C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

L98 Cam.... Which one?

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Old 05-14-2009, 09:38 PM
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Roc87
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Default L98 Cam.... Which one?

I know this isn't C4 related directly, but close

The 88 GTA L98 that was in my elcamino had a blown headgasket. I've pulled the motor, had it bored .030, new flat-top pistons, crank turned 10/10, world products Pro-torque heads (I think that's them, they are Pro something or other) 1.94/1.6 valves 64cc chambers, mild port/polish. Also have a port matched edelbrock TPI base and edelbrock runners. Using 24# injectors. I'm this far into it and was going to leave cam selection to the builder, but he picked an "upgrade" over what the cam would have been for an '87 el camino. Cam he picked out was nearly identical to a stock 88 L98 Cam. I don't really want to purchase a stall converter, and it still has to pass the sniffer emissions test (No visual, so I don't have the smog pump or AIR injection, but do have dual cats) Narrowed it down to the OE '92 Firehawk Cam, and the GM performanceparts cam that was in the ZZ3. If it matters, I have a 3.42 rear gear.
Specs:
SLP .05" duration 214/224, 1.5:1 lift .470/.490, 115 LSA
GM .05" duration 208/221, 1.5:1 lift .474/.510, 112 LSA
Even with the edelbrock stuff, I figure it will be out of breath by 5500, Any help greatly appreciated.
Old 05-14-2009, 11:07 PM
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GREGGPENN
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Of the two you list, I vote for the 214/224 cam -- especially with Edelbrock intake. Intake duration is very important for lt runners. And, it's no where near too big for a 5500 rpm motor.

Last edited by GREGGPENN; 05-14-2009 at 11:11 PM.
Old 05-14-2009, 11:55 PM
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ChopperKingpin
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Either cam will be a decent choice, but you should choose depending on how you want your power delivered. Low-end, or high-end?

The SLP cam will give you a broader, fatter torque curve, and will be a little easier on your tune, since I'm assuming you are running a stock ECM. This is due to the wider LSA, which really is one of the most important things to consider when selecting a cam. This is especially true in a computer controlled car.

The GM cam will give you better overall HP numbers, and will work with slightly lower compression than the other due to the shorter duration, which helps build cylinder pressure. However, 112 LSA is about the 'ragged edge' when using a stock ECM or even a mild tune. (speaking L98, anyway...LSx with a good tune can easily pull off 107 LSA, but that's for another thread...)

I just ordered COMP Xtreme Energy # CL12-268-4 from Summit. It specs out at: 224/230 @ .050", .479"/.480", 114 LSA. This will be decent for now with stock L98 heads, but will really see life with some AFR 190cc heads that are waiting in the wings.
Old 05-15-2009, 12:07 AM
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Roc87
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Thanks guys, I was kindof leaning towards the SLP because of the LSA and the larger duration #'s, and yeah, still running a stock ecm with a tune from TPIChips.com. That Comp cam you listed ChopperKingPin also sounds like it may be a good choice. I use the elky as a DD, and to haul my motorcycle around or tow a trailer to the landfill, not looking for a race car, but something fun on the streets.
Old 05-15-2009, 02:15 AM
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Originally Posted by ChopperKingpin
The GM cam will give you better overall HP numbers, and will work with slightly lower compression than the other due to the shorter duration, which helps build cylinder pressure.
Which means the GM cam will build better low-end torque. The SLP cam should provide better top-end HP -- especially with the extra LSA and duration.

For pulling/towing the GM cam's probably best -- because of the cylinder pressure/torque issue. It will definitely feel stronger at the lower-end. Don't consider a 224/230 cam for this same reason.

I'm betting on the duration vs LSA thing being a wash for mid-range. Hard to tell the difference there (but I'd still bet on the SLP cam for timed runs).

BTW: When you do the tune, make sure you tell them whether your 24# injectors are SVOs (FORD-pressure-rated) or not. (If they are, they flow closer to 25.5.)

Last edited by GREGGPENN; 05-15-2009 at 02:18 AM.
Old 05-15-2009, 02:31 AM
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Originally Posted by GREGGPENN
BTW: When you do the tune, make sure you tell them whether your 24# injectors are SVOs (FORD-pressure-rated) or not. (If they are, they flow closer to 25.5.)
Didn't know that, thanks!

You think the GM cam will still pull alright to 5500? BTW, I'm using crane 1.6 roller tip rockers.
Old 05-15-2009, 10:14 AM
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cv67
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Either one will work fine and idle like a stocker .

Used the Lunati Voodoo(trying to remember the #, 256???) 213/219 cam on a 350 Iroc, similar build asyours and builds great torque everywhere from idle on up. Idles smooth as silk,passes emissionis easily..
Old 05-15-2009, 11:27 AM
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Calderone
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Here are the specs for you to compare
How bout the Hotcam ????
The GM cam you choose its the ZZ4 that's the one i have and im very happy with it.

Stock L98 cam
Duration @ .050", 202/207
Lift: .413/.428 ,
114.5 LSA

ZZ4 cam :
Duration @.050 208/221
Lift: .474/.510
112 LSA
1500-5500 rpm range

Hotcam
Duration @ .050", 218/228
Lift: .525/.525 ,
112 LSA
Old 05-15-2009, 03:04 PM
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Roc87
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Really appreciate the help, picked out this one;

209/217, .465"/.485" 112LSA

Will let you all know how it runs after Memorial Day weekend.
Old 05-15-2009, 03:11 PM
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Bet it works out just fine, good to see somethign different being used than all the typical stuff.
Old 05-15-2009, 04:31 PM
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go to 3rdgen.org

They are serious TPI fans.

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