82-84 Corvette Crossfire SBC Manifold

[BOSSMAN]

Anybody ever deal with one before? I'd thought that I would share a project that I'm working on for a guy that wants to get more performance out of his stock manifold (keep it stock appearing) to gain what he can. These things are horribly restricted so I decided to have my way with one to see what I could do to make it better, here is what has been done to date.

Stock condition.

Notice the very large EGR passage.

Notice the restrictive port to the head.

I angled the runners back to get the incoming charge easier from above. Runner length was trimmed back slightly.


I reshaped the runner entries and kept a nice radius to them.


I trimmed back the EGR passage and now working on blocking all of that stuff off, next a little bead blasting to clean it all up before a little high temp epoxy is applied.

More progress later.

[SuperBuickGuy]

interesting.... I always wondered whether those things could give a cross ram manifold a run for its money. Keep us updated (or at least keep me updated)

[BOSSMAN]

Will do! They say similar mods to what I'm doing can knock the ET down .3 - .5 in the quarter. It doesn't surprise me after really digging into it.

[Stich496]

they work great on 327's with a aftermarket ecu and the nos hidden in the ports..

[A/Fuel]

I've never really paid that much attention to those, but what you did there looks like something that should have been done at the factory. The results should be interesting.

[milner351]

Neat stuff - we dealt with one of those on the dyno in college - if you call dealing with it - taking it off and putting on a single carb manifold!

Sure looks like what you did should help!

Are you removing the EGR completely?
I would think just eliminating that heat from the intake would help reduce intake air temps and help power output.

[BOSSMAN]

Yes, eliminating the EGR completely and blocking all ends of the passages in the manifold.

[Scott Liggett]

I worked with a mechanic that had an 84 Camaro with one of those cross fires. He told me that he butchered the entire inside of the manifold and started over. I never saw what he did, but saw the results. The car was insanely fast and still passed emissions.

I always wanted to try building one using the old 302 cross ram intake and a better efi computer.

[Mater]

interesting. always thought it would be cool to moddify one for a multi carb set up becuase they can be found cheap on ebay

never saw inside oen though interesting

[jays67]

I have one I did a single carb and dual carb set up for never got around to finishing it I will snap some pics later I was going to put it on a 335 I built a few years back

[daved931]

Cool upgrades. Definitely curious to see the seat of the pants results.

My friends and I mostly call that the cease-fire injection setup. HP numbers were pretty anemic for those years (205?).

In the back of my mind, I've always thought it would be fun to snag an early C4 and put an upgraded engine in it. The chassis has potential and you can buy a used C4 relatively cheap.

[BOSSMAN]

Somebody JB Welded a crack on the water neck passage but now its fixed with a weld.

Trimmed back even more of the EGR Passage (it is completely eliminated) and have it all welded up now. Just need to smooth some of the areas out and work on the port matching. The manifold is now more evenly shaped on all four corners. Almost done with this one, on the home stretch.

[milkovich]

I love this type of stuff! Nice weld on the crack too. My 175 won't cut it on something that thick. You must have some decent power going (and a lot of skill).

[JeffMcKC]

It would be cool to run pipemax on it to see if you could tune the lenght of the port by cutting it back or adding to it. The taper might be helped by just cutting it off even and adding in your own runners, looks fun to try on for sure.

[BOSSMAN]

I love this type of stuff! Nice weld on the crack too. My 175 won't cut it on something that thick. You must have some decent power going (and a lot of skill).

I wish I could weld like that, had a local guy do it for me and he has a real big Miller Tig. As time goes on I hope to learn for myself though, I just know too many good welders to save on time.