Camshafts Question.

[GTRnewbie]

Hi guys, i own a Skyline R34 GTR V-Spec 2. Modifications include- HKS down pipe, Nismo de-cat exhaust system, Apexi power intake air filters, Mine's ecu, Blitz boost controller. I did a dyno test and the car is 425bhp (engine) and 315bhp (wheels). My target is to get as much as possible with stock intercooler, turbo, injectors and clutch. Hopefully around 450bhp (engine).

Previously i was contemplating whether to change the Mines ecu to a Power FC or a FconV pro. But i think its too costly.

My mechanic advised me to change my camshaft to HKS 264 cams and a fuel regulator (to increase the fuel supply). Maybe a SAFC to fine tune a little. Later perhaps changing my head gasket as well if i have cash to spare. He said this will give me around 450bhp. He said changing the the cams would also give me more torque (is this true?)

Thanks for ure advice.

Edited January 22, 2006 by GTRnewbie

[PurpleR32]

Hi guys, i own a Skyline R34 GTR V-Spec 2. Modifications include- HKS down pipe, Nismo de-cat exhaust system, Apexi power intake air filters, Mine's ecu, Blitz boost controller. I did a dyno test and the car is 425bhp (engine) and 315bhp (wheels). My target is to get as much as possible with stock intercooler, turbo, injectors and clutch. Hopefully around 450bhp (engine).

Previously i was contemplating whether to change the Mines ecu to a Power FC or a FconV pro. But i think its too costly.

My mechanic advised me to change my camshaft to HKS 264 cams and a fuel regulator (to increase the fuel supply). Maybe a SAFC to fine tune a little. Later perhaps changing my head gasket as well if i have cash to spare. He said this will give me around 450bhp. He said changing the the cams would also give me more torque (is this true?)

Thanks for ure advice.

<{POST_SNAPBACK}>

Your statement is a little confusing. You can afford a 34 V-spec 2, but a power FC and tune is too costly? You want to keep stock injectors, but have cams and change head gasket?

You didnt mention where you are from, so i will assume Australia. Ditch the Mines ECU, forget SAFC, Go the Power FC and re-tune. I doubt the stock injectors will make the desired power (and definetly DO NOT get a fuel pressure reg to bump up the pressure. If the injectors are maxed there maxed)

If you want this power

*Change Injectors 550 - 700's (700 will save you doing them again if you want more power later)

*Get a Power FC and get a reputable tuner

*Stock Intercooler is fine

*Cam Gears

*If they are steel wheel turbs (which i believe the Vspec 2 came out with) they can handle 1 - 1.2 bar boost

see how you go with that combo.

[pnblight]

the turbos, injectors and afms will be your limiting factors at round 400rwhp(480bhp)

order of best buys for returns in hp

1.APEXI pfc ($1000) with hand controller A MUST!!!!!

2.SARD 700cc injectors($700) i would replace afms at same time a set of rb20/25afms ($300 sec hand)

3. TOMEI poncams 260deg 9.15mm lift with adjustable wheels (~$1300)

*forget about head gasket unless you blow one as it is a hugh costly job and will give you next to nothing at this level of mod.

*do the cams last as if you dont upgrade the injectors and afms first you will not be able use them to there fullest and there for waste time and money tuning.

*the r34 turbos are ceramic and i would not run them above 1.1bar at the very most unless you want to rebuild the motor like the r34 i just finished rebuild due to a blow r34 ball bearing turbo.

*if you get serious about a bit hp upgrade your turbos to something like gt2560r 707160-5 or the 2530 HKS as they are bolts and give the best around package power and responce

pete

[Turbo_fb]

Is there any big gain by changing to adjustable cam wheels and keeping the oem cams?

[Sydneykid]

Is there any big gain by changing to adjustable cam wheels and keeping the oem cams?

<{POST_SNAPBACK}>

Yes

cheers

[Abo Bob]

Ding ding ding ding ding ding ding ding ding ding ding.

[blind_elk]

Ding ding ding ding ding ding ding ding ding ding ding.

<{POST_SNAPBACK}>

I thought it went:

ka-ching, ka-ching, ka-ching...

PurpleR32, I believe your comment about the FPR and maxed out injectors is incorrect (and it's "they're maxed out"). If you increase the pressure behind the injector, then more fuel will be released when the injector opens. Therefore, you can reduce the duty cycle of the injector at higher fuel pressures. I have read somewhere that this is a far more efficient means of extending the power than by increasing the flow of the injectors; when delivering the same volume of fuel, the spray pattern of a standard injector at the higher pressure is superior to a large injector at lower pressure, so the ability of the engine to combust the A/F mixture is enhanced.

[PurpleR32]

I thought it went:

ka-ching, ka-ching, ka-ching...

PurpleR32, I believe your comment about the FPR and maxed out injectors is incorrect (and it's "they're maxed out"). If you increase the pressure behind the injector, then more fuel will be released when the injector opens. Therefore, you can reduce the duty cycle of the injector at higher fuel pressures. I have read somewhere that this is a far more efficient means of extending the power than by increasing the flow of the injectors; when delivering the same volume of fuel, the spray pattern of a standard injector at the higher pressure is superior to a large injector at lower pressure, so the ability of the engine to combust the A/F mixture is enhanced.

<{POST_SNAPBACK}>

Well im glad you read that you can do that and didnt actually do it. Becasue if you were aiming for that sort of power on stock injectors, your engine would be running so lean its not funny, or the injector would have failed due to stress on the component (stayed open continually injecting fuel) causing it to bend a rod.

The trouble with what is written above is that your dont want to deliver the same volume of fuel. It is correct in saying the the spray pattern of a standard injector at the higher pressure is superior to a large injector at lower pressure, but that assumes it is within the capabilities of that smaller injector. In this case it is not within the capabilities of that injector. You want to deliver more fuel than standard (or what is currently being delivered) to safely attain the desired power and A/F Ratio.

[Sydneykid]

You have to be very carefull with increasing fuel pressure to achieve an increae in flow. My fluid dynamics is a bit rusty, but what I do remember is that the flow increase is way less than the pressure increase.

For example, I have increased the fuel pressure from 36-38 psi (standard Skyline fuel pressure) to 50 psi, that's a 35% increase in pressure. But the flow only increased by around 10%. I had to stop at 50 psi because the fuel pump (Bosch) was only rated for flow at 73.5 psi. That left 73.5 - 50 = 23.5 psi for boost.

In addition to the adjustable fuel pressure regulator, I had to replace all of the fuel lines (from the tank to the engine) with braided lines and screw fittings, as the standard clamp on hoses were unable to handle the extra pressure. All up (including labour) it would have been almost cheaper to buy bigger injectors and then sell the GTR ones.

cheers

[pnblight]

SK spot on as usual

but i will add that as you up the pressure on the pump its flow rate goes south down time, like a direction reverse of the flow/pressure relationship of the injector. If you increase the pressure the pump has to supply by 10% you will lose alot more than 10% total flow from the pump.

pete

ps my R33 gtr runing std fuel pump and std pressure on to 700cc injectors has made 530rwhp with duty cycle to spare on injectors.