411rwhp from stock internals

[GTS-t VSPEC]

The fact that I got 411rwhp isn't of much interest. The fact that I did it on stock internals, stock cams and stock injectors is.

I had been led to believe by a number of people that without cams that I wouldn't be able to flow enough air to make that sort of power, and that I would have run out of injectors long ago. So I thought I would share this with you incase you decided you had to buy them to make decent power.

I'm running a GT30 (500hp) at 17psi. We currently only have 9deg of timing so that the stock pistons don't blow, so even with the current setup and forgies we have a heap more power available.

Hope this of interest to those of us who own whales:D

[sfifteen]

Very nice What does that equate to in flywheel hp and whats your injector duty cycle at 411rwhp?

[AeroGrace]

Originally posted by GTS-t VSPEC

The fact that I did it on stock internals, stock cams and stock injectors

:crazy: very very nice.

very intrigued....especially on the part of using the stock injectors

[tomj]

/me spits out his coffee ...

stock injectors? nice work .... whats the duty cycle like?

[BU5TER]

Originally posted by GTS-t VSPEC

I'm running a GT30 (500hp) at 17psi. We currently only have 9deg of timing so that the stock pistons don't blow, so even with the current setup and forgies we have a heap more power available.

I'm a bit confused from the above quote where you say "so even with the current setup and forgies we have a heap more power"

Does this mean you've got forgies or are planning to add them?

[2rismo]

1/ Are the standard injectors flowed (i.e. have they been opened up to flow more than 380 (or whatever they r supposed to be?))

2/ What are the specs on the GT30?

3/ Yes please

Adrian

[GTS-t VSPEC]

Buster, Meaning that keeping the boost at 17psi and just by increasing the timing we can get another 20+ hp easily. I don't have forgies yet, but as soon as I can afford them they'll be going in:D

2rismo, I'm sure the injectors are standard 370cc, I'm using a Malpassi fuel reg, with about 40psi of fuel pressure.

Injector duty is on about 80%, so I'm hoping to keep the stock injectors a bit longer.

[JH32]

Paul now you have to do another 1/4 mile run so your sig doesn't make you out to be a lousy driver

[BU5TER]

Mate it all sounds good to me whats the power curve like, can you post a dyno sheet for us

[GTS-t VSPEC]

LOL @ JiMiH, I am a lousy driver, but I should be able to manage a 12:D I have a 2-way diff to put i first though.

Buster, I have the dyno sheet in the car, I'll scan it today at work, then post it up.

[Sydneykid]

Hi GTS-t VSPEC, when you say "I'm using a Malpassi fuel reg, with about 40psi of fuel pressure". Is that 40 psi above boost? ie 40 + 17 = 57 psi. Or is it 40 psi total? ie 17 + 23 = 40 psi.

[Sydneykid]

Oh and what sort of fuel were you using?

[GTS-t VSPEC]

Sydneykid, It's 40psi base pressure with no boost, and will obviously rise with the boost. I was running BP 98 with octane booster. Wanted to run Avgas, but didn't get any in time:(

[Sydneykid]

Hmmm 40 psi is only a little above standard, hmmmm.

This is prety simple maths here, 370 cc's per injector, 6 X injectors, 1 firing per 2 crank revolutions, 12 to 1 A/F ratio, 2.5 litres engine capacity at 1.15 bar (17 psi) at 90% engine efficiency. You end up at 370 bhp (+ or - 5%) at 80% duration. The 20% is for acceleration enrichment, ambient conditions, cold run etc

So 411 + (say for losses) 70 = 481 bhp. That's 130% duration.

In order to get the sort of flow we would have to increase the fuel pressure to 60 psi above boost. In your case that would be 77 psi which is 4 psi above the Bosch Motorsport fuel pump maximum. There are other pumps rated higher of course, but hen you start to run into other complications, hoses, clamps, voltage drop etc.

I'm perplexed??????????????

[BU5TER]

Sydneykid do you use a fuel reg on all your cars or is it only needed if the injectors are maxing out?

[R32-GTS]

I am also in shock how it made 411 hp on stock injectors , but i was there to see it smack it down.

[Sydneykid]

Hi Buster, you asked "do you use a fuel reg on all your cars or is it only needed if the injectors are maxing out?"

Adjustable fuel pressure regulators are a bit of a "band aid" really. They are OK to fix a slight problem when budget is a concern (as it generally is). Bottom line, I prefer to get the right size injectors in the first place.

Hope that helps

[Sydneykid]

Hi R32-GTS, it has been my experience that the laws of physics always apply. Whenever I search enough, I can find an answer, and restore my faith in the laws. There is obviously a reason for it, we just need to find it.

This is pretty simple;

either the injectors flow more than 370 cc's

or

the fuel pressure is more than 40 psi above boost

or

the calorific value of the fuel is higher

or

well, let's leave that one............

[Sydneykid]

Hi guys, there are a couple of other clues here....

Simplistically, boost is resistance to air flow. You run higher boost because the engine won't allow the air to flow into and out of the combustion chamber. The GT30 at 1.15 bar is a little under its most efficient ie; a bit below the sweetspot on its compressor map. About 1.3 to 1.5 bar is pretty much right in the middle to achieve its 500 bhp rating. Now 411 rwhp (480'ish bhp) is pretty close to 500.

My experience has been that a standard flowing RB25DET (standard cams, ports, inlet manifold etc) with a "perfect" intercooler and exhaust manifold, needs 1.4 to 1.5 bar to overcome these standard restrictions to air flow to make 450 bhp. Reducing the restriction (longer duration, higher lift cams and port work being the main ones) you can get 450 bhp at lower boost levels (1.1 to 1.3 bar).

To make close to 500 bhp, I would have to run 1.7 to 1.9 bar, which is past the max efficiency point of the GT30, but achievable.

So I'm perplexed over this as well...............

[GTS-t VSPEC]

Sydneykid, Glad I've got you stumped on this one, I was shocked aswell. I know I only put BP 98 in the tank, mixed in the correct proportions with Octane booster. The injectors have been in there since I bought the car, and the car was 100% stock when I bought it, so I'm confident that there are stock. I would agree that sizing the injetors to meet the application, but seeing as we're not even at 90% duty cycle then the stock injectors are working great.

I'm using the stock fuel pump as a lift to a 3litre surge tank, then a 910 Bosch pump into the Malpassi.

I have the Greddy plenum, 100mm throttle body, custom exhaust manifold, R34GTR intercooler, if that helps with any of your calculations;)