Thought I should move this from the 'Journal' forum and update where the project is at. Wish I was at Coventry with everyone, but these things always take longer than anticipated, lol

 

20/01/2013

Having had the car for a few years now I have finally given in to the urge for more power.

 

The original engine in the car runs superbly only 66k miles with a proven Dyno run @ 357bhp, with boost jets and a uprated chip & air filter. Not bad at all for a 300ZX, but I was bitten by the bug and was set on going for more bhp and reliability, (I know why fiddle with it if it ain't broke). But having been lucky enough to have many nice high powered cars in recent years I wanted to keep the Zed long term and the engine is the first part of the project so it need's to be a good strong/reliable build.

 

After looking at various options of buying a part built engine form the US I decide to also keep my eyes peeled for the poteintial of purchasing an uncompleted project rebuild.

 

Back in March/April 2012 an ebay listing caught my eye regarding a nearly completed forged engine rebuild. The only problem with it was that the rebuild wasn't exactly completed by the most reputable of Zed engine builders known within the Zed world. In fact the seller had been caught up in horrific events where parts when missing, work was never finished and finally the garage was broken into and his engine was stolen. Retrieved from a nearby field 24 hours after going "missing". see here for a bit more http://www.300zx.co.uk/forums/showth...light=s+mochan

After talking with the seller for sometime we struck a deal and I waited for the day when the pallet with the engine would arrive.

 

It came with forged internals, Wiseco pistons, Eagle rods, ACL Duralite white metal bearings ARP main con rods and head bolts, Tomie 260 degree camshafts with solid lifters & harder springs, SARD 850cc injectors with a Border fuel rails/ new Turbo's, s/steel manifolds, new oil pump, heads polished, exhausts ports and valves shimed & lapped.

 

Didn't look all that great mind when it finally arrived to be honest, and I still had my doubts as to whether I had done the right thing in buying this.

 

 

 

After stripping down the engine as far I was prepared to take it anyway,

 

 

 

 

 

I wasn't going to attempt to go much further, so I thought it would be best to get this done properly!

 

So a call was made to Jim @ PowerZed to arrange a date to get everything to him in order for him to work his magic.

They do do it. Whilst it's not listed, they can get it pretty easily. Tomei was a Platinum sponsor of ZNationals (I sat on the same VIP table as the president of Tomei) - both Z1 and Tomei have a great relationship. Speak to Jon or Chuck and they'll be able to get it.

 

- - - Updated - - -

 

 

 

:rofl: ;)

 

Good to know thanks Si.

 

Bloody predictive txt, lol

Indeed, the stock headgaskets are perfectly good for high power levels.

 

What power levels have you seen these used up to?

 

I've frequently heard the Cometics are suitable for more than one use, can the stock or Tomei be used again?

Most metal HGs can be used again. Stock HGs can take quite a beating - plenty in the US running 400-500hp. Howard's will be running 600hp plus.

Stock HGs can take quite a beating - plenty in the US running 400-500hp.

 

And the rest:

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2217574/I-use-stock-head-gaskets-and-stock-head-bolts.html

And the rest:

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2217574/I-use-stock-head-gaskets-and-stock-head-bolts.html

 

Interesting, thanks Andrew.

 

Added the link from TT.net

 

Posted by Greg D. (Specialty-Z) on November 03, 2008 at 7:48 PM

This message has been viewed 201 times.

 

In Reply To OEM or Cometic medal head gaskets??? posted by LivinTheDream on November 03, 2008 at 05:50 PM

 

Message I have stock gaskets and bolts on my own Z as well as all the builds we have ever done and we have never had a gasket issue ever.

The stock gaskets and bolts will hold 1200 HP easy.

The only reason you will have a issue with stock gaskets is detonation or overheating. The cyl pressures with detonation is insane and with hard detonation I do not think any gasket or bolt will hold and if it does much other damage will result.

Octane and tuning are key!

 

Seems like I would have to ditch my current heads to run OEM gaskets as they have already been skimmed:taz:

Edited October 18, 201411 yr by bigh
Added info

Seems like I would have to ditch my current heads to run OEM gaskets as they have already been skimmed:taz:

 

Not necessarily, but would need mapping to suit.

All very disappointing!

 

When I first bought the Zed, the conversations for build on here were all about Wiseco, Eagle, ARP, Cometic etc. so having built up the said various components for a build it now seems that few, if any are now needed for 400hp + and even in some cases not now recommended!!

 

Oh well! too late to change now.

Don't take things that way Steve, whilst you can hit 400hp with a mostly stock setup there is nothing wrong with an over speced engine, equally the equipment you would have used to 400 should now net you more, that's a good thing. It's only the HG that people are questioning, and as Jaffa pointed out he has that very gasket without issue. You could replace them with stock without too much expense if you were concerned about it.

Cheers Stephen, just always feel a bit behind the game with this Zed business, Lol!

Totally agree with Stephen. You're every bit as right to up-spec components when doing a rebuild regardless of power.

Plus aren't the Eagles and Wisecos lighter than the stock gear anyway?

Cheers Stephen, just always feel a bit behind the game with this Zed business, Lol!

 

I wasn't aware it was a race bud, just a fun journey :D

Plus aren't the Eagles and Wisecos lighter than the stock gear anyway?

 

Unsure. Stock pistons potentially are lighter as they're cast (less dense) than forged, however forged are likely to have less material as they're stronger. I'm sure someone on here has measured them.

 

Stock rods and bottom ends are forged and are quite happy to hold 700hp.

Edited October 19, 201411 yr by Funkysi
Schoolboy error!

Stock rods and bottom ends are cast and are quite happy to hold 700hp.

 

Are forged.

Stock rods etc are forged are they not it's just the piston that's cast? The weiscos I think are heavier as they are more dense and there's more material this keeps things cooler and helps reduce the risk of detonation as I understand it.

Error! They are indeed!

Don't take things that way Steve, whilst you can hit 400hp with a mostly stock setup there is nothing wrong with an over speced engine, equally the equipment you would have used to 400 should now net you more, that's a good thing. It's only the HG that people are questioning, and as Jaffa pointed out he has that very gasket without issue. You could replace them with stock without too much expense if you were concerned about it.

 

But isn't it nice to know that you don't need to "over spec" given that the stock engine is already "over spec'd" from the factory

for quite sizeable increases in reliable power with the correct tuning?

Bloody right! The fact that a stock long block z32 broke into the 9s in America less than a fortnight ago is testimony to it's strength, as is the fact that I drove around an NA block running 9psi without a map to suit for 4+ years! Refreshing them with a rebuild like this is nothing but common sense and giving yourself some protection is prudent.

To summarise the above:

 

• stock will take the power (if in good condition and well mapped)
  
• Stock pistons are cast, rods are forged
  
• Aftermarket forged pistons & rods are significantly lighter than stock items
  
• Cometic gaskets seem to be hit and miss, we've now seen a few failures. If you have one fitted and it;s survived to date then it'll most likely be fine!
  
• Stock HG would be my recommendation for future builds, tomei for extreme builds
  

To summarise the above:

 

• stock will take the power (if in good condition and well mapped)
  
• Stock pistons are cast, rods are forged
  
• Aftermarket forged pistons & rods are significantly lighter than stock items
  
• Cometic gaskets seem to be hit and miss, we've now seen a few failures. If you have one fitted and it;s survived to date then it'll most likely be fine!
  
• Stock HG would be my recommendation for future builds, tomei for extreme builds
  

 

 

Thanks Jaffa, good summary

Bloody right! The fact that a stock long block z32 broke into the 9s in America less than a fortnight ago is testimony to it's strength, as is the fact that I drove around an NA block running 9psi without a map to suit for 4+ years! Refreshing them with a rebuild like this is nothing but common sense and giving yourself some protection is prudent.

 

With regards to completely bone-stock NA Nissan engines with a turbo strapped to them, here is one I mapped last night completely from scratch on a £40 SR20DE engine:

 

 

 

Not bad at stock actuator pressure of 0.55bar on a T28H. Completely maxed out the Almera MAF at 309bhp & 297lb·ft. Fun car, quite a handful for me on the dyno.

 

I'm looking forward to some VG30DE-T builds in the future, who's game? Howard, your car was immense. You will love it when you get your hands on it. Might need better brakes...

 

Willy-waving hijack over. Sorry :wack:

Thought I would share some more information that I have received recently from Greg Dupree.

 

I asked him for his thoughts and experiences on OEM and Cometic gaskets.

Below are his comments:

 

Hi Howard,

 

The OEM head gaskets seal the best, I run stock head gaskets on my 1000 HP

drag Z.

We also do all our builds with OEM gaskets.

We have never had a gasket failure with factory gaskets.

 

The only reason to go metal is for bore sizes over 88mm, or if the heads and

block have been surfaced too far.

 

Cometic gaskets are the worst available, I know lots of people that have had

issues with those gaskets.

Tomei are the best Metal gaskets, but it requires an extremely fine surface

that most machine shops are not capable of providing.

Most surfacing machines cut too coarse, they will still seal fine with a OEM

gasket.

 

Hope that helps

Greg

 

I then asked Greg what specification the heads in his opinion would need to be finished to (RA Rough average) if using metal gaskets like The Tomei set.

 

Gregg, Regarding the fine surface finish for the Tomei gaskets, do you happen to

know what RA grade of finish would be required to obtain a adequate seal?

 

I recommend factory gaskets, but the few large bore we have used Tomei metal

gaskets on, we did a 10 Micro inches RA.

Typically the recommended RA is 20-30 micro inches, but smoother = better.

Again, the equipment required for the ultra-smooth surfaces is not found in

most machine shops.

 

Interesting stuff eh? Well I have tried to find a machine shop that can carry out a finish of a 10-20RA and as yet haven't found one and I have phoned over 12 now! Some of them didn't even know what an RA finish was, which i found scary to say the least. So if you are thinking of going to using Tomei then find a machine shop first, and a good one at that. Oh and if you do find one make sure you let

us all know, lol, as they potentially could get a lot of business from future builds.

 

So as it stands at the moment I will be going for a set of new TT heads and OEM gaskets as this seems to be the most reliable and trusted set up even for high powered cars.

Edited October 25, 201411 yr by bigh
Info

I've known all that for a long, long time. I think that would have been a step too far after the "VG30DETT can only handle 370bhp" mythbusting!

 

http://www.sxoc.com/vbb/showthread.php?366339-mhg-or-wire-rung-block&p=4167925&viewfull=1#post4167925

I think the Cometic MHG in my S13 is leaking...

 

It's scandalous that the companies continue to sell the items they describe as not fit for purpose :censored:

I've known all that for a long, long time. I think that would have been a step too far after the "VG30DETT can only handle 370bhp" mythbusting!

 

http://www.sxoc.com/vbb/showthread.php?366339-mhg-or-wire-rung-block&p=4167925&viewfull=1#post4167925

 

 

It's scandalous that the companies continue to sell the items they describe as not fit for purpose :censored:

 

Interesting read Noel, thanks

Effectively the surface needs to be ground rather then just milled to achieve that finish.