Porting the Crossfire Intake on an '84

[benevolentelephant]

Hi There -

I've just found this forum.....I bought an '84 coupe a few weeks back, and have been trying to find some info about increasing the power. Nothing crazy, I'd really like 240-280hp for road driving.

Now, what I'd normally do would be cams, headers etc, BUT I've just moved to California, and the law here means that's out.

SO: a helpful guy on another forum suggested I port the intake, said it would result in some hp gains.

My question is, how much gain can I expect from a simple porting? Are there other 'invisible' mods I can make to go along with it to increase the potential?

Any info appreciated!!
Thanks
Bruce

 

[topless82vette]

buy a set of TPIS long tube headers and there 3 inch cat back. My friend put them on his 90 vette and there was an immediate difference. All the stuff is smog legal as well.

Personally though I'de give up on porting CFI. Just a waste of time, I would say since CFI is a MAP based batch fire injection system just re-pin your ECM connectors and modify your existing harness a little and run speed density TPI. Or run a X-ram with an external EGR system.

 

[proj84vette]

Don't forget that with the TPI, you'll also need 083 heads or the later 113 heads and
a cam that came with the L98 from 1985 or 1987. Bolting the TPi to your L83 will not
make 230hp with our smog heads.

 

[killain]

buy a set of TPIS long tube headers and there 3 inch cat back. My friend put them on his 90 vette and there was an immediate difference. All the stuff is smog legal as well.

Personally though I'de give up on porting CFI. Just a waste of time, I would say since CFI is a MAP based batch fire injection system just re-pin your ECM connectors and modify your existing harness a little and run speed density TPI. Or run a X-ram with an external EGR system.

You can port and polish the intake, but it has a very minimal effect, plus you need to be careful as the Crossfire stock manifold doesn't have a lot of sidewall material. The best thing you can do, (I assume in California, however they change the smog laws weekly)? is to upgrade to an 85 -87 fuel pump, get a better set of milled injectors and install a slightly better cam and headers and free flowing exhaust. . . AND a rebuilt and upgraded ECM. these and other item for the crossfire can be had from a vendor atwww.Turbocity.com 714-639-4933 @ 1137 W. katelle Ave, Orange CA 92867

There's a lot to raise the HP output from a crossfire including the Xram intake maifold www.x-ram.com

 

[Hib Halverson]

There won't be much gain by just "porting" the intake alone because while the intake manifold on an 84 isn't a very good design, there are other reasons the engine only make 205 hp.

As is said earlier, you need to be careful when hand porting the 82-84 intake manifold because it's port walls are thin in some cases. In fact, if you're going to insist on modifying the intake, I'd have it Extrude Honed. Once you consider your labor in hand porting, the cost of that won't be much different and the Extrude Hone process is a great choice where you want to remove a limited amount of material from ports and have the port walls smooth.

From there, I'd free up the exhaust with a more performance-oriented cat and lower restriction mufflers. Technically, headers are not legal for that car in California but in most cases of the California smog check, if you have headers connected to a stock cat, the rest of the emissions controls are present and working and the car passes the enhanced smog check you'll be ok.

You also can change the camshaft and as long as you don't get to radical on your profile choice it can pass smog provided that the ECM calibration is right.

You put a mild hyd. roller in the engine, add headers and a low restriction exhaust, Extrude Hone the intake and top that off with the right cal and you're going to have more performance. Will it be 280 hp? Probably not. For that, you have the wrong engine, but I think 230-240 is certainly possible.

To get that 240+ and still pass the smog check will probably require upgrading to a newer engine configuration.

 

[killain]

There won't be much gain by just "porting" the intake alone because while the intake manifold on an 84 isn't a very good design, there are other reasons the engine only make 205 hp.

As is said earlier, you need to be careful when hand porting the 82-84 intake manifold because it's port walls are thin in some cases. In fact, if you're going to insist on modifying the intake, I'd have it Extrude Honed. Once you consider your labor in hand porting, the cost of that won't be much different and the Extrude Hone process is a great choice where you want to remove a limited amount of material from ports and have the port walls smooth.

From there, I'd free up the exhaust with a more performance-oriented cat and lower restriction mufflers. Technically, headers are not legal for that car in California but in most cases of the California smog check, if you have headers connected to a stock cat, the rest of the emissions controls are present and working and the car passes the enhanced smog check you'll be ok.

You also can change the camshaft and as long as you don't get to radical on your profile choice it can pass smog provided that the ECM calibration is right.

You put a mild hyd. roller in the engine, add headers and a low restriction exhaust, Extrude Hone the intake and top that off with the right cal and you're going to have more performance. Will it be 280 hp? Probably not. For that, you have the wrong engine, but I think 230-240 is certainly possible.

To get that 240+ and still pass the smog check will probably require upgrading to a newer engine configuration.

Upgrading to 240+ horsepower will require relocating to another state !:L

 

[Hib Halverson]

Perhaps but I still think the 82-84 "crossfire" engine can be mod'ed up to 230-240 hp and still pass the smog check, but...and it's a big but...it will take someone who knows how to calibrated the engine once the mods are complete.

I took a 01 Camaro with a V6 from 200 to 270 and stayed completely smog legal. In fact, the last time I had it checked, the technician said it was the cleanest car he'd ever seen modified to the level that it is. One key part of the project was the role Z-Industries had in doing the cal.

In short..."Cal is King". The problem is many people either don't want the pay the money it costs to do good cal work.

 

[killain]

Perhaps but I still think the 82-84 "crossfire" engine can be mod'ed up to 230-240 hp and still pass the smog check, but...and it's a big but...it will take someone who knows how to calibrated the engine once the mods are complete.

I took a 01 Camaro with a V6 from 200 to 270 and stayed completely smog legal. In fact, the last time I had it checked, the technician said it was the cleanest car he'd ever seen modified to the level that it is. One key part of the project was the role Z-Industries had in doing the cal.

In short..."Cal is King". The problem is many people either don't want the pay the money it costs to do good cal work.

I was only kidding Hib, I know that there is a LOT of talent out in California. And yes, it's a lot of work, but I have talked to a lot of guys who have gotten 240 HP and up out of a crossfire. One guy in Finland even turbo'ed a CFI to the tune of 570 hp. But for the average guy or gal, CFI in the 82 to 84 Vette isn't going to get more than 240 out of the crossfire. The entire car has too many limitations to try to get anymore than that within reason. The chase isn't worth the run.

 

[Hib Halverson]

Whether or not the chase is worth the run depends on how much one likes the 2xTBI set-up on 82s and 84s.

 

[xrcrx]

I would have to respectfully disagree with extrude honing the Crossfire intake. As a wet flow intake the surfaces will tend to be too slick. There is also the extreme cost to consider. Porting or having the CFI intake ported is quite a bit less. My personal experience shows no loss on the bottom end and gains in the middle and top. Overall gain in the 1/4 was half a second. Iwould agree that just porting the intake would probably be a disappointment. Adding 1.6-1 roller tipped rockers will, get more out of the intake and greatly enhance the drivers sotp feel! Those two mods alone are worth a full second drop and almost 10 mph!

 

[xrcrx]

btw, the crane 2040 cam is Cal friendly and has a CARB#, not so sure about heads, but my car passed the Texas sniffer test with flying colors. Lotsa room top spare.

 

[Whorn]

buy a set of TPIS long tube headers and there 3 inch cat back. My friend put them on his 90 vette and there was an immediate difference. All the stuff is smog legal as well.

Personally though I'de give up on porting CFI. Just a waste of time, I would say since CFI is a MAP based batch fire injection system just re-pin your ECM connectors and modify your existing harness a little and run speed density TPI. Or run a X-ram with an external EGR system.

please tell me how I'd get info on re pinning the ECM

 

[WhalePirot]

Hi There -

I've just found this forum.....I bought an '84 coupe a few weeks back, and have been trying to find some info about increasing the power. Nothing crazy, I'd really like 240-280hp for road driving.

Now, what I'd normally do would be cams, headers etc, BUT I've just moved to California, and the law here means that's out.

SO: a helpful guy on another forum suggested I port the intake, said it would result in some hp gains.

this is how I started, over a decade ago. My car always passed SMOG (well almost always).

Turbo City advised me to NOT mess with the intake.

I have run long tubes for decades with the AIR injection and a stock CAT. I had Z-man do my chip after I re-cammed the engine and enlarged the T/Bs, but he was less than enthusiastic about it. It is a royal PITA vs the newer cars, whose chips do not need to be removed, erased and reburned. After taking a LOT of fuel out my ECM tables, the car still ran rich and eventually fouled the CAT.

I had changed to a 3.73 rear, which I did not like, due to the low RPM rev capability of the L83, even somewhat modded. Those stock intake ports are TINY.

Each step on my journey made the car a bit faster, but eventually I hit the wall (the intake). There are more options these days, so I may hang the TBI on a 383 stroker, going into a "55 Effie. (I must like pain.)

 

[xrcrx]

Porting the stock intake will net a quarter mile time thaty is about .5 better than what you have with the stock intake and a gain of 4 or 5 mph trap speed. You will also gain about 400 more useable rpms. The only reason i can see for Turbo City to suggest leaving the intake alone, considering the success I and many others have had, is because you run the risk of irreparable damage to the intake floor if you do not know what you are doing. though it really is not that hard. The ported intake won't lose you low end torque like the x-ram while netting gains throughout the rpm band, but most effective on the top end. Be prepared to convert to a 7747 or similar ECM that has been reworked to be tuned if you decide to do a crossfire 383. The stock ECM will not support it.

 

[nelson84]

There is another intake soon to be released and I am not talking about the x-ram or the sy1 or the offy. It is made by "dynamic crossfire solutions" and it is called the "renegade". They are in the final stages befor releasing it. I have seen photos of it on the crossfire injection forum. They have not yet shown pictures of the inside of the intake, but it is a true cross ram design according to this company. They just want to tweek it to squeeze maximum power out of it before they release it.

 

[killain]

There is another intake soon to be released and I am not talking about the x-ram or the sy1 or the offy. It is made by "dynamic crossfire solutions" and it is called the "renegade". They are in the final stages befor releasing it. I have seen photos of it on the crossfire injection forum. They have not yet shown pictures of the inside of the intake, but it is a true cross ram design according to this company. They just want to tweek it to squeeze maximum power out of it before they release it.

I believe this is perhaps a great change on the way, however I've never seen or read anything about it, but will as It might help me. You can do a lot of things including the exhaust and a very mild cam, but the big problem with the crossfire as well as all L-83's is the intake. You can install, and i would recommend rebuilt bosch injectors with a greater flow rate as well as installing a 87 puel pump which puts out more PSI than an 84 pump and Have the throttle bodies rebuilt with the throttle shafts drilled out and bronze bushings installed on the shafts and the throttle bodies themselves can be bored out to a full two inches. This will give you a little better intake volume. The ECM can be rebuilt with a better board and recalibrated and finally a Hypertech chip installed or any other chip manufacturer. But the big problem is the intake manifold. In fact it is a little known fact that the intake manifold on the L-83 is actually the manifold was designed to have the throttle bodies facing the opposite direction. ( It was designed and sent out for production in late 80 or 81 and 30K of them had been cast and delivered when the mistake was found and it was too late to anything about it then, that is why the throttle cables are so long) I'll look to see if I still have the article about it. But if you want 240 HP that is very possible and I even know someone who turbocharged their 84 TBI with great success to the tune of 500HP. FWIW

 

[geekinavette]

You can install, and i would recommend rebuilt bosch injectors with a greater flow rate as well as installing a 87 puel pump which puts out more PSI than an 84 pump

It should be noted that installing higher flow injectors WILL require a computer calibration change.

Also...to be correct in terminology...installing a later TPI pump will NOT change the fuel pressure, that is determined by the fuel pressure regulator. What they WILL do however is provide more flow, thus allowing the fuel pressure to better remain stable under heavy load conditions. It is a great "upgrade" to do as the stock 84 pumps are barely able to provide enough flow even for a stock CFI engine.

 

[CorvetteArchives]

It should be noted that installing higher flow injectors WILL require a computer calibration change.

Also...to be correct in terminology...installing a later TPI pump will NOT change the fuel pressure, that is determined by the fuel pressure regulator. What they WILL do however is provide more flow, thus allowing the fuel pressure to better remain stable under heavy load conditions. It is a great "upgrade" to do as the stock 84 pumps are barely able to provide enough flow even for a stock CFI engine.

Yes, Definitely the BEST thing to do first is the fuel pump...it really woke up my car! Makes it consistant!
.........and before anyone begins asking where the Fuel Pressure regulator on a 84 is.... there isnt one in an 84 like on a TPI...its adjusted at the throttle body on CFI cars.....something Geek knows...it just didnt come out clearly...

 

[nelson84]

Did you guys change your fuel lines to metal or did you leave the original rubber lines?

 

[geekinavette]

Well...of course CFI DOES have a fuel pressure regulator...any form of fuel injection does. It is just integrated into the rear throttle body assembly, so doesn't really "stand out" like a TPI regulator would.

nelson84...which lines are you talking about? The "original" lines are a combination of metal and rubber.