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Choosing a camshaft.. and how to match a turbo


proxlamus©

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The second cam is an Isky part, this cam is a little more radical, and I would not recommend going past this specification for any turbo L28.

 

ANY Turbo L28 Jeff? I did the gearing checks and I need 28" tires and 650HP+ if limited only to 7500rpm.

 

ANY?

 

LOL

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well holy cow...

 

TEP may not be the best!

 

Ok.. i'm going Zgad's grind.. its dyno proven and everyone has had success except for the small batch of mis-grinds ;)

 

haha thank you guys..

 

JeffP.. your specs are definatly wild! That 2nd cam sounds radical?!

 

Maybe I should specify this car is a daily driver.. so would Zgad's or the Elgin be right up my way? or would the wild cam setup from Isky be too much for a daily driver?

 

 

The second cam is an Isky part, this cam is a little more radical, and I would not recommend going past this specification for any turbo L28.

55 degrees of overlap, .580 lift intake/ .540 lift exhaust lobe center 114, intake opens 31 BTDC exhaust opens 67 ATDC 290 duration intake 270 duration exhaust.

Those two grinds will do just about whatever anyone with a turbo could want. The Elgin cam works very well, the Isky cam is really good, but it more of a topend cam.

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Jeff's car is really sedate and could easily be used in daily driven service. Given he gets 3psi at almost any rpm, the torque below boost threshold is very good making for great drivability. He can better give performance on the Elgin Grind, but as I recall he would break 30mpg during cruising. EFI and Turbos are a great combination!

 

BTW, that is not the "radical" grind from Isky's Turbo Lineup. Ron is like a mad scientist when it comes to Nissan L-Grinds, he has some FAR more radical stuff out there, you just need ask! LOL

 

But like Jeff says...probably not for the street. Hence my admonitioning and chiding Jeff about 'ANY' Turbo Z! LOL

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Prox, I have Jeff's elgin cam on my car. It's no problem for daily driving. The car is very smooth and tractable. The vacuum at idle is about 16in or so. I get a full 22 psi by 3700rpm with my setup. That might be a bit different for someone with a stick shift as I have a loosened up converter.

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Ok new updated list to compare everything side by side

 

Z-gad developed his grind with a noticeable performance boost

Intake 490 lift 276 duration Lift

Exhaust 480 lift 266 duration

114* lobe center

44* overlap

 

Elgin Cam

Intake 480 lift 266 duration

Exhuast 480 lift 266 duration

112* lobe center

48* overlap

intake open was 21 degrees@50 and exhaust I believe if memory serves me correctly 72 degrees.

 

Isky cam

Intake 580 lift 290 duration

Exhuast 540 lift 270 duration

Lobe Center 114*

Overlap 55*

 

MSA Stage I (Schneider)

Intake .460 lift 260 durations lift

Exhuast .440 lift 250 duration

 

 

MSA Stage II (Schneider)

Intake .460 lift 270 durations lift

Exhuast .460 lift 260 duration

 

Schneider Stage III

Intake 488 lift 284 duration

Exhuast 488 lift 270 duration

Lobe 114

 

RaceTep

Intake 480 lift 272 duration

Exhuast 480 lift 274 exhuast

 

 

All of the cam's are very similar except a few minor changes in lift and duration and lobe center ..

EXCEPT the Isky cam.. every cam ranges around 480 lift... then the Isky is 540!?! holy freakn crap...

 

Jeff can you please describe the driving characteristics on that Isky cam?! too me and available cams.. the Isky sounds wicked.. definatly

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I looked for my cam card but cant find it. I believe the duration @ .050 was 255 and 270 or so.

I would not recommend the Isky cam unless you are race only, you will need good fuel for that cam, 87 octane will not cut it with boost.

 

You guys need to realize the @ .050 readings are not that good for a turbo engine. You crack the valve .005 off the seat and you are pushing air into the cylinder under boost, so you really need to have a good handle on the opening and closing points of the intake valve.

I would recommend the Elgin grind for just about any street car. Bernard has the old head and cam from my engine and according to him and his testing that cam pulls him to 7K no problem, and he also can feel the power coming on VERY HARD @ 5K to 6K and that seems to be the peek power point for that cam. I cant give you any info from my engine as the cam timing and valve lash was incorrect, the timing being changed due to the incorrect valve lash.

So you will still get good fuel mileage with the cam, provided you keep your foot out of it.

The thing you need to understand is that you are basically running tow engines, OFF BOOST, or the N/A operation of the engine, and that really is what you need to decide, how much do you want off boost for performance. Then you have the second part of the equation, BOOSTED. There is a VERY big difference between off boost and on boost of ANY engine.

So get the power you want, within reason, off boost and go from there. I would not recommend trying to get 300hp N/A and then trying to boost the engine. A cam that will give you that much power, first of all, it will be making power in the 6-7K rpm range, be soggy on the low end, and innefficient at low rpm,s until you get the induction flowing well at higher rpm's.

So go with a mild cam gerind. Get the lift high, the duration realitively short, and overlap no greater then 50 degrees. That will be your best setup for the L engine with mild porting.

Myself, I went to the extreme, but in doing so, I am now setup to run just about any cam I want without spring bind. Smaller is not an issue for me so I can always roll back the cam specs and do more testing.

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Jeff,

 

In almost all cases, more information is better. Blindly going by advertised duration and not paying any heed to the potential differences in ramp rate (and hence 0.05 duration) is not a particularly intelligent way to select a camshaft for any application.

 

250/270 is a relatively large split for intake/exhaust 0.05 durations I would have thought?

 

Dave

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When I selected the cam I chose to run, I contacted Ron at ISKY cams and explained the engine setup (turbocharged stock longblock with bolt-ons), the turbo I was using (T-66 p-trim with a .58 a/r turbing housing), the RPM band I was looking for (where I had full boost of 20 psi at roughly 4400 rpm's), where I was intending to rev the motor to (7000 ish rpm's), and that I wanted the power band of the cam to match the power band of the turbo (4400+ rpm's). I knew I wanted 114* lobe centers and a staggered intake/exhaust duration with a longer duration on the intake than the exhaust, to speed up the exhaust flow out of the engine to help aid in turbo spool (atleast that was my theory behind staggering the intake and exhaust lift/duration). I am certainly not advocating the cam I chose to everyone, as a turbo motor's power band is somewhat dictated by turbo size and exhaust a/r. I don't think that a stock size turbo would have benefitted from my cam choice, but the large frame turbo certainly did.

just my .02

mike

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Thank you Jeff, Tony and Mike!

 

honestly.. after comparing everything.. I LOVE Mike's cam setup... its a bit more agressive than the Elgin cam specs Jeff posted and more agressive than Schnieders

Do you guys think it would match up my turbo?

 

 

Holset HY35W

Turbine Housing 9 cm2 = 0.65 A/R

Turbine Wheel = 70mm dia (60mm exducer)

Compressor Wheel = 54mm inducer

Choke point = 29psi

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