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New big cam, lots more turbo lag??


big-phil

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I did have the cam in the right hole for several runs with the big cam. It pulled very hard and nice. The last installation of the head/cam I got it off by 2 teeth. I put the motor to TDC, checked the timing mark on the cam gear, and the notch on the gear retainer was off. Thats how I realized it was off.

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umm.. im running a .488 lift and 260 duration (in/ex) cam on my car..

 

Phil we have very very similar specs.. and I also have a 2mm metal headgasket...

 

I didnt need to adjust the cam sprocket at all.. only thing I did was slide in the new cam, new springs and adjusted properly.. and changed some tuning.

 

I didnt even bother changing the timing.. and I have great power and the turbo gets full boost at 3,600 RPM. Maybe the altitude makes a difference on spool or something.. but I love my setup right now.

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umm.. im running a .488 lift and 260 duration (in/ex) cam on my car..

 

Phil we have very very similar specs.. and I also have a 2mm metal headgasket...

 

I didnt need to adjust the cam sprocket at all.. only thing I did was slide in the new cam, new springs and adjusted properly.. and changed some tuning.

 

I didnt even bother changing the timing.. and I have great power and the turbo gets full boost at 3,600 RPM. Maybe the altitude makes a difference on spool or something.. but I love my setup right now.

whats your vac at idle. I was waiting for you to chime in. I remember you saying you got a biger cam and our setup looks to be kinda close. Does your car have good off boost power?

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I think your timing is just right. Long duration cams need more timing at idle or else the exhaust will glow orange. They also need lower a/f ratios at idle because of the added over lap. FYI, stock turbo timing is 24 degrees.

 

It is real hard to change the LSA on a regrind cam. However, the extra thick pads (0.230) for a 290/280 cam does indicate something to the lsa was done.

 

Your new cam is very big for a street turbo and does not have nearly enough LSA (112). A cam that big needs around 118 or 120 LSA. You could easily run 8.3:1 cr with that long duration. The amount of vacuum drop at idle with your new cam seems about right to me.

 

A turbo with a lot of valve over lap makes a very narrow power band.

 

A use a MSA stage 1 turbo cam 260/250 with 114 LSA, and it pulls hard to 6500 rpms. Boost starts at 3000 rpm (5 psi) and hit full boost by 3500 but I think the lag is mainly due to a free flowing hot side. Maybe a stage 2 from MSA is what you need.

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I agree with everyone's feedback on your cam selection Phil. Too radical for the street. I am using Web Cam's Turbo grind for my L30ET, I did alot of research before my final selection. This Web cam (which is a brand new billet) does not have alot of duration but 488 of lift, which is what you want, keep those valves opened longer for the forced air to make it through for a longer combustion reaction.

 

Turbo cars need more lift and not so much duration.

 

Yasin

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Thanks guys. chris240zturbo is telling me he thinks that I was off maybe 1 link in the cam chain the whole time I had that big cam in?? Its killing me to think that!

 

I do have the head swap down to 3 hrs. But I'll wait until I port the head, and I'm going to make an intake for my 90mm TB I just happen to have lying around.:eek:

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  • 9 months later...

I'm pretty sure Big Phil's ultimate goal is somewhere around 60-100 lbs of boost at all times (even while sleeping). I think he was just mis-interpreting the lag for the time it takes for light waves to be perceived by the brain. When your accelerating that fast the visual perception of time seems to slow down as the light waves stretch out. Leave it to Phil to not take that in account. duh.......

 

His motor is really strong, the whole thing is made of metal....

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Sounds to me like the intake manifold is holding him back. A lot. Throw that bumpstick back in there and recheck the timing! :-) If it's still a bit doggy start getting your materials together for an intake manifold.

 

I wanna see another vid like his calling off the speeds on the highway. Classic.

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( as I take a fresh dip of Copenhagen ) I bought a lone wolf intake from 280zforce and a ported head here locally. After I get the intake I'll put that cam into the ported head and try it out again.

 

this cam is:

intake 490 lift 290 dur.

exhaust 480 lift 280 dur.

overlap 61

 

Chris's cam is:

intake 490 lift 276 dur.

exhaust 480 lift 268 dur.

overlap 44? (forty something)

 

so if the low end suffers still I'm going to order Chris's cam specs from Isky

 

by the way this cam pulled great up top

 

the ported head I got came with a cam:

 

intake 460 lift 270 dur.

exhaust 460 lift 260 dur.

overlap 41

 

But I broke the cam in two when putting it in the head:roll:

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How to tell if you have a good cam or a bad cam

Step one: Raise camshaft to an elevated level

Step two: Drop camshaft onto concrete surface from elevated level

Step three: If camshaft shatters, Congrats! It's a good cam! If not, then toss it, it's no good.

 

I remmeber my dad told me that for VW's if the cam was good, they would break if you were to drop them, but if they were bad, they wouldn't break or crack. I suppose because the metal is so hard it becomes extremely brittle, where a bad cams metal is much softer and less brittle.

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How to tell if you have a good cam or a bad cam

Step one: Raise camshaft to an elevated level

Step two: Drop camshaft onto concrete surface from elevated level

Step three: If camshaft shatters, Congrats! It's a good cam! If not, then toss it, it's no good.

 

I remmeber my dad told me that for VW's if the cam was good, they would break if you were to drop them, but if they were bad, they wouldn't break or crack. I suppose because the metal is so hard it becomes extremely brittle, where a bad cams metal is much softer and less brittle.

lol, I guess that WAS a good cam

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I had a regrind break earlier this year...damnit! We suspect a latent failure in the core we used since the cam towers were spot on, no galling, and the head was flat/flat top and bottom. Damnedest thing, Ive seen it happen on warped heads before, and where the cam towers seized for whatever reason... But this didn't have any of the 'normal' signs for something taking the cam out with it...

 

When was the last time you heard of someone magnafluxing a cam? I will from now on, before putting a $100 Regrind into it!

 

Damn, it ran well with that cam, too!

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