L92 Longblock + LSA Supercharger - What Cam?

[DavidBoren]

Yes, the vvt is another system that can fail. But it is still robust enough to be on thousands of warranty covered vehicles. So I don't think that retaining the vvt makes your build any more or less bulletproof than it would be without it.

Plus, you already have it. If the blower accessory drive lines up with the vvt timing cover, then I say see what the stock vvt cam gets you with 12psi of boost.

[mikels]

Originally Posted by RLJ676

Thanks for all the insight everyone.

From what I've been reading the gains w/ a cam and tune even w/ the limiter are still huge, up to 100 hp w/ TSP's cam. Sounds like quite a bit is actually in the tune itself.

Budget is a concern, not to mention part of my fun in this is the challenge of getting the most from the least if that makes sense.

Dave, an LSA motor w/ less compression and simlar boost makes 650 pretty regularly, and that cam I understand to be very mild.

The L92 compression is quite similar to an LS3 (slightly lower actually). I read (on camaro5, etc) of many of them running 12, with quite a few in 13-15 lbs on 93 with no problems. They're making 650+ rear wheel at 12ish pretty easy.

So with the added benefit of VVT, I am now leaning towards actualy the stock cam and 12 lbs of boost, LS7 throttle body and a good tune. I think w/ a cam change I'm going to exceed power goals, as NA that would make 500 ish. Of course I could just do a cam and less boost, but what's the fun in that and it's not efficient $ wise, as then I"m in $800 for cam/springs etc to get the same output.

From what I've been learning on VVT (even w/ the limiter) it makes an awesome torque curve, so adding in the supercharger can only make it better haha. So even if I don't make my goal of 700 crank, which I still think I will, the power under the curve will make it a complete grin machine...well except for the tire costs haha.

Dave I was thinking the GMPP harness kit w/ a tune might be best. I'm going to run the modified CTS-V accessory drive from GM that puts the alternator up high in a vette position for clearance on the bottom. I am trying to determine if the L99 water pump which clears the VVT stuff will work with the CTS V FEAD. Looks like the water pumps due to lack of actual rib/edging are most flexible on belt placement at least.

Reading it seems you are pretty familiar with Thomson, do you know if they can tune for VVT well? If I had the dough I'd just have them be building from scratch for me, especially after seeing the LS7 short block/LS9 screw setups going in at sled alley haha!

Originally Posted by RLJ676

I was also thinking that a thicker head gasket could take a little compression out.

So new head gasket, stock cam, 12 lbs boost and good tune would be the most cost effective formula in my mind. However if for some reason this still wouldn't make good power of course I can just change the cam.

Next up in cost is LS9 cam/springs, head gasket, 12 lbs boost etc, which would probably make more than plenty of power for me, just lose the novelty of VVT/boosted engine. Looks like it's about $450 more (after VVT delete parts).

I'd really like to run 12 lbs due to the Texas Speed balancer pulley, if I need a new pulley I'd like to pay for one that also increases performance vs stock ("free power" if you will since I need a part anyways).

All out then would be a new aggressive VVT cam, limiter, thicker gasket and 12 lbs. I think this would exceed my power goals (limited by $$$ for corresponding upgrades), and be most expensive build of just the engine.

I'm raising the BS flag very high for anyone 'realistically' making 650 RWHP with a 6.2L @ 12 psig even with cam & CNC heads. The math just doesn't support it. Neither does the dozens of SC engine combinations I've worked with.

An otherwise stock LSA with 12 psig will make 625 CRANK HP in my experience - but like I said, the lower compression allows better spark timing resulting in this power level. I've done many, many LS3's with same boost that will not clear 600 HP due to knock sensitivity with higher compression. An engine is a system - not just a pile of parts. All need to be considered together to optimize capability.

Remember - properly calibrated dyno's don't lie, but dyno operators do. And chassis dyno's are all over the place. Great for doing A vs B work - but horrid for absolute numbers. Changing your tire pressures can result in 20 HP (more with bias tires). Tell me the airflow rate and/or fuel flow rate and I can tell you how much power you can POTENTIALLY be making.

Thicker head gasket to lower compression - BAD idea! Ruin the quench in the chambers and make engine even more knock sensitive than it was with higher compression. Dished pistons for lower compression always keep quench of chamber for better flame front propagation.

Reason to run lower boost with cam and maybe CNC heads: Better adiabatic efficiency. You stated you want to road race this combination - not gonna happen with 12 psig on stock compression ratio. Well, at least not making full power for anything more than part of lap 1. Plot where you are asking SC to operate on compressor map and look at drive losses & adiabatic efficiency then figure out how many kW cooling system you'll need for not just engine, but intercooler as well. Best to optimize efficiency to get the power. Drag racers can get away with some crazy crap (and can run air-to-ice intercoolers) - but they have no duty-cycle to contend with like road racers or even Auto-X.

If you are running an LSA SC, why not run LSA CTSV accessory drive? I assume you are talking old (2004-2007) CTSV accessory drive - which means you are limited to 6-rib drive belt - for everything including SC (unless re-pulley everything to 8-rib - more $$). 6-rib will not drive the 1900 TVS SC without slipping @ 12 psig. There is a reason factory drive is 8-rib (and that is for SC alone).

Yes, VVT can broaden torque band. But with a positive displacement SC - you'll have all the torque band you'll need. Up to you - but I'd ditch it.

Yes Thomson can calibrate any of these combinations - I do most of their calibration work so I can answer that.

Matt @ Sled Alley does exceptional work - reason you see Mark's cars there frequently. He also has a '67 Camaro we did a 418 SC engine for that made great power. And an old Caddie with an LSA in it we did.

Dave

[RLJ676]

Originally Posted by mikels

I'm raising the BS flag very high for anyone 'realistically' making 650 RWHP with a 6.2L @ 12 psig even with cam & CNC heads. The math just doesn't support it. Neither does the dozens of SC engine combinations I've worked with.

An otherwise stock LSA with 12 psig will make 625 CRANK HP in my experience - but like I said, the lower compression allows better spark timing resulting in this power level. I've done many, many LS3's with same boost that will not clear 600 HP due to knock sensitivity with higher compression. An engine is a system - not just a pile of parts. All need to be considered together to optimize capability.

Remember - properly calibrated dyno's don't lie, but dyno operators do. And chassis dyno's are all over the place. Great for doing A vs B work - but horrid for absolute numbers. Changing your tire pressures can result in 20 HP (more with bias tires). Tell me the airflow rate and/or fuel flow rate and I can tell you how much power you can POTENTIALLY be making.

Thicker head gasket to lower compression - BAD idea! Ruin the quench in the chambers and make engine even more knock sensitive than it was with higher compression. Dished pistons for lower compression always keep quench of chamber for better flame front propagation.

Reason to run lower boost with cam and maybe CNC heads: Better adiabatic efficiency. You stated you want to road race this combination - not gonna happen with 12 psig on stock compression ratio. Well, at least not making full power for anything more than part of lap 1. Plot where you are asking SC to operate on compressor map and look at drive losses & adiabatic efficiency then figure out how many kW cooling system you'll need for not just engine, but intercooler as well. Best to optimize efficiency to get the power. Drag racers can get away with some crazy crap (and can run air-to-ice intercoolers) - but they have no duty-cycle to contend with like road racers or even Auto-X.

If you are running an LSA SC, why not run LSA CTSV accessory drive? I assume you are talking old (2004-2007) CTSV accessory drive - which means you are limited to 6-rib drive belt - for everything including SC (unless re-pulley everything to 8-rib - more $$). 6-rib will not drive the 1900 TVS SC without slipping @ 12 psig. There is a reason factory drive is 8-rib (and that is for SC alone).

Yes, VVT can broaden torque band. But with a positive displacement SC - you'll have all the torque band you'll need. Up to you - but I'd ditch it.

Yes Thomson can calibrate any of these combinations - I do most of their calibration work so I can answer that.

Matt @ Sled Alley does exceptional work - reason you see Mark's cars there frequently. He also has a '67 Camaro we did a 418 SC engine for that made great power. And an old Caddie with an LSA in it we did.

Dave

I can't vouch for their dyno's, hell could be just internet boasting of RWHP. Also likely they're tuned pretty "risky". I was more concerned on have they popped or not and how many miles... And I'd be doing rare HPDE's so not real road racing I'd say. I've read your threads on Mark's cars...I'm not at that level of use so my cooling will be much more street than track.

I just talked to Matt and recommended I talk to you actually and I mentioned I think I was already lol.

I am talking about the GMPP CTSV FEAD, there's a part number that puts the alternator up top like a vette but is otherwise the same. It's 8 rib for sure. http://paceperformance.com/i-1999062...em-w-o-ac.html

So I have access to the engineer for water pumps (we can all put together location and guess where I work haha) and unfortunately it's been years since he worked Gen IV stuff, but we determined that anything that definitely clears the VVT cover is truck spacing. However, he said there is sufficient material to possibly create clearance in the back of a CTS V pump, but we weren't sure how much needs to come out. I'm going to try and look at the math tomorrow. and see what's possible.

So assuming I can solve the water pump issues, but am stuck at 10.5 how much power would you guesstimate at stock LSA 9 lbs vs 12 (stock L92 heads, LS7 throttle body unless that's limiting too)? How about then with a LS9 cam and no VVT same two options? Which leads to what's the gain on dropping below 10 (or whatever's optimal) w/ dished pistons? I didn't want to take apart the short block but everything's about tradeoffs right?

Thanks again, sorry for so many questions... Just kinda wanted to figure out how to be "first" w VVT and FI, but if not worth it it's not worth it. Like I said if I had the dough a LS7/2.3 blower setup would be in the works haha.

[DavidBoren]

Is the truck/ vvt water pump the only accessory that is out of alignment with the CTS-V/ LSA drive? If so...

Electric water pump. The end.

[RLJ676]

Originally Posted by DavidBoren

Is the truck/ vvt water pump the only accessory that is out of alignment with the CTS-V/ LSA drive? If so...

Electric water pump. The end.

Yep, everything else would come out of the kit I linked above. The VVT cover sticks out further which is why the normal "car" pumps don't fit as cast. That's definitely an easier solution, hadn't thought of it I gues. thanks.

Waiting to see Dave's thoughts on the above, I'm definitely getting the feeling he's seeing no advantage to a VVT. Having owned a stock CTS-V I can attest there isn't a lack of torque w/ this PD blower on a 6.2... I just want to make more power than that haha.

[DavidBoren]

I would imagine that the vvt would improve the driveability, no matter what. No, you don't need it on a positive displacement blower motor. You probably don't need a positive displacement blower motor, for that matter, either.

But things like blowers and boost in these applications make the driving experience more enjoyable. And wouldn't the vvt just make all that power a little bit easier to drive? Wouldn't it just be that much more enjoyable?

Except for maybe limiting the ultimate top end numbers, what disadvantage is there to keeping the vvt?

Would you be willing to not have 700hp at the crank, for a really easy to drive 650 crank horsepower engine?

[RLJ676]

That's the math I'm trying to figure out exactly, and what the costs are.

If I can get a really fun/responsive setup with stock L92 + LSA at stock boost with a good tune that could be the way to go. Otherwise I'll go w/ a LS9 cam and stock boost if that's best as that is a known quantity and affordable, not to mention I like using GM parts where possible haha.

Only bragging rights I'd want is to have more at the wheels then a buddy w/ a lingenfelter setup on his CTS-V...where is upgrade cost more than my engine will (not the whole swap). I am already confident I can outpower his Gallardo lol.

No matter what it will exceed my tires and driving ability for most situations... but since when do we care about that?

[DavidBoren]

That's what I gathered from your previous posts. That's why I think that whatever power may come from sticking that LSA blower on your longblock, with your stock vvt cam, I think will be plenty fun.

It will be the cheapest route, as well. Stock vvt cam, LSA blower, and a good tune. Drive that, see if you have room for more boost or a bigger cam.

It's going to be a beast no matter what.

[RLJ676]

Originally Posted by DavidBoren

That's what I gathered from your previous posts. That's why I think that whatever power may come from sticking that LSA blower on your longblock, with your stock vvt cam, I think will be plenty fun.

It will be the cheapest route, as well. Stock vvt cam, LSA blower, and a good tune. Drive that, see if you have room for more boost or a bigger cam.

It's going to be a beast no matter what.

Realistically I think this is correct. Just don't want to leave a lot on the table if all it takes is a LS9 cam haha. So many variables though... All I know is I can't wait for good power I don't have to warm up for 5 minutes and gets 8 mpg!

[no go nova]

Why not port the stock blower while you have it off? Also if you run a good heat exchanger to keep the charge cool shouldn't that help with stopping knock? And a water/meth injection system that maybe engages at 8psi with a 5 gal tank system so you can run 93 no problem? Just get a good system. maybe pick up a used blower cam thats vvt or non vvt, with new springs and dont forget to do the trunnion upgrade while your at it.