Some good results from retarding exhaust cam

[steel_3d]

Do you guys know what cam timing changes would help emissions with HKS 272/272's? Sorry if this would be considered a hijack.

 

[dsm-onster]

Do you guys know what cam timing changes would help emissions with HKS 272/272's? Sorry if this would be considered a hijack.

Overlap can increase negative emissions. That's all I know. Perhaps, advance the exhaust and/or retard the intake cam? I don't know. I've seen 272s pass emmisions here in Northern VA where the 264s fail .

 

[mirkoelek]

i dont care about mission test and rough idle or ... i just care about more power and i dont quite understand what are you guys doing with your cams.... i do have dsmlink and i can change timing on it...is there still something i can do with mine camgears. When i was replacing mine t-belt those two midlle holes on camgears wouldnt match and be in the line with two outside holes...is this normal

 

[ECLIPSEESPILCE]

Valve timing and ignition timing are two different things.

 

[mirkoelek]

Valve timing and ignition timing are two different things.

i kinda was thinking about it, but still is not clear to me

 

[ECLIPSEESPILCE]

Ignition timing is when the spark is fired relating to the crankshaft top dead center. Valve timing is when the valves are opening letting intake air in and exhaust out. I hope this helps as i am bad at putting my thought into words.

 

[ECLIPSEESPILCE]

Igntion timing is when the spark is fired in relation to the piston top dead center. Valve timing is when the valves are opened to allow intake air in and exhaust gasses out.

 

[ECLIPSEESPILCE]

oops i did not see it went to a new page so i reposted. sorry!

 

[mirkoelek]

oops i did not see it went to a new page so i reposted. sorry!

its all right, i appriciate... So is there something that i could do to make more power by adjusting my camgears and that is not complicate to do....

 

[mirkoelek]

ive heard that you could damage your engine if your timing marks are not on its place

 

[ECLIPSEESPILCE]

Engine damage can occur if your gears are off but i am not sure by how far. If your belt breaks the pistons will interfere with the valves. I have installed my timing belt off one tooth and no damage occurred just poor running. I then installed it correctly and all was good. I have no experience with cam gear adjustment for more power. Sorry

 

[mirkoelek]

Engine damage can occur if your gears are off but i am not sure by how far. If your belt breaks the pistons will interfere with the valves. I have installed my timing belt off one tooth and no damage occurred just poor running. I then installed it correctly and all was good. I have no experience with cam gear adjustment for more power. Sorry

That is ok, i bought my car with the web cams in it. When i tryed to replace timig belt, camgears marks were not inline. Two middle ones were 5mm uder the line of the side marks.

 

[allgripnoslip]

Ive witnessed a dyno session at SBR where a 2g sporting an adjustable cam gear on the exhaust netted 15 whp from retarding the cam 5-7* I'm pretty sure it was 7*... It idled fine, but it also had some tuning equipment.

 

[dsm-onster]

Ive witnessed a dyno session at SBR where a 2g sporting an adjustable cam gear on the exhaust netted 15 whp from retarding the cam 5-7* I'm pretty sure it was 7*... It idled fine, but it also had some tuning equipment.

Was this with stock cams or upgrades?

 

[talonkev]

Im really interested in this. I have stock cams in my car now, and I have an old set of cam gears, so i was thinking of doing what dsm-onster did. I was planning on machining a new hole in the gear to give me around a 3.5 degree retard. From what I have read on the forums, and have been told, 7 degrees is a bit extreme, especially for stock cams. Can you give us more info on the setup this car had?

 

[dsm-onster]

Small 16g, stock fuel, Stock 1G maf.

I upgraded to 650s and MAFt (blow thru). All my knock went away and I ran it like this until my 18G. i found that I was in fact losing a little more up top w/ the 18G than I liked. That wasn't a big deal w/ the Small 16G. The loss up top would me more significant w/ a stock 2g intace mani and head probably. However, I like having slightly peaky engine. Many would prefer the quick spool. She will lope a bit set like this. But, I think it's worth it, if quick spool and torque is your fancy.

 

[allgripnoslip]

Was this with stock cams or upgrades?

Stock engine except for the cam gear. SBR 20g, fmic and afc. Nate dawg was doing the tuning and noticed the cam gear and adjusted it and they did another run and picked up 15whp. it was like 315 awhp then it hit 330 awhp. I think the injetors were 6XXcc

Hell Ill do this little mod when I change my timing belt this summer. 3.5* sounds good for me.

 

[cfisher]

Might be off topic but I just checked my ignition timing on my logger and it states 10" at idle. I thought it was supposed to be closer to 5".WTF

 

[pneumo]

Might be off topic but I just checked my ignition timing on my logger and it states 10" at idle. I thought it was supposed to be closer to 5".WTF

Yes it is off topic, and the timing you see on the logger is not the same as your base timing. 10 degrees at idle on the logger is normal.

 

[Bohrn]

props man!! thats some clear thinking followed up by some follow thru. Nice job. I might actually put my Fidanza cam gear in and, to honour you, give my exhaust cam 3.7 deg of retard.

 

[talonkev]

My water pump gasket started leaking on me so I decided it was time to try retarding the exhaust cam. I retarded it exactly 3.5 degress. The engine idles normal and doesn't sound any different than it used to, but it does feel as though it pulls harder up top where the stock cams and 16g used to fall off, it might spool faster, but i havn't really noticed it. This is on 24 psi.

 

[Bohrn]

you know, its kinda funny. I put an adjstable cam gear onto my exhaust cam as well lately. I tried retarding it 4 deg. My car and I didn't really like it. Thing idled lower, and not nearly as nicely. It spooled faster, but it died off sooner too, loss of power up top. As well, it did not hold boost much past 5500. At 7000rpm, it only had about 17psi, whereas before I could hold 22psi up till about 6200 and then it would fall off to about 20.

So, the next day I dialed in 4deg of advance. Now the car idles better than stock, had EXCELLENT emissions test results, still has good throttle response and things like that. But the big thing is it pulls harder for longer up top, and holds the full 22 psi of boost!!

I went from a best mph of 105.25 for the stock setup to 107.66 with it like this. I also ran 2 12.9 second passes (12.90 and 12.91)

So at least on my car, it seems that advancing the exhaust cam is the way to go. I haven't tried more than 4deg, but it seems quite nice like this.

 

[WatchItExplode]

Stock engine except for the cam gear. SBR 20g, fmic and afc. Nate dawg was doing the tuning and noticed the cam gear and adjusted it and they did another run and picked up 15whp. it was like 315 awhp then it hit 330 awhp. I think the injetors were 6XXcc

Hell Ill do this little mod when I change my timing belt this summer. 3.5* sounds good for me.

I'll take your word for it that it picked up 15 whp, but is that 15 peak whp? Do you remember what RPM it was? Was there any loss in power after retarding the cam, or was there at least some gain all the way across the board?

 

[allgripnoslip]

I didnt notice, I just saw that peak power increased 15 whp. Nate was tuning it for peak power.

 

[TargeT]

Just FYI,

There's no universal cam adjustment that will net you any certain HP number. its very engine / sept up spesific and definatly not limited to just adjusting the exhaust cam

you'll get the best results from adjusting both intake and exhaust cams, if you go over 15* or so your going to tap valves (maybe its a higher *, don't remeber off hand) so be careful


to do this right, get adjustable cam gears, a logger & make small adjustments till you find the sweet spot. on stock cams you won't gain too much, with aftermarket cams the gainswill be considerable.


another note. if you change your timing belt and the marks on your cams don't line up, you changed your timing belt wrong, you have to take the slack OUT of the timing belt between the cam gears, this means you'll have tension up there & have to keep the belt wraped on the cam gears to hold it in place

Hope that helps out