Summitracing

Nice work Wes302!

jester1

iTrader: (1)

Well hopefully he actually pushes them on the dyno as he never pushes anything near max. Damn you have the s475 push the damn thing to max inquiring minds want to know.
Yes im nagging and calling you out RH push the damn thing. or r u skerd.

dmaxs10

iTrader: (1)

Looking at 2 of these cams the 8706 and 8716. When do you recommend the 8716 over the 8706? I'm wondering if the 8716 might spool a turbo a little quicker if you have a larger turbine with the change in EVO.

68roadrunner

take a look at his videos. he has pushed a 4.8 and 6.0 to MAX. (big bang motors) haha.

2JZFC

iTrader: (26)

Anyone using the stage 4 turbo cam or have a link to any tests, comparisons, etc?

Broke a valve spring and it snowballed from there. Lifter hammered the cam lobe, rocker bolt loosened up, rocker mushroomed the valve tip and with the exhaust valve only partially opening, it lifted the head.

Since I have to replace the BTR stage 4, and since I'm pinching pennies, I was wondering how the Summit stage 4 compared and what difference I might see with a 402ci. My own damn fault as I have been hammering on this poor engine and other than the occasional leak-down, haven't even taken off the valve covers in 3+ yrs. Man, you would think an LS could handle more abuse than that

SLOW SEDAN

iTrader: (13)

I posted results of the stage 4 earlier but it was compared to the btr stage 3 on a 5.3L.

stacy moore

how would the stage 1 or 2 work with a 4.8 or 5.3 with twins?

Summitracing

2JZFC, can you give us a little more information on your combination? For now, we can give you some basics based on valve events. The Pro LS SUM-8717 stage 4 turbo cam has a comparable intake opening to the BTR stage 4 turbo so it would share similar idle characteristics. We close the intake valve three degrees later so the powerband will be moved up in the range from the BTR. Exhaust opening event is near identical so turbo spool-up should be similar. Where things differ is the Exhaust closing event. BTR stage 4 closes at 0.5* BTDC. Our stage 4 turbo cam closes the exhaust at 5* BTDC. Closing the exhaust valve earlier helps keep turbine backpressure in check and prevent backflow of exhaust gasses back into the intake. This is especially happy with single turbo applications or even twins running a full exhaust.

Our stage 4 also has 4.5* less overlap at 2*. Not that a stage 4 cam is typically something where we're looking for good driveability, but ours would be better here in that aspect.

Summitracing

In general, they would work well in a twin-turbo application. More info about your combo and goals would be helpful to provide a recommendation. With a 4.8, there’s a chance our Stage 2 truck cam SUM-8720 would a good candidate. Specs on it are .600/.600, 218/227, 112 + 2. There's a humorous but descriptive review on this cam in a turbo 4.8 application. Check out "the sauce" review on our site.

Summitracing

We replied to your post about this over on the "check out the NEWEST Summit Pro LS cams" thread. You provided more info on that post so we replied there.

2JZFC

iTrader: (26)

Slow Sedan and Summit, thanks for the replies.

It is a Summit gen IV 6.0L bare block with a Manley 402 rotating assembly, 18cc dish (#28402R), ARP main and head studs. Stock 5364 heads (9.5:1 c.r.), upgraded springs, upgraded rockers, Lunati short-travel link-bar lifters, China Sniper intake, 102mm TB, 210lb Bosch (pump E85), flipped truck manifolds, 2.5" x-over, Billet S485/102mm turbine, 5" into 4" DP/fender exit, 5" A2A, PTC 10" converter, TH400, 3.08:1, 275DRs.

Car is '92 Fox notch weighing 3300# w/driver. It is primarily a drag car but driven not towed with the occasional gearhead gatherings. Can't say there's anything wrong with the BTR stage 4 as I've never tried anything else. It fires right up, idles fine and drivability is as expected. However, since I have to replace it, if there is something better or equivalent but less expensive, it's certainly a consideration. One thing I have never understood is when looking at cam selections, you see cams specific for LS3 N/A, LS3 supercharged but not LS3 turbo. Does turbocharging negate the difference of LS3-headed engines?

Kfxguy

iTrader: (1)

Holdener just posted a video to YouTube showing you don’t need a special cam for a turbo motor.

2JZFC

iTrader: (26)

Interesting video.

stacy moore

That's a funny read for sure.... LOL
so at 4300# with the SUM-8720 cam w/ TFS-16918 style beehive springs what stall converter for max effort with bw366 turbos?

Summitracing

We do a lot of work with Richard, but a lot of damage can occur if the cam has too much overlap and the turbo has a lot of restriction at the turbine. You’ll see that our intake valve events are the same on our N/A and turbo cams but we close the exhaust in direct relation of intake opening to limit overlap

Summitracing

With our Ls3 specific cams, we dial back exhaust closing a tad to prevent reversion into a relatively lazy intake port (big valve and CSA). We also offset the lobes a bit to get slightly better piston to valve clearance with the big 2.165 valve and a True flat top.

Your car is well thought out. We think our stage 3 turbo cam will be as quick or quicker with that 308 gear and that short runner intake.

Kfxguy

iTrader: (1)

well I mentioned to him the overlap, how fast it spools and the fact that we don’t race Dyno’s. Performance on the Dyno doesn’t tell the tale on the street or track.

Summitracing

This will take more info. We find it best in these situations to work through PM. We sent you a PM to help you with selecting a converter for your application.

jester1

iTrader: (1)

Hey Summit out of curiosity 8706 what diameter base circle is this cut on. I forgot to measure before installation. Thanks.

Summitracing

No problem. With .600/.575 lift and the lobe's noses being .010 under the 55mm cam journal, the base circle radius is .719 Int. and.734 Exh. and diameter becomes 1.438I/1.468E