Jump to content
SAU Community

Recommended Posts

I still cant understand how some of the "stock" r33s etc get into the 13s down south!

None up here can do that, and my r34 with a cat back was only running 94mph. Which would need a crazy launch to even get close to a 13.

I dunno how you guys do it :)

  • Replies 142
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

Hey guys, i scanned the dyno readouts so you could see how it makes power. The 260kw run was done on a 38 - 40 degree day, i think thats why its a little lower.

I really want to find out why my mph is so low. I was going to put some cams in but maybe i have some sort of other problem which i should fix first.

Any help would be appreciated.

Mike.

post-10526-1202365108_thumb.jpg

post-10526-1202365128_thumb.jpg

Dyno sheet doesnt mean anything dude, because we've told ya it wrong based on the very low MPH/ET you have for that power/setup

I know what your saying but the car feels very fast to drive. Alot faster than 220kw worth. I posted the dyno sheet to show the power curve.

The car would have to have major issues if its running a 35r with 18psi and only putting out 220atw.

Could it be cause the car maybe drops of boost through gears?

Mike

I know what your saying but the car feels very fast to drive. Alot faster than 220kw worth. I posted the dyno sheet to show the power curve.

The car would have to have major issues if its running a 35r with 18psi and only putting out 220atw.

Could it be cause the car maybe drops of boost through gears?

Mike

If it drops off very badly then could explain some/most of the lack of mph. Give it a rev, son!

For what its worth my car traps at ~112mph on street tires on ~14-15psi with a GT30R making 270rwkw on a hub dyno, BUT its not running a very nice power curve - internal wastegate slows the spool from 11psi to 14psi quite bad so reaches 11psi by 3400rpm, but then only 14psi by 6000rpm. Have an AVCR to go in, so will have to try again with same peak boost/power but fuller boost/power curve.

Edited by Lithium
For what its worth my car traps at ~112mph on street tires on ~14-15psi with a GT30R making 270rwkw on a hub dyno, BUT its not running a very nice power curve - wastegate slows the spool from 11psi to 14psi quite bad so reaches 11psi by 3400rpm, but then only 14psi by 6000rpm. Have an AVCR to go in, so will have to try again with same peak boost/power but fuller boost/power curve.

Great example. Could also be a reason.

The car doesn't feel like it drops off boost between changes, but when i had a screamer pipe on it, i could hear that the gate would be closed for the first instant of 3rd gear.

BTW, thanks for the help

Mike.

i doubt it. i should be able to realise if its slipping. it puts the power down in every gear. im thinking its got more to do with it dropping a bit of boost going into 3rd gear.

I actually brought the clutch off andrew and he told me it would be fine for 270rwkw.

Will probably change cams and get a boost controller for it to see if i can bring the boost on a little earlier.

Mike.

Check out the following expertly produced dyno graph showing two cars each making 270kW.

Which car is quicker over the quarter mile?

p.s. fear my mspaint skills

it has to be car b! caus everyone knows a fast car is one with the greater area above the curve :sorcerer:

The car doesn't feel like it drops off boost between changes, but when i had a screamer pipe on it, i could hear that the gate would be closed for the first instant of 3rd gear.

Not sure if you are referring to my example or not - but what I meant by mine is that the wastegate actually cracks open before I reach 1bar. It doesn't fully open, but opens enough to greatly reduce the rate that it builds the last 3 psi or so and makes 4000-6000rpm feel quite hollow after you have felt how the car goes from 6000-7000rpm. I have an internal wastegate however.

See boost curve (and this is done on the dyno in 4th gear, where it will build much more optimally than on the strip):

Boost280kw.png

I'd love to know, if its not too much of a hijack - if the experienced racers here think I could gain a bit on the strip when I have the AVC-R in there and set up to hold ~1bar flat?

Edited by Lithium

What boost controller are you using on that? Something like a Turbosmart eBoost2 will allow you to set a "gate pressure" which will stop the gate from creeping open before a specific manifold pressure. You can use this feature to bring boost on much earlier in the rev range and use play with this function and the sensitivity of the unit to control spiking caused by the less gradual rise in boost.

What boost controller would be best for an external gate? Im looking at the eboost 2, hks evc V and the blitz sbc spec R.

Mike.

What boost controller are you using on that? Something like a Turbosmart eBoost2 will allow you to set a "gate pressure" which will stop the gate from creeping open before a specific manifold pressure. You can use this feature to bring boost on much earlier in the rev range and use play with this function and the sensitivity of the unit to control spiking caused by the less gradual rise in boost.
What boost controller are you using on that? Something like a Turbosmart eBoost2 will allow you to set a "gate pressure" which will stop the gate from creeping open before a specific manifold pressure. You can use this feature to bring boost on much earlier in the rev range and use play with this function and the sensitivity of the unit to control spiking caused by the less gradual rise in boost.

I had a Turbosmart bleed valve in there for that run and for my 13.3 @ 112, but am installing an Apexi AVC-R soon. I can set the target manifold pressure for several different RPM zones as well as the "gain". Also can configure adjustment for dealing with spiking or boost dropping, and have gear specific adjustments to "gain" etc to have different effects or correction in different gears.

Powerful wee unit, if you are inclined to learn how to use it properly - unlike the majority who just set a target boost level and hope it works it out.

I just ran a bleed valve with my gate.

Ideally your gate spring should be as close to the boost you want, and then you dont need a EBC at all as the wastegate is doing it job correctly by regulating the boost off the spring.

If you have a 10psi spring, and run 20psi boost, your going to have it gate creeping in almost every gear

I just ran a bleed valve with my gate.

Ideally your gate spring should be as close to the boost you want, and then you dont need a EBC at all as the wastegate is doing it job correctly by regulating the boost off the spring.

If you have a 10psi spring, and run 20psi boost, your going to have it gate creeping in almost every gear

However as mentioned earlier, I personally have an internal wastegate - the reason I had not bothered with any other kind of boost control is that I thought the gate should close enough to do its job. Apparently I was well wrong, Cubes runs a similar internal gate setup and gets similar - before it reaches its sprung pressure it creeps open and slows the rate it builds the last few psi quite severly.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...