Just to start with can we stick to combined pressure or it just gets confusing.

 

So is 20-22psi ok on stock setup?

 

Because in a few weeks that's what I'll have. I've done my research and most say that after 28psi you need to seriously start thinking about internals.

 

So I thought a 3-4 psi increase each turbo wasn't over the top. But should give me that little extra kick. And I was just wondering what other people where running.

 

Before anyone asks one of my turbos is shot and while I was changing them I thought I might as well do a few mods and get a little more power.

 

I should be getting 400bhp @ flywheel at this pressure . . . if my maths is right :tongue_smilie:

Just found this aparantly reason for not fitting fmic ?? Quite interested as i was toying with the idea of getting one lol

 

 

 

4) With the Apollo or Greddy, there are inherent problems with the "crossflowing" design of those intercoolers. They cross-over the airflow so that it eliminates the balance that Nissan developed into the powerplant. i.e. the driver's turbo is powered by the driver's cylinder banks, however, the driver's turbo feeds air into the passenger cylinder banks (note the design of the upper plenum). This creates a great deal of airflow balance between the two banks of cylinders. By crossing-over the intake tracts, the chance of running one side of the engine dangerously leaner than the other is very high.

 

That doesn't make sense to me, there is still the balance bar equalising the pressure before it hits the individual cylinder chambers. No different than before. Also, that quote is from Mr AshSpec himself as to why he doesn't like FMICs, when promoting his own SMICs. I can't get my head around why there is a chance it will run one side dangerously lean. What is the reason for this chance? What's the probability of it occurring? Why doesn't it do it all the time? How come there are serious high-powered cars running FMICs just fine?

 

I have wondered about the change of design in charge supply though. As with everything, I'll be investigating any disparities between the AFRs from both banks when I get chance.

Very interesting this. I will be changing my turbos in the next few months.

 

No idea what to go for yet but reading this is giving me food for thought.

 

Just going through your PM now :laugh:

That doesn't make sense to me, there is still the balance bar equalising the pressure before it hits the individual cylinder chambers. No different than before. Also, that quote is from Mr AshSpec himself as to why he doesn't like FMICs, when promoting his own SMICs. I can't get my head around why there is a chance it will run one side dangerously lean. What is the reason for this chance? What's the probability of it occurring? Why doesn't it do it all the time? How come there are serious high-powered cars running FMICs just fine?

 

I have wondered about the change of design in charge supply though. As with everything, I'll be investigating any disparities between the AFRs from both banks when I get chance.

 

Dunno I can't really work that part out myself, as you say the balance bars there regardless evening out both plenum pressures :s

The age old SMIC vs FMIC argument = me bored shitless at yet another dose of theoretical internet based urban myth arguments and counter-arguments

 

and in this instance I suspect that it would detract from what has thus far been an extremely interesting and informative topical debate

 

 

 

 

 

 

 

 

 

 

 

*FMIC's must be better because they look hard as nails.....that is all! :tt2:

The age old SMIC vs FMIC argument = me bored shitless at yet another dose of theoretical internet based urban myth arguments and counter-arguments

 

and in this instance I suspect that it would detract from what has thus far been an extremely interesting and informative topical debate

 

 

 

 

 

 

 

 

 

 

 

*FMIC's must be better because they look hard as nails.....that is all! :tt2:

 

 

Not at all bud, as a manufacturer of intercoolers states that fmic's can cause lean conditions I think it's one thing worth clearing up before I go and spend £££ and since th dudes on the subject who better to ask :)

 

Personally I'd prefer to stick to SMIC's :) just better ones :)

With regards to exhaust diameter, it's a bit of a moot point unless you're running decent elbows. Which is a shame, as they're kind of difficult to change.

 

Component design is important to me as optimal choices means easier power and better results (mapping is basically the link between computer programming and mechanical engineering), so I keep a load of papers & books on this subject as I did a lot of research back in the day for Jaguar and then Mercedes Mclaren F1 in camshaft-tappet interaction and Tribology (http://www.ingentaconnect.com/content/maney/imr/2007/00000052/00000003/art00003 & http://oro.open.ac.uk/11240/)

 

According to A. Graham Bell (my go-to guy for this sort of thing :lol:), you're looking at twin 2.5" for a 3L engine with 120-150bhp per litre. After that, go to twin 3-3.5" higher specific outputs. But as with everything, testing on a per-car basis is where the optimum will lie. Personally, I'm a fan of bigger-is-better (even though I continuously disprove that with my difficult-to-tune T78-powered 2L MR2).

 

*FMIC's must be better because they look hard as nails.....that is all!

 

So true, so very true. I'd struggle to find the will to refit SMICs, front end looks menacing :devil2:

Noel given your length of time on this forum (2003) and your low post count,add this to your apparent knowledge of the tuning limits of these cars well my question to you sir is "where the f$£k have you been". Your imput since becoming a trader has been very intresting and long may it continue:yes:

Noel given your length of time on this forum (2003) and your low post count,add this to your apparent knowledge of the tuning limits of these cars well my question to you sir is "where the f$£k have you been". Your imput since becoming a trader has been very intresting and long may it continue:yes:

 

Much appreciated, thank you :blush:

 

Quite ironic really, I joined almost a decade ago to source a Z32 MAF for my S13 which I go on about all the time. Goes to show how long I've been tuning Nissans! Shame it took me so long to buy a Zed!

not really no lol :s

because if im not mistaken an rb for example is still twin turbos and those two down pipes branch into a single 3" exhaust.

where as a vg that down pipe pops into a 2.5" exhaust, on either side.

so each turbo has its own 2.5" exhaust section rather than 2 turbos being forced down one 3" section. maybe im confused. unless you've got fat tubs I wouldn't think youd need 3" either side to efficiently remove the output, and I cant see why in terms of output a single 3" would be better than a pair of 2.5"ones.

 

Ok with exhausts and sizes there is a general rule of thumb to go by providing you have the turbo elbow correct in size as well

 

single and twin turbo cars single exhaust 2.5" is ok to around 200-250 hp after that it proves to have back pressure issues you cant get around and even at this horse power level 3" is preferable but not essential

250-450hp 3" is a must to free up spool and horsepower over 450 hp 3.5" becomes a necessity although a lot of people don't seem to realize when you get to 650-700 + it needs to be 4" even though a lot of the turbos at this level have a 3" discharge on the exhaust housing it necessary to expand it as close to the turbo as possible before bottom of bulkhead to the larger diameter to accommodate the exhaust gas expansion as it cools down as it gets further away from the turbo so as not to create back pressure

 

Twin turbo cars twin exhausts have same issues but you if you look at it logically twin 2.5" is ok to around 400hp twin 3" 5-800hp twin 3.5 900hp and so on just a basic rule of thumb to go by without getting to technical

What manifolds and elbows do you guys favour?

What manifolds and elbows do you guys favour?

id go mike smith, ams or custom manifolds. and

down pipes alloy toys 3 inch for internaly gated turbos custom if external but thats just me :-)

Silverline what the advantages on the split elbows or divorced what ever there called the ones where the exhaust housing and wastegate holes are seperate, to elbows that arnt divorced all the elbows for sale for the zed seem to be divorced but the majority of other cars use the elbows with just the one outlet in the elbow, hope this makes sence lol

i was reading somewhere that the original design spec of the vg utilised the cast iron characteristics of the stock manifold to disapate heat through the block and create a convection currect of heat transfer through the water coolant lines. also tublar ones are prone to cracking so theres two great reasons to only use cast manifolds on the tt.

Silverline what the advantages on the split elbows or divorced what ever there called the ones where the exhaust housing and wastegate holes are seperate, to elbows that arnt divorced all the elbows for sale for the zed seem to be divorced but the majority of other cars use the elbows with just the one outlet in the elbow, hope this makes sence lol

lol yes it does the divorced ones put the wastegate gases. back in at the widest point ie the 3 inch part to reduce the backpressure rathe than earler on as it expands plus in some cases it easier and better flowing to that than oval it all from the turbo not in all but some turbo type dependant. if that makes sense without getting to technical on my phone lol

i was reading somewhere that the original design spec of the vg utilised the cast iron characteristics of the stock manifold to disapate heat through the block and create a convection currect of heat transfer through the water coolant lines. also tublar ones are prone to cracking so theres two great reasons to only use cast manifolds on the tt.

relibilty of cast manifolds is good compared to cheap stainless ones but not any better than a properly built 316 or 321 grade manifold thats built properly and not for the ebay market

the last thing you want is a manifold that disapates heat back into the engine as you want it to retain all the heat in the runners of the manifold this will keep the engine cooler as less transfers back in to it and increase spool of the turbos as the hotter the gas exiting the more can be gotten out as its smaller and the quicker it will spool yout turbos

stainless actually retains the heat naturally in the manifold better than cast or mild steel making it the best option if its built properly and i of course refer to the 200 pound chinese things a pair of good tubular manifolds will cost 5 times that so on a sensible budget the cast ones are a good compromise for flow. and reliability

This is the experience of Greg Dupree with stainless and inconel manifolds:

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2347243/INfo.html

 

With the Z32 the problem of cracking is made worse by the weight of the turbos hanging off the manifolds. SZ stopped

selling inconel manifolds and went with cast iron from Mike Smith.

 

-Andrew

This is the experience of Greg Dupree with stainless and inconel manifolds:

 

http://www.twinturbo.net/nissan/300zx/forums/general/view/2347243/INfo.html

 

With the Z32 the problem of cracking is made worse by the weight of the turbos hanging off the manifolds. SZ stopped

selling inconel manifolds and went with cast iron from Mike Smith.

 

-Andrew

agreed on that statement but when i refered to stainless i meant a set of longer tubular manifold of equal length i should have been clearer with my answer as the longer ones of course dont have the same problem when braced correctly as an un braced short version as you have shown with your link there are lots of variables to a succesful manifiold and i was generalising prehaps a little more than i should have done with my previous reply

Well I have just spent the last I don't know how long reading through this thread and to be honest learnt a bit, but to add my two pennies worth.........i know bugger all! Just wanted to join the fun, im now cross eyed and have a head ache from trying to understand everything lol :tt2:

Well I have just spent the last I don't know how long reading through this thread and to be honest learnt a bit, but to add my two pennies worth.........i know bugger all! Just wanted to join the fun, im now cross eyed and have a head ache from trying to understand everything lol :tt2:

 

All you need to understand is that you need another Z....:tt2:

lol yes it does the divorced ones put the wastegate gases. back in at the widest point ie the 3 inch part to reduce the backpressure rathe than earler on as it expands plus in some cases it easier and better flowing to that than oval it all from the turbo not in all but some turbo type dependant. if that makes sense without getting to technical on my phone lol

 

Ahhh ok yea makes sence so would you say better to have the divorced elbows?

 

I also would agree equal length proper built tubular manifolds are really good as it says with them being equal length it feeds air in to the ports all at the same time as with non equal this doesn't happen as some runners are longer than others

Edited January 8, 201312 yr by 111mattin111

All you need to understand is that you need another Z....:tt2:

 

ah with you now bud, all makes sense lol.....

Ahhh ok yea makes sence so would you say better to have the divorced elbows?

 

I also would agree equal length proper built tubular manifolds are really good as it says with them being equal length it feeds air in to the ports all at the same time as with non equal this doesn't happen as some runners are longer than others

 

Well i havent seen any non divorced ones i like that are on the shelf leaving divorced as the only options

if i was making a set my self i would use a stainless flange with an atp t25 to 3" transition and a 3" elbow and v band for the best flow that way its 3" start to finish but again thats just me and what i will be doing :)

 

with tubular manifolds its actually the other way round the idea of equal length is that you get a constant pulse fire to spool the turbo faster so a constant flow of gas from each bank just as example 123 123 123 where as a cast log isnt so you could in theory get 12and 3 arrive at once then a gap of no gas followed by 12 and 3 again hence equal length being far more responsive :)

Cheers for the advice oh got that wrong then lol, I've got the hks supper dragger I'm going to take out the massive silencer and get that as free flowing as possible then I might have some 3in elbows and down pipes made if not will order some

Cheers for the advice oh got that wrong then lol, I've got the hks supper dragger I'm going to take out the massive silencer and get that as free flowing as possible then I might have some 3in elbows and down pipes made if not will order some

The Dragger is 3.5" at the back half so its perfect its the middle silencer you need to eliminate where it goes 2 into 1 which is quite tricky to fabricate silencer wise so a y pipe would be the solution in that section the front pipes will be 2.5" if you have the full turbo back system.

its very well made and designed if only they had built it in stainless lol

Yea such a shame it's not stainless, yea ill be taking the big silencer out and have a y section put in should sound alot nicer aswell with that huge silencer taken out, I've also got an apexi n1 backbox I was thinking of using the dragger as a template to make a stainless system to connect the n1 to the I'd have a choice of exhaust

 

Think I'm gonna order some of these then make my own 3in elbows :)

http://www.atpturbo.com/mm5/merchant.mvc?Screen=PROD&Store_Code=tp&Product_Code=ATP-FLS-023&Category_Code=

Edited January 8, 201312 yr by 111mattin111