I have just pulled the engine out of my car and have a couple of questions for the more technical/experienced members. Firstly, I was thinking of having the intake manifold polished, has any body had this done or been quoted for it, if so how much?

 

Secondly, is it worth having the heads ported, flowed and polished or is it going to be a waste of time and money?

 

Any advice will be greatly appreciated. top site!

 

Do you mean polishing inside or outside ? Outside has been done. Not sure on insides - over the years I've heard people saying it's good and others saying it's bad - got no idea.

 

Head work on the intake will give benefits on the 300. I know SE do it. Not sure how much you'll get - best bet would be to give them a call.

 

Dave

 

There is the upper intake manifold (plenum) and then the lower intake manifold. Which one do you mean?

 

I think in the sequence of upgrades, polishing of these comes much lower down the list.

 

The porting, polishing and flowing of the cylinder heads is only a real benefit if your going to fit a pair if big turbo's (T28 or GT2530) and a set of high performance cams etc.

 

To make use of turbo's and cams, you'll need forged pistons with titanium rods, very HD clutch or auto gearbox as well as larger injectors, intercoolers, eprom upgrade, exhaust and airfilter!

 

Even after fitting this lot, you would probably only notice the hp gains of porting and polishing when running 10/10 on the track. Maybe Schumacher would notice it when running 14000rpm.

 

If you remove the heads, then it is advisable to skim them, reseat the valves and maybe even change the valve stem seals. While this is being done, you'll probably decide to port and polish at the same time.

 

If you start this way then be prepared to spend.

 

Let us know why you've pulled your engine and maybe we can offer further advice on whatelse to do while it's out.

 

Steve

 

 

 

On the plenum i did mean on the outside purely for cosmetic reasons. I did start polishing it myself but with a black and decker drill this is going to take time and lots of it!

 

The reason I pulled the engine was to convert the car from auto to manual. Some may think it a silly idea but the auto box started to play up and would have cost well over a grand to sort. As i originally wanted a manual it seemed like a good idea to change. While the engine was out i intended to change the turbos as well, which ones i'm not yet sure of so any suggestions are welcome.

 

I was told that the manual box wouldn't take much power and the auto was a better bet. However there was a tt in max power 12 months ago with 600hp and a manual box.Which one is true?

 

Also i need the hydraulic clutch system, anyone know where I can find one?

 

Paul,

 

Polishing the plenum takes somewhere around 19hrs if you have the proper equipment. The end result is worthwhile though!

 

Changing from auto to manual isn't an impossible task and I know that Luke Borg from the Z Center is doing exactly the same thing.

 

The standard auto gearboxes generally don't handle big increases in power because of poor cooling coupled with weak drive clutches and torque converter. Unless your prepared to pay for a level 10 transmission upgrade from the U.S which costs anywhere from £3k upwards, it's best to go with the manual transmission although a HD clutch is a must. IMO I would say that the manual transfers the power more predictably and has less power loss to the wheels so is therefore the better choice.

 

A new wiring harness is a good idea and you can source this from Courtesy Nissan for less than $400. Also you'll need your eprom changed for the manual. It's probably worthwhile upgrading to the JWT eprom at the same time. You will be able to maintain you current auto ecu to use with the manual eprom upgrade.

 

For the hydraulic clutch system you can speak to try Mike Feeney of the Z club on 01277 374201 who normally has lots of Z32 spares in stock. He can also source genuine Nissan parts cheaper than the dealers.

 

As for choice of turbo upgrade, it depends on what type of driving your prefer. I was taken for a spin in a 625hp ZX in the U.S but thought that the initial lag was too much (although he had the nitrous switched off). If you like fast launches off the lights then the stock turbo's are probably best but it you prefer running from 70mph to 150mph very quickly then go for bigger ones. The only problem being that bigger turbo's generally need bigger injectors and intercoolers etc etc.

 

Why not also go for the aluminium propshaft from the U.S?

 

Steve

 

 

 

Pault, although 600bhp is quite possible, don't believe everything you read in that mag. The BHP figures are often a little on the large side, shall we say.

 

I've have to agree with Steve on the turbos, I'm worried of changing to bigger turbos and loosing all the low down fun, which is most of the time. Now, when is someone going to come out with a supra type setup... One big turbo and one small per side and a pressure switch to go between them! I supposed one small turbo per cylinder is a tad excessive huh? MMM, is NOS really not road legal over here? heh heh heh?