View Poll Results: do it
Do it, it's fun
31
72.09%
Do it but I don't think it'll be accurate
1
2.33%
Don't do it, it is a waste of your time
3
6.98%
Save your time and drink
4
9.30%
Just drive it
4
9.30%
Voters: 43. You may not vote on this poll
Trying to plan a crossfire experiment
Oil Producer
Joined: Apr 2014
Posts: 9,368
Likes: 2,735
but wait....i thought you just need to port the cfi, use a 85 fuel pump with adjustable fuel pressure regulator in place of the factory one, set to 14psi, and bump timing to like 10deg or something like that and we are at tpi or better levels. ? i mean anyone who gets a used crossfire is more than likely pulling apart to clean it up, and you can probably find a local person or yourself to port the intake following a few well documented online pages...
im not being facetious im actually asking...i have an 84 for my daughter here and that was my plan....is there an easier bolt on plan that “just works”?
I dont want hassle i just want the factory stuff to work.
im not being facetious im actually asking...i have an 84 for my daughter here and that was my plan....is there an easier bolt on plan that “just works”?
I dont want hassle i just want the factory stuff to work.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Something like the SY-1 or an Offy is for chasing bigger power gains....like a 383 CFI w/head, roller cam, etc. You can't port a stock CFI intake enough for a motor like that. But for a stock motor, port the runners, bump FP, advance timing and do exhaust.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
So, I've been doing some serious soul searching... The difference between the theoretical and actual power output is bothering me... So I am curious. What can we all speculate the issue is or more so, what would you all like to see tested/tried on the dyno. I kind of want to pull the mufflers and see if I pick up anything. 3 inch necked down to 2.25 inches out the back may or may not pick up a few horsepower. (You know, because I obviously need the backpressure to make supah torqs. 
) I am thinking that would possibly show a few numbers gain though.
Outside of that, in the current configuration, I don't see much to be improved other than with the tune itself and even that may not be much.
) I am thinking that would possibly show a few numbers gain though.Outside of that, in the current configuration, I don't see much to be improved other than with the tune itself and even that may not be much.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Swirl plates vs. not,
Radiused lid bores or not
Tower spacers vs. none
Parallel plumbing vs. stock/series plumbing
^All things that folks make claims about, but I've never seen diddly to support one way or the other. I don't think the muff's will do squat, but I love ANY dyno comparo's so I'm all
for that, too! 
Radiused lid bores or not
Tower spacers vs. none
Parallel plumbing vs. stock/series plumbing
^All things that folks make claims about, but I've never seen diddly to support one way or the other. I don't think the muff's will do squat, but I love ANY dyno comparo's so I'm all
for that, too!
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
Swirl plates vs. not,
Radiused lid bores or not
Tower spacers vs. none
Parallel plumbing vs. stock/series plumbing
^All things that folks make claims about, but I've never seen diddly to support one way or the other. I don't think the muff's will do squat, but I love ANY dyno comparo's so I'm all for that, too!
Radiused lid bores or not
Tower spacers vs. none
Parallel plumbing vs. stock/series plumbing
^All things that folks make claims about, but I've never seen diddly to support one way or the other. I don't think the muff's will do squat, but I love ANY dyno comparo's so I'm all
for that, too! Swirl plates I planned on testing with the Ported intake. It was going to be as follows:
- Ported with stock lid and TBs
- Ported with deleted swirl plates
- Ported w/o swirl plates and 2 inch TBs
The radiused lid I'll have to look into more.
Burning Brakes
Joined: Sep 2017
Posts: 933
Likes: 165
I can tell you I'm parallel plumbed currently... I tried leaving it in series with just block off plates and had issues. Which after I had the break up issue with the hard lines I think you recall, came to realize that it was probably due to no dampener/accumulator. In anything close to stock or running near stock fuel pressures I can't see any reason to parallel plumb. In my situation I can but that's because the stock diaphragms I doubt would hold up well to 28 psi of pressure long term. If I could find the marine diaphragms which are a thicker rubber I would gladly try it but that's one I don't think I'm brave enough to test.
Swirl plates I planned on testing with the Ported intake. It was going to be as follows:
The radiused lid I'll have to look into more.
Swirl plates I planned on testing with the Ported intake. It was going to be as follows:
- Ported with stock lid and TBs
- Ported with deleted swirl plates
- Ported w/o swirl plates and 2 inch TBs
The radiused lid I'll have to look into more.
there's something about the depth of side walls of the swirl plates that increases the flow. Stock pitch of swirl plates blades worked the best for me. Tried more pitch and less pitch, stock pitch worked the best for me. wasn't much though.
also stock orientation of swirl plates works good. I turned them 360 degrees to see if there was any changes and flow does change a little.
my tests didn't show any gain from radiused lid
Last edited by mike1111; Feb 12, 2023 at 06:35 PM.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
Saw something interesting today watching Engine masters. Not that I think it is particularly relevant to the data at hand but, they were talking about and testing injector placement and had a new spacer under the throttle body called a shear plate for lack of a better term it quite literally looks like our swirl plate (sticks a round cylinder into the plenum) minus the diffuser portion. The alleged purpose is to diffuse the reflective wave. Interesting but for our application it doesn't seem like it would be able to cause enough havoc at the throttle body to be a problem.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
Plus the sudden expansion as it leaves the runner. This was on a tunnel ram type setup iirc. So very much runner line of sight to the baseplate. Pretty much every runner in a CFI would have to be shortened a lot to have that benefit or the pulse would have to make a 180 off the side wall.
Burning Brakes
Joined: Sep 2017
Posts: 933
Likes: 165
Saw something interesting today watching Engine masters. Not that I think it is particularly relevant to the data at hand but, they were talking about and testing injector placement and had a new spacer under the throttle body called a shear plate for lack of a better term it quite literally looks like our swirl plate (sticks a round cylinder into the plenum) minus the diffuser portion. The alleged purpose is to diffuse the reflective wave. Interesting but for our application it doesn't seem like it would be able to cause enough havoc at the throttle body to be a problem.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
precisely. I've actually seen slow motion videos of carbs under WOT conditions and you can actually see back splash through the venturi and out the top of the carb. Pretty cool stuff. I could see back splash being a problem on TBI but not on anything close to what came in the car stock... the reflection just doesn't have enough power behind it and again, large plenum. It is kind of interesting the later TBI intakes had none of this that is present on the CFI despite operating in a similar manner. I do think they had some sort of down leg cast in though. I've never held a TBI intake in hand.
Burning Brakes
Joined: Sep 2017
Posts: 933
Likes: 165
precisely. I've actually seen slow motion videos of carbs under WOT conditions and you can actually see back splash through the venturi and out the top of the carb. Pretty cool stuff. I could see back splash being a problem on TBI but not on anything close to what came in the car stock... the reflection just doesn't have enough power behind it and again, large plenum. It is kind of interesting the later TBI intakes had none of this that is present on the CFI despite operating in a similar manner. I do think they had some sort of down leg cast in though. I've never held a TBI intake in hand.
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,940
Likes: 1,490
From: New Jersey
(5) Long Ram 413 DYNO Tested! - Historic Chrysler Engine - YouTube
30 minute mark. this engine shows it. long runners
30 minute mark. this engine shows it. long runners