custom grind roller cam question...

[street6]

Recently bought a (low mile) built 109 long block with stock compression je's, race ported iron heads, and a custom grind roller cam. The motor was built by a reputable buick shop and I was provided with the build sheet. the custom ground cam specs look rather uncommon to me which are: hyd roller 205int./222exh., lobe separation 108, degree intake lobe 104, cam lift 323int.,and 345exh. (so with 1.55 roller rockers I figure 500 int. valve lift and 534 exh. valve lift).

Intake opens BTDC @ -2 degrees
Intake closes ABDC @ 27 degrees
Exhaust opens BBDC @ 42 degrees
Exhaust closes ATDC @ -2 degrees

With the exhaust duration (222), and valve lift (534) being sooo much bigger than the intake is it best to swap out this cam with say a roller 210/215 or 206/206? The builder advised me this cam grind is used for street applications and has much more torque than hp. Also mentioned that this cam has a steady power curve as opposed to a peaking power curve. I currently run a fmic, 60lb injectors, 3.5 maf, alky, turbonetics te-60 (63 exhaust housing), thdp, and a pat's 3200 10'' converter. Looking for something in the 10.50's range. After reading several posts on boost pressure and exhaust pressure (exhaust pressure usually being 2X boost pressure it has me wondering. Any suggestions would be appreciated.

 

[49-blues]

you better check your math-with a lift of only 325 or so-you will never get a .500" from just .05 ratio over stock of about 150 ratio.

 

[johnplogii]

I ran a very similar (208/224) profile for years. Mine was a flat tappet with less lift, but I think you will be fine. Of coarse you will need a bigger turbo to run 10.50's.

John

 

[street6]

John,

What set up were u running with the 208/224 cam? Turbo? boost? What kind of power curve? Was it indeed a heavy torque cam? Any et times or dyno numbers?

Sorry, but after all the reading I did regarding boost pressure vs. exhaust back pressure I am puzzled why a cam would be split with such an advantage duration on the exhaust side considering the back pressure (exhaust side) is usually 2x the boost pressure and would escape out of the exhaust valve quicker.

I guess everyone has a different theory.
Oh, and BTW how do you obtain valve lift? I was multiplying advertised cam lobe lift by my rocker ratio to get 500 lift on the intake valve (323 x 1.55= 500).

thanks.

 

[bison]

108 lobe seperation doesnt make sense to me on an low rpm iron head application. You could go with a smaller exhaust duration and more degrees seperation and drastically increase low engine speed performance and drivability. You will need at least a 3600 stall for that to work ok. That is not a street grind imo. Ask him to show you proof of performance with that cam on a 231. .500/.534 is correct for 1.55. Thats very similar to a cam that i will be running with a race ported set of GN1's that will make power to 6500. Except ill have more intake duration a little more lift and more lobe seperation. I will still be advancing the cam about 2 degrees.

 

[bison]

you better check your math-with a lift of only 325 or so-you will never get a .500" from just .05 ratio over stock of about 150 ratio.

Stock ratio is advertised at 1.55. So you multiply the ratio times the lobe lift to get the theoretical valve lift. Its actually less than the math in a hydraulic application

 

[johnplogii]

I was running the 208/224 cam until this winter. TE67 turbo usually at 25-26 psi. No dyno sheets but I ran 10 teens at 132+mph. I have no idea of the lobe seperation on my cam, I bought it 10 years ago and lost the cam card a long time ago. I do know it has .420/.465 lift with the stock rocker arm ratio. I finally have decided to go roller cam. I will say on my combo I could have used more intake lift/duration, but it did what it did & made pretty good power.

John

 

[street6]

John,

Just got a little more info on the cam. Do u recall what converter/ or stall speed you were running with the 208/224 cam, and te67 turbo? I'm trying to determine if I will be able to run my current Pats performance 3200 L/U converter.

Thanx, Kevin.

 

[johnplogii]

I ran an Art Carr n/l "n" stall which stall at 3600-3800, then I switched to a PTC n/l which is rated at around 3500. Are you going to stick with the 60mm turbo or go bigger?

John

 

[street6]

For now I was just gonna use my current te60 (since it's basically new) on the new built block however I am not sure if my current Pat's 3200 L/U tc will be sufficient considering the built block has the 205/222 cam. I did not want to go with too large of a tc because my car is mostly driven on the street. I also would like to retain the L/U. I was hoping the te60 would get me into the high 10's with the Pat's 3200 L/U. What cha think, is the te60 enough?

Another concern is that I don't know if this cam and head combo were designed to make hp & torque at a higher rpm levels. Bison mentioned he will be running a similar cam which makes power up to 6500 rpm. With your 208/224 & te67 combo, what were your shift points running 10 teens?

Kevin

 

[street6]

anything?

 

[jasjamz]

anything?

Search of fastest TE 60 in the turbo and related parts section....
http://www.turbobuick.com/forums/turbos-turbo-related-parts/230808-fastest-pt54-60mm-pass.html

HTH

 

[johnplogii]

With your 208/224 & te67 combo, what were your shift points running 10 teens?

Kevin

5500 on the 1-2, 6000 on the 2-3.

John

 

[bison]

For now I was just gonna use my current te60 (since it's basically new) on the new built block however I am not sure if my current Pat's 3200 L/U tc will be sufficient considering the built block has the 205/222 cam. I did not want to go with too large of a tc because my car is mostly driven on the street. I also would like to retain the L/U. I was hoping the te60 would get me into the high 10's with the Pat's 3200 L/U. What cha think, is the te60 enough?

Another concern is that I don't know if this cam and head combo were designed to make hp & torque at a higher rpm levels. Bison mentioned he will be running a similar cam which makes power up to 6500 rpm. With your 208/224 & te67 combo, what were your shift points running 10 teens?

Kevin

Ill be running the 224 with 108 degrees lobe seperation and GN1 race ported heads and 4 bolt turbo most likely with a GTS exhaust. If iron headed and 3 bolt Q trim i woudlnt expect an engine to go much more than 6000 and make decent power. You will need good springs to make good power with a cam like that. I plan on shifting at around 6400.

 

[street6]

Thanx for the info.