hi guys, I have a 84 corvette with the dreded crossfire injection.I got a spare intake manafold to port out and re install in the hopes of gaining alot more hp at the wheels. my car in current form spit out 166hp and 237fp torque on a local chassi dyno. realley pathetic.here is a pic of one port stock and one that has been port matched.I know that getting more air flow is the most important part of porting out the intake, and from that pic ^ you can see how terrible it must be factory stock.here is more of my progress,here is a pic of the egr "hump" being ground off. it is rough in the pic, but I have fully smoothed it out since,another problem with the intake is the runners are patheticly small. there is not enough meat in the casting to open them up enough to make any sizeable diffrence any ways, I was wondering if I opened up a "port" from one intake runner to the next allowing both runners to supply air/fuel to one head port. - the blue is where I would port thru the runner, and the red would be air flow,the image I drew on the left is a cut away view of how I think it would work the best, no harsh angles, just nice air flow path, from both small runners leading in to the newly opened up intake passage to support much more flow.what do you think about that idea? any feedback is more than welcome.and finaly, my last question, the intake has alot of casting flash and humps that I am in the process of grinding off. when its all said and done, do you think I should try and polish the entire inside of the manafold as smooth as humanly possible, or do you think leaving it a little bit rough will be better to promote the fuel to stay mixed with the air better?thanks for the look, please give me any advice you can!
Making a "window" from port to port would be a quick way to lose power. It opens up the door for distribution and reversion problems, it could screw up the wave tuning royally as well, don't do it!
i was thinking about this a while back... how about installing dual two barrel throttle body housing on top of a spare plate... since various sizes of the dual throttle bodys are available...from 2.8v6's to 7.4Llooking at the top of the lower manifold runners...... hmm how about milling out the top of the long runner and welding in a bent piece of flat aluminum to enlarge the runner size. maybe even make it tapered... as that i my mind would increase the speed of the airflow as it got back to the narrower factory crosssection..increasing in speed as it gets l closer to the port... since air is being sucked into the runner just having it flow thought the same diameter runner is in my mind an inefficant design... the idea of the air getting into line and then straighter and straighter as it closes in on the intake port just makes sense to me... some days i feel like tesla..ideas way before it's time...
woah.Do you have a Flow bench? or is this "home style" symetrical porting.i.e it looks good and neat so it's gotta work? If so,no,no. You may have lost significant power if ,flow loses contact with port and manifold walls,it stalls causing a change in the draft as set by factory.I'd get if you can,another set of heads and intake and DONT TOUCH EM'.A proffessional porting job or aftermarket intake would solve your problems.You can't guess porting and bigger does'nt mean more power.Read "what makes a 305 pull like a train" it has a wealth of info about these subjects.
From the outside it kinda looks like a cool rat roaster type manifold. But from the inside.......well what a peice of rubbish! the intake side of those runners look like they would starve a brush cutter. As for the head side, it is probably pointless to open them up when the intake side of the runner is so small.You will probably find that the fill area you removed will give little gain due to the lack of flow across the standard heads port floor anyway. Largely exacerbated due to the terrible approach angle on those runners.Sorry to say I would have binned it before even having a go at making something out of it.Finally a part that makes my old 273 2 barrel manifold look good.
Ditto every one else here.Those runners were small to help keep velocity up and mixture in suspension.GM has done many stupid things to cars over the years(cross fire vette intake set up) to name one but they crutched it to make it work.dude you just kicked the crutch out from under the general.Good luck.hope it works for you.
Power is bliss Torque devine
wow.. my new hr mag came in and sat a while.. they have an artical on a new edelbrock supercharged motor with a lower manifold that looks like this crossfire except...the runners are are as i described... like short funnels... have a look...
this is an old post i know.. i just wanted to include the image of the intake from the hot rod article