Too Big A Cam?
Thread Starter
Instructor
Joined: Mar 2003
Posts: 176
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From: Holtsville NY
Too Big A Cam?
I am looking to install a cam for maximum street power into a stock LT1
I am looking at these four,
the LT4 Hotcam 219/228 @.05 with .525/.525 on 1.6rrs
the LPE 219 219/219 @.05 with .560/.560 on 1.6rrs
Comp Cams 305 220/230 @.05 with .533/.533 on 1.6rrs
or GTP-3 226/226 @.05 with .534/.534 on 1.6rrs
Are any of these too much cam for the stock motor, I will be uprgading the valve springs, and associated parts and going with Pro Magnum RRs (1.6, non self aligning, 7/16" studs) guideplates, chromemoly pushrods.
I know a ton of people run the Hotcam and get good power, and I hear very good things about the LPE cam, I am looking for the max supportable street driveable power and trying to find my best option.
Thanks for any help and or opinions
I am looking at these four,
the LT4 Hotcam 219/228 @.05 with .525/.525 on 1.6rrs
the LPE 219 219/219 @.05 with .560/.560 on 1.6rrs
Comp Cams 305 220/230 @.05 with .533/.533 on 1.6rrs
or GTP-3 226/226 @.05 with .534/.534 on 1.6rrs
Are any of these too much cam for the stock motor, I will be uprgading the valve springs, and associated parts and going with Pro Magnum RRs (1.6, non self aligning, 7/16" studs) guideplates, chromemoly pushrods.
I know a ton of people run the Hotcam and get good power, and I hear very good things about the LPE cam, I am looking for the max supportable street driveable power and trying to find my best option.
Thanks for any help and or opinions
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Too Big A Cam? (Epyon127)
It's not so much lift that makes a cam "too much" as overlap. Excessive lift means you need to consider valve train upgrades.
Look at duration and LSA. For a good street engine look for not much over 225 deg and LSA not under 112 deg.
BTW, do those duration numbers reflect the ~2 deg added by the 1.6:1 RRs?
Look at duration and LSA. For a good street engine look for not much over 225 deg and LSA not under 112 deg.
BTW, do those duration numbers reflect the ~2 deg added by the 1.6:1 RRs?
Thread Starter
Instructor
Joined: Mar 2003
Posts: 176
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From: Holtsville NY
Re: Too Big A Cam? (65Z01)
Three of them are 112 LSA and the Comp Cams 305 is 114
Yes those lifts are all the 1.6 ratio
HOTCAM .492/.492 w/1.5rrs .525/.525 w/1.6rrs .558/.558 w/1.7rrs
219 .525/.525 w/1.5rrs .560/.560 w/1.6rrs .595/.595 w/1.7rrs
305 .510/.510 w/1.5rrs .533/.533 w/1.6rrs .578/.578 w/1.7rrs
GTP-3 .501/.501 w/1.5rrs .534/.534 w/1.6rrs .568/.568 w/1.7rrs
Yes those lifts are all the 1.6 ratio
HOTCAM .492/.492 w/1.5rrs .525/.525 w/1.6rrs .558/.558 w/1.7rrs
219 .525/.525 w/1.5rrs .560/.560 w/1.6rrs .595/.595 w/1.7rrs
305 .510/.510 w/1.5rrs .533/.533 w/1.6rrs .578/.578 w/1.7rrs
GTP-3 .501/.501 w/1.5rrs .534/.534 w/1.6rrs .568/.568 w/1.7rrs
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Too Big A Cam? (Epyon127)
With a LSA of 112 deg or larger I don't think overlap will be excessive with those cams.
Of course you will need double springs or equivallent with those lifts; single springs with dampers are only good to around .520" lift.
Of course you will need double springs or equivallent with those lifts; single springs with dampers are only good to around .520" lift.
Melting Slicks
Joined: Jan 2002
Posts: 3,159
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Re: Too Big A Cam? (Epyon127)
unless its for $ reason, the LT4 hotcam isn;t the best choice. great package and great price, but its definatly not optimized.
Guys on the camrao forum are running the Xe 236/242 on stock bottom end with home ported LT1 heads making close to 400rwhp... go figure.
they dont seem to mind the idle quality, but that is subjective i suppose.
Hes floating valves at his high RPMs. I think a 233/239ish cam woulda been good for him.
Keep in mind that LSA is not a free "make it tame" tool.
I asked this same question a while back. http://web.camaross.com/forums/showt...&highlight=LT4
then I did some reading on my own. Overlap is incredibly important in a NA motor. without it, everything falls apart.i wouldn't go wider than 112 LSA persoanlly unless you had some emissions problem?
Guys on the camrao forum are running the Xe 236/242 on stock bottom end with home ported LT1 heads making close to 400rwhp... go figure.
they dont seem to mind the idle quality, but that is subjective i suppose.
Hes floating valves at his high RPMs. I think a 233/239ish cam woulda been good for him.
Keep in mind that LSA is not a free "make it tame" tool.
I asked this same question a while back. http://web.camaross.com/forums/showt...&highlight=LT4
then I did some reading on my own. Overlap is incredibly important in a NA motor. without it, everything falls apart.i wouldn't go wider than 112 LSA persoanlly unless you had some emissions problem?
Instructor
Joined: Dec 2000
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From: SoCal
Re: Too Big A Cam? (Epyon127)
How high do you want to rev your motor? Are you doing any head work? If you're not porting your heads I would go with a smaller cam so you don't have to rev to 6,500 RPM. Check out the Comp 304, it works great with stock LT1 heads and peaks before 6,000 RPM. It has a nice sounding idle too.
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Melting Slicks
Joined: Jan 2002
Posts: 3,159
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Re: Too Big A Cam? (Epyon127)
http://www.compcams.com/Base/Images/...ration-002.gif
using that diagram you can tell its just IVO -EVC
Im currious though, when they measure overlap, is it total deg above .050 or is it above .009\6
using that diagram you can tell its just IVO -EVC
Im currious though, when they measure overlap, is it total deg above .050 or is it above .009\6
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Too Big A Cam? (Epyon127)
Interesting topic.
Last week I was concerned about the same thing (LSA) so I used Engine Analyzer Pro to run back to back simulations to see just what the difference would be.
I used all the specs of my engine and changed only the LSA , starting at 108 and increasing in 2 degree increments through 114.
The tighter the LSA, the more torque and more peaky the torque and the lower the vacuum. Power difference was single digit, but not across the board.
Higher off idle (which surprised me) about equal up to 3500 then the tighter LSA was higher to 6200 where I had the program set to stop.
Off idle (900 rpms) was on the order of 20 lb/ft of torque, but dropped to single digits at about 1500 or so for the tight LSA runs.
Average numbers though, from 900 to 6200 worked out to only a few HP and lb ft/of torque.
So the question for me was "Is the rougher idle and lower vacuum worth the small power increase of running, say, a 110 LSA?"
Jake
Last week I was concerned about the same thing (LSA) so I used Engine Analyzer Pro to run back to back simulations to see just what the difference would be.
I used all the specs of my engine and changed only the LSA , starting at 108 and increasing in 2 degree increments through 114.
The tighter the LSA, the more torque and more peaky the torque and the lower the vacuum. Power difference was single digit, but not across the board.
Higher off idle (which surprised me) about equal up to 3500 then the tighter LSA was higher to 6200 where I had the program set to stop.
Off idle (900 rpms) was on the order of 20 lb/ft of torque, but dropped to single digits at about 1500 or so for the tight LSA runs.
Average numbers though, from 900 to 6200 worked out to only a few HP and lb ft/of torque.
So the question for me was "Is the rougher idle and lower vacuum worth the small power increase of running, say, a 110 LSA?"
Jake
Pro
Joined: Feb 2002
Posts: 744
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From: Houston Tx
Re: Too Big A Cam? (Epyon127)
Good info here......each of the cams mentioned should make for a pretty good streetable LT1. I agree with what most have said.
I chose the Hot Cam because the gain of a few hp at the top to sacrifice low end and mid range and much more importantly, potential driveability at partial throttle. I had heard and driven Hot Cam cars that drive like stockers (very good throttle response , no surging etc.) with just a little lope at idle and much more power than stockers. I went with 1.7 rr's (and of course the entire valvetrain suitable for them) which essentially add most to lift (taking it to ~.56 from .525 with 1.6's) and gain hp everywhere.
For a drag racer , wide open throttle for the most power may be more important , but for the street, autoXing and open track events , I thought the Hot Cam would work best for now.
Hope that helps. :)
Oh and remember that advertised numbers are nice but real dyno , track and "seat of the pants" tell the actual story. This again is where the Hot Cam is peerless, very proven goods.
[Modified by Shriker, 6:34 PM 12/6/2003]
I chose the Hot Cam because the gain of a few hp at the top to sacrifice low end and mid range and much more importantly, potential driveability at partial throttle. I had heard and driven Hot Cam cars that drive like stockers (very good throttle response , no surging etc.) with just a little lope at idle and much more power than stockers. I went with 1.7 rr's (and of course the entire valvetrain suitable for them) which essentially add most to lift (taking it to ~.56 from .525 with 1.6's) and gain hp everywhere.
For a drag racer , wide open throttle for the most power may be more important , but for the street, autoXing and open track events , I thought the Hot Cam would work best for now.
Hope that helps. :)
Oh and remember that advertised numbers are nice but real dyno , track and "seat of the pants" tell the actual story. This again is where the Hot Cam is peerless, very proven goods.
[Modified by Shriker, 6:34 PM 12/6/2003]
Le Mans Master
Joined: Oct 1999
Posts: 9,713
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From: Sachse Texas
Cruise-In I Veteran
Cruise-In II Veteran
Re: Too Big A Cam? (Shriker)
Any of those cams will work fine on a stock bottom end motor. Probably better if it is a 6-speed over an automatic. If it is an auto, then it would work better with a higher stall convertor.
I personally think the CC305 cam is a great choice for a stock bottom end car. I ran one in my 396 a long time ago and it made that stroker pretty small, but with 350 cubes I think it would be a blast and not rev to the sky. Too many RPMs on a stock bottom end will just prematurely kill those stock crank bearings causing a full rebuild.
I personally think the CC305 cam is a great choice for a stock bottom end car. I ran one in my 396 a long time ago and it made that stroker pretty small, but with 350 cubes I think it would be a blast and not rev to the sky. Too many RPMs on a stock bottom end will just prematurely kill those stock crank bearings causing a full rebuild.
