kpr's starlet

[Roman 12,730]

Thats hardly fair though! 

20vs are never good off the line, because the driver cant see the tree through all of the oil smoke 

[kpr 6,116]

I heard muttering in the pits that the resonant frequency of the 20v's effects the timing gear, resulting in inaccurate time slips.     the smoke theory does make more sense

[Roman 12,730]

4 hours ago, Rhyscar said:

Here’s some interesting data about primary tube diameter;

 

This is intereresting to me right now, because it shows how much you can potentially move the powerband around with exhaust side cam timing. 

So assuming you could move the exhaust cam a full 40deg, which mine cant its only about 20 deg, here is the information from this table put in a graph showing how much you could move the powerband peak at a given tuned rpm range: 

(only went to 8000rpm because cbf typing it all out) 



But the trend is that higher the rpm its tuned for the bigger the rpm range is.

So if I had a header designed for say 7500rpm I could only spread the peak by probably 5-600rpm with 20 deg of VVTI.
But then thats not unsubstantial if its a taper away from that peak on either side. I guess you could also move the pulley a tooth on the cambelt.
Will be interesting to see how this relates to some IRL testing in a bit.

Heres the data from the table with a colour scale 



In hindsight stopping my numbers at 8000rpm is dreadful, why even get out of bed for less than that.
But also, CBF doing it again so here we are.
 

[Rhyscar 757]

Love the graph Dave!

In conclusion;

you can spread the peak with vvti by 500rpm

 

stepped headers can spread the peak by 500rpm 

 

Venturi collectors also spread the effective tuning range. 

 

It’s safe to say the higher the rpm the header is tuned for the bigger the returns you’ll get  

 

another interesting point made in the book is that you’ll get maximum gains if you tune the headers for a rpm half way between peak torque and peak hp. 

 

If all the above factors are combined into one header design surely a 1500-2000rpm  ‘powerband’ could easily be achieved. 

 

[Rhyscar 757]

@Roman Dave found this article that claims the effect of variable valve timing when combined with header scavenging waves can be up to 4% 

https://www.mdpi.com/1996-1073/11/6/1545/htm

it discredits the gains as not substantial which I think is incorrect. Another 4% just from correct vvti tuning on 140-150kw is a massive gain! 

Enjoy

[Stu 1,038]

So much 20v love

Good job I have the best 16v there is... stock bluetop awesomeness! 

Remember kids, rev til bust!

[kpr 6,116]

from the cam timing testing ive done (need to revisit on dyno)      can get pretty aggressive   on the overlap,  inlet advance and exhaust retard.   gain a stack of power  everywhere usable  under peak, with minimal if any loss in peak power .   side effect being  power drops fairly fast after peak as can see in my dyno sheets.    going the other way it will try hold onto that peak power for another 500rpm or so.    Inlet had most effect. exhaust done similar but maybe only half or less effect

so yeh pretty much nothing new there ^ .    if you have vvti /vvt  you can have your cake and eat it too.     many years ago i attempted to retrofit a vvt pulley off a 20v onto a 16v,  its possible  but gave up on the idea.

[mjrstar 2,780]

Vct is awesome.

 

Fg falcon will do 60 degree swing on intake and exhaust, there is a silly trend going around that you throw ~30 degrees or more overlap (there is a simple overlap table in the ecu) to make 'ghost cams' at idle.. 

 

I would like vct on my b18c or give it something in the midrange but may settle for some mild cams because stock(ish) ecu life. 

[UTERUS 17,451]

Hell yea. 

 

 

[kpr 6,116]

@Truenotch

Filter vs no filter.   cant remember which one is which, but yeh  zero loss

 

@Roman     red is my normal cam timing.    blue is the inlet cam retarded 8 degrees.     had a play with the exhaust cam. advanced it 5 deg, then another 5deg.  pretty much no change other than a few bumps here and there. maybe slightly better all round with my normal setup, but seems pretty numb to changes.  my normal settings im maxed out on both cams, any further  pistons will eat valves 
i do have a vibration issue with either a wheel or wack axle that screws with the dyno and gives inconsistent  results, right up top at around 180k i need to fix.   / start running it up in a lower gear. 

 

[KP_wag 746]

Daily driving vibratey sparten interior old cars is the way of the future

[kpr 6,116]

The cams make it lovely driving anything under 30kph,  and the gearing makes it a delight to drive over 80kph

[KP_wag 746]

At least you can go faster than 80kmh, DDing the BJ 80kmh is getting up there

[Yowzer 31,950]

Do you have a pre and post intercooler temp sensors to see what difference the intercooler makes?

[kpr 6,116]

wrong thread yo.  but close enough.      only got post iat sensor.  The temps were never really an issue, china intercooler cooled good.   just doesn't flow enough   

[Yowzer 31,950]

Oops haha. Was the first thread I saw.