Crossfire intakes and throttle bodies

[Brenner]

I hope I am not creating a problem with this inquiry as I had asked in the C4 technical and performance forum with only one reply that did not answer my question as of yet. So I create this inquiry to this forum in hopes of learning the information I seek, perhaps I should of started here first and for this I apologize, I have no excuse but that I am new. My inquiry is that I own a 1984 crossfire and after reading much information I have decided that I want to port an intake for it. I really would like to keep the original that came with the car untouched incase I make any mistakes I can return the car back to original condition. In my search of keeping this car a low dollar budget build I have come across a 1982 corvette crossfire engine and my questions are, besides the different part numbers and different fuel lines I have read about are these two manifolds the same? Is one larger or better suited for my intentions? I do recognize they have different injectors, and I do recognize the difference in the F body car applications, and I am not without mechanical knowledge. Not having the intakes off or even both engines in front of me makes it hard to compare and visualize so I ask these questions. If anyone has experience or can answer my questions it would greatly be appreciated as the 1982 engine is two hours from me and if it will not suit my needs as a donor for the crossfire system there is no point of me going to get it. My car is extremely low budget with my current employment situation, my car came to me at little to no cost and I am a huge underdog fan and always wanted a crossfire for the challenge and also becuase in my experience most cannot make them run correctly. Thank you to all in advance for any effort you may do to assist me.

[xfirez51]

The manifolds are essentially the same. One mod done for the 84 motor was adding a opening in the common wall of adjacent runners. It looks a bit like a teardrop and was supposed to be
responsible for the additional 5hp. The Xfire is definitely a DIY project but there's plenty of
documentation on modding and making power from the Xfire. I personally built my Xfire to
a level of ~105mph trap, 285rwhp/347rwtq.

[Brenner]

Thank you for this information. If possible might you be able to point me in a direction of any information regarding this common wall opening? I have read about standard porting but I do not recall the opening information. If not thank you anyways as I will dig harder in effort to learn more. Atleast now I will not be as uncertain to purchase the 1982 donor engine. I would also like to thank you for sharing the limits you have reached with your build, it just supports my confidence that what I would like to do is possible. My mods will be done small steps due to financial reasons and time.

[XLR8]

Hi Brenner! I can't help with your technical inquiry but I wanted to take the opportunity to welcome you to the

Hope you enjoy your stay with us!
Jane Ann

[Yoda]

Brenner

We have a very knowledgeable crossfire (1984) member. He goes by geekinavette (Bill). Before his 84 went up in smoke, he did extensive modifications to his 84. I had the privilege of getting a ride in it during one of our early CruiseFests. Very strong with lots of torq.

I did a search for crossfire by geekinavette and came up with a few threads he posted, a couple (esp. the last two ) might be exactly what you are looking for Bill's Crossfire Threads

Bud

[geekinavette]

I swear I replied to this thread! Must've just typed and never got around to hitting "submit"!

I was just gonna mention the same thing xfire did...some had what most call "balancing" holes between adjacent runners, some did not. I don't think there's any documented evidence that one performs any differently than the other.

The 'ol crossfire CAN be made to perform...but it'll take much more than just intake. Exhaust, injectors, throttle bodies, heads, cam, ECM (tuning) all will need to be addressed. Remember the restrictive intake is not the sole factor in how this engine performs (or ANY engine for that matter)...it's a complete system and must be addressed as such or you will gain very little if anything at all.



Bud...oh how I wish you could have seen this thing before the roast-fest. <sigh>

[XLR8]

.........asked in the C4 technical and performance forum with only one reply

I swear I replied to this thread! Must've just typed and never got around to hitting "submit"!
...................
Bud...oh how I wish you could have seen this thing before the roast-fest. <sigh>

Relax Bill. You're not losing it... yet. You replied to his thread in the C4 forum: L83 intake manifold and throttle bodies, crossfire question

The thought of playing along crossed my mind but I guess I'm getting soft in my old age. Besides, at my age and loss of mental ability, you'd probably have plenty of opportunity to turn it around on me sooner rather than later.

Jane Ann

[geekinavette]

Oh Jane Ann I so would've messed with my head!

[Brenner]

Thanks guys, I will follow the leads you have given me. I am not out to try to build the fastest CFI, only to give this old girl a little more pep. I figured I'd start out small, better exhaust flow (high flow converters), port the intake, throttle body spacers, and let it breathe a little more. I am going to replace the valve seals so while I am in there I plan to replace the stock 1.5 ratio racker with stamped roller tip 1.6 ratio replacements that will fit under the stock cover. I want to clean it up so when I replace the front timing cover seal I will pull the cover and give her a double rollor chain and gear set. Cheap upgrades, even like a hotter spark as I am on the chase for a Davis Unified Ignition system, and I have the Hypertech street/strip chip, thermostat and coolant fan switch already as well as the Taylor spiro ignition wires. I have just acquired a new pair of Koni red 3 way adjustable shocks for the rear and am looking for a set for the front. The way I see it if I need to replace a part as maintenance I might as well try to improve it while in there. I am currently looking into throttle body rebuild kits and that is another reason I asked the previous questions. Any advice aside from doing away with the crossfire I will consider. I have always wanted an 84 vette and this car fell into my hands on a deal. I literally paid nothing for it and allowed a credit for it on trade for another car I sold.

[geekinavette]

Throttle body spacers wont do anything for it other than cause air cleaner to hood clearance issues. TBI "rebuild kits" are just gaskets and O-rings. The one thing that will help a lot is getting throttle shaft bushings installed if there is any play at all in the shafts (and they almost always do). Get in touch with Dynamic Crossfire Solutions, they do this. Also a good sync of the TBs is very important. You might also consider having the TB's bored to 2". No amount of breathing improvements will help unless it can get through the TB's! I think i might have a set here actually if you're interested.

The "Hyper" chip will just add some spark advance at WOT, make sure to use a higher grade fuel.

No downside to the high flow CAT, the ECM doesn't monitor that. Dont expect much for performance improvement since the stock exhaust manifolds are....in a word, crap.

Also consider upgrading to at least an '85-'89 fuel pump. The 82/84 pump is barely able to handle a stock CFI engine, any extra "pep" at all and the stock fuel pump won't cut it.

At some point the ECM will also not be able to keep up. There are solutions out there at that point, but it's going to be mostly DIY as far as tuning goes. Thirdgen.org is an excellemt resource for DIY tuning. Also look up the Crossfire Injection Vault forums, lots of info there. (just google it)

[Brenner]

In my experience (not with crossfire but rather tbi) I had run spacers and gained a little more bottom end. Guess I am wrong in this application so thank you for correcting me and I did know I could not go much due to clearances. My TBI kits are not for performance but rather becuase when I got the car there was water in the tank ( I cleaned the whole fuel system dry) and with the previous owner trying to start it the water made its way through the whole fuel system. After clearing the accumulator and pressure regulator and injector screens of some light varnish and debris (just to make it run to drive it home) I have decided to clean correctly (ultrasonic for the injectors) and rebuild the throttle bodies ( I was planning on inspecting and replacing the bushings if needed). Also as you mentioned I am planning on replacing the fuel pump as right now I have it running on a TBI pump (old pump was intermitent due to water) and want to be sure to have the correct volume fed to the injection system (pressure don't bother me as I can use the pressure regulator to adjust ). I agree that if the bores of the throttle bodies were enlarged the whole system would benefit and I think that will be step two ( I also know how to sync the throttle bodies and have the correct WC setup and factory service manuals to do this) Now for my tuning chip (hypertech) I needed a coolant temp sensor and wanted to run a cooler setting and t-stat so I went on ebay and bought the chip, stat, and sensor for $75 shipped brand new. I have read that the hypertech changes the lockup in the torque converter and I hope this will be beneficial for me and I do like the idea of keeping the engine running cooler than stock. I do recognize the need for high octane fuel. Exhaust, I will build my own and am going true duals with a mellow sound as I am experienced and have access to the equipment (former shop I worked in). Sorry I am getting off topic, and again thankyou for your input for me it is food for thought. It is always nice to have someone experienced tell you the path they took and their results. Is it fair to say in your opinion I should wait to save the few bucks and jump up and go bigger all in one shot? I do have to watch the pocket book. All in all I just thought I'd run the car a little better than stock to see if I like it before diving in. I haven't had the pleasure of owning or driving one previously. I feel it is a whole different animal than my 1970 Pontiac Trans Am.

[Brenner]

Yoda, thank you for the link, unfortunatley when I click it it takes me to a screen that tells me no matches found. I will see what I can also find.

[geekinavette]

The throttle body shaft bores didn't have bushings installed from GM, just a steel shaft in an aluminum bore. They have to be machined to accept shaft bushings.

I dont know what tool the FSM mentions for syncing, but boring the TBs removes the restriction in the balance ports so keep that in mind. A simple water manometer from a few bucks worth of material used in a differential configuration works beautifully. I think i did a thread about that once upon a time...I'm sure Yoda can find it.

No i wouldn't go "all out" right now, if you end up going beyond the ECM's capability then you'll be spending every waking moment for the next year fighting to get the thing tuned. Trust me this is NOT a simple chore, especially with an 84. It is doable, but if you want to go there it will take some $$ and a helluva lot of time. Keep it to the simple things you have mentioned, ENJOY driving the car for a while and re-evaluate.

[geekinavette]

Yoda, thank you for the link, unfortunatley when I click it it takes me to a screen that tells me no matches found. I will see what I can also find.

Hah i thought it was just me! Doesn't work for me either. (I was curious! )

Yoda fix, he will...persistent he is!

[Brenner]

Thanks Bill, I just learned of your experience and name from Yoda's recommendation. I respectfully take your advice and thank you for the further insight of what is involved in throttle shaft/bore repair/replacement (I truthfully haven't even looked at them yet). I was really shocked when I read the thread of you losing Vettie, and then to learn of the near stock intake you were running at the time. You are so right with what you preach and there are many different combinations that can and may work if one takes the time to explore them. In that same thread I see you were out of work, kind of a similar situaton to mine right now. We both had the Z51 and ironically you car is kinda what I pictured turning mine into over time. Only thing I see different is I have less miles but with it sitting in a garage for the last 5 years, water in tank, I had other hurdles to overcome just to get it on the road. When you mentioned a water manometer I understand and basically a water column (WC) guage is the same thing. I also have a carb syncronizer that is used with mercury. I am a licensed tech and my forte is electrical, drivability, and diagnostics thus why I feel I am able to understand and not need help with the more common concerns others struggle with. I am open minded and please do not ever feel that you are wasting your time with advice or constructive critisism for I do listen and consider all things mentioned. I may not agree or may think differently but am always ready to look at an issue from all angles and consider it. With help from people like you and those I personally deal with, my first vette will be clean enough to drive with a little more spunk for under $2500 (purchase price and taxes included).