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257rwkw - GTS25t with Microtech LT12

whatsisname

By whatsisname,
in Engines & Forced Induction

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whatsisname Grand Master

whatsisname

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Kabab,

Yeah it's been a while since that dyno day hey! Thanks mate :P

Yeah like I posted above, AFAIK they're still stock!? It's "possible" to flow @ least 400hp with them on stock fuel pressure. So with a fair whack of additional pressure it "should" be possible.

I remember using some basic injector sizing calc's that showed the stock 370cc'ers "can" flow enough for ~420hp @ 100% DC, then add the extra pressure on top.

Ahh here it is - A post I made on SDU a while back (contains a quote from Martin) -

"Injector sizing is quite a simple rule of thumb. Divide the injector size (in CC) by 5.2 then multiply it by the # of cylinders. This gives you a 90% duty cycle figure for 40psi of fuel pressure."

So given the stock GTS25t injectors are 370CC / 5.2 X 6 = 426.9HP @ the crank on 40psi fuel press'. Add an adjustable fuel pressure reg & Bosch 600HP pump, bump up the fuel pressure to 50-55+psi, & you've got potential for 400+HP & duty cycle to spare.

Now bump the pressure to 60-65+psi & so on & so on....

The big factor in most cases is the fuel pump isn't able to maintain pressure under the extra load.

The Gibson Motorsport GRP A GT-R's ran up to 138psi fuel pressure through Nismo 550's!!! . They used a very impressive supply system to cope (twin systems + a mechanical pump).

Guest MFX_R33

Guest MFX_R33

Posted
Posted

I have a similar problem with tune at the moment. Every time I take off I leave the opposition in a cloud of black smoke (I still leave them though). The car is running way too rich and is staining my rear bar.

I think with some more tuning and knocking down the A/F R I can see some more power.

As far as injectors go I am running 205rwkw with stock injectors AND stock pressure, and the are still coping (if not close to 100%).

Be good to see how you go on the track (I see you have a similar theory to me, run it on the track as it is on the street).

Jeff.

matlowth Proficient

matlowth

Posted
Posted

Good good good! :P

From the sounds of that then, I should be right with my 550's anyways :D

matt

Originally posted by whatsisname

Kabab,

           Yeah it's been a while since that dyno day hey! Thanks mate :D

Yeah like I posted above, AFAIK they're still stock!?  It's "possible" to flow @ least 400hp with them on stock fuel pressure. So with a fair whack of additional pressure it "should" be possible.  

I remember using some basic injector sizing calc's that showed the stock 370cc'ers "can" flow enough for ~420hp @ 100% DC, then add the extra pressure on top.  

Ahh here it is -  A post I made on SDU a while back (contains a quote from Martin) -

"Injector sizing is quite a simple rule of thumb. Divide the injector size (in CC) by 5.2 then multiply it by the # of cylinders. This gives you a 90% duty cycle figure for 40psi of fuel pressure."  

So given the stock GTS25t injectors are 370CC / 5.2 X 6 = 426.9HP @ the crank on 40psi fuel press'. Add an adjustable fuel pressure reg & Bosch 600HP pump, bump up the fuel pressure to 50-55+psi, & you've got potential for 400+HP & duty cycle to spare.

Now bump the pressure to 60-65+psi & so on & so on....  

The big factor in most cases is the fuel pump isn't able to maintain pressure under the extra load.  

The Gibson Motorsport GRP A GT-R's ran up to 138psi fuel pressure through Nismo 550's!!! . They used a very impressive supply system to cope (twin systems + a mechanical pump).

whatsisname Grand Master

whatsisname

Posted
  • Author
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Jeff,

We had a good old chat @ this years Adelaide Autosalon :wavey: Once you've got your tuning sorted you'll be laughing. You've got all the hardware, its just power there for the taking! It's also one very nice looking car mate!

I'm all for quick (drag) times, records made to be broken & so on, but I like the idea of knowing what a car can do as is, all day, every day. AIR is set to start street meets this coming weekend (Nov 2-3) but the Extreme Horsepower show is on so I'll wait till a later meet.

Matt,

See how you go with the 550's mate, if they can flow the horsepower safely your laughing :D It’s nice to have the extra capacity in reserve though I guess.

:P

rev210 Grand Master

rev210

Posted
Posted
Originally posted by whatsisname

Rev',

        I wish I knew the exact specs mate!  I need to see if Vince can recall what specs he requested from PT?  

:lol:  - Ah yes the old cement in the boot trick!

How much did it end up costing for the turbo?

I appreciate its got the T3 flange but was it a straight bolt on?

cheers

:)

whatsisname Grand Master

whatsisname

Posted
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Posted

From memory it was ~$1900 plain bearing (well over 2k BB!) Yeah mate it's a straight bolt-on, but it's a very tight fit! They actually had to grind a small area to ensure clearance on the manifold.

My turbo is the only area I wish I'd gathered more info on :) At the time I just asked for a turbo that could make good power without huge boost levels. I was prepared to accept a little extra lag to keep the cost down.

When Vince showed me the size difference btw my old turbo & the new one (total size & wheel/housing size) the new one was quite a bit larger. Certainly larger than a high flowed standard turbo. No chance of the original heat shield fitting back on :)

whatsisname Grand Master

whatsisname

Posted
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Posted

Sim,

G'day mate! Ya' can never have too much ;)

A ride in the pram spins out the new addition so she must be blown away by a ride in Skyline! :lol:

I'll drop you a line no prob's mate. As you'd know I don't go on ICQ @ all these days, it stuffed up & I've been too lazy to suss it out ;)

HKS GT3040 @ 2.0bar "Holy smokes Batman":eek:

Azlan,

No mate the BOV replacement wasn't to improve performance. Hmmm, actually it was & it wasn't.

My stock BOV never leaked (@ 13-14psi it shouldn't either!) but it did have trouble discharging the pressure on closed throttle. In short it wasn't able to dump all the air & therefore caused compressor surge. So on went the GFB "Basic", which actually flows 93.6 CFM compared to the Mach 1/Plumb Back - 54.5, Hybrid/Bovus Maximus - 80.1 & the Mach 2 - 53.3. The Basic is the quietest of this bunch too, less restriction ='s less psshhhhhht (something I prefer). It's also the cheapest! My guess is noise levels sell BOV's :P

The fact that it's a vent to atmo BOV is only due to it's superior flow capabilities, & having a MAP based ECU. Defectable for sure but then so are lots of things!

Unless the factory BOV isn't doing its job then I can't see any performance gain in replacing it. It was working fine in my case, it just couldn't dump enough air.

:)

Matt

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