted: 16 Oct 2015 20:28 
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Joined: 16 Oct 2015 18:04
Posts: 10
Location: Dunedin
Country: New Zealand
I had head skimmed by an engine recondisioning shop whike they were honing and surfacing my block, i wasthinking of turbo charging, having trouble tracking down81mm firged pistons and 92 h beam rods, if i find a good deal on a 93t block i would otherwise ide prefer to stay all motor


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PostPosted: 16 Oct 2015 20:30 
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Joined: 16 Oct 2015 18:04
Posts: 10
Location: Dunedin
Country: New Zealand
I wanted to up compression and it definately made a difference haha


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PostPosted: 16 Oct 2015 20:35 
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Joined: 16 Oct 2015 18:04
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Location: Dunedin
Country: New Zealand
My motor is a rs black top, only reason it has a fuel cut is because of the silvertop MD mivec ecu, my motor is non modular displacement


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PostPosted: 16 Oct 2015 20:50 
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Joined: 04 Jul 2005 13:25
Posts: 1209
Location: Lower Hutt
Country: NZ
To do it properly, you'll measure the combustion chamber, the gasket and the piston bowl/dish.
Then you can work out the CR which will tell you what octane fuel you'll need to use.
The 300PSI is affected by the cam timing, if anything, your cams might be out a tooth.
Or to put it another way, when the cams are a tooth "out", the compression number go up.

10 to 1, 400cc per cylinder, combustion chamber = 44.44cc
bore 81mm, 3mm off the head, volume = 15.46cc but it's less than that due to the shape.
lets say 10cc.
That makes 34.44 cc + 400cc = 434.44
434.44/34.44 = 12.6CR.
But that's just guessing.

Going with 15cc difference that's 429.44/29.44= 14.5
So it's nearly a diesel?
Because the face is now 3mm thinner, it's lost a lot of it's strength and you'll have a problem keeping the coolant in.

It'll probably knock, even on 98.

_________________
6G72 mivec Twin TDO5 20Gs up and running.
6G72 mivec bored and stroked to 3.4 litres...Frankenmitsi build
6G74 mivec bored and stroked to 3.9 litres....Frankenmitsi build.
6G75 under construction....4.2 litres bored and stroked.Another Frankenmitsi.


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PostPosted: 16 Oct 2015 21:03 
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Joined: 16 Oct 2015 18:04
Posts: 10
Location: Dunedin
Country: New Zealand
Cam timing is absolutely spot on, doesnt appear to knock as it is at the moment, not sure exactly lengths etc, but valve clearance is fine, any more off and itll touch, i just dont think my ignition timing is set well enough, will i need to advance for higher rpm opperation? Im just looking to get the best top end performance possible


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PostPosted: 16 Oct 2015 21:06 
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Joined: 16 Oct 2015 18:04
Posts: 10
Location: Dunedin
Country: New Zealand
I have gone through 2 standard head gaskets, this metal gasket and ARP head studs seems to be doing the trick, its been on for almost 3 months and i have entered a few events and never had a problem


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PostPosted: 17 Oct 2015 14:37 
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Joined: 04 Jul 2005 13:25
Posts: 1209
Location: Lower Hutt
Country: NZ
OK so I've already answered a question that you haven't yet asked.
You'd really want to go look for a new head?

Actually, going over those figures again, the CR is a bit low because they start off at 11 to 1, not 10 to 1
So with 10cc removed from the head, starting at 40cc, that becomes 30cc= 14.3 CR
with 15cc shaved off, becomes 25cc= 17.0 CR.
Unless I made a huge mistake somewhere?
Maybe the reconditioner only shaved off 1mm but charged you for 3mm?

Those numbers would be far too high for V8 drag cars running on race fuel.

Steve

_________________
6G72 mivec Twin TDO5 20Gs up and running.
6G72 mivec bored and stroked to 3.4 litres...Frankenmitsi build
6G74 mivec bored and stroked to 3.9 litres....Frankenmitsi build.
6G75 under construction....4.2 litres bored and stroked.Another Frankenmitsi.


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 Profile  
 
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