Shadow1478

Been picking around the forums and trying to get accurate information on current and future plans for my build:
Let me start with some back info:

-LS3 Grand Sport M6 (dry sump)
-Magnuson TVS2300 w/ 3.1" upper pulley
-Stock lower pulley (7.5"?)
-1 7/8" Headers
-Mishimoto Radiator
-DW 65lb injectors (I think; have not pulled injectors yet but that's what I was told and what the HP tuners file appears to have)
Unsure if tuned on 91 or 93, i have 93 available to me

Car supposedly makes ~550whp
with that being said its slower on the street than my LS2 H/C/I ~500whp c6...
Have not gotten to a dyno yet but the LS2 holds up close with my buddies Heads/cam, Magnuson LS3 Camaro and the LS3 TVS 2300 Grand Sport significantly gets pulled on by that camaro...
Have suspicion the tune file needs cleaned up as it was street tuned and also has no dyno sheet :/

As I bought the car with the mods done, I don't know what upper pulley comes stock on these magnuson TVS 2300 kits. I'm led to believe that it may be a 3.6" pulley?

Looking to get around 600-650whp area. on 93, maybe adding e85, fuel pump the following season
So far I want to/plan on doing a cam and smaller pulley. I hear the TVS 2300 are efficient up to about 22k rpm. I have been looking at possibly a 2.6 upper.
Definitely would like to skip doing heads and dropping the cradle/pulling the blower off.

Should I upgrade cold air intake, port the TB and possibly snout? Is that unnecessary for this HP range? 6 Rib belt setup on it, am I able to run a 2.6 upper on stock lower on 6 rib or is that at/past the limitations for belt tension? I am not completely against going 8 rib if absolutely necessary.
Struggling to find info online other than some Zr1 posts but I was unsure how exact they compare to my setup.

Any advise, recommendations or similar setups are welcomed.

Thanks

old motorhead

Which Maggie TVS2300 do you have? Is there a shaft on the passenger side or the blower running front to rear? Stock or aftermarket hood?

Shadow1478

I believe it is the newer style.. No jackshaft. No aftermarket hood. Installed March 2020.

old motorhead

That leads me to believe that you have the Heartbeat. If that's the case, a 3.1" pulley is about the smallest that will fit. How much boost do you see? Should be well north of 10psi. A good running HCI LS2 shouldn't even be in the same zip code as a properly running LS3 with 10+ pounds of boost.

My last Vette was a Grand Sport with Heartbeat, mild cam, and all of the bolt ons. It had an 81mm blower pulley which slightly smaller than 3.2". It made 664/612 at the wheels. Basically, set up like yours. Only difference being the blower cam.

I believe the Heartbeats came with a 96mm pulley. About 3.8"

You need to have yours looked over by someone who knows what they're looking at. As in a shop that's built and tuned numerous Vettes set up like yours.

Shadow1478

Well that's concerning. Could it be pulling a bunch of timing out of it for some reason? Obviously down low the torque is night and day compared to my HCI LS2 but up top its disappointing to say the least. With this pulley it should still be pulling like a train up top in comparison to the LS2 then if you had a similar size pulley with just a cam. Again, I was told it makes "550" which I find hard to believe from the butt dyno, but seems like it should be making at least that power based on the pulley size?

New to FI, seems impossible that I would pick up another 100 wheel with just a cam (assuming I have the fuel available) were you on pump 93 or e85?

I hope that the clutch isn't slipping, supposedly has a twin disc McLeod in it. Hate the clutch, engagement is minimal and clutch pedal has 2" of dead spot up top before the pedal spring even begins to compress. Love my LS7 clutch in my LS2 car, much much firmer.


Am I able to read boost with a DashLogic off the ECU? My tuner wants me to install wide bands and hook up HP tuners to see what we are working with before this winter when I do mods and throw it on the dyno.

Temps are great; nice and cool oil and coolant.
I know just enough to be dangerous.. Not a pro tuner by any means but I'm trying to learn. My head has been spinning trying to figure out whats going on with this thing.

Thanks

old motorhead

TVS blown engines "pull" a little differently than N/A or centrifugal blown engines. They get to max boost in the 2000rpm range. Boost level remains mostly level from there on up. Power probably isn't going down up top, but it's not like a centri where boost and power are increasing with RPM.

No, you won't get a hundred more HP with a mild blower cam. Wild assed guess would be 40 to 50. Mine was running on pump 93 with meth injection. The meth was worth all of 20 hp. Meth and TVS blowers really aren't a good match. If I put another TVS rig together, it will be running on mostly E fuels tuned for flex fuel. E fuels and TVS blowers ARE a really good match.

I trust your tuner did tune yours with a wide band in the tailpipe. I can't see how he would get the tune even close without that. Your tune may be short on timing, but I'd also bet it's crazy rich too. Both will kill power.

C6_Prodigy

If dashlogic can show the MAP reading, then you can subtract atmospheric pressure (14.7psi) from the reading to get your boost level.

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Shadow1478

Car came with a meth kit bolted in the trunk. Fuel line was not hooked up, unsure if they used it or not.. (could this play a factor in the conservative tune if they were mostly playing around with meth instead of pump fuel?)

I'll get some data on boost levels and see where this thing is sitting, but I agree, its probably got a ton of fuel in it and overly conservative timing.

Is it worth the money/is there going to be a noticeable power increase from aftermarket CAI, TB and possibly ported snout or with these numbers I'm shooting for are those mods unnecessary? How bout fueling, assuming I have enough injector, will I be able to get away with the stock pump in the low to mid 600whp range or will I need a secondary pump?

old motorhead

Over 550 rwhp and the stock throttle body starts becoming a restriction. I saw 4" of vacuum behind the throttle body between it and the blower. I checked between the throttle body and the air filter and there was no vacuum at WOT. That pretty much points to the throttle body as being the source of the restriction. That was at 660 rwhp. Get rid of the restriction and boost and power will go up.

If you're on the stock fuel pump, you don't have enough pump to supply low to mid 600's at the wheels. If you're going to have to upgrade the pump, it doesn't cost much more to go flex fuel. You'll need to upgrade injectors, but you may have to do that regardless. If you still have the ZR1 injectors that the Heartbeat comes with, they probably aren't good to mid 600's even on pump gas. With a blower cam, E85, and 10psi, low to mid 700's is very possible.

Shadow1478

Great info.
Any recommendations on fuel pump brand/setups?
Also wonder if there are any weak links around that 700whp area. Do the diff's hold up that power on the GS?

Side Note: Graphed MAP today. 9.2 lbs of boost (23.9psi)

C6_Prodigy

That's a healthy amount of boost and should be much quicker than the LS2 and Camaro you referenced. To confirm, you bought the car as-is?

If temps are good and boost is there, my next step would be to take it to a tuner or at the very least do some data logging and send it to a tuner for analysis. It doesn't add up that you have all the right parts and are seeing that level of boost at the MAP sensor but are not feeling it. Sounds like something in the tune, maybe pulling timing like you said.

old motorhead

Are you sure you have a 3.1" blower pulley? If it's a Magnuson pulley, it will have a part number on it that states the diameter of the pulley. It's stated in millimeters, and it may be on the back side of the pulley. Increments of 3 as in 96 93 90 87 84 or 81. Those are the only sizes I'm aware of that Magnuson manufactures for the Vette Heartbeat. If you do indeed have a 3.1" pulley, it's an aftermarket item and probably means you're experiencing belt slip, or your boost would be higher. That's assuming you're not up in the clouds somewhere at a really high altitude.

streetking408ys

As far as fuel system, you really really need to think about your goals. Realistic ones, as in if you achieve the 650rwhp mark for example.....are you going to then want to get to 750 rwhp and so on? E85 makes a big difference in fuel needs too. There is a point not far from your goal area where you should ditch the returnless non boost referenced type and get to a boost referenced return style. Sure there's a gray area in there where you can get by.....possibly for a long long time.....but you want to do it correctly....and correctly the 1st time will be most affordable.

For comparable cars I've built I've had great luck with dropping in a factory GM Z06 (LS7) fuel pump module. If you forsee any flex fuel/ E85 in the car's future then I'd go with a Racetronix Ethanol compatible unit instead. East Coast Supercharging (ECS) Stage 1 fuel system which is a Tee'd in secondary pump triggered off boost VIA a Hobb's switch. Again if you have E85 in your future you'd want ECS's E85 compatible version. Run the Racetronix hotwire kit for the fuel pump. If you need to leave the door open for E85, you'll be looking at ID1300's.
As you turn the boost up, you'll need to stay on top of IAT control so you're not fighting diminishing returns. 8 rib belt is the minimum. 10% OD IW crank so you can run a larger pulley up top @ the same blower speed, underdrive your alternator to avoid overspinning it. The 10%OD crank will help keep charging the same at idle plus you're talking cam which will bring about a higher idle speed netting you about the same alternator shaft speed @ idle compared to stock.

Shadow1478

Purchased as is.


3.1" ZPE Griptec upper pulley if I'm reading that 1 correctly.
(6rib setup)

Sea level altitude.

Shadow1478

I think I'm most interested in doing a cam, 10% OD crank, fuel pump and maybe flex fuel, tentative to feedback. 8 rib system while the HB is being replaced. The car is mostly a street car. Would like to do some weekend drag racing with it..Not necessarily looking for crazy power. I hear the 650whp range is the sweet spot for a street car before it becomes a little much. I run r888r and don't necessarily plan on running a drag radial. I don't mind some spinning, its expected on the street.

With my tuner's HP tuners data and the original tuner's memory (before pulling an injector) it appears to have DW 700cc (65lb) @3bar which if I am understanding and heard correctly, which I may not, flow ~85lbs (900cc) at 4bar which appears to be the pressure a corvette produces (stock at least, unsure about aftermarket). IF that is correct, does this injector cover me for 650-700whp range on 93/E85? Don't have any plans on making this car faster than that anytime soon.

Curious to look into the alternator pulley sizing more.. Do you think that's necessary with a 10% OD crank if idle is kept around 850 idle?

old motorhead

You either have an underdriven crank pulley or a whole bunch of belt slip.

Shadow1478

Data logged MAP again. Was holding consistent at 9lbs. Underdrive is stock. Unsure how much, if any, correlation there is to MAP reading and belt slip.

Need to dyno and go from there..
See where this things at before going forward.

grocerygetter

so when you say “under drive” it reads like that is what you are calling the lower crank pulley. If so, stock means it’s stock diameter. When we all say under drive we mean that it’s xx% under driven to slow down accessories driven from crank pulley to typically free up a few horsepower or make rev a bit snappier. I don’t know many cases where someone would under drive a crank pulley with a blower attached. I know folks will over drive them so the upper pulley doesn’t have to be as small to help with better belt wrap.
just trying to help with terminology used here, that’s all.

old motorhead

I had a really hard time eliminating belt slip on my Heartbeat setup. I had a bigger pulley than you and a blower cam. Both of which will lower boost compared to how your setup. My boost peaked at 9.9psi at about 2500rpm and stayed right at 9.5psi through the run. Short of a worn out blower or other mechanical issues, you should be north of 11psi. Assuming low altitude.

The first thing I'd do is to make sure your serp belt isn't too long. Your belt stretches as boost and rpm go up. The belt also stretches with age. Your belt may seem nice and tight now. That's may not be the case once you go WOT. If you can compress the tensioner much at all, your belt is too long. You need to use the shortest belt you can get on there....with two people. That way the tensioner has a long stroke before losing the ability to keep the belt tight. This video is probably worth a thousand of my words:
Video: Watch a Supercharger Belt Tensioner at Work| Videos | Grassroots Motorsports

Also had good luck with the Continental Gatorback belt Serpentine Poly-V The Quiet Belt Gatorback CONTINENTAL ELITE/GOODYEAR 4060592 | eBay

streetking408ys

6 RIB is certainly a waste of time. 8 rib or 10 rib 10% OD IW and don't look back.