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

beefcake said:

just food for thought

on your original run, peak hp is about 6500 rpms, around 400 rwhp, and and your probably going to shift around 3-400 past that, we'll call it 6900 to be optimal so your coming in on the shift about 360 rwhp

on the new setup, your making peak hp at 7300 rpms, and about 420 rwhp, since the power holds out better, shifting 500 after at 7800 isn't an issue, if you have a 1500 rpm drop on the shift, about 6300 rpms, which will be about 400 rwhp

your use able power is more like 40hp, which in reality is a 10% increase. not to mention the benefit of the higher rpms. which is more efficient too

meaning, you have 3 cars equal weight, equal hp, suspension, etc...

one makes 420 rwhp at 7k, 8k, and 9k.

the 9k car will be the quickest car, then the 8k car, then the 7k car.

i know some get hung up on the down low loss, but in reality, what reason is there to be wot at 3k, etc.. if your trying to maximize et.

now, if you want to go stop light to stop light at half throttle really fast ,vs light throttle, then you will notice it.

but you really going to want to downshift to the power band.

last thing would be, is the tune optimal. cam timing is def huge on these cars!

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Dragster said:

I kept the stock springs. I believe Comp states that you don't need to replace the springs.


I didn't want to mess with cutting the hood or lowering the engine and losing the strut tower brace. Based on the mods the car has, it looks like the cams are the culprit for losing all the power down low, not the manifold. Yes, the CJ would be better with those cams, but hindsight is 20/20... Had it had only a small loss in power, I wound't be so concerned.

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mikeD4V said:

You mentioned that the shop may not be familiar with these cars, is it possible they ran it in 4th gear? 5th is 1:1 in the MT-82. That would show lower numbers and may explain why your data log info seems to be on point. Just a thought. Hope it's all solved on Wednesday.

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gearhead2685 said:

I would blame the tune and intake LONG before the cams is what im getting at. Especially if the down low loss is the complaint here which the GT350 intake manifold is notorious for comp cams in or stock......

To me this looks like a classic case of someome with a GT350 im complaining about the losses down low.

Those cams produce results others have proven that.

Last as beefcake and others mentioned VCT tuning on these cars is huge!! cam tuning can make or break a setup.

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Dynos are a tool. Even if your car reads 500whp on a Dynojet, it will do nothing for your perceived 'seat of the pants' feel.

Are you happy with the change in the powerband of the GT350 IM when you actually drive the car? Does the scream to a higher redline offset the loss near idle? Does it bother you to have to downshift to get into the powerband rather than just putting your foot in it at a higher gear? -that should make your decision, not what a number says on a piece of paper.

If you want to feel better, have them list it in STD because it'll read artificially higher than SAE -which is the standard most people use.

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I would blame the tune and intake LONG before the cams is what im getting at. Especially if the down low loss is the complaint here which the GT350 intake manifold is notorious for comp cams in or stock......

To me this looks like a classic case of someome with a GT350 im complaining about the losses down low.

Those cams produce results others have proven that.

Last as beefcake and others mentioned VCT tuning on these cars is huge!! cam tuning can make or break a setup.

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It's hard to make NA power. It's fricken impossible on the S65 V8 in my old M3. It still blows my mind to see such big NA HP gains for (relatively) little money compared to my M3, which would require extreme builds to even see half of those gains.

I liked the 8,300rpm redline of my M3 and you're basically turning your cammed 350IM Coyote into one -with WAY more power. If you want low-end torque, you should have put all that money into a supercharger (which heat soak like crazy on track), or a Camaro

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Dragster said:

Seems like the GT350 manifold tests I saw showed little to no power loss, and quite a big gain up top, which is why I went with it. These cams definitely produce power, but perhaps they just work better with the Cobra Jet manifold. I certainly never saw a GT350 manifold test where the car lost 40 ft-lbs for nearly 6,000 RPMs.

Yeah, I hear you. I LOVE the idea of having an 8,000 RPM Mustang, so if it comes with power loss down low, then I guess I'll just have to accept it.

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Dragster said:

I kept the stock springs. I believe Comp states that you don't need to replace the springs.


I do have a datalog. I don't know if a wideband was hooked up during the run as I wasn't there (I had to drop off the car); I assume that the only data being checked was what was recorded on the Ngauge. Lund stated that the stock injectors are fine, unless I wanted to run E85.


I suppose that the peak probably won't be that far off what I was expecting. I was hoping for a little over 460 rwhp (Dynojet numbers). Still seems odd to only gain ~20 hp from cams and a manifold, though... Right now my concern is more about the loss of power below 6,000 RPM. I figured it would probably lose 10-20 lb-ft of torque below 4000-4500, but from the graph it looks like it lost ~40 to nearly 5,000.


I didn't want to mess with cutting the hood or lowering the engine and losing the strut tower brace. Based on the mods the car has, it looks like the cams are the culprit for losing all the power down low, not the manifold. Yes, the CJ would be better with those cams, but hindsight is 20/20... Had it had only a small loss in power, I wound't be so concerned.

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Dragster said:

I know, I get it. It's hard for me to say right now because it's been raining here most of the day, so I haven't really had the chance to get on it. The reason I wanted to put it on a Dynojet was because Jon Jr. at Lund thought the numbers were off. He said the data looks solid, but the numbers don't correlate to what he expected.


Seems like the GT350 manifold tests I saw showed little to no power loss, and quite a big gain up top, which is why I went with it. These cams definitely produce power, but perhaps they just work better with the Cobra Jet manifold. I certainly never saw a GT350 manifold test where the car lost 40 ft-lbs for nearly 6,000 RPMs.

Regarding the tune, Lund has a great reputation and has tuned cammed S550s before, which was one reason I went with them. Could the tune be the problem? I suppose so, but I don't know if there's any other cam+350 manifold cars out there to compare it to.


Yeah, I hear you. I LOVE the idea of having an 8,000 RPM Mustang, so if it comes with power loss down low, then I guess I'll just have to accept it.

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Evil 5.0 said:

I see a couple of mentions so I'll chime in, if you don't mind.

I would wait until Wednesday and see what happens on a dynojet so it is more comparable. If the numbers are still low... you may not like it, but my advice would be to sell your IM and throttlebody, someone will scoop it up real quick.

I would go with the CJ manifold with those cams, it is a proven combination. Another thing that will help with that setup is a PMAS CAI. I don't understand why people are so reluctant to trim the hood. It truly is no big deal and if done right it looks stock.

Not all cars react the same to a given combination. I remember back in the day get an intake, B303 cam and some cars would scream on it and others would lack. Don't give up on the cams, the IM is an easier fix.

I hope it works out for you and if you need anything, let me know.

Good luck.

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