Has anyone come across head gaskets for the VQ that we can lower the compression with? I know they are common with many Honda applications.

 

No, I couldn't find any. Had to get one made.

 

yea this would be a good step, a set of some oversized MHG's and some nice ARP headbolts, we could lower compression to around 8.5, we could probably get close to 500RWHP with a nice TT setup, anybody know how much power the trans can hold ?

 

Ravaz,

Where did you get yours made??? I am assuming a thicker copper gasket was what you went with.

 

you want to lower compression nearly 2 full points with a headgasket?! wow. good luck with that.

also keep in mind that you're looking at cylinder shifting under boost due to the open deck design.

 

Before you go doing something like that, you also need to ensure there's enough play in the timing chains. I haven't looked at the 350Z setup, so it might have a self adjusting chain, but I'm not sure.

 

I wasn't aware the VG engine was open deck, does anybody make sleeves for them ? What would you do to ensure the engine could stand high HP figures reliably ?

 

I believe Ravaz has his block at AEBS right now for the full sleeve and deck process. Apparently they can do it...I know they do a ton of Honda's with open deck blocks.

 

I'm pretty sure the VG (from the 300ZX) was closed deck.

The VQ (VQ35DE) in the 350Z is open deck. The best way to ensure engine reliability in high-power applications is to sleeve the block. AEBS is doing ravaz's block, but I'm sure you could also talk to Golden Eagle or Darton, among others. Darton has a modular-integrated-deck (MID) option which seems ideal for our setup. When I can get a little cash in hand and a spare VQ from a wrecked car, I intend to send it off to one of these places to get it sleeved.

 

What evidence is there that we need to sleeve the block though? Truth be told, it depends on the setup. We have seen Subaru motors make upwards of 400 hp at the wheels on an open deck motor (ala WRX).

I'm not saying closing the dekc is not without merit, but lets not make it into a "must have" mod when it has not proven itself to be needed yet.

2 full points with a headgasket is nuts - that is old old old school mentality, and not a good idea to do at all.

 

At what power level do you guys see this as being necessary?

 

I don't know if anyone can answer that yet - time will tell

I also would not recommend a copper unit for a street car either, but thats just me...your results may vary

 

I agree 100%. The only reason I'm a huge proponent of sleeves is because I want at least 500 RWHP (probably more). At that level, I really don't trust the open deck. For people shooting for 400 RWHP max, it probably isn't a "must-have," although I disagree with the 7psi at 10.3:1 CR idea.. It's just asking for detonation issues, which we've already seen on ATI SC'ed cars with poor tuning.

 

Good to se some of us are on the same page then - sensible mods, sensibly done = happy customer. Out of their league mods done on the cheap = giant planter/heavy paperweight

I wouldn't trust anything with 10.3 compression and any amount of boost to get me from A-B everyday without incident, but that's just me

 

I sent my block to AEBS to get sleeved and a solid deck. Why? Well honestly, cyl 6 sleeve was screwed up from the blown piston, and ate up alot of it and we couldn't do anything with it. So instead of me spending ~1400.00 with Nissan for a new block, I decided that being it's only the sleeve and the block itself is fine, I'll just get it sleeved at AEBS and decked. I spent ~400 more sending it to AEBS to get this done, then I would buying a bare block from Nissan. Wouldn't you? I won't mention what my goal is for me putting down, either way I think it was a good choice.

 

I think you're one of about 5 or 6 sane people I've seen on this forum (ravaz as well). Everyone and their brother wants to strap a blower (or turbos) onto their Z and thinks it's going to be reliable, just because a big company (ATI, Stillen, etc) put their name on the product. The problem is, few (if any) of these people know what FI really means, aside from the horsepower increase.

 

I guess I'm insane, oh well.

 

I'm not saying you're insane.. just more or less showing my agreement that I don't trust the VQ under boost.

At least you've shown (repeatedly) that you are knowledgable of engine technology, forced induction, etc, and you're well aware of the consequences of strapping a blower onto this motor. You're apparently willing to accept these risks, and that's fine.. I just know there are lots of other people around here clamoring for SCs and TT kits that aren't aware of the issues surrounding a blown/boosted motor, and will be very surprised (and upset) when their engine pops due to mediocre tuning and detonation.

 

Agreed, I guess I should've put the face after my comment.

There are a lot of people who really should research FI more before doing it. It will make you both more confident and more worried simultaneously when installing FI on your car. Sometimes, I think ignorance is bliss, but that's only until something blows and you're left standing there holding the bag (or engine parts as the case may be).

 

Why not copper headgaskets on a street engine????