264deg Cam on 20V?

[Vezza]

Hi guys,
I've read that the 264deg cam with 9mm lift will work on a BT 20V with stock ecu. However I have a feeling it will require better valve springs and shim under buckets... is this true and how much am I looking to benefit from this, power and torque wise?

[Gunner]

well with such small duration i doubt the shims will be affected, though to run 9mm lift i'd advise better valve springs, and retainers to take the extra strain from the pressure that would be created by heavier springs.

as for the duration ive heard the same thing, that it is safe to use upto the 260-270 degree mark on the inlet side, i have even seen a hks built motor with an adjustable variable inlet pulley. from memory though 260 degree isnt much of an increase over standard.

the specs i heard of, were 26* on the inlet with standard pulley, and 28* with adj cam pulley on exhaust.

dude u wont know what will work till u try it, theres is not enough support for blacktop 20vs in aus, just get a degree wheel and have a play don't have to worry about destroying valves in the process then

[Paw-DK]

WHOA was gonna ask the same question on tech question lol
do you reckon 260 duration cams will make a worth while difference over the standard cams.. power wise

and if 260cams were used with a 8.?? lift way under 9mm will that be able to run on standard ST 20v with a piggyback ecu??
(was planning 288 but don't have money to blow all at once to support and strengthen the engine so using smaller cams for now)

and gunbz-r.. whats a degree wheel? :huh:

[Gunner]

all a degree wheel is, is a wheel with marks of degree on it. u attach it to ur cam pulley, with ameasuring device on the lobe (can't remember exact terminology its a somethin gauge lol), all it does is show u the degree of cam compard to the position of the motor, cams should be set up this way.

ill get all the right terminology and get a bit more detailed later when i have the time tonight

unless someone else knows a better way of explaining it

[Vezza]

<div class='quotetop'>QUOTE (gunbz-r @ Feb 20 2008, 09:25 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=489111)</div>
all a degree wheel is, is a wheel with marks of degree on it. u attach it to ur cam pulley, with ameasuring device on the lobe (can't remember exact terminology its a somethin gauge lol), all it does is show u the degree of cam compard to the position of the motor, cams should be set up this way.

ill get all the right terminology and get a bit more detailed later when i have the time tonight

unless someone else knows a better way of explaining it[/b]

Sweet, thanks dude.
Just for a bit of interesting reading should check out this link, its for the 16v and not all about cams but still a good read none the less...

[rthy]

for the money spent I really can't see this being worth it. For a start both 20V engines come with 250 degree cams and the blacktop has 8.2mm of lift. So it is a pretty small change. I say save up to run an aftermarket ecu.

[Vezza]

<div class='quotetop'>QUOTE (Sam_Q @ Feb 20 2008, 05:05 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=489302)</div>
for the money spent I really can't see this being worth it. For a start both 20V engines come with 250 degree cams and the blacktop has 8.2mm of lift. So it is a pretty small change. I say save up to run an aftermarket ecu.[/b]

Hmmm I wouldve thought it to be the other way round. An aftermarket ecu is expensive, say 600 bux for a 2nd hand microtech, then a decent street tune needs to be done, which will probably cost around 500 bux... and at the end of the day, an aftermarket ecu isn't going to extract much power from a standard 20V unless running larger cams and so on. I don't really see the point in an aftermarket ecu with the 20V's unless your going for something a little more extreme.

[rthy]

on contrary the standard 20V ecu has an overly rich mixture above a certain throttle opening or revs and it also has a very conservate inition map standard. From a highly reliable source (the boss at EFI hardware) the 20V will gain 15% up high and even more in the mid range. Keep in mind that also modifications to the 20v will always be held back by the stock ecu. Yes its expensive but the results are there.

ALso think of the cost of cams:

cams: $400 atleast
new buckets: $25 each? if needed

that might end up at $900 for a very small increase in power

[Delazy]

the tune doesnt just give power increase....but can totally change the way a engine drives....which to some is more important than a wank factor power figure

[Vezza]

Hmm... but it really depends on how far you're going with your engine I guess. It would be a pitty going to an aftermarket ecu and keeping the engine basically stock, which is what I'm really I'm after. Cos anything involving opening up the bottom end is gonna cost some serious cash. The 264deg cams should increase the mid to high range torque and power in a simliar fashion to a tuned aftermarket ecu and at a lower cost. However, is it possible to dial in the cams to their optimum performance without a dyno?

[Gunner]

its very hard to get any sort of full potential with out a dyno, or without a decent data logging comp, as sam said comp first, u need to be able to adjust everything to whatever mod comes next, whats the point in having more aggresive cams if all the timing doesnt suit, and ur running an afr in the 13:1 and some are as low as 12:1 in the power band.

[sotiros86]

<div class='quotetop'>QUOTE (delazy @ Feb 20 2008, 07:59 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=489422)</div>
the tune doesnt just give power increase....but can totally change the way a engine drives....which to some is more important than a wank factor power figure[/b]


oook... by saying that your going against a guy that has tuned countless 4ag engines of various typres.If the tune doesnt affect the power then retard your ignition timing 20 degrees and see how it runs and if it has the same power..

[riojin]

BURN! :owned:

[AmyC]

Stock shims and buckets will be fine. Get some after market springs though as the valves may start to float.

Tune has everything to do with power, Shit tune shit power and a fucked engine in the long run.

[rthy]

you can adjust the exhuast cam angle but chances are it would have a limited effect

[riojin]

i was going to say pretty much exactly what sam said.

stock duration on a 20V is 250 so a 264 will not be very noticable as a power increase. i believe 264 is the maximum streetable but 250 is the optimum.

if you want more power get an afc and a decent tune. youll be able to rev up to 9000 with stock everything and have a NOTICABLE power increase.

if youre going to spend the money on cams you should do things properly. high duration cams (my personal pic for a 20V is 272 intake and 288 exhaust) raise the compression with a thinner TRD metal head gasket, new valves and harder valve springs. all of which you will have to use an afc for.

buy an afc first so whatever mods you buy over time you can tune in. if you can't afford the big bucks for a production afc buy a megasquirt and tune it yourself. its easier than you think.

[rthy]

don't know about the rod bolts holding up at 9000 long term, but 8500 yeah. Otherwise I am tottaly agree with you

[Gunner]

yeah every 9000rpm std 20v i have seen has had stud kits fitted but apart from that, they do quite well from what i've seen, which isnt much but still

nothin wrong with a std bt pullin a healthy 98kw at the treads with very little work done.

[rthy]

stud kits arnt needed, just the rod bolts, luckily the ARP ones are cheap but even better the spool rods are affordable

and yeah your right depending on the dyno 90+ kw atw isnt that hard.

I have a friend with a silvertop that has a good intake, reasable exhuast and an aftermarket tps only ecu and he is pulling soposedly making more power than a 4agze from mid range revs on.

[Vezza]

<div class='quotetop'>QUOTE (Sam_Q @ Feb 20 2008, 11:24 PM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=489587)</div>
stud kits arnt needed, just the rod bolts, luckily the ARP ones are cheap but even better the spool rods are affordable

and yeah your right depending on the dyno 90+ kw atw isnt that hard.

I have a friend with a silvertop that has a good intake, reasable exhuast and an aftermarket tps only ecu and he is pulling soposedly making more power than a 4agze from mid range revs on.[/b]

Hmm... how well does and aftermarket ecu running only off TPS go street wise though, is it a total dog from idle to 3500 rpm?

Could you please find out roughly how much it cost him to tune the ecu as well?
Cheers

[rthy]

from what i have been told the difference in useage and power isnt really there. The reason this is is because of this: the difference in power level between 12.6:1 air/fuel mix and 10:1 isnt that major so they purposefully run a more rich mixture to compensate through parts of the rev range. If done properly a map system is used and after a certain point it switches over to TPS load calculating. For me the reason I am going for an airflow meter is because I still want great fuel economy. You have to keep in mind that the standard 20V map is very crude indeed in the way it dumps the fuel in after a selected throttle opening/rev point.

[Paw-DK]

DAME you guys know knowledge :P

anymore please!

[Vezza]

<div class='quotetop'>QUOTE (Sam_Q @ Feb 22 2008, 10:17 AM) <{POST_SNAPBACK}> (index.php?act=findpost&pid=490444)</div>
from what i have been told the difference in useage and power isnt really there. The reason this is is because of this: the difference in power level between 12.6:1 air/fuel mix and 10:1 isnt that major so they purposefully run a more rich mixture to compensate through parts of the rev range. If done properly a map system is used and after a certain point it switches over to TPS load calculating. For me the reason I am going for an airflow meter is because I still want great fuel economy. You have to keep in mind that the standard 20V map is very crude indeed in the way it dumps the fuel in after a selected throttle opening/rev point.[/b]

Are you sure the standard 20V map is crude?? I thought it was spose to be pretty efficient, maybe slightly conservative, but not crude. I was under the impression that a tuned aftermarket ecu running off TPS was pretty crude, by simply injecting more fuel as the throttle is opened. But apparently this is really the only way to do it when running mega cams. Which is probably good enough if you're not looking at fuel economy or driveabilty, just flat out power.

[Gunner]

not sure on silver top motors, but blacktops are shockin if ur given them a hard time, cruising they're good.

i don't know a shitload about tuning, but to just tune of tps, its pretty dinosaur tech if u get me, from the time ive spent on the dyno trying to get a grasp on tuning, there is alot of power lost through just dumping more fuel in as the tps signal increases. from what i was taught having the ability to set ur own load points thru calculation of afr, tps, map sensor readings, and this is where u get economy aswell as good power and torque curves.

i may not be entirely correct but thats my thoughts on it.

[rthy]

its crude in the fact that it just dumps the fuel in, makes sense though if you think about it. Look at the blacktop motor, it only has a map signal for small throttle openings and then just TPS for the rest just like every other aftermarket tuned system out there so far on a 20V. Either way I hear the standard map on both the silver and black is way too rich, like around 10:1 though a large part of the rev range.

Anyway just a bit of a side note if I hadnt mentioned it but I am still looking to fit an Skyline R31 (RB30 engine) hotwire airflow meter on my big effort 4A hybrid engine I am building with its quad silvertop throttles.