Word of the Day: Cross-Fire Injection

Cross-Fire injection was new for 1982 and found on Camaros and Corvettes. The setup featured a pair of throttle bodies mounted on an intake manifold that recalled the one found on the original Z28. This was trick-looking stuff that helped user in the modern era of fuel injection. 

Cross-Fire injection performed so well, in fact, that it was gone after the 1984 model year. (Okay, in reality GM’s Tuned Port Injection made its big debut for 1985.)

Photos courtesy RM Sothebys.

 

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Gearheadotaku
Gearheadotaku UltimaDork
1/24/20 10:44 a.m.

Just saw a performance manifold in Summit racing for this....

NickD
NickD PowerDork
1/24/20 10:59 a.m.

The graybeards at my work referred to them as "Cease-fire Injection" and "Misfire Injection". According to them, they never ran properly off the showroom floor

jorcane
jorcane New Reader
1/24/20 11:11 a.m.

 Nick you beat me to it! I cant remember what old article I read, but I still laugh when I think of crossfire being referred to as cease fire injection. Wasn't this still available in the c4?

Saron81
Saron81 Reader
1/24/20 11:16 a.m.

In reply to jorcane :

84 only I believe. 

Ranger50
Ranger50 UltimaDork
1/24/20 1:53 p.m.

Only time in "modern" times that it was acceptable to go backwards and put a carburetor on.

Vigo
Vigo MegaDork
1/24/20 1:54 p.m.

82 and 84, so technically it was both a c3 and c4 thing. I actually actively want an 84 c4 that still has a complete crossfire setup. I'm completely confident i can make it better than good enough. cheeky

bentwrench
bentwrench SuperDork
1/24/20 2:07 p.m.

If it was not throttle body injection it would be fine.

I can fix that...

Mod the manifold for port injection and rock and roll.

pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
1/24/20 2:25 p.m.

In reply to bentwrench :

I read on The Internet, so you can trust that this next bit is true, that the Cross-Fire manifold is dead on a 350 by 4500 RPM.  It's another one of those situations where Chevy/GM put pretty decent truck engine parts in their sporty cars and called it a day, only this time the system wasn't reliable either.  I think I'd rather go scrounging for a TPI setup or mod some 3rd party single-plane intake to add injection to.  Or just revert back to a carb. 

bobzilla
bobzilla MegaDork
1/24/20 3:23 p.m.
Vigo said:

82 and 84, so technically it was both a c3 and c4 thing. I actually actively want an 84 c4 that still has a complete crossfire setup. I'm completely confident i can make it better than good enough. cheeky

Dad had one. It ran good. All the torque of a TBI 350 and non of the fun of a sports car engine. His had the 700R behind it. 

bentwrench
bentwrench SuperDork
1/24/20 3:24 p.m.

Not sure a TPI flows much better....

But at least port injection cures the evil that throttle body injection is.

bobzilla
bobzilla MegaDork
1/24/20 3:24 p.m.
pres589 (djronnebaum) said:

In reply to bentwrench :

I read on The Internet, so you can trust that this next bit is true, that the Cross-Fire manifold is dead on a 350 by 4500 RPM.  It's another one of those situations where Chevy/GM put pretty decent truck engine parts in their sporty cars and called it a day, only this time the system wasn't reliable either.  I think I'd rather go scrounging for a TPI setup or mod some 3rd party single-plane intake to add injection to.  Or just revert back to a carb. 

TPI would have been a fantastic motor home engine. All that torque. No need to rev. They were also done around 4500rpm in stock form. 

Stefan
Stefan MegaDork
1/24/20 3:37 p.m.

In reply to pres589 (djronnebaum) :

Puts into perspective all of the nonsense around having a "Corvette" engine in their vehicle, eh?

In other words, unless its an LT5 or one of the LS variants, its not much to write home about.

noddaz
noddaz SuperDork
1/24/20 3:49 p.m.

New for 1982?  In 1982 I was driving a 1970 VW Type III that had fuel injection.  laugh

Duke
Duke MegaDork
1/24/20 3:50 p.m.

And, I believe, the start of GM's weird insistence on putting the entire 'features' list in badging on the outside of the car.

 

spitfirebill
spitfirebill MegaDork
1/24/20 3:53 p.m.
NickD said:

The graybeards at my work referred to them as "Cease-fire Injection" and "Misfire Injection". According to them, they never ran properly off the showroom floor

I've heard it referred to as the No-fire Injection.  

RealMiniNoMore
RealMiniNoMore PowerDork
1/24/20 4:00 p.m.
Duke said:

And, I believe, the start of GM's weird insistence on putting the entire 'features' list in badging on the outside of the car.

 

1980 Camaro Z/28 had AIR INDUCTION on the hood bump, with flappers at the back of the cowl that opened up at full throttle. (My ex-wife had an '81 with that.)

NickD
NickD PowerDork
1/24/20 4:04 p.m.
RealMiniNoMore said:
Duke said:

And, I believe, the start of GM's weird insistence on putting the entire 'features' list in badging on the outside of the car.

 

1980 Camaro Z/28 had AIR INDUCTION on the hood bump, with flappers at the back of the cowl that opened up at full throttle. (My ex-wife had an '81 with that.)

That was cooler than when they started putting ABS on every center cap on every car.

Stefan
Stefan MegaDork
1/24/20 4:06 p.m.
noddaz said:

New for 1982?  In 1982 I was driving a 1970 VW Type III that had fuel injection.  laugh

Um, the original C1 had fuel injection as an option.

Coupefan
Coupefan Reader
1/25/20 9:56 p.m.

The C1's mechanical continuous flow fuel injection was downright primitive and continuously squirted gas into the intake through a static 'nozzle'.  The VW's Bosch unit while primitive, more closely resembles a modern, controlled pulse, fuel injection system, utilizing a modicum of electronics. 

Here's some old technical papers on the Chevy injection:

http://www.oldcarbrochures.com/static/NA/Chevrolet/1959_Chevrolet/1959_Chevrolet_Fuel_Injection/dirindex.html

 

Vigo
Vigo MegaDork
1/25/20 10:30 p.m.

The C1's mechanical continuous flow fuel injection was downright primitive and continuously squirted gas into the intake through a static 'nozzle'. 

Yes, similarly primitive to the systems diesels continued to use for almost 40 more years. cheeky

 

TPI had a hell of a lot more 'curb appeal' with the hood popped for sure but it wasn't much more powerful than Crossfire and i'd rather rock a funky  rare dual TBI unit  that other people can't figure out how to make work right than a plain jane boring TPI setup that functions fine but is only... fine.  My .02

A 401 CJ
A 401 CJ Dork
1/25/20 11:38 p.m.

What exactly makes TBI evil?  It worked on GM trucks for eons.  What about it exactly makes it no good?  I get that some implementations of it may have been flawed, but I don't buy that there is any inherent flaw in it.  Am I wrong to think that?

Stefan
Stefan MegaDork
1/25/20 11:58 p.m.
A 401 CJ said:

What exactly makes TBI evil?  It worked on GM trucks for eons.  What about it exactly makes it no good?  I get that some implementations of it may have been flawed, but I don't buy that there is any inherent flaw in it.  Am I wrong to think that?

It's better than a carb, just barely, mostly because it is less bothered by extreme angle or g loads and it self-adjusts for changing air pressure.

That said, it dumps fuel into the intake where it can very easily pool or puddle in the runners making all that atomization effort worthless.

Some implementations mounted the injector in the airstream, making it a restriction.

For a lazy, low revving truck motor, it's a great solution over a carb when you want it to work fairly reliably.

For a sportscar motor?  It could work, but it would need some effort applied to make it as good as a port injection system where the fuel can be delivered to the backs of the intake valves and you can shape the intake to deliver the air instead of the entire charge.

Knurled.
Knurled. MegaDork
1/26/20 12:13 a.m.
NickD said:

The graybeards at my work referred to them as "Cease-fire Injection" and "Misfire Injection". According to them, they never ran properly off the showroom floor

The guy I worked alongside for 15 years knew how to make them work well.

 

He never told me all of his secrets, but he did let on that getting the throttles synchronized properly was absolutely critical.

Knurled.
Knurled. MegaDork
1/26/20 12:15 a.m.
Coupefan said:

The C1's mechanical continuous flow fuel injection was downright primitive and continuously squirted gas into the intake through a static 'nozzle'.  The VW's Bosch unit while primitive, more closely resembles a modern, controlled pulse, fuel injection system, utilizing a modicum of electronics.

The Rochester fuel injection system was purchased by Bosch and refined into the system we know and love as K-Jetronic, which was used as recently as 1994, on Porsche 911 Turbos.

Bosch marketed K-jet as the upmarket, refined fuel injection, and D-jetronic (what the VW had) as the cheap model.

 

It should be noted that D-jet used a second set of points in the distributor to trigger the injectors...

Knurled.
Knurled. MegaDork
1/26/20 12:21 a.m.
A 401 CJ said:

What exactly makes TBI evil?  It worked on GM trucks for eons.  What about it exactly makes it no good?

It has the wet-flow manifold problems that carburetors have, without the benefits of good atomization.

 

A carbureted intake can ice over on the outside on a humid day because of the heat of evaporation and the excellent atomzation.  You'd never see that with TBI and its staccato splurts of fuel blobs.

 

Carbs generally will make more power than EFI because of the excellent atomization, despite the pressure drops required for carbs to work.  They might not be able to make as broad of a powerband, but for peak power carbs are still where it's at.

David S. Wallens
David S. Wallens Editorial Director
1/26/20 9:54 p.m.
Duke said:

And, I believe, the start of GM's weird insistence on putting the entire 'features' list in badging on the outside of the car.

 

Hmmm, didn't think about that, but now that you mention it.... (I'm sure someone will find an earlier one, but that got me thinking.)

OLDMOTORHEADTED
OLDMOTORHEADTED
1/27/20 12:08 p.m.
David S. Wallens said:
feature_image

Cross-Fire injection was new for 1982 and found on Camaros and Corvettes. The setup featured a pair of throttle bodies mounted on an intake manifold that recalled the one found on the original Z28. This was trick-looking stuff that helped user in the modern era of fuel injection. 

Cross-Fire injection performed so well, in fact, that it was gone after the 1984 model year. (Okay, in reality GM’s Tuned Port Injection made its big debut for 1985.)

Photos courtesy RM Sothebys.

 

Read the rest of the story

Crossfire two throttle bodys= junk never ran properly from day one on going problems. Two years only on F&Y Bodys  Single throttle great system lasted years.

Tony Sestito
Tony Sestito PowerDork
1/27/20 12:40 p.m.

From what I've read, one of the biggest issues with the Crossfire setup was the intake manifold itself. It was originally conceived with a different runner design with larger ports, but the production ones got a neutered version of the original. They do make replacement manifolds for them, which wake them up quite a bit.

Another thing to consider is that EFI back in the early 80's was still a relatively new thing. It's easy to blame new technology and call it "junk" when there's a lack of understanding for how it works, and that's something that did happen. Sure, having two throttle bodies upped the complexity, but I still hear people crap on anything with a computer for being "junk" because "you can't fix it" because they don't take the time to learn how. I know people even today that refuse to drive cars made after the 1970's because they say that "computers ruin cars", "they aren't reliable", and that they are "impossible to work on".

All that said, I'd rather have modern MPFI every time. And I still want a Crossfire 3rd Gen Z28 or 1984 Vette just for the weirdness factor!

81cpcamaro
81cpcamaro Dork
1/27/20 1:17 p.m.

Crossfire intakes had the smallest intake ports of any SBC, about haft the size of normal. That really killed the power. Supposedly done for driveability.

Here is a site where someone modified one, you can see the port size Here

Ironically I was researching Crossfire setups years back when I ran across the Offy crossram setup, which I ended up with on my El Camino and then 81 Camaro CP car. I still have the intake/carb setup.

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