David R.
Registered User
I want to modify a stock manifold to have a larger manifold volume, and internal tuned-length intake runners.
I've done a lot of research on other manifolds people have done and I see a lot of modification to the plenum and plenum flange on the manifold, but I've yet to see pictures of modification to the rest of it other than careful porting. Per suggestion I researched Randy Baker manifolds, and that's all I was seeing (that and dividers put in the plenum). Many of the older threads the pictures would not show up or they were removed altogether. I serached all the pages of "randy baker intake" and that's all I found. I did come across a manifold someone made from scratch for a whipple (I dont remember his name, but I'm sure many of you know him) that was quite impressive, but not really what I'm after or even remotely capable of.
I also read talk of moving to split port heads, which makes sense if you're already hacking up the manifold and have minimal money invested into single port heads (in my case $0.00). This obviously changes the runner cross section, which I understands puts peak torque at a higher rpm which may not be ideal with the roots style m90? (just a wild guess there).
I have also done a good bit of research on the whole ram-air effect thing. I see a lot of conflict about whether or not it applies in a forced-induction environment. As near as I can figure, and from what I've found, the concept is entirely valid on our cars. The main difference being at boost the speed of sound is faster, therefore the ideal runner length must be shorter (hey, that's exactly what we want).
Points of Inquiry:
1. If anyone has pictures of their modified manifolds, I would very much like to see what people have tried. I'm sure it's been done, but I can't find pictures anywhere. I saved a lot of links to prior discussions on the subject and general information on the concept of runner-length tuning.
2. Also, forgive me but I'm not well versed on split port heads. Are they steel? Are they economical? For a mild street build that I'm going for, it sounds like they already flow better then my back-yard porting job could offer on single-ports. I'll look into them more, but if you have ground-breaking information in favor or against them please weigh in.
3. Really any other information you think I'm missing here. I'm learning all of this online and sometimes I have no idea what else I should be considering.
Basically I'm going to build an intake, and am weighing the major factors before starting(general design, major stock problems, head choice, etc.).
I've done a lot of research on other manifolds people have done and I see a lot of modification to the plenum and plenum flange on the manifold, but I've yet to see pictures of modification to the rest of it other than careful porting. Per suggestion I researched Randy Baker manifolds, and that's all I was seeing (that and dividers put in the plenum). Many of the older threads the pictures would not show up or they were removed altogether. I serached all the pages of "randy baker intake" and that's all I found. I did come across a manifold someone made from scratch for a whipple (I dont remember his name, but I'm sure many of you know him) that was quite impressive, but not really what I'm after or even remotely capable of.
I also read talk of moving to split port heads, which makes sense if you're already hacking up the manifold and have minimal money invested into single port heads (in my case $0.00). This obviously changes the runner cross section, which I understands puts peak torque at a higher rpm which may not be ideal with the roots style m90? (just a wild guess there).
I have also done a good bit of research on the whole ram-air effect thing. I see a lot of conflict about whether or not it applies in a forced-induction environment. As near as I can figure, and from what I've found, the concept is entirely valid on our cars. The main difference being at boost the speed of sound is faster, therefore the ideal runner length must be shorter (hey, that's exactly what we want).
Points of Inquiry:
1. If anyone has pictures of their modified manifolds, I would very much like to see what people have tried. I'm sure it's been done, but I can't find pictures anywhere. I saved a lot of links to prior discussions on the subject and general information on the concept of runner-length tuning.
2. Also, forgive me but I'm not well versed on split port heads. Are they steel? Are they economical? For a mild street build that I'm going for, it sounds like they already flow better then my back-yard porting job could offer on single-ports. I'll look into them more, but if you have ground-breaking information in favor or against them please weigh in.
3. Really any other information you think I'm missing here. I'm learning all of this online and sometimes I have no idea what else I should be considering.
Basically I'm going to build an intake, and am weighing the major factors before starting(general design, major stock problems, head choice, etc.).