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getting 300hp can be done with a good cam and heads. but if you tune it with a different computer you can get 400+.to build from scratch with a goal in mind buccaneer has done it .you already have his intake, matching the correct heads cam and pistons should give you the hp that you want .you can pm him at the corvette forum or you can leave a message at his old site http://crossfireinjection.net/
Cam = use one suitable for the RPM range you want, with/without fuel pump lobe as needed, and with the correct style to suit the timing set (i.e., step-nose roller) Screwing with the cam leads directly to screwing with the PROM or other "computer tuning".
Heads = use two suitable for compression ratio, intake bolt pattern, runner size, valve size, and exhaust flange. You'll have the choice of iron or aluminum.
I'd be looking fairly closely at Summit TBI heads in aluminum.
Cam - look for one that specifies it's for EFI. These generally have wider lobe separation to keep vacuum up. Will make tuning much easier. The very small COMP 252AH in my engine was good for 260 RWHP through a TH-350, which should be close to 300 flywheel HP. I'm thinking about a camp swap, maybe going to the 268H EFI grind.
Heads - there are tons of decent aluminum heads out there that would meet your power goal. I would look for a good deal. Summit Racing has 10% off this weekend. For the current cost of the Edelbrock Performer heads I have ($1700), you can get a set of AFRs. The Edelbrock E Street heads are supposed to be decent and you can get a set of those for around $1100.
For the short block, I would stick with a 350 to stay in budget. If you stick with aluminum heads, go with a 9.5 to 10:1 compression ratio and run premium.
I pretty much described my build above. My car isn't the fastest, but it's much more fun to drive that it as stock.
OK, so you want "300-400 hp ball park and $5,000". You can do that with a 383 or bigger cube motor easily or spend a bit more on a 355/357 motor. Which way are you going? Is this going to be a track car, street car or DD? You need to define what you are going to use the car for mostly and then go from there. Do you have any idea on how to tune a motor or do you have someone that will do all that for you? If you say no to each, then get ready for a HUGE learning curve and is not for the faint of heart the more aggressive you get with the build. Also, keep in mind that you can destroy a brand new motor easy if you screw it up badly and then you get to spend all that money again. There IS a ton of things to consider IMO before you decide on what parts you need to start gathering for the build. There's also other things to consider besides a motor like trans, rear gear, TC etc... it ALL plays into the build. My CR on my new motor is 10.7 and runs just fine on the street on 91 octane pump gas.I bump it up tad to 94/95 when at the track when the laptop comes out and it runs mid 12s now. I dial it back a little for the street on the tune. Still a 12 second car though.
There is NO magic wand for building a good motor, but there IS a lot of sound choices and common sense that goes into those choices. Just to let you know, I DO NOT sell my tune even if your motor was exactly like mine in every way. I have a lot of money invested in my tune over the years on a dyno to get it to where it is today and will not sell it. I say this because I get a lot of mail/PMs asking if I would give out my tune. These are just my opinions and I'm sure others will have a different opinion, which is fine of course. Good luck with your build whichever way you decide to go.
#1 - do not use the factory crossfire intake. The ports are only 2/3 the size of normal intake ports.
Thats what die grinders are for. Porting the base makes a HUGE difference on both 305 and 350 cars. My current LU5 (305) T5 T/A is running 14.30s with a ported base, stock cam, stock 416 heads, 3.73s, shortys and 3” exhaust. I average 18mpg city and 25mpg highway with an 8746 ECM. Daily driver, and reliable as can be.
Thats what die grinders are for. Porting the base makes a HUGE difference on both 305 and 350 cars.
As someone who's done more than enough die-grinding (generally on iron/steel) I'd say that life is too short to carve that much metal out of an intake manifold. Certainly true unless you've got a "REAL" die-grinder, 1/2 horsepower minimum, 1-horse preferred. The cheap-and-common CP and IR and "off-brand" junk die grinders are going to waste a lot of air pressure, time, and enthusiasm.
I think most folks just bolt a different cross-ram base between the heads, and build a plate on top for the TBI units. I've seen flat-plate tops fabricated for the old Offy "GM-clone" cross-ram, as well as for the Smokey Ram. I guess the Renegade is out-of-production.
The only reason to keep the stock manifold is to retain the EGR.
Thats what die grinders are for. Porting the base makes a HUGE difference on both 305 and 350 cars. My current LU5 (305) T5 T/A is running 14.30s with a ported base, stock cam, stock 416 heads, 3.73s, shortys and 3” exhaust. I average 18mpg city and 25mpg highway with an 8746 ECM. Daily driver, and reliable as can be.
I feel like I've seen that car before... maybe... maybe in a moving picture. Or I'm mistaken... which happens a lot.
I agree you can grind a lot out... But theres a lot of other weirdness going on with the flow distribution. On a stockish vehicle it's fine and probably good enough just doing a port match and trimming back the runner openings. The one I'm playing with has such an unreasonable about of welding done to it to correct all the holes made in the thin areas... if I were to do it over I would use the early casting w/o crossovers and make a lid spacer because that actually helped alot. Nothing crazy, but quarter inch made a big difference.
As someone who's done more than enough die-grinding (generally on iron/steel) I'd say that life is too short to carve that much metal out of an intake manifold. Certainly true unless you've got a "REAL" die-grinder, 1/2 horsepower minimum, 1-horse preferred. The cheap-and-common CP and IR and "off-brand" junk die grinders are going to waste a lot of air pressure, time, and enthusiasm.
I think most folks just bolt a different cross-ram base between the heads, and build a plate on top for the TBI units. I've seen flat-plate tops fabricated for the old Offy "GM-clone" cross-ram, as well as for the Smokey Ram. I guess the Renegade is out-of-production.
The only reason to keep the stock manifold is to retain the EGR.
Well I have had a Renegade on this car. Tom from DCS lives 40 minutes from me. He actually gave me the manifold for free. As far as how much “time” needs to be put into an LU5/L83 manifold, it doesn’t take much to see impressive results. I knocked 7 tenths off my ET just be shortening the runners, and opening them up, again, on a 305 with the stock cam and heads. No flow bench involved, just taking car of what GM should have done in the first place. I’m well aware of why the runners were necked down to 2/3 of the size of a standard SBC manifold (increase port velocity to cure fuel puddling issues), but porting the CFI base is a well known and proven modification, that only costs time, and it’ll be as good as the time you put into it. I’m not afraid of WORK.
Last edited by 1983LU5TA; Aug 31, 2022 at 04:54 AM.
LU5 is low hanging fruit; it's super easy to make big gains from it. I went 14.5@95 in my '83 with Edelbrock "headers", and "free mods".
As for "not" porting the stock intake? IDK...it's pretty easy port'n...and it's free and effective.
But but but... not everyone has a two stage compressor or the ability to pick up a cheap electric grinder from harbor freight tom. (sorry I had to lol.) You need to stop making sense now.
I'm going to be completely honest... I want to find another stock 4 speed 84 that runs and then go through and document each step and see what does what. That intake is just looking for a home... or maybe I'll just sell it... or put it in the trophy room with the other oddball car parts I have laying around... I still want to see how much further I can take it and what it does... Maybe over the winter. I know for certain it isn't going on the 388 when that is eventually done. Well maybe for monstah tork ala L98 style.
But but but... not everyone has a two stage compressor or the ability to pick up a cheap electric grinder from harbor freight tom. (sorry I had to lol.) You need to stop making sense now.
I'm going to be completely honest... I want to find another stock 4 speed 84 that runs and then go through and document each step and see what does what. That intake is just looking for a home... or maybe I'll just sell it... or put it in the trophy room with the other oddball car parts I have laying around... I still want to see how much further I can take it and what it does... Maybe over the winter. I know for certain it isn't going on the 388 when that is eventually done. Well maybe for monstah tork ala L98 style.
If you do decide to get rid of the manifold, let me know. I’ll buy it off ya.
If you do decide to get rid of the manifold, let me know. I’ll buy it off ya.
Will do. I'm going to hopefully get it back on the flow bench this winter after I tweak it and see how it shapes up to stock. Depending, I may also make a lid spacer. I'll never get back the time I have in it... figure 20 hours of my own labor. I'd just want to cover the cost of the materials. I'll shoot you PM if I do decide to sell it and we'll talk a price. Figure shipping would be about 25$. Aside from time there isn't much into it.
Heck, if you want to just mess around with it and test it I would be more then glad to just send it your way.
But but but... not everyone has a two stage compressor or the ability to pick up a cheap electric grinder from harbor freight tom. (sorry I had to lol.) You need to stop making sense now.
I'm going to be completely honest... I want to find another stock 4 speed 84 that runs and then go through and document each step and see what does what.
I've wanted to do that for YEARS; find a decent RUNNING or salvageable running gear, manual trans '84 and document the improvements. I keep my eyes open...but there aren't many sticks for cheap....and my wife would kill me if I added to the 'Vette + Kart fleet. :ack:
I've wanted to do that for YEARS; find a decent RUNNING or salvageable running gear, manual trans '84 and document the improvements. I keep my eyes open...but there aren't many sticks for cheap....and my wife would kill me if I added to the 'Vette + Kart fleet. :ack:
There was one around here. Basically mine, black on black. But while the interior was okay it was too far gone when i took a look at it. Engine was locked up so id have been starting from a skew to begin with. Not worth the time.
The whole point of the Vortec IS the heads. It already comes with good heads.
Yes. The Vortec heads are wonderful.
This thread is about crossfire intake manifolds and the engines they attach to, and you're unlikely to get a crossfire manifold to bolt to OEM Vortec heads, or cover the extra-tall Vortec ports.
Sure, you can weld and kludge the manifold and the heads to make it all fit...but most folks wouldn't.
Point being, if you find an adequate CAR that happens to be missing an ENGINE, there's heaps of suitable short-blocks in the Treasure Yard. I certainly wouldn't let the absence of an engine cause me to miss out on buying the car I wanted. The downside to not having an engine in the car, is the missing accessories--the mounts for the alternator, PS, A/C, etc; the potential damage to wiring harnesses, etc. Not the loss of the actual engine itself.
This thread is about crossfire intake manifolds and the engines they attach to, and you're unlikely to get a crossfire manifold to bolt to OEM Vortec heads, or cover the extra-tall Vortec ports.
Sure, you can weld and kludge the manifold and the heads to make it all fit...but most folks wouldn't.
Point being, if you find an adequate CAR that happens to be missing an ENGINE, there's heaps of suitable short-blocks in the Treasure Yard. I certainly wouldn't let the absence of an engine cause me to miss out on buying the car I wanted. The downside to not having an engine in the car, is the missing accessories--the mounts for the alternator, PS, A/C, etc; the potential damage to wiring harnesses, etc. Not the loss of the actual engine itself.
A vortec engine is an aluminum head swap away from running under a crossfire manifold.
Heaps and piles of Vortec and TBI 5.7L engines in the Treasure Yard.
Select a prime core, dingle-berry-brush the cylinders, clean the pistons, fresh bearings 'n' rings 'n' gaskets/seals.
Spend the money on decent cylinder heads and computer tuning.
The problem is most places, at least here, you're not getting a nice core. Yeah I could spend 800$ and get something decent but that still defeats the purpose kind of. I get it though.
that being said I'm pretty sure Tom has gotten a CFI manifold onto a vortec head. Maybe have even been with CFI-EFI if I remember correctly? I know he's told me several times and a stock intake will cover a 1205 and possibly a 1206 felpro (I'd have to check again) if you're very careful.
