~300WHP build with TVS; Part list advice?
 

To recap, I picked up a 2006 SS/SC with 134k miles about a month ago. Previous owner replaced the timing and balance shaft components after the factor timing tensioner broke, and he was never able to get it running after this. he suspected bent valves, but I never did find the real culprit. I ended up pulling the heading, taking to a shop to be cleaned, pressure tested, get a valve job, and be resurfaced. While it's apart, I'm giving some serious thought to replacing the piston rings, just to be on the safe side. It would also give me a chance to inspect for cracks/ringland issues, etc. Not looking to go billet rods/pistons, and prefer to stick with my factory existing pistons/rods.

So beyond that, I figured I should go ahead and start ordering some parts for the build I want to do with this engine. Long story short, this engine will be pulled from the car in the next 6-12 months to be used in a DF Goblin, but I want to play with the car first. Looking for general advice on this list, if there is anything else I should be considering, if something I'm planning is pointless, etc.

TVS 1320 Supercharger - $2500 (ZZP and OTTP both sell for $2500; is there anywhere I can get it cheaper??)
ZZP Ecotec Shorty Header - $170 (shorty because the car has custom catback already, and I'll need the stock manifold or shorty when the engine goes in a kit car)
Siemens 80# Injectors - $170 (tuning on 93 octane, so 80# should be plenty, E-85 is available locally but I'm not ready to commit to tuning for it)
ZZP LSJ Injector Harness - $27 (needed for the injectors)
ZZP Dual Pass Endplate - $110
ZZP Phenolic Intake Spacer - $100 (have heard good things, figured it'd be worth it)
ARP Head Studs - $145 (This is current price on ZZP; can they be had cheaper elsewhere??)

Obviously I will need a new head gasket, but not sure if I should go with a Cometic (and if so, which thickness??) or OEM.

I'm also considering:
ZZP Billet Engine Mount - $150 (probably will wait on this until I go to build the kit car)
LS4 Throttle Body - $225 (on the fence about this -- I hear this gives gains, but the throttle is pretty touchy and that may not be a good thing in a 1600 lb kit car)

Thoughts on the parts listed above? Is there anything else I should add? Let me note that I'm not interested in Opt B because I don't want to deal with it on the kit car, and I don't want to add/swap a h/e on the Cobalt since I likely won't be able to use it on the kit car.

I considered heavier valve springs, but I really don't see the benefit with stock cams. I think a 6500-7000 redline is going to be plenty for this build, so that also means I shouldn't need to worry about neutral balance shafts.

Lastly, the TVS 1320 (at least from ZZP) comes with a 80mm/3.1" pulley. Thinking about dropping to a 2.9" instead, which I THINK would be perfectly fine with the mods mentioned above. Could/Should I consider a smaller pulley, say a 2.8" or 2.75"? I'm honestly not sure the limits fo the TVS with stock heads.

To be clear with my end goal, the kit car won't be a daily driver. It will be a weekend/fun car, and something I occasionally take to the drag strip for fun (no real competitive drag racing). If I can hit 320WHP with the above (and a smaller TVS 1320 pulley), I would be ecstatic. 300WHP, I'd be happy and 100% satisfied. 280WHP would still be acceptable.

Head is off the car already, and should be going to a machine shop in the next couple of days. Planning to pretty much order everything except for the TVS 1320 this week. TVS 1320 will likely have to wait a couple weeks, but not a big deal...unless I can find a deal on a used one around here/eBay/FB??

Thanks!!

Good to know, and will probably solidify my decision not to go E85. I was digging through the dyno threads and overlooked that when looking at LSJ's with the 1320 and E85.

I would not let injector size deter you from running E85. you can hit that number safely and easier running E85 over pump gas.

Other than large injectors, is there anything else I'd need to do before tuning E85? Like do I need a bigger fuel pump, etc?

You should be able to make 300 whp on 93 and water/methanol injection if you wanted. E85 is a more robust option and you should be able to make even more power but just wanted to throw that out there. I've made at least 310whp on 91 and w/m injection. The reason I kept mine on pump gas, instead of E85, is that E85 isn't readily available in my area and I want to be able to take my car down the road and be able to fuel up pretty much anywhere.

Is boost reference fuel pressure mainly to help with idle?

No, it's for higher boost applications. Simplified version, 15psi in intake manifold with 52psi injector pressure nets you 37psi at the fuel injector, boost reference will increase the fuel pressure to maintain the 52psi at the injector allowing more fuel to spray

Yeah I hear you there just thought with TVS application there's enough injector there to compensate for pressure drop. Way I read the ZZP product description they actually have you drop the fuel pressure to 42 psi at idle then with the boost reference it raises 1:1 with boost. So if stock is 60 psi then you would need 18psi of boost before the boost reference fuel pressure would even be back up to stock. If I'm interpreting correctly they are using this regulator more to drop pressure at idle than to raise it for boost. Of course there are probably tuning advantages to having constant relative injector fuel pressure but didn't know if it actually helped deliver more fuel than stock or not, specifically with no more than 18 psi of boost.

It's been awhile since I've looked at the boost reference system on an LSJ, but isn't the other reason for it to run a return style system? (I'm forgetting if the LSJ in stock form has a return style fuel system or not).

People do also use this kit to run a return style system even though ZZP claims it has no performance advantage. According to their product description they just offer it because people asked for it.

you have to think of fuel pressure as the differential pressure, the difference between the pressure in the rail vs the pressure in the intake manifold. stock rail pressure is 58psi. now at idle, you have around 18" of vacuum, that works out to roughly 9 psi of vacuum, so that makes the differential pressure 67 psi. now looking at stock boost levels around 12psi, your differential pressure is dropping to 46 psi. now this is a perfectly fine operating pressure for most injectors, most being flow rated at 43.5psi, but as boost increases your pressure now decrease. 15psi boost gives you 43psi, 20 psi boost gives you 38psi. once you start getting that low, spray pattern is affected. and keep in mind this is assuming you maintain perfect 58psi rail pressure through the whole range, something that typically doesnt happen. my car (m62, 2.7 and 60lb) ill see a drop as much as 4 psi at the rail during a pull, meaning at roughly 17psi boost my differential pressure isnt 41 psi, its 37psi. this is due to the regulator being so far away from the rail, it doesnt take pressure drop of the feed line into account.

the ecm does compensate for the differential pressure changes, and the dropping differential pressure is why our cars need such large injectors. a 60lb injector in a rising rate system is enough injector to support 400hp, and in our cars we are nearly maxed at 300hp. going larger and larger on the injectors to make up for a poor fuel system is a band-aid fix. dropping 160 lb/hr injectors in to run e85 imo is just dumb, thats enough injector to support 750 hp (on e85).

the proper thing to do is run a rising rate regulator and appropriate sized injectors. if they have you set the regulator at 42psi, thats a decent starting point, the injectors have a good spray pattern and good atomization at that pressure. remember, your rail pressure goes up and down with manifold pressure, so your differential pressure is goes to be 42 psi all the time. 42 psi at idle (not 67 like stock) and 42psi at 20psi boost (not 38). if you want a higher pressure, you can adjust for that, you could run 58 psi rail pressure (set with the vacuum line unhooked), but you have to remember that as fuel pressure goes up, pump flow goes down. 58psi base fuel pressure + 20psi boost ends up at 78psi, and the problem there is you run into the cracking pressure of the pump (many efi pumps will deadhead 90+ psi, but the flow drops off so much above a certain point it cant maintain the pressure). this is why you go with a lower base pressure.

Yeah I understand the differential pressure I was just assuming stock ran at 60 psi and kept up with flow demands. With TVS I max out around 18 psi so my lowest differential pressure would be 42psi. From this I decided the boost reference fuel pressure regulator wouldn't really do anything to add fueling up top but help pull fuel pressure with lower manifold pressures down low. If my actual constant stock fuel pressure is lower than 60 psi than this wouldn't hold true.

I've been trying to decide if I need boost reference fuel pressure regulator with my current project running 91 octane through 65lb injectors. Max boost 18-20 psi. This is why I've been intent on figuring this all out.

650cc injectors is enough to run E85 on an LSJ?

sure, if the pulley is big enough.



OP;
TVS + civilian fuel = disappointment.

Corn is a must unless you want to drive around on race gas.

I made the 444 whp using 80 lb siemens, 93 octane + water/meth, 25 psi boost; the fuel system is the bottle necking (looking at FP transducer) and the injector duty is also in the 90% (at 11.3:1 AFR target). This is a stock Solstice fuel system, the only upgrade here is a '700 hp' in-tank pump. I have all the parts in stock for the new setup: 350 lph Deatsch pump in a surge tank, new lines, BRFPR return system, big injector rail. I'm sticking to 93 pump.

I hit 315whp on my tvs built.

Stock intake with a filter will be fine with the bottom of the airbox removed
60lb injectors
ZZP BRFPR
Badmab shorty header
2.5 catless downpipe
2.5 corsa catback
TVS with 2.9 pulley
Stage 2 snow performance water/meth kit

All set up for 93 pump gas

Thats all I had as far as power upgrades. I had other items for supporting mods like GMP clutch upgrade, Dual Pass endplate, Option B setup, front mount heat exchanger, axles, upgraded motor and trans mounts etc etc but that is all i had as far as power upgrades. All dyno tuned on a dyno jet. Stock block, stock head.

Tycoon bob, E85 or premium pump + water/meth will both easily get you where you want to be. Both options have their pros and cons.

Pros of w/m injection:

• Can fuel up almost anywhere
• Retain good fuel mileage
• Significantly less demand on primary fueling system pump/injectors

Cons of w/m injection:

• Have to bring w/m mix with you plus have adequate reservoirs
• Have to take extra steps to ensure fail-safe if w/m system fails to prevent detonation
• Adds system and tuning complexity

Pros of E85:

• No secondary system, primary fueling only
• Robust, less complexity
• More combustion chamber cooling

Cons of E85:

• Fuel alcohol percentage at pumps inconsistent
• Less availability of fuel
• Heavily reliant on high flowing fuel system
• Poor gas mileage

Of course this doesn't cover everything but a short summary of what comes to mind.

I really do appreciate all the replies, here. This is definitely turned into a "go ethanol" conversation, which is fine. There are 3 stations in my town with E-85, and according a few folks in a local FB group, the alcohol content is around 78%. My only concern with going ethanol is availability if I head out of town, which will happen occasionally. This car definitely will not be a DD. It is purely a toy, and a toy that will be become an even smaller toy later this year or early next (DF Goblin). It won't get driven in the winter, will be garage kept, and probably see fewer than 5k miles per year. But if I take a road trip, I will have to take extra caution to plan out fuel stops with ethanol.

Now that aside, I've placed a few orders for parts already. Ordered a dual pass endplate, Siemens 80# injectors, and harness, new head bolts (didn't want to pay for ARP head studs), and have a solid lead on a used TVS 1320 for $1300, shipped. Shorty headers will likely wait a bit, but I don't think that will make a big difference for me anyway.

Tuning wise, I'm not having much luck finding anything with an hour and a half of me. So my initial tune will probably involve me sending my PCM to ZZP, getting them to flash a tune, and send it back. From there, I guess I will buy HPT and start learning. But hopefully the ZZP tune can make the car at least drivable for me.

So with that all said, I should be able to send my PCM to ZZP, have them flash it for E-85 with my TVS blower, 80# injectors, K&N CAI, stock TB, and be good to go? Nothing additional will be needed? Just drain the existing fuel out of my tank and fuel lines, and fill er up with E85? Is it really that simple??

Get a hold of zzp and a copy of hptuners and have them remove tune you. You should add a wideband into your mod list, you'll need one for proper WOT tuning and it's always a good idea to keep an eye on how the AFR is when getting on it. If you plan on road racing the goblin you might consider an EGT gauge as well.

you can run 80s with a tvs on e but power will top out around 330hp you could run a set of 120lb/hr injectors and that would be a better choice you don't really need 160lb/hr injectors unless you will be running ported head/cams or both and you should run a return fuel system it will help keep bigger injectors in check at idle although the tvs shines best on e you can still do somewhat decent on 93 you can swap to a gas tune for your over the road trips and run a stock headgasket

40% is good considering your running a 2.4 and a tvs im at 70% idc anf your friend was on a happy dyno