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<blockquote data-quote="brkntrxn" data-source="post: 6579334" data-attributes="member: 12396"><p><strong><span style="color: Yellow">Reviving a thread from the past instead of creating a new one...</span></strong></p><p></p><p>Here we are a year later and I have blown the engine in the 99 Cobra we put together (in a hurry) last year. To give a little background, I had wanted to go naturally aspirated then, but an invitation to a MM&FF drag race drove me to put together another blower motor over a two week period in order to make the event. </p><p></p><p>A couple of weeks ago, I noticed a decent amount of smoke on acceleration (but still very good power). I pulled the plugs and there was oil on #7 and the leakdown showed between 50-80% loss on #7 (depending on the smallest of variances of crank position over several tests). Until the engine is apart, I can only surmise that I have either a broken ring or a broken ringland or something similar. So, I immediately parked the car and I have sold all of the blower related parts and <strong>I will be going naturally aspirated </strong>this time around. No more forced induction $h!t for me. I love the power, but hate the headache.</p><p></p><p>I have a couple of questions for the track gurus. The car will see very little (as in less than a couple thousand) street miles and somewhere around 5-8 open track weekends per year. I am looking for reliability over peak horsepower numbers because seat time is far greater to me than winning the ever elusive HPDE Championship. I'd like to see somewhere around 350rwhp, but I will gladly take OEM driveability over a bragging number. I do not want to go all out as this car will probably never be raced other than Time Trials. Besides, for the next couple of years, my track time improvements will come with more practice and education, not necessarily with more power.</p><p></p><p>My questions for the track gurus are below:</p><p></p><p>1. I have had two sources (an engine builder and Comp themselves) recommend the following cam: 234/232 @ .050 .475/.450 lift with 114 degree lobe separation. This cam will supposedly make power from 1800-6200rpms. Would you choose these new cams over a used set of FR500 set of bump sticks? (I'll not state any prices to protect the innocent) Or stay with my existing Houston Performance custom grind 282 total duration, 470 lift, 114 lobe separation cams and adjust the lobe separation to change the numbers? (I am not overly familiar with how this works, but it was a recommendation by a third source).</p><p></p><p>2. My heads still have the stock springs (~21,500 miles), would you replace them with a new set of 26123-32 springs and 798-32 titanium retainers while the heads were off? (I think I know the answer to this one <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" />)</p><p></p><p>3. 30, 36, or 39lb FRPP injectors? 30s are going pretty cheap right now from Ford</p><p></p><p>4. What compression level? I want to maintain use of 93 octane and keep a safe tune, so is 10:1 about the highest you suggest?</p><p></p><p></p><p>Here are a few quick details on the power parts of the car (99 Cobra): FRPP 2007 aluminum 4.6 block (most likely it will be bored .020 over), Manley rods, ported and polished 99 heads (heads will be gone through yet again), JBA shorties, BBK X, Flowmaster mufflers, BBK TB (installed way before it was discovered TBs do nothing for these cars), C&L Housing with 03 meter MAF, stock intake, return-style fuel system with twin Walbro pumps/Aeromotive pump controller/fuel regulator/Steeda rails, and 3.55 gear. There are a ton more parts on the car, just ask if it will help with the recommendations.</p><p></p><p>Thanks,</p><p></p><p>Kevin</p></blockquote><p></p>
[QUOTE="brkntrxn, post: 6579334, member: 12396"] [B][COLOR="Yellow"]Reviving a thread from the past instead of creating a new one...[/COLOR][/B] Here we are a year later and I have blown the engine in the 99 Cobra we put together (in a hurry) last year. To give a little background, I had wanted to go naturally aspirated then, but an invitation to a MM&FF drag race drove me to put together another blower motor over a two week period in order to make the event. A couple of weeks ago, I noticed a decent amount of smoke on acceleration (but still very good power). I pulled the plugs and there was oil on #7 and the leakdown showed between 50-80% loss on #7 (depending on the smallest of variances of crank position over several tests). Until the engine is apart, I can only surmise that I have either a broken ring or a broken ringland or something similar. So, I immediately parked the car and I have sold all of the blower related parts and [B]I will be going naturally aspirated [/B]this time around. No more forced induction $h!t for me. I love the power, but hate the headache. I have a couple of questions for the track gurus. The car will see very little (as in less than a couple thousand) street miles and somewhere around 5-8 open track weekends per year. I am looking for reliability over peak horsepower numbers because seat time is far greater to me than winning the ever elusive HPDE Championship. I'd like to see somewhere around 350rwhp, but I will gladly take OEM driveability over a bragging number. I do not want to go all out as this car will probably never be raced other than Time Trials. Besides, for the next couple of years, my track time improvements will come with more practice and education, not necessarily with more power. My questions for the track gurus are below: 1. I have had two sources (an engine builder and Comp themselves) recommend the following cam: 234/232 @ .050 .475/.450 lift with 114 degree lobe separation. This cam will supposedly make power from 1800-6200rpms. Would you choose these new cams over a used set of FR500 set of bump sticks? (I'll not state any prices to protect the innocent) Or stay with my existing Houston Performance custom grind 282 total duration, 470 lift, 114 lobe separation cams and adjust the lobe separation to change the numbers? (I am not overly familiar with how this works, but it was a recommendation by a third source). 2. My heads still have the stock springs (~21,500 miles), would you replace them with a new set of 26123-32 springs and 798-32 titanium retainers while the heads were off? (I think I know the answer to this one :)) 3. 30, 36, or 39lb FRPP injectors? 30s are going pretty cheap right now from Ford 4. What compression level? I want to maintain use of 93 octane and keep a safe tune, so is 10:1 about the highest you suggest? Here are a few quick details on the power parts of the car (99 Cobra): FRPP 2007 aluminum 4.6 block (most likely it will be bored .020 over), Manley rods, ported and polished 99 heads (heads will be gone through yet again), JBA shorties, BBK X, Flowmaster mufflers, BBK TB (installed way before it was discovered TBs do nothing for these cars), C&L Housing with 03 meter MAF, stock intake, return-style fuel system with twin Walbro pumps/Aeromotive pump controller/fuel regulator/Steeda rails, and 3.55 gear. There are a ton more parts on the car, just ask if it will help with the recommendations. Thanks, Kevin [/QUOTE]
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