236/250 cam

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03-20-2017, 01:40 PM

#21

Darth_V8r

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Quote:

Originally Posted by JakeFusion

MSD short runner you are thinking? 48 IVC with those? Or 50? If that's the case, the original cam may work. Still a dog until you get to 6k... especially if stock 9.5:1 CR with only 328 cubes.

Yeah, you treed me. I was typing a thesis...

For his displacement, I doubt the MSD would help. I'd be in the 46 degree range with a single plane intake I think. Or just stick with 43 degrees like most and keep the regular intake stuff, etc, until ready to build it up more.

And gonna need to mill the heads or it'll just be lazy, regardless of cam selection.

IMO, that original cam was too big unless 12:1 compression and alcohol for fuel.

Edit - easy to spend someone else's money...

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03-20-2017, 01:57 PM

#22

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Quote:

Originally Posted by brdgcrs

So I called Thompson motorsports and bought a can based on there sugestions. Just want some more opinions because I'm kind of scared lol.
I have a 98 camaro that I have completely gutted and I'm puting a 5.3l lm7 in it. The cam I have is a 236/250. Will I have piston to valve clearance issues or will I be Okay? It's a race only car and won't ever see the street again. It's getting a healthy dose of nitrous as well. Not sure how much yet but I'm starting at 200 and going up from there

What are the rest of the specs? Whether it will fit or not is all about the valve timing. Also, what intake manifold is on the car?

If you tell me the lobe separation angle and the intake centerline (or how much advance) I can estimate if it will fit.

As for performance in an LM7 with nitrous, if the lobe centers are correct and it will fit, it could be good on a 200 shot.

For example, if it is 236/250 on 115+5, it would have valve events of:

IVO(intake valve open) 8 degrees BTDC(before top dead center) at .050"
IVC(intake valve close) 48 degrees ABDC(after bottom dead center) at .050"
EVO(exhaust valve open) 65 degrees BBDC(before bottom dead center) at .050"
EVC(exhaust valve close) 5 degrees ATDC(after top dead center) at .050"

236/250 is a pretty big camshaft for a street driven, low compression 5.3 liter engine. Unless it has a 5000+ RPM 8" stall converter in it and 4.56 gears, it will be a dog on motor. However, once you spray 200 horsepower of nitrous, the results can be quite different.

Nitrous has the virtue of supplying massive torque. So much so that often times racers have to pull timing and or run a progressive nitrous controller to reduce power on the launch in order to get traction or avoid wheelstands. In cases like this, choosing a camshaft that is focuses on the very top end of the RPM range can be a smart choice. However, the downside to this strategy is that the car will likely be a dog without nitrous.

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03-20-2017, 02:48 PM

#23

brdgcrs

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Let's forget that I have this cam already. I have a complete gasket kit, mls head gaskets, electric water pump, alternator only belt setup, billet timing set, melling oil pump, ls6 intake and an lm7.

I want to know which cam is best for a 3200 nitrous stall in an lm7. I will have nx send me a nitrous kit next month.

Car is only going to be on an 1/8th mile track.

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03-20-2017, 04:38 PM

#24

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Quote:

Originally Posted by brdgcrs

For what you are doing, I might like to make you something custom. I like a 226/236 on a 113.5 lobe center angle with +4.5 advance with .621" intake lift and a .604" exhaust lift. It will run great on motor and handle a 200 shot no problem. It will drive nice, but still have a little lope at idle.

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03-20-2017, 08:53 PM

#25

JakeFusion

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Quote:

Originally Posted by JakeFusion

I'd do something like a 222/234 112+3 or so for good midrange power while still being happy on the gas.

Or a little more top end would be a 224/236 113+3.

Both would drive well, thump a bit at idle, and make good usable power with the 3200 stall in the 5.3 but pick a ton on nitrous. The added exhaust duration would carry the power after peak pretty well NA.

Hmm that 226/236 113.5 seems a lot like something I recommended earlier.