Turbo cam help!
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From: Harford co. MD
Turbo cam help! I am in the process of having a LSX 427 shortblock built which will consist of 9.5:1 comp. ported PRC 285cc heads,probably a victor jr or proflo intake ,big single or twin setup, 4l80e with conv. to match the combo street/strip i would like something with a choppy idle but decent low end. Here is what was recommended to me=
223/232@.050 .578 .587 115lsa
It is a turbo cam so the wide lsa will make for a smoother idle and will keep from bleeding off boost. It will have great drive ability and will be gentle on valvetrain. It will work great to build boost at a low level 2000rpm (will depend on turbo could be sooner or later). The top end will depend on the boost settings on the turbos.
Is this the best route or ??? I do want to hear it and understand i may lose some bottom end to get it any help/recommendations would greatly be appreciated!
223/232@.050 .578 .587 115lsa
It is a turbo cam so the wide lsa will make for a smoother idle and will keep from bleeding off boost. It will have great drive ability and will be gentle on valvetrain. It will work great to build boost at a low level 2000rpm (will depend on turbo could be sooner or later). The top end will depend on the boost settings on the turbos.
Is this the best route or ??? I do want to hear it and understand i may lose some bottom end to get it any help/recommendations would greatly be appreciated!
I just got back from a new tuner I'm gonna go with, but anyways they have a lsx 427 and it has about the same cam duration as you mentioned. But he is running e85 and getting 1300hp out of it. They race 1/8 mile with it, sounds like a normal LSx sitting there idealing. They were doing a tune on it for this weekend so I got to hear it.
That is a pretty small cam for a 427.
Not what I would use.
I can see what they were doing with the valve events and they have the right idea, the events just need to be later as it's a fairly good sized motor. Now if you don't want to turn it over 6300rpm and have it peak at 6500 then use that cam.
Depending on the turbo you use and intake will determine what cam you need since you already have your chosen stroke, cylinder head, and compression.
What rear gear, what's the vehicle weight and how high do you want to spin this motor?
Not what I would use.
I can see what they were doing with the valve events and they have the right idea, the events just need to be later as it's a fairly good sized motor. Now if you don't want to turn it over 6300rpm and have it peak at 6500 then use that cam.
Depending on the turbo you use and intake will determine what cam you need since you already have your chosen stroke, cylinder head, and compression.
What rear gear, what's the vehicle weight and how high do you want to spin this motor?
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I thought it was a bit small for the CI but i know Turbo's like a little smaller of a cam then a NA motor. Rear gear will probably be 3.50-3.70 range being it will see some highway and Rpm wise probably in the 68-7000 range as long as it dont kill the low end.
Turbo will probably be twin 78's or a single 91/94mm undecided which route to go yet it seems like the big single puts down easier numbers from what i read.
Turbo will probably be twin 78's or a single 91/94mm undecided which route to go yet it seems like the big single puts down easier numbers from what i read.
I can see your point on the cam thing. But with boosted motors, like you said also they use smaller cams. However you want a min of 10 degrees more on the exhaust side with 114+ ls to make use of the boost. Now granted your a 427 ci LSx I have 383 LT1
but I was on the right track with PT6262 but he mentioned that a 6466 will be better. They spool just as fast and better midrange and positive side of it is better fuel mileage. Maybe you seen my post on asking some same questions. Not meaning to jack your thread. But isnt 78 huge. Or I should ask what power are you going for?
but I was on the right track with PT6262 but he mentioned that a 6466 will be better. They spool just as fast and better midrange and positive side of it is better fuel mileage. Maybe you seen my post on asking some same questions. Not meaning to jack your thread. But isnt 78 huge. Or I should ask what power are you going for?
I asked him on cams also......I'm like holy crap the cams people use on boosted motors are big. And I'm sitting on a 224/230. But back when I built this motor that was a pretty wild cam of the time. And he told me that alot of people are going with to big of cam for what is needed. And then he started telling me about the shop toys and the power he is making with them. And he isnt running huge cams with them either and he is at 1300hp with e85 and not pushing the tune to be on the safe side. So I guess he has some truth to it by doing it and having repeated results to more than one car.
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Yea the 78's may be a little big but seen a few guys running them on smaller CI motors I had originally planned on running a single 4788 and was told many times way to small it will choke out at 5K! But 1300hp at the motor is about where i want to be.
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How much boost do you think you will need to make 1300 hp at the fly wheel? If you are thinking close to 20psi then you may want to look into billet wheel 67mm. If you think you can do that at only 15 then 67's would be a little to small. This is referring to doing it efficiently. At 650hp each and 20 psi they would be nice and efficient. At only 15 psi they would flow the air but they wouldnt be compressing it efficiently.
People always seem to get a bit confused when I try to explain it but, its pretty damn simple. When a turbo spins faster it wants to flow more air (HP) and build more boost. You dont pick a turbo based on "its good for 650hp", you pick one because for example: "its efficient at 650hp at 20psi of boost"
Here is an example:
A Garrett GT4202R (75mm dual ball bearing) says:
Horsepower : 450 - 1000
Displacement : 2.00L - 7.00L
So according to HP and engine size you could say that turbo is good for anything from a 2.0L to a 7.0L as long as its within 450 to 1000hp and that it would be a properly sized turbo. Once you start looking into boost levels you need for that hp and intended usage you start scratching off motors that are still in the 2 to 7 liter and 450 to 1000hp.
BTW I have a brand new GT4202R I am thinking of selling. A mate to it goes for around $2400 online. They would be running at almost peak efficiency at 650hp each and 20psi. You would have a few hundred hp of head room left over to.. as long as youre upping the boost a bit to.
People always seem to get a bit confused when I try to explain it but, its pretty damn simple. When a turbo spins faster it wants to flow more air (HP) and build more boost. You dont pick a turbo based on "its good for 650hp", you pick one because for example: "its efficient at 650hp at 20psi of boost"
Here is an example:
A Garrett GT4202R (75mm dual ball bearing) says:
Horsepower : 450 - 1000
Displacement : 2.00L - 7.00L
So according to HP and engine size you could say that turbo is good for anything from a 2.0L to a 7.0L as long as its within 450 to 1000hp and that it would be a properly sized turbo. Once you start looking into boost levels you need for that hp and intended usage you start scratching off motors that are still in the 2 to 7 liter and 450 to 1000hp.
BTW I have a brand new GT4202R I am thinking of selling. A mate to it goes for around $2400 online. They would be running at almost peak efficiency at 650hp each and 20psi. You would have a few hundred hp of head room left over to.. as long as youre upping the boost a bit to.
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The rear gear will be 3.50-3.70 range as for the stall i was going to base than on the cam but it should be right around 3200 range i would guess. I would probably like to keep the boost around 15psi and have some room to grow if needed so the twin GT4202R's sound like a nice setup that will do just that if i decide on twins. I was also looking at a GT5088 single that Dr Turbo was making refference too! The turbo setup will be down the road a few months when funds are available just trying to get the right cam selected that will work well!
Honestly I wouldn't come on tech and trust some random person to spec me a cam. A 223/232 cam won't lope at all in a 427. My buddy runs a cam around 227/242 and it doesnt lope at all in his LS7. Why not get in touch with someone who specializes in building LSx engines or more specifically turbo LSx engines. Kurt urban performance, ERL and virgina speed would be a good start. You could contact Bullet cams as they are highly recommended or LilJohn or Brian Tooley on yellowbullet would steer you in the right direction.
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I am looking for input from guys that have a similar setup or exp. with cams on this size motor running a turbo. I have a builder who recommended the cam i listed and like you said it will idle smooth which is not what i want i want to hear it! If i get more cam specs they would be listed also so guys here could chime in like yourself to say what or what not that cam will do so it a bit more than letting a random person pick a cam i will not be acting without knowing first.
I have experience with a 228/232 on a 114 in a 427 with twin Precision billet 67's. It idles docile and I wish it had more lope to it but it spools instantly and kicks *** on the street.
Honestly I wouldn't come on tech and trust some random person to spec me a cam. A 223/232 cam won't lope at all in a 427. My buddy runs a cam around 227/242 and it doesnt lope at all in his LS7. Why not get in touch with someone who specializes in building LSx engines or more specifically turbo LSx engines. Kurt urban performance, ERL and virgina speed would be a good start. You could contact Bullet cams as they are highly recommended or LilJohn or Brian Tooley on yellowbullet would steer you in the right direction.
Agreed.
If you want LilJohns number I can give it to you. He used to work at Total Engine Airflow awhile back when Brian Tooley still operated it.
I wouldn't be surprised at all if he specs you something in the 238/242 115+4 or 236/240 115+4 range.
A 223 intake lobe will never pull, well at least not make power to 7000rpm and you'd be way out of the single plane intake manifolds operating range or pro-flo's operating range for peak power. You need at least 12-15* more intake duration to get a 427 to peak at 7000rpm. More like 236-240 intake lobe and 240-242 exhaust lobe with a 115 lsa or 116lsa on a 111-112 installed intake centerline.
Last edited by Fbodyjunkie06; Jun 14, 2012 at 01:07 PM.
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Here are a few more that i got from the builder !
232 236 .625 .625 112lsa
240 248 .625 .625 113lsa
242 242 .625 .625 115LSA the last was said to be the best for 427 and agressive!
232 236 .625 .625 112lsa
240 248 .625 .625 113lsa
242 242 .625 .625 115LSA the last was said to be the best for 427 and agressive!
