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Unit 5302 · 02-06-2007, 08:21 PM

First off, this topic belongs in the Modular Madness forum; however, I will answer some of your questions below.

1) No. The parts you're adding to your engine will REDUCE the amount of horsepower you're going to make because they will be heavier than the parts they replace. Your engine will be stronger than it used to be, but with the same displacement, same air/fuel delivery and exhaust,t he extra weight will cause you a parasitic loss in total performance.

2) You should focus on power adders (forced induction) with your engine rather than keeping it naturally aspirated, IMHO. If you're set on keeping the engine NA, camshafts are a big boon to your setup.

3) The cost and performance gain of porting/polishing your cylinder heads are likely proportional to one another. The better or more aggressive the port/polish job is, the more time and experience will likely be involved so you'll pay more. A basic port job may run you just a few hundred dollars while an aggressive professional porting and polishing job will run well upwards of $1,200. With your engine, you might expect to see as few as 20hp for a few hundred, and as much as 50hp+ by aggressive porting IF depending on whether you add additional parts. When you're adding NA horsepower, you often have to look at replacing multiple parts, and you often lose drivability on a small displacement engine like your Cobra's 281ci (4.6L) V-8.

4) This again, would depend on how much power you're adding.

02-06-2007, 08:21 PM	#2
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	Re: 1998 Mustang Cobra Engine Work Question? First off, this topic belongs in the Modular Madness forum; however, I will answer some of your questions below. 1) No. The parts you're adding to your engine will REDUCE the amount of horsepower you're going to make because they will be heavier than the parts they replace. Your engine will be stronger than it used to be, but with the same displacement, same air/fuel delivery and exhaust,t he extra weight will cause you a parasitic loss in total performance. 2) You should focus on power adders (forced induction) with your engine rather than keeping it naturally aspirated, IMHO. If you're set on keeping the engine NA, camshafts are a big boon to your setup. 3) The cost and performance gain of porting/polishing your cylinder heads are likely proportional to one another. The better or more aggressive the port/polish job is, the more time and experience will likely be involved so you'll pay more. A basic port job may run you just a few hundred dollars while an aggressive professional porting and polishing job will run well upwards of $1,200. With your engine, you might expect to see as few as 20hp for a few hundred, and as much as 50hp+ by aggressive porting IF depending on whether you add additional parts. When you're adding NA horsepower, you often have to look at replacing multiple parts, and you often lose drivability on a small displacement engine like your Cobra's 281ci (4.6L) V-8. 4) This again, would depend on how much power you're adding.