[cmitchell17]

Originally Posted by 6spdhyperblue

That’s true. It’s good to have the option if we need it


Is anyone going to try the intake cover?

Yeah but doesn't the cover say "Corvette" on it? haha

[6spdhyperblue]

I’m thinking bondo, gloss black, white camaro decal, finished with clear. Not sure what to do about the logo


My manifold comes Monday. Will mod it, port it, and zero in the tune. If there’s no rain I’ll have track results next Friday with the LT5 throttle body.

[6spdhyperblue]

Well manifold came in early and got it all ported. ordered gaskets from rockauto and guess what..sent only 7 out of 8! Thanks rockauto!

Anyway got the ports all squared up and the snout opened up for the LT5 throttle body. Sanded down the ridges on the bottom to clear the hpfp and drilled and tapped fitting on the back

This manifold is really nice

[Booher]

Did you have to ditch the oem gasket for the throttle body to get it to fit correctly? How about opening up any of the mounting bolt holes, did you have to open those up? Thanks for working out all the bugs and issues for us waiting on new stock to come in.

[Purplt1]

Originally Posted by Booher

Did you have to ditch the oem gasket for the throttle body to get it to fit correctly? How about opening up any of the mounting bolt holes, did you have to open those up? Thanks for working out all the bugs and issues for us waiting on new stock to come in.

To correctly fit the 95mm you will have to port into the o ring groove. Just use an adapter plate and comes with a paper gasket to seal up to the manifold.

[6spdhyperblue]

I used a soler adapter and opened the adapter and the snout to just leave a bit of plastic before reaching the ring. Yes the ring is still there and functional

Edit:Rockauto screwed me pretty good. Going to use the extra time to up the grit on the cartridge rolls and smooth the ports out more. Also wiring the wideband back in for validation.

It took over six hours to port the intake. The runners are nice but are pretty wavy in stock form, also it seems like the snout has more meat on it so it can be opened up more than the LT1 intake. I spent a lot of time opening that up. I had to be careful not to get it too thin but I’m really happy with how it turned out.k

I have a hard time seeing this port job being only worth 3hp. gpi is advertising their port job worth only that much. Maybe theirs is really cleaning up flashing/ridges and not reshaping? They are charging $300 where renowned porters are getting $450-$550 just for the porting service. I am thinking there’s more to it. This is probably worth closer to 10 rear wheel

[s346k]

Originally Posted by 6spdhyperblue

I have a hard time seeing this port job being only worth 3hp. gpi is advertising their port job worth only that much. Maybe their port job is really cleaning up flashing/ridges and not reshaping? They are charging $300 where renowned porters are getting $450-$550 just for the porting service.

that was 3hp with a stock tb, though, right?

i think adding a big tb will pick up another 10 hp or so. map kpa went down even more after i added the LT2 intake manifold. the only other variable is the rotofab, which i don't think is a restriction.

[RobbyBeefcake87]

Originally Posted by 6spdhyperblue

I used a soler adapter and opened the adapter and the throat to just leave a bit of plastic before reaching the ring

Edit:Rockauto screwed me pretty good. No where to get a gasket local. Going to use the extra time to up the grit on the cartridge rolls and smooth the ports out more. Also wiring the wideband back in for validation.

It took over six hours to port the intake. The runners are nice but are pretty wavy in stock form, also it seems like the throat has more meat on it so it can be opened up more than the LT1 intake. I spent a lot of time opening that up. I was careful not to get it too thin but I’m really happy with how it turned out.

I have a hard time seeing this port job being only worth 3hp. gpi is advertising their port job worth only that much. Maybe theirs is really cleaning up flashing/ridges and not reshaping? They are charging $300 where renowned porters are getting $450-$550 just for the porting service.

I know all the MSD guys are saying that porting the LT2 is a waste of time citing that 3hp gain, but I think you're right and if I remember correctly GPI's port job was mostly a clean up port job.

[cmitchell17]

I got right at .5 psi decrease in restriction at 5650-5700 rpms comparing runs after installing LT2 manifold. I have a 228/236-114 .635/.635 Cam, TSP PRC Heads, 12.25:1, Completely Stock exhaust with cats, ported TB, rotofab. I had a Pray ported intake on for the before comparison:


You can see there is apparently still some restriction the LT2 manifold couldn't take out at higher rpms (>6200)

[s346k]

Originally Posted by cmitchell17

You can see there is apparently still some restriction the LT2 manifold couldn't take out at higher rpms (>6200)

i can't help but wonder how much the stock exhaust is crutching the intake side of things.

[cmitchell17]

Originally Posted by s346k

i can't help but wonder how much the stock exhaust is crutching the intake side of things.

It seems like it would depend on how much GM intended for the exhaust to scavenge (or if they intended it to scavenge at all). They could have just designed it for lower restriction. I realize their number one concern and goal is meeting emissions and especially cat warmup times. I just don't understand why the try-y design? The corvette team didn't do a try-y?

I can tell you I saw absolutely no difference from deleting the primary cats and putting on a primary cat delete pipe. All I found was more obnoxious raspy and loud exhaust.

[s346k]

it seems that the car would suffer above 5k fairly substantially when using stock manifolds with that head/cam combo. what kind of air movement are you seeing? i feel like the stock tb is a restriction on my setup, it has no choice but to do the same on yours.

[Mountain]

Originally Posted by cmitchell17

It seems like it would depend on how much GM intended for the exhaust to scavenge (or if they intended it to scavenge at all). They could have just designed it for lower restriction. I realize their number one concern and goal is meeting emissions and especially cat warmup times. I just don't understand why the try-y design? The corvette team didn't do a try-y?

I can tell you I saw absolutely no difference from deleting the primary cats and putting on a primary cat delete pipe. All I found was more obnoxious raspy and loud exhaust.

I vaguely remember someone at GM talked about this a while back and I can't remember their words.

I could be wrong, but I thought it had something to do with packaging space, cat. light-off/proximity to the exhaust and design of the cats.

The primaries seem nicer in the Camro's tri-y manifolds, but the Corvette's 4-into-1 manifolds seem less restrictive at the collector outlet. It may also be due to the difference's in the vehicle weights and performance goals... Aren't tri-y designs typically well-suited for torque gains in the mid-range and into the higher-RPMs, where separate/equal length is good for augmenting higher RPMs (all relatively speaking)?

I did stumble across this in a quick look:
Corvette (C7)

Exhaust: The Gen 5 LT1 wears a set of cast "four-into-one" short-tube headers, similar in style to those found on the Gen 4 LS7 and LS9 engines but different in both design and build material. Thanks to advanced computer simulation, runner geometry was optimized for minimum restriction and maximum volumetric efficiency. The nearly equal length runners ensure consistent flow from cylinder to cylinder and the "wide mouth" collector promotes a free-flowing system. Unlike the "fabricated" stainless units from the LS7/LS9, the cast pieces were found to be much simpler to produce and lightweight enough for production.

Camaro

Exhaust manifolds: The Camaro LT1 uses a unique tri-Y exhaust manifold design to take advantage of its V-8 firing order. The primary pipe pairings join cylinders one and five, then three and seven on the left bank. Cylinders two and four and six and eight are paired on the right bank. At each bank, the primary pairings collect in a secondary Y, delivering a combination of pulse separation of adjacent firing cylinders and improved scavenging for the LT1 firing order of 1-8-7-2-6-5-4-3. The optimized header and exhaust system improves torque and sound quality.

[cmitchell17]

Originally Posted by Mountain

I vaguely remember someone at GM talked about this a while back and I can't remember their words.

I could be wrong, but I thought it had something to do with packaging space, cat. light-off/proximity to the exhaust and design of the cats.

The primaries seem nicer in the Camro's tri-y manifolds, but the Corvette's 4-into-1 manifolds seem less restrictive at the collector outlet. It may also be due to the difference's in the vehicle weights and performance goals... Aren't tri-y designs typically well-suited for torque gains in the mid-range and into the higher-RPMs, where separate/equal length is good for augmenting higher RPMs (all relatively speaking)?

I did stumble across this in a quick look:
Corvette (C7)


Camaro

Thanks for the info.

So I gather from your above description you posted that the tri-y's were intended to both scavenge each cylinder with its own pulse and also scavenge the out of phase cylinders at a certain RPM. I wish I knew how to calculate all that and figure out what the stock headers target RPM range is.

Of course all this is just a marketing statement that you have to take very very lightly.

I've been trying to get my stock LT1 model on DynoSim6 to peak at the correct RPMs. The peak torque number is right on but HP is only a little above 400, because torque is dropping so much and is peaking to early. Right now its peaking at 4000 rpms, which is where the GEN III truck engines peaked at. The newer stuff and the LT1 peaks at 4400 rpms.

I think I also need to get the correct stock cam timing. I know its 200/207-116.5 .551/.524, but I've heard conflicting information on how far retarded or advanced it sits. I believe it sits in the full advanced (or full retarded?) position and the phaser only can move it one way. I know DynoSim can't model the VVT (it only models V-Tec type VVT with 2 switchable cam profiles), but I know the cam timing from the HP Tuners file so I should be able to advance it to the peak HP and peak torque RPMs and get the stock HP and torque numbers, but for some reason torque is dropping off.