L92 Longblock + LSA Supercharger - What Cam?

[RLJ676]

So I just bought a L92 long block, only 9k miles on it. I am on some type of budget so I don't want to dump tons of money in that I don't need to for my goals. I want 650-700 crank for a street car, rare track days (road or 1/4). It's a 72 Camaro pro-touring so I don't want the "cheapest" build that hurts resale haha.

So with this combo can I just keep the stock VVT cam and still make my goals? I'm thinking overdrive balancer pulley from Texas Speed (that's a no brainer since I need to swap out the balancer anyways), maybe stock pulley on blower. Given the compression is 10.5 I think this should bring it up to 12-13 lbs of boost and be about as much as I want/need?

I'll use the ZL1 lid and a LS7 throttle body, mid length swap headers (for ground clearance).

So do I need a cam, should I just use a LS9 and drop VVT for ease of tuning? After springs and VVT delete that's about $450 (unless I can use LS6 or similar GM springs?). An upgraded VVT based cam/springs seems to cost at least $700?

Any injector recommendations, best bang for buck? I also will need a harness/ecm/tune. Thinking the LSA or 9 kit from GMPP with a good tune, anyone know one in Det area?

I also posted on ls1tech, but know there's some real good engine guys here.

Title edited - Cam chosen...looking for other advice later in thread. Went with a BTR stage III cam and VVT delete.

[mikels]

Originally Posted by RLJ676

So I just bought a L92 long block, only 9k miles on it. I am on some type of budget so I don't want to dump tons of money in that I don't need to for my goals. I want 650-700 crank for a street car, rare track days (road or 1/4). It's a 72 Camaro pro-touring so I don't want the "cheapest" build that hurts resale haha.

So with this combo can I just keep the stock VVT cam and still make my goals? I'm thinking overdrive balancer pulley from Texas Speed (that's a no brainer since I need to swap out the balancer anyways), maybe stock pulley on blower. Given the compression is 10.5 I think this should bring it up to 12-13 lbs of boost and be about as much as I want/need?

I'll use the ZL1 lid and a LS7 throttle body, mid length swap headers (for ground clearance).

So do I need a cam, should I just use a LS9 and drop VVT for ease of tuning? After springs and VVT delete that's about $450 (unless I can use LS6 or similar GM springs?). An upgraded VVT based cam/springs seems to cost at least $700?

Any injector recommendations, best bang for buck? I also will need a harness/ecm/tune. Thinking the LSA or 9 kit from GMPP with a good tune, anyone know one in Det area?

I also posted on ls1tech, but know there's some real good engine guys here.

I think ~625-650HP is a more realistic goal with what you have to work with. Compression is a little high to expect 10-12 psig boost with pump gas. Issue will be have to retard timing so much to suppress detonation at those boost levels that will likely make less power than lower boost and better optimized spark.

LPE GT9 cam works great in LSA's and LS9's and should work great with what you have as well (just need to check piston-to-valve clearance with higher CR pistons).

CNC porting of heads helps as well (depending on budget).

If running LSA supercharger, just buy the LSA GMPP kit - includes everything needed.

GMPP LSA FEAD (Front End Accessory Drive) can be purchased as well (fully validated OEM accessory drive).

Injector Dynamics ID725 injectors. Not cheap - but best injectors I've found.

Thomson Automotive in Wixom if you are looking for location in Detroit area to get this work done.

Dave

[DavidBoren]

Personally, I would retain the vvt. The more aggressive of the vvt cams available from comp cams is actually very comparable to the LS9 cam.

LSA: 198/216 .480/.480
LS9: 211/230 .562/.558
Comp vvt cam: 218/222 .566/.578

All with a ~114 split.

I think the benefits of the vvt would be worth keeping.

[mikels]

Originally Posted by DavidBoren

Personally, I would retain the vvt. The more aggressive of the vvt cams available from comp cams is actually very comparable to the LS9 cam.

LSA: 198/216 .480/.480
LS9: 211/230 .562/.558
Comp vvt cam: 218/222 .566/.578

All with a ~114 split.

I think the benefits of the vvt would be worth keeping.

Mixed bag here - depends on your goals.

With HP desired, will not make it even close with these milder cams. Running a more aggressive cam with VVT requires a phase limiter to prevent piston to valve clearance issues. Once you do that, benefits of VVT are greatly diminished.

This is a dual-equal VVT as well (single cam) - not a DOHC or even cam-in-cam (ala Viper). Benefits of VVT are already not nearly as good with dual-equal.

VVT benefits include dilution (for FE and emissions) as well as broadening TQ band. Seeking these power levels means FE is not a top priority. Going in an older car - so emissions not an issue. The need to broaden TQ band on a positive displacement SC engine is also not an issue. Depending on front end clearance, VVT hardware requires truck FEAD (front end accessory drive) or at least spacing further away from block. And more s**t = more s**t that breaks.

I love VVT - especially with DOHC - but need for it in this application I'd question.

Dave

[DavidBoren]

The OP's mentioned power goals are right around the LS9's listed power. So, I was assuming that a comparable cam to the LS9 cam could get him where he wants to be, and the vvt would help improve driveability.

Even a limited cam phaser should still provide noticeable gains in driving a 600+rwhp vehicle on the street, right?

From my very limited understanding, people seldomly install/ lock in more than 4° advance or retard in their cam anyways, so if the vvt, even in its limited state with the more aggressive cam, only offers a plus or minus 4° difference, isn't that still going to help?

Or am I missing something entirely? It wouldn't be the first time. Probably won't be the last, either.

[Jr]

To the OP,

Mikels/Dave knows these motors really well. Listen to what he has to say. He could also build it for you, too.

Dave,
Why don't you embed a link to your website in your signature?

[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!

[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.

[DavidBoren]

The vvt and blower combination just makes sense to me, as well. Granted, I do not have any actual experience with boosting LS motors, so it's probably best to listen to the man with real knowledge on this topic.

The price of the vvt delete parts, and the compatibility of the vvt timing cover with the blower accessory drive will be a huge determining factor. If the blower drive doesn't line up with the vvt cover, it's time to swap cams, and nix the vvt. If it lines up, then there's no reason to delete it, in my opinion. Assuming that the valve springs used with vvt can actually support boost. I don't know if the vvt requires special springs, or if they are stiff enough for 12psi.

[RLJ676]

Originally Posted by DavidBoren

The vvt and blower combination just makes sense to me, as well. Granted, I do not have any actual experience with boosting LS motors, so it's probably best to listen to the man with real knowledge on this topic.

The price of the vvt delete parts, and the compatibility of the vvt timing cover with the blower accessory drive will be a huge determining factor. If the blower drive doesn't line up with the vvt cover, it's time to swap cams, and nix the vvt. If it lines up, then there's no reason to delete it, in my opinion. Assuming that the valve springs used with vvt can actually support boost. I don't know if the vvt requires special springs, or if they are stiff enough for 12psi.

Right, just seems dumb to throw away a good power making technology haha.

I'm a quick learner, but still have a lot to learn on all this. But given some simple math like 10 hp per lb of boost I think even a stock cam VVT setup plus 12 lbs gets me to my goal w/ a conservative tune for 93 octane. If I can lower my compression a bit even better. I know it will build heat if I beat on it on a road course for long, etc. Not really intended use though. I also think on stock LSA boost it won't make my power goal without a big cam, so this is the most $$ efficient way to get there.

I get the idea to "overbuild" and be bulletproof, but I also don't have a super expensive short block. I could spend $2k overbuilding a $2400 shortblock lol, or just hope I don't blow it up and if I do buy another and turn down the boost (or build that second one appropriately for more money). Not sure if that makes sense to anyone else, but it's my view on paying for warranty etc also. I'll take some risk I may have to spend more money in the future rather than for sure spend a decent portion of it up front.