HSR Dyno
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
hi larry,
this is the cam im going to go for with my new 8 t/b intake
#07-467-8
comp cam hydraulic roller cam,
242 intake,248 exhaust duration @ .50 "
292 intake,300 exhaust advanced duration,
584/579 lift running 1.6 ratio rockers
113 lobe seperation
rev range 2,200 - 6,400 rpm.
still quite agreesive cam i reackon.
cheers
shae
this is the cam im going to go for with my new 8 t/b intake
#07-467-8
comp cam hydraulic roller cam,
242 intake,248 exhaust duration @ .50 "
292 intake,300 exhaust advanced duration,
584/579 lift running 1.6 ratio rockers
113 lobe seperation
rev range 2,200 - 6,400 rpm.
still quite agreesive cam i reackon.
cheers
shae
Are you sure about those numbers. I'm running the XFI 07-467-8 and Comp's site and my cam card show 230/236 @.050.
Is there more than one 07-467-8?
Jake
Pro
Joined: Jun 2007
Posts: 577
Likes: 0
From: the best car on earth ,vettes are best
hi jake,
sorry mate, i made a mistake with the part #,s.
the cam specs i mentioned is a # xfi 08-468-8 it comes with a small base circle for stroker crank install up grades as told to me by comp cam tech department two days ago.
a xfi 07-467-8 is a 230/236 @ .50 " like you have is rite.
cheers
shae
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Several years ago, a guy, (last names Jones) who use to work at Extrude Hone told me that from his experience in flowing intakes and heads, the intake manifold has to flow significantly MORE than the cylinder heads. This is needed so that the intake does not present a flow restriction to the heads.
He went on to tell me that if the intake manifold does not flow significantly more than the cylinder the heads the heads will NOT flow the numbers they generate on the flow bench.
To put it another way, if you have a set of heads that flow, say, 300 CFM at a certain valve lift, they will not flow that amount unless the intake flows much more than 300 CFM.
I recently read an article in one of the mags that provided a percentage number to that. The article said the intake must flow at least 10% more than the heads flow. It's the only time I've seen, in a mag article, a percentage applied. So those 300 CFM heads will need an intake that flows at least 330 CFM. Jones things the percentage would be closer to 20%. So, doing the math, those 300 CFM heads would need an intake that flows at least 360 CFM.
When Jones ported a friend's Mini-Ram, he had to cut it open, port it internally and re-weld it a few times to improve the flow up to close to 400 CFMs. That was needed because to 15 degree ported Brodix heads flowed so well that Mini-Ram had to be radically ported so as not to be a restriction to the head flow. The first couple of times was to boost the flow and then to eliminate the turbulance that developed from the porting.
Could be that your intake just can't flow enough to support the heads and that just changing cams won't give any improvement.
Jake
He went on to tell me that if the intake manifold does not flow significantly more than the cylinder the heads the heads will NOT flow the numbers they generate on the flow bench.
To put it another way, if you have a set of heads that flow, say, 300 CFM at a certain valve lift, they will not flow that amount unless the intake flows much more than 300 CFM.
I recently read an article in one of the mags that provided a percentage number to that. The article said the intake must flow at least 10% more than the heads flow. It's the only time I've seen, in a mag article, a percentage applied. So those 300 CFM heads will need an intake that flows at least 330 CFM. Jones things the percentage would be closer to 20%. So, doing the math, those 300 CFM heads would need an intake that flows at least 360 CFM.
When Jones ported a friend's Mini-Ram, he had to cut it open, port it internally and re-weld it a few times to improve the flow up to close to 400 CFMs. That was needed because to 15 degree ported Brodix heads flowed so well that Mini-Ram had to be radically ported so as not to be a restriction to the head flow. The first couple of times was to boost the flow and then to eliminate the turbulance that developed from the porting.
Could be that your intake just can't flow enough to support the heads and that just changing cams won't give any improvement.
Jake
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
I am in the process of pulling engine,,,,, I am going to have it boiled and honed and then put it back together with all new rings and bearings,,and ,,(drum roll),,, a new cam.
The current Hyd-Roller cam (233/233, 284-289 w/.576 lift) is extremely well mannered and really, a great street cam.... my Dynamic CR is @ 8.5and I loose @ 1.050" of stroke due to the valve timing.
http://www.empirenet.com/pkelley2/DynamicCR.html
I like the TQ I have and probably would not mind having more TQ and the same HP.
Bullet will grind me a Hyd-Roller 238-242, 292-300 with .595" lift,,, but I will loose a small amount more of sweep volume
I know a lot of people would go with a SR but I just dont want to mess with the yearly lash adjustment.
Any body running an similar of larger Hyd-roller? If so do you have decent vacuum?
I am no cam expert so I would appreciate any thoughts from you guys with actual cam expereinces...,
The current Hyd-Roller cam (233/233, 284-289 w/.576 lift) is extremely well mannered and really, a great street cam.... my Dynamic CR is @ 8.5and I loose @ 1.050" of stroke due to the valve timing.
http://www.empirenet.com/pkelley2/DynamicCR.html
I like the TQ I have and probably would not mind having more TQ and the same HP.
Bullet will grind me a Hyd-Roller 238-242, 292-300 with .595" lift,,, but I will loose a small amount more of sweep volume
I know a lot of people would go with a SR but I just dont want to mess with the yearly lash adjustment.
Any body running an similar of larger Hyd-roller? If so do you have decent vacuum?
I am no cam expert so I would appreciate any thoughts from you guys with actual cam expereinces...,
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
No cam expert, but I have a similar amount of duration. Mine is a 396ci. w/236 in.242ex. @50 114lsa lift iand is a tick over .600 billet H.R. with 1.6 rockers. The vac. is pretty good approx. 14 at idle in at 1k rpm. (55kpa MAP). On the dyno aside from break-in they took 3 pulls. The last pull was 537chp and 490 tq. (other pulls had higher tq. lower hp.). There is no problem here w/driveability, and a reasonably smooth idlea. (could have probably gone a tick bigger duration).
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Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
No cam expert, but I have a similar amount of duration. Mine is a 396ci. w/236 in.242ex. @50 114lsa lift iand is a tick over .600 billet H.R. with 1.6 rockers. The vac. is pretty good approx. 14 at idle in at 1k rpm. (55kpa MAP). On the dyno aside from break-in they took 3 pulls. The last pull was 537chp and 490 tq. (other pulls had higher tq. lower hp.). There is no problem here w/driveability, and a reasonably smooth idlea. (could have probably gone a tick bigger duration).
Is yours a custom grind?
