Max hp´s out of a stock KA head?

[Swedish Mike]

If you use the old x3 rule the KA head should flow 155x3=465bhp when boosting it.(Of course with a solid bottom end and good tuning, we only talk flow now.)How far from the truth is this? Anyone pushed over 400bhp on stock cams and without porting?

155 is a number I had in my head, not sure if it´s correct for the KA24DE?

[KATwo40]

The stock cams start to choke a little when you get into the 430ish whp range. So, that'd be what, about 500bhp?

[C-Kwik]

I'm not sure where this "rule" came from, but when you're boosting, in theory, you should be making nearly as much power over NA as the pressure ratio the turbo is operating at.

Any orafice, such as the head has flow limitations based on mass for a given density. In other words, it will flow a certain volume of air. But if you increase the density of air by increasing the pressure, a higher mass of air will fit in the same volume. If it flows based on volume, there is no theoretical limitation on mass flow as dinsity can be increased as much as everything else can handle.

[eazye2000]

I'm not sure where this "rule" came from, but when you're boosting, in theory, you should be making nearly as much power over NA as the pressure ratio the turbo is operating at.

Any orafice, such as the head has flow limitations based on mass for a given density. In other words, it will flow a certain volume of air. But if you increase the density of air by increasing the pressure, a higher mass of air will fit in the same volume. If it flows based on volume, there is no theoretical limitation on mass flow as dinsity can be increased as much as everything else can handle.

Let me sum this up for C-Kwik. 10lbs of potatoes wont fit in a 5lb sack. Unless you compress them in a trash compactor first.

....don't know if that's what he meant, but it sounded good

[Swedish Mike]

The stock cams start to choke a little when you get into the 430ish whp range. So, that'd be what, about 500bhp?

We measured 15% transmission loss on the S13 with CA and manny transmission, should be the same.

[elpiar]

I'm also curios of this. Cause I'm in the middle of decisions about cams and how much headwork I need to do while aiming up to 400whp.

Inputs?

[klattr1]

The stock cams start to choke a little when you get into the 430ish whp range. So, that'd be what, about 500bhp?

there have been plenty of people to push 500+whp and 600+whp using stock cams (Rick, Duy, Anthony, Barney, PhatKA-T car, Mike Lee, etc)...if someone's KA was "choking" out at 430ish whp, then it was prolly their turbo maxing out or they werent pushing enough boost.

[Swedish Mike]

I'm not sure where this "rule" came from, but when you're boosting, in theory, you should be making nearly as much power over NA as the pressure ratio the turbo is operating at.

Any orafice, such as the head has flow limitations based on mass for a given density. In other words, it will flow a certain volume of air. But if you increase the density of air by increasing the pressure, a higher mass of air will fit in the same volume. If it flows based on volume, there is no theoretical limitation on mass flow as dinsity can be increased as much as everything else can handle.

I know but the "rule" I talked about is just an old (not perfect) way to calculate cam and head flow when you boost N/A engines.No sciense, just a fast guess before you start calculate things.And the stange thing is that it often turns out really well.

And this thread was meant to test this "rule" on the KA, not to win the 2007 science award.

[nissanfanatic]

If you use the old x3 rule the KA head should flow 155x3=465bhp when boosting it.(Of course with a solid bottom end and good tuning, we only talk flow now.)How far from the truth is this? Anyone pushed over 400bhp on stock cams and without porting?

155 is a number I had in my head, not sure if it´s correct for the KA24DE?

I'm doing about 500bhp on stock head/cams right now.

[Swedish Mike]

I'm doing about 500bhp on stock head/cams right now.

That´s just amazing, ported?

[nissanfanatic]

That´s just amazing, ported?

No, stock.

[Swedish Mike]

No, stock.

Good job! The KA is crazy...

[KATwo40]

there have been plenty of people to push 500+whp and 600+whp using stock cams (Rick, Duy, Anthony, Barney, PhatKA-T car, Mike Lee, etc)...if someone's KA was "choking" out at 430ish whp, then it was prolly their turbo maxing out or they werent pushing enough boost.

I stand corrected. Thank you for clearing that up for me. This gives me good vibes about running stock cams w/ mild porting.

[KATwo40]

I'm not sure where this "rule" came from, but when you're boosting, in theory, you should be making nearly as much power over NA as the pressure ratio the turbo is operating at.

Any orafice, such as the head has flow limitations based on mass for a given density. In other words, it will flow a certain volume of air. But if you increase the density of air by increasing the pressure, a higher mass of air will fit in the same volume. If it flows based on volume, there is no theoretical limitation on mass flow as dinsity can be increased as much as everything else can handle.

This isn't always true. For example, the SR head / cams go sonic at around 330whp, regardless of turbo capability. This has been documented many times and there are tons of dyno sheets proving this.

[Swedish Mike]

This isn't always true. For example, the SR head / cams go sonic at around 330whp, regardless of turbo capability. This has been documented many times and there are tons of dyno sheets proving this.

Totally off topic but is it common to use the SR N/A head or cams on the turbo models in USA?According to a buddy (tuned the 915hp one) the N/A head were much better.That was the big difference between the 885hp and the 915hp engines, turbo vs N/A heads.

[nissanfanatic]

Good job! The KA is crazy...

Thanks!

On my next setup, I'm definitely going to at least run 264s... Hopefully I can get some porting done on the exhaust side as well...

[Swedish Mike]

Thanks!

On my next setup, I'm definitely going to at least run 264s... Hopefully I can get some porting done on the exhaust side as well...

I guess you´re on forged internals now, if not, add that to the 264´s.

[KATwo40]

He's on a 100% stock internals engine.

As for the SR heads, NA vs FI, not sure. I don't spend much time on SR's, although I wouldn't mind it.

[nissanfanatic]

Still on stock internals. I'm going for broke on stock internals. Hoping to do 500whp and trap 130mph before they give out. On my next setup, that power should be achieved at or before 20psi.

[C-Kwik]

This isn't always true. For example, the SR head / cams go sonic at around 330whp, regardless of turbo capability. This has been documented many times and there are tons of dyno sheets proving this.

I guess I was thinking about a smaller picture when writing this out so I really only considered flow in terms of volume, but not the changing pressure across an orafice. I'd be curious as to where the SR heads/cams are finding this limitation. Is it the ports themselves or the valve area vs the cam's lift and duration? When air hits supersonic speeds in a head, it's probably going to be in the exhaust side and likely due to a large pressure differential. If larger cams can aleviate the problem, then I'd have to believe that the port is not the problem, but rather the valve opening.

I think we should try to determine where such a limitation would be seen first in a KA. Porting in that of itself would at the very least smooth out flow, but if the valve openings are the first restriction we would run into, then porting would probably not solve the problem. A larger valve and opening up the valve area and/or more agressive cams might.

[GEO]

11hp for ever psi

[crzycav86]

11hp for ever psi

uhh.. nope

[KATwo40]

Ckwik: The SR guys always alleviate the choke with upgraded cams, so I'd venture to say it's duration that's the issue. I suppose stock cams with larger valves could be used, but simply swapping cams is much less involved.

[Swedish Mike]

Ckwik: The SR guys always alleviate the choke with upgraded cams, so I'd venture to say it's duration that's the issue. I suppose stock cams with larger valves could be used, but simply swapping cams is much less involved.

'

Sounds right, turbo cams are usually lame compared to N/A ones.Some engine familys use over 2 mm higher lift in the N/A versions.

[GlacierFreeze]

Ckwik: The SR guys always alleviate the choke with upgraded cams, so I'd venture to say it's duration that's the issue.

Greddy intake manifold works wonders for them too.

[C-Kwik]

Ckwik: The SR guys always alleviate the choke with upgraded cams, so I'd venture to say it's duration that's the issue. I suppose stock cams with larger valves could be used, but simply swapping cams is much less involved.

Then there would probably be little need to port unless the cams get upgraded first and you still run into a flow issue. This could be true for the KA as well.

[Swedish Mike]

Then there would probably be little need to port unless the cams get upgraded first and you still run into a flow issue. This could be true for the KA as well.

That´s often a problem you see on N/A heads, as boosted they can take you to high numbers with everything stock but when you upgrade cams the exhaust ports says no.Often easy to port up and never any intake port problems as the small port turbo heads.

[Edub1]

Anything one does is going to help. The KA heads flow quite well but of course reducing backpressure is going to be of some benefit.

I understand a cam ground for a turbo makes quite a difference, all else equal. As far as bang for the buck that's another issue.

[KATwo40]

Greddy intake manifold works wonders for them too.

It does, but does not overcome the stock cams choking.