I saw on here that someone at one time able to see how a cam would run in a 350 with some software and it got pretty close to what it would do in the actual engine. Just wonder because I what do to see how a scott brown cam will work before I buy and see what it would do with some changes as well. And I was wanting to compare it to the level 4 as well.
Here is some info based on some simulations. Gary will chime in I am sure, he can run the cams in his program for you. I can tell you that scott brown makes amazing custom cams, do not be scared. A friend of mine e-mailed me these calculations and if we can get the heads flowing these numbers it should be possible with my parts. Cam calculations for the heavy duty engine dyno run using the Holset turbocharger: This is a compressor map for a Garrett 88mm turbo similar to your Holset 88mm. If we figure a maximum boost of 25 psi, that is a pressure ratio of 2.75 I have drawn a load line in orange on the graph at a pressure ratio of 2.75 representing where the turbo will operate at 25 lbs of boost. At lower boost levels the load line shifts down and to the left staying within the operating range of the graph. If you look at the bottom of the graph you will see that the engine must pump between 80 and 140 lbs/min of air at that pressure ratio. Our job is to get the engine to pump that much air in order to match the turbo compressor for the turbo to operate correctly. [/URL] We now know that the engine must pump a maximum of 140 lbs/min at 25 lbs of boost. If we limit the engine rpm to 7500, a quick calculation using a hand calculator shows that the engine must have a Volumetric Efficiency close to 100%. Below are the PROJECTED GOAL not actual head flow numbers for the heads as they are still in the R&D phase and will not get to the head porting guy for another few months. Intake .100... 76 .200... 162 .300... 236 .400... 289 .500... 327 .600... 334 Exhaust .100... 56 .200... 124 .300... 179 .400... 210 .500... 238 .600... 250 The 350 roller cam blanks are limited to .380" lobe lift with a LSA range of 108 to 112 at that lift. With a 1.6 rocker you get a .608" max lift. You will need all the lift you can get for a 100% VE. In order to keep the LSA close to 112 degrees using high boost, it requires an exhaust header with long and equal length primary tubes. If we take the above flow numbers 9:1 compression ratio 3.830" bore, 3.85" stroke 1.920" intake valve, 1.550" exhaust valve Valve lift .600", LSA 113 degrees Make the intake and exhaust duration the same. We get the following from the engine simulation software we get 1300 HP and 950 TQ with this 355 inch engine. Notice we have just over 100% VE from 5500 rpm to 7000 rpm. Also notice it took a .050" duration of 245 degrees to do it. [URL=http://smg.photobucket.com/user/seanbuick76/media/untitled%202_zps86osc1c5.png.html][IMG]http://img.photobucket.com/albums/v732/seanbuick76/untitled%202_zps86osc1c5.png Finally if we take the VE numbers from the engine sim software and plug them into the turbocharger calculator you get the following: http://www.turbos.bwauto.com/afterm...wts=400&pt6_wd=83&pt6_wd2=74&pt6_wrsin=92044&
Thats all awesome info! very helpful. I PM'd Gary a couple of days ago and havent heard back from him. I guess the only thing im concerned about with Scott's cam is that the one he said for my 90% street car and that Im going to only spray nitrous a handful of times. the cam he thought would be perfect has .220/.240 duration(seemed like a huge split to me) and .480/.480 lift. And it will be on a 112 lsa. I guess it would kinda ldle/sound and run like a upgraded ta 212 maybe?
Just be patient Gary will do some dyno sims for you.... There is more to a cam than just the specs can show you, I would trust scott. And if you want a muscle car sound just go with a nice big exhaust and magnaflow mufflers, it beats using a cam so big it ruins your low rpm driveability. A huge unknown in your combo is the head flow. If the heads are not professionally ported then stay safe and mild on the camshaft. Here is a 350 that i donated a free camshaft for, and it turned out great. Nick picked a mild lunati cam and it worked perfect for a non ported head 350 to get into the 12s through manifolds in a heavy car. http://www.v8buick.com/showthread.php?224070-Stock-Buick-350-Skylark-runs-12s-in-the-quarter& The cam he used here, less is more in some cases: http://www.v8buick.com/showthread.php?174677-New-Cam-Lunati-33204&highlight=
When you spray Nitrous a lot more exhaust volume is created for a given intake charge volume so the extra exhaust duration helps evacuate the extra exhaust. The simulation should show an extended power band on the upper end especially with nitrous. Scotts cam only has 2 degrees more overlap the a 350 TA 212 cam so the idle will be similar. Paul
Gary is going to need as much engine info as possible to run a simulation. Which header are you using? What is the rest of the exhaust system out to the back? have you decided on an intake manifold? Which Carburetor? Looks like the compression ratio is 9.8:1? Are you going to install larger valves and do port work? Where does the cam's intake lobe center need to be set at? 108 degrees ATDC? Paul
its the hooker 1 3/4 headers 2 1/2 exhaust either stock or the T/A dual plane already have the large valves and will probably do a little work to the bowl I assume its a 108 because most 112 lsa cams are
Compression is around 9.8.1-10.1. Im using .040 head gasket, T/A 10.25 pistons, and I have block 0 decked and the heads shaved .40.
From the FAQs page. http://www.msdperformance.com/AtomicEFI/AtomicFAQ.aspx Injectors are normally rated @ 43.5 psi which would convert these injectors to 68 psi @ 43.5 psi
Your going to have to recheck your measurements. If you used the cast 10 to 1 pistons (10cc dish)at zero deck with .040 off head(estimated 47 cc) your around 12.1 to 1 compression. With that amount off block(around .060) you will need shorter pushrods also. Is you got the 24 cc piston to will be 10.2 but possibly milling .090 off block depending on piston spec.
Oops I put the wrong amount im milling the heads I put the amount im milling a set of sbc heads for a 355 thats going in a Chevelleou:. I have way to many engine projects right now:laugh:. I was only going to take off .010-.020 off the heads. And buy new pushrods as well.
I wouldnt mind being a little over 10.1 compression. Would it still run on 91 at that point? Ive seen sbc and big blocks with 10.5.1 compression run on 91 but Buicks are totally new engine to me.
The compression ratio limit is mainly determined by the camshaft's advertised intake duration. If the compression ratio is over 10:1 the the camshaft advertised intake duration would need to be 280 degrees or more. Don't forget that the Buick 350 head is open chamber and you lose almost 2 cc for every .010" you take off. Paul
How is that? just wondering because I always thought even though its open chamber that you still gain compression. I gained compression on the big block I had that 781 heads(open chamber) by shaving the heads.
It does raise compression. He is just stating the shaving .010 off head is about the equivalent of 2 cc removed from chamber. Depending on head it can be slightly more than 2 cc. Its just an estimate for doing math on compression. I would not go to 10.5 compression with 91 unless your running aluminum heads and still that's pushing it. Run e85 and 12 to 1 .
The atomic efi from MSD. It was given to me. If it were me id switch either to a carb, holley efi, or the fast 2.0 efi.
