My Comp Cams and GT350 manifold results (spoiler alert: it's not good)

Discussion in 'V8 5.0L Engine / Mods: Bolt-ons, Exhaust, Tuning' started by Dragster, Oct 12, 2017.

  1. Dragster

    Dragster Well-Known Member

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    I had a pretty big install project a week or so ago that I had been looking forward to doing: stage 3 Comp cams, a GT350 manifold, oil pump gears, crankshaft sprocket, and ATI balancer. Installation was fairly straightforward, but time consuming. In my opinion, installing cams is actually easier than the oil pump gears, simply because everything is easier to get to. As others have said, the oil pickup tube bolts are a pain to get back in. So if you're doing oil pump gears and you're on the fence about cams, you may as well do them (assuming the additional cost is no problem) since you'll be tearing everything down to get to the oil pump anyway. The hardest part of the install was dealing with two random issues that came up knowing that I had to complete it by a certain time since I had already scheduled the remote tune! In retrospect, I should've scheduled the tune session after I completed the install, but it all worked out.

    My goal for the car was to have a meaningful increase in the rev range, and obviously try to increase as much power on the top end while trying to minimize losses down low and in the midrange. My car is not a daily driver, but it still sees primary on the street. Knowing that I wanted to see the difference the manifold and cams made, I made a baseline run on the same dyno where the car would by remote tuned by Lund. My car is a 2015 GT PP manual, and the baseline run setup was a Lund tune, Roush CAI, Reische thermostat, Kooks 1 3/4" green catted headers and Borla S-type catback. The shop had a Mustang dyno, so the numbers are lower than a Dynojet. Baseline was 401 hp. The shop owner said his dyno reads about 8% lower than a Dynojet, give or take, so that would put the car around 430 to the wheels, which seems similar to what other tune and header cars are making.

    The car went on the dyno for the tune and results yesterday, and the baseline and results are attached. The car picked up power on the top end as expected, but not nearly as much as I had anticipated. The downside, however, was that it lost power everywhere under about 6,000 RMPs. Not only did it lose power, it lost pretty significant power. Likely far more than the power it gained up top. The peak number isn't listed on the picture, but the shop owner told me it was 422. Needless to say, I'm pretty disappointed. I expected to lose a little power, but not that much, and not for 6,000 RPMs. The gain up top was less than I expected as well.

    Jon Jr. did the tune, and he said he doesn't think the before and after pulls are an accurate comparison. He said the data looks good and the MAF is reading 50 lb/min up top. He also mentioned that the manifold alone can pick up 30 hp at 7500 and the cams alone pick up 20-30 rwhp versus stock. I haven't picked up the car or driven it yet (I dropped it off for the tune), so I hope he's right. I like having more RPM to use up top--especially for track days--but the massive loss sucks. Jon Jr. said he thinks these cams work better with a Cobra Jet setup because they lose less down low and carry the power in higher RMP. I didn't really want to have to deal with cutting the hood or lowering the engine though, which is why I went with a GT350 manifold.

    At this point I'm just waiting to pick up the car and see how it feels. I was thinking about putting it on a Dynojet in hopes that it might make me feel better.:lol: I'm not really sure what to do otherwise. I almost wonder if the car would be better off with the stock cams... I can't imagine that the cams added that much to the top end, and I know the GT350 manifold doesn't cause the car to lose almost 45 lb-ft of torque throughout the rev range! It's so disappointing to put in all that work (and money) and see those results... Any thoughts on trying to minimize the power loss? Before and After Dyno.jpg
     
  2. CEHollier

    CEHollier Well-Known Member

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    Man sorry things didn't worked out. I recently did a 350 mani/LU47 swap. Very happy. Feels like more torque down low and pulls harder above 6500. Didn't dyno but do have previous track times. I should be in the high 11's around 118-119 mph. I would have figured you would do better than me with cams.
     
  3. OP
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    Dragster

    Dragster Well-Known Member

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    Thanks man, I appreciate it! I should also mention that the car is tuned for 93 because E85 is virtually impossible to find in my area.

    I'm really wondering if I should just go back to stock cams... From other dyno graphs I've seen, the GT350 manifold is either similar to stock, or just a little lower power wise until 6500 or so, so it would seem that the cams are the source of my power loss.

    :shrug:
     
  4. CEHollier

    CEHollier Well-Known Member

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    Has any members done the same mods? I would think others have. What were their results?
     
  5. Kahboom

    Kahboom Kahboom

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    Stock tb? Stock injectors?
     
  6. OP
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    Dragster

    Dragster Well-Known Member

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    I'm not sure. I'd have to go back and take a look. I thought I saw at least one other member with a GT350 manifold and stage 3 cams, though.

    Yes and yes. I remember people having issues with their Lund tuned 350 throttle bodies, so I kept the stock one and used the adapter. I was okay sacrificing a little peak hp in exchange. Regarding the injectors, Lund only told me I'd need new ones for E85.
     
  7. Braski

    Braski Well-Known Member

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    Hopefully with a revised tune or maybe some supporting mods that were overlooked you can pick up a little more. No mods after a cai/tune really make sense as far as dollar per hp but we always want more!:headbonk:
     
  8. CEHollier

    CEHollier Well-Known Member

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    Have you contacted Comp Cams? They should be able to help.
     
  9. Kahboom

    Kahboom Kahboom

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    Cams love larger throttle bodies, the GT350 throttle body it's hard to dial in you could always get your stock one ported or end up purchasing a larger one down the line. There was an article a while back from mustang360 regarding larger throttle body on the coyote motor and while stock cams didn't really gain anything aftermarket cams gained quite a bit. As far as the injectors go I can let you know that the higher you go up in RPM the stock ones really don't seem to cut it I normally use just 91 or do some mixing of E85 in with it but even just on 91 octane the difference between the lu47 and the stock fuel injectors once you get over 7000 RPM is like night and day. As far as your Dyno goes I wouldn't get too hung up on the numbers until you actually got some track use in to see where your at Now versus where you were previously. Could be something as simple as the person who's doing the die knowing not calibrating correctly when doing it.
     
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    Dragster

    Dragster Well-Known Member

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    That's for sure! It almost reads like a headline from The Onion: "Man spends $2000 and only gains 20 hp." :lol::frusty:

    I have. I'm curious to see what they say. I had previously filled out their online form where they're supposed to contact you and let you know which cams are best for your specific application, but nobody ever contacted me back. I had to speak with someone in tech support though during the install process, and they were great and very knowledgeable.

    Kahboom--that's good info on the throttle body, thanks! I'll keep that in mind. I'm trying to keep an open mind considering I haven't even driven the car yet, but that dyno graph... :lol: That's one reason why I was considering seeing what it looks like on a different dyno. Even Jon Jr. at Lund thought the before and after weren't a good comparison. The thing is though, it's the same dyno for before and after, so unless they changed calibration or did the runs in 4th gear, I can't really see how it couldn't be correct.
     
  11. CEHollier

    CEHollier Well-Known Member

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    Please keep us posted. Very curious what is up?
     
  12. Kahboom

    Kahboom Kahboom

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  13. Taneras

    Taneras Well-Known Member

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    While I can't explain the loss in the low to mid range, and while I'd still expect larger peak gains between the comparisons, your 422rwhp peak output on a mustang dyno would translate to a ~460rwhp peak output on a dynojet.

    Compare that to this guy's setup:

    [ame]

    He's 453rwhp, no stage 3 cams sure but he's also running catless and E85. Just doing napkin math catless = 5rwhp and E85 = 15rwhp. Those extra advantages add up to around ~20rwhp, and he's still 7rwhp behind you. If the cams are suppose to add 20-30rwhp, and you're ~7rwhp ahead of someone running E85 and is catless it seems you got the power.

    Sure, sure, different machine, different car, different weather, but all things considered the two setups do match pretty well.

    I'm not saying something isn't wrong, but comparing your peak to his peak, and considering the mods, that does seem to line up about right.

    One possibility that could account for the seemingly small increase in power with your before and after dynos is the weather. If they started in the morning, in cooler weather, did a baseline, spend the better part of the day installing the new parts, then did the results dyno at the end of the day when the temperature was a fair bit warmer that would throw off the results. You'd be giving the baseline an advantage (cooler temperatures) and the results dyno a disadvantage (warmer temperatures).

    Your baseline does seem a little high imo, 430rwhp (rough dynojet numbers) is *VERY* respectable for a 93 tune, CAI, and catted LT's imo. Not saying that people don't get those numbers, because they do just as you did, just that that's probably on the upper end of the spectrum which suggests optimal air. If your results dyno didn't have similar air its really tough to draw much of a conclusion.

    Personally I wouldn't sweat it until you drove it. You mentioned track days, do you mean drag racing? If so hopefully you have a couple of runs done prior so you can compare. I was sort of in the same boat, I didn't notice anything at all after I installed my SP catless headers. My trap speeds at the track clearly showed that I got great gains from that mod, despite my butt dyno saying there was no difference.
     
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  14. racered_ppGT

    racered_ppGT Well-Known Member

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    i made 430whp and 398wtq with just a lund 93 tune, catless longtubes and a cai on a dynojet, but i agree that my car does not feel like a 430whp car, i might just be used to it though, which is why my next mod will be FI :)
     
  15. jcart953

    jcart953 Well-Known Member

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    ^Do you have a dyno sheet lol I love to see it. You can PM me if you want.
     
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