Stuck on Manifold choice Sniper vs. 302

MyLilPony said:

lol figure 30/40 for headers and the rest fro manifold. I haven't seen anyone improve in the higher RPM's from headers, gains sure, but not the flat spot.

One thing I thought was interesting was that Z06 lost boost and gained almost all the way up the chart especially up top, even if you split the gains.

The y2 graph was from [MENTION=12006]Deadmau5[/MENTION] maybe he has one with RPM?

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Don't get too hung up on boost numbers. He didn't lose boost, it's just not reading as positive pressure. Dropping boost psi actually indicates gained effieciency. Boost is simply surplus air. If more of that air is consumed there is less pressure back buildup.

At any given rpm the blower is still moving the same amount of air, just a matter of how much gets consumed before the surplus is read as pressure.

BMR Tech said:

I found a solid graph. This is 93 octane on a Procharger.

In this scenario, with the stock manifold, shift points would likely be optimal around 8K RPM, or even higher.

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Not sure I understand this. To me it looks like at about 6800 rpm it stops making any decent gains (not sure about the spike at the end). To me this would be time to shift, probably 7000 by the time it happens.

whatsup62 said:

Not sure I understand this. To me it looks like at about 6800 rpm it stops making any decent gains (not sure about the spike at the end). To me this would be time to shift, probably 7000 by the time it happens.

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The whole shift point idea is keeping it in the best powerband shifting the next gear. Flat power is not the end of the world. Just have to make sure shift point is high enough that the next gear is as close to peak as possible without a major dropoff to have to climb the power peak again in the next gear. That's why say a lund tune n/a shifts at 7,300 on stock mani so the next gear is closer to the 6,500 peak instead of dropping all the way down to like 5,000 much lower on the curve.

Jay-rod427 said:

The whole shift point idea is keeping it in the best powerband shifting the next gear. Flat power is not the end of the world. Just have to make sure shift point is high enough that the next gear is as close to peak as possible without a major dropoff to have to climb the power peak again in the next gear. That's why say a lund tune n/a shifts at 7,300 on stock mani so the next gear is closer to the 6,500 peak instead of dropping all the way down to like 5,000 much lower on the curve.

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Thanks!

I think a discussion on gear shifting strategy as it relates to the vehicle's power band must be had in the context of where and how specifically the driving is going to occur, right?

On a road course, I'd rather keep adding speed to a higher redline than be too concerned about if I make the most power at that given point in time. It'd be nice, but if it is the case that, in order to do so, I'd have to shift a gear too close to the beginning of a braking zone prior to a turn, I'd rather avoid shifting. I may get into trouble with a significantly more powerful car then, but he was already catching up to me at lower RPMS by that point. On a road course, I want midrange personally. Need the car to get its lardy butt moving after a turn and after the tires have their grip. Once I'm hitting the top end of my gearing too much time as passed to care about peak power, IMHO.

On a drag strip, knowing where my power is made would inform when to shift to hopefully get down the track as quickly as possible, but if you have to shift 50 feet before the 1/4 just to capture that best case power, you're losing time. I want my car more than capable of getting off the line quick, but making power all the way up and I'm going to go all the way up so I can switch gears and the RPMs fall within range of peak power for the next gear. And I'm going to hope my gearing and tire sizes are right so I don't bounce off of redline before the finish line. Short shifting, as is my understanding, is shifting before, at a given speed, the RPMs at the next level will not fall close to the peak power of the engine but instead much below it. Not simply shifting early (i.e., before readline).

Of much of that this effectively moot on an auto in auto mode, right? Haha.

whatsup62 said:

Not sure I understand this. To me it looks like at about 6800 rpm it stops making any decent gains (not sure about the spike at the end). To me this would be time to shift, probably 7000 by the time it happens.

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That graph, even before the small spike, is at its peak power. (7300ish)

At 7200-7300 rpm, there is no sign of the power falling.

You do not shift at peak power, you will always have better acceleration shifting past peak hp rpm. So in this case, we can assume that power wouldnt just fall straight down - from that 7300 rpm spot to say 7700 rpm, the power would likely not fall too much at all - so you would likely be better to shift it closer to 8,000 RPM.

As mentioned, a stock manifold in NA form is going to peak around 6600ish....but the fastest cars will be shifting around 7000-7400, in most cases. Even in that configuration, the power is starting to fall off hard....but it still benefits to rev into that power drop range.

If the curve is "flat" - you ride it out until you dont feel safe. If its flat and starts to fall, you will be best shifting significantly past the first signs of power falling.

MyLilPony said:

[MENTION=9648]dubster99[/MENTION] did you lower the motor or just cut the hood? Can you post pictures of where you made cuts if you went that route?

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wildcatgoal said:

I was under the impression you only needed to lower/cut with the CJ, not the Boss? Eh... been wrong before.

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I don't have any pics, but here's one from another forum member's car:



Mine is similar right now, but I'm going to try and clean it up and make it look oem. Another member made a larger cut that follows the weather stripping...looks damn good. I didn't want to lower the motor because my LT's already sit low enough, and didn't want any issues with the paxton charge piping not fitting after lowering the motor.

dubster99 said:

I don't have any pics, but here's one from another forum member's car:


Mine is similar right now, but I'm going to try and clean it up and make it look oem. Another member made a larger cut that follows the weather stripping...looks damn good. I didn't want to lower the motor because my LT's already sit low enough, and didn't want any issues with the paxton charge piping not fitting after lowering the motor.

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I have LT's too and thought lowering the motor would cause issues as well.

Ok so the hitting in only on the back of the hood towards the weather stripping. Good to know, I thought it was the frame of the hood and i had to remove the cover under the hood. So the cutting really isn't that bad.

I am leaning towards Sniper because of the fuel rails. I think the fuel system is going to dictate the route I go. Fore = Sniper | Sai Li = Boss 302...heavily leaning towards Fore since I am an auto and blower car.

MyLilPony said:

I have LT's too and thought lowering the motor would cause issues as well.

Ok so the hitting in only on the back of the hood towards the weather stripping. Good to know, I thought it was the frame of the hood and i had to remove the cover under the hood. So the cutting really isn't that bad.

I am leaning towards Sniper because of the fuel rails. I think the fuel system is going to dictate the route I go. Fore = Sniper | Sai Li = Boss 302...heavily leaning towards Fore since I am an auto and blower car.

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I'm not planning on going fuel system just yet...I'll probably be at my daily driven power goal shortly anyways when I swap pulleys. It's definitely not anything really structural that you need to cut.

MyLilPony said:

lol figure 30/40 for headers and the rest fro manifold. I haven't seen anyone improve in the higher RPM's from headers, gains sure, but not the flat spot.

One thing I thought was interesting was that Z06 lost boost and gained almost all the way up the chart especially up top, even if you split the gains.

The y2 graph was from [MENTION=12006]Deadmau5[/MENTION] maybe he has one with RPM?

Click to expand...

Sadly I don't but I will when I change manifolds

BMR Tech said:

Stock motor, Centri?

Stock manifold is my vote.

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The Boss 302 manifold looks the best and performs great with the centri blowers.. A good clean look when you add the rail covers and blue coil covers. As far as looks go... I think it is the best factory motor look and it put my 13 into the high 10's with a 6 speed.. This is why the aftermarket is so great now. So many options.. I will have to say that BMR has the best suspension parts around!

The flat line is not the end of the world, but a car the doesn't flat line while still maintaining the same low end power/torque and the same shift point of say 7400 should be faster. And the higher the shift point the faster is should go.

My goal here is to eliminate the noticeable flat feel above ~7100. It still pulls, don't get me wrong but not like it does 800rpm earlier.

While I am sure the manifold plays a large part in the leveling the wastage may also as well. I have it set to begin to open at ~10 psi and manage Boost to 12.5. 10psi is reached right about 6000 rpm then it is really Boost management from there. In prior turbo cars Boost was reached a hell of a lot earlier and I ever had this blandness high in the rpm band that I am experiencing now.

We will see..soon!

MyLilPony said:

Here is a before and after of [MENTION=15779]z06psi[/MENTION] when he did his sniper manifold swap. Runs are to 7700 even though the dyno shows otherwise. He lost 1 psi with the manifold but he also added headers.

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No headers. I removed the cats.

MyLilPony said:

My goal here is to eliminate the noticeable flat feel above ~7100. It still pulls, don't get me wrong but not like it does 800rpm earlier.

While I am sure the manifold plays a large part in the leveling the wastage may also as well. I have it set to begin to open at ~10 psi and manage Boost to 12.5. 10psi is reached right about 6000 rpm then it is really Boost management from there. In prior turbo cars Boost was reached a hell of a lot earlier and I ever had this blandness high in the rpm band that I am experiencing now.

We will see..soon!

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Wastegate is definitely part of it. Most wastegated dynos I've seen have a taper up top as well. My old WRX used to actually run less boost at the top, which really felt flat. My car with the boss screams up to 7500...just keeps pulling and pulling.