Following in from my thread of porting and polishing the heads I have found this on another site,

 

http://www.twinturbo.net/nissan/300zx/forums/main/view/1113689/VG30DETT-Cylinder-Head-Porting-Observations.html

 

 

I'm trying to find a did difinitive answer for my build and have not got any conclusive answers. Which is a shame!

 

 

I'm planning on boring out to 87.5 mm with wiseco pistions,

Open up water galleries,

Replace all seals gaskets etc

Acl race main and big end bearings

Refurbish the heads (3 angle valve cut, currently undecided in port and polish hence this thread)

Stock auto turbo rebuild to inc 360 deg bearings and step gap seals.

Currently stock exhaust manifolds

Possible upgrade to subaru series 2 555 injectors

Os giken twin plate cluch

Full unorthodox pulley set.

large side mount ic's

 

 

I'm not chasing HP but want a streetable responsive tt which I can use for fun no track days or bragging rights in the pub, just need it to please me which it done before loosing compression.

 

Ideally I would like noël to map it as I currently run a mines ecu at 14 psi boost. ( not sure it's suitable)

 

I'm going to decat and convert to manual while I'm at it.

Am I unreasonable to aim for 350-400 HP? With the torque to please?

Edited October 4, 201411 yr by hellraiser

Your power goals are easily achievable, add some cast manifolds while the engine is out, they're not expensive and will let the engine breath

Thank james. Im glad that's achievable, what's your opinion on porting the heads? Is gasket matching the way to go or just remove the flashing/ casting lines. Also I know not to polish the intake ports but the exhaust ports can be polished.

 

Should you you leave a step in the ports between the head and the manifolds or is that only for na engines?

 

So many questions lol

Personally unless you're going with bigger cams and valves I wouldn't bother

I found an American thread, about this. From what I read the VG30DETT heads are pretty free flowing being well designed twin cam heads. Porting heads and bigger valves are more beneficial to older engines or those with less RandD such as sohc v8 engines. The exhaust manifold is far more restrictive than the head itself. Il try and find it for you.

Following in from my thread of porting and polishing the heads I have found this on another site,

 

http://www.twinturbo.net/nissan/300zx/forums/main/view/1113689/VG30DETT-Cylinder-Head-Porting-Observations.html

 

 

I'm trying to find a did difinitive answer for my build and have not got any conclusive answers. Which is a shame!

 

 

I'm planning on boring out to 87.5 mm with wiseco pistions,

Open up water galleries,

Replace all seals gaskets etc

Acl race main and big end bearings

Refurbish the heads (3 angle valve cut, currently undecided in port and polish hence this thread)

Stock auto turbo rebuild to inc 360 deg bearings and step gap seals.

Currently stock exhaust manifolds

Possible upgrade to subaru series 2 555 injectors

Os giken twin plate cluch

Full unorthodox pulley set.

large side mount ic's

 

 

I'm not chasing HP but want a streetable responsive tt which I can use for fun no track days or bragging rights in the pub, just need it to please me which it done before loosing compression.

 

Ideally I would like noël to map it as I currently run a mines ecu at 14 psi boost. ( not sure it's suitable)

 

I'm going to decat and convert to manual while I'm at it.

Am I unreasonable to aim for 350-400 HP? With the torque to please?

 

The lower end of the 350-400 bhp range doesn't require anything other than a boost increase & a map, even with cats & stock side mount intercoolers. I would expect that the stock ECU map would run close to 350bhp without too much trouble, but the timing could be a bit too advanced.

 

It's definitely not all about the numbers, but the set up is way over-specced for your power goals. Not in any way a bad thing though, and it gives you plenty of headroom for future upgrades :)

 

What caused the loss of compression?

Hi noel I'm not sure think its rings . Hence why I'm concerned about the map of the mines ecu. I need to do a leak down to confirm if it's top or bottom of the engine that's the problem.

 

1= 162 psi

2= 150

3= 160

4= 128

5=75 (90 with oil added)

6=162

 

car has never over heated.

I want to build the engine stronger to allow for bigger tubs in the future.

When I'm done building it would I be able to buy a running in map from you then get it properly mapped by you once it's run in?

Cylinder 5 at 75psi, increasing to 90psi with oil in the bore will most likely be damaged ringlands, definitely not a valve issue. Did it smoke & breathe heavily? Cylinder 4 doesn't look too clever, but that's a strange value, neither here nor there :wack:

 

There's too much timing on the Mine's ECU, it's not meant for the UK. The only way to safely run with JDM ECUs is to use race fuel or knock the base timing back roughly 10°, which would make it sluggish and thirsty.

 

Sure, I can provide a suitable running in chip when you need one.

Running in? Get the thing built and up to Noz, the mapping process will do any running in needed then it'll be fun time

Were going to do a leak down on it, see where the loss is coming from. It's amusing in a way that both if us have ****ed blocks at the same time on the same cylinder I think as well! Sorry mines cyl 3

It smoked mostly in first start up from that bank. As si and andrewg can confirm from beaulieu when the kids play park dissapeared under a cloud of it. Seems to clear up a lot once warm.

 

jaffa I didn't know I could do that so that's a great bit of info.

 

thanks to everyone so far for there input :-)

Forget the kids play park, your neighbours where gathering their prized possessions and doing a emergency evac when you fired it up last weekend.

Lol, it's so embarrassing ! Nice car shame about the cloud behind it!

Lol well the red arrows do spend a lot of time in bournemouth, we need another red zed with a red smoke trail.

Noz following on from another thread which you mentions running in procedures, would you recommend running in on stock injectors and boost, or can I install the 555's and run in?

Noz following on from another thread which you mentions running in procedures, would you recommend running in on stock injectors and boost, or can I install the 555's and run in?

 

I have provided running in maps for Power Zed built engines for a wide range of fuel injector sizes. In the case of two different cars, I had to go down to Bristol to get them up & running as the injectors were out of spec for what they were supposed to be. Same with Mark Derby's car, but that was for an ECU firmware issue.

 

What injectors do you have?

I have provided running in maps for Power Zed built engines for a wide range of fuel injector sizes. In the case of two different cars, I had to go down to Bristol to get them up & running as the injectors were out of spec for what they were supposed to be. Same with Mark Derby's car, but that was for an ECU firmware issue.

 

What injectors do you have?

I haven't got them yet but was looking at the subaru yellow top phase2 555's

Update.:::

 

Can you tell why I had low compression strangely the the cleaner of the two cylinders was the lowest compression

The scored one is no4 which read 128psi

No 5 which is the clean one read 75psi I'm going to check the head for any valve damage

Mine's ECU?

Mine's ECU?

yes

That is probably why you have low compression. Aftermarket JDM ECUs are not programmed to be used in the UK. Would have been knocking (detonating) loudly I'd expect.

 

How long was it run for?

Too be perfectly honest i never heard any knocking or wierd noises from the engine. The ecu was installed when i bought it back in nov 2012. It did run like a pig when i bought it but i got it running really sweet. It Pulled really well. I think what killed it was a few laps of castle combe in japfest 2013 with that ecu still installed. A few weeks afterwards i notice smoke when it sat idling. Went through all the usual stuff plugs, pcvs etc etc. Till beaulieu 2014 when it dtsrted to smoke really bad..! That brings me up to date

Found my issue with the other cylinder. I have found that my heads were using the early 30 type intake valves. .. can you see the difference... good one on the left lol

Edited February 26, 201510 yr by hellraiser

Or should I say bottom.... damn picture rotation

Have a good set of the superior eg intake valves. The condition camparison is well obvious

Gaz the seats were soft too on the early heads.