n/a cams working against turbo setup???
he my tuner said my n/a toda cams are causing my mega flat spot in the mid range. this in on a b16 , he said n/a cams have high lift and long duration n o a boosted set up you want high lift but a short durtation
so was looking a doing the head completely wot you thinks of this - skunk2 turbo cams stage 2 skunk2 pro series intake skunk2 70mm T/B skunk2 valvesprings skunk2 retainers anyone used the turbo cams from skunk2? stage 1 or 2? any other reccomendations ? aint got a scanner here the now but the graph kinda goes like this 3k -105lbs 3.5k -112lbs 4k -128lbs 4.5k -130lbs 5k -139lbs 5.5k -137lbs 6k -126lbs 6.5k -129lbs 7k -141lbs 7.5k -152lbs 8k -155lbs 8.5k -162lbs all the torque fig thru rev range its b16 stock internals ,drag gen 3 kit @7psi with toda cams thanks for any help you guys give |
Re: n/a cams working against turbo setup???
i will be running the NA stage 2s
play with the gears and timing and you should see gains |
Re: n/a cams working against turbo setup???
i think your tuner was LAZY. n/a cams are fine on a boosted motor. find something that favors the exhaust (sohc guy so i dont know dohc specs) and you will be better off as well. i bet he could have added a little more timing to the midrange to get rid of that dip anyways. whats the HP look like???
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Re: n/a cams working against turbo setup???
240hp @ 7psi
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Re: n/a cams working against turbo setup???
You want ITR/CTR or GSR cams. These threads have some good info.
http://forums.evans-tuning.com/viewtopic.php?t=1623 http://forums.evans-tuning.com/viewtopic.php?t=2341 http://forums.evans-tuning.com/viewtopic.php?t=1744 |
Re: n/a cams working against turbo setup???
ur tuner was right about not wanting the longer duration, but i couldn't give you an answer as to wether or not that's whats causing a flat spot. could be, but also couldn't be
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Re: n/a cams working against turbo setup???
ur tuner was right about not wanting the longer duration Ummm. When you have that over lap, both sets of valves are open (intake and exhaust). This is good on a N/A motor for that scavenging effect to get exhaust gases out of the motor so fresh air can mix with fuel and combust. However, a boosted motor has air being forced in at a high rate/pressure, so boost goes in and out of the engine before its used. Therefore, over lap isn’t best for boost. Well, thast what my memory tells me...its been a while since I did any research on the subject. I suspect that a good tuner can use the high lift cams in a good way...somehow... |
Re: n/a cams working against turbo setup???
Originally Posted by kablammyman
Agreed. Let me see if I can explain this in a few words correctly....
Ummm. When you have that over lap, both sets of valves are open (intake and exhaust). This is good on a N/A motor for that scavenging effect to get exhaust gases out of the motor so fresh air can mix with fuel and combust. However, a boosted motor has air being forced in at a high rate/pressure, so boost goes in and out of the engine before its used. Therefore, over lap isn’t best for boost. Well, thast what my memory tells me...its been a while since I did any research on the subject. I suspect that a good tuner can use the high lift cams in a good way...somehow... |
Re: n/a cams working against turbo setup???
What a load of crap. Overlap is desireable for high revving small displacement turbo engines, period. Compare intake to exhaust pressure sometime... it's blowers that don't like overlap. :1
To the original poster: You are running a faggot 7 psi. It is impossibly to make any worthwhile amount of power from a B16 off of a faggot 7 psi, regardless of how many millions of dollars you spend on camshafts. Turn the boost up, rev to 9K, and prepare to be very happy with your NA cams in the 350+ whp range. |
Re: n/a cams working against turbo setup???
too much overlap is going to let pressurized air fuel mixture escape through the exhaust period.
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Re: n/a cams working against turbo setup???
Originally Posted by z1guy
too much overlap is going to let pressurized air fuel mixture escape through the exhaust period.
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Re: n/a cams working against turbo setup???
rite i undersy=tand wot you guys r saying now
so wots my remmedy? i aint turning the boost up till end of the year that time ill have a built block so you think i should give the skunk2 turbo cams a go? |
Re: n/a cams working against turbo setup???
Originally Posted by Joseph Davis
In a turbo setup with high turbine pressure? Typically 2:1 pressure ratio, unless the engine/setup is really efficient? You sure you don't want to think rethink that?
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Re: n/a cams working against turbo setup???
Originally Posted by Joseph Davis
What a load of crap. Overlap is desireable for high revving small displacement turbo engines, period. Compare intake to exhaust pressure sometime... it's blowers that don't like overlap. :1
To the original poster: You are running a faggot 7 psi. It is impossibly to make any worthwhile amount of power from a B16 off of a faggot 7 psi, regardless of how many millions of dollars you spend on camshafts. Turn the boost up, rev to 9K, and prepare to be very happy with your NA cams in the 350+ whp range. In fact, here is what Corky Bell says about the topic. Pg 163 Camshafts: Make no mistake in the fact that turbo performance cams are very different from atmospheric performance cams. The characteristics of long duration and high overlap for atom cams are unwelcome in a turbo system. The street turbo, which is generally small, operates with exhaust manifold pressure somewhat higher than intake boost pressure. This situation, when presented with long-duration high-overlap cams, creates a huge amount of reversion. Thus, the “turbo cam” tends to become a low-duration, very limited overlap cam. RULE: Its hard to find a turbo cam that works better than the stock item. |
Re: n/a cams working against turbo setup???
OH NOs
Corky's back for more :3 |
Re: n/a cams working against turbo setup???
Originally Posted by egVTI
so you think i should give the skunk2 turbo cams a go?
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Re: n/a cams working against turbo setup???
Correct, reversion != blowtrhough.
And, when you get a setup that is mucho bukkake'd so that intake pressure starts to exceed exhaust pressure, damn if the engines don't like overlap again. Blowing a little intake charge out the exhaust valve is a good thing... anyone care to guess why? BBKA, the only turbo cams I've ever dealt with are Speedy's Web billets for LS, and Rocket M21/M20 combo... the Webs were night and day difference, whereas the Rockets like less fuel below 7500 and 5-6% more fuel 7500-9500 ! |
Re: n/a cams working against turbo setup???
just get ITR cams or crower cams! :P ive heard crower cams are better than skunk2 or so.. the powerband with those cams is almost complete..
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Re: n/a cams working against turbo setup???
Not that you guys are probably talking single cams or anything
But Im running a Delta 272 regrind in the built A6 and theres quite a noticeable difference in where the powerband sits and when the torque is felt over the stock si cam i was running. Idles like a ---- though |
Re: n/a cams working against turbo setup???
Originally Posted by Joseph Davis
Correct, reversion != blowtrhough.
And, when you get a setup that is mucho bukkake'd so that intake pressure starts to exceed exhaust pressure, damn if the engines don't like overlap again. Blowing a little intake charge out the exhaust valve is a good thing... anyone care to guess why? BBKA, the only turbo cams I've ever dealt with are Speedy's Web billets for LS, and Rocket M21/M20 combo... the Webs were night and day difference, whereas the Rockets like less fuel below 7500 and 5-6% more fuel 7500-9500 ! |
Re: n/a cams working against turbo setup???
Cools intake valves superheated by combustion too!
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Re: n/a cams working against turbo setup???
Originally Posted by Walter
just get ITR cams or crower cams! :P ive heard crower cams are better than skunk2 or so.. the powerband with those cams is almost complete..
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Re: n/a cams working against turbo setup???
so if i decide to go boost on my gsr should i get rid of my M24's?
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Re: n/a cams working against turbo setup???
Are you shooting for >500?
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Re: n/a cams working against turbo setup???
probly not
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