Turbo Cam for a 200???

Y

yellowstang

Well-known member
I am finally ready to buy a camshaft. I have narrowed it down to about 4…

My new valve train will support .480 lift, but would like to stay around .465"; Picking a 112 LSA.

I like the Clay Smith Cam 274 HSP, Crow 282S, Isky 280, Comp 280.

Can you tell me more about those to help me select the right one? (Intake and exhaust numbers, overlap etc)

I am going to run on my 68 mustang convertible, 200 L6, OZ 2V head, ported and polished, running a Holley 8007(390cfm carb) running a T3 or T4 about 15 psi, intercooled.

I don’t think I would need Rhoads lifters unless I was over 290 on the cam.

I currently am running an Isky 256 cam, 112 LSA with .450 lift

looking forward to hearing from you,
Pete Hornung
aka yellowstang
 
I would say street.

Obvioulsy the combo Cam/Turbo/Intercooler/Oz-2V head/holley 390cfm/5 speed are all related.

Looking for a fun to drive but awesome performance

I am looking for all the turbo recipes that are in work. maybe we can start a spreadsheet

it could list
engine
main bearings
forged pistons - y/n
Head
ignition
cam
turbo
turbine
compressor
intercooled - y/n
intercooler size
iC brand
carb
fuel injection - y/n
Boost
Dyno tune - y/n
HP
TQ
turbo performance - perfect / spools too quickly / boggy
owner
 
yellowstang":2l73ybu5 said:
I would say street.

Obvioulsy the combo Cam/Turbo/Intercooler/Oz-2V head/holley 390cfm/5 speed are all related.

Looking for a fun to drive but awesome performance

turbo performance - perfect / spools too quickly / boggy
owner
Click to expand...

For street application most are looking for quick spool time and most of the boost in by 2000 rpm with power out to 5000 rpm.

Typically a turbo cam with that response has an intake .050" lobe duration not much more that stock.
For a 200 six an intake duration not more than 200* would be recommended along with high valve lift.
The .450" lift range you are looking at is good.

Valve overlap should be minimized with LSAs between 112 and 114.

You may have noticed that some turbo cams actually have less exhaust duration than intake duration.
 
I would talk to bullet cams,the old school thinking of a lot more timing on intake than exhaust may have changed,talk to them.
 
The Isky 256 cam you are presently running has a 202* .050" duration and a 112* LSA.
It may be close to what you need for turbocharging.

A good indication for turbo spool response is where the power band begins.

What RPM does the engine begin to pull with the Isky 256 cam?
 
1. isky 256/256 is a 202/202 @.050, LSA 112 and .450 lift; the spec says 1500-4800.

the choices are
2. clay smith 264/274 is a 214/224 @.050, LSA 112 (or LSA 110) and .441/.450 lift

3. clay smith 274/274 is a 224/224 @.050, LSA 112 (or LSA 110) and .450 lift

4. Crow 280/280 is 214/214@.050, LSA 112 and .442 lift

5. isky 280/280 is a 224/224 @.050, LSA 112 and .465 lift

For a turbo, it would be good if there were 10deg more on exhaust. I have also heard that a LSA 110 may help keeping the exhaust valve cooler than the 112 LSA
 
yellowstang":2dqoz9fw said:
For a turbo, it would be good if there were 10deg more on exhaust. I have also heard that a LSA 110 may help keeping the exhaust valve cooler than the 112 LSA
Click to expand...

The 10 degree more on the exhaust and the tight LSA work for a supercharged engine NOT on a turbo engine!!

Because most turbo systems create more exhaust pressure than boost pressure especially if a stock log type exhaust manifold is used, valve overlap needs to be minimized or else the exhaust gas will cause reversion into the intake ports at low rpm killiing low rpm engine response.
We used a LSA of 116 degrees on our race turbo applications.

Again, the choices you are indicating will work for a supercharger but not for a turbo application on a relatively small displacement engine like a 200 where you are trying to make power from 2000 to 5000 rpm.

The Isky 256 cam is a good place to start.
 
sounds great. I will stay with the Isly 256.

The OZ 2V head is already on and makes great power with a holley 2300 2bbl. I ported and polished the Head.

I am going to get a Holley 8007, 390cfm, progressive 4bbl. I will get the 4bbl adapter plate and then weld it to the OZ manifold.

I am upgrading the radiator to a 24" 3 core. then installing an intercooler in front of that. the IC will be only half as tall as the radiator (12tall x 18 wide). This should keep the engine cool as well as the IC cooling the air charge

I will need to select the turbo next. I have a friend giving me T4.

What's a good match to my set up??
 
Figuring on 15 psi of boost at 5000 rpm, you need a turbo that will deliver 35 lbs/min of air at a pressure ratio of 2.1

Around a 50mm (inducer diameter) turbo rated at 400 hp should get the job done.
Something equivalent to a GT2871R

The turbine housing A/R needs to be around .64 or less for fast spool time.

With the ported head and 15lbs of boost you should be able to make 350hp
 
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