as above. set on the bay and was thinking of buying them for my twin turbo but he doesn't now if they will be suitable.

 

sorry for posting again

I'm not 100% sure Derek - I'd have thought that, owing to the lower compression ratio of the TT against the NA; the heads would certainly be different somehow....

 

Richard

Heads are the same iirc, but the cams and valves are different, im sure one of our engine gurus will be able to give you the definitive answer :thumbup1:

I'm not 100% sure Derek - I'd have thought that, owing to the lower compression ratio of the TT against the NA; the heads would certainly be different somehow....

 

Richard

 

In the case of the Z32, lower compression is achieved by having pistons who's head has a more shallow crown. The combustion area on the head is the same, pistons have less clearance on an NA when at TDC thus giving it a higher compression ratio.

there is a slightly better flow on the n/a heads and they have a different part number both are of course interchangable

turbo exhaust valves are harder than the NA too.

as above. set on the bay and was thinking of buying them for my twin turbo but he doesn't now if they will be suitable.

 

sorry for posting again[/QU

 

The inlet ports are different and the exhaust studs need to be removed and refitted in the TT exhaust manifold configuration and as said before the TT exhaust valves are inconel. I know this for sure as I have both na and tt heads in my garage.

As for use on a tt I cannot confirm.

Valves are the Main difference ( softer metals )

Cams are all most identical to Auto cams ( Opening time duration )

 

or tho they can/have be used in turbo applications but only around to 5>7psi

 

Compression on the vg30de engine is done by the piston having a larger/higher crown

99% sure the Cylinder had bowl is the same

Valves are the Main difference ( softer metals )

Cams are all most identical to Auto cams ( Opening time duration )

 

or tho they can/have be used in turbo applications but only around to 5>7psi

 

Compression on the vg30de engine is done by the piston having a larger/higher crown

99% sure the Cylinder had bowl is the same

 

 

any particular reason why 5-7 psi mark ?

I assume he's regfering to the exhaust valves, as the heat increases here as Psi increases? Yeah? It reads that the cams arn't suitable though to me.

The cams will be fine if mapped correctly as will the valves just because they arnt inconel dosen't mean they will burn out as heat only increases in a bad way if it is running lean or has vey bad retarded timing so just wondered why only 5-7 psi as i cant see any reason for that with an n/a cylinder head

Steve only going by what the Yanks have been doing with the NA engines over there on the specs before the engine went pop ...

but saying that they was using complete engines

 

but like u and i know most of it is heresay but i'm not going to tell ppl on here that u can run up to 20psi boost on the heads and have them fail

the comeback wouldnt be good would it ?

 

Mark

 

 

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Just being safe in what i say and dont want to mislead anyone in to thinking something

Edited February 1, 201411 yr by MarkDerby

Steve only going by what the Yanks have been doing with the NA engines over there on the specs before the engine went pop ...

but saying that they was using complete engines

 

but like u and i know most of it is heresay but i'm not going to tell ppl on here that u can run up to 20psi boost on the heads and have them fail

the comeback wouldnt be good would it ?

 

Mark

 

 

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Just being safe in what i say and dont want to mislead anyone in to thinking something

 

so your prognosis was based on heresay from what you have read on american websites using n/a engines and not on the head design

 

so just to clear this up as i hate people to read anything thats open to being misleading

 

the head will in good condition be fine any comparable boost levels used in uprated conditions

the valves will also be fine as if mapped correctly they will not melt

the cams only alter the power band and where its produced and amount of air and fuel allowed in with size of lobe so when mapped correctly can be used at any boost level only rpm is restricted here

valve springs limit rpm by strength to hold the valve at its given rpm so with stock cams not an issue here again

valve buckets are the same and if good will also be fine as long as oil is 10/40 or below so the oil is not to thick ie 10/50 as it will cause valve float on rev limiter

i dont think i have missed any components out if so please let me know

so on that basis if any one wishes to use n/a heads in a turbo yes it will be fine if mapped correctly if running the stock ecu Noz will be the man do do this for you and feel free to upgrade your valves springs cams and valves and it will only be better

if anyone would like further information please feel free to give me a pm for any advice only happy to help club member's get the best information i can give them

i was reffering to Boost nothing more

i was reffering to Boost nothing more

 

the boost wont affect the head though if it is in good condtion dosnet matter if it's 5 or 25 psi thead is still capable of running in those condtions the only limiting factor to it making power is cam size and duration in technical terms and that will not be an issue unless you are looking for big power in which case be it a turbo or non turbo head you would need to upgrade these components

Some top quality info there from a professional. Cheers for clarifying there Steve, I'm guessing the inconnel helps with longevity rather than outright functionality?

Some top quality info there from a professional. Cheers for clarifying there Steve, I'm guessing the inconnel helps with longevity rather than outright functionality?

thank you sir

yes you are correct it will help with longevity not function as the valve can take a beating under certain conditions

just a small addition, keep an eye on the casting stamp on the side of the heads.

if you are replacing 40P TT heads with NA heads on a TT block, verify the casting stamp on the NA heads is 30P and not 10Y (which is later style and your lower intake will not fit).

 

if you have 48P stamped TT heads (later style) I would strongly recommend against replacing these with (10Y) NA heads