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Discussion Starter #1
I have a 302 with GT40 (Iron) heads, B cam, Holley 600 DP, Edelbrock Performer RPM Intake, BBK 1 5/8 shorties, X pipe (no cats) and Dynomax Race bullet Mufflers.

I had the Ignition timing set at 10 degrees BTDC at idle. When I dynoed the car it put down 273 RWHP and 294 RWTQ. I am allowed a maximum of 267 RWHP in the series I race in. I ended up retarding the timing to 4 degrees BTDC in order to achieve this. This is not ideal and I would like to lose the power some other way.

My question is this, if I put the timing back to 10 degrees and switch out the intake to an Edelbrock Performer Intake (instead of Performer RPM) will I lose a few HP or will I stay at the same HP/TQ level but in a different RPM range ?

Thanks.
 

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Restrictor plate? Maybe fabricate something adjustable. Probably wouldn't take much. A more restrictive air cleaner might do the trick.
 

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Run some 25W-50 oil in there. ;)
 

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Discussion Starter #7
The heads in that article look like they are 'P' heads too, so with a slightly higher compression ratio should give a little more than mine. For my combo I'm pretty much right where I should be.

The rules don't allow a lot of wiggle room. I can be at 260 RWHP if the car weighs 3,100 LB or I can be at 267 RWHP if the car weighs 3,205 LBS. That's the outer bands, there are different weights/ power numbers for those in between too. My car currently weighs 3,175 LBS.

I have limited options with parts. Carb has to be what I have, cam has to be E or B cam, intake has to be Performer or Performer RPM.

I did dyno the car back in early March on a 45-50 degree day. Now I'm sure the numbers will drop a couple on a 80-90 degree day, however, the beginning and end of season races are on cooler days.
 

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I would bet you will loose more than 8 hp by going the the Performer. I had one on a E303 gt40p engine it didn't like to rev at all.

Can you degree the cam, move the power bad down some to take a few HP out up top?
 

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Why not just add 20lb of weight to the floor, and move up to the next power band class? Putting it on the floor will help lower the COG as well. Middle of the car preferably. Maybe in the boot to keep the front/rear balance closer to 50/50.
 

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I would bet you will loose more than 8 hp by going the the Performer. I had one on a E303 gt40p engine it didn't like to rev at all.

Can you degree the cam, move the power bad down some to take a few HP out up top?
I like the idea of advancing the cam to bring the power band lower which will be more lower end and less on top end.
 

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Don't reinvent the wheel. When NASCAR wants to reduce power, they run a restrictior plate. It's simple and effective. Set the engine up to run right and then restrict the amount of air it can get and adjust your carb to suit the change.

Also, WRC (World Rally Car) runs restrictiors on the rally cars turbo inlets to limit power.
 

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Discussion Starter #16
Thanks for the replies everyone. There are a few options here for me to try.

First, If I advance the cam, won't that yield me the exact same power only in a slightly lower power band ?

Adding weight will not help me, I'm already at the maximum power for the class. If I step up a class then I will have to go aluminum heads, downforce and a bunch of other stuff to be competetive. There are approximately 6 to 7 cars that run in the next class up where in my class now there are around 16 competitors. So I would rather stay in this class where there is more fun.

A Mustang Dyno will not help me. When I finish a race and have to go to impound they will put me on a Dynojet...........

Restrictor plate......... Ok, Nascar uses these and they work, but they are taking out hundreds of HP. I need to lose 8. Nascar teams have Dyno's, wind tunnels, machine shops and countless engineers working for them. I have none of this. What size restrictor plate would I start with ? The idea is good but it's not going to be an easy one.

I like Ed Curtis idea, running heavier weight oil may take at least a couple of HP out. Every two HP I lose is two degrees of timing I can put back.

Throttle stop, that's another interesting idea. I will have to look into that, it may just work.
 

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Discussion Starter #17
OK, so I found a couple of restrictor plates online. Some are adjustable. I guess I should start by measuring the throttle plates on the Carburetor and finding a restrictor plate that is at least the same size and then adjusts smaller from there.
 

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OK, so I found a couple of restrictor plates online. Some are adjustable. I guess I should start by measuring the throttle plates on the Carburetor and finding a restrictor plate that is at least the same size and then adjusts smaller from there.
Correct, regardless you are going back to the dyno one would assume to verify what you changed. A restrictor plate is the simplest common sense approach. Definitely tearing apart the engine is crazy.
 

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I'm sur this goes without saying......but......if you run a heavier oil, make sure you get it up to temp before you hammer down the throttle.

Do they let you dyno before the race to make sure you are within spec?
 
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