Short version: I have a mildly built 370 ci turbocharged engine in a 2003 Mustang with a manual transmission, and want to improve drivability and fuel economy with a milder cam. I'm looking for recommendations as to what I can try. I was thinking of trying an OE LS9 cam and switching to a Gen 4 timing cover.

Details:

Build specs:
370 ci Gen III engine based on LQ4/9 truck block, stock 3.6" stroke
Misc. internal upgrades, forged pistons/rods, ARP main and head studs, LS9 head gaskets
~9.5:1 static CR
PRC 225 cc as-cast cathedral port cylinder heads with .660" capable valve springs
LS6 intake manifold
Gen III truck engine controls (2-bar SD, DBW)
ID720 fuel injectors
Turbonetics T-series 7875, .96 A/R T4
Custom turbo kit using LS3 Camaro exhaust manifolds

Current cam specs:
Texas Speed 228/232 (@ .050"), 114 LSA, .600" peak lift, +3 advance

The engine makes plenty of power. I managed a best of 747 whp at 6000 RPM and 13 psi of boost last time I had it on some Dynapacks (on pump gas), and it seemed to have more left in it. However, I am using this engine with a manual transmission and want a smoother idle, less lope, smoother low-load and low-RPM drivability. It's not bad, per se, but even after spending a good bit of time tuning it, it still bucks a little below 1500 RPM, and it only pulls about 13 inHg of vacuum at a 900 RPM hot idle. I also get lousy around-town fuel economy even though the AFR is dialed in pretty well.

I want to try something that is easier to tune for daily driver duty and doesn't attract as much attention. I realize that I'm going to sacrifice some power by doing so, which is fine because 750 whp is more than I really need anyway. What are some good "compromise" options? I was thinking of switching to something like a stock LS9 cam, since it was used in production forced-induction applications, presumably on an LS3-style cylinder head (which appears to flow similarly to these PRC cathedral ports).

 

Get in touch with John at LJMS and have him spec you one.

 

I'll certainly consider that if there are no off-the-shelf combos worthy of trying.

 

LS9 would idle like glass but likely have less power than you have now below 4k and be a poor choice for a manual trans street car.

If you want something with pep look at the small ISKY truck grinds JFR sells. (Or similar.) 215/215 @ 112 .565 lift is a great street cam. The 212/212@ 112 (triple 12) would really wake up the bottom end. If you are not planning on revving it over 6k and you want quick spool I’d go that route. I ran some 8 sec passes on that “baby” cam and it drove and sounded like an OEM cam IMO.

 

Isky cams from JFR would be my go-to for torque. Even one of the larger ones he has like the 218/218, 218/224, or 224/224 would be excellent.

I'm using a Howard's 222/222 113+4 LSA in a friend's 5.3. Manual trans, stock 5.3, tiny china 50mm twins, 3600 lb race weight and it runs 10s.
Basically any cam with durations in the lower 220s, with an LSA no lower than a 112 and .550+ lift is going to work great. Lots of choose from.

 

I like the Elgin E-1839-P, can be had for $250-260 on amazon/ebay. Its a 220/224, .575/.575 112+4

 

Thats probably my favorite of the Elgin cams. Very stable valvetrain with that one, but only because the lobes are so lazy that the rest of the valvetrain just kind of takes a nap.
Its one of the mildest intake lobes I've seen for an LS. Its more mild than EVERY shelf cam offered by BTR, Howards, Comp, etc. Lunati and Crane each only have a single cam with a lobe more mild that that one.

And the smaller 216/220 Elgin cam has an intake lobe EVEN more mild than it does. I imagine its because the cams aren't made out of the strongest material so it prevents wear.

 

With that size engine and cam, you shouldnt be having problems with surging. Good tuning will resolve your issues. You need to mess with injection timing. That will make a good bit of difference.

 

That being said, you have alot of back pressure with that engine/turbo combo. You are going to want some negative overlap

 

Tu1 all day, -16-18 inches of vacuum at 800ish idle. It's a tried and true cam that makes good power with a smooth idle.

 

The 2002+ z06 cam that used to be the super cheap cam upgrade for mild builds is no longer the super cheap option, but it still checks all of the boxes for what you want. It will idle smooth as glass in a 370, has no overlap to consider for excess backpressure, and many people have greatly exceeded your HP requirements with it. We put one in my neighbor's lq9 Escalade years ago with a 67mm Garrett, and the combo is still going several transmissions (and 15 years) later.

 

A man. trans always is a comp. bet. drivability and top end power, been there over the years, lol.
Prob. one of the cams as suggested would fit the bill. Back in my gen one days, we would sometimes
run the Rhodes lifters, they would bleed down at idle/low RPM's. They had to be adjusted properly,
and were noisy (to some people, I always liked solid lifter sound).
I noticed they make them for LS engines, you would need to swap PR lengths for proper adjustment.
Prob. your best choice is just cam replacement.

 

I've played around with injector timing a bit, as well as timing advance at low load. I've got it cleaned up about as far as I think I can. It's not that the car has bad surging or anything like that--I've driven much worse. However, it'll never be a very nice thing to drive in a traffic jam. Since this car is intended as a very silly daily driver and I have no ambitions of drag racing it (heck, I'm using a manual transmission, a Torsen diff, and 275-width street tires, not exactly an effective combo for hard launches), I am willing to give up a bit of power in exchange for a stronger, smoother idle and a little more low-end torque. It'd be nice to get more than 13 mpg, too.

I filled out LJMS' spec sheet; we'll see what they recommend. I'll probably go with one of the off-the-shelf options proposed above if their recommendations are fairly close--no point in getting a custom grind if we're just going to recreate an LS6 profile or something like that.

 

The cam you have is in no way aggressive...so what exactly are the problems you are having ?

Sounds like you're wanting to change the cam to fix bad tuning....which clearly it will not do. It should already have a pretty smooth idle

If you really want silky smooth, consider some of LPE's cams, although yes the LS9 would give you that too. Some of LPE's are very mild, wide LSA albeit with a lot of lift. So will be silky smooth, but achieve/allow good airflow via that lift profile instead of being aggressive in other ways. Of course you need springs etc to suit.

 

kinda similar combo to my old set up. except mine was/is bargain basement junk

running a copy of the TSP stage 3 high lift truck cam on a 114

beware though, literally no chop. in a manual trans I might try the 112

 

For 370ci and that small of a cam.... you need to find a better tuner to get rid of the surging. 750rwhp will get old after a while.... trust me

 

It's mostly that I'm just really picky. Drivability is actually pretty good for the most part, and has gotten better over the last few months as I've continued to mess with it.

Idles at about 13"-14" of vacuum at 900 RPM. It is a reasonably smooth idle, but still more lope than I'd prefer. Mild surging below 1500 RPM at low load (lift throttle coast). It used to be a lot worse, but I played around with the end-of-injection timing a bit so it doesn't short circuit fuel as badly; unless my math is wrong, it should end injection just as the intake valve passes .050" lift. Later than that doesn't seem to help, and it definitely does not like earlier (tends to surge more). I'll have to check what I'm using for ignition timing, but I found that it seems to like quite a bit of timing advance at low load. There is a slight tendency to surge at part throttle (low load, forget how much vacuum) at 1600-1700 RPM that I haven't quite figured out yet. I've got fairly smooth transitions through that RPM/load range in both the VE (the car is tuned speed-density) and timing advance tables, so it could just be some DBW/throttle follower shenanigans I haven't figured out yet. Need to play with it a bit more.

Although I realize this is nothing compared to some of the huge NA cams folks are running for higher-RPM applications, I'm just not a huge fan of lopey idle and want to trade off some power for low-RPM torque. Maybe even something vaguely smog-friendly.

 

Your problem is tuning, not the cam

 

The few remaining, minor part-throttle issues can probably be mitigated with further tuning tweaks; the stuff I've done over the past few months has been a major improvement. However, all of that won't miracle this thing into not sounding lopey at idle, or having as much low-end torque as a stock cam. It's a question of priorities in a daily driver.

 

That cam is small, it should not be loping at idle.