446ci with LS7 Heads
Thread Starter
TECH Addict
iTrader: (24)
Joined: May 2005
Posts: 2,045
Likes: 4
From: Fort Worth, TX
446ci with LS7 Heads Hello Everyone!
I'm having a 446 ci LS2 Darton Sleeved at a 4.16bore/4.1stroke built over at MizFit Motorsports! I've got to say, that Taylor over there is ONE HELL OF A GUY. I've also been working with SLED28, and he is a real stand up guy as well! I would highly recommend going to these guys for any of your build requirements!!
Now, all introductions aside, I'm now working on setting up a cam for this build. We have been throwing around some ideas, but I want to know what everyone here thinks! I did a post early, and all I got was go to EDC, or call up Katech, but thats not really gratifying to me, so please don't suggest that I go somewhere to buy an off the shelf stick.
We've been throwing around the idea, that for such a big ci motor to have something along the lines of 260's for duration and since I'll be using Patriot Gold Springs have lift in the area of .640int/.620exh.
I've been reading a lot about IV/EV events, and maximizing DCR ect... Were going to be running 11.5:1 compression on pumpgas.
What does a cam on XER lobes 262/268 .642/.612 on a 114+2
What sort of differences would I see with a smaller cam on LSK lobes. What are some other lobes that you guys might recommend I use to maximize the lift and duration events of the valves for the LS7 head flow characteristics? We would obviously want a lobe profile which will maximize duration above .350 lift because thats where the LS7 heads REALLY pick up flow.
Just for everyones reference, here is the flow thanks to Richard over at WCCH!
Where shooting for 650 to the wheels on this setup, which I feel will be doable with the ci, and LS7 topend.
Thanks!
Adrian
I'm having a 446 ci LS2 Darton Sleeved at a 4.16bore/4.1stroke built over at MizFit Motorsports! I've got to say, that Taylor over there is ONE HELL OF A GUY. I've also been working with SLED28, and he is a real stand up guy as well! I would highly recommend going to these guys for any of your build requirements!!
Now, all introductions aside, I'm now working on setting up a cam for this build. We have been throwing around some ideas, but I want to know what everyone here thinks! I did a post early, and all I got was go to EDC, or call up Katech, but thats not really gratifying to me, so please don't suggest that I go somewhere to buy an off the shelf stick.
We've been throwing around the idea, that for such a big ci motor to have something along the lines of 260's for duration and since I'll be using Patriot Gold Springs have lift in the area of .640int/.620exh.
I've been reading a lot about IV/EV events, and maximizing DCR ect... Were going to be running 11.5:1 compression on pumpgas.
What does a cam on XER lobes 262/268 .642/.612 on a 114+2
What sort of differences would I see with a smaller cam on LSK lobes. What are some other lobes that you guys might recommend I use to maximize the lift and duration events of the valves for the LS7 head flow characteristics? We would obviously want a lobe profile which will maximize duration above .350 lift because thats where the LS7 heads REALLY pick up flow.
Just for everyones reference, here is the flow thanks to Richard over at WCCH!
I recently flow tested a new pair of LS7 heads and intake manifold. I realize LS7 head flow data has been previously posted but I thought I’d add a bit more data to the mix. The heads were casting #8452. The test valves are oem. Apparently the titanium intake valves are on hiatus for a while, but I managed to scare up a couple for testing and mockup. The intake head flow is as follows:
Lift __.100 _.200 _.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650 _.700
#1 Int. 75.5 162.7 245.5 279.1 305.8 326.4 344.5 360.2 370.7 333.7 336.1
#2 Int. 75.3 163.5 244.0 277.0 303.8 323.7 342.2 359.4 370.6 332.3 335.9
The heads were tested on a SF 600 flow bench.
The intake ports were tested with a radius flow plate on a 4.155” test bore.
I then tested the same ports with an LS7 intake manifold bolted in place:
#5 Int. 74.9 157.7 228.2 254.8 276.9 293.9 306.5 317.4 325.4 331.4 302.2
#7 Int. 75.0 158.3 227.6 254.5 276.0 293.7 306.5 316.9 326.0 331.4 304.8
Due to word wrapping I trimmed a couple of lift points off below .300" and above .700".
As you can see the intake manifold extended the flow peak by .050”, though it reduced peak flow by 45cfm. The flow peak is within the designed lift curve. This is very impressive flow under the peak. Great job designing and machine finishing the ports, chambers and seats.
On the exhaust side, the exhaust ports flow is as follows:
Lift ___.100 _.200 _.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650 _.700
#1 Exh. 57.5 118.8 176.7 207.3 221.7 229.7 235.9 240.8 243.9 246.2 247.9
#2 Exh. 26.2 115.4 168.5 194.4 206.2 213.4 218.5 222.9 225.6 227.8 228.9
The #1 exhaust port was tested with a 1.875” dia. Pipe 2.5” long.
The #2 exhaust port was tested with out a test pipe.
The runner volumes are as follows:
#1 intake runner = 259.0cc
#3 intake runner = 259.4cc
#1 exhaust runner volume = 86.4cc
#3 exhaust runner volume = 85.0cc
#1 combustion chamber volume = 70.0cc
#3 combustion chamber volume = 70.4cc
Lift __.100 _.200 _.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650 _.700
#1 Int. 75.5 162.7 245.5 279.1 305.8 326.4 344.5 360.2 370.7 333.7 336.1
#2 Int. 75.3 163.5 244.0 277.0 303.8 323.7 342.2 359.4 370.6 332.3 335.9
The heads were tested on a SF 600 flow bench.
The intake ports were tested with a radius flow plate on a 4.155” test bore.
I then tested the same ports with an LS7 intake manifold bolted in place:
#5 Int. 74.9 157.7 228.2 254.8 276.9 293.9 306.5 317.4 325.4 331.4 302.2
#7 Int. 75.0 158.3 227.6 254.5 276.0 293.7 306.5 316.9 326.0 331.4 304.8
Due to word wrapping I trimmed a couple of lift points off below .300" and above .700".
As you can see the intake manifold extended the flow peak by .050”, though it reduced peak flow by 45cfm. The flow peak is within the designed lift curve. This is very impressive flow under the peak. Great job designing and machine finishing the ports, chambers and seats.
On the exhaust side, the exhaust ports flow is as follows:
Lift ___.100 _.200 _.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650 _.700
#1 Exh. 57.5 118.8 176.7 207.3 221.7 229.7 235.9 240.8 243.9 246.2 247.9
#2 Exh. 26.2 115.4 168.5 194.4 206.2 213.4 218.5 222.9 225.6 227.8 228.9
The #1 exhaust port was tested with a 1.875” dia. Pipe 2.5” long.
The #2 exhaust port was tested with out a test pipe.
The runner volumes are as follows:
#1 intake runner = 259.0cc
#3 intake runner = 259.4cc
#1 exhaust runner volume = 86.4cc
#3 exhaust runner volume = 85.0cc
#1 combustion chamber volume = 70.0cc
#3 combustion chamber volume = 70.4cc
Thanks!
Adrian
Originally Posted by Haans249
Hello Everyone!
I'm having a 446 ci LS2 Darton Sleeved at a 4.16bore/4.1stroke built over at MizFit Motorsports! I've got to say, that Taylor over there is ONE HELL OF A GUY. I've also been working with SLED28, and he is a real stand up guy as well! I would highly recommend going to these guys for any of your build requirements!!
Now, all introductions aside, I'm now working on setting up a cam for this build. We have been throwing around some ideas, but I want to know what everyone here thinks! I did a post early, and all I got was go to EDC, or call up Katech, but thats not really gratifying to me, so please don't suggest that I go somewhere to buy an off the shelf stick.
We've been throwing around the idea, that for such a big ci motor to have something along the lines of 260's for duration and since I'll be using Patriot Gold Springs have lift in the area of .640int/.620exh.
I've been reading a lot about IV/EV events, and maximizing DCR ect... Were going to be running 11.5:1 compression on pumpgas.
What does a cam on XER lobes 262/268 .642/.612 on a 114+2
What sort of differences would I see with a smaller cam on LSK lobes. What are some other lobes that you guys might recommend I use to maximize the lift and duration events of the valves for the LS7 head flow characteristics? We would obviously want a lobe profile which will maximize duration above .350 lift because thats where the LS7 heads REALLY pick up flow.
Just for everyones reference, here is the flow thanks to Richard over at WCCH!
Where shooting for 650 to the wheels on this setup, which I feel will be doable with the ci, and LS7 topend.
Thanks!
Adrian
I'm having a 446 ci LS2 Darton Sleeved at a 4.16bore/4.1stroke built over at MizFit Motorsports! I've got to say, that Taylor over there is ONE HELL OF A GUY. I've also been working with SLED28, and he is a real stand up guy as well! I would highly recommend going to these guys for any of your build requirements!!
Now, all introductions aside, I'm now working on setting up a cam for this build. We have been throwing around some ideas, but I want to know what everyone here thinks! I did a post early, and all I got was go to EDC, or call up Katech, but thats not really gratifying to me, so please don't suggest that I go somewhere to buy an off the shelf stick.
We've been throwing around the idea, that for such a big ci motor to have something along the lines of 260's for duration and since I'll be using Patriot Gold Springs have lift in the area of .640int/.620exh.
I've been reading a lot about IV/EV events, and maximizing DCR ect... Were going to be running 11.5:1 compression on pumpgas.
What does a cam on XER lobes 262/268 .642/.612 on a 114+2
What sort of differences would I see with a smaller cam on LSK lobes. What are some other lobes that you guys might recommend I use to maximize the lift and duration events of the valves for the LS7 head flow characteristics? We would obviously want a lobe profile which will maximize duration above .350 lift because thats where the LS7 heads REALLY pick up flow.
Just for everyones reference, here is the flow thanks to Richard over at WCCH!
Where shooting for 650 to the wheels on this setup, which I feel will be doable with the ci, and LS7 topend.
Thanks!
Adrian
Stock LS7 intake @ .600: 362 cfm
Katech LS7 intake @ .600: 366 cfm
Stock LS7 intake @ .750: 330 cfm
Katech LS7 intake @ .750: 383 cfm
We use PSI springs and Katech titanium retainers.
We found no gains across the board from porting the exhaust. Any small gains we made on the bottom end changed the top end and vice-versa.
Why such a huge cam? Obviouslly your wanting to go hydraullic, but if your looking for a cam of that size, you may want to look into a solid to maximize the DCR aspect your looking at. A cam in the 260's is going to give a lower DCR, and probally not be controlable with Patriot springs. FWIW, XE-R cams stop at 248*. Yu would have to go to LSK's or a diffrent style lobe to get bigger. I've been through this alot with people concerning my application. When picking up a good flowing intake/head combo, like your doing, A huge camshaft isn't needed. You've got to think, your an automatic 30cfm better than the best FAST 90/90 combo out there. They have to pick bigger cams to make up for a lack of intake, you don't. It's all about efficency. Your also picking up intake flow, but still keeping a exaust flow of a normal LS-1 ported head. This would lead me to believe you going to want to drag out the duration split to help with evacuating the exaust side. Wit my Harrop/ET265 combo, I plan to run something in the 24x/25x range on LSK lobes. My goal, 650+, which should be easily obtainable considering I should have no intake loss to the heads.
Thread Starter
TECH Addict
iTrader: (24)
Joined: May 2005
Posts: 2,045
Likes: 4
From: Fort Worth, TX
What sort of valve events are you looking at with the LSK lobes on a 24X/25X range? I didn't know about the XER stopping at 248*, so I guess I will have to look elsewhere. I wasn't really sure how big is too big, because I've never delt with this size of a motor. But you're right, we definitely don't want to OVER cam. Also, the only thing with increasing the split, is the amount of overlap. With your Harrop intake, overlap isn't a problem, because there is not one main plenum to contaminate with exhaust gases like the regular LSX type manifolds, so driveability will go out the window. But of course, LSA and ICL play a major role in the amount of overlap in the cam. Hell, the stock LS7 cam is advanced about 4 degrees anyways.
I remember reading somewhere about the LSK lobes, and the amount of lift area on the lobe compared to the others. Does anyone have any more info on this? I think the best cam for this project would be lobes that have the greatest duration at and above .350 lift on the intake and exhaust sides. But the more I do think about it, the more that that a 24X/25X makes sense. There is probably good reason why GM designed the LS7 cam with a 20 degree split at .050 between the intake and exhuast sides.
I remember reading somewhere about the LSK lobes, and the amount of lift area on the lobe compared to the others. Does anyone have any more info on this? I think the best cam for this project would be lobes that have the greatest duration at and above .350 lift on the intake and exhaust sides. But the more I do think about it, the more that that a 24X/25X makes sense. There is probably good reason why GM designed the LS7 cam with a 20 degree split at .050 between the intake and exhuast sides.
This is something I am looking at for my next set-up. LS7 heads and intake. A 441 or something along those lines. I would like to be in the mid to high 500s with a smaller cam for drivabilty though.
good luck
good luck
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo LSA has more of an effect on overlap than duration split. However, if you open up the exaust, you should be able to stay around 10* or so of split. Nothing drastic, like the 20* on the stock LS7 cam. It comes to a point when your gunna have to make a sacrifice. With the heads/intake, you need the split, but don't want all the overlap. So what do you do? Funny that Kumair brought Futral into the equation, I was thinking about a cam he spec'd out for me when I was building a diffrent motor. it was a 251/257. I would think the 251 intake coupled with Kumairs 261 exaust would make for a good choice.
Thread Starter
TECH Addict
iTrader: (24)
Joined: May 2005
Posts: 2,045
Likes: 4
From: Fort Worth, TX
Does anyone know the max lift that the stock rockers can handle before geometry becomes a problem? I'm debating spec'ing out a high lift cam, somewhere in the .71-.72X range.
Katech, how did you work your heads to get that kind of flow in the higher lift? Which PSI springs did you use?
Katech, how did you work your heads to get that kind of flow in the higher lift? Which PSI springs did you use?
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Don't take this the wrong way. But if you posted and it was suggested you might consult with a professional cam grinder on your choice of a custom cam for a custom application then perhaps you should have taken it.
If you are spending all this time and money wouldn't it stand to reason that the heart and soul of your motor might be the one thing you don't "cheap out" on.
As stated, here are some folks to consider speaking with. These are not shelf cam, but rather application specific grinds.
LSM
FTI
Elgin
Katech
I could go on, but you get the idea...
Is ther some reason you don't want to pay for a custom cam? I mean, anyone on here can recommend anything to you. There is no way to know if what they recommend has any merit, or is anywhere close to optimal for your combination.
If you are spening the money on custom 447 with LS7 heads, to me it would be important to have a solid valvetrain.
If you are spending all this time and money wouldn't it stand to reason that the heart and soul of your motor might be the one thing you don't "cheap out" on.
As stated, here are some folks to consider speaking with. These are not shelf cam, but rather application specific grinds.
LSM
FTI
Elgin
Katech
I could go on, but you get the idea...
Is ther some reason you don't want to pay for a custom cam? I mean, anyone on here can recommend anything to you. There is no way to know if what they recommend has any merit, or is anywhere close to optimal for your combination.
If you are spening the money on custom 447 with LS7 heads, to me it would be important to have a solid valvetrain.
Thread Starter
TECH Addict
iTrader: (24)
Joined: May 2005
Posts: 2,045
Likes: 4
From: Fort Worth, TX
I agree completely with you J-rod, and I take no offense what so ever with what you said, so don't worry about that, but this is all a learning experience for me. Yea, I could spend the extra 100 bucks or so and get a custom grind from someone, not a big deal, but that doesn't leave me with anymore knowledge then I had before. I'm in this whole thing because I love learning about these engines, and the science behind it, so I'm very interested in learning on something that is specific to my own build and I know there are guys here that are VERY knowlegable in this area, and I would love to hear their imput.
Thanks!
Adrian
Thanks!
Adrian
Thread Starter
TECH Addict
iTrader: (24)
Joined: May 2005
Posts: 2,045
Likes: 4
From: Fort Worth, TX
Well, I didn't know you have to go solid with lift that high, so I suppose I can forget about that for the time being (may go solid in the future). One of the reasons why I was thinking this, is I remember DAPSUPRSLO (sp?) mentioning that it is beneficial to go above the lift where max flow occurs in the heads, and this makes sense to me. If you only have max lift at that point, then the valve will only be at that lift point once, BUT, if you lift beyond that, then you will hit that lift point twice, meaning more "area" under the curve flow wise, or time at that lift point, hence more inflowing air. I can see huge numbers coming from a setup like that.
But, luck has it, I just got a hold of a set of fully assembled LS7 heads, so the build is coming up close!
Adrian
But, luck has it, I just got a hold of a set of fully assembled LS7 heads, so the build is coming up close!
Adrian
If you ever decide on a grind Comp Cams will grind you one for the same price that you can buy one of their off the shelf grinds. I had one done about 6 weeks ago and bought it through Thunder Racing. You might want to talk to Geoff at TR and get some expert input on a camshaft grind for your application...one thing good about TR after they get the cam back from Comp they put the cam doctor on it for you and provide you with a spec sheet on all of the valve events of the cam.
