rb25det forged question

[r34killa]

I had purchased (for a good price) a 25det neo engine forged from a family member of a friend who sadly passed away. 

CP o/s Pistons, eagle rods, arp everything, kelford cams, springs and gears, polished inlet and outlet ports, nitto head drain,  N1 oil pump with billet gears, crank collar, gates racing belt, NZ wiring trigger kit, sinco manifold, PSR 5855 dual ball bearing turbo, front facing plenum and rail, 90mm throttle body, turbo smart wastegate 50mm, r35 coil conversion, 535lph fuel pump, 100mm intercooler, haltech 2500 elite (and more that I would need to check up on but you get the idea) 

The engine forge itself was not done by me, however, all the other parts (wastegate, coils turbo, etc) are parts I've purchased. The issue I have is that the VCT has been removed by the looks to run bigger cams? I haven't seen this done before and struggling to find online why he would have done this... If anyone has more knowledge on why this would be done and how it affects the overall build that would be great. I'm hoping for 450kw what do you guys think about the parts I've chosen to achieve this?   

[GTSBoy]

16 minutes ago, r34killa said:

The issue I have is that the VCT has been removed by the looks to run bigger cams? I haven't seen this done before and struggling to find online why he would have done this...

Could be. Specs on the cams? If they're too big for VCT, they're too big for VCT. Otherwise, the actuator could have been stuffed and he sidestepped the problem.

450kW measured how and where?

[r34killa]

aiming for 450kw to the rear wheels.. and that's the issue the cams don't have the engraving on them but they look big.

what do you think the effect of having no VCT and going bigger cams will have? VCT is normally something you would not want to remove

[bcozican]

I had vct removed with big cams on my previous track rb25 build as tuner didnt like it and said it was running in higher rpm so didnt need

If running it on track hard at higher rpm mostly avg joe like me prob wont know / feel much diff unless on really tight track and then you just go down a gear but I had sequential 

But if still manual and not track vct extremely still beneficial 

 

Rb26s dont have vct and seem to still go good

 

Rather have it than not though but not a complete deal breaker depending

[Dose Pipe Sutututu]

34 minutes ago, r34killa said:

what do you think the effect of having no VCT and going bigger cams will have?

Reduced low down torque, so your turbo will come on later.

And if it's a single scroll setup, expect a later rpm for your turbo to come on song.

Removing VCT is silly on a mild car, especially if predominantly for street use.

[r34killa]

Read my reply below.

Edited May 31, 2023 by r34killa

[r34killa]

11 hours ago, bcozican said:

I had vct removed with big cams on my previous track rb25 build as tuner didnt like it and said it was running in higher rpm so didnt need

If running it on track hard at higher rpm mostly avg joe like me prob wont know / feel much diff unless on really tight track and then you just go down a gear but I had sequential 

But if still manual and not track vct extremely still beneficial 

 

Rb26s dont have vct and seem to still go good

 

Rather have it than not though but not a complete deal breaker depending

 

11 hours ago, Dose Pipe Sutututu said:

Reduced low down torque, so your turbo will come on later.

And if it's a single scroll setup, expect a later rpm for your turbo to come on song.

Removing VCT is silly on a mild car, especially if predominantly for street use.

It's a street car, manual. Won't be driven on the track much (if at all). I agree that removing VCT isn't ideal but this was done by the previous owner. What would the other option be? Do you think it would be better to get different cams and reinstall VCT? 

Other than turbo coming on later and lower torque will the overall power of the build be affected much? and are these going to be noticeable later turbo etc? 

Edited May 31, 2023 by r34killa

[Kinkstaah]

Yes, but 450kw at the wheels and street only car is also... pretty shit. 

VCT gives you two cam profiles. One aimed at low down power, and a switchover for high RPM power. You literally get the best of both worlds.

Removing VCT and choosing a bigger cam is really just doubling down on High RPM Power.

If you drive the car at 5000-8000rpm all the time, No VCT and bigger cams make sense. But 100% of engine running and 5000-8000rpm is obviously at a track.

AVERAGE power is better than peak power.

Really, you want power where your RPM needle is at the majority of the time for a fast car, a G30-770 will be a pretty good turbo with modern tech - you're going to like it either way, but I think the 'better overall car' is with VCT and stock cams (maybe poncams). Is it worth the money? For what you want the car for? Eh probably not. There's value in just not worrying about it and driving the car for what it is.

But I'll say it again, a car that makes 435kw and comes on 1000+rpm earlier and has a much fatter midrange is much better than a car that makes 450kw where that 15kw advantage only exists at 7001+ RPM.

[GTSBoy]

That turbo is also not likely to make 450rwkW. 400 maybe. 430 or so if the planets align.

Regardless 450rwkW is not a street setup. It will be no fun to drive on the street.

[Kinkstaah]

I'd argue its possible. People have made 450KW on a GTX3076, and a G25-660. G30-770 could get there. Especially if you do things like delete VCT for big cams to keep boost up at 8000rpm....

But max effort there reduces overall goodness at least in my opinion.
 

[Dose Pipe Sutututu]

2 hours ago, GTSBoy said:

Regardless 450rwkW is not a street setup. It will be no fun to drive on the street.

When you're in Sydney next, come drive my shit box. It's not 450kW, but it's 437kW, we can make it 450kW if we drop the cat, and drop the plumb back lol...

Has VCT, has 8600rpm limiter, has twin scroll.

[GTSBoy]

1 minute ago, Dose Pipe Sutututu said:

When you're in Sydney next, come drive my shit box. It's not 450kW, but it's 437kW, we can make it 450kW if we drop the cat, and drop the plumb back lol...

Has VCT, has 8600rpm limiter, has twin scroll.

Are you suggesting that you can use the 450+rwkW on the street? Or are you suggesting that it comes on boost early enough and gently enough that you can have fun long before it gets to 450+? Or are suggesting that we just pretend there are no laws, no cops and no other road users and just use the 450+?

[Dose Pipe Sutututu]

1 minute ago, GTSBoy said:

Or are you suggesting that it comes on boost early enough and gently enough that you can have fun long before it gets to 450+?

This

 

1 minute ago, GTSBoy said:

Or are suggesting that we just pretend there are no laws, no cops and no other road users and just use the 450+?

If you're keen, you can do it on your own, I'll stand outside and watch.

 

 

[GTSBoy]

17 minutes ago, Dose Pipe Sutututu said:

This

17 minutes ago, Dose Pipe Sutututu said:

If you're keen, you can do it on your own, I'll stand outside and watch.

 

[Dose Pipe Sutututu]

27 minutes ago, GTSBoy said:

 

But aren't we in Mexico? LOL...

 

Also you've probably worked out I'm not precious with the car, all my mates drive it on the track.

[r34killa]

4 hours ago, GTSBoy said:

That turbo is also not likely to make 450rwkW. 400 maybe. 430 or so if the planets align.

Regardless 450rwkW is not a street setup. It will be no fun to drive on the street.

why wouldn't it be fun to drive? This same car used to make 300kw and I was looking for an upgrade. I will be running it on low boost most of the time anyways thinking somewhere like 350kw.

Out of curiosity what other upgrades would you recommend doing/getting for reliability and power? what is restricting the build at the moment the turbo? 

Edited May 31, 2023 by r34killa

[Murray_Calavera]

7 minutes ago, r34killa said:

why wouldn't it be fun to drive?

Everyone has their own definition of what is fun and what isn't. 

As a guess, people saying big power builds aren't fun on the street is because when driven around obeying the road rules, the big power car is slow as hell. Then when you want to use the 450kw, you can't put the power down. Finally when you do manage to put all 450kw down, it turns out your doing 150kph+ on the motorway...

[admS15]

On 31/05/2023 at 3:00 PM, Dose Pipe Sutututu said:

This

 

If you're keen, you can do it on your own, I'll stand outside and watch.

 

 

Address please, I'll be on the next flight in😉

[admS15]

On 31/05/2023 at 5:23 PM, Murray_Calavera said:

Finally when you do manage to put all 450kw down, it turns out your doing 150kph+ on the motorway...

And you have a broken gearbox.

[Dose Pipe Sutututu]

1 hour ago, admS15 said:

Address please, I'll be on the next flight in😉

You already have my address, when I sent you car parts lol