it was.

http://videos.streetfire.net/player.aspx?fileid=2AEE2F41-5D59-48D1-9624-03CA7C2648FC

Big HCI 02 SS vs big cam 6.0 LS1 88 IROC http://media.putfile.com/02-SS-vs-88-Iroc

03 Cobra with small mods vs 02 GT with 100 shot
http://media.putfile.com/03-Cobra-vs-02-GT


97 Cobra vs 03 350Z, short race
http://media.putfile.com/97-Cobra-vs-350Z


97 Cobra vs 94 Z28
http://media.putfile.com/97-Cobra-vs-94-Z28

Here is the 02 SS vs the 02 Lightning. The Lightning has a Forged Bottom End, Patriot Heads, Comp Cams, Whipple @ 19 PSI, 2600 stall. Was a good race!

http://media.putfile.com/John-vs-Casey

Some earlier races of the 02 SS and the 88 IROC, SS didnt wanna go in fourth the first run, IROC was sleeping the second run.

http://media.putfile.com/John-vs-TJ

The SS MOVES in fourth, ~~~~! That IROC has run 97 MPH in the 1/8 and is no slouch! We had 2 people in the IROC though but Im light riding in the IROC.
__________________
 
Heat and restriction all come into play, but I'm surprised the fact that efficiency of the blower itself hasn't been mentioned. Any type of artificial aspiration has its efficiency limit before you just aren't adding any more power. The OEM does a good job of sizing turbos/superchargers for the application at hand, not so much above and beyond. We can get away with a tweak here and there but nothing huge. A given supercharger of a given displacement can only flow a certain max cfm rate. Now when you start changing blower sizes even in positive displacement I DEFINATLY see a change in the curve from one blower to the other.

EX:
03 Cobra’s/Lightning Eaton to Whipple
I’m seeing a LOT more top end with the Whipple then with the Eaton.

Changing 671’s to 871’s we are seeing not only torque increases but top end increases as well (depending on blower RPM). Any form of artificial aspiration can only flow so much air efficiently before you get “pumping losses”.

I have also seen something similar to this with Nitrous Oxide. We get to the point where we simply just can’t cram any more in and out of the cylinder and the vehicle starts to loose power even though we are putting more into it.
 
CarlisleLandOwn said:
I have also seen something similar to this with Nitrous Oxide. We get to the point where we simply just can’t cram any more in and out of the cylinder and the vehicle starts to loose power even though we are putting more into it.

yep..have also run into this problem..but not really losing power. My buddys car (the ones i posted the vids of) runs a dry kit, and was going consistent 10.30's with a .098 jet. We eventually went to a .102, didnt pick up anything at all.. started drilling that jet until we had it at about .110 and it still would not pick up anything.
 
Car Craft did a test one time where they took a basic small block motor and put increasing amounts of nitrous on it till it blew. They got to about 250hp when they apparently ran into that problem. The nitrous started backing up in the intake and it blew up the carburator or something. They decided that they had reached the limit with that combination of what the motor could ingest.

Blower efficiency it certainly an issue and it has two fronts from where I see it.

1) at a certain rpm the VE of the blower starts to fall off badly. This would be due (I assume) to air velocities in the ports and around the rotors.

2) power consumption due to a non-linear increase in drag as rpm increases.

I've seen graphs for some of the blowers but none of them extend into the rpm ranges that we are taking these things. Funny how the manufacturer's charts all stop several thousand rpm lower than what we are running them.

Maybe it is more about blower efficiency than IC efficiency. I made the connection because I've logged the air temps of many SC motors and I've seen a direct correlation between temps and power output. People who spin their blowers very fast will also show steep increases in temp above (in our cases) 4500rpm which also matches the power fall off of most SC motors.

However, I am also willing to accept that my observations may be more the reflection of two paralell conditions and not so much cause and effect. For us the way to find out is to run the biggest blower we can find vs. the same blower in a smaller displacement at the same boost levels. I will be doing this but not tomorrow or next day. It will take a little time to put the puzzle pieces together.

We are lucky in this regard because we have the option of running a much bigger blower compared to displacement than the "other guys" can. I can put a 2.6L on an SC motor and compare the results to that of the 1.7L. We'll have to see what happens.
 
XR7 Dave said:
Car Craft did a test one time where they took a basic small block motor and put increasing amounts of nitrous on it till it blew. They got to about 250hp when they apparently ran into that problem. The nitrous started backing up in the intake and it blew up the carburator or something. They decided that they had reached the limit with that combination of what the motor could ingest..


call up NOS/holley and ask what the maximum nitrous amount to use on your motor is. 10-1 they give you the same answer they told me


"keep jetting it til it blows up, then back it off 50hp" :rolleyes: :D
 
Blown 91 Bird said:
yep..have also run into this problem..but not really losing power. My buddys car (the ones i posted the vids of) runs a dry kit, and was going consistent 10.30's with a .098 jet. We eventually went to a .102, didnt pick up anything at all.. started drilling that jet until we had it at about .110 and it still would not pick up anything.


There is a reason for this. You can only get soo much fuel from bumping your fuel pressure. Afterthat you won't supply enough for proper combustion and it will no longer increase hp.

XR7 Dave said:
Car Craft did a test one time where they took a basic small block motor and put increasing amounts of nitrous on it till it blew. They got to about 250hp when they apparently ran into that problem. The nitrous started backing up in the intake and it blew up the carburator or something. They decided that they had reached the limit with that combination of what the motor could ingest.

Blower efficiency it certainly an issue and it has two fronts from where I see it.

1) at a certain rpm the VE of the blower starts to fall off badly. This would be due (I assume) to air velocities in the ports and around the rotors.

2) power consumption due to a non-linear increase in drag as rpm increases.

I've seen graphs for some of the blowers but none of them extend into the rpm ranges that we are taking these things. Funny how the manufacturer's charts all stop several thousand rpm lower than what we are running them.

Maybe it is more about blower efficiency than IC efficiency. I made the connection because I've logged the air temps of many SC motors and I've seen a direct correlation between temps and power output. People who spin their blowers very fast will also show steep increases in temp above (in our cases) 4500rpm which also matches the power fall off of most SC motors.

However, I am also willing to accept that my observations may be more the reflection of two paralell conditions and not so much cause and effect. For us the way to find out is to run the biggest blower we can find vs. the same blower in a smaller displacement at the same boost levels. I will be doing this but not tomorrow or next day. It will take a little time to put the puzzle pieces together.

We are lucky in this regard because we have the option of running a much bigger blower compared to displacement than the "other guys" can. I can put a 2.6L on an SC motor and compare the results to that of the 1.7L. We'll have to see what happens.


Dave, all of the above are conditions that will lead to power loss. As you know it’s a balancing act and Ford never intended for these motors to make as much power as we are building them to. If you don't solve ALL the issues at hand it will still never be correct and the desired result will never come forward.
 
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