gnx7

iTrader: (28)

So here are 3 cam choices I have on the shelf at my shop and would like some input:

Motor is a 364ci LS2 boost motor with approx 9.5:1 compression, TFS 225 heads, LS6 intake, with a Comp Turbo CT80 turbo rated at 123lbs/min 1150hp. I want to spin it to 7200 or so at times and prefer to make decent power lower in the RPM range; however I do want it to be strong from 45000-7K RPM. I will be running it about 99% of the time on e85 and it has a GForce built T56 with billet gears/shafts into a 8.8" IRS Cobra diff/DriveShaft Shop race axles. This combo is going in a FD RX-7 with a target weight of 2600lbs wet so low end power isn't as much of a concern as a 3500lb car. I have a 335/30/18 out back currently with room for more tire if needed.

I have 3 diff choices built up:
#1 runs a 3.31 gear/DPI Platinum road race LSD
#2 a 3.08 gear/stock Cobra Track-Lok
#3 a 2.73 gear/Moser spool.

Goals are to go road racing most of the time and 1-2x per year do 1 mile shootout events. 3.31 gear for the road courses and 700-800rwhp setting and then either the 3.08 or 2.73 gear for the 1 mile shootout stuff and/or drag racing with 1000rwhp or whatever the turbo maxes out at. This won't be professionally raced. More of a wild track car.

Cam choices:

Patriot Performance 225/229 .580"/.590" 114+4 LSA
or
Comp Cams 225/223 .571"/.564" 114+3 LSA
XER reverse split GRIND (reverse the intake/exhaust in this link)
http://www.ls2.com/forums/archive/in.../t-203567.html
and finally
Virgina Speed v3 turbo cam reverse split low/mid 230 duration cam with lift around .600"

***I assume the VS cam will move the power band more to the upper RPMs and the smaller mid 22x duration cams will run out of breath after 6000 or so?

Attached is the compressor map for my turbo. 1.15 A/R T4 turbine with 4" outlet.

Suggestions on cam choice or maybe top 2? Plus why?

TurboAv

iTrader: (6)

The single T4 is going to run in to backpressure issues wanting 7200rpm out of that combo. You will have to cam around that and/or run less rpm. I would honestly contact Virginia Speed and talk with them.

kmracer

iTrader: (1)

i suggest you read some books and articles by david vizard. i remember looking forward to his articles almost every month in PHR. very very technical and in depth, yet easy to understand. he's got articles covering everything to do with an engine, air filter to muffler...

JAX04

iTrader: (17)

Thanks man, ill do that for sure, Im a knowledge hungry kind of person, so anything i can learn, im all for it!

Patrick G

iTrader: (14)

Mark, I've seen the specs of the VS cam and it looks to be the best choice of your 3, especially with a light vehicle and a 7200 rpm powerband choice. It will be a little laggy compared to the reverse/split Comp, but it will be the only one of the 3 that will pull hard to 7k IMO.

gnx7

iTrader: (28)

to the top!

VUSS383

Subscribe !!

ausls1

Wow was looking to see what cam specs people were running for FI 383 ls1's in particular twin turbos and got stuck reading all 6 pages, good read, gives me some more insight and ideas of what i want to run with comp ratio, cam specs, etc. I think a custom cam might be on the agenda now.

ausls1

Could you get away with a cam like the magic stick 3 or 4 and a centrifugal s/c on a 112 lsa in a ls1383 stroker motor with a comp ratio around 10.3-10.5? Just curious. Or a set of twin turbos. With a 98ron or e85 pump fuel?

ausls1

Just curious as will have a compratio in the low 11's cr but can drop it to the 10.3/5 with factory or 0.060" thickness head gaskets.

gallo-lo

iTrader: (11)

im building an stock lq4 for a t6 88mm with a 1.32ar, im going to go with blowthru e85 and powerglide this is going to my 275drag radial outlaw Vega, car weighs 2400lbs. im loooking into this cam276/268 115lsa with .650/.650 lift

Sarg

iTrader: (6)

Having talked to a couple different shops about twins on a 5.3 I am still getting the reverse split cam recommendation from most people. I did get one recommendation from a shop for a mild 228/232 cam though. I have still not made up my mind at this point, but reading through this has given me a bit more to think about.

quik67

QUOTE=Sarg;15462301]Having talked to a couple different shops about twins on a 5.3 I am still getting the reverse split cam recommendation from most people. I did get one recommendation from a shop for a mild 228/232 cam though. I have still not made up my mind at this point, but reading through this has given me a bit more to think about.[/QUOTE]

For what its worth, I have tried 4 different cams in my twin turbo 5.3 . 3 of them were boost grinds 1 is a big N/A cam. Out of all of them the large N/A cam has worked the best for all out power. It pulls extremely hard above 4500 rpm with 15 psi boost! It did suffer down low, but after installing a 4500 rpm converter, it is no longer an issue.
Boost grinds: 216/216 .550.550 115 lsa
220/224 .575/.575 114 lsa
218/227 .607/.610 113 lsa
N/A grind: 237/242 .603/.607 113 lsa

tripblackls1

iTrader: (11)

That n/a cam looks like a ms3?

quik67

yes sir, it is.

Sarg

iTrader: (6)

See the only one of those that I would associate with a traditional boost cam is the first one. I am coming from the import world where I am used to seeing 272/272 total duration or like my last cam, 282/278. Not sure what they are at 50 as they are rated in mm.

I think the main thing is matching the cam to your power band for the examples above. If you have turbos that do not spool till 4500 and a cam that is starting to run out at 5500 rpms then it would be a bit of a mismatch. But that is just a guess.

I know the 2.5 liter Subaru motor that made around 550 awhp still had a fairly mild 272/272 cam and pulled all the way to redline. That motor probably was putting out over 675 at the crank.

ausls1

Quik67 you have bassicaly answered my question as I'm looking at for my 383 ls1 a 244/248 112lsa ot the ms3 or ms4 grind and a cam in Australia that is virtually identical to the ms3, just a .002 extra in lift I think, the cimpany that does it call it a turbo killer
cam, will be in a 112lsa but a 113 might be better if I add a blower later on unless won't make much difference with that small an lsa change.

ausls1

Will only run 8-10 psi at the most anyway, maybe 12-15 at the absolute very most, but some time down the track.

quik67

I would give it a try. I was told many,many times the MS3 was way too big for
turbos and my little 5.3, but I can't argue with the results. I don't have dyno numbers or track times yet, but i do have a lot of street miles on it and know it works really well for my combination. I am using cheap ebay gt35 turbos .82 ar.They reach full spool right at 4500 rpm. I am going to put the stock heads back on with a little port work and raise the compression back to 9.5:01, I have 317 heads on it now.

VUSS383

Ausls1 , i'll give you a few tips of where im at with playing with turbo's here in aus .
First example is a stock VU SS : De-comped to 9.7, 1.8 roller rockers & ARP rod bolts . Other then this it is 100% stock . Turbo's are an unknown as they are twin chinese T3's with a stupidly small front cover but large rear ( 1 day ill measure the wheels ) on stock cast manifolds with steam pipe " J " Pipes to the turbo's. This engine has been boosted for 6+ yrs & currently runs 18 psi of boost on BP Ult 98 . Results on lower boost 646 HP on a dyna pack hub dyno .


2nd example is same turbo's running on forged 383 LS1 .... 11.1 CR , 242/238 .609/.605 0n 116 , 18.5 psi , in another VU SS would light tyres at 160 - 180 kph with 3.46 diff in 4th & 5th with simple throttle application ( no dyno figures on this 1 which is a shame ) but drove great on the street out of boost . Boost delivery was simply like being hit by a sledge hammer , if my memory serves me correctly full boost was before 3000 rpm & they started spooling at around 2600 - 2700 ( i'd have to look back through my logs).Also run on 98 . Engine died @ over 20psi during R&D ( lifted head / unhappy bore ).

This shows high comp & turbo's can live in harmony !!

Just more to think about .