What are the different injection systems on C-4's capable of supporting with injector changes etc. I want to build at least a 406 cid, but more likely a 430 cid engine with agressive cam, good aftermarket heads, around 10.5 to 11.0 compression, and what ever I need to do to fuel system. Any suggetions? Thanks Billy.
I like the HSR for it's torque compared to the single planes and the miniram, but for a peaky high RPM race engine, the miniram makes a few more HP with it's shorter runners. For a high RPM street/strip, I use the HSR. The single plane might lose some midrange compared to the HSR, but it's easier to adapt to fit (though still not easy), unless you can find or fab a plenum for the HSR.
The engine size will drive the intake port and gasket sizes as they get bigger from 1204 to 1205 to 1206. I had to weld my HSR and port it to fit the 1206 gaskets on my 200 CC heads for my 383. For your 430, use a 1206, and, assuming it's a street car where you care about midrange torque, use a ported HSR if you're up for a challenge to get one to work, or use a miniram as it's a little easier and the torque loss isn't horrible. The single plane would be ok, too, but both that and the miniram will be down some torque compared to the HSR. The article referenced above is a great source. I actually plotted all the charts out in excel and studied them pretty closely for a few days as I did research on the different options.
Are you talking about intakes or fuel injection systems? As far as injection systems go, C4's had a few:
'84 crossfire (twin tbi) - limited tuning capability just because it isn't that popular and you only have 2 injectors that would need to be huge to support any HP.
'85 Tuned Port - this year only had a digital MAF sensor and tuning is also harder/limited because it's a 1-year only thing. Not as much info out there on it.
'86-'89 Tuned Port - MAF system with some changes year to year. These can only directly read airflow into the 250-275hp range due to the MAF sensor used and a limitation in the computer. However, it will support as much HP (800+?) as a set of high impedence injectors will allow (I think they make 75lb 'ers now - don't know how that will idle) through adding fuel in an area of the calibration called "power enrichment".
'90-'91 Tuned Port - did away with the MAF sensor and infers airflow based on engine vacuum, RPM, and other things. Like above, can support as much HP as high impedence injectors will fuel. Unlike the '86-'89 setup, this can be done directly (without resorting to tricks to fool the computer) in non-boosted applications.
Not as familiar with the '92+, but the same comment about supporting as much HP as high impedence injectors allow applies.
The only hitch for all of these systems is tuning a smooth idle can be difficult with long duration/short LSA cams (i.e. aggressive) due to intake reversion caused by the high overlap.
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C-4 injection systems and stroker motors
