Just wondering how many of you are running a ported and/or rod mod stock intake? Wondering if you've had any problems with it and how you've liked it in the long run. I did a lot of searching online but haven't heard of anyone posting about them recently. Looking to put on one my header/cai/tune 2010 GS M6. Thanks!

 

Well, I can't tell you how pleased I am with the rod modded and ported LS3 intake manifold. I can tell you that I'm very pleased with my build, which included a Gwatney ported and rod modded LS3 intake manifold. Everything was done at once. Started with a stock 2013 M6 narrow body. Ported and milled stock LS3 heads, ported and rod modded intake manifold, ported throttle body, U/D crank pulley, Vararam CAI. Kooks 1.875" long tubes, and custom 226/234 115+4 Cam motion cam. It made over 500 to the wheels. With that cam and bolt ons only, it's probably a 460-470 rwhp rig. No telling what increases above that were due to the heads and what were due to the intake manifold. I do know that it would take a whole lot bigger camshaft to reach those numbers with just cam and bolt ons.

 

What did you mill the heads to? Any piston to valve clearance issues?

 

I'm at .620 lift on both sides. Heads were milled .010 and .010 thinner head gaskets were used. I think, with the wider LSA of my cam, PTV clearance isn't an issue. Now, that cam ground on a 110 LSA would probably be problems with the milling and thinner head gaskets.

 

Thanks my cam is fairly similar to yours- i'm installing a 225/236 114 LSA with .629/.615 lift. I'm considering putting on a cometic .04" head gasket to bump the compression. Do you think PTV clearance would be an issue with that setup?

 

Save your old head gasket. Bolt head on and measure clearance. That way you will know how much thinner you can go

 

Is that a Tx Speed shelf grind or something custom? Here's some lite reading for you.. COMP Cams Effect of Changes In Cam Timing and Lobe Separation Angle At first blush, I'd say you'd be fine. But......
The only way to know for sure is to measure like farmington mentioned. I've been considering switching to 1.8 ratio rockers when I change valve springs. I'll check PTV before that move though.

 

Per cam motion you don't want to go more than 6.5* on your IVO BTDC on an LS3 as that already is somewhere between .055-.065 PTV clearance and each 1* IVO represents .006 of PTV. So old motorheads 226/234 115+4 cam for example has 2* IVO which means an additional .027 of PTV (.006 X 4.5 = .027) from the .060 he would have if his cam had a 6.5* IVO. So old motorheads cam would have somewhere around .087 PTV but since he milled the heads .010 and went -.010 on the head gasket his actual PTV is around .067 (plus or minus .005) The general consensus is you want a minimum of .080 PTV but many people do get away with less and pretty much all the big LS3 cams have around .06 PTV for whatever that's worth.

As far as the ported intake read the thread below, a GPI ported & rod modded LS3 intake was worth around 17 ft-lbs of additional midrange torque and some additional throttle response; no hosepower up top.

https://www.corvetteforum.com/forums...no-thread.html

 

Well shoot. That kinda kills the 1.8 ratio rocker arm idea. I am going to check it come valve spring changing time. Just gotta know. I know mine has some crazy torque numbers down low. Gets past 350 ft/lbs at 1500 rpm. The guy that did the initial tune started the dyno run at idle speed. I attributed that to the static compression bump and relatively small intake lobe with 4 degrees of advance. With the milled heads and thinner head gasket, the DCR on my rig comes in around 8.5:1. Low speed manners are so good, I can actually start from a dead stop and shift through the gears without ever touching the accelerator pedal. It pulls down below my 750 rpm idle speed and recovers quickly to idle after every shift. On the 5/6 shift, it won't quite get back to idle speed, but will chug along at about 600 rpm. I think Pat G's street tuning ability has a lot to do with the smoothness down low.

 

I think the Rod Mod helps. I put down 491rwhp on a Dynojet with the BTR Stage 4 cam stock heads, stock intake. Had a lifter eat the cam. So i put in the BTR Stage 3 cam (looking for more mid-range), MAD ported stock heads, MAD ported and Rod Mod intake, put down 512RWHP on a Mustang Dyno.

 

I reread my post and found you an additional .003 of PTV, not enough for 1.8 rockers but moore is always better, made a small mistake and multiplied .006 by 4 instead of 4.5. Also this calculation would be the most applicable to cam motion lobes of course (don't know which ones you have) but I don't think other softer lobes would be far from it either. Here is the thread I read/learned all this in for anyone interested, a lot of good info there.

https://ls1tech.com/forums/generatio...ons-heads.html

 

Good stuff (again). Yes, my cam was ground by Cam Motion. I haven't used Comp Cams stuff since their lovely 918 springs cost me an engine. They offered to sell me new springs at a reduced price. Damn big of them. Haven't used any of their chit since then.

 

Oh yeah, the ported rod modded intake definitely helps IMO. I drove spinmonster commed (47 IVC FYI) C6 GS, same car as mine on the same tires even, not to long ago that put down like 495/440 SAE with just a cam and exhaust on a dynojet so no slouch. The car pulled once it got going but we both noticed right away driving both cars back to back that it felt like it had less torque. It just didn't feel that fast when you punched it in 1st at say 3k. My car, with just the headers & ported/rod modded intake & TB 417/424 rwhp/rwtq SAE, felt quicker off the punch like it had more torque. The tires in mine were fighting for traction and losing that battle while his didn't with no drama at all. We thought and actually talked about the fact it must have less torque at say around 2.5k-3k, it was very noticeable. I later compared both dyno graphs and found that his car didn't have much less if any less torque at that rpm; that's when I realized it was the throttle response which is basically like turbo lag for NA cars and happens when you put a cam in your car (especially one with much later IVC which lowers DCR). Spinmoster always said his cam would feel much better if you picked that DCR back up. His car with a cam that lowers response from stock and my car with mods that pick up throttle response from stock felt way different of the punch. I'm very glad I drove that car because I realized how important throttle response is to the way the car feels, and especially for the way I drive since I like going sideways I have to have that initial punch. The point is dyno numbers don't always tell you how a car will feel so to me a ported TB and intake would be worth it even if those items didn't pick up power at all which they do; the intake mostly but the TB does help with throttle response. Also from reading the camaro forums where Rick Craford is the star of porting intakes, I have his intake BTW, a lot of people report picking up one to three tenths in the quarter just from the intake. My car ran a 12.1 at 118 in 80* temps on street michelins with 2 second 60's with just the exhaust, ported/rod modded intake/TB & tune which I think is pretty decent.

 

I wonder if Spin ever tried adding more ground in advance to his cam. That would probably make it feel snappier down low.

 

Just got my car back. Left the heads alone, but did the RodMod ported intake from GPI and Texas Speed stage 1 cam (225/236 .629/.615 114LSA). Dyno was 487/452. My tuner said the RodMod makes a huge difference, especially in the torque curve. I’m shipping my core back for the $300 refund, which I’m sure GPI is good for based on their reviews.

 

That's pretty good for just a cam & intake. What's the advance on that cam? What Exhaust? Can you post the dyno? How is the throttle response with the new setup?

 

I also have a Airraid Cold Air Intake, Kooks 1 7/8 with catted x pipe, and Borla Type II exhaust. Attached is the dyno results. The lower lines are my old dyno results with just intake and exhaust, the new results are with the cam and GPI Rod Mod Ported Intake Manifold. I believe the cam advance is 114 LSA with 109 ICL.

 

Those are good results for a stg. 1 cam although tsp's stg one is more like a btr's stg. 2. Your before torque numbers seem low, torque should have been much closer to horsepower with headers or did you not have headers? Also, it's hard to believe a cam that closes the intake valve earlier than stock peaks 500rpm later, I don't get why that is. How does the car feel?

 

With a 225 degree intake and 5 degrees of advance, your DCR has to be very high. Seems like it would peak early. Maybe the ported and rod modded intake helps extend that a little.

 

I think the stock ls3 cam closes the intake at 42* as opposed to 41.5 of the tsp stg 1 so we're talking only .5 change which barely affects the dcr; we're talking like 8.233 to 8.268 I also don't think the intake extends the peak, it's not been known to do that plus tsp has a dyno of the cam on their website in which the cam also peaks around 6400. To compare the spinmonster cam closes the intake much later at 47* which explains why it peaks at around 6300rpm