Cam crunch time

[Don W.]

I,m prolly wearing you guys out with my questions, but soon it will be crunch time on picking a cam for my rebuild. Current specs are: stock crank (0.010 - 0.010), 4 bolt mains, Eagle rods, Vortec heads, pistons not bought yet. Engine will be balanced. I have a set of new 50# injs but it seems no one likes those anymore and wants 60#'s. Turbo is undecided at the moment, but prolly looking at a modified 20g. Since, IMO, a cam is the key to everyting, custom is an option.

Once everything is decided a new TC will be in the mix on a built 700.

My goal is a driver that runs in the low 12's on, hopefully, something less than 20# of boost. Anyway, cam thoughts appreciated.

Thanks all !!

 

[It's just a six]

Re: Cam crunch time

Depends on if you want to still pass smog legally???

I would say not going much over 204 degrees duration @ .050. Get a wide lobe center of 115 or so.

 

[berzerker]

Re: Cam crunch time

comp 412 cam has gotten trucks into the low 11's

 

[Don W.]

Re: Cam crunch time

I will know for sure in a few weeks on the smog question. Plan is that problem is over.

 

[R&C_RallySyTy]

Re: Cam crunch time

I don't know much about cams, but take advice from people here. I have a really strange cam in mine, makes it hard to tune. Not going to hijack your thread and talk about my cam, but good luck. Like someone else said, a comp 412 seems to work. Don't really know what else others run.

 

[blk00z28]

Re: Cam crunch time

What turbo are you running?

 

[midnightbluS10]

Re: Cam crunch time

What turbo are you running?

Don said:

Turbo is undecided at the moment, but prolly looking at a modified 20g

 

[sy#2716]

Re: Cam crunch time

412 low 11's, 415 low 10's, and 422 high 9's

 

[TYTILIDIE]

Re: Cam crunch time

I'd check out Campbell. Did you see his post about dynoing 593 with a modded 20g? I'd probably copy the whole build.

 

[Windedv6]

Re: Cam crunch time

I will throw in my 4 cents in…

Back in 2001, I ran my Typhoon into the high 12s with the 412 cam, 1.5 rockers, stock injectors and a PTE 44 turbo. My Ty is overweight by about 100 lbs as I had it fully Dynamated for car audio purposes years ago and it was to hard to remove it (a stock Ty should be at least 10th faster than mine and a Sy about six 1/10ths faster). Under this build (stock internals and stock heads), the stock injectors max out at 100% DC (duty cycle). I cracked a couple piston ring lands by running it on the lean side.

I rebuilt the motor using a bowtie block, vortec heads, eagle rods and SRP pistons. I changed turbos to a PTE 63E and kept the 412 cam with 1.5 rockers. I also put in 50 lb injectors with a tuned 50 lb chip. With this setup I ran consistent 12.0s and pushed it to a best of 11.8s. The limiting factor was the intakes temps with the stock style intercooler.

I then re-modded it and installed an A2A intercooler, 75 lb injectors, a PTE 70 stealth turbo and a FAST engine management system. I ran consistent 11.4s. The 412 cam and the 1.5 rockers were still doing a perfect job with this build. This was the best for street drivability and street performance of all my builds. Many times I wish I would have just left it alone with this build.

A few of years ago I put in a cage, changed the rear suspension, etc, and went with a 72GTQ turbo, a Daytona Dash single plane intake and 84 lb injectors. I ran 10.8s consistently and a best ET of 10.72. This was still with the 412 cam and 1.5 rockers.

I then switched cams to a custom grind thinking I would make a decent improvement, but only bested a 10.61 ET ( vs the 10.72) and lost a lot of low end drivability.

What I am saying is that the 412 cam has a wide range that it can play in and keeps it drivability. The 412 cam spooled the different turbos better than the custom grind. Although the custom can had better top end it suffered on the bottom end and had a longer spool time. This is why the track times were not much different.

One of the top custom cam grinders for turbo motors explained to me that the critical component is the duration and timing of the duration. There is not a need for big lift cams in a force induction motor. The extra lift will not do you any benefit as you have a loaded supply of intake air (boost). Opening the valve any farther than necessary will not gain performance and only cause unneeded valve train wear.

Another advice he gave is on the lobe separation. It seems that everyone thinks that the bigger LS number (112*, 114*, 115*, etc) the better it is for a turbo motor. He said that is a mistake to think that way just because we read or hear of the turbo race guys using those 114*, 115*, 116* LS cams, that it must be the greatest thing for everyone. He explained that running high degree lobe separations will cause higher piston, exhaust valves and exhaust temps, as the exhaust valve closes quicker trapping the intake charge from escaping through the exhaust valve. Allowing some cooler intake air to escape has always been the main stay for NA motors as scavenging headers helps load the cylinder before the exhaust valve closes. This is why you see 110*, 108* LS cams on healthy NA motors.

With a forced induction motor the theory is that with a forced supply of air you can close the exhaust valve early thus making more top end power. The price for this is higher temps and slower spooling. The recommendation he gave me was for a lower hp street applications we should be staying with a 112* LS, and with a good A2A intercooler or alky system use a 114* LS cam. Leave the 115*,116*, 117* stuff to the track guys running ice chests.

In my many years of amateur turbo experiences I would have to believe him to be correct as the 412 cam as been a great all around performance cam for me through several motor combinations.

John

 

[jwaller]

Re: Cam crunch time

I've got a custom grind for the vortec's I need to sell. pm me for details

 

[R&C_RallySyTy]

Re: Cam crunch time

I will throw in my 4 cents in…

Back in 2001, I ran my Typhoon into the high 12s with the 412 cam, 1.5 rockers, stock injectors and a PTE 44 turbo. My Ty is overweight by about 100 lbs as I had it fully Dynamated for car audio purposes years ago and it was to hard to remove it (a stock Ty should be at least 10th faster than mine and a Sy about six 1/10ths faster). Under this build (stock internals and stock heads), the stock injectors max out at 100% DC (duty cycle). I cracked a couple piston ring lands by running it on the lean side.

I rebuilt the motor using a bowtie block, vortec heads, eagle rods and SRP pistons. I changed turbos to a PTE 63E and kept the 412 cam with 1.5 rockers. I also put in 50 lb injectors with a tuned 50 lb chip. With this setup I ran consistent 12.0s and pushed it to a best of 11.8s. The limiting factor was the intakes temps with the stock style intercooler.

I then re-modded it and installed an A2A intercooler, 75 lb injectors, a PTE 70 stealth turbo and a FAST engine management system. I ran consistent 11.4s. The 412 cam and the 1.5 rockers were still doing a perfect job with this build. This was the best for street drivability and street performance of all my builds. Many times I wish I would have just left it alone with this build.

A few of years ago I put in a cage, changed the rear suspension, etc, and went with a 72GTQ turbo, a Daytona Dash single plane intake and 84 lb injectors. I ran 10.8s consistently and a best ET of 10.72. This was still with the 412 cam and 1.5 rockers.

I then switched cams to a custom grind thinking I would make a decent improvement, but only bested a 10.61 ET ( vs the 10.72) and lost a lot of low end drivability.

What I am saying is that the 412 cam has a wide range that it can play in and keeps it drivability. The 412 cam spooled the different turbos better than the custom grind. Although the custom can had better top end it suffered on the bottom end and had a longer spool time. This is why the track times were not much different.

One of the top custom cam grinders for turbo motors explained to me that the critical component is the duration and timing of the duration. There is not a need for big lift cams in a force induction motor. The extra lift will not do you any benefit as you have a loaded supply of intake air (boost). Opening the valve any farther than necessary will not gain performance and only cause unneeded valve train wear.

Another advice he gave is on the lobe separation. It seems that everyone thinks that the bigger LS number (112*, 114*, 115*, etc) the better it is for a turbo motor. He said that is a mistake to think that way just because we read or hear of the turbo race guys using those 114*, 115*, 116* LS cams, that it must be the greatest thing for everyone. He explained that running high degree lobe separations will cause higher piston, exhaust valves and exhaust temps, as the exhaust valve closes quicker trapping the intake charge from escaping through the exhaust valve. Allowing some cooler intake air to escape has always been the main stay for NA motors as scavenging headers helps load the cylinder before the exhaust valve closes. This is why you see 110*, 108* LS cams on healthy NA motors.

With a forced induction motor the theory is that with a forced supply of air you can close the exhaust valve early thus making more top end power. The price for this is higher temps and slower spooling. The recommendation he gave me was for a lower hp street applications we should be staying with a 112* LS, and with a good A2A intercooler or alky system use a 114* LS cam. Leave the 115*,116*, 117* stuff to the track guys running ice chests.

In my many years of amateur turbo experiences I would have to believe him to be correct as the 412 cam as been a great all around performance cam for me through several motor combinations.

John

John, very nice post. You learn something new everyday. This makes me want to change my cam. I don't want to hijack this thread but I'm thinking my cam is not working for my setup.

Here is my cam specs:

 

[Don W.]

Re: Cam crunch time

Really appreciate the input guys. The cam info exchanges (call it hijack if you want) are perfectly OK with me. The more info we can swap the better as far as I'm concerned.

PM sent to JWaller

 

[R&C_RallySyTy]

Re: Cam crunch time

Really appreciate the input guys. The cam info exchanges (call it hijack if you want) are perfectly OK with me. The more info we can swap the better as far as I'm concerned.

PM sent to JWaller

Sweet, I agree with you. The more info the better. I think I learn something new every day on here.

 

[blk00z28]

Re: Cam crunch time

Here is my cam specs:

With my 1.6 rockers I have almost exactly .100 more lift then you.:lol:

 

[Windedv6]

Re: Cam crunch time

John, very nice post. You learn something new everyday. This makes me want to change my cam. I don't want to hijack this thread but I'm thinking my cam is not working for my setup.

Here is my cam specs:

What is your build? Your cam setup is is about as aggressive as a comp 422 cam which is more than merited for a stockish build. If you have vortec heads and a larger turbo and an agressive stall 2800 to 3200 this cam should be decent for you.

John

 

[R&C_RallySyTy]

Re: Cam crunch time

What is your build? Your cam setup is is about as aggressive as a comp 422 cam which is more than merited for a stockish build. If you have vortec heads and a larger turbo and an agressive stall 2800 to 3200 this cam should be decent for you.

John

Turbo:
TE45A
66 intake wheel
.63 Prescion exhaust

Engine:
Race Prepped Short Block:
Block bored on precison stand & 2 step torque plate honed
Speed Pro "Plasma" moly piston rings; file fit
Diamond Custom 2618 Forged Custom Pistons
Eagle H beam connecting rods
Federal Mogul Super Duty Alloy Main and Rod Bearings
Federal Mogul cam bearings
Speed Pro double roller timing set
Comp Cams custom grind Xtreme Energy hydaulic roller camshaft
Comp Cams Magnum hydaulic roller lifters
Comp Cams valve springs
Pro Gram Engineering splayed bolt, 4 bolt center caps, convert to 4 bolt main bearing splayed bolt block
ARP coonecting rod bolts, main studs
Degree in cam
Hot Tank block, heads, misc., install new core plugs
Precison ground crankshaft, nitrate treated
Balancing rotating assembly
Align bore main saddles
HD oil pump w/HD driveshaft
Engine Gasket set (includes "GM" head and intake gaskets specific to the Syclone/Typhoon)

Heads and Valve Train
Brodix cylinder heads (Manley pushrod guide plates and screw in studs)
Bowl and Chamber port work
Full competition port work
HD vavle springs matched to camshaft
Comp Cams Magnum Roller tip rocker arm kit, 1.6:1 ratio
ARP head studs
Cylinder head resurfaced

Tranny:
Rebuild Custom Supplied 700R4
Syclone/Typhoon to Street and Strip
Specs for use with lock-up Torq Converter

Persicion Industires 9.5 L/U Torq Converter
Hi-Pro trans Upgrade
Includes billet servos, wide band, beast sunshell? Racing 3-4 Clutch pack, servo CK vavle?
5 pinion planets Front and Rear

Rebuild Transfer Case
Includes new front career, input shaft, planet and chain
Corvette Governor (5200 rpm shift)

Other Stuff:
Set of 50lb Fuel injectors
3 bar map sensor
O2 sensor 3wire
wastegate kit
2end Alky nozzle kit
Exhaust band clamp
EGR block off plate
FAST fuel injection mangement system
fuel injection wire harness
EST Spark Module
Engine Mounts

Things I need yet:
A2A Big IC
I have a crack in one of the pipes, small leak (can hear ticking noise) needs welded
Fix Steering Slop
Tie Rod Ends
Bushing Kit
New Spark Plug Wires
Was told bigger injectors would do me well.
Maybe get the heads cleaned up, was running very rich.
Tuned

 

[turbodig]

Re: Cam crunch time

John, very nice post. You learn something new everyday. This makes me want to change my cam. I don't want to hijack this thread but I'm thinking my cam is not working for my setup.

Here is my cam specs:

This doesn't look like a bad cam at all, to me. I certainly wouldn't go out of my way to change it.

 

[Windedv6]

Re: Cam crunch time

This doesn't look like a bad cam at all, to me. I certainly wouldn't go out of my way to change it.

I am with Dig on this. Your 1.6 rockers give you a .528 lift with a duration that fits well with your bigger head setup. I am assuming that your ported Bordix head numbers are in the 280 cfm range at .500 lift. and intake runner volume around 200cc. Are the chambers open enough to keep your compression in the 8.3 - 8.5 range? If so then your may want to look at a .85 a/r housing or a bigger turbo in general. You have a lot of air volume capabilities with your heads and cam. The exhaust is going to hold you back. Also get some 75# injectors before you lean yourself out. With any decent amout of boost you will be maxing the duty cycle in the 50s. A good rule of thumb is to have your injector duty cycle around 80% at WOTand max boost.

John

 

[R&C_RallySyTy]

Re: Cam crunch time

I am with Dig on this. Your 1.6 rockers give you a .528 lift with a duration that fits well with your bigger head setup. I am assuming that your ported Bordix head numbers are in the 280 cfm range at .500 lift. and intake runner volume around 200cc. Are the chambers open enough to keep your compression in the 8.3 - 8.5 range? If so then your may want to look at a .85 a/r housing or a bigger turbo in general. You have a lot of air volume capabilities with your heads and cam. The exhaust is going to hold you back. Also get some 75# injectors before you lean yourself out. With any decent amout of boost you will be maxing the duty cycle in the 50s. A good rule of thumb is to have your injector duty cycle around 80% at WOTand max boost.

John

Thanks for the info. I'm going to do exactly that when I run into some more money. Right now things are rough. I want to pay back a member here first before I get anything else. I also really need a better IC. Once I get a nice FMIC and injectors, bigger turbo what do you think I will run with my set up?