1984 Corvette Removing Crossfire
Thread Starter
Heel & Toe
Joined: Apr 2008
Posts: 19
Likes: 0
Why? Based on what criteria?
My CFI Trans Am made OVER 300 hp, got OVER 24 mpg on the highway w/3.45 gears and idled like stock. What is "horrible" about that??
ALL my mods cost me less than $1500.00 and all the mods to the INDUCTION system cost me less than $200.00. Based on the above criteria, what is "horrible" about that??
My CFI Trans Am made OVER 300 hp, got OVER 24 mpg on the highway w/3.45 gears and idled like stock. What is "horrible" about that??
ALL my mods cost me less than $1500.00 and all the mods to the INDUCTION system cost me less than $200.00. Based on the above criteria, what is "horrible" about that??
Burning Brakes
Joined: Sep 2006
Posts: 1,202
Likes: 3
From: MD
If all he really wants is 300chp the crossfire can get him there. In fact, the crossfire can get him there relatively inexpensively. As has been said before, port the crossfire, change the cam, put on headers and a good exhaust, and get it tuned up real well and you'll be at 300hp. The stock heads can support 300chp.
That beig said, I did in fact bin my crossfire setup. I built a very healthy 383 (~425 chp) and for an engine like that crossfire does become a bit too much of a limitation and time-hog. I didn't want to spend the time programming a new ECM. If I had more modest hp goals I'd have kept the crossfire and the stock ECM, and gone with the above package. In fact, sometimes I wish I had (like right now when my car sits in my shop cause I'm still working bugs out).
Bottom line is, if he's looking for an easy 300chp engine keep the crossfire. The money and effort of re-pinning the ECM, changing the wiring harness, buying all the components, etc isn't worth it. He didn't say "I want 400 chp". If he does the above and finishes it with a gear swap and/or stall converter swap he'll have a car that will trash a stock TPI car at lights, plenty of fun, cheap, and every bit as reliable as the stocker was.
That beig said, I did in fact bin my crossfire setup. I built a very healthy 383 (~425 chp) and for an engine like that crossfire does become a bit too much of a limitation and time-hog. I didn't want to spend the time programming a new ECM. If I had more modest hp goals I'd have kept the crossfire and the stock ECM, and gone with the above package. In fact, sometimes I wish I had (like right now when my car sits in my shop cause I'm still working bugs out).
Bottom line is, if he's looking for an easy 300chp engine keep the crossfire. The money and effort of re-pinning the ECM, changing the wiring harness, buying all the components, etc isn't worth it. He didn't say "I want 400 chp". If he does the above and finishes it with a gear swap and/or stall converter swap he'll have a car that will trash a stock TPI car at lights, plenty of fun, cheap, and every bit as reliable as the stocker was.
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
What do you guys use to tune the stock ECM on those cars? I noticed tunercat doesn't have an available definition for them.
I know folks like Dom upgraded to a modified '747 TBI ECM to run his setup. I think Dom ran like mid 13s. I know there are some other guys who claim to run 13s with a crossfire, but their neighbors at the track have verified the cars only ran like 15s.
who knows.
The OP seems to have vanished, so maybe he got the answer he wanted, maybe not.
-- Joe
I know folks like Dom upgraded to a modified '747 TBI ECM to run his setup. I think Dom ran like mid 13s. I know there are some other guys who claim to run 13s with a crossfire, but their neighbors at the track have verified the cars only ran like 15s.
who knows. The OP seems to have vanished, so maybe he got the answer he wanted, maybe not.
-- Joe
Last edited by xrcrx; May 7, 2008 at 04:04 PM.
Thread Starter
Heel & Toe
Joined: Apr 2008
Posts: 19
Likes: 0
You guys are arguing over this ?? Here I'll answer his questions.
1. is there a good way to upgrade this engine?
Sure there is, heads, cam, exhaust the list goes on
2.If I removed the crossfire injection system and that crappy intake manifold, how much work would it be to install a more modern system?
It would be alot of work
3.Would I have to get a new PCM?
Assuming the PCM is an ECM then perhaps depends on what you end up doing.
4.Would it fit?
Which intake ? With the stock hood without cutting it ??
5. Do the LS crate engines fit?
Sure !! However that will be the least of your problems.
1. is there a good way to upgrade this engine?
Sure there is, heads, cam, exhaust the list goes on
2.If I removed the crossfire injection system and that crappy intake manifold, how much work would it be to install a more modern system?
It would be alot of work
3.Would I have to get a new PCM?
Assuming the PCM is an ECM then perhaps depends on what you end up doing.
4.Would it fit?
Which intake ? With the stock hood without cutting it ??
5. Do the LS crate engines fit?
Sure !! However that will be the least of your problems.
Yes, PCM is ECM...I work at Ford so we call it a powertrain control module. Are there aftermarket intake manifolds out there that fit under a stock hood without cutting it?
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
A stock Crossfire(mine)ran 15.3@88, no mods 110k miles. The cold air mod+K&N Filter-makes the underhood ductwork functional-and it ran 15.2 @ 89. 1.6-1 roller tip rockers and it was down to 14.7@ 93, porting the intake dropped it to 14.3@96. After that I added the Dart heads, Crane 2040 and 3.75 gears. It became a veritable rocket-on the original ECM at that point. The rings cratered at 127k and i have a 383 now. That requires a 7747, HAM board , EBL Flash and uses TunerPro for tuning. No new times yet. The stock ECM is useless so you have to upgrade to a later ECM and modify it to work with the existing harness, hence the HAM board.
I've been told the stock ECM is junk by guys who have tried to do stuff with them. Very similar to the CC carb ecm, correct? The '747 is not bad, that what I have in the truck. Its sort of feature limitted compared to the '730/'727 but it gets the job done for TBI.
-- Joe
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
And what is your 'real' goal? Is it simply to stand up to stock LT1 vettes, or are you gonna race this car ?
-- Joe
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
For the cost of some time and an intake gasket set porting the intake is worth about half a second and adds a few useable rpm up top. 1.6-1 roller tip rockers for less than 200.00 will be worth another half second and add power everywhere, much stronger response. So fo less than 300.00 he could have a low 14 second car requiring no ecm mods. A good torque converter would get it into the 13's!
Thread Starter
Heel & Toe
Joined: Apr 2008
Posts: 19
Likes: 0
No racing...I just want to make this car worthy of its skin. It's not worth it to throw a ton of money at it.
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Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
Neat. What is the cost associated with the '747 embedded lockers stuff? I'm using a '749 in my corvette due to boost. Just repined the harness to a '730 first when I was naturally aspirated, which uses the same pin outs as the '749. Whats the fuel firing on the crossfire, batch or quasi?
I've been told the stock ECM is junk by guys who have tried to do stuff with them. Very similar to the CC carb ecm, correct? The '747 is not bad, that what I have in the truck. Its sort of feature limitted compared to the '730/'727 but it gets the job done for TBI.
-- Joe
I've been told the stock ECM is junk by guys who have tried to do stuff with them. Very similar to the CC carb ecm, correct? The '747 is not bad, that what I have in the truck. Its sort of feature limitted compared to the '730/'727 but it gets the job done for TBI.
-- Joe
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Easily achievable
port your intake- $0 except your labor
1:6 rrs $200
Headers- $400 - $700
Air Duct Mod- free
all this will equal a big smile
2200 stall- not sure of price
You want more
Dart Heads $625
2040 cam $140
I as well am now using the ebl/flash ecm. Very user friendly and I have no experience with tuning. It will pretty much tune itself to a point.
I
port your intake- $0 except your labor
1:6 rrs $200
Headers- $400 - $700
Air Duct Mod- free
all this will equal a big smile
2200 stall- not sure of price
You want more
Dart Heads $625
2040 cam $140
I as well am now using the ebl/flash ecm. Very user friendly and I have no experience with tuning. It will pretty much tune itself to a point.
I
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
My plans are to update the ECM when time allows (currently my time is taken up with completing the C4 suspension installation onto my spare '69 frame). The newer ECMs have more "flexible" software, which ought to make calibrating a turbo motor a bit easier.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
O.K. here it is:
Edelbrock headers: $125 From the Want ADvertiser(used)
Used, 400 long block: $400 Bucks
MSD injectors $100 From Ebay
Summit Cam: $80
Summit Roller Rockers: $150
Timing chain: $40
SLP Cat back: $300
"Underdrive" pullies: $3 Pulled off a '69 chevy pickup at a salvage yard.
Walbro 255 LPH fuel pump: $200
53mm TB's: Free. I did it myself
Ported intake: Free. I did it myself
VRFPR: $40
I'm at $1460.00. Might as well bring it up to $1500.00 for miscellaneous junk.
So for $1500.00 I got 13.5 @102. It should be noted that it took me a long time to accumulate all those parts.
On the other hand it should also be noted the money I put into the CFI induction system;
Gaskets
injectors
throttle plates
VRFPR
...About $220, plus labor for grinding.
Edelbrock headers: $125 From the Want ADvertiser(used)
Used, 400 long block: $400 Bucks
MSD injectors $100 From Ebay
Summit Cam: $80
Summit Roller Rockers: $150
Timing chain: $40
SLP Cat back: $300
"Underdrive" pullies: $3 Pulled off a '69 chevy pickup at a salvage yard.
Walbro 255 LPH fuel pump: $200
53mm TB's: Free. I did it myself
Ported intake: Free. I did it myself
VRFPR: $40
I'm at $1460.00. Might as well bring it up to $1500.00 for miscellaneous junk.
So for $1500.00 I got 13.5 @102. It should be noted that it took me a long time to accumulate all those parts.
On the other hand it should also be noted the money I put into the CFI induction system;
Gaskets
injectors
throttle plates
VRFPR
...About $220, plus labor for grinding.
Last edited by Tom400CFI; May 7, 2008 at 10:10 PM.
See, this is what I'm talking about, guys like xrcrx have already done the hard work for you with trial and error and sticking with it. This has been a great read.
Pro
Joined: Apr 2008
Posts: 694
Likes: 1
From: Spokane WA
O.K. here it is:
Edelbrock headers: $125 From the Want ADvertiser(used)
Used, 400 long block: $400 Bucks
MSD injectors $100 From Ebay
Summit Cam: $80
Summit Roller Rockers: $150
Timing chain: $40
SLP Cat back: $300
"Underdrive" pullies: $3 Pulled off a '69 chevy pickup at a salvage yard.
Walbro 255 LPH fuel pump: $200
53mm TB's: Free. I did it myself
Ported intake: Free. I did it myself
VRFPR: $40
I'm at $1460.00. Might as well bring it up to $1500.00 for miscellaneous junk.
So for $1500.00 I got 13.5 @102. It should be noted that it took me a long time to accumulate all those parts.
On the other hand it should also be noted the money I put into the CFI induction system;
Gaskets
injectors
throttle plates
VRFPR
...About $220, plus labor for grinding.
Edelbrock headers: $125 From the Want ADvertiser(used)
Used, 400 long block: $400 Bucks
MSD injectors $100 From Ebay
Summit Cam: $80
Summit Roller Rockers: $150
Timing chain: $40
SLP Cat back: $300
"Underdrive" pullies: $3 Pulled off a '69 chevy pickup at a salvage yard.
Walbro 255 LPH fuel pump: $200
53mm TB's: Free. I did it myself
Ported intake: Free. I did it myself
VRFPR: $40
I'm at $1460.00. Might as well bring it up to $1500.00 for miscellaneous junk.
So for $1500.00 I got 13.5 @102. It should be noted that it took me a long time to accumulate all those parts.
On the other hand it should also be noted the money I put into the CFI induction system;
Gaskets
injectors
throttle plates
VRFPR
...About $220, plus labor for grinding.
Pro
Joined: Apr 2008
Posts: 694
Likes: 1
From: Spokane WA
Pro
Joined: Apr 2008
Posts: 694
Likes: 1
From: Spokane WA
What about those swirl dealies? are they worth messing with? Some people hack them up a bit and some remove them. What do they actually do? Do they spin or sit in place. I think they are refered to as swirl viens or something like that?
Where you port the intake, is it worth it? What benifits and what draw backs are there? Will you notice it when you hit the gas?
Where you port the intake, is it worth it? What benifits and what draw backs are there? Will you notice it when you hit the gas?
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Gain= 30-40 hp on a free mod... well worth it
Mine isn't ported I use the X-ram. The gain on the x-ram alone was a good 35hp... documented. Ported will do the same if not more.
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
While I will agree that the stock ECM is not anything to brag about, I have to disagree that it is not tunable. I've been running a re-cal'd stock ECM on my '84 turbo 355 for years. Runs strong, and I've put over a thousand (road course) track miles on it. Like other ECMs, it's just a matter of having the code listings, measuring what the engine is doing, and then changing the calibration values. Time consuming, yes, but not difficult.
My plans are to update the ECM when time allows (currently my time is taken up with completing the C4 suspension installation onto my spare '69 frame). The newer ECMs have more "flexible" software, which ought to make calibrating a turbo motor a bit easier.
My plans are to update the ECM when time allows (currently my time is taken up with completing the C4 suspension installation onto my spare '69 frame). The newer ECMs have more "flexible" software, which ought to make calibrating a turbo motor a bit easier.
Safety Car
Joined: May 2006
Posts: 4,290
Likes: 140
From: Salem NH
While I will agree that the stock ECM is not anything to brag about, I have to disagree that it is not tunable. I've been running a re-cal'd stock ECM on my '84 turbo 355 for years. Runs strong, and I've put over a thousand (road course) track miles on it. Like other ECMs, it's just a matter of having the code listings, measuring what the engine is doing, and then changing the calibration values. Time consuming, yes, but not difficult.
My plans are to update the ECM when time allows (currently my time is taken up with completing the C4 suspension installation onto my spare '69 frame). The newer ECMs have more "flexible" software, which ought to make calibrating a turbo motor a bit easier.
My plans are to update the ECM when time allows (currently my time is taken up with completing the C4 suspension installation onto my spare '69 frame). The newer ECMs have more "flexible" software, which ought to make calibrating a turbo motor a bit easier.
an ECM.
Hows the turbo crossfire run? How much boost, and whats your fuel pressure look like while under boost?
-- Joe