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Discussion Starter #1
Hi Guys

What if the respective maximum boost pressures for the Series 1 RB25 turbo if the Series 2 one is 0.85bar.

I am now pretty certain mine is a series 1 turbo on a series 2 car. So far its made 330ish @ 1bar and 1.2 bar made no difference in power. Must have been reaching its limits i guess!

This was only on a quick set up with my new spec, power fc, injectors, fuel pump etc.
 
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If you are running a standard turbo at 1.2bar , don't expect it to live a long and happy life!

Technically, the maximum limits of the standard turbos are 0.9bar - however, I wouldn't run above 0.85 bar and to be on the safe side....0.8 bar.
 

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Discussion Starter #3
Is that for both the S1 and S2 turbos?

I know when we had a look at it it looked as though it was steel internals?
 

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Discussion Starter #4
Also

Bearing in mind that ive got this spec:

Apexi Power FC
Nismo 555cc's
Walbro 255lph fuel pump
Greddy Profec B
Modified turbo elbow with screamer
Kakimoto down pipe
Kakimoto full system
Big FMIC

What is the best value for money turbo / reliable I can get next for 380+bhp.

And what are the costs?

Has anyone had any experience importing turbos from Nengun.com?

Thanks!
 

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Discussion Starter #5
If you are running a standard turbo at 1.2bar , don't expect it to live a long and happy life!

Technically, the maximum limits of the standard turbos are 0.9bar - however, I wouldn't run above 0.85 bar and to be on the safe side....0.8 bar.
I am planning to run it at 0.8 day to day and 1.0 on the odd occasion, this being said I am likely to upgrade the turbo pretty soon!
 
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Also

Bearing in mind that ive got this spec:

Apexi Power FC
Nismo 555cc's
Walbro 255lph fuel pump
Greddy Profec B
Modified turbo elbow with screamer
Kakimoto down pipe
Kakimoto full system
Big FMIC

What is the best value for money turbo / reliable I can get next for 380+bhp.

And what are the costs?

Has anyone had any experience importing turbos from Nengun.com?

Thanks!

Really doesn't matter what spec you are running, it doesn't change the maximum parameters of the standard tubby. If you run above 0.85 bar consistently you WILL shorten the life of your turbo. It may go tomorrow or it may go a year from now.....do you feel lucky?
 
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Is that for both the S1 and S2 turbos?

I know when we had a look at it it looked as though it was steel internals?
Looked as though or is? if the turbo has been uprated and definately has steel internals.....groovy, you will be fine for 1.2bar - anything above that and your going to need a new headgasket
 

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Really doesn't matter what spec you are running, it doesn't change the maximum parameters of the standard tubby. If you run above 0.85 bar consistently you WILL shorten the life of your turbo. It may go tomorrow or it may go a year from now.....do you feel lucky?


it does actually....

what matters is the turbine speed of the turbo and this is also dictated by (as well as boost pressure) what cams are fitted, what RPM the engine is taken to etc, the maximum torque shear the ceramic assembly will take is also dictated by duty cycles and EGT

regards, brian
 

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Discussion Starter #10
Looked as though or is? if the turbo has been uprated and definately has steel internals.....groovy, you will be fine for 1.2bar - anything above that and your going to need a new headgasket
Dont know for certain yet mate, only spoke on the phone breifly to the tuners.

I sent them a picture like the one on ebay of the £799 turbo, where you can see the standard turbo next to a rebuilt/reprofilled one and he said it looks very similar to the rebuilt one.

This car has had a turbo change already in the last two years, I just dont know what was put on then! arghh

will this turbo fit the standard manifold? Is it too small for a 6 cyl car?

http://www.atpturbo.com/Merchant2/m...OD&Product_Code=GRT-TBO-003&Category_Code=GRT
 
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I was led to believe that a turbo had a maximum tolerance, and no matter what else you did, that tolerance could not be exceeded - or at least, if that tolerance is exceeded it would dramatically reduce the life of the turbo. Are you saying thats wrong, cos I'd be interested in leraning why that is.
 

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what im saying stu is that its not directly dictated by boost, its dictated by the turbine speed of the compressor (the part of the turbo that is ceramic)

a cammed engine will consume more air per revolution...larger lift and longer duration means more air getting into the cylinder so more air has to be supplied by the turbo...it has to work harder so this will mean a lower threshold!
(lets remember here that boost pressure is simply a measurement of how much air is not* being consumed by the engine so to achieve the same boost level when more air is consumed is being stressed more)


personally my own engine i use above the limit of 1 bar....because the same turbine speed is reached at the levels i use

[email protected], same turbine speed as [email protected]

so you can go over the threashold with only 0.85bar boost or under the threshold at 1 bar, it depends on spec (in these cases volumetrics and rpm's)


i believe duty cycles are underestimated also....

ill add a link that i hope can explain it better than i have lol

regards, brian
 
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I kind of understood that, but theres blood coming out my ears so I'm going to have a lie down!
 

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Excellant reading (especially off the link).

It just goes to show the correct set up, cams etc, can make such a big differance on low-ish boost.

Ive got a steel internal standard turbo t3/t4 spec garrett and getting it mapped with 555cc injectors and z32 afm with a greddy emanage blue.

Hope its Whoooooosh :dogpile:

yep, i have found it interesting but then i love it when it goes against the flow...

the other two subjects that seem to be very misunderstood on the skyline forums is the 1.2 bar boost limit on the head gasket and decatted cars running richer....i really dont know why people have these opinions:apint:

regards, brian
 

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the other two subjects that seem to be very misunderstood on the skyline forums is the 1.2 bar boost limit on the head gasket and decatted cars running richer....i really dont know why people have these opinions:apint:

regards, brian
brian dont stop explaining here, i'm all ears m8
 

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ok well the amount of power the head gaskett can take is due to cylinder pressure not boost pressure

more power = bigger cylinder pressures so we could have a larger turbo and blow the gasket at under 0.8 bar or run the stock turbo at 1.6 bar (double the boost pressure) but only make half of the cylinder pressure as the previous example

as for decatted cars running richer....why?, its a piece of exhaust for christs sake, it has no bearing on fuel injection IMO on any car (unless i am missing the obvious?)
 
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