Whose made 700+whp on pump?

[engineermike]

My take is this, most 18+ cars on true pump (no e85, no octane booster, no methanol) will make less than but close to 700. It gets to the point where more boost means more timing retard and buys you no power when you’re dealing with 12/1 compression. Getting rid of cats helps a lot because of reduced pumping losses and more spark timing. Turbocharged cars have an advantage here because they don’t have a blower sapping 100+ hp off the crank.

Don’t get me on my compression ratio soap box because it upsets the coyote-loyal.

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[ugstang17]

Truth!!! 9s is plenty for sure.

and then some huh?.......

 

[80FoxCoupe]

It take is this, most 18+ cars on true pump (no e85, not octane booster, no methanol) will make less than but close to 700. It gets to the point where more boost means more timing retard and buys you no power when you’re dealing with 12/1 compression. Getting rid of cats helps a lot because of reduced pumping losses and more spark timing. Turbocharged cars have an advantage here because they don’t have a blower sapping 100+ hp off the crank.

Don’t get me on my compression ratio soap box because it upsets the coyote-loyal.

What about bleeding off dynamic compression via cam timing?

 

[80FoxCoupe]

and then some huh?.......

While excessive, really cool.

 

[imrex613]

I tried... but my car realy did not like 93 and timing so now im on e85.. lol

 

[ypena02]

Meth injection is awesome. Until the pump fails. Went out twice on my Ford Flex. One time it turned my ecoboost block into Swiss cheese. So I won’t be using meth.

Which brand pump?

 

[sabtaj1]

Which brand pump?

First was a snow pump. Had snow stage 3 kit. Then devils own pump. Not really sure what happened. But had er tuned a lil to hot and was relying on the meth too much. I was an addict. Lmao. 12.01@117 in that brick.

 

[bluebeastsrt]

Better to brag about a time slip than a dyno number. proof is in the signature right above this post. 9.97@138 is something to brag about regardless of what it puts down.

Ahhh man I feel bad now. Best I ever ran on the 93 tune was 10.26@136. Full disclosure. The 9 second run was on e85. But I was one of those hard heads that refused to pull any weight out of the car. So the 9.97 Was good for a really heavy car. Just pooped my dudes thread up a little more with this post.

 

[engineermike]

What about bleeding off dynamic compression via cam timing?

Bleeding off cylinder pressure also means bleeding off torque. And as we know, torque is essential to making power when rpm is limited.

This is an interesting subject, especially since you mentioned dynamic compression. Dynamic compression is typically calculated using the intake valve closing point to calculate V1 in the compression ratio. You reduce dynamic compression by delaying intake valve closing. However, with a PD blower, delaying IVC reduces dynamic compression precisely none. All it does is move when and where the compression takes place (blower vs cylinder). I know it’s a hard concept to grasp at first. But a PD blower moves the same amount of air mass whether the IVC is at BDC or 90 deg ABDC. Therefore, delaying IVC can’t affect the cylinder pressure when it is ultimately governed by the blower.

The only ways to reduce the trapped mass in the cylinder when PD blown with a given blower size and speed are to close the throttle, open the bypass, or increase valve overlap. The latter allows air to bypass the cylinder and, therefore, reduces the trapped mass and cylinder pressure.

Interestingly, even though the GT500 has only 9.5/1 compression, it advances the intake cam and retards the exhaust cam in the midrange, increasing overlap by a full 20 degrees. I can only imagine they are attempting to limit trapped mass and compression in the rpm range where cylinder pressure is the highest, then put it back up top when torque naturally begins to decline. When looked at it in the traditional sense, it would appear to be increasing dynamic compression in the mid-range when it’s actually doing the opposite. I’ve seen similar cam timing in other PD blown engines as well.

 

[sigintel]

@engineermike Excellent explaination on PD w late intake close. I totally never thought about that but duuuhh. Any attempt to flow backwards out cylinder w late close is thus just “compressing” intake manifold charge adding to PD blower compression already (doh, but without intercooling).

On 93 oct pump: 12:1 GEN 3 is more expensive to push above 700 rwhp vs 11:1 GEN 2.

 

[Jackson1320]

Truth!!! 9s is plenty for sure.

Not true. It depends on what you are looking for. I can put a stock coyote in a hacked up fox body and go 9s all day. I would not drive it to pick up my kids. So it really all depends.

 

[Jackson1320]

@engineermike Excellent explaination on PD w late intake close. I totally never thought about that but duuuhh. Any attempt to flow backwards out cylinder w late close is thus just “compressing” intake manifold charge adding to PD blower compression already (doh, but without intercooling).

On 93 oct pump: 12:1 GEN 3 is more expensive to push above 700 rwhp vs 11:1 GEN 2.

How do you figure? The gen3 needs less boost to make the same power as a gen2. Gen3 has less chance of detonation. Gen3 has more knock sensors to cover your ass. So how do you figure? The smallest procharger can put a gen3 over 700whp on 93

 

[Jackson1320]

Bleeding off cylinder pressure also means bleeding off torque. And as we know, torque is essential to making power when rpm is limited.

This is an interesting subject, especially since you mentioned dynamic compression. Dynamic compression is typically calculated using the intake valve closing point to calculate V1 in the compression ratio. You reduce dynamic compression by delaying intake valve closing. However, with a PD blower, delaying IVC reduces dynamic compression precisely none. All it does is move when and where the compression takes place (blower vs cylinder). I know it’s a hard concept to grasp at first. But a PD blower moves the same amount of air mass whether the IVC is at BDC or 90 deg ABDC. Therefore, delaying IVC can’t affect the cylinder pressure when it is ultimately governed by the blower.

The only ways to reduce the trapped mass in the cylinder when PD blown with a given blower size and speed are to close the throttle, open the bypass, or increase valve overlap. The latter allows air to bypass the cylinder and, therefore, reduces the trapped mass and cylinder pressure.

Interestingly, even though the GT500 has only 9.5/1 compression, it advances the intake cam and retards the exhaust cam in the midrange, increasing overlap by a full 20 degrees. I can only imagine they are attempting to limit trapped mass and compression in the rpm range where cylinder pressure is the highest, then put it back up top when torque naturally begins to decline. When looked at it in the traditional sense, it would appear to be increasing dynamic compression in the mid-range when it’s actually doing the opposite. I’ve seen similar cam timing in other PD blown engines as well.

You can lower compression by delaying intake closing because you reduce how much is in the cylinder to compress by pushing it back into the intake. Also the reason for the overlap is for smog purposes,so your engine pushes exhaust back into the intake. This does away with the need for a egr valve. This is one of the first things tuner’s change.

 

[imrex613]

wtf did this thread turn into, lmao

 

[bluebeastsrt]

Not true. It depends on what you are looking for. I can put a stock coyote in a hacked up fox body and go 9s all day. I would not drive it to pick up my kids. So it really all depends.

That's some Nostradamus sh!t right there!

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