PB GT/CS
Active member
Folks, I was doing some catch up on the site today. I noticed on the "Member of the Month" section a discussion on Intake Manifolds for a 428CJ started by Don and GT asked the questions about performance issues. I am a long way from being an engine builder expert but I went through this decision process when I built the 428CJ for my Cobra S/C. The bottom line in Intake Manifolds seems to be a question of RPM range the engine is expected to do most of its work and a match to other parts of the engine. This is 4 year old info and my memory may be a little off, but here is how I remember it.
Edelbrock makes several performance intake manifolds. The Alum RPM manifold which is made pretty much to mirror the performance of the intake on the Police Interceptor of the early FE engines. They are designed to work well for engines turning 1500 to say 4000 rpm. The next level up in Performance is the RPM Performer. That makes more HP in the 2500 to say 5500 rpm range. The Victors are the big dogs and are made to make HP in the 3500 to north of 6000 rpm range. My buddy who built at the same time used the Victor Jr since he was interested in running Autocross and such. He geared his car so it would run nearly 6000 rpm on the course and hold HP there. He "chipped" his engine at 7000 rpm max. I chipped mine at 6K.
I bought for my 428 the Edlebrock RPM Performer kit minus Carb. That was Cam, Alum heads, and Intake all matched to make HP in the 2500 to 5500 range. I used a Holly 750 DP as a carb as it was "more original". Almost all of my usage on the car is for street driving with a little heavy foot sometimes. The engine showed exactly what Edlebrock advertised when it was on the dyno. Was a dog up until 2500 and really came to life until it got to 5500 and tailed off after that. From the back of the engine, 460 hp, 525 Torque :grin:
My friend made a lot of HP in the upper range (over 500), but it takes a lot of RPMs to get the correct fuel mixture down those long runners on the Victors.
I am sure others on this site have more engine builder experience than I do. However, this was my observation when I had my engine built. So, the bottom line is decide where you want the engine to be strongest. If it is a street machine only, do you really want an intake that does not begin to really come on until it sees 3500 to 4000 rpm?? If so, probably better look at the cam specs to see how that matches that range. If you have the heads ported polished and big valves, you are on the correct path to handle the additional air flow the Intake will move. Do you have enough cam to hold those big valves open long enough to handle the air flow??
Finally, we gained the most HP on the Dyno by adjusting the curve on the Distributor and jetting the carb. We started out at 390 HP and got to over 450 by making those adjustments. As most engine builders will tell you, all of the parts need to work together. These performance parts make engines move a lot of air and can be tricky on the timing. Everything needs to work together.
Hope this helps and if you have any questions, I will relay the information I can remember or perhaps someone with more knowledge can also come to my rescue if they disagree.
Brian
Edelbrock makes several performance intake manifolds. The Alum RPM manifold which is made pretty much to mirror the performance of the intake on the Police Interceptor of the early FE engines. They are designed to work well for engines turning 1500 to say 4000 rpm. The next level up in Performance is the RPM Performer. That makes more HP in the 2500 to say 5500 rpm range. The Victors are the big dogs and are made to make HP in the 3500 to north of 6000 rpm range. My buddy who built at the same time used the Victor Jr since he was interested in running Autocross and such. He geared his car so it would run nearly 6000 rpm on the course and hold HP there. He "chipped" his engine at 7000 rpm max. I chipped mine at 6K.
I bought for my 428 the Edlebrock RPM Performer kit minus Carb. That was Cam, Alum heads, and Intake all matched to make HP in the 2500 to 5500 range. I used a Holly 750 DP as a carb as it was "more original". Almost all of my usage on the car is for street driving with a little heavy foot sometimes. The engine showed exactly what Edlebrock advertised when it was on the dyno. Was a dog up until 2500 and really came to life until it got to 5500 and tailed off after that. From the back of the engine, 460 hp, 525 Torque :grin:
My friend made a lot of HP in the upper range (over 500), but it takes a lot of RPMs to get the correct fuel mixture down those long runners on the Victors.
I am sure others on this site have more engine builder experience than I do. However, this was my observation when I had my engine built. So, the bottom line is decide where you want the engine to be strongest. If it is a street machine only, do you really want an intake that does not begin to really come on until it sees 3500 to 4000 rpm?? If so, probably better look at the cam specs to see how that matches that range. If you have the heads ported polished and big valves, you are on the correct path to handle the additional air flow the Intake will move. Do you have enough cam to hold those big valves open long enough to handle the air flow??
Finally, we gained the most HP on the Dyno by adjusting the curve on the Distributor and jetting the carb. We started out at 390 HP and got to over 450 by making those adjustments. As most engine builders will tell you, all of the parts need to work together. These performance parts make engines move a lot of air and can be tricky on the timing. Everything needs to work together.
Hope this helps and if you have any questions, I will relay the information I can remember or perhaps someone with more knowledge can also come to my rescue if they disagree.
Brian