I have an 84 Corvette Crossfire with almost 100K miles on it. When I did the tune-up, I noticed that the old spark plugs had oil on the threads, which, from what I've read, could be due to worn gaskets and/or worn rings. So I'm thinking about rebuilding my engine; that's where my question comes in.

I've thought about stroking the motor in my vette, and from what I've read, it seems that the crossfire setup is not suitable for a 383 stroker. Additionally, I've read on this forum that stroking the crossfire will require changes to the ECM. So that brings up a few more questions...

1. Can the crossfire system handle a 383 with ported intake and perhaps ported TB's? How about the injectors, can or should I get bigger ones?

2. Can the 2 bolt main L83 handle the torque that would come from a stroker? Would it need to be upgraded with splayed caps?

3. If I have to upgrade the ECM to handle the stroker, at that point, would it better to just upgrade to a different EFI system, since a new EFI would also require a change to the ECM? I'd rather not, since that can get even more expensive.

To help with answering my questions, here are my parameters:

A. I don't plan on going above 5K RPM ever. This is will be my regular daily driver, I don't plan on taking it to the track. I just wanna feel the power when I take off from a stoplight and when I'm driving on the highway . It's also an ego issue, I want to be able to say that my car has 425-450 lb-fts of torque.

B. I want the car to be emissions compliant. I'm moving to Texas, and they require smog testing on this type of car, so I want to keep the emissions features on it.

C. I want to keep all the electronic functionality in the car (dash, ac, power windows, etc.

D. I am leaning towards torque over horsepower

I welcome all comments, and thank you all in advance for them.
Keep on modding!

 

Stock CFI intakes suck! I'd get the X-ram if I were you. If you do still decide to use the stock intake, it must be ported adequately in order to aid the airflow. Get a nice mild cam like the LT4 hotcam as to compliment the 383. I have a 2 bolt main stroked to a 383 so you should be fine in all aspects. The stock tune should be fine, although the 383 would want a bit more fuel enrichment to avoid a lean condition.

 

Well, the stock crossfire manifold when very ported can kinda handle a 383, but you would be better off with one of the aftermarket crossfire-style choices (Offy, SY-10, XRam, etc). The ported stock manifold would make a really torquey 383 with proper cam choice, but it would be definitely lacking on the topend.

2-Bolt 383's are fine as long as they're built/balanced right and not abused too much. I've got a 383 out of my stock L83 block and it's fine.

ECM really depends on cam choice. I *think* you could get the stock ECM to run a 383 but you'll have to stick to a much milder cam. You'll be better off changing ECM's. The new EBL ECM's for the crossfire are much easier to tune than the old ones, but still a bit tricky if you've never done one before.

If torque is your goal, then the stock ECM and ported stock manifold can be used if properly mated to the rest of the components. Cam choice is the biggest issue. YOu might wanna talk to the guys over at

http://crossfire.home-ip.net

 

I've read that the Powermax 2040 Cam (don't remember the part #) is a good choice for the Crossfire. Would that be a good cam for a 383 Crossfire with the ported manifold and stock ECM?

 

Your parameters of what you want can easily be found in just keeping it the 350. Do you really need it to be a 383?

 

So you mean that I can get 425-450 lb-ft of torque at the flywheel out of the 350? If so, how? That's a very big increase from the stock 290 lb-ft.

 

I never said you can get that at your flywheel.
I'll break it down a bit. Your not looking to race the car right? Your only looking for a fun street car with some ***** is what I get from your parameters. That can be done quite easily.
All I asked is do you need it to be a 383. I'm pretty sure that you will find if you want that much horsepower you will need to tune. Don't expect to get that with your stock ecm. Just with my mods I've listed I'm tuning and thats only the 350.
I was only making a suggestion not a claim on hp/tq
I would suggest going to the crossfire forum to get some good input from those guys.

 

A 383 makes a cam seem more mild, as a rule of thumb. So, a cam that is a bit too rough for the stock ECM in a 350 is ok in a 383. I think you can go bigger than a 2040 in a 383, but in a 350 it's a fine cam.

 

So what size cam would you recommend for a 383, if I was to keep the stock ECM?

It seems that making this work (383 with stock ECM) comes down to the cam. Well, not just that, but it's one of the biggest players in this combo.

 

Don't think the stock ecm will be too efficient with a 383 reguardless of cam. Will it run? Yes, but your wasting you $'s unless you upgrade the ecm.

As far as a ported stock manifold w/ a 383 I think your pushing it. If your dead set on a 383 then look @ the X-Ram, but then again you'll need better heads as well.

If you are able to reach your torque goal, you'll also be looking for a D44 shortly after you grenade your D36 with that much torque.

 

From what I remember the X-fire is not much better then the stock crossfire

 

You realy need to get a hold of a few of the guys that have actualy modified the X-Fire with good results, I would start with elkabong, Dominic Sorresso, and CFI-EFI. A 383 X-fire has been done many time with good results also take a look here for more info
http://www.crossfireforum.org

 

There is a lot of baloney above. If you are going to tear it down anyhow, it costs little extra to put it back together as a 383. For your goals, a ported stock manifold will be more than adequate. It has been said that you need an X-Ram and ported heads to support the top end. With a 5000 rpm limit (your words) you have no desire for a top end. The stock ECM will control your mild mannered, smog legal 383. Don't let these dreamers, anxious to spend other people's money, make a simple task, complicated.

RACE ON!!!

 

I want to thank all of you so far for your comments and input up to now. Based on ya'lls comments, this is the direction in which I'm leaning:

Block: 383
Intake: Ported crossfire (I looked at the X-Ram, and it seems pretty expensive, and I'd lose low-end torque (MAJOR NO NO!), although, what if I put a plate down the middle of that huge port on the Weiand manifold?!)
Throttle Bodies: Stock
Cam: Crane Powermax 2030
Heads: Not sure yet, need input here
ECM: I think I'll just upgrade it, what the heck.

Aside from that, js292 gave me some good pointers on other mods:
Tri-Y Headers
2500 Stall Converter
3.54 gears (how about 3:73's, what's the difference?)
Dana 44
1:6 RR's
Free-flowing cat and exhaust: This brings up another question: Since I'll live in Houston, I need to retain the smog functionality, so, could I install a true-dual exhuast system (maybe twin cats) and still keep my emissions legality?

This is where I'm at so far. Anybody, please let me know what you consider weak points, if you know the answers to some of the questions above, etc.

Thanks again!

 

3:73's in a D36 aren't reccommend by most builders, they say the case is too weak. The most cost effective way if you come across one would be to find a 89-90 6spd car with a D44, they usally have 3:45's in them. There getting harder to find but if you find one from someone who doesn't know what they have you can usally pick it up pretty cheap. (not around here though)

 

Yeah, in the previous post I mentioned Dana 44, because I've heard the same thing, so might as well upgrade to the beefier differential.

Now, about the gears, I've heard people who have 3.54's or 3.73's, and they each like them a lot. So what's the difference between them?

Also, I've just heard back from Stan at Stan's Headers, and he said they don't make Tri-Y's for 84 Corvettes, but I just found Melrose Motorsports, and they make an entire exhaust system (headers, x-pipe, dual cats, and rear pipes) for 84-85 corvettes that includes smog functionality (A.I.R., EGR, etc), so I think that's the best choice for exhuast mods and the closest I see that is emissions legal dual exhaust.

Back to the 383, I'm still not sure if it would be worth boring out the throttle bodies, if I'm keeping the ported manifold. What do you guys think?

 

Sorry, I knew Stan's didn't make them. They are from someone else, here's the link;

http://cgi.ebay.com/ebaymotors/LT1-L...spagenameZWDVW

The Melrose set up is nice.

 

Although you have started piecing together a combo, I thought I'd still answer your questions since I have some experience w/this topic...

It can. I ran a ported CFI intake on a SBC 400 for a few years, and it worked good for me. Mid-low 13's and over 24 mpg hwy.


Already answered above.


You don't NEED to upgrade the ECM, though doing so will allow you to custom tune, and FULLY optimize your combo. My car was a CFI Trans Am so it originally came w/the 165hp 305 CFI engine. I was running my 400 on the stock original ECM, w/the stock chip. It idled like stock, started in 1 compression stroke, and performed as described above. Also, My GF at the time didn't like the car b/c stepping on the gas "gave her whiplash"...in her words. It had sh1tloads of torque below 5k RPM.

 

Throw the CFI in the ditch if you want to maximize power. Why build a strong motor and hobble it with a sucky intake?

 

...coming from two guys who have never touched one.