Hey guys.

Not the typical "Help me spec a cam" thread that you're used to.

I'm looking for those experienced with AI lobes and how they differ from the EPS lobes.

The two cam options on the table thus far for my 06 6.0 GTO are:

AI Lobes .230 .238 .605 .605 113+2 LSA on a 111 ICL

EPS Lobes .230 .238 .600 .615 113+2 LSA on a 111 ICL

I understand they are both very close to each other in duration and lift but really wanted to focus my question to the differences in the characteristics of each lobe profile and which would be ultimately right for me.

If anyone is experienced with BOTH lobe designs, I would greatly appreciate some input. Looking to pull the trigger on a H/C/I package this week and it comes down to choosing between the two cams above. Durability is key as this will be daily driven to and from work as well as on the prowl on the weekends with very limited track time. No other cam suggestions are needed as I have already decided either of these cams are my only two options. I'm trying to optimize the power output of this setup. Basically I'm trying to get as close to having my cake AND eating it too.

Setup as shown below:

CNC'd 232cc GM LS6/LS2 243 Casting Cylinder Heads milled to 63cc for 11.3:1 compression
BTR .660" Polished Dual Spring Kit w/ locators, viton seals, & Titanium Retainers
Ai 4130 One Piece ChromeMoly Hardened Pushrods 5/16" & .080" Wall Thickness
Home Ported FAST 102mm Intake Manifold
Nick Williams DBW 102mm Throttle Body
Powerbond 25% Underdrive Pulley
Kooks Stepped 1 3/4 - 1 7/8 Headers
Kooks Off Road Non Catted Mids
Magnaflow 2.5" Axle Back Exhaust
DMH Low Profile Cutouts Installed In Mids

Looking for a strong/early torque curve with around 400est. rwtq at 3k and pull smoothly to around 470 rwhp peaking around 6500rpm - 6600rpm. Optimal torque output would be around 440 rwtq (obviously a bit earlier than 6500-6600)

I understand this doesn't have any bearing on the original question but I wanted to throw my soon-to-be setup out there for background going forward with this discussion.

Thanks in advance for any knowledge imparted.

 

I have the EPS cam you posted in my car. It is going to peak earlier than you are thinking unless the CNC porting of your heads changes things more than I expect it would.

In my combo it peaked at 6200rpm then started a nice slow carry down. Made 390rwhp unlocked converter through the mufflers. I expect had I locked it up and uncapped the mufflers it would have made at least 415rwhp through the automatic.

My heads have some mild hand porting on the intake side, nothing but sand rolls ran through the exhaust. Shaved .010" so likely around 10.7:1 or slightly higher compression.

Drivetrain is quiet and I have probably passed the 20k mile mark on some Patriot Gold dual springs with no signs of float. I would definitely recommend it, but I do not have experience with the AI lobes

 

As far as I know, AI doesn't have their own lobes. You choose your lobes or they can choose them for you depending on the usage of the motor. As far as we know, the cam you posted from AI can have an LSL lobe on the intake and an XER on the exhaust.

EPS lobes which are lobes proprietary to Geoff Skinner@ EPS since he designed them himself. Him and PatG are the only ones that I know of are authorized to use them. His lobes are designed for the best of both worlds of longevity and power.

 

87silverbullet -

According to AI, "their lobes are less aggressive than LSL as well as EPS lobes".

I wonder if they use a HUC lobe?

I know Geoff and Pat are the ones who mainly deal in EPS lobes. Did I mention that I was going to have AI grind their lobes or something? If so, it came out wrong. I was more referring to the cam specs/lobe profile I will be going with. Regardless of who I get the heads from, the cam will be either coming from AI or Geoff/PatG and sent to AI for cam doctoring to prove accuracy while I wait for my heads to be completed and shipped to me.

thunderstruck507 -

I'm cool with it peaking there. I would prefer it to peak a little later optimally but we'll see how it does with those heads and everything. I should say I intend to SHIFT around 6600. I know that changes the game a bit. Sorry for the mistype. I'm wondering if I can hit the numbers I'm looking for and throw around about a 123-124 trap if I can get her moving quick enough.

 

mine is EPS lobe intake and LSL (or is it LXL?) exhaust...he said the exhaust lobe was softer to keep noise down

don't have a good video but here is what I've got, was idled high during and the camera doesn't pick up sound very well due to dumped exhaust:

 

I'm *thinking* that is an LXL on the exhaust. LSL is generally used on the intake side of things unless FI if I'm not mistaken. Of course, that's what GENERALLY happens, not always. LXL is also soft of the close for a quieter valvetrain.

Edit: LXL

290 238 159 .362 .094 .079 .579 .615 .652

 

Yup that changes the game, 6750rpm is as high as I've taken mine for shifts I started at 6400 and got that far. It went faster all the way to that point. Depending on how your RPMs fall between shifts you might not even have to take it that high for peak results which would also help you with engine longevity.

AI heads I'm sure would put my home worked junk to shame. With the better heads, better headers, better intake manifold, manual trans, and likely a better intake ducting setup I think you will be very pleased with the performance.

 

Bump up. Anyone else with experience with these lobes?

 

I'm running AI's mild lobes with the specs below with PSI 1511 long life springs and fresh stock lifters. Only about 3k miles so far with a 6800 rev limiter, but it's about a quiet as stock. I told Phil I didn't want to have to check spring pressure every 25k miles and that I wanted daily driver reliability. He said they'd go 40-50k miles before I'd even consider checking checking the pressure and that these lobes don't come close to needing a dual spring. He told me with my setup it should be stable up to ~7500. They are a mild lobe, a lot more than most Comp lobes as well as EPS lobes. If anything lets go on my setup, it'd be the bottom end.

I'm guessing these are his proprietary lobes as he uses several different cam mfg's depending on lead times; Comp Cams is NOT one of them due to quality control issues he and others have had. Cam Motion and Bullet are probably the most commonly used, and my cam spec'd out within 0.1-0.2 of a degree of advertised specs.

Jason

 

I'm running AI 226cc 243's, stock Fast 102, 347ci, and an AI "mild lobe" cam. 236/242 .630/.630. I've been shifting at 6800 and the engine easily pulls past 7k although there's no point in doing so. I do have ARP rod bolts and forged CP Bullet pistons.

Race weight 3450, so far best pass 11.26@122.3, 1.56 60' with the T56 and stiff wall slicks. I expected more mph out of this combo, and I may get it eventually. I'm doing the tuning myself and am running OLSD.

I've enjoyed the tuning/driving process a lot, and have whittled it down from 11.83 my first day out to 11.20's.

 

I have AI 226 heads with EPS 230/238 cam, portted fast 92, 1"7/8 kooks, Kooks daul exhaust and made 435 rwhp through a auto.