Cam Choice For 500Kw Rb26

[wolverine]

The cylinder pressure spike would be (if it is a good simulation) detonation - that'd be due to being octane limited. Cylinder pressure would go up exponentially if you went driving past the point of being knock limited on the mission for more power, but gaining power using controlled combustion should not be anywhere near exponential.

This is my understanding.

The guys at Unigroup have logged in cylinder pressures on some bigger budget builds including Nitro Harleys. Yavuz was more than happy to take some of us 'tragics' through some of the data after one of his tuning workshops had concluded. Nitro in cylinder pressures are a frightening thing when you think about having a piston pointing at your nuts.

If you have a reasonably knock resistant fuel I can't understand why you would decompress and engine and then go and re-compress it with air from a turbocharger.

(keyboard warrior only here and I bet with big power builds that knock sensitivity, as static compression goes up, needs to be considered particularly as a large framed turbo starts pushing serious air).

[scotty nm35]

How many of those Nitro bikes have high static compression though?

I have still yet to see a high comp (11-12:1+) engine putting out big numbers on e85. Does anyone have some results to share? I can only go by what my tuner believes, which is I will hit issues over 600hp with excessively high cylinder pressures. I need an engine that will remain reliable with continuous track use, not a one run wonder then pull it down to replace the rods, bolts and inspect pistons (like a nitro drag bike.)

[HYPED6]

Hmm, quick question.

What if the target power was 700rwkw? Does this change anything?

[HYPED6]

And the fuel was say 109, or C16 or methanol?

[Ryan1200]

How many of those Nitro bikes have high static compression though? I have still yet to see a high comp (11-12:1+) engine putting out big numbers on e85. Does anyone have some results to share? I can only go by what my tuner believes, which is I will hit issues over 600hp with excessively high cylinder pressures. I need an engine that will remain reliable with continuous track use, not a one run wonder then pull it down to replace the rods, bolts and inspect pistons (like a nitro drag bike.)

Not all that popular in OZ the s2000 F20C runs 11:1 (USDM) 11.7:1 (JDM) and is frequently boosted hard.

Check this out for a stock motor with valve springs and cams

Edited October 11, 2012 by Ryan1200

[wolverine]

How many of those Nitro bikes have high static compression though?

I have still yet to see a high comp (11-12:1+) engine putting out big numbers on e85. Does anyone have some results to share? I can only go by what my tuner believes, which is I will hit issues over 600hp with excessively high cylinder pressures. I need an engine that will remain reliable with continuous track use, not a one run wonder then pull it down to replace the rods, bolts and inspect pistons (like a nitro drag bike.)

Sorry, I got slightly off topic Scotty. I wasn't trying to directly compare nitro powered cars just talking about the in-cylinder pressure measurements I saw.

[wolverine]

Hmm, quick question.

What if the target power was 700rwkw? Does this change anything?

Love a long answer if you are kind enough to share your knowledge in this area.

[R31Nismoid]

Hmm, quick question.

What if the target power was 700rwkw? Does this change anything?

Stop asking loaded questions Sean and just launch into it already

[Sub Boy32]

Just because it seems it can be months between Sub Boy's posts (sorry Chris if you pop back in soon) his car is on 98, and 20psi was a limit they hit with the internal wastegate setup.

Cheers Lith, Yeah I don't come on here often enough haha!

The cams were set up more for response when it became obvious we couldn't get any more boost through the IWG. With the way my turbo makes it's power, and it's limited hotside size (Yet to be proven is the problem) I think I could have got away with a set of 270deg cams and probably made better response again, But I think later down the track I will end up going with the twin EWG 1.05a/r hotside on the EFR, so they will be better suited for that I think.

.....But for now I just want to get it on the road!

[BMYHOE]

Hmm, quick question.

What if the target power was 700rwkw? Does this change anything?

I would run lower CR with that power.

sounds like GT4* territory and 30+ PSI

[Lithium]

700wkw on what fuel and for what use?

[BMYHOE]

Not all that popular in OZ the s2000 F20C runs 11:1 (USDM) 11.7:1 (JDM) and is frequently boosted hard.

Check this out for a stock motor with valve springs and cams

Haha i love the end part

[Lithium]

From the Supra world: http://www.supraforums.com/forum/showthread.php?680955-10.5-1-CR-numbers

[HYPED6]

Im not being silly. Maybe my horsepower is different to every

Stop asking loaded questions Sean and just launch into it already

Nothing loaded here Nismoid, Just wondering if any one would divulge there secrets when the anti is upped slightly.

Maybe I am getting old, and remember getting Smash Hits 88 on record for christmas as a kid..... But 500rwkw is a shit load of power. And people are making it on 35x's? I must be doing something wrong.

[HYPED6]

700wkw on what fuel and for what use?

Drag, or track, or ski boat. Either way I don't think it would matter.

You can choose the fuel. If the correct fuel for the application is used then it shouldn't matter what it is.

[R31Nismoid]

Im not being silly. Maybe my horsepower is different to every

Nothing loaded here Nismoid, Just wondering if any one would divulge there secrets when the anti is upped slightly.

Maybe I am getting old, and remember getting Smash Hits 88 on record for christmas as a kid..... But 500rwkw is a shit load of power. And people are making it on 35x's? I must be doing something wrong.

hehe you do it a lot, its good to read your posts

Ye the 500rwkw was achieved with the old IT sensor trick, the MPH told the story on that one (it was way down).

[NXTIME]

Exactly.

Like the old saying goes..."When the flag drops, the bullshit stops"

Blacktop dyno is never wrong

Maybe it's time for a "500(rw)kw thread"

[mico]

4 sure but who is in it ?

[Tyranus]

Maybe it's time for a "500(rw)kw thread"

Definitely is!

4 sure but who is in it ?

Me, soon enough

[HYPED6]

well.... Im no expert but how about a 130 mph thread

Any skyline with 400rwkw should do 130mph. Im sure this would be way more interesting than a 500 kw thread.

And back on topic.

All this rubbish about compression ratio and boost I have only found interesting when I found a gudgeon pin on my dyno floor after a power run.

And this was a built engine making way less power than a stocker. Then and only then I gave a shlt about compression ratio.

But tuning engines at the track, when the pressure is on and everyone wants to go fast I go against what everyone "says".

I run cylinders too hot, run way too much boost and way wrong mixtures on cast pistons and the things are flying! On heaps of compression and heaps of boost. But I am a hawk on the engines and monitor everything.

And I guess what. If they are laggy...... we don't change compression.... we change the engine. Adjust cam timing, inlet manifold.... add vct.... what ever it takes to make the engines more efficient at lower engine speeds without sacrificing top end. And if it does sacrifice top end, we move rev limiters and diff gears.

yes you can run 9:1 and 50 psi and 175 shot of gas. I can even show you the pistons (stock cast) But without the perfect engine combination your will make 464rwkw and get to 7254rpm at 36psi and literally push the engine through your sump on to the dyno floor.

I can also show you this lol

Work out exactly what you want out of your engine. If you want horsepower, go to a happy dyno save heaps of money and leave the track for everyone else

Edited October 13, 2012 by HYPED6